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5 款适合程序员的开源字体
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======
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> 编程字体有些在普通字体中没有的特点，这五种字体你可以看看。
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什么是最好的编程字体呢？首先，你需要考虑到字体被设计出来的初衷可能并不相同。当选择一款用于休闲阅读的字体时，读者希望该字体的字母能够顺滑地衔接，提供一种轻松愉悦的体验。一款标准字体的每个字符，类似于拼图的一块，它需要被仔细的设计，从而与整个字体的其他部分融合在一起。
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然而，在编写代码时，通常来说对字体的要求更具功能性。这也是为什么大多数程序员在选择时更偏爱使用固定宽度的等宽字体。选择一款带有容易分辨的数字和标点的字体在美学上令人愉悦；但它是否拥有满足你需求的版权许可也是非常重要的。
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某些功能使得字体更适合编程。首先要清楚是什么使得等宽字体看上去井然有序。这里，让我们对比一下字母 `w` 和字母 `i`。当选择一款字体时，重要的是要考虑字母本身及周围的空白。在纸质的书籍和报纸中，有效地利用空间是极为重要的，为瘦小的 `i` 分配较小的空间，为宽大的字母 `w` 分配较大的空间是有意义的。
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然而在终端中，你没有这些限制。每个字符享有相等的空间将非常有用。这么做的首要好处是你可以随意扫过一段代码来“估测”代码的长度。第二个好处是能够轻松地对齐字符和标点，高亮在视觉上更加明显。另外打印纸张上的等宽字体比均衡字体更加容易通过 OCR 识别。
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在本篇文章中，我们将探索 5 款卓越的开源字体，使用它们来编程和写代码都非常理想。
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### 1、Firacode：最佳整套编程字体
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![FiraCode 示例][1]
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*FiraCode, Andrew Lekashman*
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在我们列表上的首款字体是 [FiraCode][3]，一款真正符合甚至超越了其职责的编程字体。FiraCode 是 Fira 的扩展，而后者是由 Mozilla 委托设计的开源字体族。使得 FiraCode 与众不同的原因是它修改了在代码中常使用的一些符号的组合或连字，使得它看上去更具可读性。这款字体有几种不同的风格，特别是还包含 Retina 选项。你可以在它的 [GitHub][3] 主页中找到它被使用到多种编程语言中的例子。
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![FiraCode compared to Fira Mono][2]
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*FiraCode 与 Fira Mono 的对比，[Nikita Prokopov][3]，源自 GitHub*
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### 2、Inconsolata：优雅且由卓越设计者创造
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![Inconsolata 示例][4]
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*Inconsolata, Andrew Lekashman*
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[Inconsolata][5] 是最为漂亮的等宽字体之一。从 2006 年开始它便一直是一款开源和可免费获取的字体。它的创造者 Raph Levien 在设计 Inconsolata 时秉承的一个基本原则是：等宽字体并不应该那么糟糕。使得 Inconsolata 如此优秀的两个原因是：对于 `0` 和 `o` 这两个字符它们有很大的不同，另外它还特别地设计了标点符号。
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### 3、DejaVu Sans Mono：许多 Linux 发行版的标准配置，庞大的字形覆盖率
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![DejaVu Sans Mono example][6]
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*DejaVu Sans Mono, Andrew Lekashman*
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受在 GNOME 中使用的带有版权和闭源的 Vera 字体的启发，[DejaVu Sans Mono][7] 是一个非常受欢迎的编程字体，几乎在每个现代的 Linux 发行版中都带有它。在 Book Variant 风格下 DejaVu 拥有惊人的 3310 个字形，相比于一般的字体，它们含有 100 个左右的字形。在工作中你将不会出现缺少某些字符的情况，它覆盖了 Unicode 的绝大部分，并且一直在活跃地增长着。
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### 4、Source Code Pro：优雅、可读性强，由 Adobe 中一个小巧但天才的团队打造
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![Source Code Pro example][8]
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*Source Code Pro, Andrew Lekashman*
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由 Paul Hunt 和 Teo Tuominen 设计，[Source Code Pro][9] 是[由 Adobe 创造的][10]，成为了它的首款开源字体。Source Code Pro 值得注意的地方在于它极具可读性，且对于容易混淆的字符和标点，它有着非常好的区分度。Source Code Pro 也是一个字体族，有 7 中不同的风格：Extralight、Light、Regular、Medium、Semibold、Bold 和 Black，每种风格都还有斜体变体。
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![Differentiating potentially confusable characters][11]
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*潜在易混淆的字符之间的区别，[Paul D. Hunt][10] 源自 Adobe Typekit 博客。*
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![Metacharacters with special meaning in computer languages][12]
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*在计算机领域中有特别含义的特殊元字符， [Paul D. Hunt][10] 源自 Adobe Typekit 博客。*
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### 5、Noto Mono：巨量的语言覆盖率，由 Google 中的一个大团队打造
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![Noto Mono example][13]
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*Noto Mono, Andrew Lekashman*
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在我们列表上的最后一款字体是 [Noto Mono][14]，这是 Google 打造的庞大 Note 字体族中的等宽版本。尽管它并不是专为编程所设计，但它在 209 种语言（包括 emoji 颜文字！）中都可以使用，并且一直在维护和更新。该项目非常庞大，是 Google 宣称 “组织全世界信息” 的使命的延续。假如你想更多地了解它，可以查看这个绝妙的[关于这些字体的视频][15]。
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### 选择合适的字体
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无论你选择那个字体，你都有可能在每天中花费数小时面对它，所以请确保它在审美和哲学层面上与你产生共鸣。选择正确的开源字体是确保你拥有最佳生产环境的一个重要部分。这些字体都是很棒的选择，每个都具有让它脱颖而出的功能强大的特性。
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--------------------------------------------------------------------------------
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via: https://opensource.com/article/17/11/how-select-open-source-programming-font
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作者：[Andrew Lekashman][a]
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译者：[FSSlc](https://github.com/FSSlc)
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校对：[wxy](https://github.com/wxy)
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本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
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[a]:https://opensource.com
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[1]:https://opensource.com/sites/default/files/u128651/firacode.png (FiraCode example)
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[2]:https://opensource.com/sites/default/files/u128651/firacode2.png (FiraCode compared to Fira Mono)
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[3]:https://github.com/tonsky/FiraCode
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[4]:https://opensource.com/sites/default/files/u128651/inconsolata.png (Inconsolata example)
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[5]:http://www.levien.com/type/myfonts/inconsolata.html
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[6]:https://opensource.com/sites/default/files/u128651/dejavu_sans_mono.png (DejaVu Sans Mono example)
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[7]:https://dejavu-fonts.github.io/
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[8]:https://opensource.com/sites/default/files/u128651/source_code_pro.png (Source Code Pro example)
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[9]:https://github.com/adobe-fonts/source-code-pro
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[10]:https://blog.typekit.com/2012/09/24/source-code-pro/
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[11]:https://opensource.com/sites/default/files/u128651/source_code_pro2.png (Differentiating potentially confusable characters)
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[12]:https://opensource.com/sites/default/files/u128651/source_code_pro3.png (Metacharacters with special meaning in computer languages)
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[13]:https://opensource.com/sites/default/files/u128651/noto.png (Noto Mono example)
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[14]:https://www.google.com/get/noto/#mono-mono
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[15]:https://www.youtube.com/watch?v=AAzvk9HSi84
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12 个最佳 GNOME（GTK）主题
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> 让我们来看一些漂亮的 GTK 主题，你不仅可以用在 Ubuntu 上，也可以用在其它使用 GNOME 的 Linux 发行版上。
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对于我们这些使用 Ubuntu 的人来说，默认的桌面环境从 Unity 变成了 Gnome 使得主题和定制变得前所未有的简单。Gnome 有个相当大的定制用户社区，其中不乏可供用户选择的漂亮的 GTK 主题。最近几个月，我不断找到了一些喜欢的主题。我相信这些是你所能找到的最好的主题之一了。
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### Ubuntu 和其它 Linux 发行版的最佳主题
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这不是一个详细清单，可能不包括一些你已经使用和喜欢的主题，但希望你能至少找到一个能让你喜爱的没见过的主题。所有这里提及的主题都可以工作在 Gnome 3 上，不管是 Ubuntu 还是其它 Linux 发行版。有一些主题的屏幕截屏我没有，所以我从官方网站上找到了它们的图片。
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在这里列出的主题没有特别的次序。
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但是，在你看这些最好的 GNOME 主题前，你应该学习一下 [如何在 Ubuntu GNOME 中安装主题][1]。
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#### 1、Arc-Ambiance
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![][2]
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Arc 和 Arc 变体主题已经出现了相当长的时间，普遍认为它们是最好的主题之一。在这个示例中，我选择了 Arc-Ambiance ，因为它是 Ubuntu 中的默认 Ambiance 主题。
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我是 Arc 主题和默认 Ambiance 主题的粉丝，所以不用说，当我遇到一个融合了两者优点的主题，我不禁长吸了一口气。如果你是 Arc 主题的粉丝，但不是这个特定主题的粉丝，Gnome 的外观上当然还有适合你口味的大量的选择。
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- [下载 Arc-Ambiance 主题][3]
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#### 2、Adapta Colorpack
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![][4]
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Adapta 主题是我所见过的最喜欢的扁平主题之一。像 Arc 一样，Adapata 被很多 Linux 用户广泛采用。我选择这个配色包，是因为一次下载你就有数个可选择的配色方案。事实上，有 19 个配色方案可以选择，是的，你没看错，19 个呢！
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所以，如果你是如今常见的扁平风格/<ruby>材料设计风格<rt>Material Design Language</rt></ruby>的粉丝，那么，在这个主题包中很可能至少有一个能满足你喜好的变体。
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- [下载 Adapta Colorpack 主题][5]
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#### 3、Numix Collection
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![][6]
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啊，Numix! 让我想起了我们一起度过的那些年！对于那些在过去几年装点过桌面环境的人来说，你肯定在某个时间点上遇到过 Numix 主题或图标包。Numix 可能是我爱上的第一个 Linux 现代主题，现在我仍然爱它。虽然经过这些年，但它仍然魅力不失。
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灰色色调贯穿主题，尤其是默认的粉红色高亮，带来了真正干净而完整的体验。你可能很难找到一个像 Numix 一样精美的主题包。而且在这个主题包中，你还有很多可供选择的余地，简直不要太棒了！
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- [下载 Numix Collection 主题][7]
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#### 4、Hooli
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![][8]
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Hooli 是一个已经出现了一段时间的主题，但是我最近才偶然发现它。我是很多扁平主题的粉丝，但是通常不太喜欢材料设计风格的主题。Hooli 像 Adapta 一样吸取了那些设计风格，但是我认为它和其它的那些有所不同。绿色高亮是我对这个主题最喜欢的部分之一，并且，它在不冲击整个主题方面做的很好。
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- [下载 Hooli 主题][9]
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#### 5、Arrongin/Telinkrin
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![][10]
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福利：二合一主题！它们是在主题领域中的相对新的竞争者。它们都吸取了 Ubuntu 接近完成的 “[communitheme][11]” 的思路，并带它到了你的桌面。这两个主题我能找到的唯一真正的区别就是颜色。Arrongin 以 Ubuntu 家族的橙色颜色为中心，而 Telinkrin 则更偏向于 KDE Breeze 系的蓝色，我个人更喜欢蓝色，但是两者都是极好的选择！
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- [下载 Arrongin/Telinkrin 主题][12]
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#### 6、Gnome-osx
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![][13]
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我不得不承认，通常，当我看到一个主题有 “osx” 或者在标题中有类似的内容时我就不会不期望太多。大多数受 Apple 启发的主题看起来都比较雷同，我真不能找到使用它们的原因。但我想这两个主题能够打破这种思维定式：这就是 Arc-osc 主题和 Gnome-osx 主题。
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我喜欢 Gnome-osx 主题的原因是它在 Gnome 桌面上看起来确实很像 OSX。它在融入桌面环境而不至于变的太扁平方面做得很好。所以，对于那些喜欢稍微扁平的主题的人来说，如果你喜欢红黄绿按钮样式（用于关闭、最小化和最大化），这个主题非常适合你。
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- [下载 Gnome-osx 主题][14]
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#### 7、Ultimate Maia
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![][15]
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曾经有一段时间我使用 Manjaro Gnome。尽管那以后我又回到了 Ubuntu，但是，我希望我能打包带走的一个东西是 Manjaro 主题。如果你对 Manjaro 主题和我一样感受相同，那么你是幸运的，因为你可以带它到你想运行 Gnome 的任何 Linux 发行版！
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丰富的绿色颜色，Breeze 式的关闭、最小化、最大化按钮，以及全面雕琢过的主题使它成为一个不可抗拒的选择。如果你不喜欢绿色，它甚至为你提供一些其它颜色的变体。但是说实话……谁会不喜欢 Manjaro 的绿色呢？
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- [下载 Ultimate Maia 主题][16]
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#### 8、Vimix
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![][17]
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这是一个让我激动的主题。它是现代风格的，吸取了 macOS 的红黄绿按钮的风格，但并不是直接复制了它们，并且减少了多变的主题颜色，使之成为了大多数主题的独特替代品。它带来三个深色的变体和几个彩色配色，我们中大多数人都可以从中找到我们喜欢的。
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- [下载 Vimix 主题][18]
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#### 9、Ant
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![][19]
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像 Vimix 一样，Ant 从 macOS 的按钮颜色中吸取了灵感，但不是直接复制了样式。在 Vimix 减少了颜色花哨的地方，Ant 却增加了丰富的颜色，在我的 System 76 Galago Pro 屏幕看起来绚丽极了。三个主题变体的变化差异大相径庭，虽然它可能不见得符合每个人的口味，它无疑是最适合我的。
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- [下载 Ant 主题][20]
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#### 10、Flat Remix
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![][21]
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如果你还没有注意到这点，对于一些关注关闭、最小化、最大化按钮的人来说我就是一个傻瓜。Flat Remix 使用的颜色主题是我从未在其它地方看到过的，它采用红色、蓝色和橙色方式。把这些添加到一个几乎看起来像是一个混合了 Arc 和 Adapta 的主题的上面，就有了 Flat Remix。
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我本人喜欢它的深色主题，但是换成亮色的也是非常好的。因此，如果你喜欢稍稍透明、风格一致的深色主题，以及偶尔的一点点颜色，那 Flat Remix 就适合你。
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- [下载 Flat Remix 主题][22]
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#### 11、Paper
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![][23]
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[Paper][24] 已经出现一段时间。我记得第一次使用它是在 2014 年。可以说，Paper 的图标包比其 GTK 主题更出名，但是这并不意味着它自身的主题不是一个极好的选择。即使我从一开始就倾心于 Paper 图标，我不能说当我第一次尝试它的时候我就是一个 Paper 主题忠实粉丝。
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我觉得鲜亮的色彩和有趣的方式被放到一个主题里是一种“不成熟”的体验。现在，几年后，Paper 在我心目中已经长大，至少可以这样说，这个主题采取的轻快方式是我非常欣赏的一个。
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- [下载 Paper 主题][25]
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||||
#### 12、Pop
|
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||||
![][26]
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||||
Pop 在这个列表上是一个较新的主题，是由 [System 76][27] 的人们创造的，Pop GTK 主题是前面列出的 Adapta 主题的一个分支，并带有一个匹配的图标包，图标包是先前提到的 Paper 图标包的一个分支。
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||||
该主题是在 System 76 发布了 [他们自己的发行版][28] Pop!_OS 之后不久发布的。你可以阅读我的 [Pop!_OS 点评][29] 来了解更多信息。不用说，我认为 Pop 是一个极好的主题，带有华丽的装饰，并为 Gnome 桌面带来了一股清新之风。
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|
||||
- [下载 Pop 主题][30]
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||||
#### 结束语
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||||
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||||
很明显，我们有比文中所描述的主题更多的选择，但是这些大多是我在最近几月所使用的最完整、最精良的主题。如果你认为我们错过一些你确实喜欢的主题，或你确实不喜欢我在上面描述的主题，那么在下面的评论区让我们知道，并分享你喜欢的主题更好的原因！
|
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||||
--------------------------------------------------------------------------------
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|
||||
via: https://itsfoss.com/best-gtk-themes/
|
||||
|
||||
作者：[Phillip Prado][a]
|
||||
译者：[robsean](https://github.com/robsean)
|
||||
校对：[wxy](https://github.com/wxy)
|
||||
选题：[lujun9972](https://github.com/lujun9972)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:https://itsfoss.com/author/phillip/
|
||||
[1]:https://itsfoss.com/install-themes-ubuntu/
|
||||
[2]:https://i2.wp.com/itsfoss.com/wp-content/uploads/2018/03/arcambaince.png
|
||||
[3]:https://www.gnome-look.org/p/1193861/
|
||||
[4]:https://i0.wp.com/itsfoss.com/wp-content/uploads/2018/03/adapta.jpg
|
||||
[5]:https://www.gnome-look.org/p/1190851/
|
||||
[6]:https://i2.wp.com/itsfoss.com/wp-content/uploads/2018/03/numix.png
|
||||
[7]:https://www.gnome-look.org/p/1170667/
|
||||
[8]:https://i1.wp.com/itsfoss.com/wp-content/uploads/2018/03/hooli2.jpg
|
||||
[9]:https://www.gnome-look.org/p/1102901/
|
||||
[10]:https://i1.wp.com/itsfoss.com/wp-content/uploads/2018/03/AT.jpg
|
||||
[11]:https://itsfoss.com/ubuntu-community-theme/
|
||||
[12]:https://www.gnome-look.org/p/1215199/
|
||||
[13]:https://itsfoss.com/wp-content/uploads/2018/03/gosx-800x473.jpg
|
||||
[14]:https://www.opendesktop.org/s/Gnome/p/1171688/
|
||||
[15]:https://itsfoss.com/wp-content/uploads/2018/03/ultimatemaia-800x450.jpg
|
||||
[16]:https://www.opendesktop.org/s/Gnome/p/1193879/
|
||||
[17]:https://itsfoss.com/wp-content/uploads/2018/03/vimix-800x450.jpg
|
||||
[18]:https://www.gnome-look.org/p/1013698/
|
||||
[19]:https://itsfoss.com/wp-content/uploads/2018/03/ant-800x533.png
|
||||
[20]:https://www.opendesktop.org/p/1099856/
|
||||
[21]:https://itsfoss.com/wp-content/uploads/2018/03/flatremix-800x450.png
|
||||
[22]:https://www.opendesktop.org/p/1214931/
|
||||
[23]:https://itsfoss.com/wp-content/uploads/2018/04/paper-800x450.jpg
|
||||
[24]:https://itsfoss.com/install-paper-theme-linux/
|
||||
[25]:https://snwh.org/paper/download
|
||||
[26]:https://itsfoss.com/wp-content/uploads/2018/04/pop-800x449.jpg
|
||||
[27]:https://system76.com/
|
||||
[28]:https://itsfoss.com/system76-popos-linux/
|
||||
[29]:https://itsfoss.com/pop-os-linux-review/
|
||||
[30]:https://github.com/pop-os/gtk-theme/blob/master/README.md
|
||||
@@ -1,26 +1,28 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: (geekpi)
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: reviewer: (wxy)
|
||||
[#]: publisher: (wxy)
|
||||
[#]: url: (https://linux.cn/article-10709-1.html)
|
||||
[#]: subject: (Take to the virtual skies with FlightGear)
|
||||
[#]: via: (https://opensource.com/article/19/1/flightgear)
|
||||
[#]: author: (Don Watkins https://opensource.com/users/don-watkins)
|
||||
|
||||
使用 FlightGear 进入虚拟天空
|
||||
使用 FlightGear 翱翔天空
|
||||
======
|
||||
你梦想驾驶飞机么？试试开源飞行模拟器 FlightGear 吧。
|
||||
|
||||
> 你梦想驾驶飞机么？试试开源飞行模拟器 FlightGear 吧。
|
||||
|
||||
|
||||
|
||||
如果你曾梦想驾驶飞机，你会喜欢 [FlightGear][1] 的。它是一个功能齐全的[开源][2]飞行模拟器，可在 Linux、MacOS 和 Windows 中运行。
|
||||
|
||||
FlightGear 项目始于 1996 年，原因是对商业飞行模拟程序的不满，因为这些程序无法扩展。它的目标是创建一个复杂、强大、可扩展、开放的飞行模拟器框架，来用于学术界和飞行员培训，或者任何想要玩飞行模拟场景的人。
|
||||
FlightGear 项目始于 1996 年，原因是对商业飞行模拟程序的不满，因为这些程序无法扩展。它的目标是创建一个复杂、强大、可扩展、开放的飞行模拟器框架，来用于学术界和飞行员培训，以及任何想要玩飞行模拟场景的人。
|
||||
|
||||
### 入门
|
||||
|
||||
FlightGear 的硬件要求适中，包括支持 OpenGL 以实现平滑帧速的加速 3D 显卡。它在我的配备 i5 处理器和仅 4GB 的内存的 Linux 笔记本上运行良好。它的文档包括[在线手册][3]、一个包含[用户][5]和[开发者][6]门户的 [wiki][4]，还有大量的教程（例如它的默认飞机 [Cessna 172p][7]）教你如何操作它。
|
||||
FlightGear 的硬件要求适中，包括支持 OpenGL 以实现平滑帧速的加速 3D 显卡。它在我的配备 i5 处理器和仅 4GB 的内存的 Linux 笔记本上运行良好。它的文档包括[在线手册][3]、一个面向[用户][5]和[开发者][6]的 [wiki][4] 门户网站，还有大量的教程（例如它的默认飞机 [Cessna 172p][7]）教你如何操作它。
|
||||
|
||||
在 [Fedora][8]和 [Ubuntu][9] Linux 中很容易安装。Fedora 用户可以参考 [Fedora 安装页面][10]来运行 FlightGear。
|
||||
在 [Fedora][8] 和 [Ubuntu][9] Linux 中很容易安装。Fedora 用户可以参考 [Fedora 安装页面][10]来运行 FlightGear。
|
||||
|
||||
在 Ubuntu 18.04 中，我需要安装一个仓库：
|
||||
|
||||
@@ -42,29 +44,29 @@ $ fgfs
|
||||
|
||||
|
||||
|
||||
**Summary** 返回应用的主页面。
|
||||
“Summary” 返回应用的主页面。
|
||||
|
||||
**Aircraft** 显示你已安装的飞机，并提供了 FlightGear 的默认“机库”中安装多达 539 种其他飞机的选项。我安装了 Cessna 150L、Piper J-3 Cub 和 Bombardier CRJ-700。一些飞机（包括 CRJ-700）有教你如何驾驶商用喷气式飞机的教程。我发现这些教程内容翔实且准确。
|
||||
“Aircraft” 显示你已安装的飞机，并提供了 FlightGear 的默认“机库”中安装多达 539 种其他飞机的选项。我安装了 Cessna 150L、Piper J-3 Cub 和 Bombardier CRJ-700。一些飞机（包括 CRJ-700）有教你如何驾驶商用喷气式飞机的教程。我发现这些教程内容翔实且准确。
|
||||
|
||||
|
||||
|
||||
要选择驾驶的飞机，请将其高亮显示，然后单击菜单底部的 **Fly!**。我选择了默认的 Cessna 172p 并发现驾驶舱的刻画非常准确。
|
||||
要选择驾驶的飞机，请将其高亮显示，然后单击菜单底部的 “Fly!”。我选择了默认的 Cessna 172p 并发现驾驶舱的刻画非常准确。
|
||||
|
||||
|
||||
|
||||
默认机场是檀香山，但你在 **Location** 菜单中提供你最喜欢机场的 [ICAO 机场代码] [11]进行修改。我找到了一些小型的本地无塔机场，如 Olean 和 Dunkirk，纽约，以及包括 Buffalo，O'Hare 和 Raleigh 在内的大型机场，甚至可以选择特定的跑道。
|
||||
默认机场是檀香山，但你在 “Location” 菜单中提供你最喜欢机场的 [ICAO 机场代码] [11]进行修改。我找到了一些小型的本地无塔机场，如 Olean 和 Dunkirk，纽约，以及包括 Buffalo，O'Hare 和 Raleigh 在内的大型机场，甚至可以选择特定的跑道。
|
||||
|
||||
在 **Environment** 下，你可以调整一天中的时间、季节和天气。模拟包括高级天气建模和从 [NOAA][12] 下载当前天气的能力。
|
||||
在 “Environment” 下，你可以调整一天中的时间、季节和天气。模拟包括高级天气建模和从 [NOAA][12] 下载当前天气的能力。
|
||||
|
||||
**Settings** 提供在暂停模式中开始模拟的选项。同样在设置中，你可以选择多人模式，这样你就可以与 FlightGear 支持者的全球服务器网络上的其他玩家一起“飞行”。你必须有比较快速的互联网连接来支持此功能。
|
||||
“Settings” 提供在暂停模式中开始模拟的选项。同样在设置中，你可以选择多人模式，这样你就可以与 FlightGear 支持者的全球服务器网络上的其他玩家一起“飞行”。你必须有比较快速的互联网连接来支持此功能。
|
||||
|
||||
**Add-ons** 菜单允许你下载飞机和其他场景。
|
||||
“Add-ons” 菜单允许你下载飞机和其他场景。
|
||||
|
||||
### 开始飞行
|
||||
|
||||
为了“起飞”我的 Cessna，我使用了罗技操纵杆，它用起来不错。你可以使用顶部 **File** 菜单中的选项校准操纵杆。
|
||||
为了“起飞”我的 Cessna，我使用了罗技操纵杆，它用起来不错。你可以使用顶部 “File” 菜单中的选项校准操纵杆。
|
||||
|
||||
总的来说，我发现模拟非常准确，图形界面也很棒。你自己试下 FlightGear - 我认为你会发现它是一个非常有趣和完整的模拟软件。
|
||||
总的来说，我发现模拟非常准确，图形界面也很棒。你自己试下 FlightGear —— 我想你会发现它是一个非常有趣和完整的模拟软件。
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
@@ -73,7 +75,7 @@ via: https://opensource.com/article/19/1/flightgear
|
||||
作者：[Don Watkins][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[geekpi](https://github.com/geekpi)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
校对：[wxy](https://github.com/wxy)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
@@ -0,0 +1,348 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: (liujing97)
|
||||
[#]: reviewer: (wxy)
|
||||
[#]: publisher: (wxy)
|
||||
[#]: url: (https://linux.cn/article-10716-1.html)
|
||||
[#]: subject: (How To Understand And Identify File types in Linux)
|
||||
[#]: via: (https://www.2daygeek.com/how-to-understand-and-identify-file-types-in-linux/)
|
||||
[#]: author: (Magesh Maruthamuthu https://www.2daygeek.com/author/magesh/)
|
||||
|
||||
怎样理解和识别 Linux 中的文件类型
|
||||
======
|
||||
|
||||
众所周知，在 Linux 中一切皆为文件，包括硬盘和显卡等。在 Linux 中导航时，大部分的文件都是普通文件和目录文件。但是也有其他的类型，对应于 5 类不同的作用。因此，理解 Linux 中的文件类型在许多方面都是非常重要的。
|
||||
|
||||
如果你不相信，那只需要浏览全文，就会发现它有多重要。如果你不能理解文件类型，就不能够毫无畏惧的做任意的修改。
|
||||
|
||||
如果你做了一些错误的修改，会毁坏你的文件系统，那么当你操作的时候请小心一点。在 Linux 系统中文件是非常重要的，因为所有的设备和守护进程都被存储为文件。
|
||||
|
||||
### 在 Linux 中有多少种可用类型？
|
||||
|
||||
据我所知，在 Linux 中总共有 7 种类型的文件，分为 3 大类。具体如下。
|
||||
|
||||
* 普通文件
|
||||
* 目录文件
|
||||
* 特殊文件（该类有 5 个文件类型）
|
||||
* 链接文件
|
||||
* 字符设备文件
|
||||
* Socket 文件
|
||||
* 命名管道文件
|
||||
* 块文件
|
||||
|
||||
参考下面的表可以更好地理解 Linux 中的文件类型。
|
||||
|
||||
| 符号 | 意义 |
|
||||
| ------- | --------------------------------- |
|
||||
| `–` | 普通文件。长列表中以下划线 `_` 开头。 |
|
||||
| `d` | 目录文件。长列表中以英文字母 `d` 开头。 |
|
||||
| `l` | 链接文件。长列表中以英文字母 `l` 开头。 |
|
||||
| `c` | 字符设备文件。长列表中以英文字母 `c` 开头。 |
|
||||
| `s` | Socket 文件。长列表中以英文字母 `s` 开头。 |
|
||||
| `p` | 命名管道文件。长列表中以英文字母 `p` 开头。 |
|
||||
| `b` | 块文件。长列表中以英文字母 `b` 开头。 |
|
||||
|
||||
|
||||
### 方法１：手动识别 Linux 中的文件类型
|
||||
|
||||
如果你很了解 Linux，那么你可以借助上表很容易地识别文件类型。
|
||||
|
||||
#### 在 Linux 中如何查看普通文件？
|
||||
|
||||
在 Linux 中使用下面的命令去查看普通文件。在 Linux 文件系统中普通文件可以出现在任何地方。
|
||||
普通文件的颜色是“白色”。
|
||||
|
||||
```
|
||||
# ls -la | grep ^-
|
||||
-rw-------. 1 mageshm mageshm 1394 Jan 18 15:59 .bash_history
|
||||
-rw-r--r--. 1 mageshm mageshm 18 May 11 2012 .bash_logout
|
||||
-rw-r--r--. 1 mageshm mageshm 176 May 11 2012 .bash_profile
|
||||
-rw-r--r--. 1 mageshm mageshm 124 May 11 2012 .bashrc
|
||||
-rw-r--r--. 1 root root 26 Dec 27 17:55 liks
|
||||
-rw-r--r--. 1 root root 104857600 Jan 31 2006 test100.dat
|
||||
-rw-r--r--. 1 root root 104874307 Dec 30 2012 test100.zip
|
||||
-rw-r--r--. 1 root root 11536384 Dec 30 2012 test10.zip
|
||||
-rw-r--r--. 1 root root 61 Dec 27 19:05 test2-bzip2.txt
|
||||
-rw-r--r--. 1 root root 61 Dec 31 14:24 test3-bzip2.txt
|
||||
-rw-r--r--. 1 root root 60 Dec 27 19:01 test-bzip2.txt
|
||||
```
|
||||
|
||||
#### 在 Linux 中如何查看目录文件？
|
||||
|
||||
在 Linux 中使用下面的命令去查看目录文件。在 Linux 文件系统中目录文件可以出现在任何地方。目录文件的颜色是“蓝色”。
|
||||
|
||||
```
|
||||
# ls -la | grep ^d
|
||||
drwxr-xr-x. 3 mageshm mageshm 4096 Dec 31 14:24 links/
|
||||
drwxrwxr-x. 2 mageshm mageshm 4096 Nov 16 15:44 perl5/
|
||||
drwxr-xr-x. 2 mageshm mageshm 4096 Nov 16 15:37 public_ftp/
|
||||
drwxr-xr-x. 3 mageshm mageshm 4096 Nov 16 15:37 public_html/
|
||||
```
|
||||
|
||||
#### 在 Linux 中如何查看链接文件？
|
||||
|
||||
在 Linux 中使用下面的命令去查看链接文件。在 Linux 文件系统中链接文件可以出现在任何地方。
|
||||
链接文件有两种可用类型，软连接和硬链接。链接文件的颜色是“浅绿宝石色”。
|
||||
|
||||
```
|
||||
# ls -la | grep ^l
|
||||
lrwxrwxrwx. 1 root root 31 Dec 7 15:11 s-link-file -> /links/soft-link/test-soft-link
|
||||
lrwxrwxrwx. 1 root root 38 Dec 7 15:12 s-link-folder -> /links/soft-link/test-soft-link-folder
|
||||
```
|
||||
|
||||
#### 在 Linux 中如何查看字符设备文件？
|
||||
|
||||
在 Linux 中使用下面的命令查看字符设备文件。字符设备文件仅出现在特定位置。它出现在目录 `/dev` 下。字符设备文件的颜色是“黄色”。
|
||||
|
||||
```
|
||||
# ls -la | grep ^c
|
||||
# ls -la | grep ^c
|
||||
crw-------. 1 root root 5, 1 Jan 28 14:05 console
|
||||
crw-rw----. 1 root root 10, 61 Jan 28 14:05 cpu_dma_latency
|
||||
crw-rw----. 1 root root 10, 62 Jan 28 14:05 crash
|
||||
crw-rw----. 1 root root 29, 0 Jan 28 14:05 fb0
|
||||
crw-rw-rw-. 1 root root 1, 7 Jan 28 14:05 full
|
||||
crw-rw-rw-. 1 root root 10, 229 Jan 28 14:05 fuse
|
||||
```
|
||||
|
||||
#### 在 Linux 中如何查看块文件？
|
||||
|
||||
在 Linux 中使用下面的命令查看块文件。块文件仅出现在特定位置。它出现在目录 `/dev` 下。块文件的颜色是“黄色”。
|
||||
|
||||
```
|
||||
# ls -la | grep ^b
|
||||
brw-rw----. 1 root disk 7, 0 Jan 28 14:05 loop0
|
||||
brw-rw----. 1 root disk 7, 1 Jan 28 14:05 loop1
|
||||
brw-rw----. 1 root disk 7, 2 Jan 28 14:05 loop2
|
||||
brw-rw----. 1 root disk 7, 3 Jan 28 14:05 loop3
|
||||
brw-rw----. 1 root disk 7, 4 Jan 28 14:05 loop4
|
||||
```
|
||||
|
||||
#### 在 Linux 中如何查看 Socket 文件？
|
||||
|
||||
在 Linux 中使用下面的命令查看 Socket 文件。Socket 文件可以出现在任何地方。Scoket 文件的颜色是“粉色”。（LCTT 译注：此处及下面关于 Socket 文件、命名管道文件可出现的位置原文描述有误，已修改。）
|
||||
|
||||
```
|
||||
# ls -la | grep ^s
|
||||
srw-rw-rw- 1 root root 0 Jan 5 16:36 system_bus_socket
|
||||
```
|
||||
|
||||
#### 在 Linux 中如何查看命名管道文件？
|
||||
|
||||
在 Linux 中使用下面的命令查看命名管道文件。命名管道文件可以出现在任何地方。命名管道文件的颜色是“黄色”。
|
||||
|
||||
```
|
||||
# ls -la | grep ^p
|
||||
prw-------. 1 root root 0 Jan 28 14:06 replication-notify-fifo|
|
||||
prw-------. 1 root root 0 Jan 28 14:06 stats-mail|
|
||||
```
|
||||
|
||||
### 方法２：在 Linux 中如何使用 file 命令识别文件类型
|
||||
|
||||
在 Linux 中 `file` 命令允许我们去确定不同的文件类型。这里有三个测试集，按此顺序进行三组测试：文件系统测试、魔术字节测试和用于识别文件类型的语言测试。
|
||||
|
||||
#### 在 Linux 中如何使用 file 命令查看普通文件
|
||||
|
||||
在你的终端简单地输入 `file` 命令跟着普通文件。`file` 命令将会读取提供的文件内容并且准确地显示文件的类型。
|
||||
|
||||
这就是我们看到对于每个普通文件有不同结果的原因。参考下面普通文件的不同结果。
|
||||
|
||||
```
|
||||
# file 2daygeek_access.log
|
||||
2daygeek_access.log: ASCII text, with very long lines
|
||||
|
||||
# file powertop.html
|
||||
powertop.html: HTML document, ASCII text, with very long lines
|
||||
|
||||
# file 2g-test
|
||||
2g-test: JSON data
|
||||
|
||||
# file powertop.txt
|
||||
powertop.txt: HTML document, UTF-8 Unicode text, with very long lines
|
||||
|
||||
# file 2g-test-05-01-2019.tar.gz
|
||||
2g-test-05-01-2019.tar.gz: gzip compressed data, last modified: Sat Jan 5 18:22:20 2019, from Unix, original size 450560
|
||||
```
|
||||
|
||||
#### 在 Linux 中如何使用 file 命令查看目录文件？
|
||||
|
||||
在你的终端简单地输入 `file` 命令跟着目录。参阅下面的结果。
|
||||
|
||||
```
|
||||
# file Pictures/
|
||||
Pictures/: directory
|
||||
```
|
||||
|
||||
#### 在 Linux 中如何使用 file 命令查看链接文件？
|
||||
|
||||
在你的终端简单地输入 `file` 命令跟着链接文件。参阅下面的结果。
|
||||
|
||||
```
|
||||
# file log
|
||||
log: symbolic link to /run/systemd/journal/dev-log
|
||||
```
|
||||
|
||||
#### 在 Linux 中如何使用 file 命令查看字符设备文件？
|
||||
|
||||
在你的终端简单地输入 `file` 命令跟着字符设备文件。参阅下面的结果。
|
||||
|
||||
```
|
||||
# file vcsu
|
||||
vcsu: character special (7/64)
|
||||
```
|
||||
|
||||
#### 在 Linux 中如何使用 file 命令查看块文件？
|
||||
|
||||
在你的终端简单地输入 `file` 命令跟着块文件。参阅下面的结果。
|
||||
|
||||
```
|
||||
# file sda1
|
||||
sda1: block special (8/1)
|
||||
```
|
||||
|
||||
#### 在 Linux 中如何使用 file 命令查看 Socket 文件？
|
||||
|
||||
在你的终端简单地输入 `file` 命令跟着 Socket 文件。参阅下面的结果。
|
||||
|
||||
```
|
||||
# file system_bus_socket
|
||||
system_bus_socket: socket
|
||||
```
|
||||
|
||||
#### 在 Linux 中如何使用 file 命令查看命名管道文件？
|
||||
|
||||
在你的终端简单地输入 `file` 命令跟着命名管道文件。参阅下面的结果。
|
||||
|
||||
```
|
||||
# file pipe-test
|
||||
pipe-test: fifo (named pipe)
|
||||
```
|
||||
|
||||
### 方法 3：在 Linux 中如何使用 stat 命令识别文件类型？
|
||||
|
||||
`stat` 命令允许我们去查看文件类型或文件系统状态。该实用程序比 `file` 命令提供更多的信息。它显示文件的大量信息，例如大小、块大小、IO 块大小、Inode 值、链接、文件权限、UID、GID、文件的访问/更新和修改的时间等详细信息。
|
||||
|
||||
#### 在 Linux 中如何使用 stat 命令查看普通文件？
|
||||
|
||||
在你的终端简单地输入 `stat` 命令跟着普通文件。参阅下面的结果。
|
||||
|
||||
```
|
||||
# stat 2daygeek_access.log
|
||||
File: 2daygeek_access.log
|
||||
Size: 14406929 Blocks: 28144 IO Block: 4096 regular file
|
||||
Device: 10301h/66305d Inode: 1727555 Links: 1
|
||||
Access: (0644/-rw-r--r--) Uid: ( 1000/ daygeek) Gid: ( 1000/ daygeek)
|
||||
Access: 2019-01-03 14:05:26.430328867 +0530
|
||||
Modify: 2019-01-03 14:05:26.460328868 +0530
|
||||
Change: 2019-01-03 14:05:26.460328868 +0530
|
||||
Birth: -
|
||||
```
|
||||
|
||||
#### 在 Linux 中如何使用 stat 命令查看目录文件？
|
||||
|
||||
在你的终端简单地输入 `stat` 命令跟着目录文件。参阅下面的结果。
|
||||
|
||||
```
|
||||
# stat Pictures/
|
||||
File: Pictures/
|
||||
Size: 4096 Blocks: 8 IO Block: 4096 directory
|
||||
Device: 10301h/66305d Inode: 1703982 Links: 3
|
||||
Access: (0755/drwxr-xr-x) Uid: ( 1000/ daygeek) Gid: ( 1000/ daygeek)
|
||||
Access: 2018-11-24 03:22:11.090000828 +0530
|
||||
Modify: 2019-01-05 18:27:01.546958817 +0530
|
||||
Change: 2019-01-05 18:27:01.546958817 +0530
|
||||
Birth: -
|
||||
```
|
||||
|
||||
#### 在 Linux 中如何使用 stat 命令查看链接文件？
|
||||
|
||||
在你的终端简单地输入 `stat` 命令跟着链接文件。参阅下面的结果。
|
||||
|
||||
```
|
||||
# stat /dev/log
|
||||
File: /dev/log -> /run/systemd/journal/dev-log
|
||||
Size: 28 Blocks: 0 IO Block: 4096 symbolic link
|
||||
Device: 6h/6d Inode: 278 Links: 1
|
||||
Access: (0777/lrwxrwxrwx) Uid: ( 0/ root) Gid: ( 0/ root)
|
||||
Access: 2019-01-05 16:36:31.033333447 +0530
|
||||
Modify: 2019-01-05 16:36:30.766666768 +0530
|
||||
Change: 2019-01-05 16:36:30.766666768 +0530
|
||||
Birth: -
|
||||
```
|
||||
|
||||
#### 在 Linux 中如何使用 stat 命令查看字符设备文件？
|
||||
|
||||
在你的终端简单地输入 `stat` 命令跟着字符设备文件。参阅下面的结果。
|
||||
|
||||
```
|
||||
# stat /dev/vcsu
|
||||
File: /dev/vcsu
|
||||
Size: 0 Blocks: 0 IO Block: 4096 character special file
|
||||
Device: 6h/6d Inode: 16 Links: 1 Device type: 7,40
|
||||
Access: (0660/crw-rw----) Uid: ( 0/ root) Gid: ( 5/ tty)
|
||||
Access: 2019-01-05 16:36:31.056666781 +0530
|
||||
Modify: 2019-01-05 16:36:31.056666781 +0530
|
||||
Change: 2019-01-05 16:36:31.056666781 +0530
|
||||
Birth: -
|
||||
```
|
||||
|
||||
#### 在 Linux 中如何使用 stat 命令查看块文件？
|
||||
|
||||
在你的终端简单地输入 `stat` 命令跟着块文件。参阅下面的结果。
|
||||
|
||||
```
|
||||
# stat /dev/sda1
|
||||
File: /dev/sda1
|
||||
Size: 0 Blocks: 0 IO Block: 4096 block special file
|
||||
Device: 6h/6d Inode: 250 Links: 1 Device type: 8,1
|
||||
Access: (0660/brw-rw----) Uid: ( 0/ root) Gid: ( 994/ disk)
|
||||
Access: 2019-01-05 16:36:31.596666806 +0530
|
||||
Modify: 2019-01-05 16:36:31.596666806 +0530
|
||||
Change: 2019-01-05 16:36:31.596666806 +0530
|
||||
Birth: -
|
||||
```
|
||||
|
||||
#### 在 Linux 中如何使用 stat 命令查看 Socket 文件？
|
||||
|
||||
在你的终端简单地输入 `stat` 命令跟着 Socket 文件。参阅下面的结果。
|
||||
|
||||
```
|
||||
# stat /var/run/dbus/system_bus_socket
|
||||
File: /var/run/dbus/system_bus_socket
|
||||
Size: 0 Blocks: 0 IO Block: 4096 socket
|
||||
Device: 15h/21d Inode: 576 Links: 1
|
||||
Access: (0666/srw-rw-rw-) Uid: ( 0/ root) Gid: ( 0/ root)
|
||||
Access: 2019-01-05 16:36:31.823333482 +0530
|
||||
Modify: 2019-01-05 16:36:31.810000149 +0530
|
||||
Change: 2019-01-05 16:36:31.810000149 +0530
|
||||
Birth: -
|
||||
```
|
||||
|
||||
#### 在 Linux 中如何使用 stat 命令查看命名管道文件？
|
||||
|
||||
在你的终端简单地输入 `stat` 命令跟着命名管道文件。参阅下面的结果。
|
||||
|
||||
```
|
||||
# stat pipe-test
|
||||
File: pipe-test
|
||||
Size: 0 Blocks: 0 IO Block: 4096 fifo
|
||||
Device: 10301h/66305d Inode: 1705583 Links: 1
|
||||
Access: (0644/prw-r--r--) Uid: ( 1000/ daygeek) Gid: ( 1000/ daygeek)
|
||||
Access: 2019-01-06 02:00:03.040394731 +0530
|
||||
Modify: 2019-01-06 02:00:03.040394731 +0530
|
||||
Change: 2019-01-06 02:00:03.040394731 +0530
|
||||
Birth: -
|
||||
```
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.2daygeek.com/how-to-understand-and-identify-file-types-in-linux/
|
||||
|
||||
作者：[Magesh Maruthamuthu][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[liujing97](https://github.com/liujing97)
|
||||
校对：[wxy](https://github.com/wxy)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://www.2daygeek.com/author/magesh/
|
||||
[b]: https://github.com/lujun9972
|
||||
@@ -0,0 +1,153 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: (liujing97)
|
||||
[#]: reviewer: (wxy)
|
||||
[#]: publisher: (wxy)
|
||||
[#]: url: (https://linux.cn/article-10727-1.html)
|
||||
[#]: subject: (7 Methods To Identify Disk Partition/FileSystem UUID On Linux)
|
||||
[#]: via: (https://www.2daygeek.com/check-partitions-uuid-filesystem-uuid-universally-unique-identifier-linux/)
|
||||
[#]: author: (Magesh Maruthamuthu https://www.2daygeek.com/author/magesh/)
|
||||
|
||||
Linux 中获取硬盘分区或文件系统的 UUID 的七种方法
|
||||
======
|
||||
|
||||
作为一个 Linux 系统管理员，你应该知道如何去查看分区的 UUID 或文件系统的 UUID。因为现在大多数的 Linux 系统都使用 UUID 挂载分区。你可以在 `/etc/fstab` 文件中可以验证。
|
||||
|
||||
有许多可用的实用程序可以查看 UUID。本文我们将会向你展示多种查看 UUID 的方法，并且你可以选择一种适合于你的方法。
|
||||
|
||||
### 何为 UUID？
|
||||
|
||||
UUID 意即<ruby>通用唯一识别码<rt>Universally Unique Identifier</rt></ruby>，它可以帮助 Linux 系统识别一个磁盘分区而不是块设备文件。
|
||||
|
||||
自内核 2.15.1 起，libuuid 就是 util-linux-ng 包中的一部分，它被默认安装在 Linux 系统中。UUID 由该库生成，可以合理地认为在一个系统中 UUID 是唯一的，并且在所有系统中也是唯一的。
|
||||
|
||||
这是在计算机系统中用来标识信息的一个 128 位（比特）的数字。UUID 最初被用在<ruby>阿波罗网络计算机系统<rt>Apollo Network Computing System</rt></ruby>（NCS）中，之后 UUID 被<ruby>开放软件基金会<rt>Open Software Foundation</rt></ruby>（OSF）标准化，成为<ruby>分布式计算环境<rt>Distributed Computing Environment</rt></ruby>（DCE）的一部分。
|
||||
|
||||
UUID 以 32 个十六进制的数字表示，被连字符分割为 5 组显示，总共的 36 个字符的格式为 8-4-4-4-12（32 个字母或数字和 4 个连字符）。
|
||||
|
||||
例如： `d92fa769-e00f-4fd7-b6ed-ecf7224af7fa`
|
||||
|
||||
我的 `/etc/fstab` 文件示例：
|
||||
|
||||
```
|
||||
# cat /etc/fstab
|
||||
|
||||
# /etc/fstab: static file system information.
|
||||
#
|
||||
# Use 'blkid' to print the universally unique identifier for a device; this may
|
||||
# be used with UUID= as a more robust way to name devices that works even if
|
||||
# disks are added and removed. See fstab(5).
|
||||
#
|
||||
#
|
||||
UUID=69d9dd18-36be-4631-9ebb-78f05fe3217f / ext4 defaults,noatime 0 1
|
||||
UUID=a2092b92-af29-4760-8e68-7a201922573b swap swap defaults,noatime 0 2
|
||||
```
|
||||
|
||||
我们可以使用下面的 7 个命令来查看。
|
||||
|
||||
* `blkid` 命令：定位或打印块设备的属性。
|
||||
* `lsblk` 命令：列出所有可用的或指定的块设备的信息。
|
||||
* `hwinfo` 命令：硬件信息工具，是另外一个很好的实用工具，用于查询系统中已存在硬件。
|
||||
* `udevadm` 命令：udev 管理工具
|
||||
* `tune2fs` 命令：调整 ext2/ext3/ext4 文件系统上的可调文件系统参数。
|
||||
* `dumpe2fs` 命令：查询 ext2/ext3/ext4 文件系统的信息。
|
||||
* 使用 `by-uuid` 路径：该目录下包含有 UUID 和实际的块设备文件，UUID 与实际的块设备文件链接在一起。
|
||||
|
||||
### Linux 中如何使用 blkid 命令查看磁盘分区或文件系统的 UUID？
|
||||
|
||||
`blkid` 是定位或打印块设备属性的命令行实用工具。它利用 libblkid 库在 Linux 系统中获得到磁盘分区的 UUID。
|
||||
|
||||
```
|
||||
# blkid
|
||||
/dev/sda1: UUID="d92fa769-e00f-4fd7-b6ed-ecf7224af7fa" TYPE="ext4" PARTUUID="eab59449-01"
|
||||
/dev/sdc1: UUID="d17e3c31-e2c9-4f11-809c-94a549bc43b7" TYPE="ext2" PARTUUID="8cc8f9e5-01"
|
||||
/dev/sdc3: UUID="ca307aa4-0866-49b1-8184-004025789e63" TYPE="ext4" PARTUUID="8cc8f9e5-03"
|
||||
/dev/sdc5: PARTUUID="8cc8f9e5-05"
|
||||
```
|
||||
|
||||
### Linux 中如何使用 lsblk 命令查看磁盘分区或文件系统的 UUID？
|
||||
|
||||
`lsblk` 列出所有有关可用或指定块设备的信息。`lsblk` 命令读取 sysfs 文件系统和 udev 数据库以收集信息。
|
||||
|
||||
如果 udev 数据库不可用或者编译的 lsblk 不支持 udev，它会试图从块设备中读取卷标、UUID 和文件系统类型。这种情况下，必须以 root 身份运行。该命令默认会以类似于树的格式打印出所有的块设备（RAM 盘除外）。
|
||||
|
||||
```
|
||||
# lsblk -o name,mountpoint,size,uuid
|
||||
NAME MOUNTPOINT SIZE UUID
|
||||
sda 30G
|
||||
└─sda1 / 20G d92fa769-e00f-4fd7-b6ed-ecf7224af7fa
|
||||
sdb 10G
|
||||
sdc 10G
|
||||
├─sdc1 1G d17e3c31-e2c9-4f11-809c-94a549bc43b7
|
||||
├─sdc3 1G ca307aa4-0866-49b1-8184-004025789e63
|
||||
├─sdc4 1K
|
||||
└─sdc5 1G
|
||||
sdd 10G
|
||||
sde 10G
|
||||
sr0 1024M
|
||||
```
|
||||
|
||||
### Linux 中如何使用 by-uuid 路径查看磁盘分区或文件系统的 UUID？
|
||||
|
||||
该目录包含了 UUID 和实际的块设备文件，UUID 与实际的块设备文件链接在一起。
|
||||
|
||||
```
|
||||
# ls -lh /dev/disk/by-uuid/
|
||||
total 0
|
||||
lrwxrwxrwx 1 root root 10 Jan 29 08:34 ca307aa4-0866-49b1-8184-004025789e63 -> ../../sdc3
|
||||
lrwxrwxrwx 1 root root 10 Jan 29 08:34 d17e3c31-e2c9-4f11-809c-94a549bc43b7 -> ../../sdc1
|
||||
lrwxrwxrwx 1 root root 10 Jan 29 08:34 d92fa769-e00f-4fd7-b6ed-ecf7224af7fa -> ../../sda1
|
||||
```
|
||||
|
||||
### Linux 中如何使用 hwinfo 命令查看磁盘分区或文件系统的 UUID？
|
||||
|
||||
[hwinfo][1] 意即硬件信息工具，是另外一种很好的实用工具。它被用来检测系统中已存在的硬件，并且以可读的格式显示各种硬件组件的细节信息。
|
||||
|
||||
```
|
||||
# hwinfo --block | grep by-uuid | awk '{print $3,$7}'
|
||||
/dev/sdc1, /dev/disk/by-uuid/d17e3c31-e2c9-4f11-809c-94a549bc43b7
|
||||
/dev/sdc3, /dev/disk/by-uuid/ca307aa4-0866-49b1-8184-004025789e63
|
||||
/dev/sda1, /dev/disk/by-uuid/d92fa769-e00f-4fd7-b6ed-ecf7224af7fa
|
||||
```
|
||||
|
||||
### Linux 中如何使用 udevadm 命令查看磁盘分区或文件系统的 UUID？
|
||||
|
||||
`udevadm` 需要命令和命令特定的操作。它控制 systemd-udevd 的运行时行为，请求内核事件、管理事件队列并且提供简单的调试机制。
|
||||
|
||||
```
|
||||
# udevadm info -q all -n /dev/sdc1 | grep -i by-uuid | head -1
|
||||
S: disk/by-uuid/d17e3c31-e2c9-4f11-809c-94a549bc43b7
|
||||
```
|
||||
|
||||
### Linux 中如何使用 tune2fs 命令查看磁盘分区或文件系统的 UUID？
|
||||
|
||||
`tune2fs` 允许系统管理员在 Linux 的 ext2、ext3、ext4 文件系统中调整各种可调的文件系统参数。这些选项的当前值可以使用选项 `-l` 显示。
|
||||
|
||||
```
|
||||
# tune2fs -l /dev/sdc1 | grep UUID
|
||||
Filesystem UUID: d17e3c31-e2c9-4f11-809c-94a549bc43b7
|
||||
```
|
||||
|
||||
### Linux 中如何使用 dumpe2fs 命令查看磁盘分区或文件系统的 UUID？
|
||||
|
||||
`dumpe2fs` 打印出现在设备文件系统中的超级块和块组的信息。
|
||||
|
||||
```
|
||||
# dumpe2fs /dev/sdc1 | grep UUID
|
||||
dumpe2fs 1.43.5 (04-Aug-2017)
|
||||
Filesystem UUID: d17e3c31-e2c9-4f11-809c-94a549bc43b7
|
||||
```
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.2daygeek.com/check-partitions-uuid-filesystem-uuid-universally-unique-identifier-linux/
|
||||
|
||||
作者：[Magesh Maruthamuthu][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[liujing97](https://github.com/liujing97)
|
||||
校对：[wxy](https://github.com/wxy)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://www.2daygeek.com/author/magesh/
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://www.2daygeek.com/hwinfo-check-display-detect-system-hardware-information-linux/
|
||||
@@ -0,0 +1,74 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: (geekpi)
|
||||
[#]: reviewer: (wxy)
|
||||
[#]: publisher: (wxy)
|
||||
[#]: url: (https://linux.cn/article-10723-1.html)
|
||||
[#]: subject: (Ubuntu 14.04 is Reaching the End of Life. Here are Your Options)
|
||||
[#]: via: (https://itsfoss.com/ubuntu-14-04-end-of-life/)
|
||||
[#]: author: (Abhishek Prakash https://itsfoss.com/author/abhishek/)
|
||||
|
||||
Ubuntu 14.04 即将结束支持，你该怎么办？
|
||||
======
|
||||
|
||||
Ubuntu 14.04 即将于 2019 年 4 月 30 日结束支持。这意味着在此日期之后 Ubuntu 14.04 用户将无法获得安全和维护更新。
|
||||
|
||||
你甚至不会获得已安装应用的更新，并且不手动修改 `sources.list` 则无法使用 `apt` 命令或软件中心安装新应用。
|
||||
|
||||
Ubuntu 14.04 大约在五年前发布。这是 Ubuntu 长期支持版本（LTS）。
|
||||
|
||||
[检查 Ubuntu 版本][1]并查看你是否仍在使用 Ubuntu 14.04。如果是桌面或服务器版，你可能想知道在这种情况下你应该怎么做。
|
||||
|
||||
我来帮助你。告诉你在这种情况下你有些什么选择。
|
||||
|
||||
![][2]
|
||||
|
||||
### 升级到 Ubuntu 16.04 LTS（最简单的方式）
|
||||
|
||||
如果你可以连接互联网，你可以从 Ubuntu 14.04 升级到 Ubuntu 16.04 LTS。
|
||||
|
||||
Ubuntu 16.04 也是一个长期支持版本，它将支持到 2021 年 4 月。这意味着下次升级前你还有两年的时间。
|
||||
|
||||
我建议阅读这个[升级 Ubuntu 版本][3]的教程。它最初是为了将 Ubuntu 16.04 升级到 Ubuntu 18.04 而编写的，但这些步骤也适用于你的情况。
|
||||
|
||||
### 做好备份，全新安装 Ubuntu 18.04 LTS（非常适合桌面用户）
|
||||
|
||||
另一个选择是备份你的文档、音乐、图片、下载和其他任何你不想丢失数据的文件夹。
|
||||
|
||||
我说的备份指的是将这些文件夹复制到外部 USB 盘。换句话说，你应该有办法将数据复制回计算机，因为你将格式化你的系统。
|
||||
|
||||
我建议桌面用户使用此选项。Ubuntu 18.04 是目前的长期支持版本，它将至少在 2023 年 4 月之前得到支持。在你被迫进行下次升级之前，你将有四年的时间。
|
||||
|
||||
### 支付扩展安全维护费用并继续使用 Ubuntu 14.04
|
||||
|
||||
这适用于企业客户。Canonical 是 Ubuntu 的母公司，它提供 Ubuntu Advantage 计划，客户可以支付电话电子邮件支持和其他益处。
|
||||
|
||||
Ubuntu Advantage 计划用户还有[扩展安全维护][4]（ESM）功能。即使给定版本的生命周期结束后，此计划也会提供安全更新。
|
||||
|
||||
这需要付出金钱。服务器用户每个物理节点每年花费 225 美元。对于桌面用户，价格为每年 150 美元。你可以在[此处][5]了解 Ubuntu Advantage 计划的详细定价。
|
||||
|
||||
### 还在使用 Ubuntu 14.04 吗？
|
||||
|
||||
如果你还在使用 Ubuntu 14.04，那么你应该开始了解这些选择，因为你还有不到一个月的时间。
|
||||
|
||||
在任何情况下，你都不能在 2019 年 4 月 30 日之后使用 Ubuntu 14.04，因为你的系统由于缺乏安全更新而容易受到攻击。无法安装新应用将是一个额外的痛苦。
|
||||
|
||||
那么，你会做什么选择？升级到 Ubuntu 16.04 或 18.04 或付费 ESM？
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://itsfoss.com/ubuntu-14-04-end-of-life/
|
||||
|
||||
作者：[Abhishek Prakash][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[geekpi](https://github.com/geekpi)
|
||||
校对：[wxy](https://github.com/wxy)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://itsfoss.com/author/abhishek/
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://itsfoss.com/how-to-know-ubuntu-unity-version/
|
||||
[2]: https://i1.wp.com/itsfoss.com/wp-content/uploads/2019/02/ubuntu-14-04-end-of-life-featured.png?resize=800%2C450&ssl=1
|
||||
[3]: https://itsfoss.com/upgrade-ubuntu-version/
|
||||
[4]: https://www.ubuntu.com/esm
|
||||
[5]: https://www.ubuntu.com/support/plans-and-pricing
|
||||
@@ -1,41 +1,42 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: (geekpi)
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: reviewer: (wxy)
|
||||
[#]: publisher: (wxy)
|
||||
[#]: url: (https://linux.cn/article-10707-1.html)
|
||||
[#]: subject: (7 resources for learning to use your Raspberry Pi)
|
||||
[#]: via: (https://opensource.com/article/19/3/resources-raspberry-pi)
|
||||
[#]: author: (Manuel Dewald https://opensource.com/users/ntlx)
|
||||
|
||||
学习使用树莓派的 7 个资源
|
||||
======
|
||||
缩短树莓派学习曲线的书籍、课程和网站。
|
||||
|
||||
> 一些缩短树莓派学习曲线的书籍、课程和网站。
|
||||
|
||||
|
||||
|
||||
[树莓派][1]是一款小型单板计算机，最初用于教学和学习编程和计算机科学。但如今它有更多用处。它是一种经济、低功耗计算机，人们将它用于各种各样的事情 - 从家庭娱乐到服务器应用，再到物联网 （IoT） 项目。
|
||||
[树莓派][1]是一款小型单板计算机，最初用于教学和学习编程和计算机科学。但如今它有更多用处。它是一种经济的低功耗计算机，人们将它用于各种各样的事情 —— 从家庭娱乐到服务器应用，再到物联网（IoT） 项目。
|
||||
|
||||
关于这个主题有很多资源，你可以做很多不同的项目，很难知道从哪里开始。以下是一些资源，可以帮助你开始使用树莓派。愉快地浏览，但不要停留在这里。到处看下，深入下去你就会发现树莓派的新世界。
|
||||
关于这个主题有很多资源，你可以做很多不同的项目，却很难知道从哪里开始。以下是一些资源，可以帮助你开始使用树莓派。看看这篇文章，但不要满足于此。到处看下，深入下去你就会发现树莓派的新世界。
|
||||
|
||||
### 书籍
|
||||
|
||||
关于树莓派有很多不同语言的书籍。这两本将帮助你开始了解，然后深入了解树莓派。
|
||||
关于树莓派有很多不同语言的书籍。这两本书将帮助你开始了解，然后深入了解树莓派。
|
||||
|
||||
#### 由 Simon Monk 编写的 Raspberry Pi Cookbook：软件和硬件问题及解决方案
|
||||
#### 由 Simon Monk 编写的《树莓派手边书：软件和硬件问题及解决方案》
|
||||
|
||||
Simon Monk 是一名软件工程师，并且多年来一直是手工业余爱好者。他最初被 Arduino 这块易于使用的开发板所吸引，后来出版了一本关于它的[书][2]。后来，他开始使用树莓派并写了 [Raspberry Pi Cookbook：软件和硬件问题和解决方案][3]这本书。在本书中，你可以找到大量树莓派项目的最佳时间，以及你可能面对的各种挑战的解决方案。
|
||||
Simon Monk 是一名软件工程师，并且多年来一直是业余手工爱好者。他最初被 Arduino 这块易于使用的开发板所吸引，后来出版了一本关于它的[书][2]。后来，他开始使用树莓派并写了《[树莓派手边书：软件和硬件问题和解决方案][3]》这本书。在本书中，你可以找到大量树莓派项目的最佳时间，以及你可能面对的各种挑战的解决方案。
|
||||
|
||||
####由 Simon Monk 编写的树莓派编程：从 Python 入门
|
||||
#### 由 Simon Monk 编写的《树莓派编程：从 Python 入门》
|
||||
|
||||
Python 已经发展成为开始树莓派项目的首选编程语言，因为它易于学习和使用，即使你没有任何编程经验。此外，它的许多库可以帮助你专注于使你的项目变得特别，而不是实现协议反复地与传感器不断通信。Monk 在 Raspberry Pi Cookbook 中写了两章关于 Python 编程，但[树莓派编程：从 Python 入门][4]是一个更全面的快速入门。它向你介绍了 Python，并向你展示了可以在树莓派上使用它创建的一些项目。
|
||||
Python 已经发展成为开始一个树莓派项目的首选编程语言，因为它易于学习和使用，即使你没有任何编程经验。此外，它的许多库可以帮助你专注于使你的项目变得特别，而不是实现协议以与传感器反复通信。Monk 在《树莓派手边书》中写了两章关于 Python 编程，但《[树莓派编程：从 Python 入门][4]》是一个更全面的快速入门。它向你介绍了 Python，并向你展示了可以在树莓派上使用它创建的一些项目。
|
||||
|
||||
### 在线课程
|
||||
|
||||
新的树莓派用户可以选择许多在线课程和教程，包括这个入门课程。
|
||||
|
||||
#### Raspberry Pi Class
|
||||
|
||||
Instructables 的免费 [Raspberry Pi Class][5] 在线课程提供了对树莓派的全面介绍。它从树莓派和 Linux 操作基础开始，然后进入 Python 编程和 GPIO 通信。如果你是这方面的新手，并希望快速入门，这使它成为一个很好的从上到下的树莓派指南。
|
||||
#### 树莓派课程
|
||||
|
||||
Instructables 免费的在线[树莓派课程][5]提供了对树莓派的全面介绍。它从树莓派和 Linux 操作基础开始，然后进入 Python 编程和 GPIO 通信。如果你是这方面的新手，并希望快速入门，这使它成为一个很好的自上而下的树莓派指南。
|
||||
|
||||
### 网站
|
||||
|
||||
@@ -43,7 +44,7 @@ Instructables 的免费 [Raspberry Pi Class][5] 在线课程提供了对树莓
|
||||
|
||||
#### RaspberryPi.org
|
||||
|
||||
官方的[树莓派][6]网站是最好的入门之一。许多关于特定项目的文章有链接到基础知识的链接，如将 Raspbian 安装到树莓派上。 （这是我倾向的，而不是在每个操作中重复说明。）你还可以找到学生技术[教育][8]方面的[示例项目][7]和课程。
|
||||
官方的[树莓派][6]网站是最好的入门之一。有许多关于特定项目的文章会链接到这里的基础知识，如将 Raspbian 安装到树莓派上。（这是我倾向的做法，而不是在每篇文章中重复说明。）你还可以找到学生技术[教育][8]方面的[示例项目][7]和课程。
|
||||
|
||||
#### Opensource.com
|
||||
|
||||
@@ -51,7 +52,7 @@ Instructables 的免费 [Raspberry Pi Class][5] 在线课程提供了对树莓
|
||||
|
||||
#### Instructables 和 Hackaday
|
||||
|
||||
你想造自己的复古街机么？或者在镜子上显示当天的天气信息、时间和第一事务？你是否想要为派对创建一个文字时钟或者相簿？你可以在 [Instructables][10] 和 [Hackaday][11] 这样的网站上找到如何使用树莓派完成所有这些（以及更多！）的说明。如果你不确定是否要买树莓派，请浏览这些网站，你会发现有很多理由可以购买。
|
||||
你想造自己的复古街机么？或者在镜子上显示当天的天气信息、时间和第一事务？你是否想要为派对创建一个文字时钟或者相簿？你可以在 [Instructables][10] 和 [Hackaday][11] 这样的网站上找到如何使用树莓派完成所有这些（以及更多！）的说明。如果你不确定是否要买树莓派，请浏览这些网站，你会发现有很多理由值得购买。
|
||||
|
||||
你最喜欢的树莓派资源是什么？请在评论中分享！
|
||||
|
||||
@@ -62,7 +63,7 @@ via: https://opensource.com/article/19/3/resources-raspberry-pi
|
||||
作者：[Manuel Dewald][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[geekpi](https://github.com/geekpi)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
校对：[wxy](https://github.com/wxy)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
@@ -1,19 +1,20 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: (geekpi)
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: reviewer: (wxy)
|
||||
[#]: publisher: (wxy)
|
||||
[#]: url: (https://linux.cn/article-10711-1.html)
|
||||
[#]: subject: (Do advanced math with Mathematica on the Raspberry Pi)
|
||||
[#]: via: (https://opensource.com/article/19/3/do-math-raspberry-pi)
|
||||
[#]: author: (Anderson Silva https://opensource.com/users/ansilva)
|
||||
|
||||
在树莓派上使用 Mathematica 进行高级数学运算
|
||||
树莓派使用入门：在树莓派上使用 Mathematica 进行高级数学运算
|
||||
======
|
||||
Wolfram 将一个版本 Mathematica 捆绑到了 Raspbian 中。在我们关于树莓派入门系列的第 12 篇文章中学习如何使用它。
|
||||
|
||||
> Wolfram 在 Raspbian 中捆绑了一个版本的 Mathematica。在我们的树莓派入门系列的第 12 篇文章中将学习如何使用它。
|
||||
|
||||
|
||||
|
||||
在 90 年代中期，我进入了大学数学专业，即使我以计算机科学学位毕业，第二专业数学我已经上了足够的课程，但还有两门小课没有上。当时，我被介绍了 [Wolfram][2] 中一个名为[Mathematica][1] 的应用，我们可以将黑板上的许多代数和微分方程输入计算机。我每月花几个小时在实验室学习 Wolfram 语言并在 Mathematica 上解决积分等问题。
|
||||
在 90 年代中期，我进入了大学数学专业，虽然我是以计算机科学学位毕业的，但是我就差两门课程就拿到了双学位，包括数学专业的学位。当时，我接触到了 [Wolfram][2] 的一个名为 [Mathematica][1] 的应用，我们可以将黑板上的许多代数和微分方程输入计算机。我每月花几个小时在实验室学习 Wolfram 语言，并在 Mathematica 上解决积分等问题。
|
||||
|
||||
对于大学生来说 Mathematica 是闭源而且昂贵的，因此在差不多 20 年后，看到 Wolfram 将一个版本的 Mathematica 与 Raspbian 和 Raspberry Pi 捆绑在一起是一个惊喜。如果你决定使用另一个基于 Debian 的发行版，你可以从这里[下载][3]。请注意，此版本仅供非商业用途免费使用。
|
||||
|
||||
@@ -23,7 +24,7 @@ Wolfram 将一个版本 Mathematica 捆绑到了 Raspbian 中。在我们关于
|
||||
|
||||
要深入了解 Mathematica，请查看 [Wolfram 语言文档][5]。如果你只是想解决一些基本的微积分问题，请[查看它的函数][6]部分。如果你想[绘制一些 2D 和 3D 图形][7]，请阅读链接的教程。
|
||||
|
||||
或者，如果你想在做数学运算时坚持使用开源工具，请查看命令行工具 **expr**、**factor** 和 **bc**。（记住使用 [**man** 命令][8] 阅读使用帮助）如果想画图，[Gnuplot][9] 是个不错的选择。
|
||||
或者，如果你想在做数学运算时坚持使用开源工具，请查看命令行工具 `expr`、`factor` 和 `bc`。（记住使用 [man 命令][8] 阅读使用帮助）如果想画图，[Gnuplot][9] 是个不错的选择。
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
@@ -32,7 +33,7 @@ via: https://opensource.com/article/19/3/do-math-raspberry-pi
|
||||
作者：[Anderson Silva][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[geekpi](https://github.com/geekpi)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
校对：[wxy](https://github.com/wxy)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
@@ -46,4 +47,4 @@ via: https://opensource.com/article/19/3/do-math-raspberry-pi
|
||||
[6]: https://reference.wolfram.com/language/guide/Calculus.html
|
||||
[7]: https://reference.wolfram.com/language/howto/PlotAGraph.html
|
||||
[8]: https://opensource.com/article/19/3/learn-linux-raspberry-pi
|
||||
[9]: http://gnuplot.info/
|
||||
[9]: http://gnuplot.info/
|
||||
@@ -0,0 +1,53 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: (geekpi)
|
||||
[#]: reviewer: (wxy)
|
||||
[#]: publisher: (wxy)
|
||||
[#]: url: (https://linux.cn/article-10731-1.html)
|
||||
[#]: subject: (How to contribute to the Raspberry Pi community)
|
||||
[#]: via: (https://opensource.com/article/19/3/contribute-raspberry-pi-community)
|
||||
[#]: author: (Anderson Silva (Red Hat) https://opensource.com/users/ansilva/users/kepler22b/users/ansilva)
|
||||
|
||||
树莓派使用入门：如何为树莓派社区做出贡献
|
||||
======
|
||||
|
||||
> 在我们的入门系列的第 13 篇文章中，发现参与树莓派社区的方法。
|
||||
|
||||
![][1]
|
||||
|
||||
这个系列已经逐渐接近尾声，我已经写了很多它的乐趣，我大多希望它能帮助人们使用树莓派进行教育或娱乐。也许这些文章能说服你买你的第一个树莓派，或者让你重新发现抽屉里的吃灰设备。如果这里有真的，那么我认为这个系列就是成功的。
|
||||
|
||||
如果你想买一台，并宣传这块绿色的小板子有多么多功能，这里有几个方法帮你与树莓派社区建立连接：
|
||||
|
||||
* 帮助改进[官方文档][2]
|
||||
* 贡献代码给依赖的[项目][3]
|
||||
* 用 Raspbian 报告 [bug][4]
|
||||
* 报告不同 ARM 架构分发版的的 bug
|
||||
* 看一眼英国国内的树莓派基金会的[代码俱乐部][5]或英国境外的[国际代码俱乐部][6]，帮助孩子学习编码
|
||||
* 帮助[翻译][7]
|
||||
* 在 [Raspberry Jam][8] 当志愿者
|
||||
|
||||
这些只是你可以为树莓派社区做贡献的几种方式。最后但同样重要的是，你可以加入我并[投稿文章][9]到你最喜欢的开源网站 [Opensource.com][10]。 :-)
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/19/3/contribute-raspberry-pi-community
|
||||
|
||||
作者：[Anderson Silva (Red Hat)][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[geekpi](https://github.com/geekpi)
|
||||
校对：[wxy](https://github.com/wxy)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://opensource.com/users/ansilva/users/kepler22b/users/ansilva
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/raspberry_pi_community.jpg?itok=dcKwb5et
|
||||
[2]: https://www.raspberrypi.org/documentation/CONTRIBUTING.md
|
||||
[3]: https://www.raspberrypi.org/github/
|
||||
[4]: https://www.raspbian.org/RaspbianBugs
|
||||
[5]: https://www.codeclub.org.uk/
|
||||
[6]: https://www.codeclubworld.org/
|
||||
[7]: https://www.raspberrypi.org/translate/
|
||||
[8]: https://www.raspberrypi.org/jam/
|
||||
[9]: https://opensource.com/participate
|
||||
[10]: http://Opensource.com
|
||||
@@ -0,0 +1,75 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: (geekpi)
|
||||
[#]: reviewer: (wxy)
|
||||
[#]: publisher: (wxy)
|
||||
[#]: url: (https://linux.cn/article-10734-1.html)
|
||||
[#]: subject: (14 days of celebrating the Raspberry Pi)
|
||||
[#]: via: (https://opensource.com/article/19/3/happy-pi-day)
|
||||
[#]: author: (Anderson Silva (Red Hat) https://opensource.com/users/ansilva)
|
||||
|
||||
树莓派使用入门：庆祝树莓派的 14 天
|
||||
======
|
||||
|
||||
> 在我们关于树莓派入门系列的第 14 篇也是最后一篇文章中，回顾一下我们学到的所有东西。
|
||||
|
||||
![][1]
|
||||
|
||||
### 派节快乐！
|
||||
|
||||
每年的 3 月 14 日，我们这些极客都会庆祝派节。我们用这种方式缩写日期: `MMDD`，3 月 14 于是写成 03/14，它的数字上提醒我们 3.14，或者说 [π][2] 的前三位数字。许多美国人没有意识到的是，世界上几乎没有其他国家使用这种[日期格式][3]，因此派节几乎只适用于美国，尽管它在全球范围内得到了庆祝。
|
||||
|
||||
无论你身在何处，让我们一起庆祝树莓派，并通过回顾过去两周我们所涉及的主题来结束本系列：
|
||||
|
||||
* 第 1 天：[你应该选择哪种树莓派？][4]
|
||||
* 第 2 天：[如何购买树莓派][5]
|
||||
* 第 3 天：[如何启动一个新的树莓派][6]
|
||||
* 第 4 天：[用树莓派学习 Linux][7]
|
||||
* 第 5 天：[教孩子们用树莓派学编程的 5 种方法][8]
|
||||
* 第 6 天：[可以使用树莓派学习的 3 种流行编程语言][9]
|
||||
* 第 7 天：[如何更新树莓派][10]
|
||||
* 第 8 天：[如何使用树莓派来娱乐][11]
|
||||
* 第 9 天：[树莓派上的模拟器和原生 Linux 游戏][12]
|
||||
* 第 10 天：[进入物理世界 —— 如何使用树莓派的 GPIO 针脚][13]
|
||||
* 第 11 天：[通过树莓派和 kali Linux 学习计算机安全][14]
|
||||
* 第 12 天：[在树莓派上使用 Mathematica 进行高级数学运算][15]
|
||||
* 第 13 天：[如何为树莓派社区做出贡献][16]
|
||||
|
||||
![Pi Day illustration][18]
|
||||
|
||||
我将结束本系列，感谢所有关注的人，尤其是那些在过去 14 天里从中学到了东西的人！我还想鼓励大家不断扩展他们对树莓派以及围绕它构建的所有开源（和闭源）技术的了解。
|
||||
|
||||
我还鼓励你了解其他文化、哲学、宗教和世界观。让我们成为人类的是这种惊人的 (有时是有趣的) 能力，我们不仅要适应外部环境，而且要适应智力环境。
|
||||
|
||||
不管你做什么，保持学习！
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/19/3/happy-pi-day
|
||||
|
||||
作者：[Anderson Silva (Red Hat)][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[geekpi](https://github.com/geekpi)
|
||||
校对：[wxy](https://github.com/wxy)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://opensource.com/users/ansilva
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/raspberry-pi-juggle.png?itok=oTgGGSRA
|
||||
[2]: https://www.piday.org/million/
|
||||
[3]: https://en.wikipedia.org/wiki/Date_format_by_country
|
||||
[4]: https://linux.cn/article-10611-1.html
|
||||
[5]: https://linux.cn/article-10615-1.html
|
||||
[6]: https://linux.cn/article-10644-1.html
|
||||
[7]: https://linux.cn/article-10645-1.html
|
||||
[8]: https://linux.cn/article-10653-1.html
|
||||
[9]: https://linux.cn/article-10661-1.html
|
||||
[10]: https://linux.cn/article-10665-1.html
|
||||
[11]: https://linux.cn/article-10669-1.html
|
||||
[12]: https://linux.cn/article-10682-1.html
|
||||
[13]: https://linux.cn/article-10687-1.html
|
||||
[14]: https://linux.cn/article-10690-1.html
|
||||
[15]: https://linux.cn/article-10711-1.html
|
||||
[16]: https://linux.cn/article-10731-1.html
|
||||
[17]: /file/426561
|
||||
[18]: https://opensource.com/sites/default/files/uploads/raspberrypi_14_piday.jpg (Pi Day illustration)
|
||||
@@ -1,8 +1,8 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: (Moelf)
|
||||
[#]: reviewer: (acyanbird)
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: reviewer: (acyanbird, wxy)
|
||||
[#]: publisher: (wxy)
|
||||
[#]: url: (https://linux.cn/article-10714-1.html)
|
||||
[#]: subject: (A Look Back at the History of Firefox)
|
||||
[#]: via: (https://itsfoss.com/history-of-firefox)
|
||||
[#]: author: (John Paul https://itsfoss.com/author/john/)
|
||||
@@ -10,56 +10,57 @@
|
||||
回顾 Firefox 历史
|
||||
======
|
||||
|
||||
从很久之前开始，火狐浏览器就一直是开源社区的一根顶梁柱。这些年来它几乎是所有 Linux 发行版的默认浏览器，并且曾是阻挡微软彻底争霸浏览器界的最后一块磐石。这款浏览器的起源可以一直回溯到互联网创生的时代。本周（此文发布于 2019.3.14）是互联网成立 30 周年的纪念日，趁这个机会回顾一下我们熟悉并爱戴的火狐浏览器实在是再好不过了。
|
||||
从很久之前开始，火狐浏览器就一直是开源社区的一根顶梁柱。这些年来它几乎是所有 Linux 发行版的默认浏览器，并且曾是阻挡微软彻底争霸浏览器界的最后一块磐石。这款浏览器的起源可以一直回溯到互联网创生的时代。本周（LCTT 译注：此文发布于 2019.3.14）是互联网成立 30 周年的纪念日，趁这个机会回顾一下我们熟悉并爱戴的火狐浏览器实在是再好不过了。
|
||||
|
||||
### 发源
|
||||
|
||||
在90年代早期，一个叫 [Marc Andreessen][1] 的年轻人正在伊利诺伊大学攻读计算机科学学士学位。在那里，他开始为[国家超算应用中心][2]工作。就在这段时间内，[Tim Berners-Lee][3] 爵士发布了网络标准的早期版本 —— 现在这个网络广为人之。Marc 在那时候[了解][4]到了一款叫[ViolaWWW][5]的化石级浏览器。Marc 和 Eric Bina 看到了这种技术的潜力，他们开发了一个易于安装的基于 Unix 平台的浏览器，并取名 [NCSA Mosaic][6]。第一个 alpha 版本发布于 1993 年 6 月。到 9 月的时候，浏览器已经有 Windows 和 Macintosh 移植版本了。因为比当时其他任何浏览器软件都易于使用，Mosaic 很快变得相当流行。
|
||||
在上世纪 90 年代早期，一个叫 [Marc Andreessen][1] 的年轻人正在伊利诺伊大学攻读计算机科学学士学位。在那里，他开始为[国家超算应用中心（NCSA）][2]工作。就在这段时间内，<ruby>[蒂姆·伯纳斯·李][3]<rt>Tim Berners-Lee</rt></ruby> 爵士发布了今天已经为我们所熟知的 Web 的早期标准。Marc 在那时候[了解][4]到了一款叫 [ViolaWWW][5] 的化石级浏览器。Marc 和 Eric Bina 看到了这种技术的潜力，他们开发了一个易于安装的基于 Unix 平台的浏览器，并取名 [NCSA Mosaic][6]。第一个 alpha 版本发布于 1993 年 6 月。到 9 月的时候，浏览器已经有 Windows 和 Macintosh 移植版本了。因为比当时其他任何浏览器软件都易于使用，Mosaic 很快变得相当流行。
|
||||
|
||||
1994 年，Marc 毕业并移居到加州。一个叫 Jim Clark 的人结识了他，Clark 那时候通过卖电脑软硬件赚了点钱。Clark 也用过 Mosaic 浏览器并且在互联网上看到了发家的机会。Clark 创立了一家公司并且雇了 Marc 和 Eric 专做互联网软件。公司一开始叫 “Mosaic 通讯”，但是伊利诺伊大学不喜欢[ Mosaic 这个名字][7]。所以公司转而改名大家后来熟悉的 “网景通讯”。
|
||||
1994 年，Marc 毕业并移居到加州。一个叫 Jim Clark 的人结识了他，Clark 那时候通过卖电脑软硬件赚了点钱。Clark 也用过 Mosaic 浏览器并且看到了互联网的经济前景。Clark 创立了一家公司并且雇了 Marc 和 Eric 专做互联网软件。公司一开始叫 “Mosaic 通讯”，但是伊利诺伊大学并不喜欢他们用 [Mosaic 这个名字][7]。所以公司转而改名为 “<ruby>网景<rt>Netscape</rt></ruby>通讯”。
|
||||
|
||||
公司的第一个项目是给任天堂 64 开发在线对战网络，然而不怎么成功。他们第一个以公司名义发布的产品是一款叫做 Mosaic Netscape 0.9 的浏览器，很快这款浏览器被改名叫 Netscape Navigator。在内部，浏览器的开发代号就是 mozilla，意味着”Mosaic 杀手“。一位员工还创作了一幅[哥斯拉风格的][8]卡通画。他们当时想在竞争中彻底胜出。
|
||||
该公司的第一个项目是给任天堂 64 开发在线对战网络，然而不怎么成功。他们第一个以公司名义发布的产品是一款叫做 Mosaic Netscape 0.9 的浏览器，很快这款浏览器被改名叫 Netscape Navigator。在内部，浏览器的开发代号就是 mozilla，意即 “Mosaic 杀手”。一位员工还创作了一幅[哥斯拉风格的][8]卡通画。他们当时想在竞争中彻底胜出。
|
||||
|
||||
![Early Firefox Mascot][9]
|
||||
|
||||
![Early Firefox Mascot][9]早期 Mozilla 在 Netscape 的吉祥物
|
||||
*早期 Mozilla 在 Netscape 的吉祥物*
|
||||
|
||||
他们取得了辉煌的胜利。那时，Netscape 最大的优势是他们的浏览器在各种操作系统上体验极为一致。Netscape 把这个情况宣传为给所有人平等的互联网体验。
|
||||
他们取得了辉煌的胜利。那时，Netscape 最大的优势是他们的浏览器在各种操作系统上体验极为一致。Netscape 将其宣传为给所有人平等的互联网体验。
|
||||
|
||||
随着越来越多的人使用 Netscape Navigator，NCSA Mosaic 的市场份额逐步下降。到了 1995 年，Netscape 公开上市了。[第一天][10]，股价从开盘的 $28，直窜到 $78，收盘于 $58。Netscape 那时所向披靡。
|
||||
随着越来越多的人使用 Netscape Navigator，NCSA Mosaic 的市场份额逐步下降。到了 1995 年，Netscape 公开上市了。[上市首日][10]，股价从开盘的 $28，直窜到 $78，收盘于 $58。Netscape 那时所向披靡。
|
||||
|
||||
但好景不长。在 1994 年的夏天，微软发布了 Internet Explorer 1.0，这款浏览器基于 Spyglass Mosaic，而后者又直接基于 NCSA Mosaic。[浏览器战争][11] 就此展开。
|
||||
|
||||
在接下来的几年里，Netscape 和微软就浏览器霸主地位展开斗争。他们各自加入了很多新特性以取得优势。不幸的是，IE 有和 Windows 操作系统捆绑的巨大优势。更甚于此，微软也有更多的程序员和资本可以调动。在接近 1997 年的尾声，Netscape 公司开始遇到财务问题。
|
||||
|
||||
在接下来的几年里，Netscape 和微软就浏览器霸主地位展开斗争。他们各自加入了很多新特性以取得优势。不幸的是，IE 有和 Windows 操作系统捆绑的巨大优势。更甚于此，微软也有更多的程序员和资本可以调动。在 1997 年年底，Netscape 公司开始遇到财务问题。
|
||||
|
||||
### 迈向开源
|
||||
|
||||
![Mozilla Firefox][12]
|
||||
|
||||
1998 年 1 月，Netscape 开源了 Netscape Communicator 4.0 软件套装的代码。[旨在][13] “集合互联网上万千程序员的才智，把最好的功能加入 Netscape 的软件。这一策略能加速开发，并且让 Netscape 在未来能向个人和商业用户提供高质量的 Netscape Communicator 版本”。
|
||||
1998 年 1 月，Netscape 开源了 Netscape Communicator 4.0 软件套装的代码。[旨在][13] “集合互联网成千上万的程序员的才智，把最好的功能加入 Netscape 的软件。这一策略旨在加速开发，并且让 Netscape 在未来能向个人和商业用户免费提供高质量的 Netscape Communicator 版本”。
|
||||
|
||||
这个项目由新创立的 Mozilla Orgnization 管理。然而，Netscape Communicator 4.0 的代码由于大小和复杂程度，它很难被社区上的程序员们独自开发。雪上加霜的是，浏览器的一些组件由于第三方证书问题并不能被开源。到头来，他们决定用新兴的 [Gecko][14] 渲染引擎重新开发浏览器。
|
||||
这个项目由新创立的 Mozilla 机构管理。然而，Netscape Communicator 4.0 的代码由于大小和复杂程度而很难开发。雪上加霜的是，浏览器的一些组件由于第三方的许可证问题而不能被开源。到头来，他们决定用新兴的 [Gecko][14] 渲染引擎重新开发浏览器。
|
||||
|
||||
到了 1998 年的 11 月，Netscape 被美国在线（AOL）以[价值 42 亿美元的股权][15]收购。
|
||||
|
||||
从头来过是一项艰巨的任务。Mozilla Firefox（原名 Phoenix）直到 2002 年 6 月才面世，它同样可以运行在多种操作系统上：Linux，Mac OS，Windows 和 Solaris。
|
||||
从头来过是一项艰巨的任务。Mozilla Firefox（最初名为 Phoenix）直到 2002 年 6 月才面世，它同样可以运行在多种操作系统上：Linux、Mac OS、Windows 和 Solaris。
|
||||
|
||||
1999 年，AOL 宣布他们将停止浏览器开发。紧接着 Mozilla 基金会成立了，用于管理 Mozilla 的商标和项目相关的融资事宜。最早 Mozilla 基金会收到了一笔来自 AOL，IBM，Sun Microsystems 和红帽（Red Hat）总计 2 百万美金的捐赠。
|
||||
1999 年，AOL 宣布他们将停止浏览器开发。随后创建了 Mozilla 基金会，用于管理 Mozilla 的商标和项目相关的融资事宜。最早 Mozilla 基金会从 AOL、IBM、Sun Microsystems 和红帽（Red Hat）收到了总计 200 万美金的捐赠。
|
||||
|
||||
到了 2003 年 3 月，因为套件越来越臃肿，Mozilla [宣布][16] 计划把套件分割成单独的应用。这个单独的浏览器一开始起名 Phoenix。但是由于和 BIOS 制造企业凤凰科技的商标官司，浏览器改名 Firebird 火鸟 —— 结果和火鸟数据库的开发者又起了冲突。浏览器只能再次被重命名，才有了现在家喻户晓的 Firefox 火狐。
|
||||
到了 2003 年 3 月，因为套件越来越臃肿，Mozilla [宣布][16] 计划把该套件分割成单独的应用。这个单独的浏览器一开始起名 Phoenix。但是由于和 BIOS 制造企业凤凰科技的商标官司，浏览器改名 Firebird（火鸟） —— 结果和火鸟数据库的开发者又起了冲突。浏览器只能再次被重命名，才有了现在家喻户晓的 Firefox（火狐）。
|
||||
|
||||
那时，[Mozilla 说][17]，”我们在过去一年里学到了很多关于起名的技巧（不是因为我们愿意才学的）。我们现在很小心地研究了名字，确保不会再有什么夭蛾子了。我们同时展开了在美国专利局和商标办注册我们新品牌的流程”。
|
||||
那时，[Mozilla 说][17]，”我们在过去一年里学到了很多关于起名的技巧（不是因为我们愿意才学的）。我们现在很小心地研究了名字，确保不会再有什么夭蛾子了。我们已经开始向美国专利商标局注册我们新商标”。
|
||||
|
||||
![Mozilla Firefox 1.0][18]
|
||||
|
||||
![Mozilla Firefox 1.0][18]Firefox 1.0 : [图片致谢][19]
|
||||
*Firefox 1.0 : [图片致谢][19]*
|
||||
|
||||
第一个正式的 Firefox 版本是 [0.8][20]，发布于 2004 年 2 月 8 日。紧接着 11 月 9 日他们发布了 1.0 版本。接着 2.0 和 3.0 分别在 06 年 10 月 和 08 年 6 月问世。每个大版本更新都带来了很多新的特性和提升。从很多角度上讲，Firefox 都领先 IE 不少，无论是功能还是技术先进性，即便如此 IE 还是有更多用户。
|
||||
第一个正式的 Firefox 版本是 [0.8][20]，发布于 2004 年 2 月 8 日。紧接着 11 月 9 日他们发布了 1.0 版本。2.0 和 3.0 版本分别在 06 年 10 月 和 08 年 6 月问世。每个大版本更新都带来了很多新的特性和提升。从很多角度上讲，Firefox 都领先 IE 不少，无论是功能还是技术先进性，即便如此 IE 还是有更多用户。
|
||||
|
||||
一切都在 Google 发布 Chrome 浏览器的时候改变了。在 Chrome 发布（2008 年 9 月）的前几个月，Firefox 占有 30% 的[浏览器份额][21] 而 IE 有超过 60%。而在 [2019 年 1 月][22] 的 StatCounter's 报告里，Firefox 有不到 10% 的份额，而 Chrome 有超过 70%。
|
||||
一切都在 Google 发布 Chrome 浏览器的时候改变了。在 Chrome 发布（2008 年 9 月）的前几个月，Firefox 占有 30% 的[浏览器份额][21] 而 IE 有超过 60%。而在 StatCounter 的 [2019 年 1 月][22]报告里，Firefox 有不到 10% 的份额，而 Chrome 有超过 70%。
|
||||
|
||||
趣味知识点
|
||||
> 趣味知识点
|
||||
|
||||
和大家以为的不一样，火狐的 logo 其实没有狐狸。那其实是个 [小熊猫][23]。在中文里，“火狐狸”是小熊猫的一个昵称（译者：我真的从来没听说过）
|
||||
> 和大家以为的不一样，火狐的 logo 其实没有狐狸。那其实是个 <ruby>[小熊猫][23]<rt>Red Panda</rt></ruby>。在中文里，“火狐狸”是小熊猫的另一个名字。
|
||||
|
||||
### 展望未来
|
||||
|
||||
@@ -67,12 +68,11 @@
|
||||
|
||||
这也许看起来和 Netscape 当年的辉煌形成鲜明的对比。但让我们不要忘记 Firefox 已经有的许多成就。一群来自世界各地的程序员，就这么开发出了这个星球上第二大份额的浏览器。他们在微软垄断如日中天的时候还占据这 30% 的份额，他们可以再次做到这一点。无论如何，他们都有我们。开源社区坚定地站在他们身后。
|
||||
|
||||
抗争垄断是众多我使用 Firefox [的原因之一][26]。Mozilla 在改头换面的 [Firefox Quantum][27] 上赢回了一些份额，我相信他们还能一路向上攀爬。
|
||||
抗争垄断是我使用 Firefox [的众多原因之一][26]。随着 Mozilla 在改头换面的 [Firefox Quantum][27] 上赢回了一些份额，我相信它将一路向上攀爬。
|
||||
|
||||
你还想了解 Linux 和开源历史上的什么其他事件？欢迎在评论区告诉我们。
|
||||
|
||||
如果你觉得这篇文章不错，请大方在社交媒体上分享！比如 Hacker News 或者 [Reddit][28]。（译者：可惜 Reddit 已经是不存在的网站了）
|
||||
|
||||
如果你觉得这篇文章不错，请在社交媒体上分享！比如 Hacker News 或者 [Reddit][28]。
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
@@ -80,8 +80,8 @@ via: https://itsfoss.com/history-of-firefox
|
||||
|
||||
作者：[John Paul][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
译者：[Moelf](https://github.com/Moelf)
|
||||
校对：[acyanbird](https://github.com/acyanbird), [wxy](https://github.com/wxy)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
@@ -92,7 +92,7 @@ via: https://itsfoss.com/history-of-firefox
|
||||
[3]: https://en.wikipedia.org/wiki/Tim_Berners-Lee
|
||||
[4]: https://www.w3.org/DesignIssues/TimBook-old/History.html
|
||||
[5]: http://viola.org/
|
||||
[6]: https://en.wikipedia.org/wiki/Mosaic_(web_browser
|
||||
[6]: https://en.wikipedia.org/wiki/Mosaic_(web_browser)
|
||||
[7]: http://www.computinghistory.org.uk/det/1789/Marc-Andreessen/
|
||||
[8]: http://www.davetitus.com/mozilla/
|
||||
[9]: https://i1.wp.com/itsfoss.com/wp-content/uploads/2019/03/Mozilla_boxing.jpg?ssl=1
|
||||
@@ -110,7 +110,7 @@ via: https://itsfoss.com/history-of-firefox
|
||||
[21]: https://en.wikipedia.org/wiki/Usage_share_of_web_browsers
|
||||
[22]: http://gs.statcounter.com/browser-market-share/desktop/worldwide/#monthly-201901-201901-bar
|
||||
[23]: https://en.wikipedia.org/wiki/Red_panda
|
||||
[24]: https://en.wikipedia.org/wiki/Flock_(web_browser
|
||||
[24]: https://en.wikipedia.org/wiki/Flock_(web_browser)
|
||||
[25]: https://www.windowscentral.com/microsoft-building-chromium-powered-web-browser-windows-10
|
||||
[26]: https://itsfoss.com/why-firefox/
|
||||
[27]: https://itsfoss.com/firefox-quantum-ubuntu/
|
||||
@@ -1,24 +1,24 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: (geekpi)
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: reviewer: (wxy)
|
||||
[#]: publisher: (wxy)
|
||||
[#]: url: (https://linux.cn/article-10732-1.html)
|
||||
[#]: subject: (Sweet Home 3D: An open source tool to help you decide on your dream home)
|
||||
[#]: via: (https://opensource.com/article/19/3/tool-find-home)
|
||||
[#]: author: (Jeff Macharyas (Community Moderator) )
|
||||
|
||||
Sweet Home 3D：一个帮助你决定梦想家庭的开源工具
|
||||
Sweet Home 3D：一个帮助你寻找梦想家庭的开源工具
|
||||
======
|
||||
|
||||
室内设计应用可以轻松渲染你喜欢的房子，不管是真实的或是想象的。
|
||||
> 室内设计应用可以轻松渲染你喜欢的房子，不管是真实的或是想象的。
|
||||
|
||||
![Houses in a row][1]
|
||||
|
||||
我最近接受了一份在弗吉尼亚州的新工作。由于我妻子一直在纽约工作，看着我们在纽约的房子直至出售，我有责任出去为我们和我们的猫找一所新房子。在我们搬进去之前她不会看到的房子！
|
||||
我最近接受了一份在弗吉尼亚州的新工作。由于我妻子一直在纽约工作，看着我们在纽约的房子直至出售，我有责任出去为我们和我们的猫找一所新房子。在我们搬进去之前她看不到新房子。
|
||||
|
||||
我和一个房地产经纪人签约，并看了几间房子，拍了许多照片，写下了潦草的笔记。晚上，我会将照片上传到 Google Drive 文件夹中，我和我老婆会通过手机同时查看这些照片，同时我还想记住房间是在右边还是左边，是否有风扇等。
|
||||
我和一个房地产经纪人签约，并看了几间房子，拍了许多照片，写下了潦草的笔记。晚上，我会将照片上传到 Google Drive 文件夹中，我和我老婆会通过手机同时查看这些照片，同时我还要记住房间是在右边还是左边，是否有风扇等。
|
||||
|
||||
由于这是一个相当繁琐且不太准确的方式来展示我的发现，我因此去寻找一个开源解决方案，以更好地展示我们未来的梦想之家将会是什么样的，而不会取决于我的模糊记忆和模糊的照片。
|
||||
由于这是一个相当繁琐且不太准确的展示我的发现的方式，我因此去寻找一个开源解决方案，以更好地展示我们未来的梦想之家将会是什么样的，而不会取决于我的模糊记忆和模糊的照片。
|
||||
|
||||
[Sweet Home 3D][2] 完全满足了我的要求。Sweet Home 3D 可在 Sourceforge 上获取，并在 GNU 通用公共许可证下发布。它的[网站][3]信息非常丰富，我能够立即启动并运行。Sweet Home 3D 由总部位于巴黎的 eTeks 的 Emmanuel Puybaret 开发。
|
||||
|
||||
@@ -32,19 +32,19 @@ Sweet Home 3D：一个帮助你决定梦想家庭的开源工具
|
||||
|
||||
现在我画完了“内墙”，我从网站下载了各种“家具”，其中包括实际的家具以及门、窗、架子等。每个项目都以 ZIP 文件的形式下载，因此我创建了一个包含所有未压缩文件的文件夹。我可以自定义每件家具和重复的物品比如门，可以方便地复制粘贴到指定的地方。
|
||||
|
||||
在我将所有墙壁和门窗都布置完后，我就使用应用的 3D 视图浏览房屋。根据照片和记忆，我对所有物体进行了调整直到接近房屋的样子。我可以花更多时间添加纹理，附属家具和物品，但这已经达到了我需要的程度。
|
||||
在我将所有墙壁和门窗都布置完后，我就使用这个应用的 3D 视图浏览房屋。根据照片和记忆，我对所有物体进行了调整，直到接近房屋的样子。我可以花更多时间添加纹理，附属家具和物品，但这已经达到了我需要的程度。
|
||||
|
||||
![Sweet Home 3D floorplan][7]
|
||||
|
||||
完成之后，我将计划导出为 OBJ 文件，它可在各种程序中打开，例如 [Blender][8] 和 Mac 上的 Preview，方便旋转房屋并从各个角度查看。视频功能最有用，我可以创建一个起点，然后在房子中绘制一条路径，并记录“旅程”。我将视频导出为 MOV 文件，并使用 QuickTime 在 Mac 上打开和查看。
|
||||
完成之后，我将该项目导出为 OBJ 文件，它可在各种程序中打开，例如 [Blender][8] 和 Mac 上的“预览”中，方便旋转房屋并从各个角度查看。视频功能最有用，我可以创建一个起点，然后在房子中绘制一条路径，并记录“旅程”。我将视频导出为 MOV 文件，并使用 QuickTime 在 Mac 上打开和查看。
|
||||
|
||||
我的妻子能够（几乎）所有我看到的，我们甚至可以开始在搬家前布置家具。现在，我所要做的就是装上卡车搬到新家。
|
||||
我的妻子能够（几乎）能看到所有我看到的，我们甚至可以开始在搬家前布置家具。现在，我所要做的就是把行李装上卡车搬到新家。
|
||||
|
||||
Sweet Home 3D 在我的新工作中也是有用的。我正在寻找一种方法来改善学院建筑的地图，并计划在 [Inkscape][9] 或 Illustrator 或其他软件中重新绘制它。但是，由于我有平面地图，我可以使用 Sweet Home 3D 创建平面图的 3D 版本并将其上传到我们的网站以便更方便地找到地方。
|
||||
|
||||
### 开源犯罪现场？
|
||||
|
||||
一件有趣的事：根据 [Sweet Home 3D 的博客][10]，“法国法医办公室（科学警察）最近选择 Sweet Home 3D 作为设计计划表示路线和犯罪现场的工具。这是法国政府建议优先考虑免费开源解决方案的具体应用。“
|
||||
一件有趣的事：根据 [Sweet Home 3D 的博客][10]，“法国法医办公室（科学警察）最近选择 Sweet Home 3D 作为设计规划表示路线和犯罪现场的工具。这是法国政府建议优先考虑自由开源解决方案的具体应用。“
|
||||
|
||||
这是公民和政府如何利用开源解决方案创建个人项目、解决犯罪和建立世界的又一点证据。
|
||||
|
||||
@@ -55,11 +55,11 @@ via: https://opensource.com/article/19/3/tool-find-home
|
||||
作者：[Jeff Macharyas (Community Moderator)][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[geekpi](https://github.com/geekpi)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
校对：[wxy](https://github.com/wxy)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:
|
||||
[a]: https://opensource.com/users/jeffmacharyas
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/house_home_colors_live_building.jpg?itok=HLpsIfIL (Houses in a row)
|
||||
[2]: https://sourceforge.net/projects/sweethome3d/
|
||||
296
published/20190317 How To Configure sudo Access In Linux.md
Normal file
296
published/20190317 How To Configure sudo Access In Linux.md
Normal file
@@ -0,0 +1,296 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: (liujing97)
|
||||
[#]: reviewer: (wxy)
|
||||
[#]: publisher: (wxy)
|
||||
[#]: url: (https://linux.cn/article-10746-1.html)
|
||||
[#]: subject: (How To Configure sudo Access In Linux?)
|
||||
[#]: via: (https://www.2daygeek.com/how-to-configure-sudo-access-in-linux/)
|
||||
[#]: author: (Magesh Maruthamuthu https://www.2daygeek.com/author/magesh/)
|
||||
|
||||
如何在 Linux 中配置 sudo 访问权限
|
||||
======
|
||||
|
||||
Linux 系统中 root 用户拥有 Linux 中全部控制权力。Linux 系统中 root 是拥有最高权力的用户，可以在系统中实施任意的行为。
|
||||
|
||||
如果其他用户想去实施一些行为，不能为所有人都提供 root 访问权限。因为如果他或她做了一些错误的操作，没有办法去纠正它。
|
||||
|
||||
为了解决这个问题，有什么方案吗？
|
||||
|
||||
我们可以把 sudo 权限发放给相应的用户来克服这种情况。
|
||||
|
||||
`sudo` 命令提供了一种机制，它可以在不用分享 root 用户的密码的前提下，为信任的用户提供系统的管理权限。
|
||||
|
||||
他们可以执行大部分的管理操作，但又不像 root 一样有全部的权限。
|
||||
|
||||
### 什么是 sudo？
|
||||
|
||||
`sudo` 是一个程序，普通用户可以使用它以超级用户或其他用户的身份执行命令，是由安全策略指定的。
|
||||
|
||||
sudo 用户的访问权限是由 `/etc/sudoers` 文件控制的。
|
||||
|
||||
### sudo 用户有什么优点？
|
||||
|
||||
在 Linux 系统中，如果你不熟悉一个命令，`sudo` 是运行它的一个安全方式。
|
||||
|
||||
* Linux 系统在 `/var/log/secure` 和 `/var/log/auth.log` 文件中保留日志，并且你可以验证 sudo 用户实施了哪些行为操作。
|
||||
* 每一次它都为当前的操作提示输入密码。所以，你将会有时间去验证这个操作是不是你想要执行的。如果你发觉它是不正确的行为，你可以安全地退出而且没有执行此操作。
|
||||
|
||||
基于 RHEL 的系统（如 Redhat (RHEL)、 CentOS 和 Oracle Enterprise Linux (OEL)）和基于 Debian 的系统（如 Debian、Ubuntu 和 LinuxMint）在这点是不一样的。
|
||||
|
||||
我们将会教你如何在本文中提及的两种发行版中执行该操作。
|
||||
|
||||
这里有三种方法可以应用于两个发行版本。
|
||||
|
||||
* 增加用户到相应的组。基于 RHEL 的系统，我们需要添加用户到 `wheel` 组。基于 Debain 的系统，我们添加用户到 `sudo` 或 `admin` 组。
|
||||
* 手动添加用户到 `/etc/group` 文件中。
|
||||
* 用 `visudo` 命令添加用户到 `/etc/sudoers` 文件中。
|
||||
|
||||
### 如何在 RHEL/CentOS/OEL 系统中配置 sudo 访问权限？
|
||||
|
||||
在基于 RHEL 的系统中（如 Redhat (RHEL)、 CentOS 和 Oracle Enterprise Linux (OEL)），使用下面的三个方法就可以做到。
|
||||
|
||||
#### 方法 1：在 Linux 中如何使用 wheel 组为普通用户授予超级用户访问权限？
|
||||
|
||||
wheel 是基于 RHEL 的系统中的一个特殊组，它提供额外的权限，可以授权用户像超级用户一样执行受到限制的命令。
|
||||
|
||||
注意，应该在 `/etc/sudoers` 文件中激活 `wheel` 组来获得该访问权限。
|
||||
|
||||
```
|
||||
# grep -i wheel /etc/sudoers
|
||||
|
||||
## Allows people in group wheel to run all commands
|
||||
%wheel ALL=(ALL) ALL
|
||||
# %wheel ALL=(ALL) NOPASSWD: ALL
|
||||
```
|
||||
|
||||
假设我们已经创建了一个用户账号来执行这些操作。在此，我将会使用 `daygeek` 这个用户账号。
|
||||
|
||||
执行下面的命令，添加用户到 `wheel` 组。
|
||||
|
||||
```
|
||||
# usermod -aG wheel daygeek
|
||||
```
|
||||
|
||||
我们可以通过下面的命令来确定这一点。
|
||||
|
||||
```
|
||||
# getent group wheel
|
||||
wheel:x:10:daygeek
|
||||
```
|
||||
|
||||
我将要检测用户 `daygeek` 是否可以访问属于 root 用户的文件。
|
||||
|
||||
```
|
||||
$ tail -5 /var/log/secure
|
||||
tail: cannot open /var/log/secure for reading: Permission denied
|
||||
```
|
||||
|
||||
当我试图以普通用户身份访问 `/var/log/secure` 文件时出现错误。 我将使用 `sudo` 访问同一个文件，让我们看看这个魔术。
|
||||
|
||||
```
|
||||
$ sudo tail -5 /var/log/secure
|
||||
[sudo] password for daygeek:
|
||||
Mar 17 07:01:56 CentOS7 sudo: daygeek : TTY=pts/0 ; PWD=/home/daygeek ; USER=root ; COMMAND=/bin/tail -5 /var/log/secure
|
||||
Mar 17 07:01:56 CentOS7 sudo: pam_unix(sudo:session): session opened for user root by daygeek(uid=0)
|
||||
Mar 17 07:01:56 CentOS7 sudo: pam_unix(sudo:session): session closed for user root
|
||||
Mar 17 07:05:10 CentOS7 sudo: daygeek : TTY=pts/0 ; PWD=/home/daygeek ; USER=root ; COMMAND=/bin/tail -5 /var/log/secure
|
||||
Mar 17 07:05:10 CentOS7 sudo: pam_unix(sudo:session): session opened for user root by daygeek(uid=0)
|
||||
```
|
||||
|
||||
#### 方法 2：在 RHEL/CentOS/OEL 中如何使用 /etc/group 文件为普通用户授予超级用户访问权限？
|
||||
|
||||
我们可以通过编辑 `/etc/group` 文件来手动地添加用户到 `wheel` 组。
|
||||
|
||||
只需打开该文件，并在恰当的组后追加相应的用户就可完成这一点。
|
||||
|
||||
```
|
||||
$ grep -i wheel /etc/group
|
||||
wheel:x:10:daygeek,user1
|
||||
```
|
||||
|
||||
在该例中，我将使用 `user1` 这个用户账号。
|
||||
|
||||
我将要通过在系统中重启 Apache httpd 服务来检查用户 `user1` 是不是拥有 sudo 访问权限。让我们看看这个魔术。
|
||||
|
||||
```
|
||||
$ sudo systemctl restart httpd
|
||||
[sudo] password for user1:
|
||||
|
||||
$ sudo grep -i user1 /var/log/secure
|
||||
[sudo] password for user1:
|
||||
Mar 17 07:09:47 CentOS7 sudo: user1 : TTY=pts/0 ; PWD=/home/user1 ; USER=root ; COMMAND=/bin/systemctl restart httpd
|
||||
Mar 17 07:10:40 CentOS7 sudo: user1 : TTY=pts/0 ; PWD=/home/user1 ; USER=root ; COMMAND=/bin/systemctl restart httpd
|
||||
Mar 17 07:12:35 CentOS7 sudo: user1 : TTY=pts/0 ; PWD=/home/user1 ; USER=root ; COMMAND=/bin/grep -i httpd /var/log/secure
|
||||
```
|
||||
|
||||
#### 方法 3：在 Linux 中如何使用 /etc/sudoers 文件为普通用户授予超级用户访问权限？
|
||||
|
||||
sudo 用户的访问权限是被 `/etc/sudoers` 文件控制的。因此，只需将用户添加到 `sudoers` 文件中 的 `wheel` 组下即可。
|
||||
|
||||
只需通过 `visudo` 命令将期望的用户追加到 `/etc/sudoers` 文件中。
|
||||
|
||||
```
|
||||
# grep -i user2 /etc/sudoers
|
||||
user2 ALL=(ALL) ALL
|
||||
```
|
||||
|
||||
在该例中，我将使用 `user2` 这个用户账号。
|
||||
|
||||
我将要通过在系统中重启 MariaDB 服务来检查用户 `user2` 是不是拥有 sudo 访问权限。让我们看看这个魔术。
|
||||
|
||||
```
|
||||
$ sudo systemctl restart mariadb
|
||||
[sudo] password for user2:
|
||||
|
||||
$ sudo grep -i mariadb /var/log/secure
|
||||
[sudo] password for user2:
|
||||
Mar 17 07:23:10 CentOS7 sudo: user2 : TTY=pts/0 ; PWD=/home/user2 ; USER=root ; COMMAND=/bin/systemctl restart mariadb
|
||||
Mar 17 07:26:52 CentOS7 sudo: user2 : TTY=pts/0 ; PWD=/home/user2 ; USER=root ; COMMAND=/bin/grep -i mariadb /var/log/secure
|
||||
```
|
||||
|
||||
### 在 Debian/Ubuntu 系统中如何配置 sudo 访问权限？
|
||||
|
||||
在基于 Debian 的系统中（如 Debian、Ubuntu 和 LinuxMint），使用下面的三个方法就可以做到。
|
||||
|
||||
#### 方法 1：在 Linux 中如何使用 sudo 或 admin 组为普通用户授予超级用户访问权限？
|
||||
|
||||
`sudo` 或 `admin` 是基于 Debian 的系统中的特殊组，它提供额外的权限，可以授权用户像超级用户一样执行受到限制的命令。
|
||||
|
||||
注意，应该在 `/etc/sudoers` 文件中激活 `sudo` 或 `admin` 组来获得该访问权限。
|
||||
|
||||
```
|
||||
# grep -i 'sudo\|admin' /etc/sudoers
|
||||
|
||||
# Members of the admin group may gain root privileges
|
||||
%admin ALL=(ALL) ALL
|
||||
|
||||
# Allow members of group sudo to execute any command
|
||||
%sudo ALL=(ALL:ALL) ALL
|
||||
```
|
||||
|
||||
假设我们已经创建了一个用户账号来执行这些操作。在此，我将会使用 `2gadmin` 这个用户账号。
|
||||
|
||||
执行下面的命令，添加用户到 `sudo` 组。
|
||||
|
||||
```
|
||||
# usermod -aG sudo 2gadmin
|
||||
```
|
||||
|
||||
我们可以通过下面的命令来确定这一点。
|
||||
|
||||
```
|
||||
# getent group sudo
|
||||
sudo:x:27:2gadmin
|
||||
```
|
||||
|
||||
我将要检测用户 `2gadmin` 是否可以访问属于 root 用户的文件。
|
||||
|
||||
```
|
||||
$ less /var/log/auth.log
|
||||
/var/log/auth.log: Permission denied
|
||||
```
|
||||
|
||||
当我试图以普通用户身份访问 `/var/log/auth.log` 文件时出现错误。 我将要使用 `sudo` 访问同一个文件，让我们看看这个魔术。
|
||||
|
||||
```
|
||||
$ sudo tail -5 /var/log/auth.log
|
||||
[sudo] password for 2gadmin:
|
||||
Mar 17 20:39:47 Ubuntu18 sudo: 2gadmin : TTY=pts/0 ; PWD=/home/2gadmin ; USER=root ; COMMAND=/bin/bash
|
||||
Mar 17 20:39:47 Ubuntu18 sudo: pam_unix(sudo:session): session opened for user root by 2gadmin(uid=0)
|
||||
Mar 17 20:40:23 Ubuntu18 sudo: pam_unix(sudo:session): session closed for user root
|
||||
Mar 17 20:40:48 Ubuntu18 sudo: 2gadmin : TTY=pts/0 ; PWD=/home/2gadmin ; USER=root ; COMMAND=/usr/bin/tail -5 /var/log/auth.log
|
||||
Mar 17 20:40:48 Ubuntu18 sudo: pam_unix(sudo:session): session opened for user root by 2gadmin(uid=0)
|
||||
```
|
||||
|
||||
或者，我们可以通过添加用户到 `admin` 组来执行相同的操作。
|
||||
|
||||
运行下面的命令，添加用户到 `admin` 组。
|
||||
|
||||
```
|
||||
# usermod -aG admin user1
|
||||
```
|
||||
|
||||
我们可以通过下面的命令来确定这一点。
|
||||
|
||||
```
|
||||
# getent group admin
|
||||
admin:x:1011:user1
|
||||
```
|
||||
|
||||
让我们看看输出信息。
|
||||
|
||||
```
|
||||
$ sudo tail -2 /var/log/auth.log
|
||||
[sudo] password for user1:
|
||||
Mar 17 20:53:36 Ubuntu18 sudo: user1 : TTY=pts/0 ; PWD=/home/user1 ; USER=root ; COMMAND=/usr/bin/tail -2 /var/log/auth.log
|
||||
Mar 17 20:53:36 Ubuntu18 sudo: pam_unix(sudo:session): session opened for user root by user1(uid=0)
|
||||
```
|
||||
|
||||
#### 方法 2：在 Debian/Ubuntu 中如何使用 /etc/group 文件为普通用户授予超级用户访问权限？
|
||||
|
||||
我们可以通过编辑 `/etc/group` 文件来手动地添加用户到 `sudo` 组或 `admin` 组。
|
||||
|
||||
只需打开该文件，并在恰当的组后追加相应的用户就可完成这一点。
|
||||
|
||||
```
|
||||
$ grep -i sudo /etc/group
|
||||
sudo:x:27:2gadmin,user2
|
||||
```
|
||||
|
||||
在该例中，我将使用 `user2` 这个用户账号。
|
||||
|
||||
我将要通过在系统中重启 Apache httpd 服务来检查用户 `user2` 是不是拥有 `sudo` 访问权限。让我们看看这个魔术。
|
||||
|
||||
```
|
||||
$ sudo systemctl restart apache2
|
||||
[sudo] password for user2:
|
||||
|
||||
$ sudo tail -f /var/log/auth.log
|
||||
[sudo] password for user2:
|
||||
Mar 17 21:01:04 Ubuntu18 systemd-logind[559]: New session 22 of user user2.
|
||||
Mar 17 21:01:04 Ubuntu18 systemd: pam_unix(systemd-user:session): session opened for user user2 by (uid=0)
|
||||
Mar 17 21:01:33 Ubuntu18 sudo: user2 : TTY=pts/0 ; PWD=/home/user2 ; USER=root ; COMMAND=/bin/systemctl restart apache2
|
||||
```
|
||||
|
||||
#### 方法 3：在 Linux 中如何使用 /etc/sudoers 文件为普通用户授予超级用户访问权限？
|
||||
|
||||
sudo 用户的访问权限是被 `/etc/sudoers` 文件控制的。因此，只需将用户添加到 `sudoers` 文件中的 `sudo` 或 `admin` 组下即可。
|
||||
|
||||
只需通过 `visudo` 命令将期望的用户追加到 `/etc/sudoers` 文件中。
|
||||
|
||||
```
|
||||
# grep -i user3 /etc/sudoers
|
||||
user3 ALL=(ALL:ALL) ALL
|
||||
```
|
||||
|
||||
在该例中，我将使用 `user3` 这个用户账号。
|
||||
|
||||
我将要通过在系统中重启 MariaDB 服务来检查用户 `user3` 是不是拥有 `sudo` 访问权限。让我们看看这个魔术。
|
||||
|
||||
```
|
||||
$ sudo systemctl restart mariadb
|
||||
[sudo] password for user3:
|
||||
|
||||
$ sudo tail -f /var/log/auth.log
|
||||
[sudo] password for user3:
|
||||
Mar 17 21:12:32 Ubuntu18 systemd-logind[559]: New session 24 of user user3.
|
||||
Mar 17 21:12:49 Ubuntu18 sudo: user3 : TTY=pts/0 ; PWD=/home/user3 ; USER=root ; COMMAND=/bin/systemctl restart mariadb
|
||||
Mar 17 21:12:49 Ubuntu18 sudo: pam_unix(sudo:session): session opened for user root by user3(uid=0)
|
||||
Mar 17 21:12:53 Ubuntu18 sudo: pam_unix(sudo:session): session closed for user root
|
||||
Mar 17 21:13:08 Ubuntu18 sudo: user3 : TTY=pts/0 ; PWD=/home/user3 ; USER=root ; COMMAND=/usr/bin/tail -f /var/log/auth.log
|
||||
Mar 17 21:13:08 Ubuntu18 sudo: pam_unix(sudo:session): session opened for user root by user3(uid=0)
|
||||
```
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.2daygeek.com/how-to-configure-sudo-access-in-linux/
|
||||
|
||||
作者：[Magesh Maruthamuthu][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[liujing97](https://github.com/liujing97)
|
||||
校对：[wxy](https://github.com/wxy)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://www.2daygeek.com/author/magesh/
|
||||
[b]: https://github.com/lujun9972
|
||||
144
published/20190326 Using Square Brackets in Bash- Part 1.md
Normal file
144
published/20190326 Using Square Brackets in Bash- Part 1.md
Normal file
@@ -0,0 +1,144 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: (HankChow)
|
||||
[#]: reviewer: (wxy)
|
||||
[#]: publisher: (wxy)
|
||||
[#]: url: (https://linux.cn/article-10717-1.html)
|
||||
[#]: subject: (Using Square Brackets in Bash: Part 1)
|
||||
[#]: via: (https://www.linux.com/blog/2019/3/using-square-brackets-bash-part-1)
|
||||
[#]: author: (Paul Brown https://www.linux.com/users/bro66)
|
||||
|
||||
在 Bash 中使用[方括号] （一）
|
||||
======
|
||||
|
||||
![square brackets][1]
|
||||
|
||||
> 这篇文章将要介绍方括号及其在命令行中的不同用法。
|
||||
|
||||
看完[花括号在命令行中的用法][3]之后，现在我们继续来看方括号（`[]`）在上下文中是如何发挥作用的。
|
||||
|
||||
### 通配
|
||||
|
||||
方括号最简单的用法就是通配。你可能在知道“<ruby><rt>Globbing</rt></ruby>”这个概念之前就已经通过通配来匹配内容了，列出具有相同特征的多个文件就是一个很常见的场景，例如列出所有 JPEG 文件：
|
||||
|
||||
```
|
||||
ls *.jpg
|
||||
```
|
||||
|
||||
使用<ruby>通配符<rt>wildcard</rt></ruby>来得到符合某个模式的所有内容，这个过程就叫通配。
|
||||
|
||||
在上面的例子当中，星号（`*`）就代表“0 个或多个字符”。除此以外，还有代表“有且仅有一个字符”的问号（`?`）。因此
|
||||
|
||||
```
|
||||
ls d*k*
|
||||
```
|
||||
|
||||
可以列出 `darkly` 和 `ducky`，而且 `dark` 和 `duck` 也是可以被列出的，因为 `*` 可以匹配 0 个字符。而
|
||||
|
||||
```
|
||||
ls d*k?
|
||||
```
|
||||
|
||||
则只能列出 `ducky`，不会列出 `darkly`、`dark` 和 `duck`。
|
||||
|
||||
方括号也可以用于通配。为了便于演示，可以创建一个用于测试的目录，并在这个目录下创建文件：
|
||||
|
||||
```
|
||||
touch file0{0..9}{0..9}
|
||||
```
|
||||
|
||||
（如果你还不清楚上面这个命令的原理，可以看一下[另一篇介绍花括号的文章][3]）
|
||||
|
||||
执行上面这个命令之后，就会创建 `file000`、`file001`、……、`file099` 这 100 个文件。
|
||||
|
||||
如果要列出这些文件当中第二位数字是 7 或 8 的文件，可以执行：
|
||||
|
||||
```
|
||||
ls file0[78]?
|
||||
```
|
||||
|
||||
如果要列出 `file022`、`file027`、`file028`、`file052`、`file057`、`file058`、`file092`、`file097`、`file098`，可以执行：
|
||||
|
||||
```
|
||||
ls file0[259][278]
|
||||
```
|
||||
|
||||
当然，不仅仅是 `ls`，很多其它的命令行工具都可以使用方括号来进行通配操作。但在删除文件、移动文件、复制文件的过程中使用通配，你需要有一点横向思维。
|
||||
|
||||
例如将 `file010` 到 `file029` 这 30 个文件复制成 `archive010` 到 `archive029` 这 30 个副本，不可以这样执行：
|
||||
|
||||
```
|
||||
cp file0[12]? archive0[12]?
|
||||
```
|
||||
|
||||
因为通配只能针对已有的文件，而 `archive` 开头的文件并不存在，不能进行通配。
|
||||
|
||||
而这条命令
|
||||
|
||||
```
|
||||
cp file0[12]? archive0[1..2][0..9]
|
||||
```
|
||||
|
||||
也同样不行，因为 `cp` 并不允许将多个文件复制到多个文件。在复制多个文件的情况下，只能将多个文件复制到一个指定的目录下：
|
||||
|
||||
```
|
||||
mkdir archive
|
||||
cp file0[12]? archive
|
||||
```
|
||||
|
||||
这条命令是可以正常运行的，但它只会把这 30 个文件以同样的名称复制到 `archive/` 目录下，而这并不是我们想要的效果。
|
||||
|
||||
如果你阅读过我[关于花括号的文章][3]，你大概会记得可以使用 `%` 来截掉字符串的末尾部分，而使用 `#` 则可以截掉字符串的开头部分。
|
||||
|
||||
例如：
|
||||
|
||||
```
|
||||
myvar="Hello World"
|
||||
echo Goodbye Cruel ${myvar#Hello}
|
||||
```
|
||||
|
||||
就会输出 `Goodbye Cruel World`，因为 `#Hello` 将 `myvar` 变量中开头的 `Hello` 去掉了。
|
||||
|
||||
在通配的过程中，也可以使用这一个技巧。
|
||||
|
||||
```
|
||||
for i in file0[12]?;\
|
||||
do\
|
||||
cp $i archive${i#file};\
|
||||
done
|
||||
```
|
||||
|
||||
上面的第一行命令告诉 Bash 需要对所有 `file01` 开头或者 `file02` 开头，且后面只跟一个任意字符的文件进行操作，第二行的 `do` 和第四行的 `done` 代表需要对这些文件都执行这一块中的命令。
|
||||
|
||||
第三行就是实际的复制操作了，这里使用了两次 `$i` 变量：第一次在 `cp` 命令中直接作为源文件的文件名使用，第二次则是截掉文件名开头的 `file` 部分，然后在开头补上一个 `archive`，也就是这样：
|
||||
|
||||
```
|
||||
"archive" + "file019" - "file" = "archive019"
|
||||
```
|
||||
|
||||
最终整个 `cp` 命令展开为：
|
||||
|
||||
```
|
||||
cp file019 archive019
|
||||
```
|
||||
|
||||
最后，顺带说明一下反斜杠 `\` 的作用是将一条长命令拆分成多行，这样可以方便阅读。
|
||||
|
||||
在下一节，我们会了解方括号的更多用法，敬请关注。
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.linux.com/blog/2019/3/using-square-brackets-bash-part-1
|
||||
|
||||
作者：[Paul Brown][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[HankChow](https://github.com/HankChow)
|
||||
校对：[wxy](https://github.com/wxy)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://www.linux.com/users/bro66
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://www.linux.com/sites/lcom/files/styles/rendered_file/public/square-gabriele-diwald-475007-unsplash.jpg?itok=cKmysLfd "square brackets"
|
||||
[2]: https://www.linux.com/LICENSES/CATEGORY/CREATIVE-COMMONS-ZERO
|
||||
[3]: https://linux.cn/article-10624-1.html
|
||||
|
||||
@@ -1,18 +1,18 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: (geekpi)
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: reviewer: (wxy)
|
||||
[#]: publisher: (wxy)
|
||||
[#]: url: (https://linux.cn/article-10715-1.html)
|
||||
[#]: subject: (Setting kernel command line arguments with Fedora 30)
|
||||
[#]: via: (https://fedoramagazine.org/setting-kernel-command-line-arguments-with-fedora-30/)
|
||||
[#]: author: (Laura Abbott https://fedoramagazine.org/makes-fedora-kernel/)
|
||||
|
||||
在 Fedora 30 中设置内核命令行参数
|
||||
如何在 Fedora 30 中设置内核命令行参数
|
||||
======
|
||||
|
||||
![][1]
|
||||
|
||||
在调试或试验内核时，向内核命令行添加选项是一项常见任务。即将发布的 Fedora 30 版本改为使用 Bootloader 规范（[BLS] [2]）。根据你修改内核命令行选项的方式，你的工作流可能会更改。继续阅读获取更多信息。
|
||||
在调试或试验内核时，向内核命令行添加选项是一项常见任务。即将发布的 Fedora 30 版本改为使用 Bootloader 规范（[BLS][2]）。根据你修改内核命令行选项的方式，你的工作流可能会更改。继续阅读获取更多信息。
|
||||
|
||||
要确定你的系统是使用 BLS 还是旧的规范，请查看文件：
|
||||
|
||||
@@ -28,24 +28,19 @@ GRUB_ENABLE_BLSCFG=true
|
||||
|
||||
看到这个，你运行的是 BLS，你可能需要更改设置内核命令行参数的方式。
|
||||
|
||||
如果你只想修改单个内核条目（例如，暂时解决显示问题），可以使用 grubby 命令：
|
||||
如果你只想修改单个内核条目（例如，暂时解决显示问题），可以使用 `grubby` 命令：
|
||||
|
||||
```
|
||||
$ grubby --update-kernel /boot/vmlinuz-5.0.1-300.fc30.x86_64 --args="amdgpu.dc=0"
|
||||
```
|
||||
|
||||
要删除内核参数，可以传递
|
||||
|
||||
```
|
||||
--remove-args
|
||||
```
|
||||
参数给 grubby
|
||||
要删除内核参数，可以传递 `--remove-args` 参数给 `grubby`：
|
||||
|
||||
```
|
||||
$ grubby --update-kernel /boot/vmlinuz-5.0.1-300.fc30.x86_64 --remove-args="amdgpu.dc=0"
|
||||
```
|
||||
|
||||
如果有应该添加到每个内核命令行的选项（例如，你希望禁用 rdrand 指令生成随机数），则可以运行 grubby 命令：
|
||||
如果有应该添加到每个内核命令行的选项（例如，你希望禁用 `rdrand` 指令生成随机数），则可以运行 `grubby` 命令：
|
||||
|
||||
```
|
||||
$ grubby --update-kernel=ALL --args="nordrand"
|
||||
@@ -53,16 +48,7 @@ $ grubby --update-kernel=ALL --args="nordrand"
|
||||
|
||||
这将更新所有内核条目的命令行，并保存作为将来条目的命令行选项。
|
||||
|
||||
如果你想要从所有内核中删除该选项，则可以再次使用
|
||||
|
||||
```
|
||||
--remove-args
|
||||
```
|
||||
还有
|
||||
|
||||
```
|
||||
--update-kernel=ALL
|
||||
```
|
||||
如果你想要从所有内核中删除该选项，则可以再次使用 `--remove-args` 和 `--update-kernel=ALL`：
|
||||
|
||||
```
|
||||
$ grubby --update-kernel=ALL --remove-args="nordrand"
|
||||
@@ -75,7 +61,7 @@ via: https://fedoramagazine.org/setting-kernel-command-line-arguments-with-fedor
|
||||
作者：[Laura Abbott][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[geekpi](https://github.com/geekpi)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
校对：[wxy](https://github.com/wxy)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
70
published/20190401 3 cool text-based email clients.md
Normal file
70
published/20190401 3 cool text-based email clients.md
Normal file
@@ -0,0 +1,70 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: (geekpi)
|
||||
[#]: reviewer: (wxy)
|
||||
[#]: publisher: (wxy)
|
||||
[#]: url: (https://linux.cn/article-10722-1.html)
|
||||
[#]: subject: (3 cool text-based email clients)
|
||||
[#]: via: (https://fedoramagazine.org/3-cool-text-based-email-clients/)
|
||||
[#]: author: (Clément Verna https://fedoramagazine.org/author/cverna/)
|
||||
|
||||
3 个很酷的基于文本的邮件客户端
|
||||
======
|
||||
|
||||
![][1]
|
||||
|
||||
编写和接收电子邮件是每个人日常工作的重要组成部分，选择电子邮件客户端通常是一个重要决定。Fedora 系统提供了大量的电子邮件客户端可供选择，其中包括基于文本的电子邮件应用。
|
||||
|
||||
### Mutt
|
||||
|
||||
Mutt 可能是最受欢迎的基于文本的电子邮件客户端之一。它有人们期望的所有常用功能。Mutt 支持颜色代码、邮件会话、POP3 和 IMAP。但它最好的功能之一是它具有高度可配置性。实际上，用户可以轻松地更改键绑定，并创建宏以使工具适应特定的工作流程。
|
||||
|
||||
要尝试 Mutt，请[使用 sudo][2] 和 `dnf` 安装它：
|
||||
|
||||
```
|
||||
$ sudo dnf install mutt
|
||||
```
|
||||
|
||||
为了帮助新手入门，Mutt 有一个非常全面的充满了宏示例和配置技巧的 [wiki][3]。
|
||||
|
||||
### Alpine
|
||||
|
||||
Alpine 也是最受欢迎的基于文本的电子邮件客户端。它比 Mutt 更适合初学者，你可以通过应用本身配置大部分功能而无需编辑配置文件。Alpine 的一个强大功能是能够对电子邮件进行评分。这对那些订阅含有大量邮件的邮件列表如 Fedora 的[开发列表][4]的用户来说尤其有趣。通过使用分数，Alpine 可以根据用户的兴趣对电子邮件进行排序，首先显示高分的电子邮件。
|
||||
|
||||
也可以使用 `dnf` 从 Fedora 的仓库安装 Alpine。
|
||||
|
||||
```
|
||||
$ sudo dnf install alpine
|
||||
```
|
||||
|
||||
使用 Alpine 时，你可以按 `Ctrl+G` 组合键轻松访问文档。
|
||||
|
||||
### nmh
|
||||
|
||||
nmh（new Mail Handling）遵循 UNIX 工具哲学。它提供了一组用于发送、接收、保存、检索和操作电子邮件的单一用途程序。这使你可以将 `nmh` 命令与其他程序交换，或利用 `nmh` 编写脚本来创建更多自定义工具。例如，你可以将 Mutt 与 `nmh` 一起使用。
|
||||
|
||||
使用 `dnf` 可以轻松安装 `nmh`。
|
||||
|
||||
```
|
||||
$ sudo dnf install nmh
|
||||
```
|
||||
|
||||
要了解有关 `nmh` 和邮件处理的更多信息，你可以阅读这本 GPL 许可的[书][5]。
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://fedoramagazine.org/3-cool-text-based-email-clients/
|
||||
|
||||
作者：[Clément Verna][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[geekpi](https://github.com/geekpi)
|
||||
校对：[wxy](https://github.com/wxy)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://fedoramagazine.org/author/cverna/
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://fedoramagazine.org/wp-content/uploads/2018/07/email-clients-816x345.png
|
||||
[2]: https://fedoramagazine.org/howto-use-sudo/
|
||||
[3]: https://gitlab.com/muttmua/mutt/wikis/home
|
||||
[4]: https://lists.fedoraproject.org/archives/list/devel@lists.fedoraproject.org/
|
||||
[5]: https://rand-mh.sourceforge.io/book/
|
||||
@@ -0,0 +1,74 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: (geekpi)
|
||||
[#]: reviewer: (wxy)
|
||||
[#]: publisher: (wxy)
|
||||
[#]: url: (https://linux.cn/article-10742-1.html)
|
||||
[#]: subject: (Parallel computation in Python with Dask)
|
||||
[#]: via: (https://opensource.com/article/19/4/parallel-computation-python-dask)
|
||||
[#]: author: (Moshe Zadka (Community Moderator) https://opensource.com/users/moshez)
|
||||
|
||||
使用 Dask 在 Python 中进行并行计算
|
||||
======
|
||||
|
||||
> Dask 库可以将 Python 计算扩展到多个核心甚至是多台机器。
|
||||
|
||||
![Pair programming][1]
|
||||
|
||||
关于 Python 性能的一个常见抱怨是[全局解释器锁][2]（GIL）。由于 GIL，同一时刻只能有一个线程执行 Python 字节码。因此，即使在现代的多核机器上，使用线程也不会加速计算。
|
||||
|
||||
但当你需要并行化到多核时，你不需要放弃使用 Python：[Dask][3] 库可以将计算扩展到多个内核甚至多个机器。某些设置可以在数千台机器上配置 Dask，每台机器都有多个内核。虽然存在扩展规模的限制，但一般达不到。
|
||||
|
||||
虽然 Dask 有许多内置的数组操作，但举一个非内置的例子，我们可以计算[偏度][4]：
|
||||
|
||||
```
|
||||
import numpy
|
||||
import dask
|
||||
from dask import array as darray
|
||||
|
||||
arr = dask.from_array(numpy.array(my_data), chunks=(1000,))
|
||||
mean = darray.mean()
|
||||
stddev = darray.std(arr)
|
||||
unnormalized_moment = darry.mean(arr * arr * arr)
|
||||
## See formula in wikipedia:
|
||||
skewness = ((unnormalized_moment - (3 * mean * stddev ** 2) - mean ** 3) /
|
||||
stddev ** 3)
|
||||
```
|
||||
|
||||
请注意，每个操作将根据需要使用尽可能多的内核。这将在所有核心上并行化执行，即使在计算数十亿个元素时也是如此。
|
||||
|
||||
当然，并不是我们所有的操作都可由这个库并行化，有时我们需要自己实现并行性。
|
||||
|
||||
为此，Dask 有一个“延迟”功能：
|
||||
|
||||
```
|
||||
import dask
|
||||
|
||||
def is_palindrome(s):
|
||||
return s == s[::-1]
|
||||
|
||||
palindromes = [dask.delayed(is_palindrome)(s) for s in string_list]
|
||||
total = dask.delayed(sum)(palindromes)
|
||||
result = total.compute()
|
||||
```
|
||||
|
||||
这将计算字符串是否是回文并返回回文的数量。
|
||||
|
||||
虽然 Dask 是为数据科学家创建的，但它绝不仅限于数据科学。每当我们需要在 Python 中并行化任务时，我们可以使用 Dask —— 无论有没有 GIL。
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/19/4/parallel-computation-python-dask
|
||||
|
||||
作者：[Moshe Zadka (Community Moderator)][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[geekpi](https://github.com/geekpi)
|
||||
校对：[wxy](https://github.com/wxy)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://opensource.com/users/moshez
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/collab-team-pair-programming-code-keyboard.png?itok=kBeRTFL1 (Pair programming)
|
||||
[2]: https://wiki.python.org/moin/GlobalInterpreterLock
|
||||
[3]: https://github.com/dask/dask
|
||||
[4]: https://en.wikipedia.org/wiki/Skewness#Definition
|
||||
@@ -0,0 +1,89 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: (tomjlw)
|
||||
[#]: reviewer: (wxy)
|
||||
[#]: publisher: (wxy)
|
||||
[#]: url: (https://linux.cn/article-10741-1.html)
|
||||
[#]: subject: (Streaming internet radio with RadioDroid)
|
||||
[#]: via: (https://opensource.com/article/19/4/radiodroid-internet-radio-player)
|
||||
[#]: author: (Chris Hermansen (Community Moderator) https://opensource.com/users/clhermansen)
|
||||
|
||||
使用 RadioDroid 流传输网络广播
|
||||
======
|
||||
|
||||
> 通过简单的设置使用你家中的音响收听你最爱的网络电台。
|
||||
|
||||
![][1]
|
||||
|
||||
最近网络媒体对 [Google 的 Chromecast 音频设备的下架][2]发出叹息。该设备在音频媒体界备受[好评][3]，因此我已经在考虑入手一个。基于 Chromecast 退场的消息，我决定在它们全部被打包扔进垃圾堆之前以一个合理价位买一个。
|
||||
|
||||
我在 [MobileFun][4] 上找到一个放进我的订单中。这个设备最终到货了。它被包在一个普普通通、简简单单的 Google 包装袋中，外面打印着非常简短的使用指南。
|
||||
|
||||
![Google Chromecast 音频][5]
|
||||
|
||||
我通过我的数模转换器的光纤 S/PDIF 连接接入到家庭音响，希望以此能提供最佳的音质。
|
||||
|
||||
安装过程并无纰漏，在五分钟后我就可以播放一些音乐了。我知道一些安卓应用支持 Chromecast，因此我决定用 Google Play Music 测试它。意料之中，它工作得不错，音乐效果听上去也相当好。然而作为一个具有开源精神的人，我决定看看我能找到什么开源播放器能兼容 Chromecast。
|
||||
|
||||
### RadioDroid 的救赎
|
||||
|
||||
[RadioDroid 安卓应用][6] 满足条件。它是开源的，并且可从 [GitHub][7]、Google Play 以及 [F-Droid][8] 上获取。根据帮助文档，RadioDroid 从 [Community Radio Browser][9] 网页寻找播放流。因此我决定在我的手机上安装尝试一下。
|
||||
|
||||
![RadioDroid][10]
|
||||
|
||||
安装过程快速顺利，RadioDroid 打开展示当地电台十分迅速。你可以在这个屏幕截图的右上方附近看到 Chromecast 按钮（看上去像一个有着波阵面的长方形图标）。
|
||||
|
||||
我尝试了几个当地电台。这个应用可靠地在我手机喇叭上播放了音乐。但是我不得不摆弄 Chromecast 按钮来通过 Chromecast 把音乐传到流上。但是它确实可以做到流传输。
|
||||
|
||||
我决定找一下我喜爱的网络广播电台：法国马赛的 [格雷诺耶广播电台][11]。在 RadioDroid 上有许多找到电台的方法。其中一种是使用标签——“当地”、“最流行”等——就在电台列表上方。其中一个标签是国家，我找到法国，在其 1500 个电台中划来划去寻找格雷诺耶广播电台。另一种办法是使用屏幕上方的查询按钮；查询迅速找到了那家美妙的电台。我尝试了其它几次查询它们都返回了合理的信息。
|
||||
|
||||
回到“当地”标签，我在列表中翻来覆去，发现“当地”的定义似乎是“在同一个国家”。因此尽管西雅图、波特兰、旧金山、洛杉矶和朱诺比多伦多更靠近我的家，我并没有在“当地”标签中看到它们。然而通过使用查询功能，我可以发现所有名字中带有西雅图的电台。
|
||||
|
||||
“语言”标签使我找到所有用葡语（及葡语方言）播报的电台。我很快发现了另一个最爱的电台 [91 Rock Curitiba][12]。
|
||||
|
||||
接着灵感来了，虽然现在是春天了，但又如何呢？让我们听一些圣诞音乐。意料之中，搜寻圣诞把我引到了 [181.FM – Christmas Blender][13]。不错，一两分钟的欣赏对我就够了。
|
||||
|
||||
因此总的来说，我推荐把 RadioDroid 和 Chromecast 的组合作为一种用家庭音响以合理价位播放网络电台的良好方式。
|
||||
|
||||
### 对于音乐方面……
|
||||
|
||||
最近我从 [Blue Coast Music][16] 商店里选了一个 [Qua Continuum][15] 创作的叫作 [Continuum One][14] 的有趣的氛围（甚至无节拍）音乐专辑。
|
||||
|
||||
Blue Coast 有许多可提供给开源音乐爱好者的。音乐可以无需通过那些奇怪的平台专用下载管理器下载（有时以物理形式）。它通常提供几种形式，包括 WAV、FLAC 和 DSD；WAV 和 FLAC 还提供不同的字长和比特率，包括 16/44.1、24/96 和 24/192，针对 DSD 则有 2.8、5.6 和 11.2 MHz。音乐是用优秀的仪器精心录制的。不幸的是，我并没有找到许多符合我口味的音乐，尽管我喜欢 Blue Coast 上能获取的几个艺术家，包括 Qua Continuum，[Art Lande][17] 以及 [Alex De Grassi][18]。
|
||||
|
||||
在 [Bandcamp][19] 上，我挑选了 [Emancipator's Baralku][20] 和 [Framework's Tides][21]，两个都是我喜欢的。两位艺术家创作的音乐符合我的口味——电音但又（总体来说）不是舞蹈，它们的音乐旋律优美，副歌也很好听。有许多可以让开源音乐发烧友爱上 Bandcamp 的东西，比如买前试听整首歌的服务；没有垃圾软件下载器；与大量音乐家的合作；以及对 [Creative Commons music][22] 的支持。
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/19/4/radiodroid-internet-radio-player
|
||||
|
||||
作者：[Chris Hermansen (Community Moderator)][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[tomjlw](https://github.com/tomjlw)
|
||||
校对：[wxy](https://github.com/wxy)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://opensource.com/users/clhermansen
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/programming-code-keyboard-laptop-music-headphones.png?itok=EQZ2WKzy (woman programming)
|
||||
[2]: https://www.theverge.com/2019/1/11/18178751/google-chromecast-audio-discontinued-sale
|
||||
[3]: https://www.whathifi.com/google/chromecast-audio/review
|
||||
[4]: https://www.mobilefun.com/google-chromecast-audio-black-70476
|
||||
[5]: https://opensource.com/sites/default/files/uploads/internet-radio_chromecast.png (Google Chromecast Audio)
|
||||
[6]: https://play.google.com/store/apps/details?id=net.programmierecke.radiodroid2
|
||||
[7]: https://github.com/segler-alex/RadioDroid
|
||||
[8]: https://f-droid.org/en/packages/net.programmierecke.radiodroid2/
|
||||
[9]: http://www.radio-browser.info/gui/#!/
|
||||
[10]: https://opensource.com/sites/default/files/uploads/internet-radio_radiodroid.png (RadioDroid)
|
||||
[11]: http://www.radiogrenouille.com/
|
||||
[12]: https://91rock.com.br/
|
||||
[13]: http://player.181fm.com/?station=181-xblender
|
||||
[14]: https://www.youtube.com/watch?v=PqLCQXPS8iQ
|
||||
[15]: https://bluecoastmusic.com/artists/qua-continuum
|
||||
[16]: https://bluecoastmusic.com/store
|
||||
[17]: https://bluecoastmusic.com/store?f%5B0%5D=search_api_multi_aggregation_1%3Aart%20lande
|
||||
[18]: https://bluecoastmusic.com/store?f%5B0%5D=search_api_multi_aggregation_1%3Aalex%20de%20grassi
|
||||
[19]: https://bandcamp.com/
|
||||
[20]: https://emancipator.bandcamp.com/album/baralku
|
||||
[21]: https://frameworksuk.bandcamp.com/album/tides
|
||||
[22]: https://bandcamp.com/tag/creative-commons
|
||||
@@ -0,0 +1,65 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: (MjSeven)
|
||||
[#]: reviewer: (wxy)
|
||||
[#]: publisher: (wxy)
|
||||
[#]: url: (https://linux.cn/article-10725-1.html)
|
||||
[#]: subject: (Bash vs. Python: Which language should you use?)
|
||||
[#]: via: (https://opensource.com/article/19/4/bash-vs-python)
|
||||
[#]: author: (Archit Modi Red Hat https://opensource.com/users/architmodi/users/greg-p/users/oz123)
|
||||
|
||||
Bash vs Python：你该使用哪个？
|
||||
======
|
||||
|
||||
> 两种编程语言都各有优缺点，它们在某些任务方面互有胜负。
|
||||
|
||||
![][1]
|
||||
|
||||
[Bash][2] 和 [Python][3] 是大多数自动化工程师最喜欢的编程语言。它们都各有优缺点，有时很难选择应该使用哪一个。所以，最诚实的答案是：这取决于任务、范围、背景和任务的复杂性。
|
||||
|
||||
让我们来比较一下这两种语言，以便更好地理解它们各自的优点。
|
||||
|
||||
### Bash
|
||||
|
||||
* 是一种 Linux/Unix shell 命令语言
|
||||
* 非常适合编写使用命令行界面（CLI）实用程序的 shell 脚本，利用一个命令的输出传递给另一个命令（管道），以及执行简单的任务（可以多达 100 行代码）
|
||||
* 可以按原样使用命令行命令和实用程序
|
||||
* 启动时间比 Python 快，但执行时性能差
|
||||
* Windows 中默认没有安装。你的脚本可能不会兼容多个操作系统，但是 Bash 是大多数 Linux/Unix 系统的默认 shell
|
||||
* 与其它 shell (如 csh、zsh、fish) *不* 完全兼容。
|
||||
* 通过管道（`|`）传递 CLI 实用程序如 `sed`、`awk`、`grep` 等会降低其性能
|
||||
* 缺少很多函数、对象、数据结构和多线程支持，这限制了它在复杂脚本或编程中的使用
|
||||
* 缺少良好的调试工具和实用程序
|
||||
|
||||
### Python
|
||||
|
||||
* 是一种面对对象编程语言（OOP），因此它比 Bash 更加通用
|
||||
* 几乎可以用于任何任务
|
||||
* 适用于大多数操作系统，默认情况下它在大多数 Unix/Linux 系统中都有安装
|
||||
* 与伪代码非常相似
|
||||
* 具有简单、清晰、易于学习和阅读的语法
|
||||
* 拥有大量的库、文档以及一个活跃的社区
|
||||
* 提供比 Bash 更友好的错误处理特性
|
||||
* 有比 Bash 更好的调试工具和实用程序，这使得它在开发涉及到很多行代码的复杂软件应用程序时是一种很棒的语言
|
||||
* 应用程序（或脚本）可能包含许多第三方依赖项，这些依赖项必须在执行前安装
|
||||
* 对于简单任务，需要编写比 Bash 更多的代码
|
||||
|
||||
我希望这些列表能够让你更好地了解该使用哪种语言以及在何时使用它。
|
||||
|
||||
你在日常工作中更多会使用哪种语言，Bash 还是 Python？请在评论中分享。
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/19/4/bash-vs-python
|
||||
|
||||
作者：[Archit Modi (Red Hat)][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[MjSeven](https://github.com/MjSeven)
|
||||
校对：[wxy](https://github.com/wxy)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://opensource.com/users/architmodi/users/greg-p/users/oz123
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/computer_happy_sad_developer_programming.png?itok=72nkfSQ_
|
||||
[2]: /article/18/7/admin-guide-bash
|
||||
[3]: /article/17/11/5-approaches-learning-python
|
||||
@@ -0,0 +1,74 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: (tomjlw)
|
||||
[#]: reviewer: (wxy)
|
||||
[#]: publisher: (wxy)
|
||||
[#]: url: (https://linux.cn/article-10747-1.html)
|
||||
[#]: subject: (Cisco, Google reenergize multicloud/hybrid cloud joint development)
|
||||
[#]: via: (https://www.networkworld.com/article/3388218/cisco-google-reenergize-multicloudhybrid-cloud-joint-development.html#tk.rss_all)
|
||||
[#]: author: (Michael Cooney https://www.networkworld.com/author/Michael-Cooney/)
|
||||
|
||||
思科、谷歌重新赋能多/混合云共同开发
|
||||
======
|
||||
> 思科、VMware、HPE 等公司开始采用了新的 Google Cloud Athos 云技术。
|
||||
|
||||
![Thinkstock][1]
|
||||
|
||||
思科与谷歌已扩展它们的混合云开发活动，以帮助其客户可以在从本地数据中心到公共云上的任何地方更轻松地搭建安全的多云以及混合云应用。
|
||||
|
||||
这次扩张围绕着谷歌被称作 Anthos 的新的开源混合云包展开，它是在这周的 Google Next 活动上推出的。Anthos 基于并取代了谷歌现有的谷歌云服务测试版。Anthos 将让客户们无须修改应用就可以在现有的本地硬件或公共云上运行应用。据谷歌说，它可以在[谷歌云平台][5] (GCP) 与 [谷歌 Kubernetes 引擎][6] (GKE) 或者在数据中心中与 [GKE On-Prem][7] 一同使用。谷歌说，Anthos 首次让客户们可以无需管理员和开发者了解不同的坏境和 API 就能从谷歌平台上管理在第三方云上（如 AWS 和 Azure）的工作负荷。
|
||||
|
||||
关键在于，Athos 提供了一个单一的托管服务，它使得客户们无须担心不同的环境或 API 就能跨云管理、部署工作负荷。
|
||||
|
||||
作为首秀的一部分，谷歌也宣布一个叫做 [Anthos Migrate][8] 的测试计划，它能够从本地环境或者其它云自动迁移虚拟机到 GKE 上的容器中。谷歌说，“这种独特的迁移技术使你无须修改原来的虚拟机或者应用就能以一种行云流水般的方式迁移、更新你的基础设施”。谷歌称它给予了公司按客户节奏转移本地应用到云环境的灵活性。
|
||||
|
||||
### 思科和谷歌
|
||||
|
||||
就思科来说，它宣布对 Anthos 的支持并承诺将它紧密集成进思科的数据中心技术中，例如 HyperFlex 超融合包、应用中心基础设施（思科的旗舰 SDN 方案）、SD-WAN 和 StealthWatch 云。思科说，无论是本地的还是在云端的，这次集成将通过自动更新到最新版本和安全补丁，给予一种一致的、云般的感觉。
|
||||
|
||||
“谷歌云在容器（Kubernetes）和<ruby>服务网格<rt>service mesh</rt></ruby>（Istio）上的专业与它们在开发者社区的领导力，再加上思科的企业级网络、计算、存储和安全产品及服务，将为我们的顾客促成一次强强联合。”思科的云平台和解决方案集团资深副总裁 Kip Compton 这样[写道][9]，“思科对于 Anthos 的集成将会帮助顾客跨本地数据中心和公共云搭建、管理多云/混合云应用，让他们专注于创新和灵活性，同时不会影响安全性或增加复杂性。”
|
||||
|
||||
### 谷歌云和思科
|
||||
|
||||
谷歌云工程副总裁 Eyal Manor [写道][10] 通过思科对 Anthos 的支持，客户将能够：
|
||||
|
||||
* 受益于全托管服务例如 GKE 以及思科的超融合基础设施、网络和安全技术；
|
||||
* 在企业数据中心和云中一致运行
|
||||
* 在企业数据中心使用云服务
|
||||
* 用最新的云技术更新本地基础设施
|
||||
|
||||
思科和谷歌从 2017 年 10 月就在紧密合作，当时他们表示正在开发一个能够连接本地基础设施和云环境的开放混合云平台。该套件，即[思科为谷歌云打造的混合云平台][11]，大致在 2018 年 9 月上市。它使得客户们能通过谷歌云托管 Kubernetes 容器开发企业级功能，包含思科网络和安全技术以及来自 Istio 的服务网格监控。
|
||||
|
||||
谷歌说开源的 Istio 的容器和微服务优化技术给开发者提供了一种一致的方式，通过服务级的 mTLS （双向传输层安全）身份验证访问控制来跨云连接、保护、管理和监听微服务。因此，客户能够轻松实施新的可移植的服务，并集中配置和管理这些服务。
|
||||
|
||||
思科不是唯一宣布对 Anthos 支持的供应商。谷歌表示，至少 30 家大型合作商包括 [VMware][12]、[Dell EMC][13]、[HPE][14]、Intel 和联想致力于为他们的客户在它们自己的超融合基础设施上提供 Anthos 服务。
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.networkworld.com/article/3388218/cisco-google-reenergize-multicloudhybrid-cloud-joint-development.html
|
||||
|
||||
作者：[Michael Cooney][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[tomjlw](https://github.com/tomjlw)
|
||||
校对：[wxy](https://github.com/wxy)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://www.networkworld.com/author/Michael-Cooney/
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://images.techhive.com/images/article/2016/12/hybrid_cloud-100700390-large.jpg
|
||||
[2]: https://www.networkworld.com/article/3233132/cloud-computing/what-is-hybrid-cloud-computing.html
|
||||
[3]: https://www.networkworld.com/article/3252775/hybrid-cloud/multicloud-mania-what-to-know.html
|
||||
[4]: https://www.networkworld.com/newsletters/signup.html
|
||||
[5]: https://cloud.google.com/
|
||||
[6]: https://cloud.google.com/kubernetes-engine/
|
||||
[7]: https://cloud.google.com/gke-on-prem/
|
||||
[8]: https://cloud.google.com/contact/
|
||||
[9]: https://blogs.cisco.com/news/next-phase-cisco-google-cloud
|
||||
[10]: https://cloud.google.com/blog/topics/partners/google-cloud-partners-with-cisco-on-hybrid-cloud-next19?utm_medium=unpaidsocial&utm_campaign=global-googlecloud-liveevent&utm_content=event-next
|
||||
[11]: https://cloud.google.com/cisco/
|
||||
[12]: https://blogs.vmware.com/networkvirtualization/2019/04/vmware-and-google-showcase-hybrid-cloud-deployment.html/
|
||||
[13]: https://www.dellemc.com/en-us/index.htm
|
||||
[14]: https://www.hpe.com/us/en/newsroom/blog-post/2019/04/hpe-and-google-cloud-join-forces-to-accelerate-innovation-with-hybrid-cloud-solutions-optimized-for-containerized-applications.html
|
||||
[15]: https://www.facebook.com/NetworkWorld/
|
||||
[16]: https://www.linkedin.com/company/network-world
|
||||
|
||||
@@ -0,0 +1,231 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: (heguangzhi)
|
||||
[#]: reviewer: (wxy)
|
||||
[#]: publisher: (wxy)
|
||||
[#]: url: (https://linux.cn/article-10736-1.html)
|
||||
[#]: subject: (How To Check The List Of Open Ports In Linux?)
|
||||
[#]: via: (https://www.2daygeek.com/linux-scan-check-open-ports-using-netstat-ss-nmap/)
|
||||
[#]: author: (Magesh Maruthamuthu https://www.2daygeek.com/author/magesh/)
|
||||
|
||||
如何检查 Linux 中的开放端口列表？
|
||||
======
|
||||
|
||||
最近，我们就同一主题写了两篇文章。这些文章内容帮助你如何检查远程服务器中给定的端口是否打开。
|
||||
|
||||
如果你想 [检查远程 Linux 系统上的端口是否打开][1] 请点击链接浏览。如果你想 [检查多个远程 Linux 系统上的端口是否打开][2] 请点击链接浏览。如果你想 [检查多个远程 Linux 系统上的多个端口状态][2] 请点击链接浏览。
|
||||
|
||||
但是本文帮助你检查本地系统上的开放端口列表。
|
||||
|
||||
在 Linux 中很少有用于此目的的实用程序。然而，我提供了四个最重要的 Linux 命令来检查这一点。
|
||||
|
||||
你可以使用以下四个命令来完成这个工作。这些命令是非常出名的并被 Linux 管理员广泛使用。
|
||||
|
||||
* `netstat`：netstat (“network statistics”) 是一个显示网络连接（进和出）相关信息命令行工具，例如：路由表, 伪装连接,多点传送成员和网络端口。
|
||||
* `nmap`：Nmap (“Network Mapper”) 是一个网络探索与安全审计的开源工具。它旨在快速扫描大型网络。
|
||||
* `ss`： ss 被用于转储套接字统计信息。它也可以类似 netstat 使用。相比其他工具它可以展示更多的TCP状态信息。
|
||||
* `lsof`： lsof 是 List Open File 的缩写. 它用于输出被某个进程打开的所有文件。
|
||||
|
||||
### 如何使用 Linux 命令 netstat 检查系统中的开放端口列表
|
||||
|
||||
`netstat` 是 Network Statistics 的缩写，是一个显示网络连接（进和出）相关信息命令行工具，例如：路由表、伪装连接、多播成员和网络端口。
|
||||
|
||||
它可以列出所有的 tcp、udp 连接和所有的 unix 套接字连接。
|
||||
|
||||
它用于发现发现网络问题，确定网络连接数量。
|
||||
|
||||
```
|
||||
# netstat -tplugn
|
||||
|
||||
Active Internet connections (only servers)
|
||||
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
|
||||
tcp 0 0 0.0.0.0:25 0.0.0.0:* LISTEN 2038/master
|
||||
tcp 0 0 127.0.0.1:199 0.0.0.0:* LISTEN 1396/snmpd
|
||||
tcp 0 0 0.0.0.0:80 0.0.0.0:* LISTEN 1398/httpd
|
||||
tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 1388/sshd
|
||||
tcp6 0 0 :::25 :::* LISTEN 2038/master
|
||||
tcp6 0 0 :::22 :::* LISTEN 1388/sshd
|
||||
udp 0 0 0.0.0.0:39136 0.0.0.0:* 1396/snmpd
|
||||
udp 0 0 0.0.0.0:56130 0.0.0.0:* 1396/snmpd
|
||||
udp 0 0 0.0.0.0:40105 0.0.0.0:* 1396/snmpd
|
||||
udp 0 0 0.0.0.0:11584 0.0.0.0:* 1396/snmpd
|
||||
udp 0 0 0.0.0.0:30105 0.0.0.0:* 1396/snmpd
|
||||
udp 0 0 0.0.0.0:50656 0.0.0.0:* 1396/snmpd
|
||||
udp 0 0 0.0.0.0:1632 0.0.0.0:* 1396/snmpd
|
||||
udp 0 0 0.0.0.0:28265 0.0.0.0:* 1396/snmpd
|
||||
udp 0 0 0.0.0.0:40764 0.0.0.0:* 1396/snmpd
|
||||
udp 0 0 10.90.56.21:123 0.0.0.0:* 895/ntpd
|
||||
udp 0 0 127.0.0.1:123 0.0.0.0:* 895/ntpd
|
||||
udp 0 0 0.0.0.0:123 0.0.0.0:* 895/ntpd
|
||||
udp 0 0 0.0.0.0:53390 0.0.0.0:* 1396/snmpd
|
||||
udp 0 0 0.0.0.0:161 0.0.0.0:* 1396/snmpd
|
||||
udp6 0 0 :::123 :::* 895/ntpd
|
||||
|
||||
IPv6/IPv4 Group Memberships
|
||||
Interface RefCnt Group
|
||||
--------------- ------ ---------------------
|
||||
lo 1 224.0.0.1
|
||||
eth0 1 224.0.0.1
|
||||
lo 1 ff02::1
|
||||
lo 1 ff01::1
|
||||
eth0 1 ff02::1
|
||||
eth0 1 ff01::1
|
||||
```
|
||||
|
||||
你也可以使用下面的命令检查特定的端口。
|
||||
|
||||
```
|
||||
# # netstat -tplugn | grep :22
|
||||
|
||||
tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 1388/sshd
|
||||
tcp6 0 0 :::22 :::* LISTEN 1388/sshd
|
||||
```
|
||||
|
||||
### 如何使用 Linux 命令 ss 检查系统中的开放端口列表？
|
||||
|
||||
`ss` 被用于转储套接字统计信息。它也可以显示类似 `netstat` 的信息。相比其他工具它可以展示更多的 TCP 状态信息。
|
||||
|
||||
```
|
||||
# ss -lntu
|
||||
|
||||
Netid State Recv-Q Send-Q Local Address:Port Peer Address:Port
|
||||
udp UNCONN 0 0 *:39136 *:*
|
||||
udp UNCONN 0 0 *:56130 *:*
|
||||
udp UNCONN 0 0 *:40105 *:*
|
||||
udp UNCONN 0 0 *:11584 *:*
|
||||
udp UNCONN 0 0 *:30105 *:*
|
||||
udp UNCONN 0 0 *:50656 *:*
|
||||
udp UNCONN 0 0 *:1632 *:*
|
||||
udp UNCONN 0 0 *:28265 *:*
|
||||
udp UNCONN 0 0 *:40764 *:*
|
||||
udp UNCONN 0 0 10.90.56.21:123 *:*
|
||||
udp UNCONN 0 0 127.0.0.1:123 *:*
|
||||
udp UNCONN 0 0 *:123 *:*
|
||||
udp UNCONN 0 0 *:53390 *:*
|
||||
udp UNCONN 0 0 *:161 *:*
|
||||
udp UNCONN 0 0 :::123 :::*
|
||||
tcp LISTEN 0 100 *:25 *:*
|
||||
tcp LISTEN 0 128 127.0.0.1:199 *:*
|
||||
tcp LISTEN 0 128 *:80 *:*
|
||||
tcp LISTEN 0 128 *:22 *:*
|
||||
tcp LISTEN 0 100 :::25 :::*
|
||||
tcp LISTEN 0 128 :::22 :::*
|
||||
```
|
||||
|
||||
你也可以使用下面的命令检查特定的端口。
|
||||
|
||||
```
|
||||
# # ss -lntu | grep ':25'
|
||||
|
||||
tcp LISTEN 0 100 *:25 *:*
|
||||
tcp LISTEN 0 100 :::25 :::*
|
||||
```
|
||||
|
||||
### 如何使用 Linux 命令 nmap 检查系统中的开放端口列表？
|
||||
|
||||
Nmap (“Network Mapper”) 是一个网络探索与安全审计的开源工具。它旨在快速扫描大型网络，当然它也可以工作在独立主机上。
|
||||
|
||||
Nmap 使用裸 IP 数据包以一种新颖的方式来确定网络上有哪些主机可用，这些主机提供什么服务（应用程序名称和版本），它们运行什么操作系统（版本），使用什么类型的数据包过滤器/防火墙，以及许多其他特征。
|
||||
|
||||
虽然 Nmap 通常用于安全审计，但许多系统和网络管理员发现它对于日常工作也非常有用，例如网络资产清点、管理服务升级计划以及监控主机或服务正常运行时间。
|
||||
|
||||
```
|
||||
# nmap -sTU -O localhost
|
||||
|
||||
Starting Nmap 6.40 ( http://nmap.org ) at 2019-03-20 09:57 CDT
|
||||
Nmap scan report for localhost (127.0.0.1)
|
||||
Host is up (0.00028s latency).
|
||||
Other addresses for localhost (not scanned): 127.0.0.1
|
||||
Not shown: 1994 closed ports
|
||||
|
||||
PORT STATE SERVICE
|
||||
22/tcp open ssh
|
||||
25/tcp open smtp
|
||||
80/tcp open http
|
||||
199/tcp open smux
|
||||
123/udp open ntp
|
||||
161/udp open snmp
|
||||
|
||||
Device type: general purpose
|
||||
Running: Linux 3.X
|
||||
OS CPE: cpe:/o:linux:linux_kernel:3
|
||||
OS details: Linux 3.7 - 3.9
|
||||
Network Distance: 0 hops
|
||||
|
||||
OS detection performed. Please report any incorrect results at http://nmap.org/submit/ .
|
||||
Nmap done: 1 IP address (1 host up) scanned in 1.93 seconds
|
||||
```
|
||||
|
||||
你也可以使用下面的命令检查特定的端口。
|
||||
|
||||
```
|
||||
# nmap -sTU -O localhost | grep 123
|
||||
|
||||
123/udp open ntp
|
||||
```
|
||||
|
||||
### 如何使用 Linux 命令 lsof 检查系统中的开放端口列表？
|
||||
|
||||
它向你显示系统上打开的文件列表以及打开它们的进程。还会向你显示与文件相关的其他信息。
|
||||
|
||||
```
|
||||
# lsof -i
|
||||
|
||||
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
|
||||
ntpd 895 ntp 16u IPv4 18481 0t0 UDP *:ntp
|
||||
ntpd 895 ntp 17u IPv6 18482 0t0 UDP *:ntp
|
||||
ntpd 895 ntp 18u IPv4 18487 0t0 UDP localhost:ntp
|
||||
ntpd 895 ntp 20u IPv4 23020 0t0 UDP CentOS7.2daygeek.com:ntp
|
||||
sshd 1388 root 3u IPv4 20065 0t0 TCP *:ssh (LISTEN)
|
||||
sshd 1388 root 4u IPv6 20067 0t0 TCP *:ssh (LISTEN)
|
||||
snmpd 1396 root 6u IPv4 22739 0t0 UDP *:snmp
|
||||
snmpd 1396 root 7u IPv4 22729 0t0 UDP *:40105
|
||||
snmpd 1396 root 8u IPv4 22730 0t0 UDP *:50656
|
||||
snmpd 1396 root 9u IPv4 22731 0t0 UDP *:pammratc
|
||||
snmpd 1396 root 10u IPv4 22732 0t0 UDP *:30105
|
||||
snmpd 1396 root 11u IPv4 22733 0t0 UDP *:40764
|
||||
snmpd 1396 root 12u IPv4 22734 0t0 UDP *:53390
|
||||
snmpd 1396 root 13u IPv4 22735 0t0 UDP *:28265
|
||||
snmpd 1396 root 14u IPv4 22736 0t0 UDP *:11584
|
||||
snmpd 1396 root 15u IPv4 22737 0t0 UDP *:39136
|
||||
snmpd 1396 root 16u IPv4 22738 0t0 UDP *:56130
|
||||
snmpd 1396 root 17u IPv4 22740 0t0 TCP localhost:smux (LISTEN)
|
||||
httpd 1398 root 3u IPv4 20337 0t0 TCP *:http (LISTEN)
|
||||
master 2038 root 13u IPv4 21638 0t0 TCP *:smtp (LISTEN)
|
||||
master 2038 root 14u IPv6 21639 0t0 TCP *:smtp (LISTEN)
|
||||
sshd 9052 root 3u IPv4 1419955 0t0 TCP CentOS7.2daygeek.com:ssh->Ubuntu18-04.2daygeek.com:11408 (ESTABLISHED)
|
||||
httpd 13371 apache 3u IPv4 20337 0t0 TCP *:http (LISTEN)
|
||||
httpd 13372 apache 3u IPv4 20337 0t0 TCP *:http (LISTEN)
|
||||
httpd 13373 apache 3u IPv4 20337 0t0 TCP *:http (LISTEN)
|
||||
httpd 13374 apache 3u IPv4 20337 0t0 TCP *:http (LISTEN)
|
||||
httpd 13375 apache 3u IPv4 20337 0t0 TCP *:http (LISTEN)
|
||||
```
|
||||
|
||||
你也可以使用下面的命令检查特定的端口。
|
||||
|
||||
```
|
||||
# lsof -i:80
|
||||
|
||||
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
|
||||
httpd 1398 root 3u IPv4 20337 0t0 TCP *:http (LISTEN)
|
||||
httpd 13371 apache 3u IPv4 20337 0t0 TCP *:http (LISTEN)
|
||||
httpd 13372 apache 3u IPv4 20337 0t0 TCP *:http (LISTEN)
|
||||
httpd 13373 apache 3u IPv4 20337 0t0 TCP *:http (LISTEN)
|
||||
httpd 13374 apache 3u IPv4 20337 0t0 TCP *:http (LISTEN)
|
||||
httpd 13375 apache 3u IPv4 20337 0t0 TCP *:http (LISTEN)
|
||||
```
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.2daygeek.com/linux-scan-check-open-ports-using-netstat-ss-nmap/
|
||||
|
||||
作者：[Magesh Maruthamuthu][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[heguangzhi](https://github.com/heguangzhi)
|
||||
校对：[wxy](https://github.com/wxy)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://www.2daygeek.com/author/magesh/
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://linux.cn/article-10675-1.html
|
||||
[2]: https://www.2daygeek.com/check-a-open-port-on-multiple-remote-linux-server-using-nc-command/
|
||||
443
published/20190413 The Fargate Illusion.md
Normal file
443
published/20190413 The Fargate Illusion.md
Normal file
@@ -0,0 +1,443 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: (wxy)
|
||||
[#]: reviewer: (wxy)
|
||||
[#]: publisher: (wxy)
|
||||
[#]: url: (https://linux.cn/article-10740-1.html)
|
||||
[#]: subject: (The Fargate Illusion)
|
||||
[#]: via: (https://leebriggs.co.uk/blog/2019/04/13/the-fargate-illusion.html)
|
||||
[#]: author: (Lee Briggs https://leebriggs.co.uk/)
|
||||
|
||||
破除对 AWS Fargate 的幻觉
|
||||
======
|
||||
|
||||
我在 $work 建立了一个基于 Kubernetes 的平台已经快一年了，而且有点像 Kubernetes 的布道者了。真的，我认为这项技术太棒了。然而我并没有对它的运营和维护的困难程度抱过什么幻想。今年早些时候我读了[这样][1]的一篇文章，并对其中某些观点深以为然。如果我在一家规模较小的、有 10 到 15 个工程师的公司，假如有人建议管理和维护一批 Kubernetes 集群，那我会感到害怕的，因为它的运维开销太高了！
|
||||
|
||||
尽管我现在对 Kubernetes 的一切都很感兴趣，但我仍然对“<ruby>无服务器<rt>Serverless</rt></ruby>”计算会消灭运维工程师的说法抱有好奇。这种好奇心主要来源于我希望在未来仍然能有一份有报酬的工作 —— 如果我们前景光明的未来不需要运维工程师，那我得明白到底是怎么回事。我已经在 Lamdba 和Google Cloud Functions 上做了一些实验，结果让我印象十分深刻，但我仍然坚信无服务器解决方案只是解决了一部分问题。
|
||||
|
||||
我关注 [AWS Fargate][2] 已经有一段时间了，这就是 $work 的开发人员所推崇为“无服务器计算”的东西 —— 主要是因为 Fargate，用它你就可以无需管理底层节点而运行你的 Docker 容器。我想看看它到底意味着什么，所以我开始尝试从头开始在 Fargate 上运行一个应用，看看是否可以成功。这里我对成功的定义是一个与“生产级”应用程序相近的东西，我想应该包含以下内容：
|
||||
|
||||
* 一个在 Fargate 上运行的容器
|
||||
* 配置信息以环境变量的形式下推
|
||||
* “秘密信息” 不能是明文的
|
||||
* 位于负载均衡器之后
|
||||
* 有效的 SSL 证书的 TLS 通道
|
||||
|
||||
我以“基础设施即代码”的角度来开始整个任务，不遵循默认的 AWS 控制台向导，而是使用 terraform 来定义基础架构。这很可能让整个事情变得复杂，但我想确保任何部署都是可重现的，任何想要遵循此步骤的人都可发现我的结论。
|
||||
|
||||
上述所有标准通常都可以通过基于 Kubernetes 的平台使用一些外部的附加组件和插件来实现，所以我确实是以一种比较的心态来处理整个任务的，因为我要将它与我的常用工作流程进行比较。我的主要目标是看看Fargate 有多容易，特别是与 Kubernetes 相比时。结果让我感到非常惊讶。
|
||||
|
||||
### AWS 是有开销的
|
||||
|
||||
我有一个干净的 AWS 账户，并决定从零到部署一个 webapp。与 AWS 中的其它基础设施一样，我必须首先使基本的基础设施正常工作起来，因此我需要先定义一个 VPC。
|
||||
|
||||
遵循最佳实践，因此我将这个 VPC 划分为跨可用区（AZ）的子网，一个公共子网和私有子网。这时我想到，只要这种设置基础设施的需求存在，我就能找到一份这种工作。AWS 是"免"运维的这一概念一直让我感到愤怒。开发者社区中的许多人理所当然地认为在设置和定义一个设计良好的 AWS 账户和基础设施是不需要付出多少工作和努力的。而这种想当然甚至发生在开始谈论多帐户架构*之前*就有了——现在我仍然使用单一帐户，我已经必须定义好基础设施和传统的网络设备。
|
||||
|
||||
这里也值得记住，我已经做了很多次，所以我*很清楚*该做什么。我可以在我的帐户中使用默认的 VPC 以及预先提供的子网，我觉得很多刚开始的人也可以使用它。这大概花了我半个小时才运行起来，但我不禁想到，即使我想运行 lambda 函数，我仍然需要某种连接和网络。定义 NAT 网关和在 VPC 中路由根本不会让你觉得很“Serverless”，但要往下进行这就是必须要做的。
|
||||
|
||||
### 运行简单的容器
|
||||
|
||||
在我启动运行了基本的基础设施之后，现在我想让我的 Docker 容器运行起来。我开始翻阅 Fargate 文档并浏览 [入门][3] 文档，这些就马上就展现在了我面前：
|
||||
|
||||
![][4]
|
||||
|
||||
等等，只是让我的容器运行就至少要有**三个**步骤？这完全不像我所想的，不过还是让我们开始吧。
|
||||
|
||||
#### 任务定义
|
||||
|
||||
“<ruby>任务定义<rt>Task Definition<rt></ruby>”用来定义要运行的实际容器。我在这里遇到的问题是，任务定义这件事非常复杂。这里有很多选项都很简单，比如指定 Docker 镜像和内存限制，但我还必须定义一个网络模型以及我并不熟悉的其它各种选项。真需要这样吗？如果我完全没有 AWS 方面的知识就进入到这个过程里，那么在这个阶段我会感觉非常的不知所措。可以在 AWS 页面上找到这些 [参数][5] 的完整列表，这个列表很长。我知道我的容器需要一些环境变量，它需要暴露一个端口。所以我首先在一个神奇的 [terraform 模块][6] 的帮助下定义了这一点，这真的让这件事更容易了。如果没有这个模块，我就得手写 JSON 来定义我的容器定义。
|
||||
|
||||
首先我定义了一些环境变量：
|
||||
|
||||
```
|
||||
container_environment_variables = [
|
||||
{
|
||||
name = "USER"
|
||||
value = "${var.user}"
|
||||
},
|
||||
{
|
||||
name = "PASSWORD"
|
||||
value = "${var.password}"
|
||||
}
|
||||
]
|
||||
```
|
||||
|
||||
然后我使用上面提及的模块组成了任务定义：
|
||||
|
||||
```
|
||||
module "container_definition_app" {
|
||||
source = "cloudposse/ecs-container-definition/aws"
|
||||
version = "v0.7.0"
|
||||
|
||||
container_name = "${var.name}"
|
||||
container_image = "${var.image}"
|
||||
|
||||
container_cpu = "${var.ecs_task_cpu}"
|
||||
container_memory = "${var.ecs_task_memory}"
|
||||
container_memory_reservation = "${var.container_memory_reservation}"
|
||||
|
||||
port_mappings = [
|
||||
{
|
||||
containerPort = "${var.app_port}"
|
||||
hostPort = "${var.app_port}"
|
||||
protocol = "tcp"
|
||||
},
|
||||
]
|
||||
|
||||
environment = "${local.container_environment_variables}"
|
||||
|
||||
}
|
||||
```
|
||||
|
||||
在这一点上我非常困惑，我需要在这里定义很多配置才能运行，而这时什么都没有开始呢，但这是必要的 —— 运行 Docker 容器肯定需要了解一些容器配置的知识。我 [之前写过][7] 关于 Kubernetes 和配置管理的问题的文章，在这里似乎遇到了同样的问题。
|
||||
|
||||
接下来，我在上面的模块中定义了任务定义（幸好从我这里抽象出了所需的 JSON —— 如果我不得不手写JSON，我可能已经放弃了）。
|
||||
|
||||
当我定义模块参数时，我突然意识到我漏掉了一些东西。我需要一个 IAM 角色！好吧，让我来定义：
|
||||
|
||||
```
|
||||
resource "aws_iam_role" "ecs_task_execution" {
|
||||
name = "${var.name}-ecs_task_execution"
|
||||
|
||||
assume_role_policy = <<EOF
|
||||
{
|
||||
"Version": "2008-10-17",
|
||||
"Statement": [
|
||||
{
|
||||
"Action": "sts:AssumeRole",
|
||||
"Principal": {
|
||||
"Service": "ecs-tasks.amazonaws.com"
|
||||
},
|
||||
"Effect": "Allow"
|
||||
}
|
||||
]
|
||||
}
|
||||
EOF
|
||||
}
|
||||
|
||||
resource "aws_iam_role_policy_attachment" "ecs_task_execution" {
|
||||
count = "${length(var.policies_arn)}"
|
||||
|
||||
role = "${aws_iam_role.ecs_task_execution.id}"
|
||||
policy_arn = "${element(var.policies_arn, count.index)}"
|
||||
}
|
||||
```
|
||||
|
||||
这样做是有意义的，我需要在 Kubernetes 中定义一个 RBAC 策略，所以在这里我还未完全错失或获得任何东西。这时我开始觉得从 Kubernetes 的角度来看，这种感觉非常熟悉。
|
||||
|
||||
```
|
||||
resource "aws_ecs_task_definition" "app" {
|
||||
family = "${var.name}"
|
||||
network_mode = "awsvpc"
|
||||
requires_compatibilities = ["FARGATE"]
|
||||
cpu = "${var.ecs_task_cpu}"
|
||||
memory = "${var.ecs_task_memory}"
|
||||
execution_role_arn = "${aws_iam_role.ecs_task_execution.arn}"
|
||||
task_role_arn = "${aws_iam_role.ecs_task_execution.arn}"
|
||||
|
||||
container_definitions = "${module.container_definition_app.json}"
|
||||
|
||||
}
|
||||
```
|
||||
|
||||
现在，为了运行起来我已经写了很多行代码，我阅读了很多 ECS 文档，我所做的就是定义一个任务定义。我还没有让这个东西运行起来。在这一点上，我真的很困惑这个基于 Kubernetes 的平台到底增值了什么，但我继续前行。
|
||||
|
||||
#### 服务
|
||||
|
||||
服务，一定程度上是将容器如何暴露给外部，另外是如何定义它拥有的副本数量。我的第一个想法是“啊！这就像一个 Kubernetes 服务！”我开始着手映射端口等。这是我第一次在 terraform 上跑：
|
||||
|
||||
```
|
||||
resource "aws_ecs_service" "app" {
|
||||
name = "${var.name}"
|
||||
cluster = "${module.ecs.this_ecs_cluster_id}"
|
||||
task_definition = "${data.aws_ecs_task_definition.app.family}:${max(aws_ecs_task_definition.app.revision, data.aws_ecs_task_definition.app.revision)}"
|
||||
desired_count = "${var.ecs_service_desired_count}"
|
||||
launch_type = "FARGATE"
|
||||
deployment_maximum_percent = "${var.ecs_service_deployment_maximum_percent}"
|
||||
deployment_minimum_healthy_percent = "${var.ecs_service_deployment_minimum_healthy_percent}"
|
||||
|
||||
network_configuration {
|
||||
subnets = ["${values(local.private_subnets)}"]
|
||||
security_groups = ["${module.app.this_security_group_id}"]
|
||||
}
|
||||
|
||||
}
|
||||
```
|
||||
|
||||
当我必须定义允许访问所需端口的安全组时，我再次感到沮丧，当我这样做了并将其插入到网络配置中后，我就像被扇了一巴掌。
|
||||
|
||||
我还需要定义自己的负载均衡器？
|
||||
|
||||
什么？
|
||||
|
||||
当然不是吗？
|
||||
|
||||
##### 负载均衡器从未远离
|
||||
|
||||
老实说，我很满意，我甚至不确定为什么。我已经习惯了 Kubernetes 的服务和 Ingress 对象，我一心认为用 Kubernetes 将我的应用程序放到网上是多么容易。当然，我们在 $work 花了几个月的时间建立一个平台，以便更轻松。我是 [external-dns][8] 和 [cert-manager][9] 的重度用户，它们可以自动填充 Ingress 对象上的 DNS 条目并自动化 TLS 证书，我非常了解进行这些设置所需的工作，但老实说，我认为在 Fargate 上做这件事会更容易。我认识到 Fargate 并没有声称自己是“如何运行应用程序”这件事的全部和最终目的，它只是抽象出节点管理，但我一直被告知这比 Kubernetes *更加容易*。我真的很惊讶。定义负载均衡器（即使你不想使用 Ingress 和 Ingress Controller）也是向 Kubernetes 部署服务的重要组成部分，我不得不在这里再次做同样的事情。这一切都让人觉得如此熟悉。
|
||||
|
||||
我现在意识到我需要：
|
||||
|
||||
* 一个负载均衡器
|
||||
* 一个 TLS 证书
|
||||
* 一个 DNS 名字
|
||||
|
||||
所以我着手做了这些。我使用了一些流行的 terraform 模块，并做了这个：
|
||||
|
||||
```
|
||||
# Define a wildcard cert for my app
|
||||
module "acm" {
|
||||
source = "terraform-aws-modules/acm/aws"
|
||||
version = "v1.1.0"
|
||||
|
||||
create_certificate = true
|
||||
|
||||
domain_name = "${var.route53_zone_name}"
|
||||
zone_id = "${data.aws_route53_zone.this.id}"
|
||||
|
||||
subject_alternative_names = [
|
||||
"*.${var.route53_zone_name}",
|
||||
]
|
||||
|
||||
|
||||
tags = "${local.tags}"
|
||||
|
||||
}
|
||||
# Define my loadbalancer
|
||||
resource "aws_lb" "main" {
|
||||
name = "${var.name}"
|
||||
subnets = [ "${values(local.public_subnets)}" ]
|
||||
security_groups = ["${module.alb_https_sg.this_security_group_id}", "${module.alb_http_sg.this_security_group_id}"]
|
||||
}
|
||||
|
||||
resource "aws_lb_target_group" "main" {
|
||||
name = "${var.name}"
|
||||
port = "${var.app_port}"
|
||||
protocol = "HTTP"
|
||||
vpc_id = "${local.vpc_id}"
|
||||
target_type = "ip"
|
||||
depends_on = [ "aws_lb.main" ]
|
||||
}
|
||||
|
||||
# Redirect all traffic from the ALB to the target group
|
||||
resource "aws_lb_listener" "main" {
|
||||
load_balancer_arn = "${aws_lb.main.id}"
|
||||
port = "80"
|
||||
protocol = "HTTP"
|
||||
|
||||
default_action {
|
||||
target_group_arn = "${aws_lb_target_group.main.id}"
|
||||
type = "forward"
|
||||
}
|
||||
}
|
||||
|
||||
resource "aws_lb_listener" "main-tls" {
|
||||
load_balancer_arn = "${aws_lb.main.id}"
|
||||
port = "443"
|
||||
protocol = "HTTPS"
|
||||
certificate_arn = "${module.acm.this_acm_certificate_arn}"
|
||||
|
||||
default_action {
|
||||
target_group_arn = "${aws_lb_target_group.main.id}"
|
||||
type = "forward"
|
||||
}
|
||||
}
|
||||
```
|
||||
|
||||
我必须承认，我在这里搞砸了好几次。我不得不在 AWS 控制台中四处翻弄，以弄清楚我做错了什么。这当然不是一个“轻松”的过程，而且我之前已经做过很多次了。老实说，在这一点上，Kubernetes 看起来对我很有启发性，但我意识到这是因为我对它非常熟悉。幸运的是我能够使用托管的 Kubernetes 平台（预装了 external-dns 和 cert-manager），我真的很想知道我漏掉了 Fargate 什么增值的地方。它真的感觉不那么简单。
|
||||
|
||||
经过一番折腾，我现在有一个可以工作的 ECS 服务。包括服务在内的最终定义如下所示：
|
||||
|
||||
```
|
||||
data "aws_ecs_task_definition" "app" {
|
||||
task_definition = "${var.name}"
|
||||
depends_on = ["aws_ecs_task_definition.app"]
|
||||
}
|
||||
|
||||
resource "aws_ecs_service" "app" {
|
||||
name = "${var.name}"
|
||||
cluster = "${module.ecs.this_ecs_cluster_id}"
|
||||
task_definition = "${data.aws_ecs_task_definition.app.family}:${max(aws_ecs_task_definition.app.revision, data.aws_ecs_task_definition.app.revision)}"
|
||||
desired_count = "${var.ecs_service_desired_count}"
|
||||
launch_type = "FARGATE"
|
||||
deployment_maximum_percent = "${var.ecs_service_deployment_maximum_percent}"
|
||||
deployment_minimum_healthy_percent = "${var.ecs_service_deployment_minimum_healthy_percent}"
|
||||
|
||||
network_configuration {
|
||||
subnets = ["${values(local.private_subnets)}"]
|
||||
security_groups = ["${module.app_sg.this_security_group_id}"]
|
||||
}
|
||||
|
||||
load_balancer {
|
||||
target_group_arn = "${aws_lb_target_group.main.id}"
|
||||
container_name = "app"
|
||||
container_port = "${var.app_port}"
|
||||
}
|
||||
|
||||
depends_on = [
|
||||
"aws_lb_listener.main",
|
||||
]
|
||||
|
||||
}
|
||||
```
|
||||
|
||||
我觉得我已经接近完成了，但后来我记起了我只完成了最初的“入门”文档中所需的 3 个步骤中的 2 个，我仍然需要定义 ECS 群集。
|
||||
|
||||
#### 集群
|
||||
|
||||
感谢 [定义模块][10]，定义要所有这些运行的集群实际上非常简单。
|
||||
|
||||
```
|
||||
module "ecs" {
|
||||
source = "terraform-aws-modules/ecs/aws"
|
||||
version = "v1.1.0"
|
||||
|
||||
name = "${var.name}"
|
||||
}
|
||||
```
|
||||
|
||||
这里让我感到惊讶的是为什么我必须定义一个集群。作为一个相当熟悉 ECS 的人，你会觉得你需要一个集群，但我试图从一个必须经历这个过程的新人的角度来考虑这一点 —— 对我来说，Fargate 标榜自己“
|
||||
Serverless”而你仍需要定义集群，这似乎很令人惊讶。当然这是一个小细节，但它确实盘旋在我的脑海里。
|
||||
|
||||
### 告诉我你的 Secret
|
||||
|
||||
在这个阶段，我很高兴我成功地运行了一些东西。然而，我的原始的成功标准缺少一些东西。如果我们回到任务定义那里，你会记得我的应用程序有一个存放密码的环境变量：
|
||||
|
||||
```
|
||||
container_environment_variables = [
|
||||
{
|
||||
name = "USER"
|
||||
value = "${var.user}"
|
||||
},
|
||||
{
|
||||
name = "PASSWORD"
|
||||
value = "${var.password}"
|
||||
}
|
||||
]
|
||||
```
|
||||
|
||||
如果我在 AWS 控制台中查看我的任务定义，我的密码就在那里，明晃晃的明文。我希望不要这样，所以我开始尝试将其转化为其他东西，类似于 [Kubernetes 的Secrets管理][11]。
|
||||
|
||||
#### AWS SSM
|
||||
|
||||
Fargate / ECS 执行<ruby>secret 管理<rt>secret management</rt></ruby>部分的方式是使用 [AWS SSM][12]（此服务的全名是 AWS 系统管理器参数存储库 Systems Manager Parameter Store，但我不想使用这个名称，因为坦率地说这个名字太愚蠢了）。
|
||||
|
||||
AWS 文档很好的[涵盖了这个内容][13]，因此我开始将其转换为 terraform。
|
||||
|
||||
##### 指定秘密信息
|
||||
|
||||
首先，你必须定义一个参数并为其命名。在 terraform 中，它看起来像这样：
|
||||
|
||||
```
|
||||
resource "aws_ssm_parameter" "app_password" {
|
||||
name = "${var.app_password_param_name}" # The name of the value in AWS SSM
|
||||
type = "SecureString"
|
||||
value = "${var.app_password}" # The actual value of the password, like correct-horse-battery-stable
|
||||
}
|
||||
```
|
||||
|
||||
显然，这里的关键部分是 “SecureString” 类型。这会使用默认的 AWS KMS 密钥来加密数据，这对我来说并不是很直观。这比 Kubernetes 的 Secret 管理具有巨大优势，默认情况下，这些 Secret 在 etcd 中是不加密的。
|
||||
|
||||
然后我为 ECS 指定了另一个本地值映射，并将其作为 Secret 参数传递：
|
||||
|
||||
```
|
||||
container_secrets = [
|
||||
{
|
||||
name = "PASSWORD"
|
||||
valueFrom = "${var.app_password_param_name}"
|
||||
},
|
||||
]
|
||||
|
||||
module "container_definition_app" {
|
||||
source = "cloudposse/ecs-container-definition/aws"
|
||||
version = "v0.7.0"
|
||||
|
||||
container_name = "${var.name}"
|
||||
container_image = "${var.image}"
|
||||
|
||||
container_cpu = "${var.ecs_task_cpu}"
|
||||
container_memory = "${var.ecs_task_memory}"
|
||||
container_memory_reservation = "${var.container_memory_reservation}"
|
||||
|
||||
port_mappings = [
|
||||
{
|
||||
containerPort = "${var.app_port}"
|
||||
hostPort = "${var.app_port}"
|
||||
protocol = "tcp"
|
||||
},
|
||||
]
|
||||
|
||||
environment = "${local.container_environment_variables}"
|
||||
secrets = "${local.container_secrets}"
|
||||
```
|
||||
|
||||
##### 出了个问题
|
||||
|
||||
此刻，我重新部署了我的任务定义，并且非常困惑。为什么任务没有正确拉起？当新的任务定义（版本 8）可用时，我一直在控制台中看到正在运行的应用程序仍在使用先前的任务定义（版本 7）。解决这件事花费的时间比我预期的要长，但是在控制台的事件屏幕上，我注意到了 IAM 错误。我错过了一个步骤，容器无法从 AWS SSM 中读取 Secret 信息，因为它没有正确的 IAM 权限。这是我第一次真正对整个这件事情感到沮丧。从用户体验的角度来看，这里的反馈非常*糟糕*。如果我没有发觉的话，我会认为一切都很好，因为仍然有一个任务正在运行，我的应用程序仍然可以通过正确的 URL 访问 —— 只不过是旧的配置而已。
|
||||
|
||||
在 Kubernetes 里，我会清楚地看到 pod 定义中的错误。Fargate 可以确保我的应用不会停止，这绝对是太棒了，但作为一名运维，我需要一些关于发生了什么的实际反馈。这真的不够好。我真的希望 Fargate 团队的人能够读到这篇文章，改善这种体验。
|
||||
|
||||
### 就这样了
|
||||
|
||||
到这里就结束了，我的应用程序正在运行，也符合我的所有标准。我确实意识到我做了一些改进，其中包括：
|
||||
|
||||
* 定义一个 cloudwatch 日志组，这样我就可以正确地写日志了
|
||||
* 添加了一个 route53 托管区域，使整个事情从 DNS 角度更容易自动化
|
||||
* 修复并重新调整了 IAM 权限，这里太宽泛了
|
||||
|
||||
但老实说，现在我想反思一下这段经历。我写了一个关于我的经历的 [推特会话][14]，然后花了其余时间思考我在这里的真实感受。
|
||||
|
||||
### 代价
|
||||
|
||||
经过一夜的反思，我意识到无论你是使用 Fargate 还是 Kubernetes，这个过程都大致相同。最让我感到惊讶的是，尽管我经常听说 Fargate “更容易”，但我真的没有看到任何超过 Kubernetes 平台的好处。现在，如果你正在构建 Kubernetes 集群，我绝对可以看到这里的价值 —— 管理节点和控制面板只是不必要的开销，问题是 —— 基于 Kubernetes 的平台的大多数消费者都*没有*这样做。如果你很幸运能够使用 GKE，你几乎不需要考虑集群的管理，你可以使用单个 `gcloud` 命令来运行集群。我经常使用 Digital Ocean 的 Kubernetes 托管服务，我可以肯定地说它就像操作 Fargate 集群一样简单，实际上在某种程度上它更容易。
|
||||
|
||||
必须定义一些基础设施来运行你的容器就是此时的代价。谷歌本周可能刚刚使用他们的 [Google Cloud Run][15] 产品改变了游戏规则，但他们在这一领域的领先优势远远领先于其他所有人。
|
||||
|
||||
从这整个经历中，我可以肯定的说：*大规模运行容器仍然很难。*它需要思考，需要领域知识，需要运维和开发人员之间的协作。它还需要一个基础来构建 —— 任何基于 AWS 的操作都需要事先定义和运行一些基础架构。我对一些公司似乎渴望的 “NoOps” 概念非常感兴趣。我想如果你正在运行一个无状态应用程序，你可以把它全部放在一个 lambda 函数和一个 API 网关中，这可能不错，但我们是否真的适合在任何一种企业环境中这样做？我真的不这么认为。
|
||||
|
||||
#### 公平比较
|
||||
|
||||
令我印象深刻的另一个现实是，技术 A 和技术 B 之间的比较通常不太公平，我经常在 AWS 上看到这一点。这种实际情况往往与 Jeff Barr 博客文章截然不同。如果你是一家足够小的公司，你可以使用 AWS 控制台在 AWS 中部署你的应用程序并接受所有默认值，这绝对更容易。但是，我不想使用默认值，因为默认值几乎是不适用于生产环境的。一旦你开始剥离掉云服务商服务的层面，你就会开始意识到最终你仍然是在运行软件 —— 它仍然需要设计良好、部署良好、运行良好。我相信 AWS 和 Kubernetes 以及所有其他云服务商的增值服务使得它更容易运行、设计和操作，但它绝对不是免费的。
|
||||
|
||||
#### Kubernetes 的争议
|
||||
|
||||
最后就是：如果你将 Kubernetes 纯粹视为一个容器编排工具，你可能会喜欢 Fargate。然而，随着我对 Kubernetes 越来越熟悉，我开始意识到它作为一种技术的重要性 —— 不仅因为它是一个伟大的容器编排工具，而且因为它的设计模式 —— 它是声明性的、API 驱动的平台。 在*整个* Fargate 过程期间发生的一个简单的事情是，如果我删除这里某个东西，Fargate 不一定会为我重新创建它。自动缩放很不错，不需要管理服务器和操作系统的补丁及更新也很棒，但我觉得因为无法使用 Kubernetes 自我修复和 API 驱动模型而失去了很多。当然，Kubernetes 有一个学习曲线，但从这里的体验来看，Fargate 也是如此。
|
||||
|
||||
### 总结
|
||||
|
||||
尽管我在这个过程中遭遇了困惑，但我确实很喜欢这种体验。我仍然相信 Fargate 是一项出色的技术，AWS 团队对 ECS/Fargate 所做的工作确实非常出色。然而，我的观点是，这绝对不比 Kubernetes “更容易”，只是……难点不同。
|
||||
|
||||
在生产环境中运行容器时出现的问题大致相同。如果你从这篇文章中有所收获，它应该是这样的：*不管你选择的哪种方式都有运维开销*。不要相信你选择一些东西你的世界就变得更轻松。我个人的意见是：如果你有一个运维团队，而你的公司要为多个应用程序团队部署容器 —— 选择一种技术并围绕它构建流程和工具以使其更容易。
|
||||
|
||||
人们说的一点肯定没错，用点技巧可以更容易地使用某种技术。在这个阶段，谈到 Fargate，下面的漫画这总结了我的感受：
|
||||
|
||||
![][16]
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://leebriggs.co.uk/blog/2019/04/13/the-fargate-illusion.html
|
||||
|
||||
作者：[Lee Briggs][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[Bestony](https://github.com/Bestony)
|
||||
校对：[wxy](https://github.com/wxy), 临石（阿里云智能技术专家）
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://leebriggs.co.uk/
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://matthias-endler.de/2019/maybe-you-dont-need-kubernetes/
|
||||
[2]: https://aws.amazon.com/fargate/
|
||||
[3]: https://docs.aws.amazon.com/AmazonECS/latest/developerguide/ECS_GetStarted.html
|
||||
[4]: https://i.imgur.com/YfMyXBdl.png
|
||||
[5]: https://docs.aws.amazon.com/AmazonECS/latest/developerguide/task_definition_parameters.html
|
||||
[6]: https://github.com/cloudposse/terraform-aws-ecs-container-definition
|
||||
[7]: https://leebriggs.co.uk/blog/2018/05/08/kubernetes-config-mgmt.html
|
||||
[8]: https://github.com/kubernetes-incubator/external-dns
|
||||
[9]: https://github.com/jetstack/cert-manager
|
||||
[10]: https://github.com/terraform-aws-modules/terraform-aws-ecs
|
||||
[11]: https://kubernetes.io/docs/concepts/configuration/secret/
|
||||
[12]: https://docs.aws.amazon.com/systems-manager/latest/userguide/systems-manager-paramstore.html
|
||||
[13]: https://docs.aws.amazon.com/AmazonECS/latest/developerguide/specifying-sensitive-data.html
|
||||
[14]: https://twitter.com/briggsl/status/1116870900719030272
|
||||
[15]: https://cloud.google.com/run/
|
||||
[16]: https://i.imgur.com/Bx7Q50Jl.jpg
|
||||
@@ -1,46 +0,0 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (Which programming languages should you learn?)
|
||||
[#]: via: (https://opensource.com/article/19/2/which-programming-languages-should-you-learn)
|
||||
[#]: author: (Marty Kalin https://opensource.com/users/mkalindepauledu)
|
||||
|
||||
Which programming languages should you learn?
|
||||
======
|
||||
Learning a new programming language is a great way to get ahead in your career. But which one?
|
||||
|
||||
|
||||
If you want to get started or get ahead in your programming career, learning a new language is a smart idea. But the huge number of languages in active use invites the question: Which programming language is the best one to know? To answer that, let's start with a simplifying question: What sort of programming do you want to do?
|
||||
|
||||
If you want to do web programming on the client side, then the specialized languages HTML, CSS, and JavaScript—in one of its seemingly infinite dialects—are de rigueur.
|
||||
|
||||
If you want to do web programming on the server side, the options include all of the familiar general-purpose languages: C++, Golang, Java, C#, Node.js, Perl, Python, Ruby, and so on. As a matter of course, server-side programs interact with datastores, such as relational and other databases, which means query languages such as SQL may come into play.
|
||||
|
||||
If you're writing native apps for mobile devices, knowing the target platform is important. For Apple devices, Swift has supplanted Objective C as the language of choice. For Android devices, Java (with dedicated libraries and toolsets) remains the dominant language. There are special languages such as Xamarin, used with C#, that can generate platform-specific code for Apple, Android, and Windows devices.
|
||||
|
||||
What about general-purpose languages? There are various choices within the usual pigeonholes. Among the dynamic or scripting languages (e.g., Perl, Python, and Ruby), there are newer offerings such as Node.js. Java and C#, which are more alike than their fans like to admit, remain the dominant statically compiled languages targeted at a virtual machine (the JVM and CLR, respectively). Among languages that compile into native executables, C++ is still in the mix, along with later arrivals such as Golang and Rust. General-purpose functional languages abound (e.g., Clojure, Haskell, Erlang, F#, Lisp, and Scala), often with passionately devoted communities. It's worth noting that object-oriented languages such as Java and C# have added functional constructs (in particular, lambdas), and the dynamic languages have had functional constructs from the start.
|
||||
|
||||
Let me end with a pitch for C, which is a small, elegant, and extensible language not to be confused with C++. Modern operating systems are written mostly in C, with the rest in assembly language. The standard libraries on any platform are likewise mostly in C. For example, any program that issues the Hello, world! greeting does so through a call to the C library function named **write**.
|
||||
|
||||
C serves as a portable assembly language, exposing details about the underlying system that other high-level languages deliberately hide. To understand C is thus to gain a better grasp of how programs contend for the shared system resources (processors, memory, and I/O devices) required for execution. C is at once high-level and close-to-the-metal, so unrivaled in performance—except, of course, for assembly language. Finally, C is the lingua franca among programming languages, and almost every general-purpose language supports C calls in one form or another.
|
||||
|
||||
For a modern introduction to C, consider my book [C Programming: Introducing Portable Assembler][1]. No matter how you go about it, learn C and you'll learn a lot more than just another programming language.
|
||||
|
||||
What programming languages do you think are important to know? Do you agree or disagree with these recommendations? Let us know in the comments!
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/19/2/which-programming-languages-should-you-learn
|
||||
|
||||
作者：[Marty Kalin][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://opensource.com/users/mkalindepauledu
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://www.amazon.com/dp/1977056954?ref_=pe_870760_150889320
|
||||
@@ -1,130 +0,0 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: (zgj1024 )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (Why DevOps is the most important tech strategy today)
|
||||
[#]: via: (https://opensource.com/article/19/3/devops-most-important-tech-strategy)
|
||||
[#]: author: (Kelly AlbrechtWilly-Peter Schaub https://opensource.com/users/ksalbrecht/users/brentaaronreed/users/wpschaub/users/wpschaub/users/ksalbrecht)
|
||||
|
||||
Why DevOps is the most important tech strategy today
|
||||
======
|
||||
Clearing up some of the confusion about DevOps.
|
||||
![CICD with gears][1]
|
||||
|
||||
Many people first learn about [DevOps][2] when they see one of its outcomes and ask how it happened. It's not necessary to understand why something is part of DevOps to implement it, but knowing that—and why a DevOps strategy is important—can mean the difference between being a leader or a follower in an industry.
|
||||
|
||||
Maybe you've heard some the incredible outcomes attributed to DevOps, such as production environments that are so resilient they can handle thousands of releases per day while a "[Chaos Monkey][3]" is running around randomly unplugging things. This is impressive, but on its own, it's a weak business case, essentially burdened with [proving a negative][4]: The DevOps environment is resilient because a serious failure hasn't been observed… yet.
|
||||
|
||||
There is a lot of confusion about DevOps and many people are still trying to make sense of it. Here's an example from someone in my LinkedIn feed:
|
||||
|
||||
> Recently attended few #DevOps sessions where some speakers seemed to suggest #Agile is a subset of DevOps. Somehow, my understanding was just the opposite.
|
||||
>
|
||||
> Would like to hear your thoughts. What do you think is the relationship between Agile and DevOps?
|
||||
>
|
||||
> 1. DevOps is a subset of Agile
|
||||
> 2. Agile is a subset of DevOps
|
||||
> 3. DevOps is an extension of Agile, starts where Agile ends
|
||||
> 4. DevOps is the new version of Agile
|
||||
>
|
||||
|
||||
|
||||
Tech industry professionals have been weighing in on the LinkedIn post with a wide range of answers. How would you respond?
|
||||
|
||||
### DevOps' roots in lean and agile
|
||||
|
||||
DevOps makes a lot more sense if we start with the strategies of Henry Ford and the Toyota Production System's refinements of Ford's model. Within this history is the birthplace of lean manufacturing, which has been well studied. In [_Lean Thinking_][5], James P. Womack and Daniel T. Jones distill it into five principles:
|
||||
|
||||
1. Specify the value desired by the customer
|
||||
2. Identify the value stream for each product providing that value and challenge all of the wasted steps currently necessary to provide it
|
||||
3. Make the product flow continuously through the remaining value-added steps
|
||||
4. Introduce pull between all steps where continuous flow is possible
|
||||
5. Manage toward perfection so that the number of steps and the amount of time and information needed to serve the customer continually falls
|
||||
|
||||
|
||||
|
||||
Lean seeks to continuously remove waste and increase the flow of value to the customer. This is easily recognizable and understood through a core tenet of lean: single piece flow. We can do a number of activities to learn why moving single pieces at a time is magnitudes faster than batches of many pieces; the [Penny Game][6] and the [Airplane Game][7] are two of them. In the Penny Game, if a batch of 20 pennies takes two minutes to get to the customer, they get the whole batch after waiting two minutes. If you move one penny at a time, the customer gets the first penny in about five seconds and continues getting pennies until the 20th penny arrives approximately 25 seconds later.
|
||||
|
||||
This is a huge difference, but not everything in life is as simple and predictable as the penny in the Penny Game. This is where agile comes in. We certainly see lean principles on high-performing agile teams, but these teams need more than lean to do what they do.
|
||||
|
||||
To be able to handle the unpredictability and variance of typical software development tasks, agile methodology focuses on awareness, deliberation, decision, and action to adjust course in the face of a constantly changing reality. For example, agile frameworks (like scrum) increase awareness with ceremonies like the daily standup and the sprint review. If the scrum team becomes aware of a new reality, the framework allows and encourages them to adjust course if necessary.
|
||||
|
||||
For teams to make these types of decisions, they need to be self-organizing in a high-trust environment. High-performing agile teams working this way achieve a fast flow of value while continuously adjusting course, removing the waste of going in the wrong direction.
|
||||
|
||||
### Optimal batch size
|
||||
|
||||
To understand the power of DevOps in software development, it helps to understand the economics of batch size. Consider the following U-curve optimization illustration from Donald Reinertsen's _[Principles of Product Development Flow][8]:_
|
||||
|
||||
![U-curve optimization illustration of optimal batch size][9]
|
||||
|
||||
This can be explained with an analogy about grocery shopping. Suppose you need to buy some eggs and you live 30 minutes from the store. Buying one egg (far left on the illustration) at a time would mean a 30-minute trip each time. This is your _transaction cost_. The _holding cost_ might represent the eggs spoiling and taking up space in your refrigerator over time. The _total cost_ is the _transaction cost_ plus your _holding cost_. This U-curve explains why, for most people, buying a dozen eggs at a time is their _optimal batch size_. If you lived next door to the store, it'd cost you next to nothing to walk there, and you'd probably buy a smaller carton each time to save room in your refrigerator and enjoy fresher eggs.
|
||||
|
||||
This U-curve optimization illustration can shed some light on why productivity increases significantly in successful agile transformations. Consider the effect of agile transformation on decision making in an organization. In traditional hierarchical organizations, decision-making authority is centralized. This leads to larger decisions made less frequently by fewer people. An agile methodology will effectively reduce an organization's transaction cost for making decisions by decentralizing the decisions to where the awareness and information is the best known: across the high-trust, self-organizing agile teams.
|
||||
|
||||
The following animation shows how reducing transaction cost shifts the optimal batch size to the left. You can't understate the value to an organization in making faster decisions more frequently.
|
||||
|
||||
![U-curve optimization illustration][10]
|
||||
|
||||
### Where does DevOps fit in?
|
||||
|
||||
Automation is one of the things DevOps is most known for. The previous illustration shows the value of automation in great detail. Through automation, we reduce our transaction costs to nearly zero, essentially getting our testing and deployments for free. This lets us take advantage of smaller and smaller batch sizes of work. Smaller batches of work are easier to understand, commit to, test, review, and know when they are done. These smaller batch sizes also contain less variance and risk, making them easier to deploy and, if something goes wrong, to troubleshoot and recover from. With automation combined with a solid agile practice, we can get our feature development very close to single piece flow, providing value to customers quickly and continuously.
|
||||
|
||||
More traditionally, DevOps is understood as a way to knock down the walls of confusion between the dev and ops teams. In this model, development teams develop new features, while operations teams keep the system stable and running smoothly. Friction occurs because new features from development introduce change into the system, increasing the risk of an outage, which the operations team doesn't feel responsible for—but has to deal with anyway. DevOps is not just trying to get people working together, it's more about trying to make more frequent changes safely in a complex environment.
|
||||
|
||||
We can look to [Ron Westrum][11] for research about achieving safety in complex organizations. In researching why some organizations are safer than others, he found that an organization's culture is predictive of its safety. He identified three types of culture: Pathological, Bureaucratic, and Generative. He found that the Pathological culture was predictive of less safety and the Generative culture was predictive of more safety (e.g., far fewer plane crashes or accidental hospital deaths in his main areas of research).
|
||||
|
||||
![Three types of culture identified by Ron Westrum][12]
|
||||
|
||||
Effective DevOps teams achieve a Generative culture with lean and agile practices, showing that speed and safety are complementary, or two sides of the same coin. By reducing the optimal batch sizes of decisions and features to become very small, DevOps achieves a faster flow of information and value while removing waste and reducing risk.
|
||||
|
||||
In line with Westrum's research, change can happen easily with safety and reliability improving at the same time. When an agile DevOps team is trusted to make its own decisions, we get the tools and techniques DevOps is most known for today: automation and continuous delivery. Through this automation, transaction costs are reduced further than ever, and a near single piece lean flow is achieved, creating the potential for thousands of decisions and releases per day, as we've seen happen in high-performing DevOps organizations.
|
||||
|
||||
### Flow, feedback, learning
|
||||
|
||||
DevOps doesn't stop there. We've mainly been talking about DevOps achieving a revolutionary flow, but lean and agile practices are further amplified through similar efforts that achieve faster feedback loops and faster learning. In the [_DevOps Handbook_][13], the authors explain in detail how, beyond its fast flow, DevOps achieves telemetry across its entire value stream for fast and continuous feedback. Further, leveraging the [kaizen][14] bursts of lean and the [retrospectives][15] of scrum, high-performing DevOps teams will continuously drive learning and continuous improvement deep into the foundations of their organizations, achieving a lean manufacturing revolution in the software product development industry.
|
||||
|
||||
### Start with a DevOps assessment
|
||||
|
||||
The first step in leveraging DevOps is, either after much study or with the help of a DevOps consultant and coach, to conduct an assessment across a suite of dimensions consistently found in high-performing DevOps teams. The assessment should identify weak or non-existent team norms that need improvement. Evaluate the assessment's results to find quick wins—focus areas with high chances for success that will produce high-impact improvement. Quick wins are important for gaining the momentum needed to tackle more challenging areas. The teams should generate ideas that can be tried quickly and start to move the needle on the DevOps transformation.
|
||||
|
||||
After some time, the team should reassess on the same dimensions to measure improvements and identify new high-impact focus areas, again with fresh ideas from the team. A good coach will consult, train, mentor, and support as needed until the team owns its own continuous improvement and achieves near consistency on all dimensions by continually reassessing, experimenting, and learning.
|
||||
|
||||
In the [second part][16] of this article, we'll look at results from a DevOps survey in the Drupal community and see where the quick wins are most likely to be found.
|
||||
|
||||
* * *
|
||||
|
||||
_Rob_ _Bayliss and Kelly Albrecht will present[DevOps: Why, How, and What][17] and host a follow-up [Birds of a][18]_ [_Feather_][18] _[discussion][18] at [DrupalCon 2019][19] in Seattle, April 8-12._
|
||||
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/19/3/devops-most-important-tech-strategy
|
||||
|
||||
作者：[Kelly AlbrechtWilly-Peter Schaub][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://opensource.com/users/ksalbrecht/users/brentaaronreed/users/wpschaub/users/wpschaub/users/ksalbrecht
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/cicd_continuous_delivery_deployment_gears.png?itok=kVlhiEkc (CICD with gears)
|
||||
[2]: https://opensource.com/resources/devops
|
||||
[3]: https://github.com/Netflix/chaosmonkey
|
||||
[4]: https://en.wikipedia.org/wiki/Burden_of_proof_(philosophy)#Proving_a_negative
|
||||
[5]: https://www.amazon.com/dp/B0048WQDIO/ref=dp-kindle-redirect?_encoding=UTF8&btkr=1
|
||||
[6]: https://youtu.be/5t6GhcvKB8o?t=54
|
||||
[7]: https://www.shmula.com/paper-airplane-game-pull-systems-push-systems/8280/
|
||||
[8]: https://www.amazon.com/dp/B00K7OWG7O/ref=dp-kindle-redirect?_encoding=UTF8&btkr=1
|
||||
[9]: https://opensource.com/sites/default/files/uploads/batch_size_optimal_650.gif (U-curve optimization illustration of optimal batch size)
|
||||
[10]: https://opensource.com/sites/default/files/uploads/batch_size_650.gif (U-curve optimization illustration)
|
||||
[11]: https://en.wikipedia.org/wiki/Ron_Westrum
|
||||
[12]: https://opensource.com/sites/default/files/uploads/information_flow.png (Three types of culture identified by Ron Westrum)
|
||||
[13]: https://www.amazon.com/DevOps-Handbook-World-Class-Reliability-Organizations/dp/1942788002/ref=sr_1_3?keywords=DevOps+handbook&qid=1553197361&s=books&sr=1-3
|
||||
[14]: https://en.wikipedia.org/wiki/Kaizen
|
||||
[15]: https://www.scrum.org/resources/what-is-a-sprint-retrospective
|
||||
[16]: https://opensource.com/article/19/3/where-drupal-community-stands-devops-adoption
|
||||
[17]: https://events.drupal.org/seattle2019/sessions/devops-why-how-and-what
|
||||
[18]: https://events.drupal.org/seattle2019/bofs/devops-getting-started
|
||||
[19]: https://events.drupal.org/seattle2019
|
||||
@@ -0,0 +1,69 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (Anti-lasers could give us perfect antennas, greater data capacity)
|
||||
[#]: via: (https://www.networkworld.com/article/3386879/anti-lasers-could-give-us-perfect-antennas-greater-data-capacity.html#tk.rss_all)
|
||||
[#]: author: (Patrick Nelson https://www.networkworld.com/author/Patrick-Nelson/)
|
||||
|
||||
Anti-lasers could give us perfect antennas, greater data capacity
|
||||
======
|
||||
Anti-lasers get close to providing a 100% efficient signal channel for data, say engineers.
|
||||
![Guirong Hao / Valery Brozhinsky / Getty Images][1]
|
||||
|
||||
Playing laser light backwards could adjust data transmission signals so that they perfectly match receiving antennas. The fine-tuning of signals like this, not achieved with such detail before, could create more capacity for ever-increasing data demand.
|
||||
|
||||
"Imagine, for example, that you could adjust a cell phone signal exactly the right way, so that it is perfectly absorbed by the antenna in your phone," says Stefan Rotter of the Institute for Theoretical Physics of Technische Universität Wien (TU Wien) in a [press release][2].
|
||||
|
||||
Rotter is talking about “Random Anti-Laser,” a project he has been a part of. The idea behind it is that if one could time-reverse a laser, then the laser (right now considered the best light source ever built) becomes the best available light absorber. Perfect absorption of a signal wave would mean that all of the data-carrying energy is absorbed by the receiving device, thus it becomes 100% efficient.
|
||||
|
||||
**[ Related:[What is 5G wireless? How it will change networking as we know it?][3] ]**
|
||||
|
||||
“The easiest way to think about this process is in terms of a movie showing a conventional laser sending out laser light, which is played backwards,” the TU Wein article says. The anti-laser is the exact opposite of the laser — instead of sending specific colors perfectly when energy is applied, it receives specific colors perfectly.
|
||||
|
||||
Perfect absorption of a signal wave would mean that all of the data-carrying energy is absorbed by the receiving device, thus it becomes 100% efficient.
|
||||
|
||||
Counter-intuitively, it’s the random scattering of light in all directions that’s behind the engineering. However, the Vienna, Austria, university group performs precise calculations on those scattering, splitting signals. That lets the researchers harness the light.
|
||||
|
||||
### How the anti-laser technology works
|
||||
|
||||
The microwave-based, experimental device the researchers have built in the lab to prove the idea doesn’t just potentially apply to cell phones; wireless internet of things (IoT) devices would also get more data throughput. How it works: The device consists of an antenna-containing chamber encompassed by cylinders, all arranged haphazardly, the researchers explain. The cylinders distribute an elaborate, arbitrary wave pattern “similar to [throwing] stones in a puddle of water, at which water waves are deflected.”
|
||||
|
||||
Measurements then take place to identify exactly how the signals return. The team involved, which also includes collaborators from the University of Nice, France, then “characterize the random structure and calculate the wave front that is completely swallowed by the central antenna at the right absorption strength.” Ninety-nine point eight percent is absorbed, making it remarkably and virtually perfect. Data throughput, range, and other variables thus improve.
|
||||
|
||||
**[[Take this mobile device management course from PluralSight and learn how to secure devices in your company without degrading the user experience.][4] ]**
|
||||
|
||||
Achieving perfect antennas has been pretty much only theoretically possible for engineers to date. Reflected energy (RF back into the transmitter from antenna inefficiencies) has always been an issue in general. Reflections from surfaces, too, have been always been a problem.
|
||||
|
||||
“Think about a mobile phone signal that is reflected several times before it reaches your cell phone,” Rotter says. It’s not easy to get the tuning right — as the antennas’ physical locations move, reflected surfaces become different.
|
||||
|
||||
### Scattering lasers
|
||||
|
||||
Scattering, similar to that used in this project, is becoming more important in communications overall. “Waves that are being scattered in a complex way are really all around us,” the group says.
|
||||
|
||||
An example is random-lasers (which the group’s anti-laser is based on) that unlike traditional lasers, do not use reflective surfaces but trap scattered light and then “emit a very complicated, system-specific laser field when supplied with energy.” The anti-random-laser developed by Rotter and his group simply reverses that in time:
|
||||
|
||||
“Instead of a light source that emits a specific wave depending on its random inner structure, it is also possible to build the perfect absorber.” The anti-random-laser.
|
||||
|
||||
Join the Network World communities on [Facebook][5] and [LinkedIn][6] to comment on topics that are top of mind.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.networkworld.com/article/3386879/anti-lasers-could-give-us-perfect-antennas-greater-data-capacity.html#tk.rss_all
|
||||
|
||||
作者：[Patrick Nelson][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://www.networkworld.com/author/Patrick-Nelson/
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://images.idgesg.net/images/article/2019/03/data_cubes_transformation_conversion_by_guirong_hao_gettyimages-1062387214_plus_abstract_binary_by_valerybrozhinsky_gettyimages-865457032_3x2_2400x1600-100790211-large.jpg
|
||||
[2]: https://www.tuwien.ac.at/en/news/news_detail/article/126574/
|
||||
[3]: https://www.networkworld.com/article/3203489/lan-wan/what-is-5g-wireless-networking-benefits-standards-availability-versus-lte.html
|
||||
[4]: https://pluralsight.pxf.io/c/321564/424552/7490?u=https%3A%2F%2Fwww.pluralsight.com%2Fcourses%2Fmobile-device-management-big-picture
|
||||
[5]: https://www.facebook.com/NetworkWorld/
|
||||
[6]: https://www.linkedin.com/company/network-world
|
||||
@@ -0,0 +1,60 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (Google partners with Intel, HPE and Lenovo for hybrid cloud)
|
||||
[#]: via: (https://www.networkworld.com/article/3388062/google-partners-with-intel-hpe-and-lenovo-for-hybrid-cloud.html#tk.rss_all)
|
||||
[#]: author: (Andy Patrizio https://www.networkworld.com/author/Andy-Patrizio/)
|
||||
|
||||
Google partners with Intel, HPE and Lenovo for hybrid cloud
|
||||
======
|
||||
Google boosted its on-premises and cloud connections with Kubernetes and serverless computing.
|
||||
![Ilze Lucero \(CC0\)][1]
|
||||
|
||||
Still struggling to get its Google Cloud business out of single-digit marketshare, Google this week introduced new partnerships with Lenovo and Intel to help bolster its hybrid cloud offerings, both built on Google’s Kubernetes container technology.
|
||||
|
||||
At Google’s Next ’19 show this week, Intel and Google said they will collaborate on Google's Anthos, a new reference design based on the second-Generation Xeon Scalable processor introduced last week and an optimized Kubernetes software stack designed to deliver increased workload portability between public and private cloud environments.
|
||||
|
||||
**[ Read also:[What hybrid cloud means in practice][2] | Get regularly scheduled insights: [Sign up for Network World newsletters][3] ]**
|
||||
|
||||
As part the Anthos announcement, Hewlett Packard Enterprise (HPE) said it has validated Anthos on its ProLiant servers, while Lenovo has done the same for its ThinkAgile platform. This solution will enable customers to get a consistent Kubernetes experience between Google Cloud and their on-premises HPE or Lenovo servers. No official word from Dell yet, but they can’t be far behind.
|
||||
|
||||
Users will be able to manage their Kubernetes clusters and enforce policy consistently across environments – either in the public cloud or on-premises. In addition, Anthos delivers a fully integrated stack of hardened components, including OS and container runtimes that are tested and validated by Google, so customers can upgrade their clusters with confidence and minimize downtime.
|
||||
|
||||
### What is Google Anthos?
|
||||
|
||||
Google formally introduced [Anthos][4] at this year’s show. Anthos, formerly Cloud Services Platform, is meant to allow users to run their containerized applications without spending time on building, managing, and operating Kubernetes clusters. It runs both on Google Cloud Platform (GCP) with Google Kubernetes Engine (GKE) and in your data center with GKE On-Prem. Anthos will also let you manage workloads running on third-party clouds such as Amazon Web Services (AWS) and Microsoft Azure.
|
||||
|
||||
Google also announced the beta release of Anthos Migrate, which auto-migrates virtual machines (VM) from on-premises or other clouds directly into containers in GKE with minimal effort. This allows enterprises to migrate their infrastructure in one streamlined motion, without upfront modifications to the original VMs or applications.
|
||||
|
||||
Intel said it will publish the production design as an Intel Select Solution, as well as a developer platform, making it available to anyone who wants it.
|
||||
|
||||
### Serverless environments
|
||||
|
||||
Google isn’t stopping with Kubernetes containers, it’s also pushing ahead with serverless environments. [Cloud Run][5] is Google’s implementation of serverless computing, which is something of a misnomer. You still run your apps on servers; you just aren’t using a dedicated physical server. It is stateless, so resources are not allocated until you actually run or use the application.
|
||||
|
||||
Cloud Run is a fully serverless offering that takes care of all infrastructure management, including the provisioning, configuring, scaling, and managing of servers. It automatically scales up or down within seconds, even down to zero depending on traffic, ensuring you pay only for the resources you actually use. Cloud Run can be used on GKE, offering the option to run side by side with other workloads deployed in the same cluster.
|
||||
|
||||
Join the Network World communities on [Facebook][6] and [LinkedIn][7] to comment on topics that are top of mind.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.networkworld.com/article/3388062/google-partners-with-intel-hpe-and-lenovo-for-hybrid-cloud.html#tk.rss_all
|
||||
|
||||
作者：[Andy Patrizio][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://www.networkworld.com/author/Andy-Patrizio/
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://images.idgesg.net/images/article/2018/03/cubes_blocks_squares_containers_ilze_lucero_cc0_via_unsplash_1200x800-100752172-large.jpg
|
||||
[2]: https://www.networkworld.com/article/3249495/what-hybrid-cloud-mean-practice
|
||||
[3]: https://www.networkworld.com/newsletters/signup.html
|
||||
[4]: https://cloud.google.com/blog/topics/hybrid-cloud/new-platform-for-managing-applications-in-todays-multi-cloud-world
|
||||
[5]: https://cloud.google.com/blog/products/serverless/announcing-cloud-run-the-newest-member-of-our-serverless-compute-stack
|
||||
[6]: https://www.facebook.com/NetworkWorld/
|
||||
[7]: https://www.linkedin.com/company/network-world
|
||||
@@ -0,0 +1,60 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (HPE and Nutanix partner for hyperconverged private cloud systems)
|
||||
[#]: via: (https://www.networkworld.com/article/3388297/hpe-and-nutanix-partner-for-hyperconverged-private-cloud-systems.html#tk.rss_all)
|
||||
[#]: author: (Andy Patrizio https://www.networkworld.com/author/Andy-Patrizio/)
|
||||
|
||||
HPE and Nutanix partner for hyperconverged private cloud systems
|
||||
======
|
||||
Both companies will sell HP ProLiant appliances with Nutanix software but to different markets.
|
||||
![Hewlett Packard Enterprise][1]
|
||||
|
||||
Hewlett Packard Enterprise (HPE) has partnered with Nutanix to offer Nutanix’s hyperconverged infrastructure (HCI) software available as a managed private cloud service and on HPE-branded appliances.
|
||||
|
||||
As part of the deal, the two companies will be competing against each other in hardware sales, sort of. If you want the consumption model you get through HPE’s GreenLake, where your usage is metered and you pay for only the time you use it (similar to the cloud), then you would get the ProLiant hardware from HPE.
|
||||
|
||||
If you want an appliance model where you buy the hardware outright, like in the traditional sense of server sales, you would get the same ProLiant through Nutanix.
|
||||
|
||||
**[ Read also:[What is hybrid cloud computing?][2] and [Multicloud mania: what to know][3] ]**
|
||||
|
||||
As it is, HPE GreenLake offers multiple cloud offerings to customers, including virtualization courtesy of VMware and Microsoft. With the Nutanix partnership, HPE is adding Nutanix’s free Acropolis hypervisor to its offerings.
|
||||
|
||||
“Customers get to choose an alternative to VMware with this,” said Pradeep Kumar, senior vice president and general manager of HPE’s Pointnext consultancy. “They like the Acropolis license model, since it’s license-free. Then they have choice points so pricing is competitive. Some like VMware, and I think it’s our job to offer them both and they can pick and choose.”
|
||||
|
||||
Kumar added that the whole Nutanix stack is 15 to 18% less with Acropolis than a VMware-powered system, since they save on the hypervisor.
|
||||
|
||||
The HPE-Nutanix partnership offers a fully managed hybrid cloud infrastructure delivered as a service and deployed in customers’ data centers or co-location facility. The managed private cloud service gives enterprises a hyperconverged environment in-house without having to manage the infrastructure themselves and, more importantly, without the burden of ownership. GreenLake operates more like a lease than ownership.
|
||||
|
||||
### HPE GreenLake's private cloud services promise to significantly reduce costs
|
||||
|
||||
HPE is pushing hard on GreenLake, which basically mimics cloud platform pricing models of paying for what you use rather than outright ownership. Kumar said HPE projects the consumption model will account for 30% of HPE’s business in the next few years.
|
||||
|
||||
GreenLake makes some hefty promises. According to Nutanix-commissioned IDC research, customers will achieve a 60% reduction in the five-year cost of operations, while a HPE-commissioned Forrester report found customers benefit from a 30% Capex savings due to eliminated need for overprovisioning and a 90% reduction in support and professional services costs.
|
||||
|
||||
By shifting to an IT as a Service model, HPE claims to provide a 40% increase in productivity by reducing the support load on IT operations staff and to shorten the time to deploy IT projects by 65%.
|
||||
|
||||
The two new offerings from the partnership – HPE GreenLake’s private cloud service running Nutanix software and the HPE-branded appliances integrated with Nutanix software – are expected to be available during the 2019 third quarter, the companies said.
|
||||
|
||||
Join the Network World communities on [Facebook][4] and [LinkedIn][5] to comment on topics that are top of mind.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.networkworld.com/article/3388297/hpe-and-nutanix-partner-for-hyperconverged-private-cloud-systems.html#tk.rss_all
|
||||
|
||||
作者：[Andy Patrizio][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://www.networkworld.com/author/Andy-Patrizio/
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://images.techhive.com/images/article/2015/11/hpe_building-100625424-large.jpg
|
||||
[2]: https://www.networkworld.com/article/3233132/cloud-computing/what-is-hybrid-cloud-computing.html
|
||||
[3]: https://www.networkworld.com/article/3252775/hybrid-cloud/multicloud-mania-what-to-know.html
|
||||
[4]: https://www.facebook.com/NetworkWorld/
|
||||
[5]: https://www.linkedin.com/company/network-world
|
||||
@@ -0,0 +1,76 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (Gov’t warns on VPN security bug in Cisco, Palo Alto, F5, Pulse software)
|
||||
[#]: via: (https://www.networkworld.com/article/3388646/gov-t-warns-on-vpn-security-bug-in-cisco-palo-alto-f5-pulse-software.html#tk.rss_all)
|
||||
[#]: author: (Michael Cooney https://www.networkworld.com/author/Michael-Cooney/)
|
||||
|
||||
Gov’t warns on VPN security bug in Cisco, Palo Alto, F5, Pulse software
|
||||
======
|
||||
VPN packages from Cisco, Palo Alto, F5 and Pusle may improperly secure tokens and cookies
|
||||
![Getty Images][1]
|
||||
|
||||
The Department of Homeland Security has issued a warning that some [VPN][2] packages from Cisco, Palo Alto, F5 and Pusle may improperly secure tokens and cookies, allowing nefarious actors an opening to invade and take control over an end user’s system.
|
||||
|
||||
The DHS’s Cybersecurity and Infrastructure Security Agency (CISA) [warning][3] comes on the heels of a notice from Carnegie Mellon's CERT that multiple VPN applications store the authentication and/or session cookies insecurely in memory and/or log files.
|
||||
|
||||
**[Also see:[What to consider when deploying a next generation firewall][4]. Get regularly scheduled insights by [signing up for Network World newsletters][5]]**
|
||||
|
||||
“If an attacker has persistent access to a VPN user's endpoint or exfiltrates the cookie using other methods, they can replay the session and bypass other authentication methods,” [CERT wrote][6]. “An attacker would then have access to the same applications that the user does through their VPN session.”
|
||||
|
||||
According to the CERT warning, the following products and versions store the cookie insecurely in log files:
|
||||
|
||||
* Palo Alto Networks GlobalProtect Agent 4.1.0 for Windows and GlobalProtect Agent 4.1.10 and earlier for macOS0 ([CVE-2019-1573][7])
|
||||
* Pulse Secure Connect Secure prior to 8.1R14, 8.2, 8.3R6, and 9.0R2.
|
||||
|
||||
|
||||
|
||||
The following products and versions store the cookie insecurely in memory:
|
||||
|
||||
* Palo Alto Networks GlobalProtect Agent 4.1.0 for Windows and GlobalProtect Agent 4.1.10 and earlier for macOS0.
|
||||
* Pulse Secure Connect Secure prior to 8.1R14, 8.2, 8.3R6, and 9.0R2.
|
||||
* Cisco AnyConnect 4.7.x and prior.
|
||||
|
||||
|
||||
|
||||
CERT says that Palo Alto Networks GlobalProtect version 4.1.1 [patches][8] this vulnerability.
|
||||
|
||||
In the CERT warning F5 stated it has been aware of the insecure memory storage since 2013 and has not yet been patched. More information can be found [here][9]. F5 also stated it has been aware of the insecure log storage since 2017 and fixed it in version 12.1.3 and 13.1.0 and onwards. More information can be found [here][10].
|
||||
|
||||
**[[Prepare to become a Certified Information Security Systems Professional with this comprehensive online course from PluralSight. Now offering a 10-day free trial!][11] ]**
|
||||
|
||||
CERT said it is unaware of any patches at the time of publishing for Cisco AnyConnect and Pulse Secure Connect Secure.
|
||||
|
||||
CERT credited the [National Defense ISAC Remote Access Working Group][12] for reporting the vulnerability.
|
||||
|
||||
Join the Network World communities on [Facebook][13] and [LinkedIn][14] to comment on topics that are top of mind.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.networkworld.com/article/3388646/gov-t-warns-on-vpn-security-bug-in-cisco-palo-alto-f5-pulse-software.html#tk.rss_all
|
||||
|
||||
作者：[Michael Cooney][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://www.networkworld.com/author/Michael-Cooney/
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://images.idgesg.net/images/article/2018/10/broken-chain_metal_link_breach_security-100777433-large.jpg
|
||||
[2]: https://www.networkworld.com/article/3268744/understanding-virtual-private-networks-and-why-vpns-are-important-to-sd-wan.html
|
||||
[3]: https://www.us-cert.gov/ncas/current-activity/2019/04/12/Vulnerability-Multiple-VPN-Applications
|
||||
[4]: https://www.networkworld.com/article/3236448/lan-wan/what-to-consider-when-deploying-a-next-generation-firewall.html
|
||||
[5]: https://www.networkworld.com/newsletters/signup.html
|
||||
[6]: https://www.kb.cert.org/vuls/id/192371/
|
||||
[7]: https://nvd.nist.gov/vuln/detail/CVE-2019-1573
|
||||
[8]: https://securityadvisories.paloaltonetworks.com/Home/Detail/146
|
||||
[9]: https://support.f5.com/csp/article/K14969
|
||||
[10]: https://support.f5.com/csp/article/K45432295
|
||||
[11]: https://pluralsight.pxf.io/c/321564/424552/7490?u=https%3A%2F%2Fwww.pluralsight.com%2Fpaths%2Fcertified-information-systems-security-professional-cisspr
|
||||
[12]: https://ndisac.org/workinggroups/
|
||||
[13]: https://www.facebook.com/NetworkWorld/
|
||||
[14]: https://www.linkedin.com/company/network-world
|
||||
75
sources/talk/20190415 Nyansa-s Voyance expands to the IoT.md
Normal file
75
sources/talk/20190415 Nyansa-s Voyance expands to the IoT.md
Normal file
@@ -0,0 +1,75 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (Nyansa’s Voyance expands to the IoT)
|
||||
[#]: via: (https://www.networkworld.com/article/3388301/nyansa-s-voyance-expands-to-the-iot.html#tk.rss_all)
|
||||
[#]: author: (Jon Gold https://www.networkworld.com/author/Jon-Gold/)
|
||||
|
||||
Nyansa’s Voyance expands to the IoT
|
||||
======
|
||||
|
||||
![Brandon Mowinkel \(CC0\)][1]
|
||||
|
||||
Nyansa announced today that their flagship Voyance product can now apply its AI-based secret sauce to [IoT][2] devices, over and above the networking equipment and IT endpoints it could already manage.
|
||||
|
||||
Voyance – a network management product that leverages AI to automate the discovery of devices on the network and identify unusual behavior – has been around for two years now, and Nyansa says that it’s being used to observe a total of 25 million client devices operating across roughly 200 customer networks.
|
||||
|
||||
**More on IoT:**
|
||||
|
||||
* [Most powerful Internet of Things companies][3]
|
||||
* [10 Hot IoT startups to watch][4]
|
||||
* [The 6 ways to make money in IoT][5]
|
||||
* [][6] [Blockchain, service-centric networking key to IoT success][7]
|
||||
* [Getting grounded in IoT networking and security][8]
|
||||
* [Building IoT-ready networks must become a priority][9]
|
||||
* [What is the Industrial IoT? [And why the stakes are so high]][10]
|
||||
|
||||
|
||||
|
||||
It’s a software-only product (available either via public SaaS or private cloud) that works by scanning a customer’s network and identifying every device attached to it, then establishing a behavioral baseline that will let it flag suspicious actions (e.g., sending a lot more data than other devices of its kind, connecting to unusual servers) and even perform automated root-cause analysis of network issues.
|
||||
|
||||
The process doesn’t happen instantaneously, particularly the creation of the baseline, but it’s designed to be minimally invasive to existing network management frameworks and easy to implement.
|
||||
|
||||
Nyansa said that the medical field has been one of the key targets for the newly IoT-enabled iteration of Voyance, and one early customer – Baptist Health, a Florida-based healthcare company that runs four hospitals and several other clinics and practices – said that Voyance IoT has offered a new level of visibility into the business’ complex array of connected diagnostic and treatment machines.
|
||||
|
||||
“In the past we didn’t have the ability to identify security concerns in this way, related to rogue devices on the enterprise network, and now we’re able to do that,” said CISO Thad Phillips.
|
||||
|
||||
While spiraling network complexity isn’t an issue confined to the IoT, there’s a strong argument that the number and variety of devices connected to an IoT-enabled network represent a new challenge to network management, particularly in light of the fact that many such devices aren’t particularly secure.
|
||||
|
||||
“They’re not manufactured by networking vendors or security vendors, so for a performance standpoint, they have a lot of quirks … and on the security side, that’s sort of a big problem there as well,” said Anand Srinivas, Nyansa’s co-founder and CTO.
|
||||
|
||||
Enabling the Voyance platform to identify and manage IoT devices along with traditional endpoints seems to be mostly a matter of adding new device signatures to the system, but Enterprise Management Associates research director Shamus McGillicuddy said that, while the system’s designed for automation and ease of use, AIOps products like Voyance do need to be managed to make sure that they’re functioning correctly.
|
||||
|
||||
“Anything based on machine learning is going to take a while to make sure it understands your environment and you might have to retrain it,” he said. “There’s always going to be more and more things connecting to IP networks, and it’s just going to be a question of building up a database.”
|
||||
|
||||
Voyance IoT is available now. Pricing starts at $16,000 per year, and goes up with the number of total devices managed. (Current Voyance users can manage up to 100 IoT devices at no additional cost.)
|
||||
|
||||
Join the Network World communities on [Facebook][11] and [LinkedIn][12] to comment on topics that are top of mind.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.networkworld.com/article/3388301/nyansa-s-voyance-expands-to-the-iot.html#tk.rss_all
|
||||
|
||||
作者：[Jon Gold][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://www.networkworld.com/author/Jon-Gold/
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://images.idgesg.net/images/article/2019/02/geometric_architecture_ceiling_structure_lines_connections_networks_perspective_by_brandon_mowinkel_cc0_via_unsplash_2400x1600-100788530-large.jpg
|
||||
[2]: https://www.networkworld.com/article/3207535/what-is-iot-how-the-internet-of-things-works.html
|
||||
[3]: https://www.networkworld.com/article/2287045/internet-of-things/wireless-153629-10-most-powerful-internet-of-things-companies.html
|
||||
[4]: https://www.networkworld.com/article/3270961/internet-of-things/10-hot-iot-startups-to-watch.html
|
||||
[5]: https://www.networkworld.com/article/3279346/internet-of-things/the-6-ways-to-make-money-in-iot.html
|
||||
[6]: https://www.networkworld.com/article/3280225/internet-of-things/what-is-digital-twin-technology-and-why-it-matters.html
|
||||
[7]: https://www.networkworld.com/article/3276313/internet-of-things/blockchain-service-centric-networking-key-to-iot-success.html
|
||||
[8]: https://www.networkworld.com/article/3269736/internet-of-things/getting-grounded-in-iot-networking-and-security.html
|
||||
[9]: https://www.networkworld.com/article/3276304/internet-of-things/building-iot-ready-networks-must-become-a-priority.html
|
||||
[10]: https://www.networkworld.com/article/3243928/internet-of-things/what-is-the-industrial-iot-and-why-the-stakes-are-so-high.html
|
||||
[11]: https://www.facebook.com/NetworkWorld/
|
||||
[12]: https://www.linkedin.com/company/network-world
|
||||
@@ -0,0 +1,59 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (Two tools to help visualize and simplify your data-driven operations)
|
||||
[#]: via: (https://www.networkworld.com/article/3389756/two-tools-to-help-visualize-and-simplify-your-data-driven-operations.html#tk.rss_all)
|
||||
[#]: author: (Kent McNeil, Vice President of Software, Ciena Blue Planet )
|
||||
|
||||
Two tools to help visualize and simplify your data-driven operations
|
||||
======
|
||||
Amidst the rising complexity of networks, and influx of data, service providers are striving to keep operational complexity under control. Blue Planet’s Kent McNeil explains how they can turn this challenge into a huge opportunity, and in fact reduce operational effort by exploiting state-of-the-art graph database visualization and delta-based federation technologies.
|
||||
![danleap][1]
|
||||
|
||||
**Build the picture: Visualize your data**
|
||||
|
||||
The Internet of Things (IoT), 5G, smart technology, virtual reality – all these applications guarantee one thing for communications service providers (CSPs): more data. As networks become increasingly overwhelmed by mounds of data, CSPs are on the hunt for ways to make the most of the intelligence collected and are looking for ways to monetize their services, provide more customizable offerings, and enhance their network performance.
|
||||
|
||||
Customer analytics has gone some way towards fulfilling this need for greater insights, but with the rise in the volume and variety of consumer and IoT applications, the influx of data will increase at a phenomenal rate. The data includes not only customer-related data, but also device and network data, adding complexity to the picture. CSPs must harness this information to understand the relationships between any two things, to understand the connections within their data and to ultimately, leverage it for a better customer experience.
|
||||
|
||||
**See the upward graphical trend with graph databases**
|
||||
|
||||
Traditional relational databases certainly have their use, but graph databases offer a novel perspective. The visual representation between the component parts enables CSPs to understand and analyze the characteristics, as well as to act in a timely manner when confronted with any discrepancies.
|
||||
|
||||
Graph databases can help CSPs tackle this new challenge, ensuring the data is not just stored, but also processed and analyzed. It enables complex network questions to be asked and answered, ensuring that CSPs are not sidelined as “dumb pipes” in the IoT movement.
|
||||
|
||||
The use of graph databases has started to become more mainstream, as businesses see the benefits. IBM conducted a generic industry study, entitled “The State of Graph Databases Worldwide”, which found that people are moving to graph databases for speed, performance enhancement of applications, and streamlined operations. Ways in which businesses are using, or are planning to use, graph technology is highest for network and IT operations, followed by master data management. Performance is a key factor for CSPs, as is personalization, which enables support for more tailored service offerings.
|
||||
|
||||
Another advantage of graph databases for CSPs is that of unravelling the complexity of network inventory in a clear, visualized picture – this capability gives CSPs a competitive advantage as speed and performance become increasingly paramount. This need for speed and reliability will increase tenfold as IoT continues its impressive global ramp-up. Operational complexity also grows as the influx of generated data produced by IoT will further challenge the scalability of existing operational environments. Graph databases can help CSPs tackle this new challenge, ensuring the data is not just stored, but also processed and analyzed. It enables complex network questions to be asked and answered, ensuring that CSPs are not sidelined as “dumb pipes” in the IoT movement.
|
||||
|
||||
**Change the tide of data with delta-based federation**
|
||||
|
||||
New data, updated data, corrected data, deleted data – all needs to be managed, in line with regulations, and instantaneously. But this capability does not exist in the reality of many CSP’s Operational Support Systems (OSS). Many still battle with updating data and relying on full uploads of network inventory in order to perform key service fulfillment and assurance tasks. This method is time-intensive and risky due to potential conflicts and inaccuracies. With data being accessed from a variety of systems, CSPs must have a way to effectively hone in on only what is required.
|
||||
|
||||
Integrating network data into one simplified system limits the impact on the legacy OSS systems. This allows each OSS to continue its specific role, yet to feed data into a single interface, hence enabling teams to see the complete picture and gain efficiencies while launching new services or pinpointing and resolving service and network issues.
|
||||
|
||||
A delta-based federation model ensures that an accurate picture is presented, and only essential changes are conducted reliably and quickly. This simplified method filters the delta changes, reducing the time involved in updating, and minimizing the system load and risks. A validation process takes place to catch any errors or issues with the data, so CSPs can apply checks and retain control over modifications. Integrating network data into one simplified system limits the impact on the legacy OSS systems. This allows each OSS to continue its specific role, yet to feed data into a single interface, hence enabling teams to see the complete picture and gain efficiencies while launching new services or pinpointing and resolving service and network issues.
|
||||
|
||||
**Ride the wave**
|
||||
|
||||
25 billion connected things are predicted by Gartner on a global scale by 2021 and CSPs are already struggling with the current levels of data, which Gartner estimates at 14.2 billion in 2019. Over the last decade, CSPs have faced significant rises in the levels of data consumed as demand for new services and higher bandwidth applications has taken off. This data wave is set to continue and CSPs have two important tools at their disposal helping them ride the wave. Firstly, CSPs have specialist, legacy OSS already in place which they can leverage as a basis for integrating data and implementing optimized systems. Secondly, they can utilize new technologies in database inventory management: graph databases and delta-based federation. The advantages of effectively integrating network data, visualizing it, and creating a clear map of the inter-connections, enable CSPs to make critical decisions more quickly and accurately, resulting in most optimized and informed service operations.
|
||||
|
||||
[Watch this video to learn more about Blue Planet][2]
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.networkworld.com/article/3389756/two-tools-to-help-visualize-and-simplify-your-data-driven-operations.html#tk.rss_all
|
||||
|
||||
作者：[Kent McNeil, Vice President of Software, Ciena Blue Planet][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://images.idgesg.net/images/article/2019/04/istock-165721901-100793858-large.jpg
|
||||
[2]: https://www.blueplanet.com/resources/IT-plus-network-now-a-powerhouse-combination.html?utm_campaign=X1058319&utm_source=NWW&utm_term=BPVideo&utm_medium=sponsoredpost4
|
||||
146
sources/talk/20190416 What SDN is and where it-s going.md
Normal file
146
sources/talk/20190416 What SDN is and where it-s going.md
Normal file
@@ -0,0 +1,146 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (What SDN is and where it’s going)
|
||||
[#]: via: (https://www.networkworld.com/article/3209131/what-sdn-is-and-where-its-going.html#tk.rss_all)
|
||||
[#]: author: (Michael Cooney https://www.networkworld.com/author/Michael-Cooney/)
|
||||
|
||||
What SDN is and where it’s going
|
||||
======
|
||||
Software-defined networking (SDN) established a foothold in cloud computing, intent-based networking, and network security, with Cisco, VMware, Juniper and others leading the charge.
|
||||
![seedkin / Getty Images][1]
|
||||
|
||||
Hardware reigned supreme in the networking world until the emergence of software-defined networking (SDN), a category of technologies that separate the network control plane from the forwarding plane to enable more automated provisioning and policy-based management of network resources.
|
||||
|
||||
SDN's origins can be traced to a research collaboration between Stanford University and the University of California at Berkeley that ultimately yielded the [OpenFlow][2] protocol in the 2008 timeframe.
|
||||
|
||||
**[Learn more about the[difference between SDN and NFV][3]. Get regularly scheduled insights by [signing up for Network World newsletters][4]]**
|
||||
|
||||
OpenFlow is only one of the first SDN canons, but it's a key component because it started the networking software revolution. OpenFlow defined a programmable network protocol that could help manage and direct traffic among routers and switches no matter which vendor made the underlying router or switch.
|
||||
|
||||
In the years since its inception, SDN has evolved into a reputable networking technology offered by key vendors including Cisco, VMware, Juniper, Pluribus and Big Switch. The Open Networking Foundation develops myriad open-source SDN technologies as well.
|
||||
|
||||
"Datacenter SDN no longer attracts breathless hype and fevered expectations, but the market is growing healthily, and its prospects remain robust," wrote Brad Casemore, IDC research vice president, data center networks, in a recent report, [_Worldwide Datacenter Software-Defined Networking Forecast, 2018–2022_][5]*. "*Datacenter modernization, driven by the relentless pursuit of digital transformation and characterized by the adoption of cloudlike infrastructure, will help to maintain growth, as will opportunities to extend datacenter SDN overlays and fabrics to multicloud application environments."
|
||||
|
||||
SDN will be increasingly perceived as a form of established, conventional networking, Casemore said.
|
||||
|
||||
IDC estimates that the worldwide data center SDN market will be worth more than $12 billion in 2022, recording a CAGR of 18.5% during the 2017–2022 period. The market generated revenue of nearly $5.15 billion in 2017, up more than 32.2% from 2016.
|
||||
|
||||
In 2017, the physical network represented the largest segment of the worldwide datacenter SDN market, accounting for revenue of nearly $2.2 billion, or about 42% of the overall total revenue. In 2022, however, the physical network is expected to claim about $3.65 billion in revenue, slightly less than the $3.68 billion attributable to network virtualization overlays/SDN controller software but more than the $3.18 billion for SDN applications.
|
||||
|
||||
“We're now at a point where SDN is better understood, where its use cases and value propositions are familiar to most datacenter network buyers and where a growing number of enterprises are finding that SDN offerings offer practical benefits,” Casemore said. “With SDN growth and the shift toward software-based network automation, the network is regaining lost ground and moving into better alignment with a wave of new application workloads that are driving meaningful business outcomes.”
|
||||
|
||||
### **What is SDN? **
|
||||
|
||||
The idea of programmability is the basis for the most precise definition of what SDN is: technology that separates the control plane management of network devices from the underlying data plane that forwards network traffic.
|
||||
|
||||
IDC broadens that definition of SDN by stating: “Datacenter SDN architectures feature software-defined overlays or controllers that are abstracted from the underlying network hardware, offering intent-or policy-based management of the network as a whole. This results in a datacenter network that is better aligned with the needs of application workloads through automated (thereby faster) provisioning, programmatic network management, pervasive application-oriented visibility, and where needed, direct integration with cloud orchestration platforms.”
|
||||
|
||||
The driving ideas behind the development of SDN are myriad. For example, it promises to reduce the complexity of statically defined networks; make automating network functions much easier; and allow for simpler provisioning and management of networked resources, everywhere from the data center to the campus or wide area network.
|
||||
|
||||
Separating the control and data planes is the most common way to think of what SDN is, but it is much more than that, said Mike Capuano, chief marketing officer for [Pluribus][6].
|
||||
|
||||
“At its heart SDN has a centralized or distributed intelligent entity that has an entire view of the network, that can make routing and switching decisions based on that view,” Capuano said. “Typically, network routers and switches only know about their neighboring network gear. But with a properly configured SDN environment, that central entity can control everything, from easily changing policies to simplifying configuration and automation across the enterprise.”
|
||||
|
||||
### How does SDN support edge computing, IoT and remote access?
|
||||
|
||||
A variety of networking trends have played into the central idea of SDN. Distributing computing power to remote sites, moving data center functions to the [edge][7], adopting cloud computing, and supporting [Internet of Things][8] environments – each of these efforts can be made easier and more cost efficient via a properly configured SDN environment.
|
||||
|
||||
Typically in an SDN environment, customers can see all of their devices and TCP flows, which means they can slice up the network from the data or management plane to support a variety of applications and configurations, Capuano said. So users can more easily segment an IoT application from the production world if they want, for example.
|
||||
|
||||
Some SDN controllers have the smarts to see that the network is getting congested and, in response, pump up bandwidth or processing to make sure remote and edge components don’t suffer latency.
|
||||
|
||||
SDN technologies also help in distributed locations that have few IT personnel on site, such as an enterprise branch office or service provider central office, said Michael Bushong, vice president of enterprise and cloud marketing at Juniper Networks.
|
||||
|
||||
“Naturally these places require remote and centralized delivery of connectivity, visibility and security. SDN solutions that centralize and abstract control and automate workflows across many places in the network, and their devices, improve operational reliability, speed and experience,” Bushong said.
|
||||
|
||||
### **How does SDN support intent-based networking?**
|
||||
|
||||
Intent-based networking ([IBN][9]) has a variety of components, but basically is about giving network administrators the ability to define what they want the network to do, and having an automated network management platform create the desired state and enforce policies to ensure what the business wants happens.
|
||||
|
||||
“If a key tenet of SDN is abstracted control over a fleet of infrastructure, then the provisioning paradigm and dynamic control to regulate infrastructure state is necessarily higher level,” Bushong said. “Policy is closer to declarative intent, moving away from the minutia of individual device details and imperative and reactive commands.”
|
||||
|
||||
IDC says that intent-based networking “represents an evolution of SDN to achieve even greater degrees of operational simplicity, automated intelligence, and closed-loop functionality.”
|
||||
|
||||
For that reason, IBN represents a notable milestone on the journey toward autonomous infrastructure that includes a self-driving network, which will function much like the self-driving car, producing desired outcomes based on what network operators and their organizations wish to accomplish, Casemore stated.
|
||||
|
||||
“While the self-driving car has been designed to deliver passengers safely to their destination with minimal human intervention, the self-driving network, as part of autonomous datacenter infrastructure, eventually will achieve similar outcomes in areas such as network provisioning, management, and troubleshooting — delivering applications and data, dynamically creating and altering network paths, and providing security enforcement with minimal need for operator intervention,” Casemore stated.
|
||||
|
||||
While IBN technologies are relatively young, Gartner says by 2020, more than 1,000 large enterprises will use intent-based networking systems in production, up from less than 15 in the second quarter of 2018.
|
||||
|
||||
### **How does SDN help customers with security?**
|
||||
|
||||
SDN enables a variety of security benefits. A customer can split up a network connection between an end user and the data center and have different security settings for the various types of network traffic. A network could have one public-facing, low security network that does not touch any sensitive information. Another segment could have much more fine-grained remote access control with software-based [firewall][10] and encryption policies on it, which allow sensitive data to traverse over it.
|
||||
|
||||
“For example, if a customer has an IoT group it doesn’t feel is all that mature with regards to security, via the SDN controller you can segment that group off away from the critical high-value corporate traffic,” Capuano stated. “SDN users can roll out security policies across the network from the data center to the edge and if you do all of this on top of white boxes, deployments can be 30 – 60 percent cheaper than traditional gear.”
|
||||
|
||||
The ability to look at a set of workloads and see if they match a given security policy is a key benefit of SDN, especially as data is distributed, said Thomas Scheibe, vice president of product management for Cisco’s Nexus and ACI product lines.
|
||||
|
||||
"The ability to deploy a whitelist security model like we do with ACI [Application Centric Infrastructure] that lets only specific entities access explicit resources across your network fabric is another key security element SDN enables," Scheibe said.
|
||||
|
||||
A growing number of SDN platforms now support [microsegmentation][11], according to Casemore.
|
||||
|
||||
“In fact, micro-segmentation has developed as a notable use case for SDN. As SDN platforms are extended to support multicloud environments, they will be used to mitigate the inherent complexity of establishing and maintaining consistent network and security policies across hybrid IT landscapes,” Casemore said.
|
||||
|
||||
### **What is SDN’s role in cloud computing?**
|
||||
|
||||
SDN’s role in the move toward [private cloud][12] and [hybrid cloud][13] adoption seems a natural. In fact, big SDN players such as Cisco, Juniper and VMware have all made moves to tie together enterprise data center and cloud worlds.
|
||||
|
||||
Cisco's ACI Anywhere package would, for example, let policies configured through Cisco's SDN APIC (Application Policy Infrastructure Controller) use native APIs offered by a public-cloud provider to orchestrate changes within both the private and public cloud environments, Cisco said.
|
||||
|
||||
“As organizations look to scale their hybrid cloud environments, it will be critical to leverage solutions that help improve productivity and processes,” said [Bob Laliberte][14], a senior analyst with Enterprise Strategy Group, in a recent [Network World article][15]. “The ability to leverage the same solution, like Cisco’s ACI, in your own private-cloud environment as well as across multiple public clouds will enable organizations to successfully scale their cloud environments.”
|
||||
|
||||
Growth of public and private clouds and enterprises' embrace of distributed multicloud application environments will have an ongoing and significant impact on data center SDN, representing both a challenge and an opportunity for vendors, said IDC’s Casemore.
|
||||
|
||||
“Agility is a key attribute of digital transformation, and enterprises will adopt architectures, infrastructures, and technologies that provide for agile deployment, provisioning, and ongoing operational management. In a datacenter networking context, the imperative of digital transformation drives adoption of extensive network automation, including SDN,” Casemore said.
|
||||
|
||||
### Where does SD-WAN fit in?
|
||||
|
||||
The software-defined wide area network ([SD-WAN][16]) is a natural application of SDN that extends the technology over a WAN. While the SDN architecture is typically the underpinning in a data center or campus, SD-WAN takes it a step further.
|
||||
|
||||
At its most basic, SD-WAN lets companies aggregate a variety of network connections – including MPLS, 4G LTE and DSL – into a branch or network edge location and have a software management platform that can turn up new sites, prioritize traffic and set security policies.
|
||||
|
||||
SD-WAN's driving principle is to simplify the way big companies turn up new links to branch offices, better manage the way those links are utilized – for data, voice or video – and potentially save money in the process.
|
||||
|
||||
[SD-WAN][17] lets networks route traffic based on centrally managed roles and rules, no matter what the entry and exit points of the traffic are, and with full security. For example, if a user in a branch office is working in Office365, SD-WAN can route their traffic directly to the closest cloud data center for that app, improving network responsiveness for the user and lowering bandwidth costs for the business.
|
||||
|
||||
"SD-WAN has been a promised technology for years, but in 2019 it will be a major driver in how networks are built and re-built," Anand Oswal, senior vice president of engineering in Cisco’s Enterprise Networking Business, said a Network World [article][18] earlier this year.
|
||||
|
||||
It's a profoundly hot market with tons of players including [Cisco][19], VMware, Silver Peak, Riverbed, Aryaka, Fortinet, Nokia and Versa.
|
||||
|
||||
IDC says the SD-WAN infrastructure market will hit $4.5 billion by 2022, growing at a more than 40% yearly clip between now and then.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.networkworld.com/article/3209131/what-sdn-is-and-where-its-going.html#tk.rss_all
|
||||
|
||||
作者：[Michael Cooney][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://www.networkworld.com/author/Michael-Cooney/
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://images.idgesg.net/images/article/2019/04/what-is-sdn_2_where-is-it-going_arrows_fork-in-the-road-100793314-large.jpg
|
||||
[2]: https://www.networkworld.com/article/2202144/data-center-faq-what-is-openflow-and-why-is-it-needed.html
|
||||
[3]: https://www.networkworld.com/article/3206709/lan-wan/what-s-the-difference-between-sdn-and-nfv.html
|
||||
[4]: https://www.networkworld.com/newsletters/signup.html
|
||||
[5]: https://www.idc.com/getdoc.jsp?containerId=US43862418
|
||||
[6]: https://www.networkworld.com/article/3192318/pluribus-recharges-expands-software-defined-network-platform.html
|
||||
[7]: https://www.networkworld.com/article/3224893/what-is-edge-computing-and-how-it-s-changing-the-network.html
|
||||
[8]: https://www.networkworld.com/article/3207535/what-is-iot-how-the-internet-of-things-works.html
|
||||
[9]: https://www.networkworld.com/article/3202699/what-is-intent-based-networking.html
|
||||
[10]: https://www.networkworld.com/article/3230457/what-is-a-firewall-perimeter-stateful-inspection-next-generation.html
|
||||
[11]: https://www.networkworld.com/article/3247672/what-is-microsegmentation-how-getting-granular-improves-network-security.html
|
||||
[12]: https://www.networkworld.com/article/2159885/cloud-computing-gartner-5-things-a-private-cloud-is-not.html
|
||||
[13]: https://www.networkworld.com/article/3233132/what-is-hybrid-cloud-computing.html
|
||||
[14]: https://www.linkedin.com/in/boblaliberte90/
|
||||
[15]: https://www.networkworld.com/article/3336075/cisco-serves-up-flexible-data-center-options.html
|
||||
[16]: https://www.networkworld.com/article/3031279/sd-wan-what-it-is-and-why-you-ll-use-it-one-day.html
|
||||
[17]: https://www.networkworld.com/article/3031279/sd-wan/sd-wan-what-it-is-and-why-you-ll-use-it-one-day.html
|
||||
[18]: https://www.networkworld.com/article/3332027/cisco-touts-5-technologies-that-will-change-networking-in-2019.html
|
||||
[19]: https://www.networkworld.com/article/3322937/what-will-be-hot-for-cisco-in-2019.html
|
||||
@@ -1,134 +0,0 @@
|
||||
FSSlc translating
|
||||
5 open source fonts ideal for programmers
|
||||
======
|
||||
|
||||
|
||||
|
||||
What is the best programming font? First, you need to consider that not all fonts are created equally. When choosing a font for casual reading, the reader expects the letters to smoothly flow into one another, giving an easy and enjoyable experience. A single character for a standard font is akin to puzzle piece designed to carefully mesh with every other part of the overall typeface.
|
||||
|
||||
When writing code, however, your font requirements are typically more functional in nature. This is why most programmers prefer to use monospaced fonts with fixed-width letters, when given the option. Selecting a font that has distinguishable numbers and punctuation, is aesthetically pleasing, and has a copyright license that meets your needs is also important.
|
||||
|
||||
There are certain features that make a font optimal for programming. First, a detailed definition of what makes a monospaced font is in order. Consider the letter "w" as it compares to the letter "i" for a moment. When you are dealing with a font, it is important to think about the whitespace around the letter, as well as the letter itself. In the world of physical books and newspapers, where efficient use of space is often critical, it makes sense to assign less width to the thin "i" than the wide "w."
|
||||
|
||||
There are certain features that make a font optimal for programming.
|
||||
|
||||
Inside a terminal, however, you are blessed with no such restrictions, and it can be very useful for every character to share an identical amount of space. The main functional benefit is that you can effectively "guesstimate" how long your code is by casually glancing at a block of text. Secondary benefits include the ability to align characters and punctuation easily, highlighting is much more visually obvious, and optical character recognition on printed sheets is more effective for monospaced fonts than proportional fonts.
|
||||
|
||||
Inside a terminal, however, you are blessed with no such restrictions, and it can be very useful for every character to share an identical amount of space. The main functional benefit is that you can effectively "guesstimate" how long your code is by casually glancing at a block of text. Secondary benefits include the ability to align characters and punctuation easily, highlighting is much more visually obvious, and optical character recognition on printed sheets is more effective for monospaced fonts than proportional fonts.
|
||||
|
||||
In this article we will explore five excellent open source font options that are ideal for programming and writing code.
|
||||
|
||||
### 1. Firacode: The best overall programming font
|
||||
|
||||
### [firacode.png][1]
|
||||
|
||||
![FiraCode example][2]
|
||||
|
||||
|
||||
FiraCode, Andrew Lekashman
|
||||
|
||||
### [firacode2.png][3]
|
||||
|
||||
![FiraCode compared to Fira Mono][4]
|
||||
|
||||
|
||||
FiraCode compared to Fira Mono, [Nikita Prokopov][5] via GitHub
|
||||
|
||||
### 2. Inconsolata: Elegant and created by a brilliant designer
|
||||
|
||||
### [inconsolata.png][6]
|
||||
|
||||
![Inconsolata example][7]
|
||||
|
||||
|
||||
Inconsolata, Andrew Lekashman
|
||||
|
||||
The first font on our list is [FiraCode][5] , a programming font that truly goes above and beyond the call of duty. FiraCode is an extension of Fira, the open source font family commissioned by Mozilla. What makes FiraCode different is that it modifies the common symbol combinations or ligatures used in code to be extraordinarily readable. This font family comes in several styles, notably including a Retina option. You can find examples for how it applies to many programming languages on its [GitHub][5] page.
|
||||
|
||||
[Inconsolata][8] is one of the most beautiful monospaced fonts. It has been around since 2006 as an open source and freely available option. The creator, Raph Levien designed Inconsolata with one basic statement in mind: "monospaced fonts do not have to suck." Two things that stand out about Inconsolata are its extremely clear differences between 0 and O and its well-defined punctuation.
|
||||
|
||||
### 3. DejaVu Sans Mono: Standard issue with many Linux distros and huge glyph coverage
|
||||
|
||||
### [dejavu_sans_mono.png][9]
|
||||
|
||||
![DejaVu Sans Mono example][10]
|
||||
|
||||
|
||||
DejaVu Sans Mono, Andrew Lekashman
|
||||
|
||||
Inspired by the copyrighted and closed Vera font family used in GNOME, [DejaVu Sans Mono][11] is an extremely popular programming font that comes bundled with nearly every modern Linux distribution. DejaVu comes packed with a whopping 3,310 glyphs under the Book Variant, compared to a standard font, which normally rests easy at around 100 glyphs. You'll have no shortage of characters to work with, it has enormous coverage over Unicode, and it is actively growing all of the time.
|
||||
|
||||
### 4. Source Code Pro: Elegant and readable, created by a small, talented team at Adobe
|
||||
|
||||
### [source_code_pro.png][12]
|
||||
|
||||
![Source Code Pro example][13]
|
||||
|
||||
|
||||
Source Code Pro, Andrew Lekashman
|
||||
|
||||
Designed by Paul Hunt and Teo Tuominen, [Source Code Pro][14] was [produced by Adobe][15] to be one of its first open source fonts. Source Code Pro is notable in that it is extremely readable and has excellent differentiation between potentially confusing characters and punctuation. Source Code Pro is also a font family and comes in seven different styles: Extralight, Light, Regular, Medium, Semibold, Bold, and Black, with italic variants of each.
|
||||
|
||||
### [source_code_pro2.png][16]
|
||||
|
||||
![Differentiating potentially confusable characters][17]
|
||||
|
||||
|
||||
Differentiating potentially confusable characters, [Paul D. Hunt][15] via Adobe Typekit Blog.
|
||||
|
||||
### [source_code_pro3.png][18]
|
||||
|
||||
![Metacharacters with special meaning in computer languages][19]
|
||||
|
||||
|
||||
Metacharacters with special meaning in computer languages, [Paul D. Hunt][15] via Adobe Typekit Blog
|
||||
|
||||
### 5. Noto Mono: Enormous language coverage, created by a large team at Google
|
||||
|
||||
### [noto.png][20]
|
||||
|
||||
![Noto Mono example][21]
|
||||
|
||||
|
||||
Noto Mono, Andrew Lekashman
|
||||
|
||||
The last font on our list is [Noto Mono][22], the monospaced version of the expansive Noto font family by Google. While not specifically designed for programming, Noto Mono is available in 209 languages (including emoji!) and is actively supported and updated. The project is enormous and is an extension of Google's stated mission to organize the world's information. If you want to learn more about it, check out this excellent [video about the font][23].
|
||||
|
||||
### Choosing the right font
|
||||
|
||||
Whichever typeface you select, you will most likely spend hours each day immersed within it, so make sure it resonates with you on an aesthetic and philosophical level. Choosing the right open source font is an important part of making sure that you have the best possible environment for productivity. Any of these fonts is a fantastic choice, and each option has a powerful feature set that lets it stand out from the rest.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/17/11/how-select-open-source-programming-font
|
||||
|
||||
作者：[Andrew Lekashman][a]
|
||||
译者：[FSSlc](https://github.com/FSSlc)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:https://opensource.com
|
||||
[1]:/https://opensource.comfile/377151
|
||||
[2]:https://opensource.com/sites/default/files/u128651/firacode.png (FiraCode example)
|
||||
[3]:https://opensource.com/file/377156
|
||||
[4]:https://opensource.com/sites/default/files/u128651/firacode2.png (FiraCode compared to Fira Mono)
|
||||
[5]:https://github.com/tonsky/FiraCode
|
||||
[6]:https://opensource.com/file/377161
|
||||
[7]:https://opensource.com/sites/default/files/u128651/inconsolata.png (Inconsolata example)
|
||||
[8]:http://www.levien.com/type/myfonts/inconsolata.html
|
||||
[9]:https://opensource.com/file/377146
|
||||
[10]:https://opensource.com/sites/default/files/u128651/dejavu_sans_mono.png (DejaVu Sans Mono example)
|
||||
[11]:https://dejavu-fonts.github.io/
|
||||
[12]:https://opensource.com/file/377171
|
||||
[13]:https://opensource.com/sites/default/files/u128651/source_code_pro.png (Source Code Pro example)
|
||||
[14]:https://github.com/adobe-fonts/source-code-pro
|
||||
[15]:https://blog.typekit.com/2012/09/24/source-code-pro/
|
||||
[16]:https://opensource.com/file/377176
|
||||
[17]:https://opensource.com/sites/default/files/u128651/source_code_pro2.png (Differentiating potentially confusable characters)
|
||||
[18]:https://opensource.com/file/377181
|
||||
[19]:https://opensource.com/sites/default/files/u128651/source_code_pro3.png (Metacharacters with special meaning in computer languages)
|
||||
[20]:https://opensource.com/file/377166
|
||||
[21]:https://opensource.com/sites/default/files/u128651/noto.png (Noto Mono example)
|
||||
[22]:https://www.google.com/get/noto/#mono-mono
|
||||
[23]:https://www.youtube.com/watch?v=AAzvk9HSi84
|
||||
@@ -1,12 +1,3 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: (pityonline)
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (Get Started with Snap Packages in Linux)
|
||||
[#]: via: (https://www.linux.com/learn/intro-to-linux/2018/5/get-started-snap-packages-linux)
|
||||
[#]: author: (Jack Wallen https://www.linux.com/users/jlwallen)
|
||||
|
||||
Get Started with Snap Packages in Linux
|
||||
======
|
||||
|
||||
@@ -148,7 +139,7 @@ via: https://www.linux.com/learn/intro-to-linux/2018/5/get-started-snap-packages
|
||||
|
||||
作者：[Jack Wallen][a]
|
||||
选题：[lujun9972](https://github.com/lujun9972)
|
||||
译者：[pityonline](https://github.com/pityonline)
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
@@ -1,4 +1,3 @@
|
||||
DaivdMax2006 is translating
|
||||
100 Best Ubuntu Apps
|
||||
======
|
||||
|
||||
|
||||
@@ -1,290 +0,0 @@
|
||||
Getting started with Sensu monitoring
|
||||
======
|
||||
|
||||
|
||||
Sensu is an open source infrastructure and application monitoring solution that monitors servers, services, and application health, and sends alerts and notifications with third-party integration. Written in Ruby, Sensu can use either [RabbitMQ][1] or [Redis][2] to handle messages. It uses Redis to store data.
|
||||
|
||||
If you want to monitor your cloud infrastructure in a simple and efficient manner, Sensu is a good option. It can be integrated with many of the modern DevOps stacks your organization may already be using, such as [Slack][3], [HipChat][4], or [IRC][5], and it can even send mobile/pager alerts with [PagerDuty][6].
|
||||
|
||||
Sensu's [modular architecture][7] means every component can be installed on the same server or on completely separate machines.
|
||||
|
||||
### Architecture
|
||||
|
||||
Sensu's main communication mechanism is the Transport. Every Sensu component must connect to the Transport in order to send messages to each other. Transport can use either RabbitMQ (recommended in production) or Redis.
|
||||
|
||||
Sensu Server processes event data and takes action. It registers clients and processes check results and monitoring events using filters, mutators, and handlers. The server publishes check definitions to the clients and the Sensu API provides a RESTful API, providing access to monitoring data and core functionality.
|
||||
|
||||
[Sensu Client][8] executes checks either scheduled by Sensu Server or local checks definitions. Sensu uses a data store (Redis) to keep all the persistent data. Finally, [Uchiwa][9] is the web interface to communicate with Sensu API.
|
||||
|
||||
![sensu_system.png][11]
|
||||
|
||||
### Installing Sensu
|
||||
|
||||
#### Prerequisites
|
||||
|
||||
* One Linux installation to act as the server node (I used CentOS 7 for this article)
|
||||
|
||||
* One or more Linux machines to monitor (clients)
|
||||
|
||||
|
||||
|
||||
|
||||
#### Server side
|
||||
|
||||
Sensu requires Redis to be installed. To install Redis, enable the EPEL repository:
|
||||
```
|
||||
$ sudo yum install epel-release -y
|
||||
|
||||
```
|
||||
|
||||
Then install Redis:
|
||||
```
|
||||
$ sudo yum install redis -y
|
||||
|
||||
```
|
||||
|
||||
Modify `/etc/redis.conf` to disable protected mode, listen on every interface, and set a password:
|
||||
```
|
||||
$ sudo sed -i 's/^protected-mode yes/protected-mode no/g' /etc/redis.conf
|
||||
|
||||
$ sudo sed -i 's/^bind 127.0.0.1/bind 0.0.0.0/g' /etc/redis.conf
|
||||
|
||||
$ sudo sed -i 's/^# requirepass foobared/requirepass password123/g' /etc/redis.conf
|
||||
|
||||
```
|
||||
|
||||
Enable and start Redis service:
|
||||
```
|
||||
$ sudo systemctl enable redis
|
||||
$ sudo systemctl start redis
|
||||
```
|
||||
|
||||
Redis is now installed and ready to be used by Sensu.
|
||||
|
||||
Now let’s install Sensu.
|
||||
|
||||
First, configure the Sensu repository and install the packages:
|
||||
```
|
||||
$ sudo tee /etc/yum.repos.d/sensu.repo << EOF
|
||||
[sensu]
|
||||
name=sensu
|
||||
baseurl=https://sensu.global.ssl.fastly.net/yum/\$releasever/\$basearch/
|
||||
gpgcheck=0
|
||||
enabled=1
|
||||
EOF
|
||||
|
||||
$ sudo yum install sensu uchiwa -y
|
||||
```
|
||||
|
||||
Let’s create the bare minimum configuration files for Sensu:
|
||||
```
|
||||
$ sudo tee /etc/sensu/conf.d/api.json << EOF
|
||||
{
|
||||
"api": {
|
||||
"host": "127.0.0.1",
|
||||
"port": 4567
|
||||
}
|
||||
}
|
||||
EOF
|
||||
```
|
||||
|
||||
Next, configure `sensu-api` to listen on localhost, with Port 4567:
|
||||
```
|
||||
$ sudo tee /etc/sensu/conf.d/redis.json << EOF
|
||||
{
|
||||
"redis": {
|
||||
"host": "<IP of server>",
|
||||
"port": 6379,
|
||||
"password": "password123"
|
||||
}
|
||||
}
|
||||
EOF
|
||||
|
||||
|
||||
$ sudo tee /etc/sensu/conf.d/transport.json << EOF
|
||||
{
|
||||
"transport": {
|
||||
"name": "redis"
|
||||
}
|
||||
}
|
||||
EOF
|
||||
```
|
||||
|
||||
In these two files, we configure Sensu to use Redis as the transport mechanism and the address where Redis will listen. Clients need to connect directly to the transport mechanism. These two files will be required on each client machine.
|
||||
```
|
||||
$ sudo tee /etc/sensu/uchiwa.json << EOF
|
||||
{
|
||||
"sensu": [
|
||||
{
|
||||
"name": "sensu",
|
||||
"host": "127.0.0.1",
|
||||
"port": 4567
|
||||
}
|
||||
],
|
||||
"uchiwa": {
|
||||
"host": "0.0.0.0",
|
||||
"port": 3000
|
||||
}
|
||||
}
|
||||
EOF
|
||||
```
|
||||
|
||||
In this file, we configure Uchiwa to listen on every interface (0.0.0.0) on Port 3000. We also configure Uchiwa to use `sensu-api` (already configured).
|
||||
|
||||
For security reasons, change the owner of the configuration files you just created:
|
||||
```
|
||||
$ sudo chown -R sensu:sensu /etc/sensu
|
||||
```
|
||||
|
||||
Enable and start the Sensu services:
|
||||
```
|
||||
$ sudo systemctl enable sensu-server sensu-api sensu-client
|
||||
$ sudo systemctl start sensu-server sensu-api sensu-client
|
||||
$ sudo systemctl enable uchiwa
|
||||
$ sudo systemctl start uchiwa
|
||||
```
|
||||
|
||||
Try accessing the Uchiwa website: http://<IP of server>:3000
|
||||
|
||||
For production environments, it’s recommended to run a cluster of RabbitMQ as the Transport instead of Redis (a Redis cluster can be used in production too), and to run more than one instance of Sensu Server and API for load balancing and high availability.
|
||||
|
||||
Sensu is now installed. Now let’s configure the clients.
|
||||
|
||||
#### Client side
|
||||
|
||||
To add a new client, you will need to enable Sensu repository on the client machines by creating the file `/etc/yum.repos.d/sensu.repo`.
|
||||
```
|
||||
$ sudo tee /etc/yum.repos.d/sensu.repo << EOF
|
||||
[sensu]
|
||||
name=sensu
|
||||
baseurl=https://sensu.global.ssl.fastly.net/yum/\$releasever/\$basearch/
|
||||
gpgcheck=0
|
||||
enabled=1
|
||||
EOF
|
||||
```
|
||||
|
||||
With the repository enabled, install the package Sensu:
|
||||
```
|
||||
$ sudo yum install sensu -y
|
||||
```
|
||||
|
||||
To configure `sensu-client`, create the same `redis.json` and `transport.json` created in the server machine, as well as the `client.json` configuration file:
|
||||
```
|
||||
$ sudo tee /etc/sensu/conf.d/client.json << EOF
|
||||
{
|
||||
"client": {
|
||||
"name": "rhel-client",
|
||||
"environment": "development",
|
||||
"subscriptions": [
|
||||
"frontend"
|
||||
]
|
||||
}
|
||||
}
|
||||
EOF
|
||||
```
|
||||
|
||||
In the name field, specify a name to identify this client (typically the hostname). The environment field can help you filter, and subscription defines which monitoring checks will be executed by the client.
|
||||
|
||||
Finally, enable and start the services and check in Uchiwa, as the new client will register automatically:
|
||||
```
|
||||
$ sudo systemctl enable sensu-client
|
||||
$ sudo systemctl start sensu-client
|
||||
```
|
||||
|
||||
### Sensu checks
|
||||
|
||||
Sensu checks have two components: a plugin and a definition.
|
||||
|
||||
Sensu is compatible with the [Nagios check plugin specification][12], so any check for Nagios can be used without modification. Checks are executable files and are run by the Sensu client.
|
||||
|
||||
Check definitions let Sensu know how, where, and when to run the plugin.
|
||||
|
||||
#### Client side
|
||||
|
||||
Let’s install one check plugin on the client machine. Remember, this plugin will be executed on the clients.
|
||||
|
||||
Enable EPEL and install `nagios-plugins-http` :
|
||||
```
|
||||
$ sudo yum install -y epel-release
|
||||
$ sudo yum install -y nagios-plugins-http
|
||||
```
|
||||
|
||||
Now let’s explore the plugin by executing it manually. Try checking the status of a web server running on the client machine. It should fail as we don’t have a web server running:
|
||||
```
|
||||
$ /usr/lib64/nagios/plugins/check_http -I 127.0.0.1
|
||||
connect to address 127.0.0.1 and port 80: Connection refused
|
||||
HTTP CRITICAL - Unable to open TCP socket
|
||||
```
|
||||
|
||||
It failed, as expected. Check the return code of the execution:
|
||||
```
|
||||
$ echo $?
|
||||
2
|
||||
|
||||
```
|
||||
|
||||
The Nagios check plugin specification defines four return codes for the plugin execution:
|
||||
|
||||
| **Plugin return code** | **State** |
|
||||
|------------------------|-----------|
|
||||
| 0 | OK |
|
||||
| 1 | WARNING |
|
||||
| 2 | CRITICAL |
|
||||
| 3 | UNKNOWN |
|
||||
|
||||
With this information, we can now create the check definition on the server.
|
||||
|
||||
#### Server side
|
||||
|
||||
On the server machine, create the file `/etc/sensu/conf.d/check_http.json`:
|
||||
```
|
||||
{
|
||||
"checks": {
|
||||
"check_http": {
|
||||
"command": "/usr/lib64/nagios/plugins/check_http -I 127.0.0.1",
|
||||
"interval": 10,
|
||||
"subscribers": [
|
||||
"frontend"
|
||||
]
|
||||
}
|
||||
}
|
||||
}
|
||||
```
|
||||
|
||||
In the command field, use the command we tested before. `Interval` will tell Sensu how frequently, in seconds, this check should be executed. Finally, `subscribers` will define the clients where the check will be executed.
|
||||
|
||||
Restart both sensu-api and sensu-server and confirm that the new check is available in Uchiwa.
|
||||
```
|
||||
$ sudo systemctl restart sensu-api sensu-server
|
||||
```
|
||||
|
||||
### What’s next?
|
||||
|
||||
Sensu is a powerful tool, and this article covers just a glimpse of what it can do. See the [documentation][13] to learn more, and visit the Sensu site to learn more about the [Sensu community][14].
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/18/8/getting-started-sensu-monitoring-solution
|
||||
|
||||
作者：[Michael Zamot][a]
|
||||
选题：[lujun9972](https://github.com/lujun9972)
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:https://opensource.com/users/mzamot
|
||||
[1]:https://www.rabbitmq.com/
|
||||
[2]:https://redis.io/topics/config
|
||||
[3]:https://slack.com/
|
||||
[4]:https://en.wikipedia.org/wiki/HipChat
|
||||
[5]:http://www.irc.org/
|
||||
[6]:https://www.pagerduty.com/
|
||||
[7]:https://docs.sensu.io/sensu-core/1.4/overview/architecture/
|
||||
[8]:https://docs.sensu.io/sensu-core/1.4/installation/install-sensu-client/
|
||||
[9]:https://uchiwa.io/#/
|
||||
[10]:/file/406576
|
||||
[11]:https://opensource.com/sites/default/files/uploads/sensu_system.png (sensu_system.png)
|
||||
[12]:https://assets.nagios.com/downloads/nagioscore/docs/nagioscore/4/en/pluginapi.html
|
||||
[13]:https://docs.sensu.io/
|
||||
[14]:https://sensu.io/community
|
||||
@@ -1,3 +1,4 @@
|
||||
liujing97 is translating
|
||||
Working with data streams on the Linux command line
|
||||
======
|
||||
Learn to connect data streams from one utility to another using STDIO.
|
||||
|
||||
@@ -1,359 +0,0 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: (liujing97)
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (How To Understand And Identify File types in Linux)
|
||||
[#]: via: (https://www.2daygeek.com/how-to-understand-and-identify-file-types-in-linux/)
|
||||
[#]: author: (Magesh Maruthamuthu https://www.2daygeek.com/author/magesh/)
|
||||
|
||||
How To Understand And Identify File types in Linux
|
||||
======
|
||||
|
||||
We all are knows, that everything is a file in Linux which includes Hard Disk, Graphics Card, etc.
|
||||
|
||||
When you are navigating the Linux filesystem most of the files are fall under regular files and directories.
|
||||
|
||||
But it has other file types as well for different purpose which fall in five categories.
|
||||
|
||||
So, it’s very important to understand the file types in Linux that helps you in many ways.
|
||||
|
||||
If you can’t believe this, you just gone through the complete article then you come to know how important is.
|
||||
|
||||
If you don’t understand the file types you can’t make any changes on that without fear.
|
||||
|
||||
If you made the changes wrongly that damage your system very badly so be careful when you are doing that.
|
||||
|
||||
Files are very important in Linux because all the devices and daemon’s were stored as a file in Linux system.
|
||||
|
||||
### How Many Types of File is Available in Linux?
|
||||
|
||||
As per my knowledge, totally 7 types of files are available in Linux with 3 Major categories. The details are below.
|
||||
|
||||
* Regular File
|
||||
* Directory File
|
||||
* Special Files (This category having five type of files)
|
||||
* Link File
|
||||
* Character Device File
|
||||
* Socket File
|
||||
* Named Pipe File
|
||||
* Block File
|
||||
|
||||
|
||||
|
||||
Refer the below table for better understanding of file types in Linux.
|
||||
| Symbol | Meaning |
|
||||
| – | Regular File. It starts with underscore “_”. |
|
||||
| d | Directory File. It starts with English alphabet letter “d”. |
|
||||
| l | Link File. It starts with English alphabet letter “l”. |
|
||||
| c | Character Device File. It starts with English alphabet letter “c”. |
|
||||
| s | Socket File. It starts with English alphabet letter “s”. |
|
||||
| p | Named Pipe File. It starts with English alphabet letter “p”. |
|
||||
| b | Block File. It starts with English alphabet letter “b”. |
|
||||
|
||||
### Method-1: Manual Way to Identify File types in Linux
|
||||
|
||||
If you are having good knowledge in Linux then you can easily identify the files type with help of above table.
|
||||
|
||||
#### How to view the Regular files in Linux?
|
||||
|
||||
Use the below command to view the Regular files in Linux. Regular files are available everywhere in Linux filesystem.
|
||||
The Regular files color is `WHITE`
|
||||
|
||||
```
|
||||
# ls -la | grep ^-
|
||||
-rw-------. 1 mageshm mageshm 1394 Jan 18 15:59 .bash_history
|
||||
-rw-r--r--. 1 mageshm mageshm 18 May 11 2012 .bash_logout
|
||||
-rw-r--r--. 1 mageshm mageshm 176 May 11 2012 .bash_profile
|
||||
-rw-r--r--. 1 mageshm mageshm 124 May 11 2012 .bashrc
|
||||
-rw-r--r--. 1 root root 26 Dec 27 17:55 liks
|
||||
-rw-r--r--. 1 root root 104857600 Jan 31 2006 test100.dat
|
||||
-rw-r--r--. 1 root root 104874307 Dec 30 2012 test100.zip
|
||||
-rw-r--r--. 1 root root 11536384 Dec 30 2012 test10.zip
|
||||
-rw-r--r--. 1 root root 61 Dec 27 19:05 test2-bzip2.txt
|
||||
-rw-r--r--. 1 root root 61 Dec 31 14:24 test3-bzip2.txt
|
||||
-rw-r--r--. 1 root root 60 Dec 27 19:01 test-bzip2.txt
|
||||
```
|
||||
|
||||
#### How to view the Directory files in Linux?
|
||||
|
||||
Use the below command to view the Directory files in Linux. Directory files are available everywhere in Linux filesystem. The Directory files colour is `BLUE`
|
||||
|
||||
```
|
||||
# ls -la | grep ^d
|
||||
drwxr-xr-x. 3 mageshm mageshm 4096 Dec 31 14:24 links/
|
||||
drwxrwxr-x. 2 mageshm mageshm 4096 Nov 16 15:44 perl5/
|
||||
drwxr-xr-x. 2 mageshm mageshm 4096 Nov 16 15:37 public_ftp/
|
||||
drwxr-xr-x. 3 mageshm mageshm 4096 Nov 16 15:37 public_html/
|
||||
```
|
||||
|
||||
#### How to view the Link files in Linux?
|
||||
|
||||
Use the below command to view the Link files in Linux. Link files are available everywhere in Linux filesystem.
|
||||
Two type of link files are available, it’s Soft link and Hard link. The Link files color is `LIGHT TURQUOISE`
|
||||
|
||||
```
|
||||
# ls -la | grep ^l
|
||||
lrwxrwxrwx. 1 root root 31 Dec 7 15:11 s-link-file -> /links/soft-link/test-soft-link
|
||||
lrwxrwxrwx. 1 root root 38 Dec 7 15:12 s-link-folder -> /links/soft-link/test-soft-link-folder
|
||||
```
|
||||
|
||||
#### How to view the Character Device files in Linux?
|
||||
|
||||
Use the below command to view the Character Device files in Linux. Character Device files are available only in specific location.
|
||||
|
||||
It’s available under `/dev` directory. The Character Device files color is `YELLOW`
|
||||
|
||||
```
|
||||
# ls -la | grep ^c
|
||||
crw-------. 1 root root 5, 1 Jan 28 14:05 console
|
||||
crw-rw----. 1 root root 10, 61 Jan 28 14:05 cpu_dma_latency
|
||||
crw-rw----. 1 root root 10, 62 Jan 28 14:05 crash
|
||||
crw-rw----. 1 root root 29, 0 Jan 28 14:05 fb0
|
||||
crw-rw-rw-. 1 root root 1, 7 Jan 28 14:05 full
|
||||
crw-rw-rw-. 1 root root 10, 229 Jan 28 14:05 fuse
|
||||
```
|
||||
|
||||
#### How to view the Block files in Linux?
|
||||
|
||||
Use the below command to view the Block files in Linux. The Block files are available only in specific location.
|
||||
It’s available under `/dev` directory. The Block files color is `YELLOW`
|
||||
|
||||
```
|
||||
# ls -la | grep ^b
|
||||
brw-rw----. 1 root disk 7, 0 Jan 28 14:05 loop0
|
||||
brw-rw----. 1 root disk 7, 1 Jan 28 14:05 loop1
|
||||
brw-rw----. 1 root disk 7, 2 Jan 28 14:05 loop2
|
||||
brw-rw----. 1 root disk 7, 3 Jan 28 14:05 loop3
|
||||
brw-rw----. 1 root disk 7, 4 Jan 28 14:05 loop4
|
||||
```
|
||||
|
||||
#### How to view the Socket files in Linux?
|
||||
|
||||
Use the below command to view the Socket files in Linux. The Socket files are available only in specific location.
|
||||
The Socket files color is `PINK`
|
||||
|
||||
```
|
||||
# ls -la | grep ^s
|
||||
srw-rw-rw- 1 root root 0 Jan 5 16:36 system_bus_socket
|
||||
```
|
||||
|
||||
#### How to view the Named Pipe files in Linux?
|
||||
|
||||
Use the below command to view the Named Pipe files in Linux. The Named Pipe files are available only in specific location. The Named Pipe files color is `YELLOW`
|
||||
|
||||
```
|
||||
# ls -la | grep ^p
|
||||
prw-------. 1 root root 0 Jan 28 14:06 replication-notify-fifo|
|
||||
prw-------. 1 root root 0 Jan 28 14:06 stats-mail|
|
||||
```
|
||||
|
||||
### Method-2: How to Identify File types in Linux Using file Command?
|
||||
|
||||
The file command allow us to determine various file types in Linux. There are three sets of tests, performed in this order: filesystem tests, magic tests, and language tests to identify file types.
|
||||
|
||||
#### How to view the Regular files in Linux Using file Command?
|
||||
|
||||
Simple enter the file command on your terminal and followed by Regular file. The file command will read the given file contents and display exactly what kind of file it is.
|
||||
|
||||
That’s why we are seeing different results for each Regular files. See the below various results for Regular files.
|
||||
|
||||
```
|
||||
# file 2daygeek_access.log
|
||||
2daygeek_access.log: ASCII text, with very long lines
|
||||
|
||||
# file powertop.html
|
||||
powertop.html: HTML document, ASCII text, with very long lines
|
||||
|
||||
# file 2g-test
|
||||
2g-test: JSON data
|
||||
|
||||
# file powertop.txt
|
||||
powertop.txt: HTML document, UTF-8 Unicode text, with very long lines
|
||||
|
||||
# file 2g-test-05-01-2019.tar.gz
|
||||
2g-test-05-01-2019.tar.gz: gzip compressed data, last modified: Sat Jan 5 18:22:20 2019, from Unix, original size 450560
|
||||
```
|
||||
|
||||
#### How to view the Directory files in Linux Using file Command?
|
||||
|
||||
Simple enter the file command on your terminal and followed by Directory file. See the results below.
|
||||
|
||||
```
|
||||
# file Pictures/
|
||||
Pictures/: directory
|
||||
```
|
||||
|
||||
#### How to view the Link files in Linux Using file Command?
|
||||
|
||||
Simple enter the file command on your terminal and followed by Link file. See the results below.
|
||||
|
||||
```
|
||||
# file log
|
||||
log: symbolic link to /run/systemd/journal/dev-log
|
||||
```
|
||||
|
||||
#### How to view the Character Device files in Linux Using file Command?
|
||||
|
||||
Simple enter the file command on your terminal and followed by Character Device file. See the results below.
|
||||
|
||||
```
|
||||
# file vcsu
|
||||
vcsu: character special (7/64)
|
||||
```
|
||||
|
||||
#### How to view the Block files in Linux Using file Command?
|
||||
|
||||
Simple enter the file command on your terminal and followed by Block file. See the results below.
|
||||
|
||||
```
|
||||
# file sda1
|
||||
sda1: block special (8/1)
|
||||
```
|
||||
|
||||
#### How to view the Socket files in Linux Using file Command?
|
||||
|
||||
Simple enter the file command on your terminal and followed by Socket file. See the results below.
|
||||
|
||||
```
|
||||
# file system_bus_socket
|
||||
system_bus_socket: socket
|
||||
```
|
||||
|
||||
#### How to view the Named Pipe files in Linux Using file Command?
|
||||
|
||||
Simple enter the file command on your terminal and followed by Named Pipe file. See the results below.
|
||||
|
||||
```
|
||||
# file pipe-test
|
||||
pipe-test: fifo (named pipe)
|
||||
```
|
||||
|
||||
### Method-3: How to Identify File types in Linux Using stat Command?
|
||||
|
||||
The stat command allow us to check file types or file system status. This utility giving more information than file command. It shows lot of information about the given file such as Size, Block Size, IO Block Size, Inode Value, Links, File permission, UID, GID, File Access, Modify and Change time details.
|
||||
|
||||
#### How to view the Regular files in Linux Using stat Command?
|
||||
|
||||
Simple enter the stat command on your terminal and followed by Regular file.
|
||||
|
||||
```
|
||||
# stat 2daygeek_access.log
|
||||
File: 2daygeek_access.log
|
||||
Size: 14406929 Blocks: 28144 IO Block: 4096 regular file
|
||||
Device: 10301h/66305d Inode: 1727555 Links: 1
|
||||
Access: (0644/-rw-r--r--) Uid: ( 1000/ daygeek) Gid: ( 1000/ daygeek)
|
||||
Access: 2019-01-03 14:05:26.430328867 +0530
|
||||
Modify: 2019-01-03 14:05:26.460328868 +0530
|
||||
Change: 2019-01-03 14:05:26.460328868 +0530
|
||||
Birth: -
|
||||
```
|
||||
|
||||
#### How to view the Directory files in Linux Using stat Command?
|
||||
|
||||
Simple enter the stat command on your terminal and followed by Directory file. See the results below.
|
||||
|
||||
```
|
||||
# stat Pictures/
|
||||
File: Pictures/
|
||||
Size: 4096 Blocks: 8 IO Block: 4096 directory
|
||||
Device: 10301h/66305d Inode: 1703982 Links: 3
|
||||
Access: (0755/drwxr-xr-x) Uid: ( 1000/ daygeek) Gid: ( 1000/ daygeek)
|
||||
Access: 2018-11-24 03:22:11.090000828 +0530
|
||||
Modify: 2019-01-05 18:27:01.546958817 +0530
|
||||
Change: 2019-01-05 18:27:01.546958817 +0530
|
||||
Birth: -
|
||||
```
|
||||
|
||||
#### How to view the Link files in Linux Using stat Command?
|
||||
|
||||
Simple enter the stat command on your terminal and followed by Link file. See the results below.
|
||||
|
||||
```
|
||||
# stat /dev/log
|
||||
File: /dev/log -> /run/systemd/journal/dev-log
|
||||
Size: 28 Blocks: 0 IO Block: 4096 symbolic link
|
||||
Device: 6h/6d Inode: 278 Links: 1
|
||||
Access: (0777/lrwxrwxrwx) Uid: ( 0/ root) Gid: ( 0/ root)
|
||||
Access: 2019-01-05 16:36:31.033333447 +0530
|
||||
Modify: 2019-01-05 16:36:30.766666768 +0530
|
||||
Change: 2019-01-05 16:36:30.766666768 +0530
|
||||
Birth: -
|
||||
```
|
||||
|
||||
#### How to view the Character Device files in Linux Using stat Command?
|
||||
|
||||
Simple enter the stat command on your terminal and followed by Character Device file. See the results below.
|
||||
|
||||
```
|
||||
# stat /dev/vcsu
|
||||
File: /dev/vcsu
|
||||
Size: 0 Blocks: 0 IO Block: 4096 character special file
|
||||
Device: 6h/6d Inode: 16 Links: 1 Device type: 7,40
|
||||
Access: (0660/crw-rw----) Uid: ( 0/ root) Gid: ( 5/ tty)
|
||||
Access: 2019-01-05 16:36:31.056666781 +0530
|
||||
Modify: 2019-01-05 16:36:31.056666781 +0530
|
||||
Change: 2019-01-05 16:36:31.056666781 +0530
|
||||
Birth: -
|
||||
```
|
||||
|
||||
#### How to view the Block files in Linux Using stat Command?
|
||||
|
||||
Simple enter the stat command on your terminal and followed by Block file. See the results below.
|
||||
|
||||
```
|
||||
# stat /dev/sda1
|
||||
File: /dev/sda1
|
||||
Size: 0 Blocks: 0 IO Block: 4096 block special file
|
||||
Device: 6h/6d Inode: 250 Links: 1 Device type: 8,1
|
||||
Access: (0660/brw-rw----) Uid: ( 0/ root) Gid: ( 994/ disk)
|
||||
Access: 2019-01-05 16:36:31.596666806 +0530
|
||||
Modify: 2019-01-05 16:36:31.596666806 +0530
|
||||
Change: 2019-01-05 16:36:31.596666806 +0530
|
||||
Birth: -
|
||||
```
|
||||
|
||||
#### How to view the Socket files in Linux Using stat Command?
|
||||
|
||||
Simple enter the stat command on your terminal and followed by Socket file. See the results below.
|
||||
|
||||
```
|
||||
# stat /var/run/dbus/system_bus_socket
|
||||
File: /var/run/dbus/system_bus_socket
|
||||
Size: 0 Blocks: 0 IO Block: 4096 socket
|
||||
Device: 15h/21d Inode: 576 Links: 1
|
||||
Access: (0666/srw-rw-rw-) Uid: ( 0/ root) Gid: ( 0/ root)
|
||||
Access: 2019-01-05 16:36:31.823333482 +0530
|
||||
Modify: 2019-01-05 16:36:31.810000149 +0530
|
||||
Change: 2019-01-05 16:36:31.810000149 +0530
|
||||
Birth: -
|
||||
```
|
||||
|
||||
#### How to view the Named Pipe files in Linux Using stat Command?
|
||||
|
||||
Simple enter the stat command on your terminal and followed by Named Pipe file. See the results below.
|
||||
|
||||
```
|
||||
# stat pipe-test
|
||||
File: pipe-test
|
||||
Size: 0 Blocks: 0 IO Block: 4096 fifo
|
||||
Device: 10301h/66305d Inode: 1705583 Links: 1
|
||||
Access: (0644/prw-r--r--) Uid: ( 1000/ daygeek) Gid: ( 1000/ daygeek)
|
||||
Access: 2019-01-06 02:00:03.040394731 +0530
|
||||
Modify: 2019-01-06 02:00:03.040394731 +0530
|
||||
Change: 2019-01-06 02:00:03.040394731 +0530
|
||||
Birth: -
|
||||
```
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.2daygeek.com/how-to-understand-and-identify-file-types-in-linux/
|
||||
|
||||
作者：[Magesh Maruthamuthu][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[liujing97](https://github.com/liujing97)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://www.2daygeek.com/author/magesh/
|
||||
[b]: https://github.com/lujun9972
|
||||
@@ -1,159 +0,0 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: (liujing97)
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (7 Methods To Identify Disk Partition/FileSystem UUID On Linux)
|
||||
[#]: via: (https://www.2daygeek.com/check-partitions-uuid-filesystem-uuid-universally-unique-identifier-linux/)
|
||||
[#]: author: (Magesh Maruthamuthu https://www.2daygeek.com/author/magesh/)
|
||||
|
||||
7 Methods To Identify Disk Partition/FileSystem UUID On Linux
|
||||
======
|
||||
|
||||
As a Linux administrator you should aware of that how do you check partition UUID or filesystem UUID.
|
||||
|
||||
Because most of the Linux systems are mount the partitions with UUID. The same has been verified in the `/etc/fstab` file.
|
||||
|
||||
There are many utilities are available to check UUID. In this article we will show you how to check UUID in many ways and you can choose the one which is suitable for you.
|
||||
|
||||
### What Is UUID?
|
||||
|
||||
UUID stands for Universally Unique Identifier which helps Linux system to identify a hard drives partition instead of block device file.
|
||||
|
||||
libuuid is part of the util-linux-ng package since kernel version 2.15.1 and it’s installed by default in Linux system.
|
||||
|
||||
The UUIDs generated by this library can be reasonably expected to be unique within a system, and unique across all systems.
|
||||
|
||||
It’s a 128 bit number used to identify information in computer systems. UUIDs were originally used in the Apollo Network Computing System (NCS) and later UUIDs are standardized by the Open Software Foundation (OSF) as part of the Distributed Computing Environment (DCE).
|
||||
|
||||
UUIDs are represented as 32 hexadecimal (base 16) digits, displayed in five groups separated by hyphens, in the form 8-4-4-4-12 for a total of 36 characters (32 alphanumeric characters and four hyphens).
|
||||
|
||||
For example: d92fa769-e00f-4fd7-b6ed-ecf7224af7fa
|
||||
|
||||
Sample of my /etc/fstab file.
|
||||
|
||||
```
|
||||
# cat /etc/fstab
|
||||
|
||||
# /etc/fstab: static file system information.
|
||||
#
|
||||
# Use 'blkid' to print the universally unique identifier for a device; this may
|
||||
# be used with UUID= as a more robust way to name devices that works even if
|
||||
# disks are added and removed. See fstab(5).
|
||||
#
|
||||
#
|
||||
UUID=69d9dd18-36be-4631-9ebb-78f05fe3217f / ext4 defaults,noatime 0 1
|
||||
UUID=a2092b92-af29-4760-8e68-7a201922573b swap swap defaults,noatime 0 2
|
||||
```
|
||||
|
||||
We can check this using the following seven commands.
|
||||
|
||||
* **`blkid Command:`** locate/print block device attributes.
|
||||
* **`lsblk Command:`** lsblk lists information about all available or the specified block devices.
|
||||
* **`hwinfo Command:`** hwinfo stands for hardware information tool is another great utility that used to probe for the hardware present in the system.
|
||||
* **`udevadm Command:`** udev management tool.
|
||||
* **`tune2fs Command:`** adjust tunable filesystem parameters on ext2/ext3/ext4 filesystems.
|
||||
* **`dumpe2fs Command:`** dump ext2/ext3/ext4 filesystem information.
|
||||
* **`Using by-uuid Path:`** The directory contains UUID and real block device files, UUIDs were symlink with real block device files.
|
||||
|
||||
|
||||
|
||||
### How To Check Disk Partition/FileSystem UUID In Linux Uusing blkid Command?
|
||||
|
||||
blkid is a command-line utility to locate/print block device attributes. It uses libblkid library to get disk partition UUID in Linux system.
|
||||
|
||||
```
|
||||
# blkid
|
||||
/dev/sda1: UUID="d92fa769-e00f-4fd7-b6ed-ecf7224af7fa" TYPE="ext4" PARTUUID="eab59449-01"
|
||||
/dev/sdc1: UUID="d17e3c31-e2c9-4f11-809c-94a549bc43b7" TYPE="ext2" PARTUUID="8cc8f9e5-01"
|
||||
/dev/sdc3: UUID="ca307aa4-0866-49b1-8184-004025789e63" TYPE="ext4" PARTUUID="8cc8f9e5-03"
|
||||
/dev/sdc5: PARTUUID="8cc8f9e5-05"
|
||||
```
|
||||
|
||||
### How To Check Disk Partition/FileSystem UUID In Linux Uusing lsblk Command?
|
||||
|
||||
lsblk lists information about all available or the specified block devices. The lsblk command reads the sysfs filesystem and udev db to gather information.
|
||||
|
||||
If the udev db is not available or lsblk is compiled without udev support than it tries to read LABELs, UUIDs and filesystem types from the block device. In this case root permissions are necessary. The command prints all block devices (except RAM disks) in a tree-like format by default.
|
||||
|
||||
```
|
||||
# lsblk -o name,mountpoint,size,uuid
|
||||
NAME MOUNTPOINT SIZE UUID
|
||||
sda 30G
|
||||
└─sda1 / 20G d92fa769-e00f-4fd7-b6ed-ecf7224af7fa
|
||||
sdb 10G
|
||||
sdc 10G
|
||||
├─sdc1 1G d17e3c31-e2c9-4f11-809c-94a549bc43b7
|
||||
├─sdc3 1G ca307aa4-0866-49b1-8184-004025789e63
|
||||
├─sdc4 1K
|
||||
└─sdc5 1G
|
||||
sdd 10G
|
||||
sde 10G
|
||||
sr0 1024M
|
||||
```
|
||||
|
||||
### How To Check Disk Partition/FileSystem UUID In Linux Uusing by-uuid path?
|
||||
|
||||
The directory contains UUID and real block device files, UUIDs were symlink with real block device files.
|
||||
|
||||
```
|
||||
# ls -lh /dev/disk/by-uuid/
|
||||
total 0
|
||||
lrwxrwxrwx 1 root root 10 Jan 29 08:34 ca307aa4-0866-49b1-8184-004025789e63 -> ../../sdc3
|
||||
lrwxrwxrwx 1 root root 10 Jan 29 08:34 d17e3c31-e2c9-4f11-809c-94a549bc43b7 -> ../../sdc1
|
||||
lrwxrwxrwx 1 root root 10 Jan 29 08:34 d92fa769-e00f-4fd7-b6ed-ecf7224af7fa -> ../../sda1
|
||||
```
|
||||
|
||||
### How To Check Disk Partition/FileSystem UUID In Linux Uusing hwinfo Command?
|
||||
|
||||
**[hwinfo][1]** stands for hardware information tool is another great utility that used to probe for the hardware present in the system and display detailed information about varies hardware components in human readable format.
|
||||
|
||||
```
|
||||
# hwinfo --block | grep by-uuid | awk '{print $3,$7}'
|
||||
/dev/sdc1, /dev/disk/by-uuid/d17e3c31-e2c9-4f11-809c-94a549bc43b7
|
||||
/dev/sdc3, /dev/disk/by-uuid/ca307aa4-0866-49b1-8184-004025789e63
|
||||
/dev/sda1, /dev/disk/by-uuid/d92fa769-e00f-4fd7-b6ed-ecf7224af7fa
|
||||
```
|
||||
|
||||
### How To Check Disk Partition/FileSystem UUID In Linux Uusing udevadm Command?
|
||||
|
||||
udevadm expects a command and command specific options. It controls the runtime behavior of systemd-udevd, requests kernel events, manages the event queue, and provides simple debugging mechanisms.
|
||||
|
||||
```
|
||||
udevadm info -q all -n /dev/sdc1 | grep -i by-uuid | head -1
|
||||
S: disk/by-uuid/d17e3c31-e2c9-4f11-809c-94a549bc43b7
|
||||
```
|
||||
|
||||
### How To Check Disk Partition/FileSystem UUID In Linux Uusing tune2fs Command?
|
||||
|
||||
tune2fs allows the system administrator to adjust various tunable filesystem parameters on Linux ext2, ext3, or ext4 filesystems. The current values of these options can be displayed by using the -l option.
|
||||
|
||||
```
|
||||
# tune2fs -l /dev/sdc1 | grep UUID
|
||||
Filesystem UUID: d17e3c31-e2c9-4f11-809c-94a549bc43b7
|
||||
```
|
||||
|
||||
### How To Check Disk Partition/FileSystem UUID In Linux Uusing dumpe2fs Command?
|
||||
|
||||
dumpe2fs prints the super block and blocks group information for the filesystem present on device.
|
||||
|
||||
```
|
||||
# dumpe2fs /dev/sdc1 | grep UUID
|
||||
dumpe2fs 1.43.5 (04-Aug-2017)
|
||||
Filesystem UUID: d17e3c31-e2c9-4f11-809c-94a549bc43b7
|
||||
```
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.2daygeek.com/check-partitions-uuid-filesystem-uuid-universally-unique-identifier-linux/
|
||||
|
||||
作者：[Magesh Maruthamuthu][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[liujing97](https://github.com/liujing97)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://www.2daygeek.com/author/magesh/
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://www.2daygeek.com/hwinfo-check-display-detect-system-hardware-information-linux/
|
||||
@@ -1,91 +0,0 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (Enjoy Netflix? You Should Thank FreeBSD)
|
||||
[#]: via: (https://itsfoss.com/netflix-freebsd-cdn/)
|
||||
[#]: author: (Abhishek Prakash https://itsfoss.com/author/abhishek/)
|
||||
|
||||
Enjoy Netflix? You Should Thank FreeBSD
|
||||
======
|
||||
|
||||
Netflix is one of the most popular streaming services in the world.
|
||||
|
||||
But you already know that. Don’t you?
|
||||
|
||||
What you probably did not know is that Netflix uses [FreeBSD][1] to deliver its content to you.
|
||||
|
||||
Yes, that’s right. Netflix relies on FreeBSD to build its in-house content delivery network (CDN).
|
||||
|
||||
A [CDN][2] is a group of servers located in various part of the world. It is mainly used to deliver ‘heavy content’ like images and videos to the end-user faster than a centralized server.
|
||||
|
||||
Instead of opting for a commercial CDN service, Netflix has built its own in-house CDN called [Open Connect][3].
|
||||
|
||||
Open Connect utilizes [custom hardware][4], Open Connect Appliance. You can see it in the image below. It can handle 40Gb/s data and has a storage capacity of 248TB.
|
||||
|
||||
![Netflix’s Open Connect Appliance runs FreeBSD][5]
|
||||
|
||||
Netflix provides Open Connect Appliance to qualifying Internet Service Providers (ISP) for free. This way, substantial Netflix traffic gets localized and the ISPs deliver the Netflix content more efficiently.
|
||||
|
||||
This Open Connect Appliance runs on FreeBSD operating system and [almost exclusively runs open source software][6].
|
||||
|
||||
### Open Connect uses FreeBSD “Head”
|
||||
|
||||
![][7]
|
||||
|
||||
You would expect Netflix to use a stable release of FreeBSD for such a critical infrastructure but Netflix tracks the [FreeBSD head/current version][8]. Netflix says that tracking “head” lets them “stay forward-looking and focused on innovation”.
|
||||
|
||||
Here are the benefits Netflix sees of tracking FreeBSD:
|
||||
|
||||
* Quicker feature iteration
|
||||
* Quicker access to new FreeBSD features
|
||||
* Quicker bug fixes
|
||||
* Enables collaboration
|
||||
* Minimizes merge conflicts
|
||||
* Amortizes merge “cost”
|
||||
|
||||
|
||||
|
||||
> Running FreeBSD “head” lets us deliver large amounts of data to our users very efficiently, while maintaining a high velocity of feature development.
|
||||
>
|
||||
> Netflix
|
||||
|
||||
Remember, even [Google uses Debian][9] testing instead of Debian stable. Perhaps these enterprises prefer the cutting edge features more than anything else.
|
||||
|
||||
Like Google, Netflix also plans to upstream any code they can. This should help FreeBSD and other BSD distributions based on FreeBSD.
|
||||
|
||||
So what does Netflix achieves with FreeBSD? Here are some quick stats:
|
||||
|
||||
> Using FreeBSD and commodity parts, we achieve 90 Gb/s serving TLS-encrypted connections with ~55% CPU on a 16-core 2.6-GHz CPU.
|
||||
>
|
||||
> Netflix
|
||||
|
||||
If you want to know more about Netflix and FreeBSD, you can refer to [this presentation from FOSDEM][10]. You can also watch the video of the presentation [here][11].
|
||||
|
||||
These days big enterprises rely mostly on Linux for their server infrastructure but Netflix has put their trust in BSD. This is a good thing for BSD community because if an industry leader like Netflix throws its weight behind BSD, others could follow the lead. What do you think?
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://itsfoss.com/netflix-freebsd-cdn/
|
||||
|
||||
作者：[Abhishek Prakash][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://itsfoss.com/author/abhishek/
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://www.freebsd.org/
|
||||
[2]: https://www.cloudflare.com/learning/cdn/what-is-a-cdn/
|
||||
[3]: https://openconnect.netflix.com/en/
|
||||
[4]: https://openconnect.netflix.com/en/hardware/
|
||||
[5]: https://i2.wp.com/itsfoss.com/wp-content/uploads/2019/02/netflix-open-connect-appliance.jpeg?fit=800%2C533&ssl=1
|
||||
[6]: https://openconnect.netflix.com/en/software/
|
||||
[7]: https://i0.wp.com/itsfoss.com/wp-content/uploads/2019/02/netflix-freebsd.png?resize=800%2C450&ssl=1
|
||||
[8]: https://www.bsdnow.tv/tutorials/stable-current
|
||||
[9]: https://itsfoss.com/goobuntu-glinux-google/
|
||||
[10]: https://fosdem.org/2019/schedule/event/netflix_freebsd/attachments/slides/3103/export/events/attachments/netflix_freebsd/slides/3103/FOSDEM_2019_Netflix_and_FreeBSD.pdf
|
||||
[11]: http://mirror.onet.pl/pub/mirrors/video.fosdem.org/2019/Janson/netflix_freebsd.webm
|
||||
@@ -1,5 +1,5 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: (ustblixin)
|
||||
[#]: translator: ( )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
|
||||
@@ -1,74 +0,0 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: (geekpi)
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (Ubuntu 14.04 is Reaching the End of Life. Here are Your Options)
|
||||
[#]: via: (https://itsfoss.com/ubuntu-14-04-end-of-life/)
|
||||
[#]: author: (Abhishek Prakash https://itsfoss.com/author/abhishek/)
|
||||
|
||||
Ubuntu 14.04 is Reaching the End of Life. Here are Your Options
|
||||
======
|
||||
|
||||
Ubuntu 14.04 is reaching its end of life on April 30, 2019. This means there will be no security and maintenance updates for Ubuntu 14.04 users beyond this date.
|
||||
|
||||
You won’t even get updates for installed applications and you won’t be able to install a new application using apt command or the Software Center without manually modifying the sources.list.
|
||||
|
||||
Ubuntu 14.04 was released almost five years ago. That’s the life of a long term support release of Ubuntu.
|
||||
|
||||
[Check Ubuntu version][1] and see if you are still using Ubuntu 14.04. If that’s the case either on desktops or on servers, you might be wondering what should you do in such a situation.
|
||||
|
||||
Let me help you out there. Let me tell you what options do you have in this case.
|
||||
|
||||
![][2]
|
||||
|
||||
### Upgrade to Ubuntu 16.04 LTS (easiest of them all)
|
||||
|
||||
If you have a good internet connection, you can upgrade to Ubuntu 16.04 LTS from within Ubuntu 14.04.
|
||||
|
||||
Ubuntu 16.04 is also a long term support release and it will be supported till April, 2021. Which means you’ll have two years before another upgrade.
|
||||
|
||||
I recommend reading this tutorial about [upgrading Ubuntu version][3]. It was originally written for upgrading Ubuntu 16.04 to Ubuntu 18.04 but the steps are applicable in your case as well.
|
||||
|
||||
### Make a backup, do a fresh install of Ubuntu 18.04 LTS (ideal for desktop users)
|
||||
|
||||
The other option is that you make a backup of your Documents, Music, Pictures, Downloads and any other folder where you have kept essential data that you cannot afford to lose.
|
||||
|
||||
When I say backup, it simply means copying these folders to an external USB disk. In other words, you should have a way to copy the data back to your computer because you’ll be formatting your system.
|
||||
|
||||
I would recommend this option for the desktop users. Ubuntu 18.04 is the current long term support release and it will be supported till at least April, 2023. You have four long years before you are forced for another upgrade.
|
||||
|
||||
### Pay for extended security maintenance and continue using Ubuntu 14.04
|
||||
|
||||
This is suited for enterprise/corporate clients. Canonical, the parent company of Ubuntu, provides the Ubuntu Advantage program where customers can pay for phone/email based support among other benefits.
|
||||
|
||||
Ubuntu Advantage program users also have the [Extended Security Maintenance][4] (ESM) feature. This program provides security updates even after reaching the end of life for a given version.
|
||||
|
||||
This comes at a cost. It costs $225 per year per physical node for server users. For desktop users, the price is $150 per year. You can read the detailed pricing of the Ubuntu Advantage program [here][5].
|
||||
|
||||
### Still using Ubuntu 14.04?
|
||||
|
||||
If you are still using Ubuntu 14.04, you should start exploring your options as you have less than two months to go.
|
||||
|
||||
In any case, you must not use Ubuntu 14.04 after 30 April 2019 because your system will be vulnerable due to lack of security updates. Not being able to install new applications will be an additional major pain.
|
||||
|
||||
So, what option do you choose here? Upgrading to Ubuntu 16.04 or 18.04 or paying for the ESM?
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://itsfoss.com/ubuntu-14-04-end-of-life/
|
||||
|
||||
作者：[Abhishek Prakash][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://itsfoss.com/author/abhishek/
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://itsfoss.com/how-to-know-ubuntu-unity-version/
|
||||
[2]: https://i1.wp.com/itsfoss.com/wp-content/uploads/2019/02/ubuntu-14-04-end-of-life-featured.png?resize=800%2C450&ssl=1
|
||||
[3]: https://itsfoss.com/upgrade-ubuntu-version/
|
||||
[4]: https://www.ubuntu.com/esm
|
||||
[5]: https://www.ubuntu.com/support/plans-and-pricing
|
||||
@@ -1,301 +0,0 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: (liujing97)
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (How To Configure sudo Access In Linux?)
|
||||
[#]: via: (https://www.2daygeek.com/how-to-configure-sudo-access-in-linux/)
|
||||
[#]: author: (Magesh Maruthamuthu https://www.2daygeek.com/author/magesh/)
|
||||
|
||||
How To Configure sudo Access In Linux?
|
||||
======
|
||||
|
||||
The root user has all the controls in Linux system.
|
||||
|
||||
root user is the most powerful user in the Linux system and can perform any action in the system.
|
||||
|
||||
If any users wants to perform some actions, don’t provide the root access to anybody because if he/she done anything wrong there is no option/way to rectify it.
|
||||
|
||||
To fix this, what will be the solution?
|
||||
|
||||
We can grant sudo permission to the corresponding user to overcome this situation.
|
||||
|
||||
The sudo command offers a mechanism for providing trusted users with administrative access to a system without sharing the password of the root user.
|
||||
|
||||
They can perform most of the administrative operations but not all operations like root.
|
||||
|
||||
### What Is sudo?
|
||||
|
||||
sudo is a program, which can be used by a normal users to execute a command as the super user or another user, as specified by the security policy.
|
||||
|
||||
sudo users access is controlled by `/etc/sudoers` file.
|
||||
|
||||
### What Is An Advantage Of sudo Users?
|
||||
|
||||
sudo is a safe way to run a command in Linux system if you are not familiar on it.
|
||||
|
||||
* The Linux system keeps a logs into the `/var/log/secure` and `/var/log/auth.log` file where you can verify what actions was made by the sudo user.
|
||||
* Every time, it will prompt a password to perform the current action. So, you will be getting a time to verify the action, which you are going to perform. If you feel it’s not a correct action then you can safely exit there itself without perform the current action.
|
||||
|
||||
|
||||
|
||||
It’s different for RHEL based systems such as Redhat (RHEL), CentOS and Oracle Enterprise Linux (OEL) and Debian based systems such as Debian, Ubuntu and LinuxMint.
|
||||
|
||||
We will tech you, how to perform this on both the distributions in this article.
|
||||
|
||||
It can be done in three ways in both the distributions.
|
||||
|
||||
* Add a user into corresponding groups. For RHEL based system, we need to add a user into `wheel` group. For Debian based system, we need to add a user into `sudo` or `admin` groups.
|
||||
* Add a user into `/etc/group` file manually.
|
||||
* Add a user into `/etc/sudoers` file using visudo.
|
||||
|
||||
|
||||
|
||||
### How To Configure sudo Access In RHEL/CentOS/OEL Systems?
|
||||
|
||||
It can be done on RHEL based systems such as Redhat (RHEL), CentOS and Oracle Enterprise Linux (OEL) using following three methods.
|
||||
|
||||
### Method-1: How To Grant The Super User Access To A Normal User In Linux Using wheel Group?
|
||||
|
||||
Wheel is a special group in the RHEL based systems that provides additional privileges that empower a user to execute restricted commands as the super user.
|
||||
|
||||
Make a note that the `wheel` group should be enabled in the `/etc/sudoers` file to gain this access.
|
||||
|
||||
```
|
||||
# grep -i wheel /etc/sudoers
|
||||
|
||||
## Allows people in group wheel to run all commands
|
||||
%wheel ALL=(ALL) ALL
|
||||
# %wheel ALL=(ALL) NOPASSWD: ALL
|
||||
```
|
||||
|
||||
I assume that we had already created an user account to perform this. In my case, I’m going to use `daygeek` user account.
|
||||
|
||||
Run the following command to add an user into wheel group.
|
||||
|
||||
```
|
||||
# usermod -aG wheel daygeek
|
||||
```
|
||||
|
||||
We can doube confirm this by running the following command.
|
||||
|
||||
```
|
||||
# getent group wheel
|
||||
wheel:x:10:daygeek
|
||||
```
|
||||
|
||||
I’m going to check whether `daygeek` user can access a file which is owned by the root user.
|
||||
|
||||
```
|
||||
$ tail -5 /var/log/secure
|
||||
tail: cannot open _/var/log/secure_ for reading: Permission denied
|
||||
```
|
||||
|
||||
I was getting an error when i try to access the `/var/log/secure` file as a normal user. I’m going to access the same file with sudo, let’s see the magic.
|
||||
|
||||
```
|
||||
$ sudo tail -5 /var/log/secure
|
||||
[sudo] password for daygeek:
|
||||
Mar 17 07:01:56 CentOS7 sudo: daygeek : TTY=pts/0 ; PWD=/home/daygeek ; USER=root ; COMMAND=/bin/tail -5 /var/log/secure
|
||||
Mar 17 07:01:56 CentOS7 sudo: pam_unix(sudo:session): session opened for user root by daygeek(uid=0)
|
||||
Mar 17 07:01:56 CentOS7 sudo: pam_unix(sudo:session): session closed for user root
|
||||
Mar 17 07:05:10 CentOS7 sudo: daygeek : TTY=pts/0 ; PWD=/home/daygeek ; USER=root ; COMMAND=/bin/tail -5 /var/log/secure
|
||||
Mar 17 07:05:10 CentOS7 sudo: pam_unix(sudo:session): session opened for user root by daygeek(uid=0)
|
||||
```
|
||||
|
||||
### Method-2: How To Grant The Super User Access To A Normal User In RHEL/CentOS/OEL using /etc/group file?
|
||||
|
||||
We can manually add an user into the wheel group by editing the `/etc/group` file.
|
||||
|
||||
Just open the file then append the corresponding user in the appropriate group to achieve this.
|
||||
|
||||
```
|
||||
$ grep -i wheel /etc/group
|
||||
wheel:x:10:daygeek,user1
|
||||
```
|
||||
|
||||
In this example, I’m going to use `user1` user account.
|
||||
|
||||
I’m going to check whether `user1` user has sudo access or not by restarting the `Apache` service in the system. let’s see the magic.
|
||||
|
||||
```
|
||||
$ sudo systemctl restart httpd
|
||||
[sudo] password for user1:
|
||||
|
||||
$ sudo grep -i user1 /var/log/secure
|
||||
[sudo] password for user1:
|
||||
Mar 17 07:09:47 CentOS7 sudo: user1 : TTY=pts/0 ; PWD=/home/user1 ; USER=root ; COMMAND=/bin/systemctl restart httpd
|
||||
Mar 17 07:10:40 CentOS7 sudo: user1 : TTY=pts/0 ; PWD=/home/user1 ; USER=root ; COMMAND=/bin/systemctl restart httpd
|
||||
Mar 17 07:12:35 CentOS7 sudo: user1 : TTY=pts/0 ; PWD=/home/user1 ; USER=root ; COMMAND=/bin/grep -i httpd /var/log/secure
|
||||
```
|
||||
|
||||
### Method-3: How To Grant The Super User Access To A Normal User In Linux Using /etc/sudoers file?
|
||||
|
||||
sudo users access is controlled by `/etc/sudoers` file. So, simply add an user into the sudoers file under wheel group.
|
||||
|
||||
Just append the desired user into /etc/suoders file by using visudo command.
|
||||
|
||||
```
|
||||
# grep -i user2 /etc/sudoers
|
||||
user2 ALL=(ALL) ALL
|
||||
```
|
||||
|
||||
In this example, I’m going to use `user2` user account.
|
||||
|
||||
I’m going to check whether `user2` user has sudo access or not by restarting the `MariaDB` service in the system. let’s see the magic.
|
||||
|
||||
```
|
||||
$ sudo systemctl restart mariadb
|
||||
[sudo] password for user2:
|
||||
|
||||
$ sudo grep -i mariadb /var/log/secure
|
||||
[sudo] password for user2:
|
||||
Mar 17 07:23:10 CentOS7 sudo: user2 : TTY=pts/0 ; PWD=/home/user2 ; USER=root ; COMMAND=/bin/systemctl restart mariadb
|
||||
Mar 17 07:26:52 CentOS7 sudo: user2 : TTY=pts/0 ; PWD=/home/user2 ; USER=root ; COMMAND=/bin/grep -i mariadb /var/log/secure
|
||||
```
|
||||
|
||||
### How To Configure sudo Access In Debian/Ubuntu Systems?
|
||||
|
||||
It can be done on Debian based systems such as Debian based systems such as Debian, Ubuntu and LinuxMint using following three methods.
|
||||
|
||||
### Method-1: How To Grant The Super User Access To A Normal User In Linux Using sudo or admin Groups?
|
||||
|
||||
sudo or admin is a special group in the Debian based systems that provides additional privileges that empower a user to execute restricted commands as the super user.
|
||||
|
||||
Make a note that the `sudo` or `admin` group should be enabled in the `/etc/sudoers` file to gain this access.
|
||||
|
||||
```
|
||||
# grep -i 'sudo\|admin' /etc/sudoers
|
||||
|
||||
# Members of the admin group may gain root privileges
|
||||
%admin ALL=(ALL) ALL
|
||||
|
||||
# Allow members of group sudo to execute any command
|
||||
%sudo ALL=(ALL:ALL) ALL
|
||||
```
|
||||
|
||||
I assume that we had already created an user account to perform this. In my case, I’m going to use `2gadmin` user account.
|
||||
|
||||
Run the following command to add an user into sudo group.
|
||||
|
||||
```
|
||||
# usermod -aG sudo 2gadmin
|
||||
```
|
||||
|
||||
We can doube confirm this by running the following command.
|
||||
|
||||
```
|
||||
# getent group sudo
|
||||
sudo:x:27:2gadmin
|
||||
```
|
||||
|
||||
I’m going to check whether `2gadmin` user can access a file which is owned by the root user.
|
||||
|
||||
```
|
||||
$ less /var/log/auth.log
|
||||
/var/log/auth.log: Permission denied
|
||||
```
|
||||
|
||||
I was getting an error when i try to access the `/var/log/auth.log` file as a normal user. I’m going to access the same file with sudo, let’s see the magic.
|
||||
|
||||
```
|
||||
$ sudo tail -5 /var/log/auth.log
|
||||
[sudo] password for 2gadmin:
|
||||
Mar 17 20:39:47 Ubuntu18 sudo: 2gadmin : TTY=pts/0 ; PWD=/home/2gadmin ; USER=root ; COMMAND=/bin/bash
|
||||
Mar 17 20:39:47 Ubuntu18 sudo: pam_unix(sudo:session): session opened for user root by 2gadmin(uid=0)
|
||||
Mar 17 20:40:23 Ubuntu18 sudo: pam_unix(sudo:session): session closed for user root
|
||||
Mar 17 20:40:48 Ubuntu18 sudo: 2gadmin : TTY=pts/0 ; PWD=/home/2gadmin ; USER=root ; COMMAND=/usr/bin/tail -5 /var/log/auth.log
|
||||
Mar 17 20:40:48 Ubuntu18 sudo: pam_unix(sudo:session): session opened for user root by 2gadmin(uid=0)
|
||||
```
|
||||
|
||||
Alternatively we can perform the same by adding an user to `admin` group.
|
||||
|
||||
Run the following command to add an user into sudo group.
|
||||
|
||||
```
|
||||
# usermod -aG admin user1
|
||||
```
|
||||
|
||||
We can doube confirm this by running the following command.
|
||||
|
||||
```
|
||||
# getent group admin
|
||||
admin:x:1011:user1
|
||||
```
|
||||
|
||||
Let’s see the output.
|
||||
|
||||
```
|
||||
$ sudo tail -2 /var/log/auth.log
|
||||
[sudo] password for user1:
|
||||
Mar 17 20:53:36 Ubuntu18 sudo: user1 : TTY=pts/0 ; PWD=/home/user1 ; USER=root ; COMMAND=/usr/bin/tail -2 /var/log/auth.log
|
||||
Mar 17 20:53:36 Ubuntu18 sudo: pam_unix(sudo:session): session opened for user root by user1(uid=0)
|
||||
```
|
||||
|
||||
### Method-2: How To Grant The Super User Access To A Normal User In Debian/Ubuntu using /etc/group file?
|
||||
|
||||
We can manually add an user into the sudo or admin group by editing the `/etc/group` file.
|
||||
|
||||
Just open the file then append the corresponding user in the appropriate group to achieve this.
|
||||
|
||||
```
|
||||
$ grep -i sudo /etc/group
|
||||
sudo:x:27:2gadmin,user2
|
||||
```
|
||||
|
||||
In this example, I’m going to use `user2` user account.
|
||||
|
||||
I’m going to check whether `user2` user has sudo access or not by restarting the `Apache` service in the system. let’s see the magic.
|
||||
|
||||
```
|
||||
$ sudo systemctl restart apache2
|
||||
[sudo] password for user2:
|
||||
|
||||
$ sudo tail -f /var/log/auth.log
|
||||
[sudo] password for user2:
|
||||
Mar 17 21:01:04 Ubuntu18 systemd-logind[559]: New session 22 of user user2.
|
||||
Mar 17 21:01:04 Ubuntu18 systemd: pam_unix(systemd-user:session): session opened for user user2 by (uid=0)
|
||||
Mar 17 21:01:33 Ubuntu18 sudo: user2 : TTY=pts/0 ; PWD=/home/user2 ; USER=root ; COMMAND=/bin/systemctl restart apache2
|
||||
```
|
||||
|
||||
### Method-3: How To Grant The Super User Access To A Normal User In Linux Using /etc/sudoers file?
|
||||
|
||||
sudo users access is controlled by `/etc/sudoers` file. So, simply add an user into the sudoers file under sudo or admin group.
|
||||
|
||||
Just append the desired user into /etc/suoders file by using visudo command.
|
||||
|
||||
```
|
||||
# grep -i user3 /etc/sudoers
|
||||
user3 ALL=(ALL:ALL) ALL
|
||||
```
|
||||
|
||||
In this example, I’m going to use `user3` user account.
|
||||
|
||||
I’m going to check whether `user3` user has sudo access or not by restarting the `MariaDB` service in the system. let’s see the magic.
|
||||
|
||||
```
|
||||
$ sudo systemctl restart mariadb
|
||||
[sudo] password for user3:
|
||||
|
||||
$ sudo tail -f /var/log/auth.log
|
||||
[sudo] password for user3:
|
||||
Mar 17 21:12:32 Ubuntu18 systemd-logind[559]: New session 24 of user user3.
|
||||
Mar 17 21:12:49 Ubuntu18 sudo: user3 : TTY=pts/0 ; PWD=/home/user3 ; USER=root ; COMMAND=/bin/systemctl restart mariadb
|
||||
Mar 17 21:12:49 Ubuntu18 sudo: pam_unix(sudo:session): session opened for user root by user3(uid=0)
|
||||
Mar 17 21:12:53 Ubuntu18 sudo: pam_unix(sudo:session): session closed for user root
|
||||
Mar 17 21:13:08 Ubuntu18 sudo: user3 : TTY=pts/0 ; PWD=/home/user3 ; USER=root ; COMMAND=/usr/bin/tail -f /var/log/auth.log
|
||||
Mar 17 21:13:08 Ubuntu18 sudo: pam_unix(sudo:session): session opened for user root by user3(uid=0)
|
||||
```
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.2daygeek.com/how-to-configure-sudo-access-in-linux/
|
||||
|
||||
作者：[Magesh Maruthamuthu][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[liujing97](https://github.com/liujing97)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://www.2daygeek.com/author/magesh/
|
||||
[b]: https://github.com/lujun9972
|
||||
@@ -1,188 +0,0 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (How To Check If A Port Is Open On Multiple Remote Linux System Using Shell Script With nc Command?)
|
||||
[#]: via: (https://www.2daygeek.com/check-a-open-port-on-multiple-remote-linux-server-using-nc-command/)
|
||||
[#]: author: (Magesh Maruthamuthu https://www.2daygeek.com/author/magesh/)
|
||||
|
||||
How To Check If A Port Is Open On Multiple Remote Linux System Using Shell Script With nc Command?
|
||||
======
|
||||
|
||||
We had recently written an article to check if a port is open on the remote Linux server. It will help you to check for single server.
|
||||
|
||||
If you want to check for five servers then no issues, you can use any of the one following command such as nc (netcat), nmap and telnet.
|
||||
|
||||
If you would like to check for 50+ servers then what will be the solution?
|
||||
|
||||
It’s not easy to check all servers, if you do the same then there is no point and you will be wasting a lots of time unnecessarily.
|
||||
|
||||
To overcome this situation, i had coded a small shell script using nc command that will allow us to scan any number of servers with given port.
|
||||
|
||||
If you are looking for a single server scan then you have multiple options, to know more about it. Simply navigate to the following URL to **[Check Whether A Port Is Open On The Remote Linux System?][1]**
|
||||
|
||||
There are two scripts available in this tutorial and both the scripts are useful.
|
||||
|
||||
Both scripts are used for different purpose, which you can easily understand by reading a head line.
|
||||
|
||||
I will ask you few questions before you are reading this article, just answer yourself if you know or you can get it by reading this article.
|
||||
|
||||
How to check, if a port is open on the remote Linux server?
|
||||
|
||||
How to check, if a port is open on the multiple remote Linux server?
|
||||
|
||||
How to check, if multiple ports are open on the multiple remote Linux server?
|
||||
|
||||
### What Is nc (netcat) Command?
|
||||
|
||||
nc stands for netcat. Netcat is a simple Unix utility which reads and writes data across network connections, using TCP or UDP protocol.
|
||||
|
||||
It is designed to be a reliable “back-end” tool that can be used directly or easily driven by other programs and scripts.
|
||||
|
||||
At the same time, it is a feature-rich network debugging and exploration tool, since it can create almost any kind of connection you would need and has several interesting built-in capabilities.
|
||||
|
||||
Netcat has three main modes of functionality. These are the connect mode, the listen mode, and the tunnel mode.
|
||||
|
||||
**Common Syntax for nc (netcat):**
|
||||
|
||||
```
|
||||
$ nc [-options] [HostName or IP] [PortNumber]
|
||||
```
|
||||
|
||||
### How To Check If A Port Is Open On Multiple Remote Linux Server?
|
||||
|
||||
Use the following shell script if you would like to check the given port is open on multiple remote Linux servers or not.
|
||||
|
||||
In my case, we are going to check whether the port 22 is open in the following remote servers or not? Make sure you have to update your servers list in the file instead of us.
|
||||
|
||||
Make sure you have to update the servers list into `server-list.txt file`. Each server should be in separate line.
|
||||
|
||||
```
|
||||
# cat server-list.txt
|
||||
192.168.1.2
|
||||
192.168.1.3
|
||||
192.168.1.4
|
||||
192.168.1.5
|
||||
192.168.1.6
|
||||
192.168.1.7
|
||||
```
|
||||
|
||||
Use the following script to achieve this.
|
||||
|
||||
```
|
||||
# vi port_scan.sh
|
||||
|
||||
#!/bin/sh
|
||||
for server in `more server-list.txt`
|
||||
do
|
||||
#echo $i
|
||||
nc -zvw3 $server 22
|
||||
done
|
||||
```
|
||||
|
||||
Set an executable permission to `port_scan.sh` file.
|
||||
|
||||
```
|
||||
$ chmod +x port_scan.sh
|
||||
```
|
||||
|
||||
Finally run the script to achieve this.
|
||||
|
||||
```
|
||||
# sh port_scan.sh
|
||||
|
||||
Connection to 192.168.1.2 22 port [tcp/ssh] succeeded!
|
||||
Connection to 192.168.1.3 22 port [tcp/ssh] succeeded!
|
||||
Connection to 192.168.1.4 22 port [tcp/ssh] succeeded!
|
||||
Connection to 192.168.1.5 22 port [tcp/ssh] succeeded!
|
||||
Connection to 192.168.1.6 22 port [tcp/ssh] succeeded!
|
||||
Connection to 192.168.1.7 22 port [tcp/ssh] succeeded!
|
||||
```
|
||||
|
||||
### How To Check If Multiple Ports Are Open On Multiple Remote Linux Server?
|
||||
|
||||
Use the following script if you want to check the multiple ports in multiple servers.
|
||||
|
||||
In my case, we are going to check whether the port 22 and 80 is open or not in the given servers. Make sure you have to replace your required ports and servers name instead of us.
|
||||
|
||||
Make sure you have to update the port lists into `port-list.txt` file. Each port should be in a separate line.
|
||||
|
||||
```
|
||||
# cat port-list.txt
|
||||
22
|
||||
80
|
||||
```
|
||||
|
||||
Make sure you have to update the servers list into `server-list.txt` file. Each server should be in separate line.
|
||||
|
||||
```
|
||||
# cat server-list.txt
|
||||
192.168.1.2
|
||||
192.168.1.3
|
||||
192.168.1.4
|
||||
192.168.1.5
|
||||
192.168.1.6
|
||||
192.168.1.7
|
||||
```
|
||||
|
||||
Use the following script to achieve this.
|
||||
|
||||
```
|
||||
# vi multiple_port_scan.sh
|
||||
|
||||
#!/bin/sh
|
||||
for server in `more server-list.txt`
|
||||
do
|
||||
for port in `more port-list.txt`
|
||||
do
|
||||
#echo $server
|
||||
nc -zvw3 $server $port
|
||||
echo ""
|
||||
done
|
||||
done
|
||||
```
|
||||
|
||||
Set an executable permission to `multiple_port_scan.sh` file.
|
||||
|
||||
```
|
||||
$ chmod +x multiple_port_scan.sh
|
||||
```
|
||||
|
||||
Finally run the script to achieve this.
|
||||
|
||||
```
|
||||
# sh multiple_port_scan.sh
|
||||
Connection to 192.168.1.2 22 port [tcp/ssh] succeeded!
|
||||
Connection to 192.168.1.2 80 port [tcp/http] succeeded!
|
||||
|
||||
Connection to 192.168.1.3 22 port [tcp/ssh] succeeded!
|
||||
Connection to 192.168.1.3 80 port [tcp/http] succeeded!
|
||||
|
||||
Connection to 192.168.1.4 22 port [tcp/ssh] succeeded!
|
||||
Connection to 192.168.1.4 80 port [tcp/http] succeeded!
|
||||
|
||||
Connection to 192.168.1.5 22 port [tcp/ssh] succeeded!
|
||||
Connection to 192.168.1.5 80 port [tcp/http] succeeded!
|
||||
|
||||
Connection to 192.168.1.6 22 port [tcp/ssh] succeeded!
|
||||
Connection to 192.168.1.6 80 port [tcp/http] succeeded!
|
||||
|
||||
Connection to 192.168.1.7 22 port [tcp/ssh] succeeded!
|
||||
Connection to 192.168.1.7 80 port [tcp/http] succeeded!
|
||||
```
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.2daygeek.com/check-a-open-port-on-multiple-remote-linux-server-using-nc-command/
|
||||
|
||||
作者：[Magesh Maruthamuthu][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://www.2daygeek.com/author/magesh/
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://www.2daygeek.com/how-to-check-whether-a-port-is-open-on-the-remote-linux-system-server/
|
||||
@@ -1,222 +0,0 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: (Modrisco)
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (Getting started with Vim: The basics)
|
||||
[#]: via: (https://opensource.com/article/19/3/getting-started-vim)
|
||||
[#]: author: (Bryant Son (Red Hat, Community Moderator) https://opensource.com/users/brson)
|
||||
|
||||
Getting started with Vim: The basics
|
||||
======
|
||||
|
||||
Learn to use Vim enough to get by at work or for a new project.
|
||||
|
||||
![Person standing in front of a giant computer screen with numbers, data][1]
|
||||
|
||||
I remember the very first time I encountered Vim. I was a university student, and the computers in the computer science department's lab were installed with Ubuntu Linux. While I had been exposed to different Linux variations (like RHEL) even before my college years (Red Hat sold its CDs at Best Buy!), this was the first time I needed to use the Linux operating system regularly, because my classes required me to do so. Once I started using Linux, like many others before and after me, I began to feel like a "real programmer."
|
||||
|
||||
![Real Programmers comic][2]
|
||||
|
||||
Real Programmers, by [xkcd][3]
|
||||
|
||||
Students could use a graphical text editor like [Kate][4], which was installed on the lab computers by default. For students who could use the shell but weren't used to the console-based editor, the popular choice was [Nano][5], which provided good interactive menus and an experience similar to Windows' graphical text editor.
|
||||
|
||||
I used Nano sometimes, but I heard awesome things about [Vi/Vim][6] and [Emacs][7] and really wanted to give them a try (mainly because they looked cool, and I was also curious to see what was so great about them). Using Vim for the first time scared me—I did not want to mess anything up! But once I got the hang of it, things became much easier and I could appreciate the editor's powerful capabilities. As for Emacs, well, I sort of gave up, but I'm happy I stuck with Vim.
|
||||
|
||||
In this article, I will walk through Vim (based on my personal experience) just enough so you can get by with it as an editor on a Linux system. This will neither make you an expert nor even scratch the surface of many of Vim's powerful capabilities. But the starting point always matters, and I want to make the beginning experience as easy as possible, and you can explore the rest on your own.
|
||||
|
||||
### Step 0: Open a console window
|
||||
|
||||
Before jumping into Vim, you need to do a little preparation. Open a console terminal from your Linux operating system. (Since Vim is also available on MacOS, Mac users can use these instructions, also.)
|
||||
|
||||
Once a terminal window is up, type the **ls** command to list the current directory. Then, type **mkdir Tutorial** to create a new directory called **Tutorial**. Go inside the directory by typing **cd Tutorial**.
|
||||
|
||||
![Create a folder][8]
|
||||
|
||||
That's it for preparation. Now it's time to move on to the fun part—starting to use Vim.
|
||||
|
||||
### Step 1: Create and close a Vim file without saving
|
||||
|
||||
Remember when I said I was scared to use Vim at first? Well, the scary part was thinking, "what if I change an existing file and mess things up?" After all, several computer science assignments required me to work on existing files by modifying them. I wanted to know: _How can I open and close a file without saving my changes?_
|
||||
|
||||
The good news is you can use the same command to create or open a file in Vim: **vim <FILE_NAME**>, where **< FILE_NAME>** represents the target file name you want to create or modify. Let's create a file named **HelloWorld.java** by typing **vim HelloWorld.java**.
|
||||
|
||||
Hello, Vim! Now, here is a very important concept in Vim, possibly the most important to remember: Vim has multiple modes. Here are three you need to know to do Vim basics:
|
||||
|
||||
Mode | Description
|
||||
---|---
|
||||
Normal | Default; for navigation and simple editing
|
||||
Insert | For explicitly inserting and modifying text
|
||||
Command Line | For operations like saving, exiting, etc.
|
||||
|
||||
Vim has other modes, like Visual, Select, and Ex-Mode, but Normal, Insert, and Command Line modes are good enough for us.
|
||||
|
||||
You are now in Normal mode. If you have text, you can move around with your arrow keys or other navigation keystrokes (which you will see later). To make sure you are in Normal mode, simply hit the **Esc** (Escape) key.
|
||||
|
||||
> **Tip:** **Esc** switches to Normal mode. Even though you are already in Normal mode, hit **Esc** just for practice's sake.
|
||||
|
||||
Now, this will be interesting. Press **:** (the colon key) followed by **q!** (i.e., **:q!** ). Your screen will look like this:
|
||||
|
||||
![Editing Vim][9]
|
||||
|
||||
Pressing the colon in Normal mode switches Vim to Command Line mode, and the **:q!** command quits the Vim editor without saving. In other words, you are abandoning all changes. You can also use **ZQ** ; choose whichever option is more convenient.
|
||||
|
||||
Once you hit **Enter** , you should no longer be in Vim. Repeat the exercise a few times, just to get the hang of it. Once you've done that, move on to the next section to learn how to make a change to this file.
|
||||
|
||||
### Step 2: Make and save modifications in Vim
|
||||
|
||||
Reopen the file by typing **vim HelloWorld.java** and pressing the **Enter** key. Insert mode is where you can make changes to a file. First, hit **Esc** to make sure you are in Normal mode, then press **i** to go into Insert mode. (Yes, that is the letter **i**.)
|
||||
|
||||
In the lower-left, you should see **\-- INSERT --**. This means you are in Insert mode.
|
||||
|
||||
![Vim insert mode][10]
|
||||
|
||||
Type some Java code. You can type anything you want, but here is an example for you to follow. Your screen will look like this:
|
||||
|
||||
|
||||
```
|
||||
public class HelloWorld {
|
||||
public static void main([String][11][] args) {
|
||||
}
|
||||
}
|
||||
```
|
||||
Very pretty! Notice how the text is highlighted in Java syntax highlight colors. Because you started the file in Java, Vim will detect the syntax color.
|
||||
|
||||
Save the file. Hit **Esc** to leave Insert mode and enter Command Line mode. Type **:** and follow that with **x!** (i.e., a colon followed by x and !). Hit **Enter** to save the file. You can also type **wq** to perform the same operation.
|
||||
|
||||
Now you know how to enter text using Insert mode and save the file using **:x!** or **:wq**.
|
||||
|
||||
### Step 3: Basic navigation in Vim
|
||||
|
||||
While you can always use your friendly Up, Down, Left, and Right arrow buttons to move around a file, that would be very difficult in a large file with almost countless lines. It's also helpful to be able to be able to jump around within a line. Although Vim has a ton of awesome navigation features, the first one I want to show you is how to go to a specific line.
|
||||
|
||||
Press the **Esc** key to make sure you are in Normal mode, then type **:set number** and hit **Enter** .
|
||||
|
||||
Voila! You see line numbers on the left side of each line.
|
||||
|
||||
![Showing Line Numbers][12]
|
||||
|
||||
OK, you may say, "that's cool, but how do I jump to a line?" Again, make sure you are in Normal mode, then press **: <LINE_NUMBER>**, where **< LINE_NUMBER>** is the number of the line you want to go to, and press **Enter**. Try moving to line 2.
|
||||
|
||||
```
|
||||
:2
|
||||
```
|
||||
|
||||
Now move to line 3.
|
||||
|
||||
![Jump to line 3][13]
|
||||
|
||||
But imagine a scenario where you are dealing with a file that is 1,000 lines long and you want to go to the end of the file. How do you get there? Make sure you are in Normal mode, then type **:$** and press **Enter**.
|
||||
|
||||
You will be on the last line!
|
||||
|
||||
Now that you know how to jump among the lines, as a bonus, let's learn how to move to the end of a line. Make sure you are on a line with some text, like line 3, and type **$**.
|
||||
|
||||
![Go to the last character][14]
|
||||
|
||||
You're now at the last character on the line. In this example, the open curly brace is highlighted to show where your cursor moved to, and the closing curly brace is highlighted because it is the opening curly brace's matching character.
|
||||
|
||||
That's it for basic navigation in Vim. Wait, don't exit the file, though. Let's move to basic editing in Vim. Feel free to grab a cup of coffee or tea, though.
|
||||
|
||||
### Step 4: Basic editing in Vim
|
||||
|
||||
Now that you know how to navigate around a file by hopping onto the line you want, you can use that skill to do some basic editing in Vim. Switch to Insert mode. (Remember how to do that, by hitting the **i** key?) Sure, you can edit by using the keyboard to delete or insert characters, but Vim offers much quicker ways to edit files.
|
||||
|
||||
Move to line 3, where it shows **public static void main(String[] args) {**. Quickly hit the **d** key twice in succession. Yes, that is **dd**. If you did it successfully, you will see a screen like this, where line 3 is gone, and every following line moved up by one (i.e., line 4 became line 3).
|
||||
|
||||
![Deleting A Line][15]
|
||||
|
||||
That's the _delete_ command. Don't fear! Hit **u** and you will see the deleted line recovered. Whew. This is the _undo_ command.
|
||||
|
||||
![Undoing a change in Vim][16]
|
||||
|
||||
The next lesson is learning how to copy and paste text, but first, you need to learn how to highlight text in Vim. Press **v** and move your Left and Right arrow buttons to select and deselect text. This feature is also very useful when you are showing code to others and want to identify the code you want them to see.
|
||||
|
||||
![Highlighting text in Vim][17]
|
||||
|
||||
Move to line 4, where it says **System.out.println("Hello, Opensource");**. Highlight all of line 4. Done? OK, while line 4 is still highlighted, press **y**. This is called _yank_ mode, and it will copy the text to the clipboard. Next, create a new line underneath by entering **o**. Note that this will put you into Insert mode. Get out of Insert mode by pressing **Esc** , then hit **p** , which stands for _paste_. This will paste the copied text from line 3 to line 4.
|
||||
|
||||
![Pasting in Vim][18]
|
||||
|
||||
As an exercise, repeat these steps but also modify the text on your newly created lines. Also, make sure the lines are aligned well.
|
||||
|
||||
> **Hint:** You need to switch back and forth between Insert mode and Command Line mode to accomplish this task.
|
||||
|
||||
Once you are finished, save the file with the **x!** command. That's all for basic editing in Vim.
|
||||
|
||||
### Step 5: Basic searching in Vim
|
||||
|
||||
Imagine your team lead wants you to change a text string in a project. How can you do that quickly? You might want to search for the line using a certain keyword.
|
||||
|
||||
Vim's search functionality can be very useful. Go into the Command Line mode by (1) pressing **Esc** key, then (2) pressing colon **:** ****key. We can search a keyword by entering : **/ <SEARCH_KEYWORD>**, where **< SEARCH_KEYWORD>** is the text string you want to find. Here we are searching for the keyword string "Hello." In the image below, the colon is missing but required.
|
||||
|
||||
![Searching in Vim][19]
|
||||
|
||||
However, a keyword can appear more than once, and this may not be the one you want. So, how do you navigate around to find the next match? You simply press the **n** key, which stands for _next_. Make sure that you aren't in Insert mode when you do this!
|
||||
|
||||
### Bonus step: Use split mode in Vim
|
||||
|
||||
That pretty much covers all the Vim basics. But, as a bonus, I want to show you a cool Vim feature called _split mode_.
|
||||
|
||||
Get out of _HelloWorld.java_ and create a new file. In a terminal window, type **vim GoodBye.java** and hit **Enter** to create a new file named _GoodBye.java_.
|
||||
|
||||
Enter any text you want; I decided to type "Goodbye." Save the file. (Remember you can use **:x!** or **:wq** in Command Line mode.)
|
||||
|
||||
In Command Line mode, type **:split HelloWorld.java** , and see what happens.
|
||||
|
||||
![Split mode in Vim][20]
|
||||
|
||||
Wow! Look at that! The **split** command created horizontally divided windows with _HelloWorld.java_ above and _GoodBye.java_ below. How can you switch between the windows? Hold **Control** (on a Mac) or **CTRL** (on a PC) then hit **ww** (i.e., **w** twice in succession).
|
||||
|
||||
As a final exercise, try to edit _GoodBye.java_ to match the screen below by copying and pasting from _HelloWorld.java_.
|
||||
|
||||
![Modify GoodBye.java file in Split Mode][21]
|
||||
|
||||
Save both files, and you are done!
|
||||
|
||||
> **TIP 1:** If you want to arrange the files vertically, use the command **:vsplit <FILE_NAME>** (instead of **:split <FILE_NAME>**, where **< FILE_NAME>** is the name of the file you want to open in Split mode.
|
||||
>
|
||||
> **TIP 2:** You can open more than two files by calling as many additional **split** or **vsplit** commands as you want. Try it and see how it looks.
|
||||
|
||||
### Vim cheat sheet
|
||||
|
||||
In this article, you learned how to use Vim just enough to get by for work or a project. But this is just the beginning of your journey to unlock Vim's powerful capabilities. Be sure to check out other great tutorials and tips on Opensource.com.
|
||||
|
||||
To make things a little easier, I've summarized everything you've learned into [a handy cheat sheet][22].
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/19/3/getting-started-vim
|
||||
|
||||
作者：[Bryant Son (Red Hat, Community Moderator)][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://opensource.com/users/brson
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/data_metrics_analytics_desktop_laptop.png?itok=9QXd7AUr (Person standing in front of a giant computer screen with numbers, data)
|
||||
[2]: https://opensource.com/sites/default/files/uploads/1_xkcdcartoon.jpg (Real Programmers comic)
|
||||
[3]: https://xkcd.com/378/
|
||||
[4]: https://kate-editor.org
|
||||
[5]: https://www.nano-editor.org
|
||||
[6]: https://www.vim.org
|
||||
[7]: https://www.gnu.org/software/emacs
|
||||
[8]: https://opensource.com/sites/default/files/uploads/2_createtestfolder.jpg (Create a folder)
|
||||
[9]: https://opensource.com/sites/default/files/uploads/4_existingvim.jpg (Editing Vim)
|
||||
[10]: https://opensource.com/sites/default/files/uploads/6_insertionmode.jpg (Vim insert mode)
|
||||
[11]: http://www.google.com/search?hl=en&q=allinurl%3Adocs.oracle.com+javase+docs+api+string
|
||||
[12]: https://opensource.com/sites/default/files/uploads/10_setnumberresult_0.jpg (Showing Line Numbers)
|
||||
[13]: https://opensource.com/sites/default/files/uploads/12_jumpintoline3.jpg (Jump to line 3)
|
||||
[14]: https://opensource.com/sites/default/files/uploads/14_gotolastcharacter.jpg (Go to the last character)
|
||||
[15]: https://opensource.com/sites/default/files/uploads/15_deletinglines.jpg (Deleting A Line)
|
||||
[16]: https://opensource.com/sites/default/files/uploads/16_undoingtheline.jpg (Undoing a change in Vim)
|
||||
[17]: https://opensource.com/sites/default/files/uploads/17_highlighting.jpg (Highlighting text in Vim)
|
||||
[18]: https://opensource.com/sites/default/files/uploads/19_pasting.jpg (Pasting in Vim)
|
||||
[19]: https://opensource.com/sites/default/files/uploads/22_searchmode.jpg (Searching in Vim)
|
||||
[20]: https://opensource.com/sites/default/files/uploads/26_copytonewfiles.jpg (Split mode in Vim)
|
||||
[21]: https://opensource.com/sites/default/files/uploads/27_exercise.jpg (Modify GoodBye.java file in Split Mode)
|
||||
[22]: https://opensource.com/downloads/cheat-sheet-vim
|
||||
@@ -1,154 +0,0 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: (HankChow)
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (Using Square Brackets in Bash: Part 1)
|
||||
[#]: via: (https://www.linux.com/blog/2019/3/using-square-brackets-bash-part-1)
|
||||
[#]: author: (Paul Brown https://www.linux.com/users/bro66)
|
||||
|
||||
Using Square Brackets in Bash: Part 1
|
||||
======
|
||||
|
||||
![square brackets][1]
|
||||
|
||||
This tutorial tackle square brackets and how they are used in different contexts at the command line.
|
||||
|
||||
[Creative Commons Zero][2]
|
||||
|
||||
After taking a look at [how curly braces (`{}`) work on the command line][3], now it’s time to tackle brackets (`[]`) and see how they are used in different contexts.
|
||||
|
||||
### Globbing
|
||||
|
||||
The first and easiest use of square brackets is in _globbing_. You have probably used globbing before without knowing it. Think of all the times you have listed files of a certain type, say, you wanted to list JPEGs, but not PNGs:
|
||||
|
||||
```
|
||||
ls *.jpg
|
||||
```
|
||||
|
||||
Using wildcards to get all the results that fit a certain pattern is precisely what we call globbing.
|
||||
|
||||
In the example above, the asterisk means " _zero or more characters_ ". There is another globbing wildcard, `?`, which means " _exactly one character_ ", so, while
|
||||
|
||||
```
|
||||
ls d*k*
|
||||
```
|
||||
|
||||
will list files called _darkly_ and _ducky_ (and _dark_ and _duck_ \-- remember `*` can also be zero characters),
|
||||
|
||||
```
|
||||
ls d*k?
|
||||
```
|
||||
|
||||
will not list _darkly_ (or _dark_ or _duck_ ), but it will list _ducky_.
|
||||
|
||||
Square brackets are used in globbing for sets of characters. To see what this means, make directory in which to carry out tests, `cd` into it and create a bunch of files like this:
|
||||
|
||||
```
|
||||
touch file0{0..9}{0..9}
|
||||
```
|
||||
|
||||
(If you don't know why that works, [take a look at the last installment that explains curly braces `{}`][3]).
|
||||
|
||||
This will create files _file000_ , _file001_ , _file002_ , etc., through _file097_ , _file098_ and _file099_.
|
||||
|
||||
Then, to list the files in the 70s and 80s, you can do this:
|
||||
|
||||
```
|
||||
ls file0[78]?
|
||||
```
|
||||
|
||||
To list _file022_ , _file027_ , _file028_ , _file052_ , _file057_ , _file058_ , _file092_ , _file097_ , and _file98_ you can do this:
|
||||
|
||||
```
|
||||
ls file0[259][278]
|
||||
```
|
||||
|
||||
Of course, you can use globbing (and square brackets for sets) for more than just `ls`. You can use globbing with any other tool for listing, removing, moving, or copying files, although the last two may require a bit of lateral thinking.
|
||||
|
||||
Let's say you want to create duplicates of files _file010_ through _file029_ and call the copies _archive010_ , _archive011_ , _archive012_ , etc..
|
||||
|
||||
You can't do:
|
||||
|
||||
```
|
||||
cp file0[12]? archive0[12]?
|
||||
```
|
||||
|
||||
Because globbing is for matching against existing files and directories and the _archive..._ files don't exist yet.
|
||||
|
||||
Doing this:
|
||||
|
||||
```
|
||||
cp file0[12]? archive0[1..2][0..9]
|
||||
```
|
||||
|
||||
won't work either, because `cp` doesn't let you copy many files to other many new files. Copying many files only works if you are copying them to a directory, so this:
|
||||
|
||||
```
|
||||
mkdir archive
|
||||
|
||||
cp file0[12]? archive
|
||||
```
|
||||
|
||||
would work, but it would copy the files, using their same names, into a directory called _archive/_. This is not what you set out to do.
|
||||
|
||||
However, if you look back at [the article on curly braces (`{}`)][3], you will remember how you can use `%` to lop off the end of a string contained in a variable.
|
||||
|
||||
Of course, there is a way you can also lop of the beginning of string contained in a variable. Instead of `%`, you use `#`.
|
||||
|
||||
For practice, you can try this:
|
||||
|
||||
```
|
||||
myvar="Hello World"
|
||||
|
||||
echo Goodbye Cruel ${myvar#Hello}
|
||||
```
|
||||
|
||||
It prints " _Goodbye Cruel World_ " because `#Hello` gets rid of the _Hello_ part at the beginning of the string stored in `myvar`.
|
||||
|
||||
You can use this feature alongside your globbing tools to make your _archive_ duplicates:
|
||||
|
||||
```
|
||||
for i in file0[12]?;\
|
||||
|
||||
do\
|
||||
|
||||
cp $i archive${i#file};\
|
||||
|
||||
done
|
||||
```
|
||||
|
||||
The first line tells the Bash interpreter that you want to loop through all the files that contain the string _file0_ followed by the digits _1_ or _2_ , and then one other character, which can be anything. The second line `do` indicates that what follows is the instruction or list of instructions you want the interpreter to loop through.
|
||||
|
||||
Line 3 is where the actually copying happens, and you use the contents of the loop variable _`i`_ **twice: First, straight out, as the first parameter of the `cp` command, and then you add _archive_ to its contents, while at the same time cutting of _file_. So, if _`i`_ contains, say, _file019_...
|
||||
|
||||
```
|
||||
"archive" + "file019" - "file" = "archive019"
|
||||
```
|
||||
|
||||
the `cp` line is expanded to this:
|
||||
|
||||
```
|
||||
cp file019 archive019
|
||||
```
|
||||
|
||||
Finally, notice how you can use the backslash `\` to split a chain of commands over several lines for clarity.
|
||||
|
||||
In part two, we’ll look at more ways to use square brackets. Stay tuned.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.linux.com/blog/2019/3/using-square-brackets-bash-part-1
|
||||
|
||||
作者：[Paul Brown][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://www.linux.com/users/bro66
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://www.linux.com/sites/lcom/files/styles/rendered_file/public/square-gabriele-diwald-475007-unsplash.jpg?itok=cKmysLfd (square brackets)
|
||||
[2]: https://www.linux.com/LICENSES/CATEGORY/CREATIVE-COMMONS-ZERO
|
||||
[3]: https://www.linux.com/blog/learn/2019/2/all-about-curly-braces-bash
|
||||
@@ -1,108 +0,0 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: (arrowfeng)
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (How to run PostgreSQL on Kubernetes)
|
||||
[#]: via: (https://opensource.com/article/19/3/how-run-postgresql-kubernetes)
|
||||
[#]: author: (Jonathan S. Katz https://opensource.com/users/jkatz05)
|
||||
|
||||
How to run PostgreSQL on Kubernetes
|
||||
======
|
||||
Create uniformly managed, cloud-native production deployments with the
|
||||
flexibility to deploy a personalized database-as-a-service.
|
||||
![cubes coming together to create a larger cube][1]
|
||||
|
||||
By running a [PostgreSQL][2] database on [Kubernetes][3], you can create uniformly managed, cloud-native production deployments with the flexibility to deploy a personalized database-as-a-service tailored to your specific needs.
|
||||
|
||||
Using an Operator allows you to provide additional context to Kubernetes to [manage a stateful application][4]. An Operator is also helpful when using an open source database like PostgreSQL to help with actions including provisioning, scaling, high availability, and user management.
|
||||
|
||||
Let's explore how to get PostgreSQL up and running on Kubernetes.
|
||||
|
||||
### Set up the PostgreSQL operator
|
||||
|
||||
The first step to using PostgreSQL with Kubernetes is installing an Operator. You can get up and running with the open source [Crunchy PostgreSQL Operator][5] on any Kubernetes-based environment with the help of Crunchy's [quickstart script][6] for Linux.
|
||||
|
||||
The quickstart script has a few prerequisites:
|
||||
|
||||
* The [Wget][7] utility installed
|
||||
* [kubectl][8] installed
|
||||
* A [StorageClass][9] defined on your Kubernetes cluster
|
||||
* Access to a Kubernetes user account with cluster-admin privileges. This is required to install the Operator [RBAC][10] rules
|
||||
* A [namespace][11] to hold the PostgreSQL Operator
|
||||
|
||||
|
||||
|
||||
Executing the script will give you a default PostgreSQL Operator deployment that assumes [dynamic storage][12] and a StorageClass named **standard**. User-provided values are allowed by the script to override these defaults.
|
||||
|
||||
You can download the quickstart script and set it to be executable with the following commands:
|
||||
|
||||
```
|
||||
wget <https://raw.githubusercontent.com/CrunchyData/postgres-operator/master/examples/quickstart.sh>
|
||||
chmod +x ./quickstart.sh
|
||||
```
|
||||
|
||||
Then you can execute the quickstart script:
|
||||
|
||||
```
|
||||
./examples/quickstart.sh
|
||||
```
|
||||
|
||||
After the script prompts you for some basic information about your Kubernetes cluster, it performs the following operations:
|
||||
|
||||
* Downloads the Operator configuration files
|
||||
* Sets the **$HOME/.pgouser** file to default settings
|
||||
* Deploys the Operator as a Kubernetes [Deployment][13]
|
||||
* Sets your **.bashrc** to include the Operator environmental variables
|
||||
* Sets your **$HOME/.bash_completion** file to be the **pgo bash_completion** file
|
||||
|
||||
|
||||
|
||||
During the quickstart's execution, you'll be prompted to set up the RBAC rules for your Kubernetes cluster. In a separate terminal, execute the command the quickstart command tells you to use.
|
||||
|
||||
Once the script completes, you'll get information on setting up a port forward to the PostgreSQL Operator pod. In a separate terminal, execute the port forward; this will allow you to begin executing commands to the PostgreSQL Operator! Try creating a cluster by entering:
|
||||
|
||||
```
|
||||
pgo create cluster mynewcluster
|
||||
```
|
||||
|
||||
You can test that your cluster is up and running with by entering:
|
||||
|
||||
```
|
||||
pgo test mynewcluster
|
||||
```
|
||||
|
||||
You can now manage your PostgreSQL databases in your Kubernetes environment! You can find a full reference to commands, including those for scaling, high availability, backups, and more, in the [documentation][14].
|
||||
|
||||
* * *
|
||||
|
||||
_Parts of this article are based on[Get Started Running PostgreSQL on Kubernetes][15] that the author wrote for the Crunchy blog._
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/19/3/how-run-postgresql-kubernetes
|
||||
|
||||
作者：[Jonathan S. Katz][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://opensource.com/users/jkatz05
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/cube_innovation_process_block_container.png?itok=vkPYmSRQ (cubes coming together to create a larger cube)
|
||||
[2]: https://www.postgresql.org/
|
||||
[3]: https://kubernetes.io/
|
||||
[4]: https://opensource.com/article/19/2/scaling-postgresql-kubernetes-operators
|
||||
[5]: https://github.com/CrunchyData/postgres-operator
|
||||
[6]: https://crunchydata.github.io/postgres-operator/stable/installation/#quickstart-script
|
||||
[7]: https://www.gnu.org/software/wget/
|
||||
[8]: https://kubernetes.io/docs/tasks/tools/install-kubectl/
|
||||
[9]: https://kubernetes.io/docs/concepts/storage/storage-classes/
|
||||
[10]: https://kubernetes.io/docs/reference/access-authn-authz/rbac/
|
||||
[11]: https://kubernetes.io/docs/concepts/overview/working-with-objects/namespaces/
|
||||
[12]: https://kubernetes.io/docs/concepts/storage/dynamic-provisioning/
|
||||
[13]: https://kubernetes.io/docs/concepts/workloads/controllers/deployment/
|
||||
[14]: https://crunchydata.github.io/postgres-operator/stable/#documentation
|
||||
[15]: https://info.crunchydata.com/blog/get-started-runnning-postgresql-on-kubernetes
|
||||
@@ -1,70 +0,0 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: (geekpi)
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (3 cool text-based email clients)
|
||||
[#]: via: (https://fedoramagazine.org/3-cool-text-based-email-clients/)
|
||||
[#]: author: (Clément Verna https://fedoramagazine.org/author/cverna/)
|
||||
|
||||
3 cool text-based email clients
|
||||
======
|
||||
|
||||
![][1]
|
||||
|
||||
Writing and receiving email is a big part of everyone’s daily routine and choosing an email client is usually a major decision. The Fedora OS provides a large choice of email clients and among these are text-based email applications.
|
||||
|
||||
### Mutt
|
||||
|
||||
Mutt is probably one of the most popular text-based email clients. It supports all the common features that one would expect from an email client. Color coding, mail threading, POP3, and IMAP are all supported by Mutt. But one of its best features is it’s highly configurable. Indeed, the user can easily change the keybindings, and create macros to adapt the tool to a particular workflow.
|
||||
|
||||
To give Mutt a try, install it [using sudo][2] and dnf:
|
||||
|
||||
```
|
||||
$ sudo dnf install mutt
|
||||
```
|
||||
|
||||
To help newcomers get started, Mutt has a very comprehensive [wiki][3] full of macro examples and configuration tricks.
|
||||
|
||||
### Alpine
|
||||
|
||||
Alpine is also among the most popular text-based email clients. It’s more beginner friendly than Mutt, and you can configure most of Alpine via the application itself — no need to edit a configuration file. One powerful feature of Alpine is the ability to score emails. This is particularly interesting for users that are registered to a high volume mailing list like Fedora’s [devel list][4]. Using scores, Alpine can sort the email based on the user’s interests, showing emails with a high score first.
|
||||
|
||||
Alpine is also available to install from Fedora’s repository using dnf.
|
||||
|
||||
```
|
||||
$ sudo dnf install alpine
|
||||
```
|
||||
|
||||
While using Alpine, you can easily access the documentation by pressing the _Ctrl+G_ key combination.
|
||||
|
||||
### nmh
|
||||
|
||||
nmh (new Mail Handling) follows the UNIX tools philosophy. It provides a collection of single purpose programs to send, receive, save, retrieve, and manipulate e-mail messages. This lets you swap the _nmh_ command with other programs, or create scripts around _nmh_ to create more customized tools. For example, you can use Mutt with nmh.
|
||||
|
||||
nmh can be easily installed using dnf.
|
||||
|
||||
```
|
||||
$ sudo dnf install nmh
|
||||
```
|
||||
|
||||
To learn more about nmh and mail handling in general you can read this GPL licenced [book][5].
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://fedoramagazine.org/3-cool-text-based-email-clients/
|
||||
|
||||
作者：[Clément Verna][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://fedoramagazine.org/author/cverna/
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://fedoramagazine.org/wp-content/uploads/2018/07/email-clients-816x345.png
|
||||
[2]: https://fedoramagazine.org/howto-use-sudo/
|
||||
[3]: https://gitlab.com/muttmua/mutt/wikis/home
|
||||
[4]: https://lists.fedoraproject.org/archives/list/devel@lists.fedoraproject.org/
|
||||
[5]: https://rand-mh.sourceforge.io/book/
|
||||
@@ -1,71 +0,0 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: (geekpi)
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (Parallel computation in Python with Dask)
|
||||
[#]: via: (https://opensource.com/article/19/4/parallel-computation-python-dask)
|
||||
[#]: author: (Moshe Zadka (Community Moderator) https://opensource.com/users/moshez)
|
||||
|
||||
Parallel computation in Python with Dask
|
||||
======
|
||||
The Dask library scales Python computation to multiple cores or even to
|
||||
multiple machines.
|
||||
![Pair programming][1]
|
||||
|
||||
One frequent complaint about Python performance is the [global interpreter lock][2] (GIL). Because of GIL, only one thread can execute Python byte code at a time. As a consequence, using threads does not speed up computation—even on modern, multi-core machines.
|
||||
|
||||
But when you need to parallelize to many cores, you don't need to stop using Python: the **[Dask][3]** library will scale computation to multiple cores or even to multiple machines. Some setups configure Dask on thousands of machines, each with multiple cores; while there are scaling limits, they are not easy to hit.
|
||||
|
||||
While Dask has many built-in array operations, as an example of something not built-in, we can calculate the [skewness][4]:
|
||||
```
|
||||
import numpy
|
||||
import dask
|
||||
from dask import array as darray
|
||||
|
||||
arr = dask.from_array(numpy.array(my_data), chunks=(1000,))
|
||||
mean = darray.mean()
|
||||
stddev = darray.std(arr)
|
||||
unnormalized_moment = darry.mean(arr * arr * arr)
|
||||
## See formula in wikipedia:
|
||||
skewness = ((unnormalized_moment - (3 * mean * stddev ** 2) - mean ** 3) /
|
||||
stddev ** 3)
|
||||
```
|
||||
|
||||
Notice that each operation will use as many cores as needed. This will parallelize across all cores, even when calculating across billions of elements.
|
||||
|
||||
Of course, it is not always the case that our operations can be parallelized by the library; sometimes we need to implement parallelism on our own.
|
||||
|
||||
For that, Dask has a "delayed" functionality:
|
||||
```
|
||||
import dask
|
||||
|
||||
def is_palindrome(s):
|
||||
return s == s[::-1]
|
||||
|
||||
palindromes = [dask.delayed(is_palindrome)(s) for s in string_list]
|
||||
total = dask.delayed(sum)(palindromes)
|
||||
result = total.compute()
|
||||
```
|
||||
|
||||
This will calculate whether strings are palindromes in parallel and will return a count of the palindromic ones.
|
||||
|
||||
While Dask was created for data scientists, it is by no means limited to data science. Whenever we need to parallelize tasks in Python, we can turn to Dask—GIL or no GIL.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/19/4/parallel-computation-python-dask
|
||||
|
||||
作者：[Moshe Zadka (Community Moderator)][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://opensource.com/users/moshez
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/collab-team-pair-programming-code-keyboard.png?itok=kBeRTFL1 (Pair programming)
|
||||
[2]: https://wiki.python.org/moin/GlobalInterpreterLock
|
||||
[3]: https://github.com/dask/dask
|
||||
[4]: https://en.wikipedia.org/wiki/Skewness#Definition
|
||||
@@ -1,168 +0,0 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (Using Square Brackets in Bash: Part 2)
|
||||
[#]: via: (https://www.linux.com/blog/learn/2019/4/using-square-brackets-bash-part-2)
|
||||
[#]: author: (Paul Brown https://www.linux.com/users/bro66)
|
||||
|
||||
Using Square Brackets in Bash: Part 2
|
||||
======
|
||||
|
||||
![square brackets][1]
|
||||
|
||||
We continue our tour of square brackets in Bash with a look at how they can act as a command.
|
||||
|
||||
[Creative Commons Zero][2]
|
||||
|
||||
Welcome back to our mini-series on square brackets. In the [previous article][3], we looked at various ways square brackets are used at the command line, including globbing. If you've not read that article, you might want to start there.
|
||||
|
||||
Square brackets can also be used as a command. Yep, for example, in:
|
||||
|
||||
```
|
||||
[ "a" = "a" ]
|
||||
```
|
||||
|
||||
which is, by the way, a valid command that you can execute, `[ ... ]` is a command. Notice that there are spaces between the opening bracket `[` and the parameters `"a" = "a"`, and then between the parameters and the closing bracket `]`. That is precisely because the brackets here act as a command, and you are separating the command from its parameters.
|
||||
|
||||
You would read the above line as " _test whether the string "a" is the same as string "a"_ ". If the premise is true, the `[ ... ]` command finishes with an exit status of 0. If not, the exit status is 1. [We talked about exit statuses in a previous article][4], and there you saw that you could access the value by checking the `$?` variable.
|
||||
|
||||
Try it out:
|
||||
|
||||
```
|
||||
[ "a" = "a" ]
|
||||
echo $?
|
||||
```
|
||||
|
||||
And now try:
|
||||
|
||||
```
|
||||
[ "a" = "b" ]
|
||||
echo $?
|
||||
```
|
||||
|
||||
In the first case, you will get a 0 (the premise is true), and running the second will give you a 1 (the premise is false). Remember that, in Bash, an exit status from a command that is 0 means it exited normally with no errors, and that makes it `true`. If there were any errors, the exit value would be a non-zero value (`false`). The `[ ... ]` command follows the same rules so that it is consistent with the rest of the other commands.
|
||||
|
||||
The `[ ... ]` command comes in handy in `if ... then` constructs and also in loops that require a certain condition to be met (or not) before exiting, like the `while` and `until` loops.
|
||||
|
||||
The logical operators for testing stuff are pretty straightforward:
|
||||
|
||||
```
|
||||
[ STRING1 = STRING2 ] => checks to see if the strings are equal
|
||||
[ STRING1 != STRING2 ] => checks to see if the strings are not equal
|
||||
[ INTEGER1 -eq INTEGER2 ] => checks to see if INTEGER1 is equal to INTEGER2
|
||||
[ INTEGER1 -ge INTEGER2 ] => checks to see if INTEGER1 is greater than or equal to INTEGER2
|
||||
[ INTEGER1 -gt INTEGER2 ] => checks to see if INTEGER1 is greater than INTEGER2
|
||||
[ INTEGER1 -le INTEGER2 ] => checks to see if INTEGER1 is less than or equal to INTEGER2
|
||||
[ INTEGER1 -lt INTEGER2 ] => checks to see if INTEGER1 is less than INTEGER2
|
||||
[ INTEGER1 -ne INTEGER2 ] => checks to see if INTEGER1 is not equal to INTEGER2
|
||||
etc...
|
||||
```
|
||||
|
||||
You can also test for some very shell-specific things. The `-f` option, for example, tests whether a file exists or not:
|
||||
|
||||
```
|
||||
for i in {000..099}; \
|
||||
do \
|
||||
if [ -f file$i ]; \
|
||||
then \
|
||||
echo file$i exists; \
|
||||
else \
|
||||
touch file$i; \
|
||||
echo I made file$i; \
|
||||
fi; \
|
||||
done
|
||||
```
|
||||
|
||||
If you run this in your test directory, line 3 will test to whether a file is in your long list of files. If it does exist, it will just print a message; but if it doesn't exist, it will create it, to make sure the whole set is complete.
|
||||
|
||||
You could write the loop more compactly like this:
|
||||
|
||||
```
|
||||
for i in {000..099};\
|
||||
do\
|
||||
if [ ! -f file$i ];\
|
||||
then\
|
||||
touch file$i;\
|
||||
echo I made file$i;\
|
||||
fi;\
|
||||
done
|
||||
```
|
||||
|
||||
The `!` modifier in the condition inverts the premise, thus line 3 would translate to " _if the file`file$i` does not exist_ ".
|
||||
|
||||
Try it: delete some random files from the bunch you have in your test directory. Then run the loop shown above and watch how it rebuilds the list.
|
||||
|
||||
There are plenty of other tests you can try, including `-d` tests to see if the name belongs to a directory and `-h` tests to see if it is a symbolic link. You can also test whether a files belongs to a certain group of users (`-G`), whether one file is older than another (`-ot`), or even whether a file contains something or is, on the other hand, empty.
|
||||
|
||||
Try the following for example. Add some content to some of your files:
|
||||
|
||||
```
|
||||
echo "Hello World" >> file023
|
||||
echo "This is a message" >> file065
|
||||
echo "To humanity" >> file010
|
||||
```
|
||||
|
||||
and then run this:
|
||||
|
||||
```
|
||||
for i in {000..099};\
|
||||
do\
|
||||
if [ ! -s file$i ];\
|
||||
then\
|
||||
rm file$i;\
|
||||
echo I removed file$i;\
|
||||
fi;\
|
||||
done
|
||||
```
|
||||
|
||||
And you'll remove all the files that are empty, leaving only the ones you added content to.
|
||||
|
||||
To find out more, check the manual page for the `test` command (a synonym for `[ ... ]`) with `man test`.
|
||||
|
||||
You may also see double brackets (`[[ ... ]]`) sometimes used in a similar way to single brackets. The reason for this is because double brackets give you a wider range of comparison operators. You can use `==`, for example, to compare a string to a pattern instead of just another string; or < and `>` to test whether a string would come before or after another in a dictionary.
|
||||
|
||||
To find out more about extended operators [check out this full list of Bash expressions][5].
|
||||
|
||||
### Next Time
|
||||
|
||||
In an upcoming article, we'll continue our tour and take a look at the role of parentheses `()` in Linux command lines. See you then!
|
||||
|
||||
_Read more:_
|
||||
|
||||
1. [The Meaning of Dot (`.`)][6]
|
||||
2. [Understanding Angle Brackets in Bash (`<...>`)][7]
|
||||
3. [More About Angle Brackets in Bash(`<` and `>`)][8]
|
||||
4. [And, Ampersand, and & in Linux (`&`)][9]
|
||||
5. [Ampersands and File Descriptors in Bash (`&`)][10]
|
||||
6. [Logical & in Bash (`&`)][4]
|
||||
7. [All about {Curly Braces} in Bash (`{}`)][11]
|
||||
8. [Using Square Brackets in Bash: Part 1][3]
|
||||
|
||||
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.linux.com/blog/learn/2019/4/using-square-brackets-bash-part-2
|
||||
|
||||
作者：[Paul Brown][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://www.linux.com/users/bro66
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://www.linux.com/sites/lcom/files/styles/rendered_file/public/square-brackets-3734552_1920.jpg?itok=hv9D6TBy (square brackets)
|
||||
[2]: /LICENSES/CATEGORY/CREATIVE-COMMONS-ZERO
|
||||
[3]: https://www.linux.com/blog/2019/3/using-square-brackets-bash-part-1
|
||||
[4]: https://www.linux.com/blog/learn/2019/2/logical-ampersand-bash
|
||||
[5]: https://www.gnu.org/software/bash/manual/bashref.html#Bash-Conditional-Expressions
|
||||
[6]: https://www.linux.com/blog/learn/2019/1/linux-tools-meaning-dot
|
||||
[7]: https://www.linux.com/blog/learn/2019/1/understanding-angle-brackets-bash
|
||||
[8]: https://www.linux.com/blog/learn/2019/1/more-about-angle-brackets-bash
|
||||
[9]: https://www.linux.com/blog/learn/2019/2/and-ampersand-and-linux
|
||||
[10]: https://www.linux.com/blog/learn/2019/2/ampersands-and-file-descriptors-bash
|
||||
[11]: https://www.linux.com/blog/learn/2019/2/all-about-curly-braces-bash
|
||||
@@ -1,86 +0,0 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: (tomjlw)
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (Streaming internet radio with RadioDroid)
|
||||
[#]: via: (https://opensource.com/article/19/4/radiodroid-internet-radio-player)
|
||||
[#]: author: (Chris Hermansen (Community Moderator) https://opensource.com/users/clhermansen)
|
||||
|
||||
Streaming internet radio with RadioDroid
|
||||
======
|
||||
Listen to your favorite internet radio stations over your home stereo
|
||||
with this easy setup.
|
||||
![woman programming][1]
|
||||
|
||||
Online news outlets have recently lamented the [passing of Google's Chromecast Audio device][2]. The device received [favorable reviews][3] in the audio press, so I had already been thinking about acquiring one. Given the news of Chromecast's demise, I decided to look for one at a reasonable price—before they were all snapped up or thrown in the dumpster.
|
||||
|
||||
I found one at [MobileFun][4] and put in my order. The device eventually arrived, packaged in the usual serviceable but minimal Google wrapping, with a very brief Get Started guide printed on the outside.
|
||||
|
||||
![Google Chromecast Audio][5]
|
||||
|
||||
I cabled it to my home stereo via my digital-analog converter's optical S/PDIF connection, hoping that would provide the best sound quality.
|
||||
|
||||
The setup ran flawlessly, and in about five minutes I was ready to play some tunes. I knew that a number of Android applications support Chromecast, so I decided to test it out with Google Play Music; sure enough, it worked just fine and sounded quite good. However, being an open source kind of person, I decided to see what I could find in the way of open source players that work with Chromecast.
|
||||
|
||||
### RadioDroid to the rescue
|
||||
|
||||
The [RadioDroid Android application][6] fit the bill. It is open source and available on [GitHub][7], Google Play, and [F-Droid][8]. According to the documentation, RadioDroid looks up and plays streams from the [Community Radio Browser][9] website. So I decided to install it on my handset and give it a shot.
|
||||
|
||||
![RadioDroid][10]
|
||||
|
||||
The installation was quick and smooth, and RadioDroid opened rapidly to display local stations. You can see the Chromecast button (the icon that looks like a rectangle with wavefronts) near the top-right side of this screenshot.
|
||||
|
||||
I played around with a few of the local stations. The application reliably played music on my handset's speaker, but I had to futz around with the Chromecast button to get the music to stream over the Chromecast. But stream it did!
|
||||
|
||||
I decided to seek out my favorite internet radio station, [Radio Grenouille][11] in Marseille, France. There are various ways to find stations in RadioDroid. One is to use the tabs—Local, Topclick, etc.—located above the list of stations. One of the tabs is Countries; I found France, with some 1,500 stations, on the list and scrolled—and scrolled, and scrolled—down through the list to find Radio Grenouille. Another way is to use the Search button at the top of the screen; the search was rapid and returned that wonderful radio station. I tried a few other searches, and they all returned reasonable info.
|
||||
|
||||
Going back to the Local tab, I scrolled through the listings and learned that "local" seems to be defined as "in the same country." So, even though Seattle, Portland, San Francisco, Los Angeles, and Juneau are closer to my home than Toronto, I didn't see any of them in Local. However, by using Search, I could find all stations with "Seattle" in their name.
|
||||
|
||||
The Languages tab let me find all stations broadcasting in Portugues, Portuguese, Português, Português Brasil, Português do Brasil, Portuguẽs, and Portugês. I quickly found another favorite station, [91 Rock Curitiba][12].
|
||||
|
||||
Then inspiration struck—it's springtime, but who cares? Let's listen to some Christmas music. And sure enough, searching for Christmas led me to [181.FM – Christmas Blender][13]. Well, a minute or two of that was enough for me…
|
||||
|
||||
So, all in all, I recommend the RadioDroid and Chromecast combo as a nice way to play internet radio on a home stereo at a reasonable cost.
|
||||
|
||||
### As for the music…
|
||||
|
||||
Recently I picked up an interesting album of very ambient (even beatless) music called [Continuum One][14] by [Qua Continuum][15] from the [Blue Coast Music][16] store. Blue Coast has a lot to offer the open source music enthusiast: music is available by download (and sometimes physical format) without resorting to those grotesque platform-specific download managers; it typically provides several formats, including WAV, FLAC, and DSD; different word lengths and bitrates are provided for WAV and FLAC, including 16/44.1, 24/96, and 24/192, and for DSD, 2.8, 5.6, and 11.2 MHz; and the music is recorded with great care using wonderful facilities. Unfortunately, I don't find a lot of music there to my taste, though I like a few of the artists available on Blue Coast, including Qua Continuum, [Art Lande][17], and [Alex De Grassi][18].
|
||||
|
||||
Over on [Bandcamp][19], I picked up [Emancipator's Baralku][20] and [Framework's Tides][21], both of which I enjoy. The music created by these two artists hits my sweet spot—it's electronic but not (generally) dance, it's melodic, and it tends to have some great hooks. There are many things for open source aficionados to like about Bandcamp, such as the ability to listen to the work in its entirety before buying; the lack of bloatware downloaders; the amounts shared with the musicians; and its support for [Creative Commons music][22].
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/19/4/radiodroid-internet-radio-player
|
||||
|
||||
作者：[Chris Hermansen (Community Moderator)][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[tomjlw](https://github.com/tomjlw)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://opensource.com/users/clhermansen
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/programming-code-keyboard-laptop-music-headphones.png?itok=EQZ2WKzy (woman programming)
|
||||
[2]: https://www.theverge.com/2019/1/11/18178751/google-chromecast-audio-discontinued-sale
|
||||
[3]: https://www.whathifi.com/google/chromecast-audio/review
|
||||
[4]: https://www.mobilefun.com/google-chromecast-audio-black-70476
|
||||
[5]: https://opensource.com/sites/default/files/uploads/internet-radio_chromecast.png (Google Chromecast Audio)
|
||||
[6]: https://play.google.com/store/apps/details?id=net.programmierecke.radiodroid2
|
||||
[7]: https://github.com/segler-alex/RadioDroid
|
||||
[8]: https://f-droid.org/en/packages/net.programmierecke.radiodroid2/
|
||||
[9]: http://www.radio-browser.info/gui/#!/
|
||||
[10]: https://opensource.com/sites/default/files/uploads/internet-radio_radiodroid.png (RadioDroid)
|
||||
[11]: http://www.radiogrenouille.com/
|
||||
[12]: https://91rock.com.br/
|
||||
[13]: http://player.181fm.com/?station=181-xblender
|
||||
[14]: https://www.youtube.com/watch?v=PqLCQXPS8iQ
|
||||
[15]: https://bluecoastmusic.com/artists/qua-continuum
|
||||
[16]: https://bluecoastmusic.com/store
|
||||
[17]: https://bluecoastmusic.com/store?f%5B0%5D=search_api_multi_aggregation_1%3Aart%20lande
|
||||
[18]: https://bluecoastmusic.com/store?f%5B0%5D=search_api_multi_aggregation_1%3Aalex%20de%20grassi
|
||||
[19]: https://bandcamp.com/
|
||||
[20]: https://emancipator.bandcamp.com/album/baralku
|
||||
[21]: https://frameworksuk.bandcamp.com/album/tides
|
||||
[22]: https://bandcamp.com/tag/creative-commons
|
||||
@@ -1,68 +0,0 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (Bash vs. Python: Which language should you use?)
|
||||
[#]: via: (https://opensource.com/article/19/4/bash-vs-python)
|
||||
[#]: author: (Archit Modi (Red Hat) https://opensource.com/users/architmodi/users/greg-p/users/oz123)
|
||||
|
||||
Bash vs. Python: Which language should you use?
|
||||
======
|
||||
Both programming languages have pros and cons that make them better for
|
||||
some tasks than others.
|
||||
![][1]
|
||||
|
||||
[Bash][2] and [Python][3] are most automation engineers' favorite programming languages. Both have pros and cons, and sometimes it can be hard to choose which one you should use. The honest answer is: It depends on the task, the scope, the context, and the complexity of the task.
|
||||
|
||||
Let's compare these two languages to get a better understanding of where each one shines.
|
||||
|
||||
### Bash
|
||||
|
||||
* Is a Linux/Unix shell command language
|
||||
* Is great for writing shell scripts that use command line interface (CLI) utilities, utilizing output from one command to another (piping), and executing simple tasks (up to 100 lines of code)
|
||||
* Can utilize command-line commands and utilities as-is
|
||||
* Has better startup time than Python but poor execution time performance
|
||||
* Does not come preinstalled in Windows; your script might not be compatible with multiple operating systems, but Bash is the default shell on most Linux/Unix systems
|
||||
* Is _not_ fully compatible with other shells (e.g., csh, zsh, fish)
|
||||
* Piping ("|") CLI utilities like sed, awk, grep, etc. can slow its performance
|
||||
* Lacks many functions, objects, data structures, and multi-threading, which limits its use for complex scripting/programming
|
||||
* Lacks good debugging tools and utilities
|
||||
|
||||
|
||||
|
||||
### Python
|
||||
|
||||
* Is an object-oriented programming (OOP) language, so it's more general purpose than Bash
|
||||
* Can be used for almost any task
|
||||
* Works on most major operating systems and is also installed by default on most Unix/Linux systems
|
||||
* Is very similar to writing pseudo code
|
||||
* Has simple, clear, easy-to-learn, and easy-to-read syntax
|
||||
* Has lots of libraries, documentation, and an active community
|
||||
* Provides better error handling features than Bash
|
||||
* Has better debugging tools and utilities than Bash, which makes it a great language for developing complex software applications involving many lines of code
|
||||
* Applications (or scripts) can contain many third-party dependencies that must be installed before executing them
|
||||
* Requires writing more lines of code for simple tasks than Bash does
|
||||
|
||||
|
||||
|
||||
I hope these lists give you a better understanding of which language to use and when to use it.
|
||||
|
||||
Which language do you use more in your day-to-day work, Bash or Python? Please share in the comments.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/19/4/bash-vs-python
|
||||
|
||||
作者：[Archit Modi (Red Hat)][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://opensource.com/users/architmodi/users/greg-p/users/oz123
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/computer_happy_sad_developer_programming.png?itok=72nkfSQ_
|
||||
[2]: /article/18/7/admin-guide-bash
|
||||
[3]: /article/17/11/5-approaches-learning-python
|
||||
@@ -0,0 +1,94 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (Linux Server Hardening Using Idempotency with Ansible: Part 1)
|
||||
[#]: via: (https://www.linux.com/blog/linux-server-hardening-using-idempotency-ansible-part-1)
|
||||
[#]: author: (Chris Binnie https://www.linux.com/users/chrisbinnie)
|
||||
|
||||
Linux Server Hardening Using Idempotency with Ansible: Part 1
|
||||
======
|
||||
|
||||
![][1]
|
||||
|
||||
[Creative Commons Zero][2]
|
||||
|
||||
I think it’s safe to say that the need to frequently update the packages on our machines has been firmly drilled into us. To ensure the use of latest features and also keep security bugs to a minimum, skilled engineers and even desktop users are well-versed in the need to update their software.
|
||||
|
||||
Hardware, software and SaaS (Software as a Service) vendors have also firmly embedded the word “firewall” into our vocabulary for both domestic and industrial uses to protect our computers. In my experience, however, even within potentially more sensitive commercial environments, few engineers actively tweak the operating system (OS) they’re working on, to any great extent at least, to bolster security.
|
||||
|
||||
Standard fare on Linux systems, for example, might mean looking at configuring a larger swap file to cope with your hungry application’s demands. Or, maybe adding a separate volume to your server for extra disk space, specifying a more performant CPU at launch time, installing a few of your favorite DevOps tools, or chucking a couple of certificates onto the filesystem for each new server you build. This isn’t quite the same thing.
|
||||
|
||||
### Improve your Security Posture
|
||||
|
||||
What I am specifically referring to is a mixture of compliance and security, I suppose. In short, there’s a surprisingly large number of areas in which a default OS can improve its security posture. We can agree that tweaking certain aspects of an OS are a little riskier than others. Consider your network stack, for example. Imagine that, completely out of the blue, your server’s networking suddenly does something unexpected and causes you troubleshooting headaches or even some downtime. This might happen because a new application or updated package suddenly expects routing to behave in a less-common way or needs a specific protocol enabled to function correctly.
|
||||
|
||||
However, there are many changes that you can make to your servers without suffering any sleepless nights. The version and flavor of an OS helps determine which changes and to what extent you might want to comfortably make. Most importantly though what’s good for the goose is rarely good for the gander. In other words every single server estate has different, both broad and subtle, requirements which makes each use case unique. And, don’t forget that a database server also has very different needs to a web server so you can have a number of differing needs even within one small cluster of servers.
|
||||
|
||||
Over the last few years I’ve introduced these hardening and compliance tweaks more than a handful of times across varying server estates in my DevSecOps roles. The OSs have included: Debian, Red Hat Enterprise Linux (RHEL) and their respective derivatives (including what I suspect will be the increasingly popular RHEL derivative, Amazon Linux). There have been times that, admittedly including a multitude of relatively tiny tweaks, the number of changes to a standard server build was into the hundreds. It all depended on the time permitted for the work, the appetite for any risks and the generic or specific nature of the OS tweaks.
|
||||
|
||||
In this article, we’ll discuss the theory around something called idempotency which, in hand with an automation tool such as Ansible, can provide the ongoing improvements to your server estate’s security posture. For good measure we’ll also look at a number of Ansible playbook examples and additionally refer to online resources so that you can introduce idempotency to a server estate near you.
|
||||
|
||||
### Say What?
|
||||
|
||||
In simple terms the word “idempotent” just means returning something back to how it was prior to a change. It can also mean that lots of things you wanted to be the same, for consistency, are exactly the same, too.
|
||||
|
||||
Picture that in action for a moment on a server estate; we’ll use AWS (Amazon Web Services) as our example. You create a new server image (Amazon Machine Images == AMIs) precisely how you want it with compliance and hardening introduced, custom packages, the removal of unwanted packages, SSH keys, user accounts etc and then spin up twenty servers using that AMI.
|
||||
|
||||
You know for certain that all the servers, at least at the time that they are launched, are absolutely identical. Trust me when I say that this is a “good thing” ™. The lack of what’s known as “config drift” means that if one package on a server needs updated for security reasons then all the servers need that package updated too. Or if there’s a typo in a config file that’s breaking an application then it affects all servers equally. There’s less administrative overhead, less security risk and greater levels of predictability in terms of achieving better uptime.
|
||||
|
||||
What about config drift from a security perspective? As you’ve guessed it’s definitely not welcome. That’s because engineers making manual changes to a “base OS build” can only lead to heartache and stress. The predictability of how a system is working suffers greatly as a result and servers running unique config become less reliable. These server systems are known as “snowflakes” as they’re unique but far less beautiful than actual snow.
|
||||
|
||||
Equally an attacker might have managed to breach one aspect, component or service on a server but not all of its facets. By rewriting our base config again and again we’re able to, with 100% certainty (if it’s set up correctly), predict exactly what a server will look like and therefore how it will perform. Using various tools you can also trigger alarms if changes are detected to request that a pair of human eyes have a look to see if it’s a serious issue and then adjust the base config if needed.
|
||||
|
||||
To make our machines idempotent we might overwrite our config changes every 20 or 30 minutes, for example. When it comes to running servers, that in essence, is what is meant by idempotency.
|
||||
|
||||
### Central Station
|
||||
|
||||
My mechanism of choice for repeatedly writing config across a large number of servers is running Ansible playbooks. It’s relatively easy to implement and removes the all-too-painful additional logic required when using shell scripts. Of the popular configuration management tools I’ve seen in action is Puppet, used successfully on a large government estate in an idempotent manner, but I prefer Ansible due to its more logical syntax (to my mind at least) and its readily available documentation.
|
||||
|
||||
Before we look at some simple Ansible examples of hardening an OS with idempotency in mind we should explore how to trigger our Ansible playbooks.
|
||||
|
||||
This is a larger area for debate than you might first imagine. Say, for example, you have nicely segmented server estate with production servers being carefully locked away from development servers, sitting behind a production-grade firewall. Consider the other servers on the estate, belonging to staging (pre-production) or other development environments, intentionally having different access permissions for security reasons.
|
||||
|
||||
If you’re going to run a centralized server that has superuser permissions (which are required to make privileged changes to your core system files) then that server will need to have high-level access permissions potentially across your entire server estate. It must therefore be guarded very closely.
|
||||
|
||||
You will also want to test your playbooks against development environments (in plural) to test their efficacy which means you’ll probably need two all-powerful centralised Ansible servers, one for production and one for the multiple development environments.
|
||||
|
||||
The actual approach of how to achieve other logistical issues is up for debate and I’ve heard it discussed a few times. Bear in mind that Ansible runs using plain, old SSH keys (a feature that something other configuration management tools have started to copy over time) but ideally you want a mechanism for keeping non-privileged keys on your centralised servers so you’re not logging in as the “root” user across the estate every twenty minutes or thirty minutes.
|
||||
|
||||
From a network perspective I like the idea of having firewalling in place to enforce one-way traffic only into the environment that you’re affecting. This protects your centralised host so that a compromised server can’t attack that main Ansible host easily and then as a result gain access to precious SSH keys in order to damage the whole estate.
|
||||
|
||||
Speaking of which, are servers actually needed for a task like this? What about using AWS Lambda (<https://aws.amazon.com/lambda>) to execute your playbooks? A serverless approach stills needs to be secured carefully but unquestionably helps to limit the attack surface and also potentially reduces administrative responsibilities.
|
||||
|
||||
I suspect how this all-powerful server is architected and deployed is always going to be contentious and there will never be a one-size-fits-all approach but instead a unique, bespoke solution will be required for every server estate.
|
||||
|
||||
### How Now, Brown Cow
|
||||
|
||||
It’s important to think about how often you run your Ansible and also how to prepare for your first execution of the playbook. Let’s get the frequency of execution out of the way first as it’s the easiest to change in the future.
|
||||
|
||||
My preference would be three times an hour or instead every thirty minutes. If we include enough detail in our configuration then our playbooks might prevent an attacker gaining a foothold on a system as the original configuration overwrites any altered config. Twenty minutes seems more appropriate to my mind.
|
||||
|
||||
Again, this is an aspect you need to have a think about. You might be dumping small config databases locally onto a filesystem every sixty minutes for example and that scheduled job might add an extra little bit of undesirable load to your server meaning you have to schedule around it.
|
||||
|
||||
Next time, we’ll take a look at some specific changes that can be made to various systems.
|
||||
|
||||
_Chris Binnie’s latest book, Linux Server Security: Hack and Defend, shows you how to make your servers invisible and perform a variety of attacks. You can find out more about DevSecOps, containers and Linux security on his website:[https://www.devsecops.cc][3]_
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.linux.com/blog/linux-server-hardening-using-idempotency-ansible-part-1
|
||||
|
||||
作者：[Chris Binnie][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://www.linux.com/users/chrisbinnie
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://www.linux.com/sites/lcom/files/styles/rendered_file/public/geometric-1732847_1280.jpg?itok=YRux0Tua
|
||||
[2]: /LICENSES/CATEGORY/CREATIVE-COMMONS-ZERO
|
||||
[3]: https://www.devsecops.cc/
|
||||
54
sources/tech/20190409 5 Linux rookie mistakes.md
Normal file
54
sources/tech/20190409 5 Linux rookie mistakes.md
Normal file
@@ -0,0 +1,54 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (5 Linux rookie mistakes)
|
||||
[#]: via: (https://opensource.com/article/19/4/linux-rookie-mistakes)
|
||||
[#]: author: (Jen Wike Huger (Red Hat) https://opensource.com/users/jen-wike/users/bcotton/users/petercheer/users/greg-p/users/greg-p)
|
||||
|
||||
5 Linux rookie mistakes
|
||||
======
|
||||
Linux enthusiasts share some of the biggest mistakes they made.
|
||||
![magnifying glass on computer screen, finding a bug in the code][1]
|
||||
|
||||
It's smart to learn new skills throughout your life—it keeps your mind nimble and makes you more competitive in the job market. But some skills are harder to learn than others, especially those where small rookie mistakes can cost you a lot of time and trouble when you're trying to fix them.
|
||||
|
||||
Take learning [Linux][2], for example. If you're used to working in a Windows or MacOS graphical interface, moving to Linux, with its unfamiliar commands typed into a terminal, can have a big learning curve. But the rewards are worth it, as the millions and millions of people who have gone before you have proven.
|
||||
|
||||
That said, the journey won't be without pitfalls. We asked some of Linux enthusiasts to think back to when they first started using Linux and tell us about the biggest mistakes they made.
|
||||
|
||||
"Don't go into [any sort of command line interface (CLI) work] with an expectation that commands work in rational or consistent ways, as that is likely to lead to frustration. This is not due to poor design choices—though it can feel like it when you're banging your head against the proverbial desk—but instead reflects the fact that these systems have evolved and been added onto through generations of software and OS evolution. Go with the flow, write down or memorize the commands you need, and (try not to) get frustrated when [things aren't what you'd expect][3]." _—[Gina Likins][4]_
|
||||
|
||||
"As easy as it might be to just copy and paste commands to make the thing go, read the command first and at least have a general understanding of the actions that are about to be performed. Especially if there is a pipe command. Double especially if there is more than one. There are a lot of destructive commands that look innocuous until you realize what they can do (e.g., **rm** , **dd** ), and you don't want to accidentally destroy things. (Ask me how I know.)" _—[Katie McLaughlin][5]_
|
||||
|
||||
"Early on in my Linux journey, I wasn't as aware of the importance of knowing where you are in the filesystem. I was deleting some file in what I thought was my home directory, and I entered **sudo rm -rf *** and deleted all of the boot files on my system. Now, I frequently use **pwd** to ensure that I am where I think I am before issuing such commands. Fortunately for me, I was able to boot my wounded laptop with a USB drive and recover my files." _—[Don Watkins][6]_
|
||||
|
||||
"Do not reset permissions on the entire file system to [777][7] because you think 'permissions are hard to understand' and you want an application to have access to something." _—[Matthew Helmke][8]_
|
||||
|
||||
"I was removing a package from my system, and I did not check what other packages it was dependent upon. I just let it remove whatever it wanted and ended up causing some of my important programs to crash and become unavailable." _—[Kedar Vijay Kulkarni][9]_
|
||||
|
||||
What mistakes have you made while learning to use Linux? Share them in the comments.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/19/4/linux-rookie-mistakes
|
||||
|
||||
作者：[Jen Wike Huger (Red Hat)][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://opensource.com/users/jen-wike/users/bcotton/users/petercheer/users/greg-p/users/greg-p
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/mistake_bug_fix_find_error.png?itok=PZaz3dga (magnifying glass on computer screen, finding a bug in the code)
|
||||
[2]: https://opensource.com/resources/linux
|
||||
[3]: https://lintqueen.com/2017/07/02/learning-while-frustrated/
|
||||
[4]: https://opensource.com/users/lintqueen
|
||||
[5]: https://opensource.com/users/glasnt
|
||||
[6]: https://opensource.com/users/don-watkins
|
||||
[7]: https://www.maketecheasier.com/file-permissions-what-does-chmod-777-means/
|
||||
[8]: https://twitter.com/matthewhelmke
|
||||
[9]: https://opensource.com/users/kkulkarn
|
||||
131
sources/tech/20190409 5 open source mobile apps.md
Normal file
131
sources/tech/20190409 5 open source mobile apps.md
Normal file
@@ -0,0 +1,131 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (5 open source mobile apps)
|
||||
[#]: via: (https://opensource.com/article/19/4/mobile-apps)
|
||||
[#]: author: (Chris Hermansen (Community Moderator) https://opensource.com/users/clhermansen/users/bcotton/users/clhermansen/users/bcotton/users/clhermansen)
|
||||
|
||||
5 open source mobile apps
|
||||
======
|
||||
You can count on these apps to meet your needs for productivity,
|
||||
communication, and entertainment.
|
||||
![][1]
|
||||
|
||||
Like most people in the world, I'm rarely further than an arm's reach from my smartphone. My Android device provides a seemingly limitless number of communication, productivity, and entertainment services thanks to the open source mobile apps I've installed from Google Play and F-Droid.
|
||||
|
||||
Of the many open source apps on my phone, the following five are the ones I consistently turn to whether I want to listen to music; connect with friends, family, and colleagues; or get work done on the go.
|
||||
|
||||
### MPDroid
|
||||
|
||||
_An Android controller for the Music Player Daemon (MPD)_
|
||||
|
||||
![MPDroid][2]
|
||||
|
||||
MPD is a great way to get music from little music server computers out to the big black stereo boxes. It talks straight to ALSA and therefore to the Digital-to-Analog Converter ([DAC][3]) via the ALSA hardware interface, and it can be controlled over my network—but by what? Well, it turns out that MPDroid is a great MPD controller. It manages my music database, displays album art, handles playlists, and supports internet radio. And it's open source, so if something doesn't work…
|
||||
|
||||
MPDroid is available on [Google Play][4] and [F-Droid][5].
|
||||
|
||||
### RadioDroid
|
||||
|
||||
_An Android internet radio tuner that I use standalone and with Chromecast_
|
||||
|
||||
**
|
||||
|
||||
**
|
||||
|
||||
**
|
||||
|
||||
_![RadioDroid][6]_
|
||||
|
||||
RadioDroid is to internet radio as MPDroid is to managing my music database; essentially, RadioDroid is a frontend to [Internet-Radio.com][7]. Moreover, RadioDroid can be enjoyed by plugging headphones into the Android device, by connecting the Android device directly to the stereo via the headphone jack or USB, or by using its Chromecast capability with a compatible device. It's a fine way to check the weather in Finland, listen to the Spanish top 40, or hear the latest news from down under.
|
||||
|
||||
RadioDroid is available on [Google Play][8] and [F-Droid][9].
|
||||
|
||||
### Signal
|
||||
|
||||
_A secure messaging client for Android, iOS, and desktop_
|
||||
|
||||
**
|
||||
|
||||
**
|
||||
|
||||
**
|
||||
|
||||
_![Signal][10]_
|
||||
|
||||
If you like WhatsApp but are bothered by its [getting-closer-every-day][11] relationship to Facebook, Signal should be your next thing. The only problem with Signal is convincing your contacts they're better off replacing WhatsApp with Signal. But other than that, it has a similar interface; great voice and video calling; great encryption; decent anonymity; and it's supported by a foundation that doesn't plan to monetize your use of the software. What's not to like?
|
||||
|
||||
Signal is available for [Android][12], [iOS][13], and [desktop][14].
|
||||
|
||||
### ConnectBot
|
||||
|
||||
_Android SSH client_
|
||||
|
||||
**
|
||||
|
||||
**
|
||||
|
||||
**
|
||||
|
||||
_![ConnectBot][15]_
|
||||
|
||||
Sometimes I'm far away from my computer, but I need to log into the server to do something. [ConnectBot][16] is a great solution for moving SSH sessions onto my phone.
|
||||
|
||||
ConnectBot is available on [Google Play][17].
|
||||
|
||||
### Termux
|
||||
|
||||
_Android terminal emulator with many familiar utilities_
|
||||
|
||||
**
|
||||
|
||||
**
|
||||
|
||||
**
|
||||
|
||||
_![Termux][18]_
|
||||
|
||||
Have you ever needed to run an **awk** script on your phone? [Termux][19] is your solution. If you need to do terminal-type stuff, and you don't want to maintain an SSH connection to a remote computer the whole time, bring the files over to your phone with ConnectBot, quit the session, do your stuff in Termux, and send the results back with ConnectBot.
|
||||
|
||||
Termux is available on [Google Play][20] and [F-Droid][21].
|
||||
|
||||
* * *
|
||||
|
||||
What are your favorite open source mobile apps for work or fun? Please share them in the comments.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/19/4/mobile-apps
|
||||
|
||||
作者：[Chris Hermansen (Community Moderator)][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://opensource.com/users/clhermansen/users/bcotton/users/clhermansen/users/bcotton/users/clhermansen
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/rh_003588_01_rd3os.combacktoschoolserieshe_rh_041x_0.png?itok=tfg6_I78
|
||||
[2]: https://opensource.com/sites/default/files/uploads/mpdroid.jpg (MPDroid)
|
||||
[3]: https://opensource.com/article/17/4/fun-new-gadget
|
||||
[4]: https://play.google.com/store/apps/details?id=com.namelessdev.mpdroid&hl=en_US
|
||||
[5]: https://f-droid.org/en/packages/com.namelessdev.mpdroid/
|
||||
[6]: https://opensource.com/sites/default/files/uploads/radiodroid.png (RadioDroid)
|
||||
[7]: https://www.internet-radio.com/
|
||||
[8]: https://play.google.com/store/apps/details?id=net.programmierecke.radiodroid2
|
||||
[9]: https://f-droid.org/en/packages/net.programmierecke.radiodroid2/
|
||||
[10]: https://opensource.com/sites/default/files/uploads/signal.png (Signal)
|
||||
[11]: https://opensource.com/article/19/3/open-messenger-client
|
||||
[12]: https://play.google.com/store/apps/details?id=org.thoughtcrime.securesms
|
||||
[13]: https://itunes.apple.com/us/app/signal-private-messenger/id874139669?mt=8
|
||||
[14]: https://signal.org/download/
|
||||
[15]: https://opensource.com/sites/default/files/uploads/connectbot.png (ConnectBot)
|
||||
[16]: https://connectbot.org/
|
||||
[17]: https://play.google.com/store/apps/details?id=org.connectbot
|
||||
[18]: https://opensource.com/sites/default/files/uploads/termux.jpg (Termux)
|
||||
[19]: https://termux.com/
|
||||
[20]: https://play.google.com/store/apps/details?id=com.termux
|
||||
[21]: https://f-droid.org/packages/com.termux/
|
||||
66
sources/tech/20190409 AI Ops- Let the data talk.md
Normal file
66
sources/tech/20190409 AI Ops- Let the data talk.md
Normal file
@@ -0,0 +1,66 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (AI Ops: Let the data talk)
|
||||
[#]: via: (https://www.networkworld.com/article/3388217/ai-ops-let-the-data-talk.html#tk.rss_all)
|
||||
[#]: author: (Marie Fiala, Director of Portfolio Marketing for Blue Planet at Ciena )
|
||||
|
||||
AI Ops: Let the data talk
|
||||
======
|
||||
The catalysts and ROI of AI-powered network analytics for automated operations were the focus of discussion for service providers at the recent FutureNet conference in London. Blue Planet’s Marie Fiala details the conversation.
|
||||
![metamorworks][1]
|
||||
|
||||
![Marie Fiala, Director of Portfolio Marketing for Blue Planet at Ciena][2]
|
||||
|
||||
_The catalysts and ROI of AI-powered network analytics for automated operations were the focus of discussion for service providers at the recent FutureNet conference in London. Blue Planet’s Marie Fiala details the conversation._
|
||||
|
||||
Do we need perfect data? Or is ‘good enough’ data good enough? Certainly, there is a need to find a pragmatic approach or else one could get stalled in analysis-paralysis. Is closed-loop automation the end goal? Or is human-guided open loop automation desired? If the quality of data defines the quality of the process, then for closed-loop automation of critical business processes, one needs near-perfect data. Is that achievable?
|
||||
|
||||
These issues were discussed and debated at the recent FutureNet conference in London, where the show focused on solving network operators’ toughest challenges. Industry presenters and panelists stayed true to the themes of AI and automation, all touting the necessity of these interlinked software technologies, yet there were varied opinions on approaches. Network and service providers such as BT, Colt, Deutsche Telekom, KPN, Orange, Telecom Italia, Telefonica, Telenor, Telia, Telus, Turk Telkom, and Vodafone weighed in on the discussion.
|
||||
|
||||
**Catalysts for AI-powered analytics**
|
||||
|
||||
On one point, most service providers were in agreement: there is a need to identify a specific business use case with measurable ROI, as an initial validation point when introducing AI-powered analytics into operations.
|
||||
|
||||
Host operator, Vodafone, positioned 5G as the catalyst. With the advent of 5G technology supporting 100x connections, 10Gbps super-bandwidth, and ultra-low <10ms latency, the volume, velocity and variety of data is exploding. It’s a virtuous cycle – 5G technologies generate a plethora of data, and conversely, a 5G network requires data-driven automation to function accurately and optimally (how else can virtualized network functions be managed in real-time?).
|
||||
|
||||
![5G as catalyst for digitalisation][3]
|
||||
|
||||
Another operator stated that the ‘AI gateway for telecom’ is the customer experience domain, citing how agents can use analytics to better serve the customer base. For another operator, capacity planning is the killer use case: first leverage AI to understand what’s going on in your network, then use predictive AI for planning so that you can make smarter investment decisions. Another point of view was that service assurance is the area where the most benefits from AI will be realized. There was even mention of ‘AI as a business’ by enabling the creation of new services, such as home assistants. At the broadest level, it was noted that AI allows network operators to remain relevant in the eyes of customers.
|
||||
|
||||
**The human side of AI and automation**
|
||||
|
||||
When it comes to implementation, the significant human impact of AI and automation was not overlooked. Across the board, service providers acknowledged that a new skillset is needed in network operations centers. Network engineers have to upskill to become data scientists and DevOps developers in order to best leverage the new AI-driven software tools.
|
||||
|
||||
Furthermore, it is a challenge to recruit specialist AI experts, especially since web-scale providers are also vying for the same talent. On the flip side of the dire need for new skills, there is also a shortage of qualified experts in legacy technologies. Operators need automated, zero-touch management before the workforce retires!
|
||||
|
||||
![FutureNet panelists discuss how automated AI can be leveraged as a competitive differentiator][4]
|
||||
|
||||
**The ROI of AI**
|
||||
|
||||
In many cases, the approach to AI has been a technology-driven ‘Field of Dreams’: build it and they will come. A strategic decision was made to hire experts, build data lakes, collect data, and then the business case that yielded positive returns was discovered. In other cases, the business use case came first. But no matter what the approach, the ROI was significant.
|
||||
|
||||
These positive results are spurring determination for continued research to uncover ever more areas where AI can deliver tangible benefits. This is however no easy task – one operator highlighted that data collection takes 80% of the effort, with the remaining 20% spent on development of algorithms. For AI to really proliferate throughout all aspects of operations, that trend needs to be reversed. It needs to be relatively easy and quick to collect massive amounts of heterogeneous data, aggregate it, and correlate it. This would allow investment to be overwhelmingly applied to the development of predictive and prescriptive analytics tailored to specific use cases, and to enacting intelligent closed-loop automation. Only then will data be able to truly talk – and tell us what we haven’t even thought of yet.
|
||||
|
||||
[Discover Intelligent Automation at Blue Planet][5]
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.networkworld.com/article/3388217/ai-ops-let-the-data-talk.html#tk.rss_all
|
||||
|
||||
作者：[Marie Fiala, Director of Portfolio Marketing for Blue Planet at Ciena][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://images.idgesg.net/images/article/2019/04/istock-957627892-100793278-large.jpg
|
||||
[2]: https://images.idgesg.net/images/article/2019/04/marla-100793273-small.jpg
|
||||
[3]: https://images.idgesg.net/images/article/2019/04/ciena-post-5-image-1-100793275-large.jpg
|
||||
[4]: https://images.idgesg.net/images/article/2019/04/ciena-post-5-image-2-100793276-large.jpg
|
||||
[5]: https://www.blueplanet.com/resources/Intelligent-Automation-Driving-Digital-Automation-for-Service-Providers.html?utm_campaign=X1058319&utm_source=NWW&utm_term=BPVision&utm_medium=newsletter
|
||||
@@ -1,355 +0,0 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( NeverKnowsTomorrow )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (Four Methods To Add A User To Group In Linux)
|
||||
[#]: via: (https://www.2daygeek.com/linux-add-user-to-group-primary-secondary-group-usermod-gpasswd/)
|
||||
[#]: author: (Magesh Maruthamuthu https://www.2daygeek.com/author/magesh/)
|
||||
|
||||
Four Methods To Add A User To Group In Linux
|
||||
======
|
||||
|
||||
Linux groups are organization units which are used to manage user accounts in Linux.
|
||||
|
||||
It has unique numerical identification number for each users and groups in the Linux system.
|
||||
|
||||
It’s called a userid (UID) and a groupid (GID). The main purpose of groups is to define a set of privileges to the member of the group.
|
||||
|
||||
They all can perform the particular operations but not others.
|
||||
|
||||
There are two types of default groups are available in Linux. Each user should have exactly one primary group and any number of secondary groups.
|
||||
|
||||
* **Primary Group:** Primary group has been added to the user when the user account creation. It’s typically the name of the user. The primary group is applied to the user when performing any actions such as creating new files (or directories), modifying files, or executing commands, etc,. The user primary group information is stored in the `/etc/passwd` file.
|
||||
* **Secondary Group:** It’s known as Supplementary Groups. It allows the group of users to perform the particular action in the same group members files.
|
||||
Say for example, if you would like to allow few users to run Apache (httpd) service command then it will perfectly suits.
|
||||
|
||||
|
||||
|
||||
You may have interested in the following articles which is related to user management.
|
||||
|
||||
* [Three Methods To Create An User Account In Linux?][1]
|
||||
* [How To Create The Bulk Users In Linux?][2]
|
||||
* [How to Update/Change Users Password in Linux Using Different Ways][3]
|
||||
|
||||
|
||||
|
||||
It can be done using the following four methods.
|
||||
|
||||
* **`usermod:`** The usermod command modifies the system account files to reflect the changes that are specified on the command line.
|
||||
* **`gpasswd:`** The gpasswd command is used to administer /etc/group, and /etc/gshadow. Every group can have administrators, members and a password.
|
||||
* **`Shell Script:`** Shell scripts are allow administrator to automate the required tasks.
|
||||
* **`Manual Method:`** We can manually add the users into any group by editing the `/etc/group` file.
|
||||
|
||||
|
||||
|
||||
I assume that you already have the necessary group and users for this activity. In this example, we are going to use following users and groups `user1`, `user2`, `user3` and group is `mygroup` and `mygroup1`.
|
||||
|
||||
Before making the changes, i would like to check the users and group information. See the details below.
|
||||
|
||||
I could see the below users were associate with their own group and not with others.
|
||||
|
||||
```
|
||||
# id user1
|
||||
uid=1008(user1) gid=1008(user1) groups=1008(user1)
|
||||
|
||||
# id user2
|
||||
uid=1009(user2) gid=1009(user2) groups=1009(user2)
|
||||
|
||||
# id user3
|
||||
uid=1010(user3) gid=1010(user3) groups=1010(user3)
|
||||
```
|
||||
|
||||
I could see there is no users are associated in this group.
|
||||
|
||||
```
|
||||
# getent group mygroup
|
||||
mygroup:x:1012:
|
||||
|
||||
# getent group mygroup1
|
||||
mygroup1:x:1013:
|
||||
```
|
||||
|
||||
### Method-1: What Is usermod Command?
|
||||
|
||||
The usermod command modifies the system account files to reflect the changes that are specified on the command line.
|
||||
|
||||
### How to Add an Existing User to Secondary or Supplementary Group Using usermod Command?
|
||||
|
||||
To add an existing user to a secondary group, use the usermod command with `-G` option and the name of the group.
|
||||
Syntax
|
||||
|
||||
```
|
||||
# usermod [-G] [GroupName] [UserName]
|
||||
```
|
||||
|
||||
You will be getting an error message if the given user or group doesn’t exist in your system. If you doesn’t get any error then the user has been added to the corresponding group.
|
||||
|
||||
```
|
||||
# usermod -a -G mygroup user1
|
||||
```
|
||||
|
||||
Let me see the output using id command. Yes, it’s added successfully.
|
||||
|
||||
```
|
||||
# id user1
|
||||
uid=1008(user1) gid=1008(user1) groups=1008(user1),1012(mygroup)
|
||||
```
|
||||
|
||||
### How to Add an Existing User to Multiple Secondary or Supplementary Groups Using usermod Command?
|
||||
|
||||
To add an existing user to multiple secondary groups, use the usermod command with `-G` option and the name of the groups with comma.
|
||||
|
||||
Syntax
|
||||
|
||||
```
|
||||
# usermod [-G] [GroupName1,GroupName2] [UserName]
|
||||
```
|
||||
|
||||
In this example, we are going to add the `user2` into `mygroup` and `mygroup1`.
|
||||
|
||||
```
|
||||
# usermod -a -G mygroup,mygroup1 user2
|
||||
```
|
||||
|
||||
Let me see the output using id command. Yes, `user2` is successfully added into `mygroup` and `mygroup1`.
|
||||
|
||||
```
|
||||
# id user2
|
||||
uid=1009(user2) gid=1009(user2) groups=1009(user2),1012(mygroup),1013(mygroup1)
|
||||
```
|
||||
|
||||
### How to Change a User’s Primary Group?
|
||||
|
||||
To change a user’s primary group, use the usermod command with `-g` option and the name of the group.
|
||||
|
||||
Syntax
|
||||
|
||||
```
|
||||
# usermod [-g] [GroupName] [UserName]
|
||||
```
|
||||
|
||||
We have to use `-g` to change user’s primary group.
|
||||
|
||||
```
|
||||
# usermod -g mygroup user3
|
||||
```
|
||||
|
||||
Let see the output. Yes, it has been successfully changed. Now, it’s showing `mygroup` as `user3` primary group instead of `user3`.
|
||||
|
||||
```
|
||||
# id user3
|
||||
uid=1010(user3) gid=1012(mygroup) groups=1012(mygroup)
|
||||
```
|
||||
|
||||
### Method-2: What Is gpasswd Command?
|
||||
|
||||
The gpasswd command is used to administer /etc/group, and /etc/gshadow. Every group can have administrators, members and a password.
|
||||
|
||||
### How to Add an Existing User to Secondary or Supplementary Group Using gpasswd Command?
|
||||
|
||||
To add an existing user to a secondary group, use the gpasswd command with `-M` option and the name of the group.
|
||||
|
||||
Syntax
|
||||
|
||||
```
|
||||
# gpasswd [-M] [UserName] [GroupName]
|
||||
```
|
||||
|
||||
In this example, we are going to add the `user1` into `mygroup`.
|
||||
|
||||
```
|
||||
# gpasswd -M user1 mygroup
|
||||
```
|
||||
|
||||
Let me see the output using id command. Yes, `user1` is successfully added into `mygroup`.
|
||||
|
||||
```
|
||||
# id user1
|
||||
uid=1008(user1) gid=1008(user1) groups=1008(user1),1012(mygroup)
|
||||
```
|
||||
|
||||
### How to Add The Multiple User’s to Secondary or Supplementary Group Using gpasswd Command?
|
||||
|
||||
To add the multiple users to a secondary group, use the gpasswd command with `-M` option and the name of the group.
|
||||
|
||||
Syntax
|
||||
|
||||
```
|
||||
# gpasswd [-M] [UserName1,UserName2] [GroupName]
|
||||
```
|
||||
|
||||
In this example, we are going to add the `user2` and `user3` into `mygroup1`.
|
||||
|
||||
```
|
||||
# gpasswd -M user2,user3 mygroup1
|
||||
```
|
||||
|
||||
Let me see the output using getent command. Yes, `user2` and `user3` are successfully added into `mygroup1`.
|
||||
|
||||
```
|
||||
# getent group mygroup1
|
||||
mygroup1:x:1013:user2,user3
|
||||
```
|
||||
|
||||
### How to Remove a User From a Group Using gpasswd Command?
|
||||
|
||||
To remove the user from the group, use the gpasswd command with `-d` option and the name of the user and group.
|
||||
|
||||
Syntax
|
||||
|
||||
```
|
||||
# gpasswd [-d] [UserName] [GroupName]
|
||||
```
|
||||
|
||||
In this example, we are going to remove the `user1` from `mygroup`.
|
||||
|
||||
```
|
||||
# gpasswd -d user1 mygroup
|
||||
Removing user user1 from group mygroup
|
||||
```
|
||||
|
||||
### Method-3: Using Shell Script?
|
||||
|
||||
Based on the above examples what i came to know is the `usermod` command doesn’t has capable to add multiple users into the group but it can be done through the `gpasswd` command.
|
||||
|
||||
However, it will overwrite the existing users which are currently associated on the group.
|
||||
|
||||
For example, `user1` has already associated with `mygroup`. If you would like to add `user2` and `user3` into the `mygroup` with `gpasswd` command, it doesn’t work as expected and it over right the group instead of modifying it.
|
||||
|
||||
What would be the solution if you would like to add multiple users to multiple groups?
|
||||
|
||||
There is no default option is available in both of the commands to achieve this.
|
||||
|
||||
Hence, we need to write a small shell script to achieve this.
|
||||
|
||||
### Method-3a: How to Add The Multiple Users to Secondary or Supplementary Group Using gpasswd Command?
|
||||
|
||||
Create the following small shell script if you would like to add the multiple users to secondary or supplementary group using gpasswd command.
|
||||
|
||||
Create The Users list. Each user should be in separate line.
|
||||
|
||||
```
|
||||
$ cat user-lists.txt
|
||||
user1
|
||||
user2
|
||||
user3
|
||||
```
|
||||
|
||||
Use the following shell script to add multiple users to single secondary group.
|
||||
|
||||
```
|
||||
vi group-update.sh
|
||||
|
||||
#!/bin/bash
|
||||
for user in `cat user-lists.txt`
|
||||
do
|
||||
usermod -a -G mygroup $user
|
||||
done
|
||||
```
|
||||
|
||||
Set an executable permission to `group-update.sh` file.
|
||||
|
||||
```
|
||||
# chmod + group-update.sh
|
||||
```
|
||||
|
||||
Finally run the script to achieve this.
|
||||
|
||||
```
|
||||
# sh group-update.sh
|
||||
```
|
||||
|
||||
Let me see the output using getent command. Yes, `user1`, `user2` and `user3` are successfully added into `mygroup`.
|
||||
|
||||
```
|
||||
# getent group mygroup
|
||||
mygroup:x:1012:user1,user2,user3
|
||||
```
|
||||
|
||||
### Method-3a: How to Add The Multiple Users Into Multiple Secondary or Supplementary Group Using gpasswd Command?
|
||||
|
||||
Create the following small shell script if you would like to add the multiple users into multiple secondary or supplementary group using gpasswd command.
|
||||
|
||||
Create The Users list. Each user should be in separate line.
|
||||
|
||||
```
|
||||
$ cat user-lists.txt
|
||||
user1
|
||||
user2
|
||||
user3
|
||||
```
|
||||
|
||||
Create The Groups list. Each group should be in separate line.
|
||||
|
||||
```
|
||||
$ cat group-lists.txt
|
||||
mygroup
|
||||
mygroup1
|
||||
```
|
||||
|
||||
Use the following shell script to add multiple users to multiple secondary groups.
|
||||
|
||||
```
|
||||
#!/bin/sh
|
||||
for user in `more user-lists.txt`
|
||||
do
|
||||
for group in `more group-lists.txt`
|
||||
do
|
||||
usermod -a -G $group $user
|
||||
done
|
||||
done
|
||||
```
|
||||
|
||||
Set an executable permission to `group-update-1.sh` file.
|
||||
|
||||
```
|
||||
# chmod +x group-update-1.sh
|
||||
```
|
||||
|
||||
Finally run the script to achieve this.
|
||||
|
||||
```
|
||||
# sh group-update-1.sh
|
||||
```
|
||||
|
||||
Let me see the output using getent command. Yes, `user1`, `user2` and `user3` are successfully added into `mygroup`.
|
||||
|
||||
```
|
||||
# getent group mygroup
|
||||
mygroup:x:1012:user1,user2,user3
|
||||
```
|
||||
|
||||
Also, `user1`, `user2` and `user3` are successfully added into `mygroup1`.
|
||||
|
||||
```
|
||||
# getent group mygroup1
|
||||
mygroup1:x:1013:user1,user2,user3
|
||||
```
|
||||
|
||||
### Method-4: Manual Method To Add A User Into A Group In Linux?
|
||||
|
||||
We can manually add the users into any group by editing the `/etc/group` file.
|
||||
|
||||
Open the `/etc/group` file and search the group name where you want to update the users. Finally update the Users into the corresponding group.
|
||||
|
||||
```
|
||||
# vi /etc/group
|
||||
```
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.2daygeek.com/linux-add-user-to-group-primary-secondary-group-usermod-gpasswd/
|
||||
|
||||
作者：[Magesh Maruthamuthu][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://www.2daygeek.com/author/magesh/
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://www.2daygeek.com/linux-user-account-creation-useradd-adduser-newusers/
|
||||
[2]: https://www.2daygeek.com/how-to-create-the-bulk-users-in-linux/
|
||||
[3]: https://www.2daygeek.com/linux-passwd-chpasswd-command-set-update-change-users-password-in-linux-using-shell-script/
|
||||
@@ -0,0 +1,80 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (Juniper opens SD-WAN service for the cloud)
|
||||
[#]: via: (https://www.networkworld.com/article/3388030/juniper-opens-sd-wan-service-for-the-cloud.html#tk.rss_all)
|
||||
[#]: author: (Michael Cooney https://www.networkworld.com/author/Michael-Cooney/)
|
||||
|
||||
Juniper opens SD-WAN service for the cloud
|
||||
======
|
||||
Juniper rolls out its Contrail SD-WAN cloud offering.
|
||||
![Thinkstock][1]
|
||||
|
||||
Juniper has taken the wraps off a cloud-based SD-WAN service it says will ease the management and bolster the security of wired and wireless-connected branch office networks.
|
||||
|
||||
The Contrail SD-WAN cloud offering expands on the company’s existing on-premise ([SRX][2]-based) and virtual ([NFX][3]-based) SD-WAN offerings to include greater expansion possibilities – up to 10,000 spoke-attached sites and support for more variants of passive redundant hybrid WAN links – and topologies such as hub and spoke, partial, and dynamic full mesh, Juniper stated.
|
||||
|
||||
**More about SD-WAN**
|
||||
|
||||
* [How to buy SD-WAN technology: Key questions to consider when selecting a supplier][4]
|
||||
* [How to pick an off-site data-backup method][5]
|
||||
* [SD-Branch: What it is and why you’ll need it][6]
|
||||
* [What are the options for security SD-WAN?][7]
|
||||
|
||||
|
||||
|
||||
The service brings with it Juniper’s Contrail Service Orchestration package, which secures, automates, and runs the service life cycle across [NFX Series][3] Network Services Platforms, [EX Series][8] Ethernet Switches, [SRX Series][2] next-generation firewalls, and [MX Series][9] 5G Universal Routing Platforms. Ultimately it lets customers manage and set up SD-WANs all from a single portal.
|
||||
|
||||
The package is also a service orchestrator for the [vSRX][10] Virtual Firewall and [vMX][11] Virtual Router, available in public cloud marketplaces such as Amazon Web Services (AWS) and Microsoft Azure, Juniper said. The SD-WAN offering also includes integration with cloud security provider ZScaler.
|
||||
|
||||
Contrail Service Orchestration offers organizations visibility across SD-WAN, as well as branch wired and now wireless infrastructure. Monitoring and intelligent analytics offer real-time insight into network operations, allowing administrators to preempt looming threats and degradations, as well as pinpoint issues for faster recovery.
|
||||
|
||||
The new service also includes support for Juniper’s [recently acquired][12] Mist Systems wireless technology, which lets the service access and manage Mist’s wireless access points, allowing customers to meld wireless and wired networks.
|
||||
|
||||
Juniper recently closed the agreement to buy innovative wireless-gear-maker Mist for $405 million. Mist touts itself as having developed an artificial-intelligence-based wireless platform that makes Wi-Fi more predictable, reliable, and measurable.
|
||||
|
||||
With Contrail, administrators can control a growing mix of legacy and modern scale-out architectures while automating their operational workflows using software that provides smarter, easier-to-use automation, orchestration and infrastructure visibility, wrote Juniper CTO [Bikash Koley][13] in a [blog about the SD-WAN announcement][14].
|
||||
|
||||
“Management complexity and policy enforcement are traditional network administrator fears, while both data and network security are growing in importance for organizations of all sizes,” Koley stated. ** **“Cloud-delivered SD-WAN removes the complexity of software operations, arguably the most difficult part of Software Defined Networking.”
|
||||
|
||||
Analysts said the Juniper announcement could help the company compete in a super-competitive, rapidly evolving SD-WAN world.
|
||||
|
||||
“The announcement is more a ‘me too’ than a particular technological breakthrough,” said Lee Doyle, principal analyst with Doyle Research. “The Mist integration is what’s interesting here, and that could help them, but there are 15 to 20 other vendors that have the same technology, bigger partners, and bigger sales channels than Juniper does.”
|
||||
|
||||
Indeed the SD-WAN arena is a crowded one with Cisco, VMware, Silver Peak, Riverbed, Aryaka, Nokia, and Versa among the players.
|
||||
|
||||
The cloud-based Contrail SD-WAN offering is available as an annual or multi-year subscription.
|
||||
|
||||
Join the Network World communities on [Facebook][15] and [LinkedIn][16] to comment on topics that are top of mind.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.networkworld.com/article/3388030/juniper-opens-sd-wan-service-for-the-cloud.html#tk.rss_all
|
||||
|
||||
作者：[Michael Cooney][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://www.networkworld.com/author/Michael-Cooney/
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://images.idgesg.net/images/article/2018/01/cloud_network_blockchain_bitcoin_storage-100745950-large.jpg
|
||||
[2]: https://www.juniper.net/us/en/products-services/security/srx-series/
|
||||
[3]: https://www.juniper.net/us/en/products-services/sdn/nfx-series/
|
||||
[4]: https://www.networkworld.com/article/3323407/sd-wan/how-to-buy-sd-wan-technology-key-questions-to-consider-when-selecting-a-supplier.html
|
||||
[5]: https://www.networkworld.com/article/3328488/backup-systems-and-services/how-to-pick-an-off-site-data-backup-method.html
|
||||
[6]: https://www.networkworld.com/article/3250664/lan-wan/sd-branch-what-it-is-and-why-youll-need-it.html
|
||||
[7]: https://www.networkworld.com/article/3285728/sd-wan/what-are-the-options-for-securing-sd-wan.html?nsdr=true
|
||||
[8]: https://www.juniper.net/us/en/products-services/switching/ex-series/
|
||||
[9]: https://www.juniper.net/us/en/products-services/routing/mx-series/
|
||||
[10]: https://www.juniper.net/us/en/products-services/security/srx-series/vsrx/
|
||||
[11]: https://www.juniper.net/us/en/products-services/routing/mx-series/vmx/
|
||||
[12]: https://www.networkworld.com/article/3353042/juniper-grabs-mist-for-wireless-ai-cloud-service-delivery-technology.html
|
||||
[13]: https://www.networkworld.com/article/3324374/juniper-cto-talks-cloud-intent-computing-revolution-high-speed-networking-and-open-source-growth.html?nsdr=true
|
||||
[14]: https://forums.juniper.net/t5/Engineering-Simplicity/Cloud-Delivered-Branch-Simplicity-Now-Surpasses-SD-WAN/ba-p/461188
|
||||
[15]: https://www.facebook.com/NetworkWorld/
|
||||
[16]: https://www.linkedin.com/company/network-world
|
||||
@@ -0,0 +1,69 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (The Microsoft/BMW IoT Open Manufacturing Platform might not be so open)
|
||||
[#]: via: (https://www.networkworld.com/article/3387642/the-microsoftbmw-iot-open-manufacturing-platform-might-not-be-so-open.html#tk.rss_all)
|
||||
[#]: author: (Fredric Paul https://www.networkworld.com/author/Fredric-Paul/)
|
||||
|
||||
The Microsoft/BMW IoT Open Manufacturing Platform might not be so open
|
||||
======
|
||||
The new industrial IoT Open Manufacturing Platform from Microsoft and BMW runs only on Microsoft Azure. That could be an issue.
|
||||
![Martyn Williams][1]
|
||||
|
||||
Last week at [Hannover Messe][2], Microsoft and German carmaker BMW announced a partnership to build a hardware and software technology framework and reference architecture for the industrial internet of things (IoT), and foster a community to spread these smart-factory solutions across the automotive and manufacturing industries.
|
||||
|
||||
The stated goal of the [Open Manufacturing Platform (OMP)][3]? According to the press release, it's “to drive open industrial IoT development and help grow a community to build future [Industry 4.0][4] solutions.” To make that a reality, the companies said that by the end of 2019, they plan to attract four to six partners — including manufacturers and suppliers from both inside and outside the automotive industry — and to have rolled out at least 15 use cases operating in actual production environments.
|
||||
|
||||
**[ Read also:[An inside look at an IIoT-powered smart factory][5] | Get regularly scheduled insights: [Sign up for Network World newsletters][6] ]**
|
||||
|
||||
### Complex and proprietary is bad for IoT
|
||||
|
||||
It sounds like a great idea, right? As the companies rightly point out, many of today’s industrial IoT solutions rely on “complex, proprietary systems that create data silos and slow productivity.” Who wouldn’t want to “standardize data models that enable analytics and machine learning scenarios” and “accelerate future industrial IoT developments, shorten time to value, and drive production efficiencies while addressing common industrial challenges”?
|
||||
|
||||
But before you get too excited, let’s talk about a key word in the effort: open. As Scott Guthrie, executive vice president of Microsoft Cloud + AI Group, said in a statement, "Our commitment to building an open community will create new opportunities for collaboration across the entire manufacturing value chain."
|
||||
|
||||
### The Open Manufacturing Platform is open only to Microsoft Azure
|
||||
|
||||
However, that will happen as long as all that collaboration occurs in Microsoft Azure. I’m not saying Azure isn’t up to the task, but it’s hardly the only (or even the leading) cloud platform interested in the industrial IoT. Putting everything in Azure might be an issue to those potential OMP partners. It’s an “open” question as to how many companies already invested in Amazon Web Services (AWS) or the Google Cloud Platform (GCP) will be willing to make the switch or go multi-cloud just to take advantage of the OMP.
|
||||
|
||||
My guess is that Microsoft and BMW won’t have too much trouble meeting their initial goals for the OMP. It shouldn’t be that hard to get a handful of existing Azure customers to come up with 15 use cases leveraging advances in analytics, artificial intelligence (AI), and digital feedback loops. (As an example, the companies cited the autonomous transport systems in BMW’s factory in Regensburg, Germany, part of the more than 3,000 machines, robots and transport systems connected with the BMW Group’s IoT platform, which — naturally — is built on Microsoft Azure's cloud.)
|
||||
|
||||
### Will non-Azure users jump on board the OMP?
|
||||
|
||||
The question is whether tying all this to a single cloud provider will affect the effort to attract enough new companies — including companies not currently using Azure — to establish a truly viable open platform?
|
||||
|
||||
Perhaps [Stacey Higginbotham at Stacy on IoT put it best][7]:
|
||||
|
||||
> “What they really launched is a reference design for manufacturers to work from.”
|
||||
|
||||
That’s not nothing, of course, but it’s a lot less ambitious than building a new industrial IoT platform. And it may not easily fulfill the vision of a community working together to create shared solutions that benefit everyone.
|
||||
|
||||
**[ Now read this:[Why are IoT platforms so darn confusing?][8] ]**
|
||||
|
||||
Join the Network World communities on [Facebook][9] and [LinkedIn][10] to comment on topics that are top of mind.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.networkworld.com/article/3387642/the-microsoftbmw-iot-open-manufacturing-platform-might-not-be-so-open.html#tk.rss_all
|
||||
|
||||
作者：[Fredric Paul][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://www.networkworld.com/author/Fredric-Paul/
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://images.techhive.com/images/article/2017/01/20170107_105344-100702818-large.jpg
|
||||
[2]: https://www.hannovermesse.de/home
|
||||
[3]: https://www.prnewswire.co.uk/news-releases/microsoft-and-the-bmw-group-launch-the-open-manufacturing-platform-859672858.html
|
||||
[4]: https://en.wikipedia.org/wiki/Industry_4.0
|
||||
[5]: https://www.networkworld.com/article/3384378/an-inside-look-at-tempo-automations-iiot-powered-smart-factory.html
|
||||
[6]: https://www.networkworld.com/newsletters/signup.html
|
||||
[7]: https://mailchi.mp/iotpodcast/stacey-on-iot-industrial-iot-reminds-me-of-apples-ecosystem?e=6bf9beb394
|
||||
[8]: https://www.networkworld.com/article/3336166/why-are-iot-platforms-so-darn-confusing.html
|
||||
[9]: https://www.facebook.com/NetworkWorld/
|
||||
[10]: https://www.linkedin.com/company/network-world
|
||||
@@ -0,0 +1,204 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (What it takes to become a blockchain developer)
|
||||
[#]: via: (https://opensource.com/article/19/4/blockchain-career-developer)
|
||||
[#]: author: (Joseph Mugo https://opensource.com/users/mugo)
|
||||
|
||||
What it takes to become a blockchain developer
|
||||
======
|
||||
If you’ve been considering a career in blockchain development, the time
|
||||
to get your foot in the door is now. Here's how to get started.
|
||||
![][1]
|
||||
|
||||
The past decade has been an interesting time for the development of decentralized technologies. Before 2009, the progress was slow and without any clear direction until Satoshi Nakamoto created and deployed Bitcoin. That brought blockchain, the record-keeping technology behind Bitcoin, into the limelight.
|
||||
|
||||
Since then, we've seen blockchain revolutionize various concepts that we used to take for granted, such as monitoring supply chains, [creating digital identities,][2] [tracking jewelry][3], and [managing shipping systems.][4] Companies such as IBM and Samsung are at the forefront of blockchain as the underlying infrastructure for the next wave of tech innovation. There is no doubt that blockchain's role will grow in the years to come.
|
||||
|
||||
Thus, it's no surprise that there's a high demand for blockchain developers. LinkedIn put "blockchain developers" at the top of its 2018 [emerging jobs report][5] with an expected 33-fold growth. The freelancing site Upwork also released a report showing that blockchain was one of the [fastest growing skills][6] out of more than 5,000 in its index.
|
||||
|
||||
Describing the internet in 2003, [Jeff Bezos said][7], "we are at the 1908 Hurley washing machine stage." The same can be said about blockchain today. The industry is busy building its foundation. If you've been considering a career as a blockchain developer, the time to get your foot in the door is now.
|
||||
|
||||
However, you may not know where to start. It can be frustrating to go through countless blog posts and white papers or messy Slack channels when trying to find your footing. This article is a report on what I learned when contemplating whether I should become a blockchain developer. I'll approach it from the basics, with resources for each topic you need to master to be industry-ready.
|
||||
|
||||
### Technical fundamentals
|
||||
|
||||
Although you're won't be expected to build a blockchain from scratch, you need to be skilled enough to handle the duties of blockchain development. A bachelor's degree in computer science or information security is required. You also need to have some fundamentals in data structures, cryptography, and networking and distributed systems.
|
||||
|
||||
#### Data structures
|
||||
|
||||
The complexity of blockchain requires a solid understanding of data structures. At the core, a distributed ledger is like a network of replicated databases, only it stores information in blocks rather than tables. The blocks are also cryptographically secured to ensure their integrity every time a block is added.
|
||||
|
||||
For this reason, you have to know how common data structures, such as binary search trees, hash maps, graphs, and linked lists, work. It's even better if you can build them from scratch.
|
||||
|
||||
This [GitHub repository][8] contains all information newbies need to learn data structures and algorithms. Common languages such as Python, Java, Scala, C, C-Sharp, and C++ are featured.
|
||||
|
||||
#### Cryptography
|
||||
|
||||
Cryptography is the foundation of blockchain; it is what makes cryptocurrencies work. The Bitcoin blockchain employs public-key cryptography to create digital signatures and hash functions. You might be discouraged if you don't have a strong math background, but Stanford offers [a free course][9] that's perfect for newbies. You'll learn about authenticated encryption, message integrity, and block ciphers.
|
||||
|
||||
You should also study [RSA][10], which doesn't require a strong background in mathematics, and look at [ECDSA][11] (elliptic curve cryptography).
|
||||
|
||||
And don't forget [cryptographic hash functions][12]. They are the equations that enable most forms of encryptions on the internet. They keep payments secure on e-commerce sites and are the core mechanism behind the HTTPS protocol. There's extensive use of cryptographic hash functions in blockchain.
|
||||
|
||||
#### Networking and distributed systems
|
||||
|
||||
Build a good foundation in understanding how distributed ledgers work. Also understand how peer-to-peer networks work, which translates to a good foundation in computer networks, from networking topologies to routing.
|
||||
|
||||
In blockchain, the processing power is harnessed from connected computers. For seamless recording and interchange of information between these devices, you need to understand about [Byzantine fault-tolerant consensus][13], which is a key security feature in blockchain. You don't need to know everything; an understanding of how distributed systems work is good enough.
|
||||
|
||||
Stanford has a free, self-paced [course on computer networking][14] if you need to start from scratch. You can also consult this list of [awesome material on distributed systems][15].
|
||||
|
||||
### Cryptonomics
|
||||
|
||||
We've covered some of the most important technical bits. It's time to talk about the economics of this industry. Although cryptocurrencies don't have central banks to monitor the money supply or keep crypto companies in check, it's essential to understand the economic structures woven around them.
|
||||
|
||||
You'll need to understand game theory, the ideal mathematical framework for modeling scenarios in which conflicts of interest exist among involved parties. Take a look at Michael Karnjanaprakorn's [Beginner's Guide to Game Theory][16]. It's lucid and well explained.
|
||||
|
||||
You also need to understand what affects currency valuation and the various monetary policies that affect cryptocurrencies. Here are some books you can refer to:
|
||||
|
||||
* _[The Business Blockchain: Promise, Practice, and Application of the Next Internet Technology][17]_ by William Mougayar
|
||||
* _[Blockchain: Blueprint for the New Economy][18]_ by Melanie Swan
|
||||
* _[Blockchain: The Blockchain For Beginners Guide to Blockchain Technology and Leveraging Blockchain Programming][19]_ by Josh Thompsons
|
||||
|
||||
|
||||
|
||||
Depending on how skilled you are, you won't need to go through all those materials. But once you're done, you'll understand the fundamentals of blockchain. Then you can dive into the good stuff.
|
||||
|
||||
### Smart contracts
|
||||
|
||||
A [smart contract][20] is a program that runs on the blockchain once a transaction is complete to enhance blockchain's capabilities.
|
||||
|
||||
Unlike traditional judicial systems, smart contracts are enforced automatically and impartially. There are also no middlemen, so you don't need a lawyer to oversee a transaction.
|
||||
|
||||
As smart contracts get more complex, they become harder to secure. You need to be aware of every possible way a smart contract can be executed and ensure that it does what is expected. At the moment, not many developers can properly optimize and audit smart contracts.
|
||||
|
||||
### Decentralized applications
|
||||
|
||||
Decentralized applications (DApps) are software built on blockchains. As a blockchain developer, there are several platforms where you can build a DApp. Here are some of them:
|
||||
|
||||
#### Ethereum
|
||||
|
||||
Ethereum is Vitalik Buterin's brainchild. It went live in 2015 and is one of the most popular development platforms. Ether is the cryptocurrency that fuels the Ethereum.
|
||||
|
||||
It has its own language called Solidity, which is similar to C++ and JavaScript. If you've got any experience with either, you'll pick it up easily.
|
||||
|
||||
One thing that makes Solidity unique is that it is smart-contract oriented.
|
||||
|
||||
#### NEO
|
||||
|
||||
Originally known as Antshares, NEO was founded by Erik Zhang and Da Hongfei in 2014. It became NEO in 2017. Unlike Ethereum, it's not limited to one language. You can use different programming languages to build your DApps on NEO, including C# and Java. Experienced users can easily start building DApps on NEO. It's focused on providing platforms for future digital businesses.
|
||||
|
||||
Consider NEO if you have applications that will need to process lots of transactions per second. However, it works closely with the Chinese government and follows Chinese business regulations.
|
||||
|
||||
#### EOS
|
||||
|
||||
EOS blockchain aims to be a decentralized operating system that can support industrial-scale applications. It's basically like Ethereum, but with faster transaction speeds and more scalable.
|
||||
|
||||
#### Hyperledger
|
||||
|
||||
Hyperledger is an open source collaborative platform that was created to develop cross-industry blockchain technologies. The Linux Foundation hosts Hyperledger as a hub for open industrial blockchain development.
|
||||
|
||||
### Learning resources
|
||||
|
||||
Here are some courses and other resources that'll help make you an industry-ready blockchain developer.
|
||||
|
||||
* The University of Buffalo and The State University of New York have a [blockchain specialization course][21] that also teaches smart contracts. You can complete it in two months if you put in 10 hours per week. You'll learn about designing and implementing smart contracts and various methods for developing decentralized applications on blockchain.
|
||||
* [DApps for Beginners][22] offers tutorials and other information to get you started on creating decentralized apps on the Ethereum blockchain. You'll need to know JavaScript, and knowledge of C++ is an added advantage.
|
||||
* IBM also offers [Blockchain for Developers][23], where you'll work with IBM's private blockchain and build smart contracts using the [Hyperledger Fabric][24].
|
||||
* For $3,500 you can enroll in MIT's online [Blockchain Technologies: Business Innovation and Application][25] program, which examines blockchain from an economic perspective. You need deep pockets for this one; it's meant for executives who want to know how blockchain can be used in their organizations.
|
||||
* If you're willing to commit 10 hours per week, Udacity's [Blockchain Developer Nanodegree][26] can prepare you to become an industry-ready blockchain developer in six months. Before enrolling, you should have some experience in object-oriented programming. You should also have developed the frontend and backend of a web application with JavaScript. And you're required to have used a remote API to create and consume data. You'll work with Bitcoin and Ethereum protocols to build projects for real-world applications.
|
||||
* If you need to shore up your foundations, you may be interested in the Open Source Society University's wildly popular and [free computer science curriculum][27].
|
||||
* You can read a variety of articles about [blockchain in open source][28] on [Opensource.com][29].
|
||||
|
||||
|
||||
|
||||
### Types of blockchain development
|
||||
|
||||
What does a blockchain developer really do? It doesn't involve building a blockchain from scratch. Depending on the organization you work for, here are some of the categories that blockchain developers fall under.
|
||||
|
||||
#### Backend developers
|
||||
|
||||
In this case, the developer is responsible for:
|
||||
|
||||
* Designing and developing APIs for blockchain integration
|
||||
* Doing performance testing and deployment
|
||||
* Gathering requirements and working side-by-side with other developers and designers to design software
|
||||
* Providing technical support
|
||||
|
||||
|
||||
|
||||
#### Blockchain-specific
|
||||
|
||||
Blockchain developers and project managers fall under this category. Their main roles include:
|
||||
|
||||
* Developing and maintaining decentralized applications
|
||||
* Supervising and planning blockchain projects
|
||||
* Advising companies on how to structure initial coin offerings (ICOs)
|
||||
* Understanding what a company needs and creating apps that address those needs
|
||||
* For project managers, organizing training for employees
|
||||
|
||||
|
||||
|
||||
#### Smart-contract engineers
|
||||
|
||||
This type of developer is required to know a smart-contract language like Solidity, Python, or Go. Their main roles include:
|
||||
|
||||
* Auditing and developing smart contracts
|
||||
* Meeting with users and buyers
|
||||
* Understanding business flow and security to ensure there are no loopholes in smart contracts
|
||||
* Doing end-to-end business process testing
|
||||
|
||||
|
||||
|
||||
### The state of the industry
|
||||
|
||||
There's a wide base of knowledge to help you become a blockchain developer. If you're interested in joining the field, it's an opportunity for you to make a difference by pioneering the next wave of tech innovations. It pays very well and is in high demand. There's also a wide community you can join to help you gain entry as an actual developer, including [Ethereum Stack Exchange][30] and meetup events around the world.
|
||||
|
||||
The banking sector, the insurance industry, governments, and retail industries are some of the sectors where blockchain developers can work. If you're willing to work for it, being a blockchain developer is an excellent career choice. Currently, the need outpaces available talent by far.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/19/4/blockchain-career-developer
|
||||
|
||||
作者：[Joseph Mugo][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://opensource.com/users/mugo
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/EDU_UnspokenBlockers_1110_A.png?itok=x8A9mqVA
|
||||
[2]: https://www.fool.com/investing/2018/02/16/this-is-really-happening-microsoft-is-developing-b.aspx
|
||||
[3]: https://www.engadget.com/2018/04/26/ibm-blockchain-jewelry-provenance/
|
||||
[4]: https://www.engadget.com/2018/04/16/samsung-blockchain-based-global-shipping-system/
|
||||
[5]: https://economicgraph.linkedin.com/research/linkedin-2018-emerging-jobs-report
|
||||
[6]: https://www.upwork.com/blog/2018/05/fastest-growing-skills-upwork-q1-2018/
|
||||
[7]: https://www.wsj.com/articles/SB104690855395981400
|
||||
[8]: https://github.com/TheAlgorithms
|
||||
[9]: https://www.coursera.org/learn/crypto
|
||||
[10]: https://en.wikipedia.org/wiki/RSA_(cryptosystem)
|
||||
[11]: https://en.wikipedia.org/wiki/Elliptic_Curve_Digital_Signature_Algorithm
|
||||
[12]: https://komodoplatform.com/cryptographic-hash-function/
|
||||
[13]: https://en.wikipedia.org/wiki/Byzantine_fault
|
||||
[14]: https://lagunita.stanford.edu/courses/Engineering/Networking-SP/SelfPaced/about
|
||||
[15]: https://github.com/theanalyst/awesome-distributed-systems
|
||||
[16]: https://hackernoon.com/beginners-guide-to-game-theory-31e3e6adcec9
|
||||
[17]: https://www.amazon.com/dp/B01EIGP8HG/
|
||||
[18]: https://www.amazon.com/Blockchain-Blueprint-Economy-Melanie-Swan/dp/1491920491
|
||||
[19]: https://www.amazon.com/Blockchain-Beginners-Technology-Leveraging-Programming-ebook/dp/B0711RN8KJ
|
||||
[20]: https://lifeinpaces.com/2019/03/04/ethereum-smart-contracts-how-do-they-work/
|
||||
[21]: https://www.coursera.org/specializations/blockchain?aid=true
|
||||
[22]: https://dappsforbeginners.wordpress.com/
|
||||
[23]: https://developer.ibm.com/tutorials/cl-ibm-blockchain-101-quick-start-guide-for-developers-bluemix-trs/#start
|
||||
[24]: https://www.hyperledger.org/projects/fabric
|
||||
[25]: https://executive.mit.edu/openenrollment/program/blockchain-technologies-business-innovation-and-application-self-paced-online/#.XJSk-CgzbRY
|
||||
[26]: https://www.udacity.com/course/blockchain-developer-nanodegree--nd1309
|
||||
[27]: https://github.com/ossu/computer-science
|
||||
[28]: https://opensource.com/tags/blockchain
|
||||
[29]: http://Opensource.com
|
||||
[30]: https://ethereum.stackexchange.com/
|
||||
267
sources/tech/20190409 Working with variables on Linux.md
Normal file
267
sources/tech/20190409 Working with variables on Linux.md
Normal file
@@ -0,0 +1,267 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (Working with variables on Linux)
|
||||
[#]: via: (https://www.networkworld.com/article/3387154/working-with-variables-on-linux.html#tk.rss_all)
|
||||
[#]: author: (Sandra Henry-Stocker https://www.networkworld.com/author/Sandra-Henry_Stocker/)
|
||||
|
||||
Working with variables on Linux
|
||||
======
|
||||
Variables often look like $var, but they also look like $1, $*, $? and $$. Let's take a look at what all these $ values can tell you.
|
||||
![Mike Lawrence \(CC BY 2.0\)][1]
|
||||
|
||||
A lot of important values are stored on Linux systems in what we call “variables,” but there are actually several types of variables and some interesting commands that can help you work with them. In a previous post, we looked at [environment variables][2] and where they are defined. In this post, we're going to look at variables that are used on the command line and within scripts.
|
||||
|
||||
### User variables
|
||||
|
||||
While it's quite easy to set up a variable on the command line, there are a few interesting tricks. To set up a variable, all you need to do is something like this:
|
||||
|
||||
```
|
||||
$ myvar=11
|
||||
$ myvar2="eleven"
|
||||
```
|
||||
|
||||
To display the values, you simply do this:
|
||||
|
||||
```
|
||||
$ echo $myvar
|
||||
11
|
||||
$ echo $myvar2
|
||||
eleven
|
||||
```
|
||||
|
||||
You can also work with your variables. For example, to increment a numeric variable, you could use any of these commands:
|
||||
|
||||
```
|
||||
$ myvar=$((myvar+1))
|
||||
$ echo $myvar
|
||||
12
|
||||
$ ((myvar=myvar+1))
|
||||
$ echo $myvar
|
||||
13
|
||||
$ ((myvar+=1))
|
||||
$ echo $myvar
|
||||
14
|
||||
$ ((myvar++))
|
||||
$ echo $myvar
|
||||
15
|
||||
$ let "myvar=myvar+1"
|
||||
$ echo $myvar
|
||||
16
|
||||
$ let "myvar+=1"
|
||||
$ echo $myvar
|
||||
17
|
||||
$ let "myvar++"
|
||||
$ echo $myvar
|
||||
18
|
||||
```
|
||||
|
||||
With some of these, you can add more than 1 to a variable's value. For example:
|
||||
|
||||
```
|
||||
$ myvar0=0
|
||||
$ ((myvar0++))
|
||||
$ echo $myvar0
|
||||
1
|
||||
$ ((myvar0+=10))
|
||||
$ echo $myvar0
|
||||
11
|
||||
```
|
||||
|
||||
With all these choices, you'll probably find at least one that is easy to remember and convenient to use.
|
||||
|
||||
You can also _unset_ a variable — basically undefining it.
|
||||
|
||||
```
|
||||
$ unset myvar
|
||||
$ echo $myvar
|
||||
```
|
||||
|
||||
Another interesting option is that you can set up a variable and make it **read-only**. In other words, once set to read-only, its value cannot be changed (at least not without some very tricky command line wizardry). That means you can't unset it either.
|
||||
|
||||
```
|
||||
$ readonly myvar3=1
|
||||
$ echo $myvar3
|
||||
1
|
||||
$ ((myvar3++))
|
||||
-bash: myvar3: readonly variable
|
||||
$ unset myvar3
|
||||
-bash: unset: myvar3: cannot unset: readonly variable
|
||||
```
|
||||
|
||||
You can use any of those setting and incrementing options for assigning and manipulating variables within scripts, but there are also some very useful _internal variables_ for working within scripts. Note that you can't reassign their values or increment them.
|
||||
|
||||
### Internal variables
|
||||
|
||||
There are quite a few variables that can be used within scripts to evaluate arguments and display information about the script itself.
|
||||
|
||||
* $1, $2, $3 etc. represent the first, second, third, etc. arguments to the script.
|
||||
* $# represents the number of arguments.
|
||||
* $* represents the string of arguments.
|
||||
* $0 represents the name of the script itself.
|
||||
* $? represents the return code of the previously run command (0=success).
|
||||
* $$ shows the process ID for the script.
|
||||
* $PPID shows the process ID for your shell (the parent process for the script).
|
||||
|
||||
|
||||
|
||||
Some of these variables also work on the command line but show related information:
|
||||
|
||||
* $0 shows the name of the shell you're using (e.g., -bash).
|
||||
* $$ shows the process ID for your shell.
|
||||
* $PPID shows the process ID for your shell's parent process (for me, this is sshd).
|
||||
|
||||
|
||||
|
||||
If we throw all of these variables into a script just to see the results, we might do this:
|
||||
|
||||
```
|
||||
#!/bin/bash
|
||||
|
||||
echo $0
|
||||
echo $1
|
||||
echo $2
|
||||
echo $#
|
||||
echo $*
|
||||
echo $?
|
||||
echo $$
|
||||
echo $PPID
|
||||
```
|
||||
|
||||
When we call this script, we'll see something like this:
|
||||
|
||||
```
|
||||
$ tryme one two three
|
||||
/home/shs/bin/tryme <== script name
|
||||
one <== first argument
|
||||
two <== second argument
|
||||
3 <== number of arguments
|
||||
one two three <== all arguments
|
||||
0 <== return code from previous echo command
|
||||
10410 <== script's process ID
|
||||
10109 <== parent process's ID
|
||||
```
|
||||
|
||||
If we check the process ID of the shell once the script is done running, we can see that it matches the PPID displayed within the script:
|
||||
|
||||
```
|
||||
$ echo $$
|
||||
10109 <== shell's process ID
|
||||
```
|
||||
|
||||
Of course, we're more likely to use these variables in considerably more useful ways than simply displaying their values. Let's check out some ways we might do this.
|
||||
|
||||
Checking to see if arguments have been provided:
|
||||
|
||||
```
|
||||
if [ $# == 0 ]; then
|
||||
echo "$0 filename"
|
||||
exit 1
|
||||
fi
|
||||
```
|
||||
|
||||
Checking to see if a particular process is running:
|
||||
|
||||
```
|
||||
ps -ef | grep apache2 > /dev/null
|
||||
if [ $? != 0 ]; then
|
||||
echo Apache is not running
|
||||
exit
|
||||
fi
|
||||
```
|
||||
|
||||
Verifying that a file exists before trying to access it:
|
||||
|
||||
```
|
||||
if [ $# -lt 2 ]; then
|
||||
echo "Usage: $0 lines filename"
|
||||
exit 1
|
||||
fi
|
||||
|
||||
if [ ! -f $2 ]; then
|
||||
echo "Error: File $2 not found"
|
||||
exit 2
|
||||
else
|
||||
head -$1 $2
|
||||
fi
|
||||
```
|
||||
|
||||
And in this little script, we check if the correct number of arguments have been provided, if the first argument is numeric, and if the second argument is an existing file.
|
||||
|
||||
```
|
||||
#!/bin/bash
|
||||
|
||||
if [ $# -lt 2 ]; then
|
||||
echo "Usage: $0 lines filename"
|
||||
exit 1
|
||||
fi
|
||||
|
||||
if [[ $1 != [0-9]* ]]; then
|
||||
echo "Error: $1 is not numeric"
|
||||
exit 2
|
||||
fi
|
||||
|
||||
if [ ! -f $2 ]; then
|
||||
echo "Error: File $2 not found"
|
||||
exit 3
|
||||
else
|
||||
echo top of file
|
||||
head -$1 $2
|
||||
fi
|
||||
```
|
||||
|
||||
### Renaming variables
|
||||
|
||||
When writing a complicated script, it's often useful to assign names to the script's arguments rather than continuing to refer to them as $1, $2, and so on. By the 35th line, someone reading your script might have forgotten what $2 represents. It will be a lot easier on that person if you assign an important parameter's value to $filename or $numlines.
|
||||
|
||||
```
|
||||
#!/bin/bash
|
||||
|
||||
if [ $# -lt 2 ]; then
|
||||
echo "Usage: $0 lines filename"
|
||||
exit 1
|
||||
else
|
||||
numlines=$1
|
||||
filename=$2
|
||||
fi
|
||||
|
||||
if [[ $numlines != [0-9]* ]]; then
|
||||
echo "Error: $numlines is not numeric"
|
||||
exit 2
|
||||
fi
|
||||
|
||||
if [ ! -f $ filename]; then
|
||||
echo "Error: File $filename not found"
|
||||
exit 3
|
||||
else
|
||||
echo top of file
|
||||
head -$numlines $filename
|
||||
fi
|
||||
```
|
||||
|
||||
Of course, this example script does nothing more than run the head command to show the top X lines in a file, but it is meant to show how internal parameters can be used within scripts to help ensure the script runs well or fails with at least some clarity.
|
||||
|
||||
**[ Watch Sandra Henry-Stocker's Two-Minute Linux Tips[to learn how to master a host of Linux commands][3] ]**
|
||||
|
||||
Join the Network World communities on [Facebook][4] and [LinkedIn][5] to comment on topics that are top of mind.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.networkworld.com/article/3387154/working-with-variables-on-linux.html#tk.rss_all
|
||||
|
||||
作者：[Sandra Henry-Stocker][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://www.networkworld.com/author/Sandra-Henry_Stocker/
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://images.idgesg.net/images/article/2019/04/variable-key-keyboard-100793080-large.jpg
|
||||
[2]: https://www.networkworld.com/article/3385516/how-to-manage-your-linux-environment.html
|
||||
[3]: https://www.youtube.com/playlist?list=PL7D2RMSmRO9J8OTpjFECi8DJiTQdd4hua
|
||||
[4]: https://www.facebook.com/NetworkWorld/
|
||||
[5]: https://www.linkedin.com/company/network-world
|
||||
@@ -0,0 +1,136 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (How to enable serverless computing in Kubernetes)
|
||||
[#]: via: (https://opensource.com/article/19/4/enabling-serverless-kubernetes)
|
||||
[#]: author: (Daniel Oh (Red Hat, Community Moderator) https://opensource.com/users/daniel-oh/users/daniel-oh)
|
||||
|
||||
How to enable serverless computing in Kubernetes
|
||||
======
|
||||
Knative is a faster, easier way to develop serverless applications on
|
||||
Kubernetes platforms.
|
||||
![Kubernetes][1]
|
||||
|
||||
In the first two articles in this series about using serverless on an open source platform, I described [how to get started with serverless platforms][2] and [how to write functions][3] in popular languages and build components using containers on Apache OpenWhisk.
|
||||
|
||||
Here in the third article, I'll walk you through enabling serverless in your [Kubernetes][4] environment. Kubernetes is the most popular platform to manage serverless workloads and microservice application containers and uses a finely grained deployment model to process workloads more quickly and easily.
|
||||
|
||||
Keep in mind that serverless not only helps you reduce infrastructure management while utilizing a consumption model for actual service use but also provides many capabilities of what the cloud platform serves. There are many serverless or FaaS (Function as a Service) platforms, but Kuberenetes is the first-class citizen for building a serverless platform because there are more than [13 serverless or FaaS open source projects][5] based on Kubernetes.
|
||||
|
||||
However, Kubernetes won't allow you to build, serve, and manage app containers for your serverless workloads in a native way. For example, if you want to build a [CI/CD pipeline][6] on Kubernetes to build, test, and deploy cloud-native apps from source code, you need to use your own release management tool and integrate it with Kubernetes.
|
||||
|
||||
Likewise, it's difficult to use Kubernetes in combination with serverless computing unless you use an independent serverless or FaaS platform built on Kubernetes, such as [Apache OpenWhisk][7], [Riff][8], or [Kubeless][9]. More importantly, the Kubernetes environment is still difficult for developers to learn the features of how it deals with serverless workloads from cloud-native apps.
|
||||
|
||||
### Knative
|
||||
|
||||
[Knative][10] was born for developers to create serverless experiences natively without depending on extra serverless or FaaS frameworks and many custom tools. Knative has three primary components—[Build][11], [Serving][12], and [Eventing][13]—for addressing common patterns and best practices for developing serverless applications on Kubernetes platforms.
|
||||
|
||||
To learn more, let's go through the usual development process for using Knative to increase productivity and solve Kubernetes' difficulties from the developer's point of view.
|
||||
|
||||
**Step 1:** Generate your cloud-native application from scratch using [Spring Initializr][14] or [Thorntail Project Generator][15]. Begin implementing your business logic using the [12-factor app methodology][16], and you might also do assembly testing to see if the function works correctly in many local testing tools.
|
||||
|
||||
![Spring Initializr screenshot][17] | ![Thorntail Project Generator screenshot][18]
|
||||
---|---
|
||||
|
||||
**Step 2:** Build container images from your source code repositories via the Knative Build component. You can define multiple steps, such as installing dependencies, running integration testing, and pushing container images to your secured image registry for using existing Kubernetes primitives. More importantly, Knative Build makes developers' daily work easier and simpler—"boring but difficult." Here's an example of the Build YAML:
|
||||
|
||||
|
||||
```
|
||||
apiVersion: build.knative.dev/v1alpha1
|
||||
kind: Build
|
||||
metadata:
|
||||
name: docker-build
|
||||
spec:
|
||||
serviceAccountName: build-bot
|
||||
source:
|
||||
git:
|
||||
revision: master
|
||||
url: <https://github.com/redhat-developer-demos/knative-tutorial-event-greeter.git>
|
||||
steps:
|
||||
\- args:
|
||||
\- --context=/workspace/java/springboot
|
||||
\- --dockerfile=/workspace/java/springboot/Dockerfile
|
||||
\- --destination=docker.io/demo/event-greeter:0.0.1
|
||||
env:
|
||||
\- name: DOCKER_CONFIG
|
||||
value: /builder/home/.docker
|
||||
image: gcr.io/kaniko-project/executor
|
||||
name: docker-push
|
||||
```
|
||||
|
||||
**Step 3:** Deploy and serve your container applications as serverless workloads via the Knative Serving component. This step shows the beauty of Knative in terms of automatically scaling up your serverless containers on Kubernetes then scaling them down to zero if there is no request to the containers for a specific period (e.g., two minutes). More importantly, [Istio][19] will automatically address ingress and egress networking traffic of serverless workloads in multiple, secure ways. Here's an example of the Serving YAML:
|
||||
|
||||
|
||||
```
|
||||
apiVersion: serving.knative.dev/v1alpha1
|
||||
kind: Service
|
||||
metadata:
|
||||
name: greeter
|
||||
spec:
|
||||
runLatest:
|
||||
configuration:
|
||||
revisionTemplate:
|
||||
spec:
|
||||
container:
|
||||
image: dev.local/rhdevelopers/greeter:0.0.1
|
||||
```
|
||||
|
||||
**Step 4:** Bind running serverless containers to a variety of eventing platforms, such as SaaS, FaaS, and Kubernetes, via Knative's Eventing component. In this step, you can define event channels and subscriptions, which are delivered to your services via a messaging platform such as [Apache Kafka][20] or [NATS streaming][21]. Here's an example of the Event sourcing YAML:
|
||||
|
||||
|
||||
```
|
||||
apiVersion: sources.eventing.knative.dev/v1alpha1
|
||||
kind: CronJobSource
|
||||
metadata:
|
||||
name: test-cronjob-source
|
||||
spec:
|
||||
schedule: "* * * * *"
|
||||
data: '{"message": "Event sourcing!!!!"}'
|
||||
sink:
|
||||
apiVersion: eventing.knative.dev/v1alpha1
|
||||
kind: Channel
|
||||
name: ch-event-greeter
|
||||
```
|
||||
|
||||
### Conclusion
|
||||
|
||||
Developing with Knative will save a lot of time in building serverless applications in the Kubernetes environment. It can also make developers' jobs easier by focusing on developing serverless applications, functions, or cloud-native containers.
|
||||
|
||||
* * *
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/19/4/enabling-serverless-kubernetes
|
||||
|
||||
作者：[Daniel Oh (Red Hat, Community Moderator)][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://opensource.com/users/daniel-oh/users/daniel-oh
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/kubernetes.png?itok=PqDGb6W7 (Kubernetes)
|
||||
[2]: https://opensource.com/article/18/11/open-source-serverless-platforms
|
||||
[3]: https://opensource.com/article/18/11/developing-functions-service-apache-openwhisk
|
||||
[4]: https://kubernetes.io/
|
||||
[5]: https://landscape.cncf.io/format=serverless
|
||||
[6]: https://opensource.com/article/18/8/what-cicd
|
||||
[7]: https://openwhisk.apache.org/
|
||||
[8]: https://projectriff.io/
|
||||
[9]: https://kubeless.io/
|
||||
[10]: https://cloud.google.com/knative/
|
||||
[11]: https://github.com/knative/build
|
||||
[12]: https://github.com/knative/serving
|
||||
[13]: https://github.com/knative/eventing
|
||||
[14]: https://start.spring.io/
|
||||
[15]: https://thorntail.io/generator/
|
||||
[16]: https://12factor.net/
|
||||
[17]: https://opensource.com/sites/default/files/uploads/spring_300.png (Spring Initializr screenshot)
|
||||
[18]: https://opensource.com/sites/default/files/uploads/springboot_300.png (Thorntail Project Generator screenshot)
|
||||
[19]: https://istio.io/
|
||||
[20]: https://kafka.apache.org/
|
||||
[21]: https://nats.io/
|
||||
@@ -0,0 +1,101 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (How we built a Linux desktop app with Electron)
|
||||
[#]: via: (https://opensource.com/article/19/4/linux-desktop-electron)
|
||||
[#]: author: (Nils Ganther https://opensource.com/users/nils-ganther)
|
||||
|
||||
How we built a Linux desktop app with Electron
|
||||
======
|
||||
A story of building an open source email service that runs natively on
|
||||
Linux desktops, thanks to the Electron framework.
|
||||
![document sending][1]
|
||||
|
||||
[Tutanota][2] is a secure, open source email service that's been available as an app for the browser, iOS, and Android. The client code is published under GPLv3 and the Android app is available on [F-Droid][3] to enable everyone to use a completely Google-free version.
|
||||
|
||||
Because Tutanota focuses on open source and develops on Linux clients, we wanted to release a desktop app for Linux and other platforms. Being a small team, we quickly ruled out building native apps for Linux, Windows, and MacOS and decided to adapt our app using [Electron][4].
|
||||
|
||||
Electron is the go-to choice for anyone who wants to ship visually consistent, cross-platform applications, fast—especially if there's already a web app that needs to be freed from the shackles of the browser API. Tutanota is exactly such a case.
|
||||
|
||||
Tutanota is based on [SystemJS][5] and [Mithril][6] and aims to offer simple, secure email communications for everybody. As such, it has to provide a lot of the standard features users expect from any email client.
|
||||
|
||||
Some of these features, like basic push notifications, search for text and contacts, and support for two-factor authentication are easy to offer in the browser thanks to modern APIs and standards. Other features (such as automatic backups or IMAP support without involving our servers) need less-restricted access to system resources, which is exactly what the Electron framework provides.
|
||||
|
||||
While some criticize Electron as "just a basic wrapper," it has obvious benefits:
|
||||
|
||||
* Electron enables you to adapt a web app quickly for Linux, Windows, and MacOS desktops. In fact, most Linux desktop apps are built with Electron.
|
||||
* Electron enables you to easily bring the desktop client to feature parity with the web app.
|
||||
* Once you've published the desktop app, you can use free development capacity to add desktop-specific features that enhance usability and security.
|
||||
* And last but certainly not least, it's a great way to make the app feel native and integrated into the user's system while maintaining its identity.
|
||||
|
||||
|
||||
|
||||
### Meeting users' needs
|
||||
|
||||
At Tutanota, we do not rely on big investor money, rather we are a community-driven project. We grow our team organically based on the increasing number of users upgrading to our freemium service's paid plans. Listening to what users want is not only important to us, it is essential to our success.
|
||||
|
||||
Offering a desktop client was users' [most-wanted feature][7] in Tutanota, and we are proud that we can now offer free beta desktop clients to all of our users. (We also implemented another highly requested feature—[search on encrypted data][8]—but that's a topic for another time.)
|
||||
|
||||
We liked the idea of providing users with signed versions of Tutanota and enabling functions that are impossible in the browser, such as push notifications via a background process. Now we plan to add more desktop-specific features, such as IMAP support without depending on our servers to act as a proxy, automatic backups, and offline availability.
|
||||
|
||||
We chose Electron because its combination of Chromium and Node.js promised to be the best fit for our small development team, as it required only minimal changes to our web app. It was particularly helpful to use the browser APIs for everything as we got started, slowly replacing those components with more native versions as we progressed. This approach was especially handy with attachment downloads and notifications.
|
||||
|
||||
### Tuning security
|
||||
|
||||
We were aware that some people cite security problems with Electron, but we found Electron's options for fine-tuning access in the web app quite satisfactory. You can use resources like the Electron's [security documentation][9] and Luca Carettoni's [Electron Security Checklist][10] to help prevent catastrophic mishaps with untrusted content in your web app.
|
||||
|
||||
### Achieving feature parity
|
||||
|
||||
The Tutanota web client was built from the start with a solid protocol for interprocess communication. We utilize web workers to keep user interface (UI) rendering responsive while encrypting and requesting data. This came in handy when we started implementing our mobile apps, which use the same protocol to communicate between the native part and the web view.
|
||||
|
||||
That's why when we started building the desktop clients, a lot of bindings for things like native push notifications, opening mailboxes, and working with the filesystem were already there, so only the native (node) side had to be implemented.
|
||||
|
||||
Another convenience was our build process using the [Babel transpiler][11], which allows us to write the entire codebase in modern ES6 JavaScript and mix-and-match utility modules between the different environments. This enabled us to speedily adapt the code for the Electron-based desktop apps. However, we encountered some challenges.
|
||||
|
||||
### Overcoming challenges
|
||||
|
||||
While Electron allows us to integrate with the different platforms' desktop environments pretty easily, you can't underestimate the time investment to get things just right! In the end, it was these little things that took up much more time than we expected but were also crucial to finish the desktop client project.
|
||||
|
||||
The places where platform-specific code was necessary caused most of the friction:
|
||||
|
||||
* Window management and the tray, for example, are still handled in subtly different ways on the three platforms.
|
||||
* Registering Tutanota as the default mail program and setting up autostart required diving into the Windows Registry while making sure to prompt the user for admin access in a [UAC][12]-compatible way.
|
||||
* We needed to use Electron's API for shortcuts and menus to offer even standard features like copy, paste, undo, and redo.
|
||||
|
||||
|
||||
|
||||
This process was complicated a bit by users' expectations of certain, sometimes not directly compatible behavior of the apps on different platforms. Making the three versions feel native required some iteration and even some modest additions to the web app to offer a text search similar to the one in the browser.
|
||||
|
||||
### Wrapping up
|
||||
|
||||
Our experience with Electron was largely positive, and we completed the project in less than four months. Despite some rather time-consuming features, we were surprised about the ease with which we could ship a beta version of the [Tutanota desktop client for Linux][13]. If you're interested, you can dive into the source code on [GitHub][14].
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/19/4/linux-desktop-electron
|
||||
|
||||
作者：[Nils Ganther][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://opensource.com/users/nils-ganther
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/email_paper_envelope_document.png?itok=uPj_kouJ (document sending)
|
||||
[2]: https://tutanota.com/
|
||||
[3]: https://f-droid.org/en/packages/de.tutao.tutanota/
|
||||
[4]: https://electronjs.org/
|
||||
[5]: https://github.com/systemjs/systemjs
|
||||
[6]: https://mithril.js.org/
|
||||
[7]: https://tutanota.uservoice.com/forums/237921-general/filters/top?status_id=1177482
|
||||
[8]: https://tutanota.com/blog/posts/first-search-encrypted-data/
|
||||
[9]: https://electronjs.org/docs/tutorial/security
|
||||
[10]: https://www.blackhat.com/docs/us-17/thursday/us-17-Carettoni-Electronegativity-A-Study-Of-Electron-Security-wp.pdf
|
||||
[11]: https://babeljs.io/
|
||||
[12]: https://en.wikipedia.org/wiki/User_Account_Control
|
||||
[13]: https://tutanota.com/blog/posts/desktop-clients/
|
||||
[14]: https://www.github.com/tutao/tutanota
|
||||
135
sources/tech/20190411 Be your own certificate authority.md
Normal file
135
sources/tech/20190411 Be your own certificate authority.md
Normal file
@@ -0,0 +1,135 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (Be your own certificate authority)
|
||||
[#]: via: (https://opensource.com/article/19/4/certificate-authority)
|
||||
[#]: author: (Moshe Zadka (Community Moderator) https://opensource.com/users/moshez/users/elenajon123)
|
||||
|
||||
Be your own certificate authority
|
||||
======
|
||||
Create a simple, internal CA for your microservice architecture or
|
||||
integration testing.
|
||||
![][1]
|
||||
|
||||
The Transport Layer Security ([TLS][2]) model, which is sometimes referred to by the older name SSL, is based on the concept of [certificate authorities][3] (CAs). These authorities are trusted by browsers and operating systems and, in turn, _sign_ servers' certificates to validate their ownership.
|
||||
|
||||
However, for an intranet, a microservice architecture, or integration testing, it is sometimes useful to have a _local CA_ : one that is trusted only internally and, in turn, signs local servers' certificates.
|
||||
|
||||
This especially makes sense for integration tests. Getting certificates can be a burden because the servers will be up for minutes. But having an "ignore certificate" option in the code could allow it to be activated in production, leading to a security catastrophe.
|
||||
|
||||
A CA certificate is not much different from a regular server certificate; what matters is that it is trusted by local code. For example, in the **requests** library, this can be done by setting the **REQUESTS_CA_BUNDLE** variable to a directory containing this certificate.
|
||||
|
||||
In the example of creating a certificate for integration tests, there is no need for a _long-lived_ certificate: if your integration tests take more than a day, you have already failed.
|
||||
|
||||
So, calculate **yesterday** and **tomorrow** as the validity interval:
|
||||
|
||||
|
||||
```
|
||||
>>> import datetime
|
||||
>>> one_day = datetime.timedelta(days=1)
|
||||
>>> today = datetime.date.today()
|
||||
>>> yesterday = today - one_day
|
||||
>>> tomorrow = today - one_day
|
||||
```
|
||||
|
||||
Now you are ready to create a simple CA certificate. You need to generate a private key, create a public key, set up the "parameters" of the CA, and then self-sign the certificate: a CA certificate is _always_ self-signed. Finally, write out both the certificate file as well as the private key file.
|
||||
|
||||
|
||||
```
|
||||
from cryptography.hazmat.primitives.asymmetric import rsa
|
||||
from cryptography.hazmat.primitives import hashes, serialization
|
||||
from cryptography import x509
|
||||
from cryptography.x509.oid import NameOID
|
||||
|
||||
private_key = rsa.generate_private_key(
|
||||
public_exponent=65537,
|
||||
key_size=2048,
|
||||
backend=default_backend()
|
||||
)
|
||||
public_key = private_key.public_key()
|
||||
builder = x509.CertificateBuilder()
|
||||
builder = builder.subject_name(x509.Name([
|
||||
x509.NameAttribute(NameOID.COMMON_NAME, 'Simple Test CA'),
|
||||
]))
|
||||
builder = builder.issuer_name(x509.Name([
|
||||
x509.NameAttribute(NameOID.COMMON_NAME, 'Simple Test CA'),
|
||||
]))
|
||||
builder = builder.not_valid_before(yesterday)
|
||||
builder = builder.not_valid_after(tomorrow)
|
||||
builder = builder.serial_number(x509.random_serial_number())
|
||||
builder = builder.public_key(public_key)
|
||||
builder = builder.add_extension(
|
||||
x509.BasicConstraints(ca=True, path_length=None),
|
||||
critical=True)
|
||||
certificate = builder.sign(
|
||||
private_key=private_key, algorithm=hashes.SHA256(),
|
||||
backend=default_backend()
|
||||
)
|
||||
private_bytes = private_key.private_bytes(
|
||||
encoding=serialization.Encoding.PEM,
|
||||
format=serialization.PrivateFormat.TraditionalOpenSSL,
|
||||
encryption_algorithm=serialization.NoEncrption())
|
||||
public_bytes = certificate.public_bytes(
|
||||
encoding=serialization.Encoding.PEM)
|
||||
with open("ca.pem", "wb") as fout:
|
||||
fout.write(private_bytes + public_bytes)
|
||||
with open("ca.crt", "wb") as fout:
|
||||
fout.write(public_bytes)
|
||||
```
|
||||
|
||||
In general, a real CA will expect a [certificate signing request][4] (CSR) to sign a certificate. However, when you are your own CA, you can make your own rules! Just go ahead and sign what you want.
|
||||
|
||||
Continuing with the integration test example, you can create the private keys and sign the corresponding public keys right then. Notice **COMMON_NAME** needs to be the "server name" in the **https** URL. If you've configured name lookup, the needed server will respond on **service.test.local**.
|
||||
|
||||
|
||||
```
|
||||
service_private_key = rsa.generate_private_key(
|
||||
public_exponent=65537,
|
||||
key_size=2048,
|
||||
backend=default_backend()
|
||||
)
|
||||
service_public_key = service_private_key.public_key()
|
||||
builder = x509.CertificateBuilder()
|
||||
builder = builder.subject_name(x509.Name([
|
||||
x509.NameAttribute(NameOID.COMMON_NAME, 'service.test.local')
|
||||
]))
|
||||
builder = builder.not_valid_before(yesterday)
|
||||
builder = builder.not_valid_after(tomorrow)
|
||||
builder = builder.public_key(public_key)
|
||||
certificate = builder.sign(
|
||||
private_key=private_key, algorithm=hashes.SHA256(),
|
||||
backend=default_backend()
|
||||
)
|
||||
private_bytes = service_private_key.private_bytes(
|
||||
encoding=serialization.Encoding.PEM,
|
||||
format=serialization.PrivateFormat.TraditionalOpenSSL,
|
||||
encryption_algorithm=serialization.NoEncrption())
|
||||
public_bytes = certificate.public_bytes(
|
||||
encoding=serialization.Encoding.PEM)
|
||||
with open("service.pem", "wb") as fout:
|
||||
fout.write(private_bytes + public_bytes)
|
||||
```
|
||||
|
||||
Now the **service.pem** file has a private key and a certificate that is "valid": it has been signed by your local CA. The file is in a format that can be given to, say, Nginx, HAProxy, or most other HTTPS servers.
|
||||
|
||||
By applying this logic to testing scripts, it's easy to create servers that look like authentic HTTPS servers, as long as the client is configured to trust the right CA.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/19/4/certificate-authority
|
||||
|
||||
作者：[Moshe Zadka (Community Moderator)][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://opensource.com/users/moshez/users/elenajon123
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/rh_commun_4604_02_mech_connections_rhcz0.5x.png?itok=YPPU4dMj
|
||||
[2]: https://en.wikipedia.org/wiki/Transport_Layer_Security
|
||||
[3]: https://en.wikipedia.org/wiki/Certificate_authority
|
||||
[4]: https://en.wikipedia.org/wiki/Certificate_signing_request
|
||||
@@ -0,0 +1,73 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (How do you contribute to open source without code?)
|
||||
[#]: via: (https://opensource.com/article/19/4/contribute-without-code)
|
||||
[#]: author: (Chris Hermansen (Community Moderator) https://opensource.com/users/clhermansen/users/don-watkins/users/greg-p/users/petercheer)
|
||||
|
||||
How do you contribute to open source without code?
|
||||
======
|
||||
|
||||
![Dandelion held out over water][1]
|
||||
|
||||
My earliest open source contributions date back to the mid-1980s when our organization first connected to [UseNet][2] where we discovered the contributed code and the opportunities to share in its development and support.
|
||||
|
||||
Today there are endless contribution opportunities, from contributing code to making how-to videos.
|
||||
|
||||
I'm going to step right over the whole issue of contributing code, other than pointing out that many of us who write code but don't consider ourselves developers can still [contribute code][3]. Instead, I'd like to remind everyone that there are lots of [non-code ways to contribute to open source][4] and talk about three alternatives.
|
||||
|
||||
### Filing bug reports
|
||||
|
||||
One important and concrete kind of contribution could best be described as "not being afraid to file a decent bug report" and [all the consequences related to that][5]. Sometimes it's quite challenging to [file a decent bug report][6]. For example:
|
||||
|
||||
* A bug may be difficult to record or describe. A long and complicated message with all sorts of unrecognizable codes may flash by as the computer is booting, or there may just be some "odd behavior" on the screen with no error messages produced.
|
||||
* A bug may be difficult to reproduce. It may occur only on certain hardware/software configurations, or it may be rarely triggered, or the precise problem area may not be apparent.
|
||||
* A bug may be linked to a very specific development environment configuration that is too big, messy, and complicated to share, requiring laborious creation of a stripped-down example.
|
||||
* When reporting a bug to a distro, the maintainers may suggest filing the bug upstream instead, which can sometimes lead to a lot of work when the version supported by the distro is not the primary version of interest to the upstream community. (This can happen when the version provided in the distro lags the officially supported release and development version.)
|
||||
|
||||
|
||||
|
||||
Nevertheless, I exhort would-be bug reporters (including me) to press on and try to get bugs fully recorded and acknowledged.
|
||||
|
||||
One way to get started is to use your favorite search tool to look for similar bug reports, see how they are described, where they are filed, and so on. Another important thing to know is the formal mechanism defined for bug reporting by your distro (for example, [Fedora's is here][7]; [openSUSE's is here][8]; [Ubuntu's is here][9]) or software package ([LibreOffice's is here][10]; [Mozilla's seems to be here][11]).
|
||||
|
||||
### Answering user's questions
|
||||
|
||||
I lurk and occasionally participate in various mailing lists and forums, such as the [Ubuntu quality control team][12] and [forums][13], [LinuxQuestions.org][14], and the [ALSA users' mailing list][15]. Here, the contributions may relate less to bugs and more to documenting complex use cases. It's a great feeling for everyone to see someone jumping in to help a person sort out their trouble with a particular issue.
|
||||
|
||||
### Writing about open source
|
||||
|
||||
Finally, another area where I really enjoy contributing is [_writing_][16] about using open source software; whether it's a how-to guide, a comparative evaluation of different solutions to a particular problem, or just generally exploring an area of interest (in my case, using open source music-playing software to enjoy music). A similar option is making an instructional video; it's easy to [record the desktop][17] while demonstrating some fiendishly difficult desktop maneuver, such as creating a splashy logo with GIMP. And those of you who are bi- or multi-lingual can also consider translating existing how-to articles or videos to another language.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/19/4/contribute-without-code
|
||||
|
||||
作者：[Chris Hermansen (Community Moderator)][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://opensource.com/users/clhermansen/users/don-watkins/users/greg-p/users/petercheer
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/dandelion_blue_water_hand.jpg?itok=QggW8Wnw (Dandelion held out over water)
|
||||
[2]: https://en.wikipedia.org/wiki/Usenet
|
||||
[3]: https://opensource.com/article/19/2/open-science-git
|
||||
[4]: https://opensource.com/life/16/1/8-ways-contribute-open-source-without-writing-code
|
||||
[5]: https://producingoss.com/en/bug-tracker.html
|
||||
[6]: https://opensource.com/article/19/3/bug-reporting
|
||||
[7]: https://docs.fedoraproject.org/en-US/quick-docs/howto-file-a-bug/
|
||||
[8]: https://en.opensuse.org/openSUSE:Submitting_bug_reports
|
||||
[9]: https://help.ubuntu.com/stable/ubuntu-help/report-ubuntu-bug.html.en
|
||||
[10]: https://wiki.documentfoundation.org/QA/BugReport
|
||||
[11]: https://developer.mozilla.org/en-US/docs/Mozilla/QA/Bug_writing_guidelines
|
||||
[12]: https://wiki.ubuntu.com/QATeam
|
||||
[13]: https://ubuntuforums.org/
|
||||
[14]: https://www.linuxquestions.org/
|
||||
[15]: https://www.alsa-project.org/wiki/Mailing-lists
|
||||
[16]: https://opensource.com/users/clhermansen
|
||||
[17]: https://opensource.com/education/16/10/simplescreenrecorder-and-kazam
|
||||
@@ -0,0 +1,135 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (Installing Ubuntu MATE on a Raspberry Pi)
|
||||
[#]: via: (https://itsfoss.com/ubuntu-mate-raspberry-pi/)
|
||||
[#]: author: (Chinmay https://itsfoss.com/author/chinmay/)
|
||||
|
||||
Installing Ubuntu MATE on a Raspberry Pi
|
||||
======
|
||||
|
||||
_**Brief: This quick tutorial shows you how to install Ubuntu MATE on Raspberry Pi devices.**_
|
||||
|
||||
[Raspberry Pi][1] is by far the most popular SBC (Single Board Computer) and the go-to board for makers. [Raspbian][2] which is based on Debian is the official operating system for the Pi. It is lightweight, comes bundled with educational tools and gets the job done for most scenarios.
|
||||
|
||||
[Installing Raspbian][3] is easy as well but the problem with [Debian][4] is its slow upgrade cycles and older packages.
|
||||
|
||||
Running Ubuntu on the Raspberry Pi gives you a richer experience and up to date software. We have a few options when it comes to running Ubuntu on your Pi.
|
||||
|
||||
1. [Ubuntu MATE][5] : Ubuntu MATE is the only distribution which natively supports the Raspberry Pi with a complete desktop environment.
|
||||
2. [Ubuntu Server 18.04][6] \+ Installing a desktop environment manually.
|
||||
3. Using Images built by the [Ubuntu Pi Flavor Maker][7] community, _these images only support the Raspberry Pi 2B and 3B variants_ and are **not** updated to the latest LTS release.
|
||||
|
||||
|
||||
|
||||
The first option is the easiest and the quickest to set up while the second option gives you the freedom to install the desktop environment of your choice. I recommend going with either of the first two options.
|
||||
|
||||
Here are the links to download the Disc Images. In this article I’ll be covering Ubuntu MATE installation only.
|
||||
|
||||
### Installing Ubuntu MATE on Raspberry Pi
|
||||
|
||||
Go to the download page of Ubuntu MATE and get the recommended images.
|
||||
|
||||
![][8]
|
||||
|
||||
The experimental ARM64 version should only be used if you need to run 64-bit only applications like MongoDB on a Raspberry Pi server.
|
||||
|
||||
[Download Ubuntu MATE for Raspberry Pi][9]
|
||||
|
||||
#### Step 1: Setting Up the SD Card
|
||||
|
||||
The image file needs to be decompressed once downloaded. You can simply right click on it to extract it.
|
||||
|
||||
Alternatively, the following command will do the job.
|
||||
|
||||
```
|
||||
xz -d ubuntu-mate***.img.xz
|
||||
```
|
||||
|
||||
Alternatively you can use [7-zip][10] if you are on Windows.
|
||||
|
||||
Install **[Balena Etcher][11]** , we’ll use this tool to write the image to the SD card. Make sure that your SD card is at least 8 GB capacity.
|
||||
|
||||
Launch Etcher and select the image file and your SD card.
|
||||
|
||||
![][12]
|
||||
|
||||
Once the flashing process is complete the SD card is ready.
|
||||
|
||||
#### Step 2: Setting Up the Raspberry Pi
|
||||
|
||||
You probably already know that you need a few things to get started with Raspberry Pi such as a mouse, keyboard, HDMI cable etc. You can also [install Raspberry Pi headlessly without keyboard and mouse][13] but this tutorial is not about that.
|
||||
|
||||
* Plug in a mouse and a keyboard.
|
||||
* Connect the HDMI cable.
|
||||
* Insert the SD card into the SD card slot.
|
||||
|
||||
|
||||
|
||||
Power it on by plugging in the power cable. Make sure you have a good power supply (5V, 3A minimum). A bad power supply can reduce the performance.
|
||||
|
||||
#### Ubuntu MATE installation
|
||||
|
||||
Once you power on the Raspberry Pi, you’ll be greeted with a very familiar Ubuntu installation process. The process is pretty much straight forward from here.
|
||||
|
||||
![Select your keyboard layout][14]
|
||||
|
||||
![Select Your Timezone][15]
|
||||
|
||||
Select your WiFi network and enter the password in the network connection screen.
|
||||
|
||||
![Add Username and Password][16]
|
||||
|
||||
After setting the keyboard layout, timezone and user credentials you’ll be taken to the login screen after a few minutes. And voila! you are almost done.
|
||||
|
||||
![][17]
|
||||
|
||||
Once logged in, the first thing you should do is to [update Ubuntu][18]. You can use the command line for that.
|
||||
|
||||
```
|
||||
sudo apt update
|
||||
sudo apt upgrade
|
||||
```
|
||||
|
||||
You can also use the Software Updater.
|
||||
|
||||
![][19]
|
||||
|
||||
Once the updates are finished installing you are good to go. You can also go ahead and install Raspberry Pi specific packages for GPIO and other I/O depending on your needs.
|
||||
|
||||
What made you think about installing Ubuntu on the Raspberry and how has your experience been with Raspbian? Let me know in the comments below.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://itsfoss.com/ubuntu-mate-raspberry-pi/
|
||||
|
||||
作者：[Chinmay][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://itsfoss.com/author/chinmay/
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://www.raspberrypi.org/
|
||||
[2]: https://www.raspberrypi.org/downloads/
|
||||
[3]: https://itsfoss.com/tutorial-how-to-install-raspberry-pi-os-raspbian-wheezy/
|
||||
[4]: https://www.debian.org/
|
||||
[5]: https://ubuntu-mate.org/
|
||||
[6]: https://wiki.ubuntu.com/ARM/RaspberryPi#Recovering_a_system_using_the_generic_kernel
|
||||
[7]: https://ubuntu-pi-flavour-maker.org/download/
|
||||
[8]: https://i0.wp.com/itsfoss.com/wp-content/uploads/2019/04/ubuntu-mate-raspberry-pi-download.jpg?ssl=1
|
||||
[9]: https://ubuntu-mate.org/download/
|
||||
[10]: https://www.7-zip.org/download.html
|
||||
[11]: https://www.balena.io/etcher/
|
||||
[12]: https://i0.wp.com/itsfoss.com/wp-content/uploads/2019/04/Screenshot-from-2019-04-08-01-36-16.png?ssl=1
|
||||
[13]: https://linuxhandbook.com/raspberry-pi-headless-setup/
|
||||
[14]: https://i2.wp.com/itsfoss.com/wp-content/uploads/2019/04/Keyboard-layout-ubuntu.jpg?fit=800%2C467&ssl=1
|
||||
[15]: https://i2.wp.com/itsfoss.com/wp-content/uploads/2019/04/select-time-zone-ubuntu.jpg?fit=800%2C468&ssl=1
|
||||
[16]: https://i2.wp.com/itsfoss.com/wp-content/uploads/2019/04/Credentials-ubuntu.jpg?fit=800%2C469&ssl=1
|
||||
[17]: https://i2.wp.com/itsfoss.com/wp-content/uploads/2019/04/Desktop-ubuntu.jpg?fit=800%2C600&ssl=1
|
||||
[18]: https://itsfoss.com/update-ubuntu/
|
||||
[19]: https://i1.wp.com/itsfoss.com/wp-content/uploads/2019/04/update-software.png?ssl=1
|
||||
@@ -0,0 +1,103 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (Managed, enabled, empowered: 3 dimensions of leadership in an open organization)
|
||||
[#]: via: (https://opensource.com/open-organization/19/4/managed-enabled-empowered)
|
||||
[#]: author: (Heidi Hess von Ludewig (Red Hat) https://opensource.com/users/heidi-hess-von-ludewig/users/amatlack)
|
||||
|
||||
Managed, enabled, empowered: 3 dimensions of leadership in an open organization
|
||||
======
|
||||
Different types of work call for different types of engagement. Should
|
||||
open leaders always aim for empowerment?
|
||||
![][1]
|
||||
|
||||
"Empowerment" seems to be the latest people management [buzzword][2]. And it's an important consideration for open organizations, too. After all, we like to think these open organizations thrive when the people inside them are equipped to take initiative to do their best work as they see fit. Shouldn't an open leader's goal be complete and total empowerment of everyone, in all parts of the organization, doing all types of work?
|
||||
|
||||
Not necessarily.
|
||||
|
||||
Before we jump on the employee [empowerment bandwagon][3], we should explore the important connections between empowerment and innovation. That requires placing empowerment in context.
|
||||
|
||||
As Allison Matlack has already demonstrated, employee investment in an organization's mission and activities—and employee _autonomy_ relative to those things—[can take several forms][4], from "managed" to "enabled" to "empowered." Sometimes, complete and total empowerment _isn't_ the most desirable type of investment an open leader would like to activate in a contributor. Projects are always changing. New challenges are always arising. As a result, the _type_ or _degree_ of involvement leaders can expect in different situations is always shifting. "Managed," "enabled," and "empowered," contributors exist simultaneously and dynamically, depending on the work they're performing (and that work's desired outcomes).
|
||||
|
||||
So before we head down to the community center to win a game of buzzword bingo, let's examine the different types of work, how they function, and how they contribute to the overall innovation of a company. Let's refine what we mean by "managed," "enabled," and "empowered" work, and discuss why we need all three.
|
||||
|
||||
### Managed, enabled, empowered
|
||||
|
||||
First, let's consider and define each type of work activity.
|
||||
|
||||
"Managed" work involves tasks that are coordinated using guidance, supervision, and direction in order to achieve specific outcomes. When someone works to coordinate _every_ part of _every_ task, we colloquially call that behavior "micro-managing." "Enabled" associates have the ability to direct themselves while working within boundaries (guidance), and they have access to the materials and resources (information, people, technologies, etc.) they require to problem-solve as they see fit. Lastly, "empowered" individuals _direct themselves_ within organizational limits, have access materials and resources, and also have the authority to represent their team or organization and make decisions about work on behalf using their best judgement, based on the former elements.
|
||||
|
||||
Most important here is the idea that these concepts are _nested_ (see Figure 1). Because each level builds on the one before it, one cannot have the full benefit of "empowered" associates without also having clear guidance and direction ("managed"), and transparency of information and resources ("enabled"). What changes from level to level is the amount of managed or enabled activity that comes before it.
|
||||
|
||||
Let's dive more deeply into the nature of those activities and discuss the roles leaders should play in each.
|
||||
|
||||
#### Managed work
|
||||
|
||||
"Managed" work is just that: work activity supervised and directed to some degree. The amount of management occurring in a situation is dynamic and depends on the activity itself. For instance, in the manufacturing economy, managed work is prominent. I'll call this "widget" work, the point of which is producing a widget the same way, every time. People need to perform this work according to consistent processes with consistent, standardized outcomes.
|
||||
|
||||
Before we jump on the employee empowerment bandwagon, we should explore the important connections between empowerment and innovation. That requires placing empowerment in context.
|
||||
|
||||
Because this work requires consistency, it typically proceeds via explicit guidelines and policies (rules about cost, schedule, quality, quantity, process, and so on—characteristics applicable to all work to a greater or lesser degree). We can find examples of it in a variety of roles across many industries. Quite often, _any_ role in _any_ industry requires _some_ amount of this type of work. Examples include manufacturing precision machine parts, answering a customer support case within a specified timeframe for contractual reasons and with a friendly greeting, etc. In the software industry, a role that's _entirely_ like this would be a rarity, yet even these roles require some work of the "managed" type. For instance, consider the way a support engineer must respond to a case using a set of quality standards (friendliness, perhaps with a professional written tone, a branded signature line, adherence to a participat contractual agreement, usually responding within a particular time frame, etc.).
|
||||
|
||||
"Management" is the best strategy when _work requirements include adhering to a consistent schedule, process, and quality._
|
||||
|
||||
#### Enabled work
|
||||
|
||||
As the amount of creativity a role requires _increases_ , the amount of directed and "managed" work we find in that role _decreases_. Guidelines get broader, processes looser, schedules lengthened (I wish!). This is because what's required to "be creative" involves other types of work (and new degrees of transparency and authority along with them). Ron McFarland explains this in [his article on adaptive leadership][5]: Many challenges challenges are ambiguous, as opposed to technical, and therefore require specific kinds of leadership.
|
||||
|
||||
To take this idea one step further, we might say open leaders need to be _adaptive_ to how they view and implement the different kinds of work on their teams or in their organizations. "Enabling" associates means growing their skills and knowledge so they can manage themselves. The foundation for this type of activity is information—access to it, sharing it, and opportunities to independently use it to complete work activity. This is the kind of work Peter Drucker was referring to when he coined the term "knowledge work."
|
||||
|
||||
Enabled work liberates associates from the constraints of managed work, though it still involves leaders providing considerable direction and guidance. Outcomes of this work might be familiar and normalized, but the _paths to achieving them_ are more open-ended than in managed work. Methods are more flexible and inclusive of individual preference and capability.
|
||||
|
||||
"Enablement" is the best strategy when _objectives are well-defined and the outcomes are aligned with past outcomes and results_.
|
||||
|
||||
#### Empowered work
|
||||
|
||||
In "[Beyond Engagement][4]," Allison describes empowerment as a state in which employees have "access to all the information, training, tools, and connections to people and others teams that they need to do their best work, as well as a safe environment in which to do that work so they feel comfortable making their own decisions." In other words, empowerment is enablement with the opportunity for associates to _act using their own best judgment as it relates to shared understanding of team and organizational guidelines and objectives._
|
||||
|
||||
"Empowerment" is the best strategy when _objectives and methods for achieving them are unclear and creative flexibility is necessary for defining them._ Often this work is focused on activities where problem definition and possible solutions (i.e. investigation, planning, and execution) are not well-defined.
|
||||
|
||||
Any role in any organization involves these three types of work occurring at various moments and in various situations. No job requires just one.
|
||||
|
||||
### Supporting innovation through managed, enabled, and empowered work
|
||||
|
||||
The labels "managed," enabled," and "empowered" apply to different work at different times, and _all three_ are embedded in work activity at different times and in different tasks. That means leaders should be paying more attention to the work contributors are doing: the kind of work, its purpose, and its desired outcomes. We're now in a position to consider how _innovation_ factors into this equation.
|
||||
|
||||
Frequently, people discuss the different modes of work by way of _contrast_. Most language about them connotes negativity: managed work is "the worst," while empowered work is "the best." The goal of any leadership practice should be to "move people along the scale"—to create empowered contributors.
|
||||
|
||||
However, just as types of work are located on a continuum that doesn't include this element of negation, so too should our understanding of the types of work. Rather than seeing work as, for example " _always empowered"_ or _"always managed_ ," we should recognize that any role is a function of _of all three types of work at the same time_ , each to a varying degree. Think of the equation this way:
|
||||
|
||||
> _Work = managed (x) + enabled (x) + empowered (x)_
|
||||
|
||||
Note here that the more enabled and empowered the work is, the more potential there is for creativity when doing that work. This is because creativity (and the creative individual) requires information—consistently updated and "fresh" sources of information—used in conjunction with individual judgment and capacity for interpreting how to _use_ and _combine_ that information to define problems, ideate, and solve problems. Enabled and empowered work can increase inclusivity—that is, draw more closely on an individual's unique skills, perspectives, and talents because, by definition, those kinds of work are less managed and more guided. Open leadership clearly supports hiring for diversity exactly for the reason that it makes inclusivity so much richer. The ambiguity that's characteristic of the challenges we face in modern workplaces means that the work we do is ripe with potential for innovation—if we embrace risk and adapt our leadership styles to liberate it.
|
||||
|
||||
In other words:
|
||||
|
||||
> _Innovation = enabled (x) + empowered (x) / managed (x)_
|
||||
>
|
||||
> _The more enabled and empowered the work is, the more potential for innovation._
|
||||
|
||||
Focusing on the importance of enabled work and empowered work is not to devalue managed work in any way. I would say that managed work creates a stable foundation on which creative (enabled and empowered) work can blossom. Imagine if all the work we did was empowered; our organizations would be completely chaotic, undefined, and ambiguous. Organizations need a degree of managed work in order to ensure some direction, some understanding of priorities, and some definition of "quality."
|
||||
|
||||
Any role in any organization involves these three types of work occurring at various moments and in various situations. No job requires just one. As open leaders, we must recognize that work isn't an all-or-nothing, one-type-of-work-alone equation. We have to get better at understanding work in _these three different ways_ and using each one to the organization's advantage, depending on the situation.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/open-organization/19/4/managed-enabled-empowered
|
||||
|
||||
作者：[Heidi Hess von Ludewig (Red Hat)][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://opensource.com/users/heidi-hess-von-ludewig/users/amatlack
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/BIZ_ControlNotDesirable.png?itok=nrXwSkv7
|
||||
[2]: https://www.entrepreneur.com/article/288340
|
||||
[3]: https://www.forbes.com/sites/lisaquast/2011/02/28/6-ways-to-empower-others-to-succeed/#5c860b365c62
|
||||
[4]: https://opensource.com/open-organization/18/10/understanding-engagement-and-empowerment
|
||||
[5]: https://opensource.com/open-organization/19/3/adaptive-leadership-review
|
||||
@@ -0,0 +1,57 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (Testing Small Scale Scrum in the real world)
|
||||
[#]: via: (https://opensource.com/article/19/4/next-steps-small-scale-scrum)
|
||||
[#]: author: (Agnieszka Gancarczyk (Red Hat)Leigh Griffin (Red Hat) https://opensource.com/users/agagancarczyk/users/lgriffin/users/agagancarczyk/users/lgriffin)
|
||||
|
||||
Testing Small Scale Scrum in the real world
|
||||
======
|
||||
We plan to test the Small Scale Scrum framework in real-world projects
|
||||
involving small teams.
|
||||
![Green graph of measurements][1]
|
||||
|
||||
Scrum is built on the three pillars of inspection, adaptation, and transparency. Our empirical research is really the starting point in bringing scrum, one of the most popular agile implementations, to smaller teams. As presented in the diagram below, we are now taking time to inspect this framework and principles by testing them in real-world projects.
|
||||
|
||||
![small-scale-scrum-inspection.png][2]
|
||||
|
||||
Progress in empirical process control
|
||||
|
||||
We plan to implement Small Scale Scrum in several upcoming projects. Our test candidates are customers with real projects where teams of one to three people will undertake short-lived projects (ranging from a few weeks to three months) with an emphasis on quality and outputs. Individual projects, such as final-year projects (over 24 weeks) that are a capstone project after four years in a degree program, are almost exclusively completed by a single person. In projects of this nature, there is an emphasis on the project plan and structure and on maximizing the outputs that a single person can achieve.
|
||||
|
||||
We plan to metricize and publish the results of these projects and hold several retrospectives with the teams involved. We are particularly interested in metrics centered around quality, with a particular emphasis on quality in a software engineering context and management, both project management through the lifecycle with a customer and management of the day-to-day team activities and the delivery, release, handover, and signoff process.
|
||||
|
||||
Ultimately, we will retrospectively analyze the overall framework and principles and see if the Manifesto we envisioned holds up to the reality of executing a project with small numbers. From this data, we will produce the second version of Small Scale Scrum and begin a cyclic pattern of inspecting the model in new projects and adapting it again.
|
||||
|
||||
We want to do all of this transparently. This series of articles is one window into the data, the insights, the experiences, and the reality of running scrum for small teams whose everyday challenges include context switching, communication, and the need for a quality delivery. A follow-up series of articles is planned to examine the outputs and help develop the second edition of Small Scale Scrum entirely in the community.
|
||||
|
||||
We also plan to attend conferences and share our knowledge with the Agile community. Our first conference will be Agile 2019 where the evolution of Small Scale Scrum will be further explored as an Experience Report. We are advising colleges and sharing our structure and approach to managing and executing final-year projects. All our outputs will be freely available in the open source way.
|
||||
|
||||
Given the changes to recommended team sizes in the Scrum Guide, our long-term goal and vision is to have the Scrum Guide reflect that teams of one or more people occupying one or more roles within a project are capable of following scrum.
|
||||
|
||||
* * *
|
||||
|
||||
_Leigh Griffin will present Small Scale Scrum at Agile 2019 in Washington, August 5-9, 2019 as an Experience Report. An expanded paper will be published on[Agile Alliance][3] to accompany this._
|
||||
|
||||
* * *
|
||||
|
||||
* * *
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/19/4/next-steps-small-scale-scrum
|
||||
|
||||
作者：[Agnieszka Gancarczyk (Red Hat)Leigh Griffin (Red Hat)][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://opensource.com/users/agagancarczyk/users/lgriffin/users/agagancarczyk/users/lgriffin
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/metrics_lead-steps-measure.png?itok=DG7rFZPk (Green graph of measurements)
|
||||
[2]: https://opensource.com/sites/default/files/small-scale-scrum-inspection.png (small-scale-scrum-inspection.png)
|
||||
[3]: https://www.agilealliance.org/
|
||||
@@ -0,0 +1,131 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (Designing posters with Krita, Scribus, and Inkscape)
|
||||
[#]: via: (https://opensource.com/article/19/4/design-posters)
|
||||
[#]: author: (Raghavendra Kamath https://opensource.com/users/raghukamath/users/seilarashel/users/raghukamath/users/raghukamath/users/greg-p/users/raghukamath)
|
||||
|
||||
Designing posters with Krita, Scribus, and Inkscape
|
||||
======
|
||||
Graphic designers can do professional work with free and open source
|
||||
tools.
|
||||
![Hand drawing out the word "code"][1]
|
||||
|
||||
A few months ago, I was asked to design some posters for a local [Free Software Foundation][2] (FSF) event. Richard M. Stallman was [visiting][3] our country, and my friend [Abhas Abhinav][4] wanted to put up some posters and banners to promote his visit. I designed two posters for RMS's talk in Bangalore.
|
||||
|
||||
I create my artwork with F/LOSS (free/libre open source software) tools. Although many artists successfully use free software to create artwork, I repeatedly encounter comments in discussion forums claiming that free software is not made for creative work. This article is my effort to detail the process I typically use to create my artwork and to spread awareness that one can do professional work with the help of F/LOSS tools.
|
||||
|
||||
### Sketching some concepts
|
||||
|
||||
After understanding Abhas' initial requirements, I sat down to visualize some concepts. I am not that great of a copywriter, so I started reading the FSF website to get some copy material. I needed to finish the project in two days time, while simultaneously working on other projects. I started sketching some rough layouts. From five layouts, I liked three. I scanned them using [Skanlite][5]; although these sketches were very rough and would need proper layout and design, they were a good base for me to work from.
|
||||
|
||||
![Skanlite][6]
|
||||
|
||||
![Poster sketches][7]
|
||||
|
||||
![Poster sketch][8]
|
||||
|
||||
I had three concepts:
|
||||
|
||||
* On the [FSF's website][2], I read about taking free software to new frontiers, which made me think about the idea of "conquering a summit." Free software work is also filled with adventures, in my opinion, and sometimes a task may seem like scaling a summit. So, I thought showing some mountaineers would resonate well.
|
||||
* I also wanted to ask people to donate to FSF, so I sketched a hand giving a heart. I didn't feel any excitement in executing this idea, nevertheless, I kept it for backup in case I fell short of time.
|
||||
* The FSF website has a hashtag for a donation program called #thankGNU, so I thought about using this as the basis of my design. Repurposing my hand visual, I replaced the heart with a bouquet of flowers that has a heart-shaped card saying #thankGNU!
|
||||
|
||||
|
||||
|
||||
I know these are somewhat quick and safe concepts, but given the little time I had for the project, I went ahead with them.
|
||||
|
||||
My design process mostly depends on the kind of look I need in the final image. I choose my software and process according to my needs. I may use one software from start to finish or combine various software packages to accomplish what I need. For this project, I used [Krita][9] and [Scribus][10], with some minimal use of [Inkscape][11].
|
||||
|
||||
### Krita: Making the illustrations
|
||||
|
||||
I imported my sketches into [Krita][12] and started adding more defined lines and shapes.
|
||||
|
||||
For the first image, which has some mountaineers climbing, I used [vector layers][13] in Krita to add basic shapes and then used [Alpha Inheritance][14], which is similar to what is called Clipping Masks in Photoshop, to add texture and gradients inside the shapes. This helped me change the underlying base shape (in this case, the shape of the mountain in the first poster) anytime during the process. Krita also has a nice feature called the Reference Image tool, which lets you pin some references around your canvas (this helps a lot and saves many Alt+Tabs). Once I got the mountain how I wanted, according to the layout, I started painting the mountaineers and added more details for the ice and other features. I like grungy brushes and brushes that have a texture akin to chalks and sponges. Krita has a wide range of brushes as well as a brush engine, which makes replicating a traditional medium easier. After about 3.5 hours of painting, this image was ready for further processing.
|
||||
|
||||
I wanted the second poster to have the feel of an old-style book illustration. So, I created the illustration with inked lines, somewhat similar to what we see in textbooks or novels. Inking in Krita is really a time saver; since it has stabilizer options, your wavy, hand-drawn lines will be smooth and crisp. I added a textured background and some minimal colors beneath the lines. It took me about three hours to do this illustration as well.
|
||||
|
||||
![Poster][15]
|
||||
|
||||
![Poster][16]
|
||||
|
||||
### Scribus: Adding layout and typography
|
||||
|
||||
Once my illustrations were ready, it was time to move on to the next part: adding text and other things to the layout. For this, I used Scribus. Both Scribus and Krita have CMYK support. In both applications, you can soft-proof your artwork and make changes according to the color profile you get from the printer. I mostly do my work in RGB and then, if required, I convert it to CMYK. Since most printers nowadays will do the color conversion, I don't think CMYK is support required, however, it's good to be able to work in CMYK with free software tools.
|
||||
|
||||
I use open source fonts for my design work unless a client has licensed a closed font for use. A good way to browse for suitable fonts is [Google Fonts repository][17]. (I have the entire repository cloned.) Occasionally, I also browse fonts on [Font Library][18], as it also has a nice collection. I decided to use Montserrat by Julieta Ulanovsky for the posters. Placing text was very quick in Scribus; once you create a style, you can apply it to any number of paragraphs or titles. This helped me place text in both designs quickly since I didn't have to re-create the text properties.
|
||||
|
||||
![Poster in Scribus][19]
|
||||
|
||||
I keep two layers in Scribus. One is for the illustrations, which are linked to the original files so if I change an illustration, it will update in Scribus. The other is for text and it's layered on top of the illustration layer.
|
||||
|
||||
### Inkscape: QR codes
|
||||
|
||||
I used Inkscape to generate a QR code that points to the Membership page on FSF's website. To generate a QR code in Scribus, go to **Extensions > Render > Barcode > QR Code** in Inkscape's menu. The logos are also vector; because Scribus supports vector images, you can directly paste things from Inkscape into Scribus. In a way, this helps in designing CMYK-based vector graphics.
|
||||
|
||||
![Final poster design][20]
|
||||
|
||||
![Final poster design][21]
|
||||
|
||||
With the designs ready, I exported them to layered PDF and sent to them to Abhas for feedback. He asked me to add FSF India's logo, which I did and sent a new PDF to him.
|
||||
|
||||
### Printing the posters
|
||||
|
||||
From here, Abhas took over the printing part of the process. His local printer in Bangalore printed the posters in A2 size. He was kind enough to send me some pictures of them. The prints came out well, considering I didn't even convert them to CMYK nor do any color corrections or soft proofing, as I usually do when I get the color profile from my printer. My opinion is that 100% accurate CMYK printing is just a myth; there are too many factors to consider. If I really want perfect color reproduction, I leave this job to the printer, as they know their printer well and can do the conversion.
|
||||
|
||||
![Final poster design][22]
|
||||
|
||||
![Final poster design][23]
|
||||
|
||||
### Accessing the source files
|
||||
|
||||
When we discussed the requirements for these posters, Abhas told me to release the artwork under a Creative Commons license so others can re-use, modify, and share it. I am really glad he mentioned it. Anyone who wants to poke at the files can [download them from my Nextcloud drive][24]. If you have any improvements to make, please go ahead—and do remember to share your work with everybody.
|
||||
|
||||
Let me know what you think about this article by [emailing me][25].
|
||||
|
||||
* * *
|
||||
|
||||
_[This article][26] originally appeared on [Raghukamath.com][27] and is republished with the author's permission._
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/19/4/design-posters
|
||||
|
||||
作者：[Raghavendra Kamath][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://opensource.com/users/raghukamath/users/seilarashel/users/raghukamath/users/raghukamath/users/greg-p/users/raghukamath
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/code_hand_draw.png?itok=dpAf--Db (Hand drawing out the word "code")
|
||||
[2]: https://www.fsf.org/
|
||||
[3]: https://rms-tour.gnu.org.in/
|
||||
[4]: https://abhas.io/
|
||||
[5]: https://kde.org/applications/graphics/skanlite/
|
||||
[6]: https://opensource.com/sites/default/files/uploads/skanlite.png (Skanlite)
|
||||
[7]: https://opensource.com/sites/default/files/uploads/sketch-01.png (Poster sketches)
|
||||
[8]: https://opensource.com/sites/default/files/uploads/sketch-02.png (Poster sketch)
|
||||
[9]: https://krita.org/
|
||||
[10]: https://www.scribus.net/
|
||||
[11]: https://inkscape.org/
|
||||
[12]: /life/16/4/nick-hamilton-linuxfest-northwest-2016-krita
|
||||
[13]: https://docs.krita.org/en/user_manual/vector_graphics.html#vector-graphics
|
||||
[14]: https://docs.krita.org/en/tutorials/clipping_masks_and_alpha_inheritance.html
|
||||
[15]: https://opensource.com/sites/default/files/uploads/poster-illo-01.jpg (Poster)
|
||||
[16]: https://opensource.com/sites/default/files/uploads/poster-illo-02.jpg (Poster)
|
||||
[17]: https://fonts.google.com/
|
||||
[18]: https://fontlibrary.org/
|
||||
[19]: https://opensource.com/sites/default/files/uploads/poster-in-scribus.png (Poster in Scribus)
|
||||
[20]: https://opensource.com/sites/default/files/uploads/final-01.png (Final poster design)
|
||||
[21]: https://opensource.com/sites/default/files/uploads/final-02.png (Final poster design)
|
||||
[22]: https://opensource.com/sites/default/files/uploads/posters-in-action-01.jpg (Final poster design)
|
||||
[23]: https://opensource.com/sites/default/files/uploads/posters-in-action-02.jpg (Final poster design)
|
||||
[24]: https://box.raghukamath.com/cloud/index.php/s/97KPnTBP4QL4iCx
|
||||
[25]: mailto:raghu@raghukamath.com?Subject=designing-posters-with-free-software
|
||||
[26]: https://raghukamath.com/journal/designing-posters-with-free-software/
|
||||
[27]: https://raghukamath.com/
|
||||
@@ -0,0 +1,71 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (How libraries are adopting open source)
|
||||
[#]: via: (https://opensource.com/article/19/4/software-libraries)
|
||||
[#]: author: (Don Watkins (Community Moderator) https://opensource.com/users/don-watkins)
|
||||
|
||||
How libraries are adopting open source
|
||||
======
|
||||
Over the past decade, ByWater Solutions has expanded its business by
|
||||
advocating for open source software.
|
||||
![][1]
|
||||
|
||||
Four years ago, I [interviewed Nathan Currulla][2], co-founder of ByWater Solutions, a major services and solutions provider for [Koha][3], a popular open source integrated library system (ILS). Since then, I've benefitted directly from his company's work, as my local [Chautauqua–Cattaraugus Library System][4] in western New York migrated from a proprietary software system to a [ByWater Systems][5]' Koha implementation.
|
||||
|
||||
When I learned that ByWater is celebrating its 10th anniversary in 2019, I decided to reach out to Nathan to learn how the company has grown over the last decade. (Our remarks have been edited slightly for grammar and clarity.)
|
||||
|
||||
**Don Watkins** : How has ByWater grown in the last 10 years?
|
||||
|
||||
**Nathan Currulla** : Over the last 10 years, ByWater has grown by leaps and bounds. By the end of 2009, we supported five libraries with five contracts. That number shot up to 117 libraries made up of 46 contracts by the end of 2010. We now support over 1,500 libraries and 450+ contracts. We also went from having two team members to 25 in the past 10 years. The service-focused processes we have developed for migrating new libraries have been adopted by other library companies, and we have become a real market disruptor, putting pressure on other companies to provide better support and lower software subscription fees for libraries using their products. This was our goal from the outset, to change the way libraries work with the technology companies who support them, whomever they may be.
|
||||
|
||||
Since the beginning, we have been rooted in the future, while legacy systems are still rooted in the past. Ten years ago, it was a real struggle for us to overcome the barriers presented by the fear of change in libraries and the outdated perceptions of open source in general. Now, although we still have to deal with change aversion, there are enough users to disprove any misinformation that exists regarding Koha and open source. The conversation is easier now than it ever was. That said, despite the fact that the ideals and morals held by open source are directly aligned with those of libraries, we still have a long way to go until open source technologies are the norm in this marketplace.
|
||||
|
||||
**DW** : What kinds of libraries do you support?
|
||||
|
||||
**NC** : Our partners are made up of a diverse set of library types. About 35% of our partners are public libraries, 35% are academic, and the remaining 30% are made up of museum, corporate, law, school, and other special library types. Because of Koha's flexibility and diverse feature set, we can successfully provide services to a variety of library types despite the current trend of consolidation in the library technology marketplace.
|
||||
|
||||
**DW** : How does ByWater work with and help the Koha community?
|
||||
|
||||
**NC** : We are working with the rest of the Koha community to streamline workflows and further improve the process of submitting and accepting new features into Koha. The vast majority of the community is made up of volunteers; by providing paid positions within the community, we can dedicate more time to the quality assurance and sign-off processes needed to stay competitive with other systems, both open source and proprietary. The number of new features submitted to the Koha community for each release is staggering. The more resources we have to get those features out to our users, the faster Koha can evolve and further shape the library-technology marketplace.
|
||||
|
||||
**DW** : When we talked in 2015, ByWater had recently partnered with library solutions provider [EBSCO][6]. What initiatives are you working on now with EBSCO?
|
||||
|
||||
**NC** : Originally, Catalyst IT of New Zealand worked with EBSCO to create the EBSCO Discovery Service (EDS) plugin that is used by many of our customers. Unlike most discovery systems that sit on top of a library's online public access catalog (OPAC), Koha's integration with EDS uses the Koha OPAC as the frontend, with EDS feeding data into the Koha interface. This allows libraries to choose which interface they prefer (EDS or Koha as the frontend) and provides a unified library service platform (LSP). EBSCO has always been a great partner and has always shown a strong willingness to contribute to the open source initiative. They understand the importance of having fewer barriers between the ILS and the libraries' other content to provide a seamless interface to the end user.
|
||||
|
||||
Outside of Koha, ByWater is working closely with EBSCO to provide implementation, training, and support services for its [Folio LSP][7]. Folio is an open source LSP for academic libraries with the intent to provide even more seamless integration with other content providers using an extensible, open app marketplace. ByWater is developing a separate department for the implementation and ongoing support of Folio, with EBSCO providing hosting services to our mutual customers. The fact that EBSCO is investing millions in the creation of an open source platform lends further credence to the importance and validity of open source technologies in the library market.
|
||||
|
||||
**DW** : What other projects are you supporting? How do they complement Koha?
|
||||
|
||||
**NC** : ByWater also supports Libki, an open source, web-based kiosk and print management solution; Coral, an open source electronic resource management (ERM) solution; and Folio. Libki and Coral seamlessly integrate with Koha to provide a unified LSP. Folio may work in cooperation with Koha on some functionality, but it is too early to tell what that will specifically look like.
|
||||
|
||||
ByWater also offers Koha Klassmates, a program that provides free installations of Koha to over 40 library schools in the US to familiarize the next generation of librarians with open source and the tools they will use daily in the workforce. We are also rolling out a program called Koha University, which will mentor computer science students in writing and submitting code to Koha, one of the largest open source projects in the world. This will give them experience in working in such an environment and provide the opportunity for their names to be listed as official Koha contributors.
|
||||
|
||||
**DW** : What is ByWater's strategic focus over the next five years?
|
||||
|
||||
**NC** : ByWater will continue offering top-rated support to our ever-growing customer base while leveraging new open source opportunities to disprove misinformation surrounding the use of open source solutions in libraries. We will focus on making open source the norm and educating libraries that could be taking advantage of these technologies but do not because of outdated information and perceptions.
|
||||
|
||||
Additionally, our research and development efforts will be focused on analyzing machine learning for advanced education and support services. We also want to work closely with our partners on advancing the marketing efforts (through software) for small and large libraries to help cement their roles as community centers by marketing inventory, programs, and library events. We want to be community builders on different levels, both for our partner libraries and with the open source communities that we are involved in.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/19/4/software-libraries
|
||||
|
||||
作者：[Don Watkins (Community Moderator)][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://opensource.com/users/don-watkins
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/EDUCATION_opencardcatalog.png?itok=f9PyJEe-
|
||||
[2]: https://opensource.com/business/15/5/bywater-solutions-empowering-library-tech
|
||||
[3]: http://www.koha.org/
|
||||
[4]: https://catalog.cclsny.org/
|
||||
[5]: https://bywatersolutions.com/
|
||||
[6]: https://www.ebsco.com/
|
||||
[7]: https://www.ebsco.com/products/ebsco-folio-library-services
|
||||
122
sources/tech/20190412 Joe Doss- How Do You Fedora.md
Normal file
122
sources/tech/20190412 Joe Doss- How Do You Fedora.md
Normal file
@@ -0,0 +1,122 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (Joe Doss: How Do You Fedora?)
|
||||
[#]: via: (https://fedoramagazine.org/joe-doss-how-do-you-fedora/)
|
||||
[#]: author: (Charles Profitt https://fedoramagazine.org/author/cprofitt/)
|
||||
|
||||
Joe Doss: How Do You Fedora?
|
||||
======
|
||||
|
||||
![Joe Doss][1]
|
||||
|
||||
We recently interviewed Joe Doss on how he uses Fedora. This is part of a [series][2] on the Fedora Magazine. The series profiles Fedora users and how they use Fedora to get things done. Contact us on the [feedback form][3] to express your interest in becoming a interviewee.
|
||||
|
||||
### Who is Joe Doss?
|
||||
|
||||
Joe Doss lives in Chicago, Illinois USA and his favorite food is pizza. He is the Director of Engineering Operations and Kenna Security, Inc. Doss describes his employer this way: “Kenna uses data science to help enterprises combine their infrastructure and application vulnerability data with exploit intelligence to measure risk, predict attacks and prioritize remediation.”
|
||||
|
||||
His first Linux distribution was Red Hat Linux 5. A friend of his showed him a computer that wasn’t running Windows. Doss thought it was just a program to install on Windows when his friend gave him a Red Hat Linux 5 install disk. “I proceeded to install this Linux ‘program’ on my Father’s PC,” he says. Luckily for Doss, his father supported his interest in computers. “I ended up totally wiping out the Windows 95 install as a result and this was how I got my first computer.”
|
||||
|
||||
At Kenna, Doss’ group makes use of Fedora and [Ansible][4]: “We run Fedora Cloud in multiple VPC deployments in AWS and Google Compute with over 200 virtual machines. We use Ansible to automate everything we do with Fedora.”
|
||||
|
||||
Doss brews beer at home and contributes to open source in his free time. He also has a cat named Tibby. “I rescued Tibby off the street the Hyde Park neighborhood of Chicago when she was 7 months old. She is not very smart, but she makes up for that with cuteness.” His favorite place to visit is his childhood home of Michigan, but Doss says, “anywhere with a warm beach, a cool drink, and the ocean is pretty nice too.”
|
||||
|
||||
![Tibby the cute cat!][5]
|
||||
|
||||
### The Fedora community
|
||||
|
||||
Doss became involved with Fedora and the Fedora community through his job at Kenna Security. When he first joined the company they were using Ubuntu and Chef in production. There was a desire to make the infrastructure more reproducible and reliable, and he says, “I was able to greenfield our deployments with Fedora Cloud and Ansible.” This project got him involved in the Fedora Cloud release.
|
||||
|
||||
When asked about his first impression of the Fedora community, Doss said, “Overwhelming to be honest. There is so much going on and it is hard to figure out who are the stakeholders of each part of Fedora.” Once he figured out who he needed to talk to he found the community very welcoming and super supportive.
|
||||
|
||||
One of the ideas he had to improve the community was to unite the various projects and team under on bug tracking tool and community resource. “Pagure, Bugzilla, Github, Fedora Forums, Discourse Forums, Mailing lists… it is all over the place and hard to navigate at first.” Despite the initial complexity of becoming familiar with the Fedora Project, Doss feels it is amazingly rewarding to be involved. “It feels awesome it to be apart of a Linux distro that impacts so many people in very positive ways. You can make a difference.”
|
||||
|
||||
Doss called out Dusty Mabe at Red Hat for helping him become involved, saying Dusty “has been an amazing mentor and resource for enabling me to contribute back to Fedora.”
|
||||
|
||||
Doss has an interesting way of explaining to non-technical friends what he does. “Imagine changing the tires on a very large bus while it is going down the highway at 70 MPH and sometimes you need to get involved with the tire manufacturer to help make this process work well.” This metaphor helps people understand what replacing 200-plus VMs across more than five production VPCs in AWS and Google Compute with every Fedora release.
|
||||
|
||||
Doss drew my attention to one specific incident with Fedora 29 and Vagrant. “Recently we encountered an issue where Vagrant wouldn’t set the hostname on a Fresh Fedora 29 Beta VM. This was due to Fedora 29 Cloud no longer shipping the network service stub in favor of NetworkManager. This led to me working with a colleague at Kenna Security to send a patch upstream to the Vagrant project to help their developers produce a fix for Fedora 29. Vagrant usage with Fedora is a very large part of our development cycle at Kenna, and having this broken before the Fedora 29 release would have impacted us a lot.” As Doss said, “Sometimes you need to help make the tires before they go on the bus.”
|
||||
|
||||
Doss is the [COPR][6] Fedora, RHEL, and CentOS package maintainer for [WireGuard VPN][7]. “The CentOS repo just went over 60 thousand downloads last month which is pretty awesome.”
|
||||
|
||||
### What Hardware?
|
||||
|
||||
Doss uses Fedora 29 cloud in the over five VPC deployments in AWS and Google computer. At home he has a SuperMicro SYS-5019A-FTN4 1U Server that runs Fedora 29 Server with Openshift OKD installed on it. His laptops are all Lenovo. “For Laptops I use a ThinkPad T460s for work and a ThinkPad 25 at home. Both have Fedora 29 installed. ThinkPads are the best with Fedora.”
|
||||
|
||||
### What Software?
|
||||
|
||||
Doss used GNOME 3 as his preferred desktop on Fedora Workstation. “I use Sublime Text 3 for my text editor on the desktop or vim on servers.” For development and testing he uses Vagrant. “Ansible is what I use for any kind of automation with Fedora. I maintain an [Ansible playbook][8] for setting up my workstation.”
|
||||
|
||||
### Ansible
|
||||
|
||||
I asked Doss if he had advice for people trying to learn Ansible.
|
||||
|
||||
“Start small. Automate the stuff that makes your life easier, but don’t over complicate it. [Ansible Galaxy][9] is a great resource to get things done quickly, but if you truly want to learn how to use Ansible, writing your own roles and playbooks the path I would take.
|
||||
|
||||
“I have helped a lot of my coworkers that have joined my Operations team at Kenna get up to speed on using Ansible by buying them a copy of [Ansible for Devops][10] by Jeff Geerling. This book will give anyone new to Ansible the foundation they need to start using it everyday. #ansible on Freenode is a great resource as well along with the [official Ansible docs][11].”
|
||||
|
||||
Doss also said, “Knowing what to automate is most likely the most difficult thing to master without over complicating things. Debugging complex playbooks and roles is a close second.”
|
||||
|
||||
### Home lab
|
||||
|
||||
He recommended setting up a home lab. “At Kenna and at home I use [Vagrant][12] with the [Vagrant-libvirt plugin][13] for developing Ansible roles and playbooks. You can iterate quickly to build your roles and playbooks on your laptop with your favorite editor and run _vagrant provision_ to run your playbook. Quick feedback loop and the ability to burn down your Vagrant VM and start over quickly is an amazing workflow. Below is a sample Vagrant file that I keep handy to spin up a Fedora VM to test my playbooks.”
|
||||
|
||||
```
|
||||
-- mode: ruby --
|
||||
vi: set ft=ruby :
|
||||
Vagrant.configure(2) do |config|
|
||||
config.vm.provision "shell", inline: "dnf install nfs-utils rpcbind @development-tools @ansible-node redhat-rpm-config gcc-c++ -y"
|
||||
config.ssh.forward_agent = true
|
||||
config.vm.define "f29", autostart: false do |f29|
|
||||
f29.vm.box = "fedora/29-cloud-base"
|
||||
f29.vm.hostname = "f29.example.com"
|
||||
f29.vm.provider "libvirt" do |vm|
|
||||
vm.memory = 2048
|
||||
vm.cpus = 2
|
||||
vm.driver = "kvm"
|
||||
vm.nic_model_type = "e1000"
|
||||
end
|
||||
config.vm.synced_folder '.', '/vagrant', disabled: true
|
||||
|
||||
config.vm.provision "ansible" do |ansible|
|
||||
ansible.groups = {
|
||||
}
|
||||
ansible.playbook = "playbooks/main.yml"
|
||||
ansible.inventory_path = "inventory/development"
|
||||
ansible.extra_vars = {
|
||||
ansible_python_interpreter: "/usr/bin/python3"
|
||||
}
|
||||
# ansible.verbose = 'vvv' end
|
||||
end
|
||||
end
|
||||
```
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://fedoramagazine.org/joe-doss-how-do-you-fedora/
|
||||
|
||||
作者：[Charles Profitt][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://fedoramagazine.org/author/cprofitt/
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://fedoramagazine.org/wp-content/uploads/2019/03/IMG_20181029_121944-816x345.jpg
|
||||
[2]: https://fedoramagazine.org/tag/how-do-you-fedora/
|
||||
[3]: https://fedoramagazine.org/submit-an-idea-or-tip/
|
||||
[4]: https://ansible.com
|
||||
[5]: https://fedoramagazine.org/wp-content/uploads/2019/04/IMG_20181231_110920_fixed.jpg
|
||||
[6]: https://copr.fedorainfracloud.org/coprs/jdoss/wireguard/
|
||||
[7]: https://www.wireguard.com/install/
|
||||
[8]: https://github.com/jdoss/fedora-workstation
|
||||
[9]: https://galaxy.ansible.com/
|
||||
[10]: https://www.ansiblefordevops.com/
|
||||
[11]: https://docs.ansible.com/ansible/latest/index.html
|
||||
[12]: http://www.vagrantup.com/
|
||||
[13]: https://github.com/vagrant-libvirt/vagrant-libvirt%20plugin
|
||||
@@ -0,0 +1,116 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (Linux Server Hardening Using Idempotency with Ansible: Part 2)
|
||||
[#]: via: (https://www.linux.com/blog/linux-server-hardening-using-idempotency-ansible-part-2)
|
||||
[#]: author: (Chris Binnie https://www.linux.com/users/chrisbinnie)
|
||||
|
||||
Linux Server Hardening Using Idempotency with Ansible: Part 2
|
||||
======
|
||||
|
||||
![][1]
|
||||
|
||||
[Creative Commons Zero][2]
|
||||
|
||||
In the first part of this series, we introduced something called idempotency, which can provide the ongoing improvements to your server estate’s security posture. In this article, we’ll get a little more hands-on with a look at some specific Ansible examples.
|
||||
|
||||
### Shopping List
|
||||
|
||||
You will need some Ansible experience before being able to make use of the information that follows. Rather than run through the installation and operation of Ansible let’s instead look at some of the idempotency playbook’s content.
|
||||
|
||||
As mentioned earlier there might be hundreds of individual system tweaks to make on just one type of host so we’ll only explore a few suggested Ansible tasks and how I like to structure the Ansible role responsible for the compliance and hardening. You have hopefully picked up on the fact that the devil is in the detail and you should absolutely, unequivocally, understand to as high a level of detail as possible, about the permutations of making changes to your server OS.
|
||||
|
||||
Be aware that I will mix and match between OSs in the Ansible examples that follow. Many examples are OS agnostic but as ever you should pay close attention to the detail. Obvious changes like “apt” to “yum” for the package manager is a given.
|
||||
|
||||
Inside a “tasks” file under our Ansible “hardening” role, or whatever you decide to name it, these named tasks represent the areas of a system with some example code to offer food for thought. In other words, each section that follows will probably be a single YAML file, such as “accounts.yml”, and each will have with varying lengths and complexity.
|
||||
|
||||
Let’s look at some examples with ideas about what should go into each file to get you started. The contents of each file that follow are just the very beginning of a checklist and the following suggestions are far from exhaustive.
|
||||
|
||||
#### SSH Server
|
||||
|
||||
This is the application that almost all engineers immediately look to harden when asked to secure a server. It makes sense as SSH (the OpenSSH package in many cases) is usually only one of a few ports intentionally prised open and of course allows direct access to the command line. The level of hardening that you should adopt is debatable. I believe in tightening the daemon as much as possible without disruption and would usually make around fifteen changes to the standard OpenSSH server config file, “sshd_config”. These changes would include pulling in a MOTD banner (Message Of The Day) for legal compliance (warning of unauthorised access and prosecution), enforcing the permissions on the main SSHD files (so they can’t be tampered with by lesser-privileged users), ensuring the “root” user can’t log in directly, setting an idle session timeout and so on.
|
||||
|
||||
Here’s a very simple Ansible example that you can repeat within other YAML files later on, focusing on enforcing file permissions on our main, critical OpenSSH server config file. Note that you should carefully check every single file that you hard-reset permissions on before doing so. This is because there are horrifyingly subtle differences between Linux distributions. Believe me when I say that it’s worth checking first.
|
||||
|
||||
name: Hard reset permissions on sshd server file
|
||||
|
||||
file: owner=root group=root mode=0600 path=/etc/ssh/sshd_config
|
||||
|
||||
To check existing file permissions I prefer this natty little command for the job:
|
||||
|
||||
```
|
||||
$ stat -c "%a %n" /etc/ssh/sshd_config
|
||||
|
||||
644 /etc/ssh/sshd_config
|
||||
```
|
||||
|
||||
As our “stat” command shows our Ansible snippet would be an improvement to the current permissions because 0600 means only the “root” user can read and write to that file. Other users or groups can’t even read that file which is of benefit because if we’ve made any mistakes in securing SSH’s config they can’t be discovered as easily by less-privileged users.
|
||||
|
||||
#### System Accounts
|
||||
|
||||
At a simple level this file might define how many users should be on a standard server. Usually a number of users who are admins have home directories with public keys copied into them. However this file might also include performing simple checks that the root user is the only system user with the all-powerful superuser UID 0; in case an attacker has altered user accounts on the system for example.
|
||||
|
||||
#### Kernel
|
||||
|
||||
Here’s a file that can grow arms and legs. Typically I might affect between fifteen and twenty sysctl changes on an OS which I’m satisfied won’t be disruptive to current and, all going well, any future uses of a system. These changes are again at your discretion and, at my last count (as there’s between five hundred and a thousand configurable kernel options using sysctl on a Debian/Ubuntu box) you might opt to split off these many changes up into different categories.
|
||||
|
||||
Such categories might include network stack tuning, stopping core dumps from filling up disk space, disabling IPv6 entirely and so on. Here’s an Ansible example of logging network packets that shouldn’t been routed out onto the Internet, namely those packets using spoofed private IP Addresses, called “martians”.
|
||||
|
||||
name: Keep track of traffic that shouldn’t be routed onto the Internet
|
||||
|
||||
lineinfile: dest="/etc/sysctl.conf" line="{{item.network}}" state=present
|
||||
|
||||
with_items:
|
||||
|
||||
\- { network: 'net.ipv4.conf.all.log_martians = 1' }
|
||||
|
||||
\- { network: 'net.ipv4.conf.default.log_martians = 1' }
|
||||
|
||||
Pay close attention that you probably don’t want to use the file “/etc/sysctl.conf” but create a custom file under the directory “/etc/sysctl.d/” or similar. Again, check your OS’s preference, usually in the comments of the pertinent files. If you’ve not seen martian packets being enabled before then type “dmesg” (sometimes only as the “root” user) to view kernel messages and after a week or two of logging being in place you’ll probably see some traffic polluting your logs. It’s much better to know how attackers are probing your servers than not. A few log entries for reference can only be of value. When it comes to looking after servers, ignorance is certainly not bliss.
|
||||
|
||||
#### Network
|
||||
|
||||
As mentioned you might want to include hardening the network stack within your kernel.yml file, depending on whether there’s many entries or not, or simply for greater clarity. For your network.yml file have a think about stopping old-school broadcast attacks flooding your LAN and ICMP oddities from changing your routing in addition.
|
||||
|
||||
#### Services
|
||||
|
||||
Usually I would stop or start miscellaneous system services (and potentially applications) within this Ansible file. If there weren’t many services then rather than also using a “cron.yml” file specifically for “cron” hardening I’d include those here too.
|
||||
|
||||
There’s a bundle of changes you can make around cron’s file permissions etc. If you haven’t come across it, on some OSs, there’s a “cron.deny” file for example which blacklists certain users from accessing the “crontab” command. Additionally you also have a multitude of cron directories under the “/etc” directory which need permissions enforced and improved, indeed along with the file “/etc/crontab” itself. Once again check with your OS’s current settings before altering these or “bad things” ™ might happen to your uptime.
|
||||
|
||||
In terms of miscellaneous services being purposefully stopped and certain services, such as system logging which is imperative to a healthy and secure system, have a quick look at the Ansible below which I might put in place for syslog as an example.
|
||||
|
||||
name: Insist syslog is definitely installed (so we can receive upstream logs)
|
||||
|
||||
apt: name=rsyslog state=present
|
||||
|
||||
name: Make sure that syslog starts after a reboot
|
||||
|
||||
service: name=rsyslog state=started enabled=yes
|
||||
|
||||
#### IPtables
|
||||
|
||||
The venerable Netfilter which, from within the Linux kernel offers the IPtables software firewall the ability to filter network packets in an exceptionally sophisticated manner, is a must if you can enable it sensibly. If you’re confident that each of your varying flavours of servers (whether it’s a webserver, database server and so on) can use the same IPtables config then copy a file onto the filesystem via Ansible and make sure it’s always loaded up using this YAML file.
|
||||
|
||||
Next time, we’ll wrap up our look at specific system suggestions and talk a little more about how the playbook might be used.
|
||||
|
||||
Chris Binnie’s latest book, Linux Server Security: Hack and Defend, shows you how to make your servers invisible and perform a variety of attacks. You can find out more about DevSecOps, containers and Linux security on his website: [https://www.devsecops.cc][3]
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.linux.com/blog/linux-server-hardening-using-idempotency-ansible-part-2
|
||||
|
||||
作者：[Chris Binnie][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://www.linux.com/users/chrisbinnie
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://www.linux.com/sites/lcom/files/styles/rendered_file/public/artificial-intelligence-3382507_1280.jpg?itok=PHazitpd
|
||||
[2]: /LICENSES/CATEGORY/CREATIVE-COMMONS-ZERO
|
||||
[3]: https://www.devsecops.cc/
|
||||
@@ -0,0 +1,36 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (What's your primary backup strategy for the /home directory in Linux?)
|
||||
[#]: via: (https://opensource.com/poll/19/4/backup-strategy-home-directory-linux)
|
||||
[#]: author: ( https://opensource.com/users/dboth/users/don-watkins/users/greg-p)
|
||||
|
||||
What's your primary backup strategy for the /home directory in Linux?
|
||||
======
|
||||
|
||||
![Linux keys on the keyboard for a desktop computer][1]
|
||||
|
||||
I frequently upgrade to newer releases of Fedora, which is my primary distribution. I also upgrade other distros but much less frequently. I have also had many crashes of various types over the years, including a large portion of self-inflicted ones. Past experience with data loss has made me very aware of the need for good backups.
|
||||
|
||||
I back up many parts of my Linux hosts but my **/home** directory is especially important. Losing any of the data in **/home** on my primary workstation due to a crash or an upgrade could be disastrous.
|
||||
|
||||
My backup strategy for **/home** is to back up everything every day. There are other things on every Linux system to back up but **/home **is the center of everything I do on my workstation. I keep my documents and financial records there as well as off-line emails, address books for different apps, calendar and task data, and most importantly for me these days, the working copies of my next two Linux books.
|
||||
|
||||
I can think of a number of approaches to doing backups and restores of **/home** which would allow an easy and complete recovery after a data loss ranging from a single file to the entire directory. Which approach do you take? Which tools do you use?
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/poll/19/4/backup-strategy-home-directory-linux
|
||||
|
||||
作者：[][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://opensource.com/users/dboth/users/don-watkins/users/greg-p
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/linux_keyboard_desktop.png?itok=I2nGw78_ (Linux keys on the keyboard for a desktop computer)
|
||||
@@ -0,0 +1,100 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (Working with Microsoft Exchange from your Linux Desktop)
|
||||
[#]: via: (https://itsfoss.com/microsoft-exchange-linux-desktop/)
|
||||
[#]: author: (It's FOSS Community https://itsfoss.com/author/itsfoss/)
|
||||
|
||||
Working with Microsoft Exchange from your Linux Desktop
|
||||
======
|
||||
|
||||
Recently I had to do some research (and even magic) to be able to work on my Ubuntu Desktop with Exchange Mail Server from my current employer. I am going to share my experience with you.
|
||||
|
||||
### Microsoft Exchange on Linux desktop
|
||||
|
||||
I guess many readers might feel confused, I mean, it shouldn’t be that hard if you simply use [Thunderbird][1] or any other [Linux email client][2] with your Office365 Exchange Account, right? Well, for better or for worse it was not this case for me.
|
||||
|
||||
Here’s my ordeal and what I did to make Microsoft Exchange work on my Linux desktop.
|
||||
|
||||
![][3]
|
||||
|
||||
#### The initial problem, no Office365
|
||||
|
||||
The first problem encountered in my situation was that we don’t currently use Office365 like probably majority of current people does for hosting their Exchange accounts, we currently use an on premises Exchange server and a very old version of it.
|
||||
|
||||
So, this means I didn’t have the luxury of using automatic configuration that comes in majority of email clients to simply connect to Office365.
|
||||
|
||||
#### Webmail is always an option… right?
|
||||
|
||||
Short answer is yes, however, as I mentioned we are using Exchange 2010, so the webmail interface is not only outdated, it even won’t allow you to have a decent email signature as it has a limit of characters in webmail configuration, so I needed to use an email client if I really wanted to be able to use the email the way I needed.
|
||||
|
||||
#### Another problem, I am picky for my email client
|
||||
|
||||
I am a regular Google user, I have been using GMail for the past 14 years as my personal email, so I really like how it looks and works. I actually use the webmail as I don’t like to be tied to my email client or even my computer device, if something happens and I need to switch to a newer device I don’t want to have to copy things over, I just want things to be there waiting for me to use them.
|
||||
|
||||
This leads me not liking Thunderbird, K-9 or Evolution Mail clients. All of these are capable of being connected to Exchange servers (one way or the other) but again, they don’t meet the standard of a clean, easy and modern GUI I wanted plus they couldn’t even manage my Exchange calendar well (which was a real deal breaker for me).
|
||||
|
||||
#### Found some options as email clients!
|
||||
|
||||
After some other research I found there were a couple of options for email clients that I could use and that actually would work the way I expected.
|
||||
|
||||
These were: [Hiri][4], which had a very modern and innovative user interface and had Exchange Server capabilities and there also was [Mailspring][5] which is a fork of an old foe ([Nylas Mail][6]) and which was my real favorite.
|
||||
|
||||
However, Mailspring couldn’t connect directly to an Exchange server (using Exchange’s protocol) unless you use Office365, it required [IMAP][7] (another luxury!) and the IT department at my office was reluctant to activate IMAP for “security reasons”.
|
||||
|
||||
Hiri is a good option but it’s not free.
|
||||
|
||||
#### No IMAP, no Office365, game over? Not yet!
|
||||
|
||||
I have to confess, I was really ready to give up and simply use the old webmail and learn to live with it, however, I gave a last shot on my research capabilities and I found a possible solution: what if I had a way to put a “man in the middle”? What if I was able to make the IMAP to run locally on my computer while my computer simply pull the emails via Exchange protocol? It was a long shot but, could work…
|
||||
|
||||
So I started looking here and there and found this [DavMail][8], which works as a Gateway to “talk” with an Exchange server and then locally provide you whatever you need in order to use it. Basically it was like a “translator” between by computer and the Exchange and then provided me with whatever service I needed.
|
||||
|
||||
![DavMail Settings][9]
|
||||
|
||||
So basically I only had to give DavMail my Exchange Server’s URL (even OWA URL) and set whatever ports I wanted on my local computer to be the new ports where my email client could connect.
|
||||
|
||||
This way I was free to basically use ANY client I wanted, at least any client which was capable of using IMAP protocol would work, as long as I configure the same ports I set up as my local ports.
|
||||
|
||||
![Mailspring working my office’s on premises Exchange. Information has been blurred due to non-disclosure agreement at my office.][10]
|
||||
|
||||
And that was it! I was able to use MailSpring (which is my preferred choice for email client) under my non favorable conditions.
|
||||
|
||||
#### Bonus point: this is a multi-platform solution!
|
||||
|
||||
What’s best is that this solution will work for any platform! So if you have the same problem while using Windows or macOS, DavMail has a version for all tastes!
|
||||
|
||||
![avatar][11]
|
||||
|
||||
![avatar][11]
|
||||
|
||||
### Helder Martins
|
||||
|
||||
Systems Engineer, technology evangelist, Ubuntu user, Linux enthusiast, father and husband.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://itsfoss.com/microsoft-exchange-linux-desktop/
|
||||
|
||||
作者：[It's FOSS Community][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://itsfoss.com/author/itsfoss/
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://www.thunderbird.net/en-US/
|
||||
[2]: https://itsfoss.com/best-email-clients-linux/
|
||||
[3]: https://i1.wp.com/itsfoss.com/wp-content/uploads/2019/04/microsoft-exchange-linux-desktop.png?resize=800%2C450&ssl=1
|
||||
[4]: https://www.hiri.com/
|
||||
[5]: https://getmailspring.com/
|
||||
[6]: https://itsfoss.com/n1-open-source-email-client/
|
||||
[7]: https://en.wikipedia.org/wiki/Internet_Message_Access_Protocol
|
||||
[8]: http://davmail.sourceforge.net/
|
||||
[9]: https://i1.wp.com/itsfoss.com/wp-content/uploads/2019/04/davmail-exchange-settings.png?resize=800%2C597&ssl=1
|
||||
[10]: https://i2.wp.com/itsfoss.com/wp-content/uploads/2019/04/davmail-exchange-settings-1.jpg?ssl=1
|
||||
[11]: https://i2.wp.com/itsfoss.com/wp-content/uploads/2019/04/helder-martins-1.jpeg?ssl=1
|
||||
@@ -0,0 +1,354 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (12 Single Board Computers: Alternative to Raspberry Pi)
|
||||
[#]: via: (https://itsfoss.com/raspberry-pi-alternatives/)
|
||||
[#]: author: (Ankush Das https://itsfoss.com/author/ankush/)
|
||||
|
||||
12 Single Board Computers: Alternative to Raspberry Pi
|
||||
======
|
||||
|
||||
_**Brief: Looking for a Raspberry Pi alternative? Here are some other single board computers to satisfy your DIY cravings.**_
|
||||
|
||||
Raspberry Pi is the most popular single board computer right now. You can use it for your DIY projects or can use it as a cost effective system to learn coding or maybe utilize a [media server software][1] on it to stream media at your convenience.
|
||||
|
||||
You can do a lot of things with Raspberry Pi but it is not the ultimate solution for all kinds of tinkerers. Some might be looking for a cheaper board and some might be on the lookout for a powerful one.
|
||||
|
||||
Whatever be the case, we do need Raspberry Pi alternatives for a variety of reasons. So, in this article, we will talk about the best ten single board computers that we think are the best Raspberry Pi alternatives.
|
||||
|
||||
![][2]
|
||||
|
||||
### Raspberry Pi alternatives to satisfy your DIY craving
|
||||
|
||||
The list is in no particular order of ranking. Some of the links here are affiliate links. Please read our [affiliate policy][3].
|
||||
|
||||
#### 1\. Onion Omega2+
|
||||
|
||||
![][4]
|
||||
|
||||
For just **$13** , the Omega2+ is one of the cheapest IoT single board computers you can find out there. It runs on LEDE (Linux Embedded Development Environment) Linux OS – a distribution based on [OpenWRT][5].
|
||||
|
||||
Its form factor, cost, and the flexibility that comes from running a customized version of Linux OS makes it a perfect fit for almost any type of IoT applications.
|
||||
|
||||
You can find [Onion Omega kit on Amazon][6] or order from their own website that would cost you extra shipping charges.
|
||||
|
||||
**Key Specifications**
|
||||
|
||||
* MT7688 SoC
|
||||
* 2.4 GHz IEEE 802.11 b/g/n WiFi
|
||||
* 128 MB DDR2 RAM
|
||||
* 32 MB on-board flash storage
|
||||
* MicroSD Slot
|
||||
* USB 2.0
|
||||
* 12 GPIO Pins
|
||||
|
||||
|
||||
|
||||
[Visit WEBSITE
|
||||
][7]
|
||||
|
||||
#### 2\. NVIDIA Jetson Nano Developer Kit
|
||||
|
||||
![][8]
|
||||
|
||||
This is a very unique and interesting Raspberry Pi alternative from NVIDIA for just **$99**. Yes, it’s not something that everyone can make use of – but for a specific group of tinkerers or developers.
|
||||
|
||||
NVIDIA explains it for the following use-case:
|
||||
|
||||
> NVIDIA® Jetson Nano™ Developer Kit is a small, powerful computer that lets you run multiple neural networks in parallel for applications like image classification, object detection, segmentation, and speech processing. All in an easy-to-use platform that runs in as little as 5 watts.
|
||||
>
|
||||
> nvidia
|
||||
|
||||
So, basically, if you are into AI and deep learning, you can make use of the developer kit. If you are curious, the production compute module of this will be arriving in June 2019.
|
||||
|
||||
**Key Specifications:**
|
||||
|
||||
* CPU: Quad-core ARM A57 @ 1.43 GHz
|
||||
* GPU: 128-core Maxwell
|
||||
* RAM: 4 GB 64-bit LPDDR4 25.6 GB/s
|
||||
* Display: HDMI 2.0
|
||||
* 4 x USB 3.0 and eDP 1.4
|
||||
|
||||
|
||||
|
||||
[VISIT WEBSITE
|
||||
][9]
|
||||
|
||||
#### 3\. ASUS Tinker Board S
|
||||
|
||||
![][10]
|
||||
|
||||
ASUS Tinker Board S isn’t the most affordable Raspberry Pi alternative at **$82** (on [Amazon][11]) but it is a powerful alternative. It features the same 40-pin connector that you’d normally find in the standard Raspberry Pi 3 Model but offers a powerful processor and a GPU.Also, the size of the Tinker Board S is exactly the same as a standard Raspberry Pi 3.
|
||||
|
||||
The main highlight of this board is the presence of 16 GB [eMMC][12] (in layman terms, it has got SSD-like storage on board that makes it faster while working on it).
|
||||
|
||||
**Key Specifications:**
|
||||
|
||||
* Rockchip Quad-Core RK3288 processor
|
||||
* 2 GB DDR3 RAM
|
||||
* Integrated Graphics Processor
|
||||
* ARM® Mali™-T764 GPU
|
||||
* 16 GB eMMC
|
||||
* MicroSD Card Slot
|
||||
* 802.11 b/g/n, Bluetooth V4.0 + EDR
|
||||
* USB 2.0
|
||||
* 28 GPIO pins
|
||||
* HDMI Interface
|
||||
|
||||
|
||||
|
||||
[Visit website
|
||||
][13]
|
||||
|
||||
#### 4\. ClockworkPi
|
||||
|
||||
![][14]
|
||||
|
||||
Clockwork Pi is usually a part of the [GameShell Kit][15] if you are looking to assemble a modular retro gaming console. However, you can purchase the board separately for $49.
|
||||
|
||||
Its compact size, WiFi connectivity, and the presence of micro HDMI port make it a great choice for a lot of things.
|
||||
|
||||
**Key Specifications:**
|
||||
|
||||
* Allwinner R16-J Quad-core Cortex-A7 CPU @1.2GHz
|
||||
* Mali-400 MP2 GPU
|
||||
* RAM: 1GB DDR3
|
||||
* WiFi & Bluetooth v4.0
|
||||
* Micro HDMI output
|
||||
* MicroSD Card Slot
|
||||
|
||||
|
||||
|
||||
[visit website
|
||||
][16]
|
||||
|
||||
#### 5\. Arduino Mega 2560
|
||||
|
||||
![][17]
|
||||
|
||||
If you are into robotic projects or you want something for a 3D printer – Arduino Mega 2560 will be a handy replacement to Raspberry Pi. Unlike Raspberry Pi, it is based on a microcontroller and not a microprocessor.
|
||||
|
||||
It would cost you $38.50 on their [official site][18] and and around [$33 on Amazon][19].
|
||||
|
||||
**Key Specifications:**
|
||||
|
||||
* Microcontroller: ATmega2560
|
||||
* Clock Speed: 16 MHz
|
||||
* Digital I/O Pins: 54
|
||||
* Analog Input Pins: 16
|
||||
* Flash Memory: 256 KB of which 8 KB used by bootloader
|
||||
|
||||
|
||||
|
||||
[visit website
|
||||
][18]
|
||||
|
||||
#### 6\. Rock64 Media Board
|
||||
|
||||
![][20]
|
||||
|
||||
For the same investment as you would on a Raspberry Pi 3 B+, you will be getting a faster processor and double the memory on Rock64 Media Board. In addition, it also offers a cheaper alternative to Raspberry Pi if you want the 1 GB RAM model – which would cost $10 less.
|
||||
|
||||
Unlike Raspberry Pi, you do not have wireless connectivity support here but the presence of USB 3.0 and HDMI 2.0 does make a good difference if that matters to you.
|
||||
|
||||
**Key Specifications:**
|
||||
|
||||
* Rockchip RK3328 Quad-Core ARM Cortex A53 64-Bit Processor
|
||||
* Supports up to 4GB 1600MHz LPDDR3 RAM
|
||||
* eMMC module socket
|
||||
* MicroSD Card slot
|
||||
* USB 3.0
|
||||
* HDMI 2.0
|
||||
|
||||
|
||||
|
||||
[visit website
|
||||
][21]
|
||||
|
||||
#### 7\. Odroid-XU4
|
||||
|
||||
![][22]
|
||||
|
||||
Odroid-XU4 is the perfect alternative to Raspberry Pi if you have room to spend a little more ($80-$100 or even lower, depending on the store/availability).
|
||||
|
||||
It is indeed a powerful replacement and technically a bit smaller in size. The support for eMMC and USB 3.0 makes it faster to work with.
|
||||
|
||||
**Key Specifications:**
|
||||
|
||||
* Samsung Exynos 5422 Octa ARM Cortex™-A15 Quad 2Ghz and Cortex™-A7 Quad 1.3GHz CPUs
|
||||
* 2Gbyte LPDDR3 RAM
|
||||
* GPU: Mali-T628 MP6
|
||||
* USB 3.0
|
||||
* HDMI 1.4a
|
||||
* eMMC 5.0 module socket
|
||||
* MicroSD Card Slot
|
||||
|
||||
|
||||
|
||||
[visit website
|
||||
][23]
|
||||
|
||||
#### 8\. **PocketBeagle**
|
||||
|
||||
![][24]
|
||||
|
||||
It is an incredibly small SBC – almost similar to the Raspberry Pi Zero. However, it would cost you the same as that of a full-sized Raspberry Pi 3 model. The main highlight here is that you can use it as a USB key-fob and then access the Linux terminal to work on it.
|
||||
|
||||
**Key Specifications:**
|
||||
|
||||
* Processor: Octavo Systems OSD3358 1GHz ARM® Cortex-A8
|
||||
* RAM: 512 MB DDR3
|
||||
* 72 expansion pin headers
|
||||
* microUSB
|
||||
* USB 2.0
|
||||
|
||||
|
||||
|
||||
[visit website
|
||||
][25]
|
||||
|
||||
#### 9\. Le Potato
|
||||
|
||||
![][26]
|
||||
|
||||
Le Potato by [Libre Computer][27], also identified by its model number AML-S905X-CC. It would [cost you $45][28].
|
||||
|
||||
If you want double the memory along with HDMI 2.0 interface by spending a bit more than a Raspberry Pi – this would be the perfect choice. Although, you won’t find wireless connectivity baked in.
|
||||
|
||||
**Key Specifications:**
|
||||
|
||||
* Amlogic S905X SoC
|
||||
* 2GB DDR3 SDRAM
|
||||
* USB 2.0
|
||||
* HDMI 2.0
|
||||
* microUSB
|
||||
* MicroSD Card Slot
|
||||
* eMMC Interface
|
||||
|
||||
|
||||
|
||||
[visit website
|
||||
][29]
|
||||
|
||||
#### 10\. Banana Pi M64
|
||||
|
||||
![][30]
|
||||
|
||||
It comes loaded with 8 Gigs of eMMC – which is the key highlight of this Raspberry Pi alternative. For the very same reason, it would cost you $60.
|
||||
|
||||
The presence of HDMI interface makes it 4K-ready. In addition, Banana Pi offers a lot more variety of open source SBCs as an alternative to Raspberry Pi.
|
||||
|
||||
**Key Specifications:**
|
||||
|
||||
* 1.2 Ghz Quad-Core ARM Cortex A53 64-Bit Processor-R18
|
||||
* 2GB DDR3 SDRAM
|
||||
* 8 GB eMMC
|
||||
* WiFi & Bluetooth
|
||||
* USB 2.0
|
||||
* HDMI
|
||||
|
||||
|
||||
|
||||
[visit website
|
||||
][31]
|
||||
|
||||
#### 11\. Orange Pi Zero
|
||||
|
||||
![][32]
|
||||
|
||||
The Orange Pi Zero is an incredibly cheap alternative to Raspberry Pi. You will be able to get it for almost $10 on Aliexpress or Amazon. For a [little more investment, you can get 512 MB RAM][33].
|
||||
|
||||
If that isn’t sufficient, you can also go for Orange Pi 3 with better specifications which will cost you around $25.
|
||||
|
||||
**Key Specifications:**
|
||||
|
||||
* H2 Quad-core Cortex-A7
|
||||
* Mali400MP2 GPU
|
||||
* RAM: Up to 512 MB
|
||||
* TF Card support
|
||||
* WiFi
|
||||
* USB 2.0
|
||||
|
||||
|
||||
|
||||
[Visit website
|
||||
][34]
|
||||
|
||||
#### 12\. VIM 2 SBC by Khadas
|
||||
|
||||
![][35]
|
||||
|
||||
VIM 2 by Khadas is one of the latest SBCs that you can grab with Bluetooth 5.0 on board. It [starts from $99 (the basic model) and goes up to $140][36].
|
||||
|
||||
The basic model includes 2 GB RAM, 16 GB eMMC and Bluetooth 4.1. However, the Pro/Max versions would include Bluetooth 5.0, more memory, and more eMMC storage.
|
||||
|
||||
**Key Specifications:**
|
||||
|
||||
* Amlogic S912 1.5GHz 64-bit Octa-Core CPU
|
||||
* T820MP3 GPU
|
||||
* Up to 3 GB DDR4 RAM
|
||||
* Up to 64 GB eMMC
|
||||
* Bluetooth 5.0 (Pro/Max)
|
||||
* Bluetooth 4.1 (Basic)
|
||||
* HDMI 2.0a
|
||||
* WiFi
|
||||
|
||||
|
||||
|
||||
**Wrapping Up**
|
||||
|
||||
We do know that there are different types of single board computers. Some are better than Raspberry Pi – and some scaled down versions of it for a cheaper price tag. Also, SBCs like Jetson Nano have been tailored for a specific use. So, depending on what you require – you should verify the specifications of the single board computer.
|
||||
|
||||
If you think that you know about something that is better than the ones mentioned above, feel free to let us know in the comments below.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://itsfoss.com/raspberry-pi-alternatives/
|
||||
|
||||
作者：[Ankush Das][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://itsfoss.com/author/ankush/
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://itsfoss.com/best-linux-media-server/
|
||||
[2]: https://i2.wp.com/itsfoss.com/wp-content/uploads/2019/04/raspberry-pi-alternatives.png?resize=800%2C450&ssl=1
|
||||
[3]: https://itsfoss.com/affiliate-policy/
|
||||
[4]: https://i2.wp.com/itsfoss.com/wp-content/uploads/2019/04/omega-2-plus-e1555306748755-800x444.jpg?resize=800%2C444&ssl=1
|
||||
[5]: https://openwrt.org/
|
||||
[6]: https://amzn.to/2Xj8pkn
|
||||
[7]: https://onion.io/store/omega2p/
|
||||
[8]: https://i2.wp.com/itsfoss.com/wp-content/uploads/2019/04/Jetson-Nano-e1555306350976-800x590.jpg?resize=800%2C590&ssl=1
|
||||
[9]: https://developer.nvidia.com/embedded/buy/jetson-nano-devkit
|
||||
[10]: https://i0.wp.com/itsfoss.com/wp-content/uploads/2019/04/asus-tinker-board-s-e1555304945760-800x450.jpg?resize=800%2C450&ssl=1
|
||||
[11]: https://amzn.to/2XfkOFT
|
||||
[12]: https://en.wikipedia.org/wiki/MultiMediaCard
|
||||
[13]: https://www.asus.com/in/Single-Board-Computer/Tinker-Board-S/
|
||||
[14]: https://i2.wp.com/itsfoss.com/wp-content/uploads/2019/04/clockwork-pi-e1555305016242-800x506.jpg?resize=800%2C506&ssl=1
|
||||
[15]: https://itsfoss.com/gameshell-console/
|
||||
[16]: https://www.clockworkpi.com/product-page/cpi-v3-1
|
||||
[17]: https://i2.wp.com/itsfoss.com/wp-content/uploads/2019/04/arduino-mega-2560-e1555305257633.jpg?ssl=1
|
||||
[18]: https://store.arduino.cc/usa/mega-2560-r3
|
||||
[19]: https://amzn.to/2KCi041
|
||||
[20]: https://i0.wp.com/itsfoss.com/wp-content/uploads/2019/04/ROCK64_board-e1555306092845-800x440.jpg?resize=800%2C440&ssl=1
|
||||
[21]: https://www.pine64.org/?product=rock64-media-board-computer
|
||||
[22]: https://i1.wp.com/itsfoss.com/wp-content/uploads/2019/04/odroid-xu4.jpg?fit=800%2C354&ssl=1
|
||||
[23]: https://www.hardkernel.com/shop/odroid-xu4-special-price/
|
||||
[24]: https://i0.wp.com/itsfoss.com/wp-content/uploads/2019/04/PocketBeagle.jpg?fit=800%2C450&ssl=1
|
||||
[25]: https://beagleboard.org/p/products/pocketbeagle
|
||||
[26]: https://i1.wp.com/itsfoss.com/wp-content/uploads/2019/04/aml-libre.-e1555306237972-800x514.jpg?resize=800%2C514&ssl=1
|
||||
[27]: https://libre.computer/
|
||||
[28]: https://amzn.to/2DpG3xl
|
||||
[29]: https://libre.computer/products/boards/aml-s905x-cc/
|
||||
[30]: https://i2.wp.com/itsfoss.com/wp-content/uploads/2019/04/banana-pi-m6.jpg?fit=800%2C389&ssl=1
|
||||
[31]: http://www.banana-pi.org/m64.html
|
||||
[32]: https://i2.wp.com/itsfoss.com/wp-content/uploads/2019/04/orange-pi-zero.jpg?fit=800%2C693&ssl=1
|
||||
[33]: https://amzn.to/2IlI81g
|
||||
[34]: http://www.orangepi.org/orangepizero/index.html
|
||||
[35]: https://i0.wp.com/itsfoss.com/wp-content/uploads/2019/04/khadas-vim-2-e1555306505640-800x563.jpg?resize=800%2C563&ssl=1
|
||||
[36]: https://amzn.to/2UDvrFE
|
||||
@@ -0,0 +1,75 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (Blender short film, new license for Chef, ethics in open source, and more news)
|
||||
[#]: via: (https://opensource.com/article/15/4/news-april-15)
|
||||
[#]: author: (Joshua Allen Holm (Community Moderator) https://opensource.com/users/holmja)
|
||||
|
||||
Blender short film, new license for Chef, ethics in open source, and more news
|
||||
======
|
||||
Here are some of the biggest headlines in open source in the last two
|
||||
weeks
|
||||
![][1]
|
||||
|
||||
In this edition of our open source news roundup, we take a look at the 12th Blender short film, Chef shifts away from open core toward a 100% open source license, SuperTuxKart's latest release candidate with online multiplayer support, and more.
|
||||
|
||||
### Blender Animation Studio releases Spring
|
||||
|
||||
[Spring][2], the latest short film from [Blender Animation Studio][3], premiered on April 4th. The [press release on Blender.org][4] describes _Spring_ as "the story of a shepherd girl and her dog, who face ancient spirits in order to continue the cycle of life." The development version of Blender 2.80, as well as other open source tools, were used to create this animated short film. The character and asset files for the film are available from [Blender Cloud][5], and tutorials, walkthroughs, and other instructional material are coming soon.
|
||||
|
||||
### The importance of ethics in open source
|
||||
|
||||
Reuven M. Lerner, writing for [Linux Journal][6], shares his thoughts about need for teaching programmers about ethics in an article titled [Open Source Is Winning, and Now It's Time for People to Win Too][7]. Part retrospective looking back at the history of open source and part call to action for moving forward, Lerner's article discusses many issues relevant to open source beyond just coding. He argues that when we teach kids about open source "[w]e also need to inform them of the societal parts of their work, and the huge influence and power that today's programmers have." He continues by stating "It's sometimes okay—and even preferable—for a company to make less money deliberately, when the alternative would be to do things that are inappropriate or illegal." Overall a very thought-provoking piece, Lerner makes a solid case for making sure to remember that the open source movement is about more than free code.
|
||||
|
||||
### Chef transitions from open core to open source
|
||||
|
||||
Chef, the company behind the well-known DevOps automation tool, [announced][8] that they will be release 100% of their software as open source under an Apache 2.0 license. This move marks a departure from their current [open core model][9]. Given a tendency for companies to try to move in the opposite direction, Chef's move is a big one. By operating under a fully open source model Chef builds a better, stronger relationship with the community, and the community benefits from full access to all the source code. Even developers of competing projects (and the commercial projects based on those products) benefit from being able to learn from Chef's code, as Chef can do from its open source competitors, which is one of the greatest advantages of open source; the best ideas get to win and business relationships are built around trust and quality of service, not proprietary secrets. For a more detailed look at this development, read Steven J. Vaughan-Nichols's [article for ZDNet][10].
|
||||
|
||||
### SuperTuxKart releases version 0.10 RC1 for testing
|
||||
|
||||
SuperTuxKart, the open source Mario Kart clone featuring open source mascots, is getting very close to releasing a version that supports online multi-player. On April 5th, the SuperTuxKart blog announced the release of [SuperTuxKart 0.10 Release Candidate 1][11], which needs testing before the final release. Users who want to help test the online and LAN multiplayer options can [download the game from SourceForge][12]. In addition to the new online and LAN features, SuperTuxKart 0.10 features a couple new tracks to race on; Ravenbridge Mansion replaces the old Mansion track, and Black Forest, which was an add-on track in earlier versions, is now part of the official track set.
|
||||
|
||||
#### In other news
|
||||
|
||||
* [My code is your code: Embracing the power of open sourcing][13]
|
||||
* [FOSS means kids can have a big impact][14]
|
||||
* [Open-source textbooks lighten students’ financial load][15]
|
||||
* [Developing the ultimate open source radio control transmitter][16]
|
||||
* [How does open source tech transform Government?][17]
|
||||
|
||||
|
||||
|
||||
_Thanks, as always, to Opensource.com staff members and moderators for their help this week._
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/15/4/news-april-15
|
||||
|
||||
作者：[Joshua Allen Holm (Community Moderator)][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://opensource.com/users/holmja
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/weekly_news_roundup_tv.png?itok=B6PM4S1i
|
||||
[2]: https://www.youtube.com/watch?v=WhWc3b3KhnY (Spring)
|
||||
[3]: https://blender.studio/ (Blender Animation Studio)
|
||||
[4]: https://www.blender.org/press/spring-open-movie/ (Spring Open Movie)
|
||||
[5]: https://cloud.blender.org/p/spring/ (Spring on Blender Cloud)
|
||||
[6]: https://www.linuxjournal.com/ (Linux Journal)
|
||||
[7]: https://www.linuxjournal.com/content/open-source-winning-and-now-its-time-people-win-too (Open Source Is Winning, and Now It's Time for People to Win Too)
|
||||
[8]: https://blog.chef.io/2019/04/02/chef-software-announces-the-enterprise-automation-stack/ (Introducing the New Chef: 100% Open, Always)
|
||||
[9]: https://en.wikipedia.org/wiki/Open-core_model (Wikipedia: Open-core model)
|
||||
[10]: https://www.zdnet.com/article/leading-devops-program-chef-goes-all-in-with-open-source/ (Leading DevOps program Chef goes all in with open source)
|
||||
[11]: http://blog.supertuxkart.net/2019/04/supertuxkart-010-release-candidate-1.html (SuperTuxKart 0.10 Release Candidate 1 Released)
|
||||
[12]: https://sourceforge.net/projects/supertuxkart/files/SuperTuxKart/0.10-rc1/ (SourceForge: SuperTuxKart)
|
||||
[13]: https://www.forbes.com/sites/forbestechcouncil/2019/04/10/my-code-is-your-code-embracing-the-power-of-open-sourcing/ (My code is your code: Embracing the power of open sourcing)
|
||||
[14]: https://www.linuxjournal.com/content/foss-means-kids-can-have-big-impact (FOSS means kids can have a big impact)
|
||||
[15]: https://www.schoolnewsnetwork.org/2019/04/09/open-source-textbooks-lighten-students-financial-load/ (Open-source textbooks lighten students’ financial load)
|
||||
[16]: https://hackaday.com/2019/04/03/developing-the-ultimate-open-source-radio-control-transmitter/ (Developing the ultimate open source radio control transmitter)
|
||||
[17]: https://www.openaccessgovernment.org/open-source-tech-transform/62059/ (How does open source tech transform Government?)
|
||||
@@ -0,0 +1,127 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: (geekpi)
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (Getting started with Mercurial for version control)
|
||||
[#]: via: (https://opensource.com/article/19/4/getting-started-mercurial)
|
||||
[#]: author: (Moshe Zadka (Community Moderator) https://opensource.com/users/moshez)
|
||||
|
||||
Getting started with Mercurial for version control
|
||||
======
|
||||
Learn the basics of Mercurial, a distributed version control system
|
||||
written in Python.
|
||||
![][1]
|
||||
|
||||
[Mercurial][2] is a distributed version control system written in Python. Because it's written in a high-level language, you can write a Mercurial extension with a few Python functions.
|
||||
|
||||
There are several ways to install Mercurial, which are explained in the [official documentation][3]. My favorite one is not there: using **pip**. This is the most amenable way to develop local extensions!
|
||||
|
||||
For now, Mercurial only supports Python 2.7, so you will need to create a Python 2.7 virtual environment:
|
||||
|
||||
|
||||
```
|
||||
python2 -m virtualenv mercurial-env
|
||||
./mercurial-env/bin/pip install mercurial
|
||||
```
|
||||
|
||||
To have a short command, and to satisfy everyone's insatiable need for chemistry-based humor, the command is called **hg**.
|
||||
|
||||
|
||||
```
|
||||
$ source mercurial-env/bin/activate
|
||||
(mercurial-env)$ mkdir test-dir
|
||||
(mercurial-env)$ cd test-dir
|
||||
(mercurial-env)$ hg init
|
||||
(mercurial-env)$ hg status
|
||||
(mercurial-env)$
|
||||
```
|
||||
|
||||
The status is empty since you do not have any files. Add a couple of files:
|
||||
|
||||
|
||||
```
|
||||
(mercurial-env)$ echo 1 > one
|
||||
(mercurial-env)$ echo 2 > two
|
||||
(mercurial-env)$ hg status
|
||||
? one
|
||||
? two
|
||||
(mercurial-env)$ hg addremove
|
||||
adding one
|
||||
adding two
|
||||
(mercurial-env)$ hg commit -m 'Adding stuff'
|
||||
(mercurial-env)$ hg log
|
||||
changeset: 0:1f1befb5d1e9
|
||||
tag: tip
|
||||
user: Moshe Zadka <[moshez@zadka.club][4]>
|
||||
date: Fri Mar 29 12:42:43 2019 -0700
|
||||
summary: Adding stuff
|
||||
```
|
||||
|
||||
The **addremove** command is useful: it adds any new files that are not ignored to the list of managed files and removes any files that have been removed.
|
||||
|
||||
As I mentioned, Mercurial extensions are written in Python—they are just regular Python modules.
|
||||
|
||||
This is an example of a short Mercurial extension:
|
||||
|
||||
|
||||
```
|
||||
from mercurial import registrar
|
||||
from mercurial.i18n import _
|
||||
|
||||
cmdtable = {}
|
||||
command = registrar.command(cmdtable)
|
||||
|
||||
@command('say-hello',
|
||||
[('w', 'whom', '', _('Whom to greet'))])
|
||||
def say_hello(ui, repo, **opts):
|
||||
ui.write("hello ", opts['whom'], "\n")
|
||||
```
|
||||
|
||||
A simple way to test it is to put it in a file in the virtual environment manually:
|
||||
|
||||
|
||||
```
|
||||
`$ vi ../mercurial-env/lib/python2.7/site-packages/hello_ext.py`
|
||||
```
|
||||
|
||||
Then you need to _enable_ the extension. You can start by enabling it only in the current repository:
|
||||
|
||||
|
||||
```
|
||||
$ cat >> .hg/hgrc
|
||||
[extensions]
|
||||
hello_ext =
|
||||
```
|
||||
|
||||
Now, a greeting is possible:
|
||||
|
||||
|
||||
```
|
||||
(mercurial-env)$ hg say-hello --whom world
|
||||
hello world
|
||||
```
|
||||
|
||||
Most extensions will do more useful stuff—possibly even things to do with Mercurial. The **repo** object is a **mercurial.hg.repository** object.
|
||||
|
||||
Refer to the [official documentation][5] for more about Mercurial's API. And visit the [official repo][6] for more examples and inspiration.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/19/4/getting-started-mercurial
|
||||
|
||||
作者：[Moshe Zadka (Community Moderator)][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://opensource.com/users/moshez
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/rh_003499_01_cloud21x_cc.png?itok=5UwC92dO
|
||||
[2]: https://www.mercurial-scm.org/
|
||||
[3]: https://www.mercurial-scm.org/wiki/UnixInstall
|
||||
[4]: mailto:moshez@zadka.club
|
||||
[5]: https://www.mercurial-scm.org/wiki/MercurialApi#Repositories
|
||||
[6]: https://www.mercurial-scm.org/repo/hg/file/tip/hgext
|
||||
@@ -0,0 +1,292 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (How To Enable (UP) And Disable (DOWN) A Network Interface Port (NIC) In Linux?)
|
||||
[#]: via: (https://www.2daygeek.com/enable-disable-up-down-nic-network-interface-port-linux-using-ifconfig-ifdown-ifup-ip-nmcli-nmtui/)
|
||||
[#]: author: (Magesh Maruthamuthu https://www.2daygeek.com/author/magesh/)
|
||||
|
||||
How To Enable (UP) And Disable (DOWN) A Network Interface Port (NIC) In Linux?
|
||||
======
|
||||
|
||||
You may need to run these commands based on your requirements.
|
||||
|
||||
I can tell you few examples, where you would be needed this.
|
||||
|
||||
When you add a new network interface or when you create a new virtual network interface from the original physical interface.
|
||||
|
||||
you may need to bounce these commands to bring up the new interface.
|
||||
|
||||
Also, if you made any changes or if it’s down then you need to run one of the below commands to bring them up.
|
||||
|
||||
It can be done on many ways and we would like to add best five method which we used in the article.
|
||||
|
||||
It can be done using the below five methods.
|
||||
|
||||
* **`ifconfig Command:`** The ifconfig command is used configure a network interface. It provides so many information about NIC.
|
||||
* **`ifdown/up Command:`** The ifdown command take a network interface down and the ifup command bring a network interface up.
|
||||
* **`ip Command:`** ip command is used to manage NIC. It’s replacement of old and deprecated ifconfig command. It’s similar to ifconfig command but has many powerful features which isn’t available in ifconfig command.
|
||||
* **`nmcli Command:`** nmcli is a command-line tool for controlling NetworkManager and reporting network status.
|
||||
* **`nmtui Command:`** nmtui is a curses‐based TUI application for interacting with NetworkManager.
|
||||
|
||||
|
||||
|
||||
The below output shows the available network interface card (NIC) information in my Linux system.
|
||||
|
||||
```
|
||||
# ip a
|
||||
1: lo: mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
|
||||
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
|
||||
inet 127.0.0.1/8 scope host lo
|
||||
valid_lft forever preferred_lft forever
|
||||
inet6 ::1/128 scope host
|
||||
valid_lft forever preferred_lft forever
|
||||
2: enp0s3: mtu 1500 qdisc fq_codel state UP group default qlen 1000
|
||||
link/ether 08:00:27:c2:e4:e8 brd ff:ff:ff:ff:ff:ff
|
||||
inet 192.168.1.4/24 brd 192.168.1.255 scope global dynamic noprefixroute enp0s3
|
||||
valid_lft 86049sec preferred_lft 86049sec
|
||||
inet6 fe80::3899:270f:ae38:b433/64 scope link noprefixroute
|
||||
valid_lft forever preferred_lft forever
|
||||
3: enp0s8: mtu 1500 qdisc fq_codel state UP group default qlen 1000
|
||||
link/ether 08:00:27:30:5d:52 brd ff:ff:ff:ff:ff:ff
|
||||
inet 192.168.1.3/24 brd 192.168.1.255 scope global dynamic noprefixroute enp0s8
|
||||
valid_lft 86049sec preferred_lft 86049sec
|
||||
inet6 fe80::32b7:8727:bdf2:2f3/64 scope link noprefixroute
|
||||
valid_lft forever preferred_lft forever
|
||||
```
|
||||
|
||||
### 1) How To Bring UP And Bring Down A Network Interface In Linux Using ifconfig Command?
|
||||
|
||||
The ifconfig command is used configure a network interface.
|
||||
|
||||
It is used at boot time to set up interfaces as necessary. It provides so many information about NIC. We can use ifconfig command when we need to make any changes on NIC.
|
||||
|
||||
Common Syntax for ifconfig:
|
||||
|
||||
```
|
||||
# ifconfig [NIC_NAME] Down/Up
|
||||
```
|
||||
|
||||
Run the following command to bring down the `enp0s3` interface in Linux. Make a note, you have to input your interface name instead of us.
|
||||
|
||||
```
|
||||
# ifconfig enp0s3 down
|
||||
```
|
||||
|
||||
Yes, the given interface is down now as per the following output.
|
||||
|
||||
```
|
||||
# ip a | grep -A 1 "enp0s3:"
|
||||
2: enp0s3: mtu 1500 qdisc fq_codel state DOWN group default qlen 1000
|
||||
link/ether 08:00:27:c2:e4:e8 brd ff:ff:ff:ff:ff:ff
|
||||
```
|
||||
|
||||
Run the following command to bring down the `enp0s3` interface in Linux.
|
||||
|
||||
```
|
||||
# ifconfig enp0s3 up
|
||||
```
|
||||
|
||||
Yes, the given interface is up now as per the following output.
|
||||
|
||||
```
|
||||
# ip a | grep -A 5 "enp0s3:"
|
||||
2: enp0s3: mtu 1500 qdisc fq_codel state UP group default qlen 1000
|
||||
link/ether 08:00:27:c2:e4:e8 brd ff:ff:ff:ff:ff:ff
|
||||
inet 192.168.1.4/24 brd 192.168.1.255 scope global dynamic noprefixroute enp0s3
|
||||
valid_lft 86294sec preferred_lft 86294sec
|
||||
inet6 fe80::3899:270f:ae38:b433/64 scope link noprefixroute
|
||||
valid_lft forever preferred_lft forever
|
||||
```
|
||||
|
||||
### 2) How To Enable And Disable A Network Interface In Linux Using ifdown/up Command?
|
||||
|
||||
The ifdown command take a network interface down and the ifup command bring a network interface up.
|
||||
|
||||
**Note:**It doesn’t work on new interface device name like `enpXXX`
|
||||
|
||||
Common Syntax for ifdown/ifup:
|
||||
|
||||
```
|
||||
# ifdown [NIC_NAME]
|
||||
|
||||
# ifup [NIC_NAME]
|
||||
```
|
||||
|
||||
Run the following command to bring down the `eth1` interface in Linux.
|
||||
|
||||
```
|
||||
# ifdown eth0
|
||||
```
|
||||
|
||||
Run the following command to bring down the `eth1` interface in Linux.
|
||||
|
||||
```
|
||||
# ip a | grep -A 3 "eth1:"
|
||||
3: eth1: mtu 1500 qdisc pfifo_fast state DOWN qlen 1000
|
||||
link/ether 08:00:27:d5:a0:18 brd ff:ff:ff:ff:ff:ff
|
||||
```
|
||||
|
||||
Run the following command to bring down the `eth1` interface in Linux.
|
||||
|
||||
```
|
||||
# ifup eth0
|
||||
```
|
||||
|
||||
Yes, the given interface is up now as per the following output.
|
||||
|
||||
```
|
||||
# ip a | grep -A 5 "eth1:"
|
||||
3: eth1: mtu 1500 qdisc pfifo_fast state UP qlen 1000
|
||||
link/ether 08:00:27:d5:a0:18 brd ff:ff:ff:ff:ff:ff
|
||||
inet 192.168.1.7/24 brd 192.168.1.255 scope global eth1
|
||||
inet6 fe80::a00:27ff:fed5:a018/64 scope link tentative dadfailed
|
||||
valid_lft forever preferred_lft forever
|
||||
```
|
||||
|
||||
ifup and ifdown doesn’t supporting the latest interface device `enpXXX` names. I got the below message when i ran the command.
|
||||
|
||||
```
|
||||
# ifdown enp0s8
|
||||
Unknown interface enp0s8
|
||||
```
|
||||
|
||||
### 3) How To Bring UP/Bring Down A Network Interface In Linux Using ip Command?
|
||||
|
||||
ip command is used to manage Network Interface Card (NIC). It’s replacement of old and deprecated ifconfig command on modern Linux systems.
|
||||
|
||||
It’s similar to ifconfig command but has many powerful features which isn’t available in ifconfig command.
|
||||
|
||||
Common Syntax for ip:
|
||||
|
||||
```
|
||||
# ip link set Down/Up
|
||||
```
|
||||
|
||||
Run the following command to bring down the `enp0s3` interface in Linux.
|
||||
|
||||
```
|
||||
# ip link set enp0s3 down
|
||||
```
|
||||
|
||||
Yes, the given interface is down now as per the following output.
|
||||
|
||||
```
|
||||
# ip a | grep -A 1 "enp0s3:"
|
||||
2: enp0s3: mtu 1500 qdisc fq_codel state DOWN group default qlen 1000
|
||||
link/ether 08:00:27:c2:e4:e8 brd ff:ff:ff:ff:ff:ff
|
||||
```
|
||||
|
||||
Run the following command to bring down the `enp0s3` interface in Linux.
|
||||
|
||||
```
|
||||
# ip link set enp0s3 up
|
||||
```
|
||||
|
||||
Yes, the given interface is up now as per the following output.
|
||||
|
||||
```
|
||||
# ip a | grep -A 5 "enp0s3:"
|
||||
2: enp0s3: mtu 1500 qdisc fq_codel state UP group default qlen 1000
|
||||
link/ether 08:00:27:c2:e4:e8 brd ff:ff:ff:ff:ff:ff
|
||||
inet 192.168.1.4/24 brd 192.168.1.255 scope global dynamic noprefixroute enp0s3
|
||||
valid_lft 86294sec preferred_lft 86294sec
|
||||
inet6 fe80::3899:270f:ae38:b433/64 scope link noprefixroute
|
||||
valid_lft forever preferred_lft forever
|
||||
```
|
||||
|
||||
### 4) How To Enable And Disable A Network Interface In Linux Using nmcli Command?
|
||||
|
||||
nmcli is a command-line tool for controlling NetworkManager and reporting network status.
|
||||
|
||||
It can be utilized as a replacement for nm-applet or other graphical clients. nmcli is used to create, display, edit, delete, activate, and deactivate network
|
||||
|
||||
connections, as well as control and display network device status.
|
||||
|
||||
Run the following command to identify the interface name because nmcli command is perform most of the task using `profile name` instead of `device name`.
|
||||
|
||||
```
|
||||
# nmcli con show
|
||||
NAME UUID TYPE DEVICE
|
||||
Wired connection 1 3d5afa0a-419a-3d1a-93e6-889ce9c6a18c ethernet enp0s3
|
||||
Wired connection 2 a22154b7-4cc4-3756-9d8d-da5a4318e146 ethernet enp0s8
|
||||
```
|
||||
|
||||
Common Syntax for ip:
|
||||
|
||||
```
|
||||
# nmcli con Down/Up
|
||||
```
|
||||
|
||||
Run the following command to bring down the `enp0s3` interface in Linux. You have to give `profile name` instead of `device name` to bring down it.
|
||||
|
||||
```
|
||||
# nmcli con down 'Wired connection 1'
|
||||
Connection 'Wired connection 1' successfully deactivated (D-Bus active path: /org/freedesktop/NetworkManager/ActiveConnection/6)
|
||||
```
|
||||
|
||||
Yes, the given interface is down now as per the following output.
|
||||
|
||||
```
|
||||
# nmcli dev status
|
||||
DEVICE TYPE STATE CONNECTION
|
||||
enp0s8 ethernet connected Wired connection 2
|
||||
enp0s3 ethernet disconnected --
|
||||
lo loopback unmanaged --
|
||||
```
|
||||
|
||||
Run the following command to bring down the `enp0s3` interface in Linux. You have to give `profile name` instead of `device name` to bring down it.
|
||||
|
||||
```
|
||||
# nmcli con up 'Wired connection 1'
|
||||
Connection successfully activated (D-Bus active path: /org/freedesktop/NetworkManager/ActiveConnection/7)
|
||||
```
|
||||
|
||||
Yes, the given interface is up now as per the following output.
|
||||
|
||||
```
|
||||
# nmcli dev status
|
||||
DEVICE TYPE STATE CONNECTION
|
||||
enp0s8 ethernet connected Wired connection 2
|
||||
enp0s3 ethernet connected Wired connection 1
|
||||
lo loopback unmanaged --
|
||||
```
|
||||
|
||||
### 5) How To Bring UP/Bring Down A Network Interface In Linux Using nmtui Command?
|
||||
|
||||
nmtui is a curses based TUI application for interacting with NetworkManager.
|
||||
|
||||
When starting nmtui, the user is prompted to choose the activity to perform unless it was specified as the first argument.
|
||||
|
||||
Run the following command launch the nmtui interface. Select “Active a connection” and hit “OK”
|
||||
|
||||
```
|
||||
# nmtui
|
||||
```
|
||||
|
||||
[![][1]![][1]][2]
|
||||
|
||||
Select the interface which you want to bring down then hit “Deactivate” button.
|
||||
[![][1]![][1]][3]
|
||||
|
||||
For activation do the same above procedure.
|
||||
[![][1]![][1]][4]
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.2daygeek.com/enable-disable-up-down-nic-network-interface-port-linux-using-ifconfig-ifdown-ifup-ip-nmcli-nmtui/
|
||||
|
||||
作者：[Magesh Maruthamuthu][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://www.2daygeek.com/author/magesh/
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7
|
||||
[2]: https://www.2daygeek.com/wp-content/uploads/2019/04/enable-disable-up-down-nic-network-interface-port-linux-nmtui-1.png
|
||||
[3]: https://www.2daygeek.com/wp-content/uploads/2019/04/enable-disable-up-down-nic-network-interface-port-linux-nmtui-2.png
|
||||
[4]: https://www.2daygeek.com/wp-content/uploads/2019/04/enable-disable-up-down-nic-network-interface-port-linux-nmtui-3.png
|
||||
@@ -0,0 +1,419 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (Inter-process communication in Linux: Shared storage)
|
||||
[#]: via: (https://opensource.com/article/19/4/interprocess-communication-linux-storage)
|
||||
[#]: author: (Marty Kalin https://opensource.com/users/mkalindepauledu)
|
||||
|
||||
Inter-process communication in Linux: Shared storage
|
||||
======
|
||||
Learn how processes synchronize with each other in Linux.
|
||||
![Filing papers and documents][1]
|
||||
|
||||
This is the first article in a series about [interprocess communication][2] (IPC) in Linux. The series uses code examples in C to clarify the following IPC mechanisms:
|
||||
|
||||
* Shared files
|
||||
* Shared memory (with semaphores)
|
||||
* Pipes (named and unnamed)
|
||||
* Message queues
|
||||
* Sockets
|
||||
* Signals
|
||||
|
||||
|
||||
|
||||
This article reviews some core concepts before moving on to the first two of these mechanisms: shared files and shared memory.
|
||||
|
||||
### Core concepts
|
||||
|
||||
A _process_ is a program in execution, and each process has its own address space, which comprises the memory locations that the process is allowed to access. A process has one or more _threads_ of execution, which are sequences of executable instructions: a _single-threaded_ process has just one thread, whereas a _multi-threaded_ process has more than one thread. Threads within a process share various resources, in particular, address space. Accordingly, threads within a process can communicate straightforwardly through shared memory, although some modern languages (e.g., Go) encourage a more disciplined approach such as the use of thread-safe channels. Of interest here is that different processes, by default, do _not_ share memory.
|
||||
|
||||
There are various ways to launch processes that then communicate, and two ways dominate in the examples that follow:
|
||||
|
||||
* A terminal is used to start one process, and perhaps a different terminal is used to start another.
|
||||
* The system function **fork** is called within one process (the parent) to spawn another process (the child).
|
||||
|
||||
|
||||
|
||||
The first examples take the terminal approach. The [code examples][3] are available in a ZIP file on my website.
|
||||
|
||||
### Shared files
|
||||
|
||||
Programmers are all too familiar with file access, including the many pitfalls (non-existent files, bad file permissions, and so on) that beset the use of files in programs. Nonetheless, shared files may be the most basic IPC mechanism. Consider the relatively simple case in which one process ( _producer_ ) creates and writes to a file, and another process ( _consumer_ ) reads from this same file:
|
||||
|
||||
|
||||
```
|
||||
writes +-----------+ reads
|
||||
producer-------->| disk file |<\-------consumer
|
||||
+-----------+
|
||||
```
|
||||
|
||||
The obvious challenge in using this IPC mechanism is that a _race condition_ might arise: the producer and the consumer might access the file at exactly the same time, thereby making the outcome indeterminate. To avoid a race condition, the file must be locked in a way that prevents a conflict between a _write_ operation and any another operation, whether a _read_ or a _write_. The locking API in the standard system library can be summarized as follows:
|
||||
|
||||
* A producer should gain an exclusive lock on the file before writing to the file. An _exclusive_ lock can be held by one process at most, which rules out a race condition because no other process can access the file until the lock is released.
|
||||
* A consumer should gain at least a shared lock on the file before reading from the file. Multiple _readers_ can hold a _shared_ lock at the same time, but no _writer_ can access a file when even a single _reader_ holds a shared lock.
|
||||
|
||||
|
||||
|
||||
A shared lock promotes efficiency. If one process is just reading a file and not changing its contents, there is no reason to prevent other processes from doing the same. Writing, however, clearly demands exclusive access to a file.
|
||||
|
||||
The standard I/O library includes a utility function named **fcntl** that can be used to inspect and manipulate both exclusive and shared locks on a file. The function works through a _file descriptor_ , a non-negative integer value that, within a process, identifies a file. (Different file descriptors in different processes may identify the same physical file.) For file locking, Linux provides the library function **flock** , which is a thin wrapper around **fcntl**. The first example uses the **fcntl** function to expose API details.
|
||||
|
||||
#### Example 1. The _producer_ program
|
||||
|
||||
|
||||
```
|
||||
#include <stdio.h>
|
||||
#include <stdlib.h>
|
||||
#include <fcntl.h>
|
||||
#include <unistd.h>
|
||||
#include <string.h>
|
||||
|
||||
#define FileName "data.dat"
|
||||
#define DataString "Now is the winter of our discontent\nMade glorious summer by this sun of York\n"
|
||||
|
||||
void report_and_exit(const char* msg) {
|
||||
[perror][4](msg);
|
||||
[exit][5](-1); /* EXIT_FAILURE */
|
||||
}
|
||||
|
||||
int main() {
|
||||
struct flock lock;
|
||||
lock.l_type = F_WRLCK; /* read/write (exclusive versus shared) lock */
|
||||
lock.l_whence = SEEK_SET; /* base for seek offsets */
|
||||
lock.l_start = 0; /* 1st byte in file */
|
||||
lock.l_len = 0; /* 0 here means 'until EOF' */
|
||||
lock.l_pid = getpid(); /* process id */
|
||||
|
||||
int fd; /* file descriptor to identify a file within a process */
|
||||
if ((fd = open(FileName, O_RDWR | O_CREAT, 0666)) < 0) /* -1 signals an error */
|
||||
report_and_exit("open failed...");
|
||||
|
||||
if (fcntl(fd, F_SETLK, &lock) < 0) /** F_SETLK doesn't block, F_SETLKW does **/
|
||||
report_and_exit("fcntl failed to get lock...");
|
||||
else {
|
||||
write(fd, DataString, [strlen][6](DataString)); /* populate data file */
|
||||
[fprintf][7](stderr, "Process %d has written to data file...\n", lock.l_pid);
|
||||
}
|
||||
|
||||
/* Now release the lock explicitly. */
|
||||
lock.l_type = F_UNLCK;
|
||||
if (fcntl(fd, F_SETLK, &lock) < 0)
|
||||
report_and_exit("explicit unlocking failed...");
|
||||
|
||||
close(fd); /* close the file: would unlock if needed */
|
||||
return 0; /* terminating the process would unlock as well */
|
||||
}
|
||||
```
|
||||
|
||||
The main steps in the _producer_ program above can be summarized as follows:
|
||||
|
||||
* The program declares a variable of type **struct flock** , which represents a lock, and initializes the structure's five fields. The first initialization: [code]`lock.l_type = F_WRLCK; /* exclusive lock */`[/code] makes the lock an exclusive ( _read-write_ ) rather than a shared ( _read-only_ ) lock. If the _producer_ gains the lock, then no other process will be able to write or read the file until the _producer_ releases the lock, either explicitly with the appropriate call to **fcntl** or implicitly by closing the file. (When the process terminates, any opened files would be closed automatically, thereby releasing the lock.)
|
||||
* The program then initializes the remaining fields. The chief effect is that the _entire_ file is to be locked. However, the locking API allows only designated bytes to be locked. For example, if the file contains multiple text records, then a single record (or even part of a record) could be locked and the rest left unlocked.
|
||||
* The first call to **fcntl** : [code]`if (fcntl(fd, F_SETLK, &lock) < 0)`[/code] tries to lock the file exclusively, checking whether the call succeeded. In general, the **fcntl** function returns **-1** (hence, less than zero) to indicate failure. The second argument **F_SETLK** means that the call to **fcntl** does _not_ block: the function returns immediately, either granting the lock or indicating failure. If the flag **F_SETLKW** (the **W** at the end is for _wait_ ) were used instead, the call to **fcntl** would block until gaining the lock was possible. In the calls to **fcntl** , the first argument **fd** is the file descriptor, the second argument specifies the action to be taken (in this case, **F_SETLK** for setting the lock), and the third argument is the address of the lock structure (in this case, **& lock**).
|
||||
* If the _producer_ gains the lock, the program writes two text records to the file.
|
||||
* After writing to the file, the _producer_ changes the lock structure's **l_type** field to the _unlock_ value: [code]`lock.l_type = F_UNLCK;`[/code] and calls **fcntl** to perform the unlocking operation. The program finishes up by closing the file and exiting.
|
||||
|
||||
|
||||
|
||||
#### Example 2. The _consumer_ program
|
||||
|
||||
|
||||
```
|
||||
#include <stdio.h>
|
||||
#include <stdlib.h>
|
||||
#include <fcntl.h>
|
||||
#include <unistd.h>
|
||||
|
||||
#define FileName "data.dat"
|
||||
|
||||
void report_and_exit(const char* msg) {
|
||||
[perror][4](msg);
|
||||
[exit][5](-1); /* EXIT_FAILURE */
|
||||
}
|
||||
|
||||
int main() {
|
||||
struct flock lock;
|
||||
lock.l_type = F_WRLCK; /* read/write (exclusive) lock */
|
||||
lock.l_whence = SEEK_SET; /* base for seek offsets */
|
||||
lock.l_start = 0; /* 1st byte in file */
|
||||
lock.l_len = 0; /* 0 here means 'until EOF' */
|
||||
lock.l_pid = getpid(); /* process id */
|
||||
|
||||
int fd; /* file descriptor to identify a file within a process */
|
||||
if ((fd = open(FileName, O_RDONLY)) < 0) /* -1 signals an error */
|
||||
report_and_exit("open to read failed...");
|
||||
|
||||
/* If the file is write-locked, we can't continue. */
|
||||
fcntl(fd, F_GETLK, &lock); /* sets lock.l_type to F_UNLCK if no write lock */
|
||||
if (lock.l_type != F_UNLCK)
|
||||
report_and_exit("file is still write locked...");
|
||||
|
||||
lock.l_type = F_RDLCK; /* prevents any writing during the reading */
|
||||
if (fcntl(fd, F_SETLK, &lock) < 0)
|
||||
report_and_exit("can't get a read-only lock...");
|
||||
|
||||
/* Read the bytes (they happen to be ASCII codes) one at a time. */
|
||||
int c; /* buffer for read bytes */
|
||||
while (read(fd, &c, 1) > 0) /* 0 signals EOF */
|
||||
write(STDOUT_FILENO, &c, 1); /* write one byte to the standard output */
|
||||
|
||||
/* Release the lock explicitly. */
|
||||
lock.l_type = F_UNLCK;
|
||||
if (fcntl(fd, F_SETLK, &lock) < 0)
|
||||
report_and_exit("explicit unlocking failed...");
|
||||
|
||||
close(fd);
|
||||
return 0;
|
||||
}
|
||||
```
|
||||
|
||||
The _consumer_ program is more complicated than necessary to highlight features of the locking API. In particular, the _consumer_ program first checks whether the file is exclusively locked and only then tries to gain a shared lock. The relevant code is:
|
||||
|
||||
|
||||
```
|
||||
lock.l_type = F_WRLCK;
|
||||
...
|
||||
fcntl(fd, F_GETLK, &lock); /* sets lock.l_type to F_UNLCK if no write lock */
|
||||
if (lock.l_type != F_UNLCK)
|
||||
report_and_exit("file is still write locked...");
|
||||
```
|
||||
|
||||
The **F_GETLK** operation specified in the **fcntl** call checks for a lock, in this case, an exclusive lock given as **F_WRLCK** in the first statement above. If the specified lock does not exist, then the **fcntl** call automatically changes the lock type field to **F_UNLCK** to indicate this fact. If the file is exclusively locked, the _consumer_ terminates. (A more robust version of the program might have the _consumer_ **sleep** a bit and try again several times.)
|
||||
|
||||
If the file is not currently locked, then the _consumer_ tries to gain a shared ( _read-only_ ) lock ( **F_RDLCK** ). To shorten the program, the **F_GETLK** call to **fcntl** could be dropped because the **F_RDLCK** call would fail if a _read-write_ lock already were held by some other process. Recall that a _read-only_ lock does prevent any other process from writing to the file, but allows other processes to read from the file. In short, a _shared_ lock can be held by multiple processes. After gaining a shared lock, the _consumer_ program reads the bytes one at a time from the file, prints the bytes to the standard output, releases the lock, closes the file, and terminates.
|
||||
|
||||
Here is the output from the two programs launched from the same terminal with **%** as the command line prompt:
|
||||
|
||||
|
||||
```
|
||||
% ./producer
|
||||
Process 29255 has written to data file...
|
||||
|
||||
% ./consumer
|
||||
Now is the winter of our discontent
|
||||
Made glorious summer by this sun of York
|
||||
```
|
||||
|
||||
In this first code example, the data shared through IPC is text: two lines from Shakespeare's play _Richard III_. Yet, the shared file's contents could be voluminous, arbitrary bytes (e.g., a digitized movie), which makes file sharing an impressively flexible IPC mechanism. The downside is that file access is relatively slow, whether the access involves reading or writing. As always, programming comes with tradeoffs. The next example has the upside of IPC through shared memory, rather than shared files, with a corresponding boost in performance.
|
||||
|
||||
### Shared memory
|
||||
|
||||
Linux systems provide two separate APIs for shared memory: the legacy System V API and the more recent POSIX one. These APIs should never be mixed in a single application, however. A downside of the POSIX approach is that features are still in development and dependent upon the installed kernel version, which impacts code portability. For example, the POSIX API, by default, implements shared memory as a _memory-mapped file_ : for a shared memory segment, the system maintains a _backing file_ with corresponding contents. Shared memory under POSIX can be configured without a backing file, but this may impact portability. My example uses the POSIX API with a backing file, which combines the benefits of memory access (speed) and file storage (persistence).
|
||||
|
||||
The shared-memory example has two programs, named _memwriter_ and _memreader_ , and uses a _semaphore_ to coordinate their access to the shared memory. Whenever shared memory comes into the picture with a _writer_ , whether in multi-processing or multi-threading, so does the risk of a memory-based race condition; hence, the semaphore is used to coordinate (synchronize) access to the shared memory.
|
||||
|
||||
The _memwriter_ program should be started first in its own terminal. The _memreader_ program then can be started (within a dozen seconds) in its own terminal. The output from the _memreader_ is:
|
||||
|
||||
|
||||
```
|
||||
`This is the way the world ends...`
|
||||
```
|
||||
|
||||
Each source file has documentation at the top explaining the link flags to be included during compilation.
|
||||
|
||||
Let's start with a review of how semaphores work as a synchronization mechanism. A general semaphore also is called a _counting semaphore_ , as it has a value (typically initialized to zero) that can be incremented. Consider a shop that rents bicycles, with a hundred of them in stock, with a program that clerks use to do the rentals. Every time a bike is rented, the semaphore is incremented by one; when a bike is returned, the semaphore is decremented by one. Rentals can continue until the value hits 100 but then must halt until at least one bike is returned, thereby decrementing the semaphore to 99.
|
||||
|
||||
A _binary semaphore_ is a special case requiring only two values: 0 and 1. In this situation, a semaphore acts as a _mutex_ : a mutual exclusion construct. The shared-memory example uses a semaphore as a mutex. When the semaphore's value is 0, the _memwriter_ alone can access the shared memory. After writing, this process increments the semaphore's value, thereby allowing the _memreader_ to read the shared memory.
|
||||
|
||||
#### Example 3. Source code for the _memwriter_ process
|
||||
|
||||
|
||||
```
|
||||
/** Compilation: gcc -o memwriter memwriter.c -lrt -lpthread **/
|
||||
#include <stdio.h>
|
||||
#include <stdlib.h>
|
||||
#include <sys/mman.h>
|
||||
#include <sys/stat.h>
|
||||
#include <fcntl.h>
|
||||
#include <unistd.h>
|
||||
#include <semaphore.h>
|
||||
#include <string.h>
|
||||
#include "shmem.h"
|
||||
|
||||
void report_and_exit(const char* msg) {
|
||||
[perror][4](msg);
|
||||
[exit][5](-1);
|
||||
}
|
||||
|
||||
int main() {
|
||||
int fd = shm_open(BackingFile, /* name from smem.h */
|
||||
O_RDWR | O_CREAT, /* read/write, create if needed */
|
||||
AccessPerms); /* access permissions (0644) */
|
||||
if (fd < 0) report_and_exit("Can't open shared mem segment...");
|
||||
|
||||
ftruncate(fd, ByteSize); /* get the bytes */
|
||||
|
||||
caddr_t memptr = mmap(NULL, /* let system pick where to put segment */
|
||||
ByteSize, /* how many bytes */
|
||||
PROT_READ | PROT_WRITE, /* access protections */
|
||||
MAP_SHARED, /* mapping visible to other processes */
|
||||
fd, /* file descriptor */
|
||||
0); /* offset: start at 1st byte */
|
||||
if ((caddr_t) -1 == memptr) report_and_exit("Can't get segment...");
|
||||
|
||||
[fprintf][7](stderr, "shared mem address: %p [0..%d]\n", memptr, ByteSize - 1);
|
||||
[fprintf][7](stderr, "backing file: /dev/shm%s\n", BackingFile );
|
||||
|
||||
/* semaphore code to lock the shared mem */
|
||||
sem_t* semptr = sem_open(SemaphoreName, /* name */
|
||||
O_CREAT, /* create the semaphore */
|
||||
AccessPerms, /* protection perms */
|
||||
0); /* initial value */
|
||||
if (semptr == (void*) -1) report_and_exit("sem_open");
|
||||
|
||||
[strcpy][8](memptr, MemContents); /* copy some ASCII bytes to the segment */
|
||||
|
||||
/* increment the semaphore so that memreader can read */
|
||||
if (sem_post(semptr) < 0) report_and_exit("sem_post");
|
||||
|
||||
sleep(12); /* give reader a chance */
|
||||
|
||||
/* clean up */
|
||||
munmap(memptr, ByteSize); /* unmap the storage */
|
||||
close(fd);
|
||||
sem_close(semptr);
|
||||
shm_unlink(BackingFile); /* unlink from the backing file */
|
||||
return 0;
|
||||
}
|
||||
```
|
||||
|
||||
Here's an overview of how the _memwriter_ and _memreader_ programs communicate through shared memory:
|
||||
|
||||
* The _memwriter_ program, shown above, calls the **shm_open** function to get a file descriptor for the backing file that the system coordinates with the shared memory. At this point, no memory has been allocated. The subsequent call to the misleadingly named function **ftruncate** : [code]`ftruncate(fd, ByteSize); /* get the bytes */`[/code] allocates **ByteSize** bytes, in this case, a modest 512 bytes. The _memwriter_ and _memreader_ programs access the shared memory only, not the backing file. The system is responsible for synchronizing the shared memory and the backing file.
|
||||
* The _memwriter_ then calls the **mmap** function: [code] caddr_t memptr = mmap(NULL, /* let system pick where to put segment */
|
||||
ByteSize, /* how many bytes */
|
||||
PROT_READ | PROT_WRITE, /* access protections */
|
||||
MAP_SHARED, /* mapping visible to other processes */
|
||||
fd, /* file descriptor */
|
||||
0); /* offset: start at 1st byte */ [/code] to get a pointer to the shared memory. (The _memreader_ makes a similar call.) The pointer type **caddr_t** starts with a **c** for **calloc** , a system function that initializes dynamically allocated storage to zeroes. The _memwriter_ uses the **memptr** for the later _write_ operation, using the library **strcpy** (string copy) function.
|
||||
* At this point, the _memwriter_ is ready for writing, but it first creates a semaphore to ensure exclusive access to the shared memory. A race condition would occur if the _memwriter_ were writing while the _memreader_ was reading. If the call to **sem_open** succeeds: [code] sem_t* semptr = sem_open(SemaphoreName, /* name */
|
||||
O_CREAT, /* create the semaphore */
|
||||
AccessPerms, /* protection perms */
|
||||
0); /* initial value */ [/code] then the writing can proceed. The **SemaphoreName** (any unique non-empty name will do) identifies the semaphore in both the _memwriter_ and the _memreader_. The initial value of zero gives the semaphore's creator, in this case, the _memwriter_ , the right to proceed, in this case, to the _write_ operation.
|
||||
* After writing, the _memwriter_ increments the semaphore value to 1: [code]`if (sem_post(semptr) < 0) ..`[/code] with a call to the **sem_post** function. Incrementing the semaphore releases the mutex lock and enables the _memreader_ to perform its _read_ operation. For good measure, the _memwriter_ also unmaps the shared memory from the _memwriter_ address space: [code]`munmap(memptr, ByteSize); /* unmap the storage *`[/code] This bars the _memwriter_ from further access to the shared memory.
|
||||
|
||||
|
||||
|
||||
#### Example 4. Source code for the _memreader_ process
|
||||
|
||||
|
||||
```
|
||||
/** Compilation: gcc -o memreader memreader.c -lrt -lpthread **/
|
||||
#include <stdio.h>
|
||||
#include <stdlib.h>
|
||||
#include <sys/mman.h>
|
||||
#include <sys/stat.h>
|
||||
#include <fcntl.h>
|
||||
#include <unistd.h>
|
||||
#include <semaphore.h>
|
||||
#include <string.h>
|
||||
#include "shmem.h"
|
||||
|
||||
void report_and_exit(const char* msg) {
|
||||
[perror][4](msg);
|
||||
[exit][5](-1);
|
||||
}
|
||||
|
||||
int main() {
|
||||
int fd = shm_open(BackingFile, O_RDWR, AccessPerms); /* empty to begin */
|
||||
if (fd < 0) report_and_exit("Can't get file descriptor...");
|
||||
|
||||
/* get a pointer to memory */
|
||||
caddr_t memptr = mmap(NULL, /* let system pick where to put segment */
|
||||
ByteSize, /* how many bytes */
|
||||
PROT_READ | PROT_WRITE, /* access protections */
|
||||
MAP_SHARED, /* mapping visible to other processes */
|
||||
fd, /* file descriptor */
|
||||
0); /* offset: start at 1st byte */
|
||||
if ((caddr_t) -1 == memptr) report_and_exit("Can't access segment...");
|
||||
|
||||
/* create a semaphore for mutual exclusion */
|
||||
sem_t* semptr = sem_open(SemaphoreName, /* name */
|
||||
O_CREAT, /* create the semaphore */
|
||||
AccessPerms, /* protection perms */
|
||||
0); /* initial value */
|
||||
if (semptr == (void*) -1) report_and_exit("sem_open");
|
||||
|
||||
/* use semaphore as a mutex (lock) by waiting for writer to increment it */
|
||||
if (!sem_wait(semptr)) { /* wait until semaphore != 0 */
|
||||
int i;
|
||||
for (i = 0; i < [strlen][6](MemContents); i++)
|
||||
write(STDOUT_FILENO, memptr + i, 1); /* one byte at a time */
|
||||
sem_post(semptr);
|
||||
}
|
||||
|
||||
/* cleanup */
|
||||
munmap(memptr, ByteSize);
|
||||
close(fd);
|
||||
sem_close(semptr);
|
||||
unlink(BackingFile);
|
||||
return 0;
|
||||
}
|
||||
```
|
||||
|
||||
In both the _memwriter_ and _memreader_ programs, the shared-memory functions of main interest are **shm_open** and **mmap** : on success, the first call returns a file descriptor for the backing file, which the second call then uses to get a pointer to the shared memory segment. The calls to **shm_open** are similar in the two programs except that the _memwriter_ program creates the shared memory, whereas the _memreader_ only accesses this already created memory:
|
||||
|
||||
|
||||
```
|
||||
int fd = shm_open(BackingFile, O_RDWR | O_CREAT, AccessPerms); /* memwriter */
|
||||
int fd = shm_open(BackingFile, O_RDWR, AccessPerms); /* memreader */
|
||||
```
|
||||
|
||||
With a file descriptor in hand, the calls to **mmap** are the same:
|
||||
|
||||
|
||||
```
|
||||
`caddr_t memptr = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);`
|
||||
```
|
||||
|
||||
The first argument to **mmap** is **NULL** , which means that the system determines where to allocate the memory in virtual address space. It's possible (but tricky) to specify an address instead. The **MAP_SHARED** flag indicates that the allocated memory is shareable among processes, and the last argument (in this case, zero) means that the offset for the shared memory should be the first byte. The **size** argument specifies the number of bytes to be allocated (in this case, 512), and the protection argument indicates that the shared memory can be written and read.
|
||||
|
||||
When the _memwriter_ program executes successfully, the system creates and maintains the backing file; on my system, the file is _/dev/shm/shMemEx_ , with _shMemEx_ as my name (given in the header file _shmem.h_ ) for the shared storage. In the current version of the _memwriter_ and _memreader_ programs, the statement:
|
||||
|
||||
|
||||
```
|
||||
`shm_unlink(BackingFile); /* removes backing file */`
|
||||
```
|
||||
|
||||
removes the backing file. If the **unlink** statement is omitted, then the backing file persists after the program terminates.
|
||||
|
||||
The _memreader_ , like the _memwriter_ , accesses the semaphore through its name in a call to **sem_open**. But the _memreader_ then goes into a wait state until the _memwriter_ increments the semaphore, whose initial value is 0:
|
||||
|
||||
|
||||
```
|
||||
`if (!sem_wait(semptr)) { /* wait until semaphore != 0 */`
|
||||
```
|
||||
|
||||
Once the wait is over, the _memreader_ reads the ASCII bytes from the shared memory, cleans up, and terminates.
|
||||
|
||||
The shared-memory API includes operations explicitly to synchronize the shared memory segment and the backing file. These operations have been omitted from the example to reduce clutter and keep the focus on the memory-sharing and semaphore code.
|
||||
|
||||
The _memwriter_ and _memreader_ programs are likely to execute without inducing a race condition even if the semaphore code is removed: the _memwriter_ creates the shared memory segment and writes immediately to it; the _memreader_ cannot even access the shared memory until this has been created. However, best practice requires that shared-memory access is synchronized whenever a _write_ operation is in the mix, and the semaphore API is important enough to be highlighted in a code example.
|
||||
|
||||
### Wrapping up
|
||||
|
||||
The shared-file and shared-memory examples show how processes can communicate through _shared storage_ , files in one case and memory segments in the other. The APIs for both approaches are relatively straightforward. Do these approaches have a common downside? Modern applications often deal with streaming data, indeed, with massively large streams of data. Neither the shared-file nor the shared-memory approaches are well suited for massive data streams. Channels of one type or another are better suited. Part 2 thus introduces channels and message queues, again with code examples in C.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/19/4/interprocess-communication-linux-storage
|
||||
|
||||
作者：[Marty Kalin][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://opensource.com/users/mkalindepauledu
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/documents_papers_file_storage_work.png?itok=YlXpAqAJ (Filing papers and documents)
|
||||
[2]: https://en.wikipedia.org/wiki/Inter-process_communication
|
||||
[3]: http://condor.depaul.edu/mkalin
|
||||
[4]: http://www.opengroup.org/onlinepubs/009695399/functions/perror.html
|
||||
[5]: http://www.opengroup.org/onlinepubs/009695399/functions/exit.html
|
||||
[6]: http://www.opengroup.org/onlinepubs/009695399/functions/strlen.html
|
||||
[7]: http://www.opengroup.org/onlinepubs/009695399/functions/fprintf.html
|
||||
[8]: http://www.opengroup.org/onlinepubs/009695399/functions/strcpy.html
|
||||
211
sources/tech/20190415 Kubernetes on Fedora IoT with k3s.md
Normal file
211
sources/tech/20190415 Kubernetes on Fedora IoT with k3s.md
Normal file
@@ -0,0 +1,211 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (Kubernetes on Fedora IoT with k3s)
|
||||
[#]: via: (https://fedoramagazine.org/kubernetes-on-fedora-iot-with-k3s/)
|
||||
[#]: author: (Lennart Jern https://fedoramagazine.org/author/lennartj/)
|
||||
|
||||
Kubernetes on Fedora IoT with k3s
|
||||
======
|
||||
|
||||
![][1]
|
||||
|
||||
Fedora IoT is an upcoming Fedora edition targeted at the Internet of Things. It was introduced last year on Fedora Magazine in the article [How to turn on an LED with Fedora IoT][2]. Since then, it has continued to improve together with Fedora Silverblue to provide an immutable base operating system aimed at container-focused workflows.
|
||||
|
||||
Kubernetes is an immensely popular container orchestration system. It is perhaps most commonly used on powerful hardware handling huge workloads. However, it can also be used on lightweight devices such as the Raspberry Pi 3. Read on to find out how.
|
||||
|
||||
### Why Kubernetes?
|
||||
|
||||
While Kubernetes is all the rage in the cloud, it may not be immediately obvious to run it on a small single board computer. But there are certainly reasons for doing it. First of all it is a great way to learn and get familiar with Kubernetes without the need for expensive hardware. Second, because of its popularity, there are [tons of applications][3] that comes pre-packaged for running in Kubernetes clusters. Not to mention the large community to provide help if you ever get stuck.
|
||||
|
||||
Last but not least, container orchestration may actually make things easier, even at the small scale in a home lab. This may not be apparent when tackling the the learning curve, but these skills will help when dealing with any cluster in the future. It doesn’t matter if it’s a single node Raspberry Pi cluster or a large scale machine learning farm.
|
||||
|
||||
#### K3s – a lightweight Kubernetes
|
||||
|
||||
A “normal” installation of Kubernetes (if such a thing can be said to exist) is a bit on the heavy side for IoT. The recommendation is a minimum of 2 GB RAM per machine! However, there are plenty of alternatives, and one of the newcomers is [k3s][4] – a lightweight Kubernetes distribution.
|
||||
|
||||
K3s is quite special in that it has replaced etcd with SQLite for its key-value storage needs. Another thing to note is that k3s ships as a single binary instead of one per component. This diminishes the memory footprint and simplifies the installation. Thanks to the above, k3s should be able to run k3s with just 512 MB of RAM, perfect for a small single board computer!
|
||||
|
||||
### What you will need
|
||||
|
||||
1. Fedora IoT in a virtual machine or on a physical device. See the excellent getting started guide [here][5]. One machine is enough but two will allow you to test adding more nodes to the cluster.
|
||||
2. [Configure the firewall][6] to allow traffic on ports 6443 and 8472. Or simply disable it for this experiment by running “systemctl stop firewalld”.
|
||||
|
||||
|
||||
|
||||
### Install k3s
|
||||
|
||||
Installing k3s is very easy. Simply run the installation script:
|
||||
|
||||
```
|
||||
curl -sfL https://get.k3s.io | sh -
|
||||
```
|
||||
|
||||
This will download, install and start up k3s. After installation, get a list of nodes from the server by running the following command:
|
||||
|
||||
```
|
||||
kubectl get nodes
|
||||
```
|
||||
|
||||
Note that there are several options that can be passed to the installation script through environment variables. These can be found in the [documentation][7]. And of course, there is nothing stopping you from installing k3s manually by downloading the binary directly.
|
||||
|
||||
While great for experimenting and learning, a single node cluster is not much of a cluster. Luckily, adding another node is no harder than setting up the first one. Just pass two environment variables to the installation script to make it find the first node and avoid running the server part of k3s
|
||||
|
||||
```
|
||||
curl -sfL https://get.k3s.io | K3S_URL=https://example-url:6443 \
|
||||
K3S_TOKEN=XXX sh -
|
||||
```
|
||||
|
||||
The example-url above should be replaced by the IP address or fully qualified domain name of the first node. On that node the token (represented by XXX) is found in the file /var/lib/rancher/k3s/server/node-token.
|
||||
|
||||
### Deploy some containers
|
||||
|
||||
Now that we have a Kubernetes cluster, what can we actually do with it? Let’s start by deploying a simple web server.
|
||||
|
||||
```
|
||||
kubectl create deployment my-server --image nginx
|
||||
```
|
||||
|
||||
This will create a [Deployment][8] named “my-server” from the container image “nginx” (defaulting to docker hub as registry and the latest tag). You can see the Pod created by running the following command.
|
||||
|
||||
```
|
||||
kubectl get pods
|
||||
```
|
||||
|
||||
In order to access the nginx server running in the pod, first expose the Deployment through a [Service][9]. The following command will create a Service with the same name as the deployment.
|
||||
|
||||
```
|
||||
kubectl expose deployment my-server --port 80
|
||||
```
|
||||
|
||||
The Service works as a kind of load balancer and DNS record for the Pods. For instance, when running a second Pod, we will be able to _curl_ the nginx server just by specifying _my-server_ (the name of the Service). See the example below for how to do this.
|
||||
|
||||
```
|
||||
# Start a pod and run bash interactively in it
|
||||
kubectl run debug --generator=run-pod/v1 --image=fedora -it -- bash
|
||||
# Wait for the bash prompt to appear
|
||||
curl my-server
|
||||
# You should get the "Welcome to nginx!" page as output
|
||||
```
|
||||
|
||||
### Ingress controller and external IP
|
||||
|
||||
By default, a Service only get a ClusterIP (only accessible inside the cluster), but you can also request an external IP for the service by setting its type to [LoadBalancer][10]. However, not all applications require their own IP address. Instead, it is often possible to share one IP address among many services by routing requests based on the host header or path. You can accomplish this in Kubernetes with an [Ingress][11], and this is what we will do. Ingresses also provide additional features such as TLS encryption of the traffic without having to modify your application.
|
||||
|
||||
Kubernetes needs an ingress controller to make the Ingress resources work and k3s includes [Traefik][12] for this purpose. It also includes a simple service load balancer that makes it possible to get an external IP for a Service in the cluster. The [documentation][13] describes the service like this:
|
||||
|
||||
> k3s includes a basic service load balancer that uses available host ports. If you try to create a load balancer that listens on port 80, for example, it will try to find a free host in the cluster for port 80. If no port is available the load balancer will stay in Pending.
|
||||
>
|
||||
> k3s README
|
||||
|
||||
The ingress controller is already exposed with this load balancer service. You can find the IP address that it is using with the following command.
|
||||
|
||||
```
|
||||
$ kubectl get svc --all-namespaces
|
||||
NAMESPACE NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
|
||||
default kubernetes ClusterIP 10.43.0.1 443/TCP 33d
|
||||
default my-server ClusterIP 10.43.174.38 80/TCP 30m
|
||||
kube-system kube-dns ClusterIP 10.43.0.10 53/UDP,53/TCP,9153/TCP 33d
|
||||
kube-system traefik LoadBalancer 10.43.145.104 10.0.0.8 80:31596/TCP,443:31539/TCP 33d
|
||||
```
|
||||
|
||||
Look for the Service named traefik. In the above example the IP we are interested in is 10.0.0.8.
|
||||
|
||||
### Route incoming requests
|
||||
|
||||
Let’s create an Ingress that routes requests to our web server based on the host header. This example uses [xip.io][14] to avoid having to set up DNS records. It works by including the IP adress as a subdomain, to use any subdomain of 10.0.0.8.xip.io to reach the IP 10.0.0.8. In other words, my-server.10.0.0.8.xip.io is used to reach the ingress controller in the cluster. You can try this right now (with your own IP instead of 10.0.0.8). Without an ingress in place you should reach the “default backend” which is just a page showing “404 page not found”.
|
||||
|
||||
We can tell the ingress controller to route requests to our web server Service with the following Ingress.
|
||||
|
||||
```
|
||||
apiVersion: extensions/v1beta1
|
||||
kind: Ingress
|
||||
metadata:
|
||||
name: my-server
|
||||
spec:
|
||||
rules:
|
||||
- host: my-server.10.0.0.8.xip.io
|
||||
http:
|
||||
paths:
|
||||
- path: /
|
||||
backend:
|
||||
serviceName: my-server
|
||||
servicePort: 80
|
||||
```
|
||||
|
||||
Save the above snippet in a file named _my-ingress.yaml_ and add it to the cluster by running this command:
|
||||
|
||||
```
|
||||
kubectl apply -f my-ingress.yaml
|
||||
```
|
||||
|
||||
You should now be able to reach the default nginx welcoming page on the fully qualified domain name you chose. In my example this would be my-server.10.0.0.8.xip.io. The ingress controller is routing the requests based on the information in the Ingress. A request to my-server.10.0.0.8.xip.io will be routed to the Service and port defined as backend in the Ingress (my-server and 80 in this case).
|
||||
|
||||
### What about IoT then?
|
||||
|
||||
Imagine the following scenario. You have dozens of devices spread out around your home or farm. It is a heterogeneous collection of IoT devices with various hardware capabilities, sensors and actuators. Maybe some of them have cameras, weather or light sensors. Others may be hooked up to control the ventilation, lights, blinds or blink LEDs.
|
||||
|
||||
In this scenario, you want to gather data from all the sensors, maybe process and analyze it before you finally use it to make decisions and control the actuators. In addition to this, you may want to visualize what’s going on by setting up a dashboard. So how can Kubernetes help us manage something like this? How can we make sure that Pods run on suitable devices?
|
||||
|
||||
The simple answer is labels. You can label the nodes according to capabilities, like this:
|
||||
|
||||
```
|
||||
kubectl label nodes <node-name> <label-key>=<label-value>
|
||||
# Example
|
||||
kubectl label nodes node2 camera=available
|
||||
```
|
||||
|
||||
Once they are labeled, it is easy to select suitable nodes for your workload with [nodeSelectors][15]. The final piece to the puzzle, if you want to run your Pods on _all_ suitable nodes is to use [DaemonSets][16] instead of Deployments. In other words, create one DaemonSet for each data collecting application that uses some unique sensor and use nodeSelectors to make sure they only run on nodes with the proper hardware.
|
||||
|
||||
The service discovery feature that allows Pods to find each other simply by Service name makes it quite easy to handle these kinds of distributed systems. You don’t need to know or configure IP addresses or custom ports for the applications. Instead, they can easily find each other through named Services in the cluster.
|
||||
|
||||
#### Utilize spare resources
|
||||
|
||||
With the cluster up and running, collecting data and controlling your lights and climate control you may feel that you are finished. However, there are still plenty of compute resources in the cluster that could be used for other projects. This is where Kubernetes really shines.
|
||||
|
||||
You shouldn’t have to worry about where exactly those resources are or calculate if there is enough memory to fit an extra application here or there. This is exactly what orchestration solves! You can easily deploy more applications in the cluster and let Kubernetes figure out where (or if) they will fit.
|
||||
|
||||
Why not run your own [NextCloud][17] instance? Or maybe [gitea][18]? You could also set up a CI/CD pipeline for all those IoT containers. After all, why would you build and cross compile them on your main computer if you can do it natively in the cluster?
|
||||
|
||||
The point here is that Kubernetes makes it easier to make use of the “hidden” resources that you often end up with otherwise. Kubernetes handles scheduling of Pods in the cluster based on available resources and fault tolerance so that you don’t have to. However, in order to help Kubernetes make reasonable decisions you should definitely add [resource requests][19] to your workloads.
|
||||
|
||||
### Summary
|
||||
|
||||
While Kubernetes, or container orchestration in general, may not usually be associated with IoT, it certainly makes a lot of sense to have an orchestrator when you are dealing with distributed systems. Not only does is allow you to handle a diverse and heterogeneous fleet of devices in a unified way, but it also simplifies communication between them. In addition, Kubernetes makes it easier to utilize spare resources.
|
||||
|
||||
Container technology made it possible to build applications that could “run anywhere”. Now Kubernetes makes it easier to manage the “anywhere” part. And as an immutable base to build it all on, we have Fedora IoT.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://fedoramagazine.org/kubernetes-on-fedora-iot-with-k3s/
|
||||
|
||||
作者：[Lennart Jern][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://fedoramagazine.org/author/lennartj/
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://fedoramagazine.org/wp-content/uploads/2019/04/k3s-1-816x345.png
|
||||
[2]: https://fedoramagazine.org/turnon-led-fedora-iot/
|
||||
[3]: https://hub.helm.sh/
|
||||
[4]: https://k3s.io
|
||||
[5]: https://docs.fedoraproject.org/en-US/iot/getting-started/
|
||||
[6]: https://github.com/rancher/k3s#open-ports--network-security
|
||||
[7]: https://github.com/rancher/k3s#systemd
|
||||
[8]: https://kubernetes.io/docs/concepts/workloads/controllers/deployment/
|
||||
[9]: https://kubernetes.io/docs/concepts/services-networking/service/
|
||||
[10]: https://kubernetes.io/docs/concepts/services-networking/service/#loadbalancer
|
||||
[11]: https://kubernetes.io/docs/concepts/services-networking/ingress/
|
||||
[12]: https://traefik.io/
|
||||
[13]: https://github.com/rancher/k3s/blob/master/README.md#service-load-balancer
|
||||
[14]: http://xip.io/
|
||||
[15]: https://kubernetes.io/docs/concepts/configuration/assign-pod-node/
|
||||
[16]: https://kubernetes.io/docs/concepts/workloads/controllers/daemonset/
|
||||
[17]: https://nextcloud.com/
|
||||
[18]: https://gitea.io/en-us/
|
||||
[19]: https://kubernetes.io/docs/concepts/configuration/manage-compute-resources-container/
|
||||
39
sources/tech/20190415 Troubleshooting slow WiFi on Linux.md
Normal file
39
sources/tech/20190415 Troubleshooting slow WiFi on Linux.md
Normal file
@@ -0,0 +1,39 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: (geekpi)
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (Troubleshooting slow WiFi on Linux)
|
||||
[#]: via: (https://www.linux.com/blog/troubleshooting-slow-wifi-linux)
|
||||
[#]: author: (OpenSource.com https://www.linux.com/USERS/OPENSOURCECOM)
|
||||
|
||||
Troubleshooting slow WiFi on Linux
|
||||
======
|
||||
|
||||
I'm no stranger to diagnosing hardware problems on [Linux systems][1]. Even though most of my professional work over the past few years has involved virtualization, I still enjoy crouching under desks and fumbling around with devices and memory modules. Well, except for the "crouching under desks" part. But none of that means that persistent and mysterious bugs aren't frustrating. I recently faced off against one of those bugs on my Ubuntu 18.04 workstation, which remained unsolved for months.
|
||||
|
||||
Here, I'll share my problem and my many attempts to resolve it. Even though you'll probably never encounter my specific issue, the troubleshooting process might be helpful. And besides, you'll get to enjoy feeling smug at how much time and effort I wasted following useless leads.
|
||||
|
||||
Read more at: [OpenSource.com][2]
|
||||
|
||||
I'm no stranger to diagnosing hardware problems on [Linux systems][1]. Even though most of my professional work over the past few years has involved virtualization, I still enjoy crouching under desks and fumbling around with devices and memory modules. Well, except for the "crouching under desks" part. But none of that means that persistent and mysterious bugs aren't frustrating. I recently faced off against one of those bugs on my Ubuntu 18.04 workstation, which remained unsolved for months.
|
||||
|
||||
Here, I'll share my problem and my many attempts to resolve it. Even though you'll probably never encounter my specific issue, the troubleshooting process might be helpful. And besides, you'll get to enjoy feeling smug at how much time and effort I wasted following useless leads.
|
||||
|
||||
Read more at: [OpenSource.com][2]
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.linux.com/blog/troubleshooting-slow-wifi-linux
|
||||
|
||||
作者：[OpenSource.com][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://www.linux.com/USERS/OPENSOURCECOM
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://www.manning.com/books/linux-in-action?a_aid=bootstrap-it&a_bid=4ca15fc9&chan=opensource
|
||||
[2]: https://opensource.com/article/19/4/troubleshooting-wifi-linux
|
||||
@@ -0,0 +1,263 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (Building a DNS-as-a-service with OpenStack Designate)
|
||||
[#]: via: (https://opensource.com/article/19/4/getting-started-openstack-designate)
|
||||
[#]: author: (Amjad Yaseen https://opensource.com/users/ayaseen)
|
||||
|
||||
Building a DNS-as-a-service with OpenStack Designate
|
||||
======
|
||||
Learn how to install and configure Designate, a multi-tenant
|
||||
DNS-as-a-service (DNSaaS) for OpenStack.
|
||||
![Command line prompt][1]
|
||||
|
||||
[Designate][2] is a multi-tenant DNS-as-a-service that includes a REST API for domain and record management, a framework for integration with [Neutron][3], and integration support for Bind9.
|
||||
|
||||
You would want to consider a DNSaaS for the following:
|
||||
|
||||
* A clean REST API for managing zones and records
|
||||
* Automatic records generated (with OpenStack integration)
|
||||
* Support for multiple authoritative name servers
|
||||
* Hosting multiple projects/organizations
|
||||
|
||||
|
||||
|
||||
![Designate's architecture][4]
|
||||
|
||||
This article explains how to manually install and configure the latest release of Designate service on CentOS or Red Hat Enterprise Linux 7 (RHEL 7), but you can use the same configuration on other distributions.
|
||||
|
||||
### Install Designate on OpenStack
|
||||
|
||||
I have Ansible roles for bind and Designate that demonstrate the setup in my [GitHub repository][5].
|
||||
|
||||
This setup presumes bind service is external (even though you can install bind locally) on the OpenStack controller node.
|
||||
|
||||
1. Install Designate's packages and bind (on OpenStack controller): [code]`# yum install openstack-designate-* bind bind-utils -y`
|
||||
```
|
||||
2. Create the Designate database and user: [code] MariaDB [(none)]> CREATE DATABASE designate CHARACTER SET utf8 COLLATE utf8_general_ci;
|
||||
|
||||
MariaDB [(none)]> GRANT ALL PRIVILEGES ON designate.* TO \
|
||||
'designate'@'localhost' IDENTIFIED BY 'rhlab123';
|
||||
|
||||
MariaDB [(none)]> GRANT ALL PRIVILEGES ON designate.* TO 'designate'@'%' \
|
||||
IDENTIFIED BY 'rhlab123';
|
||||
```
|
||||
|
||||
|
||||
|
||||
|
||||
Note: Bind packages must be installed on the controller side for Remote Name Daemon Control (RNDC) to function properly.
|
||||
|
||||
### Configure bind (DNS server)
|
||||
|
||||
1. Generate RNDC files: [code] rndc-confgen -a -k designate -c /etc/rndc.key -r /dev/urandom
|
||||
|
||||
cat <<EOF> etcrndc.conf
|
||||
include "/etc/rndc.key";
|
||||
options {
|
||||
default-key "designate";
|
||||
default-server {{ DNS_SERVER_IP }};
|
||||
default-port 953;
|
||||
};
|
||||
EOF
|
||||
```
|
||||
2. Add the following into **named.conf** : [code]`include "/etc/rndc.key"; controls { inet {{ DNS_SERVER_IP }} allow { localhost;{{ CONTROLLER_SERVER_IP }}; } keys { "designate"; }; };`[/code] In the **option** section, add: [code] options {
|
||||
...
|
||||
allow-new-zones yes;
|
||||
request-ixfr no;
|
||||
listen-on port 53 { any; };
|
||||
recursion no;
|
||||
allow-query { 127.0.0.1; {{ CONTROLLER_SERVER_IP }}; };
|
||||
}; [/code] Add the right permissions: [code] chown named:named /etc/rndc.key
|
||||
chown named:named /etc/rndc.conf
|
||||
chmod 600 /etc/rndc.key
|
||||
chown -v root:named /etc/named.conf
|
||||
chmod g+w /var/named
|
||||
|
||||
# systemctl restart named
|
||||
# setsebool named_write_master_zones 1
|
||||
```
|
||||
|
||||
3. Push **rndc.key** and **rndc.conf** into the OpenStack controller: [code]`# scp -r /etc/rndc* {{ CONTROLLER_SERVER_IP }}:/etc/`
|
||||
```
|
||||
## Create OpenStack Designate service and endpoints
|
||||
|
||||
Enter:
|
||||
```
|
||||
|
||||
|
||||
# openstack user create --domain default --password-prompt designate
|
||||
# openstack role add --project services --user designate admin
|
||||
# openstack service create --name designate --description "DNS" dns
|
||||
|
||||
# openstack endpoint create --region RegionOne dns public http://{{ CONTROLLER_SERVER_IP }}:9001/
|
||||
# openstack endpoint create --region RegionOne dns internal http://{{ CONTROLLER_SERVER_IP }}:9001/
|
||||
# openstack endpoint create --region RegionOne dns admin http://{{ CONTROLLER_SERVER_IP }}:9001/
|
||||
|
||||
```
|
||||
## Configure Designate service
|
||||
|
||||
1. Edit **/etc/designate/designate.conf** :
|
||||
* In the **[service:api]** section, configure **auth_strategy** : [code] [service:api]
|
||||
listen = 0.0.0.0:9001
|
||||
auth_strategy = keystone
|
||||
api_base_uri = http://{{ CONTROLLER_SERVER_IP }}:9001/
|
||||
enable_api_v2 = True
|
||||
enabled_extensions_v2 = quotas, reports
|
||||
```
|
||||
* In the **[keystone_authtoken]** section, configure the following options: [code] [keystone_authtoken]
|
||||
auth_type = password
|
||||
username = designate
|
||||
password = rhlab123
|
||||
project_name = service
|
||||
project_domain_name = Default
|
||||
user_domain_name = Default
|
||||
www_authenticate_uri = http://{{ CONTROLLER_SERVER_IP }}:5000/
|
||||
auth_url = http://{{ CONTROLLER_SERVER_IP }}:5000/
|
||||
```
|
||||
* In the **[service:worker]** section, enable the worker model: [code] enabled = True
|
||||
notify = True
|
||||
```
|
||||
* In the **[storage:sqlalchemy]** section, configure database access: [code] [storage:sqlalchemy]
|
||||
connection = mysql+pymysql://designate:rhlab123@{{ CONTROLLER_SERVER_IP }}/designate
|
||||
```
|
||||
* Populate the Designate database: [code]`# su -s /bin/sh -c "designate-manage database sync" designate`
|
||||
```
|
||||
|
||||
|
||||
2. Create Designate's **pools.yaml** file (has target and bind details):
|
||||
* Edit **/etc/designate/pools.yaml** : [code] - name: default
|
||||
# The name is immutable. There will be no option to change the name after
|
||||
# creation and the only way will to change it will be to delete it
|
||||
# (and all zones associated with it) and recreate it.
|
||||
description: Default Pool
|
||||
|
||||
attributes: {}
|
||||
|
||||
# List out the NS records for zones hosted within this pool
|
||||
# This should be a record that is created outside of designate, that
|
||||
# points to the public IP of the controller node.
|
||||
ns_records:
|
||||
\- hostname: {{Controller_FQDN}}. # Thisis mDNS
|
||||
priority: 1
|
||||
|
||||
# List out the nameservers for this pool. These are the actual BIND servers.
|
||||
# We use these to verify changes have propagated to all nameservers.
|
||||
nameservers:
|
||||
\- host: {{ DNS_SERVER_IP }}
|
||||
port: 53
|
||||
|
||||
# List out the targets for this pool. For BIND there will be one
|
||||
# entry for each BIND server, as we have to run rndc command on each server
|
||||
targets:
|
||||
\- type: bind9
|
||||
description: BIND9 Server 1
|
||||
|
||||
# List out the designate-mdns servers from which BIND servers should
|
||||
# request zone transfers (AXFRs) from.
|
||||
# This should be the IP of the controller node.
|
||||
# If you have multiple controllers you can add multiple masters
|
||||
# by running designate-mdns on them, and adding them here.
|
||||
masters:
|
||||
\- host: {{ CONTROLLER_SERVER_IP }}
|
||||
port: 5354
|
||||
|
||||
# BIND Configuration options
|
||||
options:
|
||||
host: {{ DNS_SERVER_IP }}
|
||||
port: 53
|
||||
rndc_host: {{ DNS_SERVER_IP }}
|
||||
rndc_port: 953
|
||||
rndc_key_file: /etc/rndc.key
|
||||
rndc_config_file: /etc/rndc.conf
|
||||
```
|
||||
* Populate Designate's pools: [code]`su -s /bin/sh -c "designate-manage pool update" designate`
|
||||
```
|
||||
|
||||
|
||||
|
||||
3. Start Designate central and API services: [code]`systemctl enable --now designate-central designate-api`
|
||||
```
|
||||
4. Verify Designate's services are up: [code] # openstack dns service list
|
||||
|
||||
+--------------+--------+-------+--------------+
|
||||
| service_name | status | stats | capabilities |
|
||||
+--------------+--------+-------+--------------+
|
||||
| central | UP | - | - |
|
||||
| api | UP | - | - |
|
||||
| mdns | UP | - | - |
|
||||
| worker | UP | - | - |
|
||||
| producer | UP | - | - |
|
||||
+--------------+--------+-------+--------------+
|
||||
```
|
||||
|
||||
|
||||
|
||||
|
||||
### Configure OpenStack Neutron with external DNS
|
||||
|
||||
1. Configure iptables for Designate services: [code] # iptables -I INPUT -p tcp -m multiport --dports 9001 -m comment --comment "designate incoming" -j ACCEPT
|
||||
|
||||
# iptables -I INPUT -p tcp -m multiport --dports 5354 -m comment --comment "Designate mdns incoming" -j ACCEPT
|
||||
|
||||
# iptables -I INPUT -p tcp -m multiport --dports 53 -m comment --comment "bind incoming" -j ACCEPT
|
||||
|
||||
|
||||
# iptables -I INPUT -p udp -m multiport --dports 53 -m comment --comment "bind/powerdns incoming" -j ACCEPT
|
||||
|
||||
# iptables -I INPUT -p tcp -m multiport --dports 953 -m comment --comment "rndc incoming - bind only" -j ACCEPT
|
||||
|
||||
# service iptables save; service iptables restart
|
||||
# setsebool named_write_master_zones 1
|
||||
```
|
||||
2. Edit the **[default]** section of **/etc/neutron/neutron.conf** : [code]`external_dns_driver = designate`
|
||||
```
|
||||
|
||||
3. Add the **[designate]** section in **/_etc/_neutron/neutron.conf** : [code] [designate]
|
||||
url = http://{{ CONTROLLER_SERVER_IP }}:9001/v2 ## This end point of designate
|
||||
auth_type = password
|
||||
auth_url = http://{{ CONTROLLER_SERVER_IP }}:5000
|
||||
username = designate
|
||||
password = rhlab123
|
||||
project_name = services
|
||||
project_domain_name = Default
|
||||
user_domain_name = Default
|
||||
allow_reverse_dns_lookup = True
|
||||
ipv4_ptr_zone_prefix_size = 24
|
||||
ipv6_ptr_zone_prefix_size = 116
|
||||
```
|
||||
4. Edit **dns_domain** in **neutron.conf** : [code] dns_domain = rhlab.dev.
|
||||
|
||||
# systemctl restart neutron-*
|
||||
```
|
||||
|
||||
5. Add **dns** to the list of Modular Layer 2 (ML2) drivers in **/etc/neutron/plugins/ml2/ml2_conf.ini** : [code]`extension_drivers=port_security,qos,dns`
|
||||
```
|
||||
6. Add **zone** in Designate: [code]`# openstack zone create –email=admin@rhlab.dev rhlab.dev.`[/code] Add a new record in **zone rhlab.dev** : [code]`# openstack recordset create --record '192.168.1.230' --type A rhlab.dev. Test`
|
||||
```
|
||||
|
||||
|
||||
|
||||
|
||||
Designate should now be installed and configured.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/19/4/getting-started-openstack-designate
|
||||
|
||||
作者：[Amjad Yaseen][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://opensource.com/users/ayaseen
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/command_line_prompt.png?itok=wbGiJ_yg (Command line prompt)
|
||||
[2]: https://docs.openstack.org/designate/latest/
|
||||
[3]: /article/19/3/openstack-neutron
|
||||
[4]: https://opensource.com/sites/default/files/uploads/openstack_designate_architecture.png (Designate's architecture)
|
||||
[5]: https://github.com/ayaseen/designate
|
||||
79
sources/tech/20190416 Can schools be agile.md
Normal file
79
sources/tech/20190416 Can schools be agile.md
Normal file
@@ -0,0 +1,79 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (Can schools be agile?)
|
||||
[#]: via: (https://opensource.com/open-organization/19/4/education-culture-agile)
|
||||
[#]: author: (Ben Owens https://opensource.com/users/engineerteacher/users/ke4qqq/users/n8chz/users/don-watkins)
|
||||
|
||||
Can schools be agile?
|
||||
======
|
||||
We certainly don't need to run our schools like businesses—but we could
|
||||
benefit from educational organizations more focused on continuous
|
||||
improvement.
|
||||
![][1]
|
||||
|
||||
We've all had those _deja vu_ moments that make us think "I've seen this before!" I experienced them often in the late 1980s, when I first began my career in industry. I was caught up in a wave of organizational change, where the U.S. manufacturing sector was experimenting with various models that asked leaders, managers, and engineers like me to rethink how we approached things like quality, cost, innovation, and shareholder value. It seems as if every year (sometimes, more frequently) we'd study yet another book to identify the "best practices" necessary for making us leaner, flatter, more nimble, and more responsive to the needs of the customer.
|
||||
|
||||
Many of the approaches were so transformational that their core principles still resonate with me today. Specific ideas and methods from thought leaders such as John Kotter, Peter Drucker, Edwards Demming, and Peter Senge were truly pivotal for our ability to rethink our work, as were the adoption of process improvement methods such as Six Sigma and those embodied in the "Toyota Way."
|
||||
|
||||
But others seemed to simply repackage these same ideas with a sexy new twist—hence my _deja vu_.
|
||||
|
||||
And yet when I began my career as a teacher, I encountered a context that _didn't_ give me that feeling: education. In fact, I was surprised to find that "getting better all the time" was _not_ the same high priority in my new profession that it was in my old one (particularly at the level of my role as a classroom teacher).
|
||||
|
||||
Why aren't more educational organizations working to create cultures of continuous improvement? I can think of several reasons, but let me address two.
|
||||
|
||||
### Widgets no more
|
||||
|
||||
The first barrier to a culture of continuous improvement is education's general reticence to look at other professions for ideas it can adapt and adopt—especially ideas from the business community. The second is education's predominant leadership model, which remains predominantly top-down and rooted in hierarchy. Conversations about systemic, continuous improvement tend to be the purview of a relatively small group of school or district leaders: principals, assistant principals, superintendents, and the like. But widespread organizational culture change can't occur if only one small group is involved in it.
|
||||
|
||||
Before unpacking these points a bit further, I'd like to emphasize that there are certainly exceptions to the above generalization (many I have seen first hand) and that there are two basic assumptions that I think any education stakeholder should be able to agree with:
|
||||
|
||||
1. Continuous improvement must be an essential mindset for _anyone_ involved in the work of providing high-quality and equitable teaching and learning systems for students, and
|
||||
2. Decisions by leaders of our schools will more greatly benefit students and the communities in which they live when those decisions are informed and influenced by those who work closest with students.
|
||||
|
||||
|
||||
|
||||
So why a tendency to ignore (or be outright hostile toward) ideas that come from outside the education space?
|
||||
|
||||
I, for example, have certainly faced criticism in the past for suggesting that we look to other professions for ideas and inspiration that can help us better meet the needs of students. A common refrain is something like: "You're trying to treat our students like widgets!" But how could our students be treated any more like widgets than they already are? They matriculate through school in age-based cohorts, going from siloed class to class each day by the sound of a shrill bell, and receive grades based on arbitrary tests that emphasize sameness over individuality.
|
||||
|
||||
What I'm advocating is a clear-eyed and objective look at any idea from any sector with potential to help us better meet the needs of individual students, not that we somehow run our schools like businesses.
|
||||
|
||||
It may be news to many inside of education, but widgets—abstract units of production that evoke the idea of assembly line standardization—are not a significant part of the modern manufacturing sector. Thanks to the culture of continuous improvement described above, modern, advanced manufacturing delivers just what the individual customer wants, at a competitive price, exactly when she wants it. If we adapted this model to our schools, teachers would be more likely to collaborate and constantly refine their unique paths of growth for all students based on just-in-time needs and desires—regardless of the time, subject, or any other traditional norm.
|
||||
|
||||
What I'm advocating is a clear-eyed and objective look at any idea from any sector with potential to help us better meet the needs of individual students, not that we somehow run our schools like businesses. In order for this to happen effectively, however, we need to scrutinize a leadership structure that has frankly remained stagnant for over 100 years.
|
||||
|
||||
### Toward continuous improvement
|
||||
|
||||
While I certainly appreciate the argument that education is an animal significantly different from other professions, I also believe that rethinking an organizational and leadership structure is an applicable exercise for any entity wanting to remain responsible (and responsive) to the needs of its stakeholders. Most other professions have taken a hard look at their traditional, closed, hierarchical structures and moved to ones that encourage collective autonomy per shared goals of excellence—organizational elements essential for continuous improvement. It's time our schools and districts do the same by expanding their horizon beyond sources that, while well intended, are developed from a lens of the current paradigm.
|
||||
|
||||
Not surprisingly, a go-to resource I recommend to any school wanting to begin or accelerate this process is _The Open Organization_ by Jim Whitehurst. Not only does the book provide a window into how educators can create more open, inclusive leadership structures—where mutual respect enables nimble decisions to be made per real-time data—but it does so in language easily adaptable to the rather strange lexicon that's second nature to educators. Open organization thinking provides pragmatic ways any organization can empower members to be more open: sharing ideas and resources, embracing a culture of collaborative participation as a top priority, developing an innovation mindset through rapid prototyping, valuing ideas based on merit rather than the rank of the person proposing them, and building a strong sense of community that's baked into the organization's DNA. Such an open organization crowd-sources ideas from both inside and outside its formal structure and creates the type of environment that enables localized, student-centered innovations to thrive.
|
||||
|
||||
We simply can't rely on solutions and practices we developed in a factory-model paradigm.
|
||||
|
||||
Here's the bottom line: Essential to a culture of continuous improvement is recognizing that what we've done in the past may not be suitable in a rapidly changing future. For educators, that means we simply can't rely on solutions and practices we developed in a factory-model paradigm. We must acknowledge countless examples of best practices from other sectors—such as non-profits, the military, the medical profession, and yes, even business—that can at least _inform_ how we rethink what we do in the best interest of students. By moving beyond the traditionally sanctioned "eduspeak" world, we create opportunities for considering perspectives. We can better see the forest for the trees, taking a more objective look at the problems we face, as well as acknowledging what we do very well.
|
||||
|
||||
Intentionally considering ideas from all sources—from first year classroom teachers to the latest NYT Business & Management Leadership bestseller—offers us a powerful way to engage existing talent within our schools to help overcome the institutionalized inertia that has prevented more positive change from taking hold in our schools and districts.
|
||||
|
||||
Relentlessly pursuing methods of continuous improvement should not be a behavior confined to organizations fighting to remain competitive in a global, innovation economy, nor should it be left to a select few charged with the operation of our schools. When everyone in an organization is always thinking about what they can do differently _today_ to improve what they did _yesterday_ , then you have an organization living a culture of excellence. That's the kind of radically collaborative and innovative culture we should especially expect for organizations focused on changing the lives of young people.
|
||||
|
||||
I'm eagerly awaiting the day when I enter a school, recognize that spirit, and smile to myself as I say, "I've seen this before."
|
||||
|
||||
Experiential learning using open source is fraught with opportunities for disaster.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/open-organization/19/4/education-culture-agile
|
||||
|
||||
作者：[Ben Owens][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://opensource.com/users/engineerteacher/users/ke4qqq/users/n8chz/users/don-watkins
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/EDUCATION_network.png?itok=ySEHuAQ8
|
||||
792
sources/tech/20190416 Detecting malaria with deep learning.md
Normal file
792
sources/tech/20190416 Detecting malaria with deep learning.md
Normal file
@@ -0,0 +1,792 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (Detecting malaria with deep learning)
|
||||
[#]: via: (https://opensource.com/article/19/4/detecting-malaria-deep-learning)
|
||||
[#]: author: (Dipanjan (DJ) Sarkar (Red Hat) https://opensource.com/users/djsarkar)
|
||||
|
||||
Detecting malaria with deep learning
|
||||
======
|
||||
Artificial intelligence combined with open source tools can improve
|
||||
diagnosis of the fatal disease malaria.
|
||||
![][1]
|
||||
|
||||
Artificial intelligence (AI) and open source tools, technologies, and frameworks are a powerful combination for improving society. _"Health is wealth"_ is perhaps a cliche, yet it's very accurate! In this article, we will examine how AI can be leveraged for detecting the deadly disease malaria with a low-cost, effective, and accurate open source deep learning solution.
|
||||
|
||||
While I am neither a doctor nor a healthcare researcher and I'm nowhere near as qualified as they are, I am interested in applying AI to healthcare research. My intent in this article is to showcase how AI and open source solutions can help malaria detection and reduce manual labor.
|
||||
|
||||
![Python and TensorFlow][2]
|
||||
|
||||
Python and TensorFlow: A great combo to build open source deep learning solutions
|
||||
|
||||
Thanks to the power of Python and deep learning frameworks like TensorFlow, we can build robust, scalable, and effective deep learning solutions. Because these tools are free and open source, we can build solutions that are very cost-effective and easily adopted and used by anyone. Let's get started!
|
||||
|
||||
### Motivation for the project
|
||||
|
||||
Malaria is a deadly, infectious, mosquito-borne disease caused by _Plasmodium_ parasites that are transmitted by the bites of infected female _Anopheles_ mosquitoes. There are five parasites that cause malaria, but two types— _P. falciparum_ and _P. vivax_ —cause the majority of the cases.
|
||||
|
||||
![Malaria heat map][3]
|
||||
|
||||
This map shows that malaria is prevalent around the globe, especially in tropical regions, but the nature and fatality of the disease is the primary motivation for this project.
|
||||
|
||||
If an infected mosquito bites you, parasites carried by the mosquito enter your blood and start destroying oxygen-carrying red blood cells (RBC). Typically, the first symptoms of malaria are similar to a virus like the flu and they usually begin within a few days or weeks after the mosquito bite. However, these deadly parasites can live in your body for over a year without causing symptoms, and a delay in treatment can lead to complications and even death. Therefore, early detection can save lives.
|
||||
|
||||
The World Health Organization's (WHO) [malaria facts][4] indicate that nearly half the world's population is at risk from malaria, and there are over 200 million malaria cases and approximately 400,000 deaths due to malaria every year. This is a motivatation to make malaria detection and diagnosis fast, easy, and effective.
|
||||
|
||||
### Methods of malaria detection
|
||||
|
||||
There are several methods that can be used for malaria detection and diagnosis. The paper on which our project is based, "[Pre-trained convolutional neural networks as feature extractors toward improved Malaria parasite detection in thin blood smear images][5]," by Rajaraman, et al., introduces some of the methods, including polymerase chain reaction (PCR) and rapid diagnostic tests (RDT). These two tests are typically used where high-quality microscopy services are not readily available.
|
||||
|
||||
The standard malaria diagnosis is typically based on a blood-smear workflow, according to Carlos Ariza's article "[Malaria Hero: A web app for faster malaria diagnosis][6]," which I learned about in Adrian Rosebrock's "[Deep learning and medical image analysis with Keras][7]." I appreciate the authors of these excellent resources for giving me more perspective on malaria prevalence, diagnosis, and treatment.
|
||||
|
||||
![Blood smear workflow for Malaria detection][8]
|
||||
|
||||
A blood smear workflow for Malaria detection
|
||||
|
||||
According to WHO protocol, diagnosis typically involves intensive examination of the blood smear at 100X magnification. Trained people manually count how many red blood cells contain parasites out of 5,000 cells. As the Rajaraman, et al., paper cited above explains:
|
||||
|
||||
> Thick blood smears assist in detecting the presence of parasites while thin blood smears assist in identifying the species of the parasite causing the infection (Centers for Disease Control and Prevention, 2012). The diagnostic accuracy heavily depends on human expertise and can be adversely impacted by the inter-observer variability and the liability imposed by large-scale diagnoses in disease-endemic/resource-constrained regions (Mitiku, Mengistu, and Gelaw, 2003). Alternative techniques such as polymerase chain reaction (PCR) and rapid diagnostic tests (RDT) are used; however, PCR analysis is limited in its performance (Hommelsheim, et al., 2014) and RDTs are less cost-effective in disease-endemic regions (Hawkes, Katsuva, and Masumbuko, 2009).
|
||||
|
||||
Thus, malaria detection could benefit from automation using deep learning.
|
||||
|
||||
### Deep learning for malaria detection
|
||||
|
||||
Manual diagnosis of blood smears is an intensive manual process that requires expertise in classifying and counting parasitized and uninfected cells. This process may not scale well, especially in regions where the right expertise is hard to find. Some advancements have been made in leveraging state-of-the-art image processing and analysis techniques to extract hand-engineered features and build machine learning-based classification models. However, these models are not scalable with more data being available for training and given the fact that hand-engineered features take a lot of time.
|
||||
|
||||
Deep learning models, or more specifically convolutional neural networks (CNNs), have proven very effective in a wide variety of computer vision tasks. (If you would like additional background knowledge on CNNs, I recommend reading [CS231n Convolutional Neural Networks for Visual Recognition][9].) Briefly, the key layers in a CNN model include convolution and pooling layers, as shown in the following figure.
|
||||
|
||||
![A typical CNN architecture][10]
|
||||
|
||||
A typical CNN architecture
|
||||
|
||||
Convolution layers learn spatial hierarchical patterns from data, which are also translation-invariant, so they are able to learn different aspects of images. For example, the first convolution layer will learn small and local patterns, such as edges and corners, a second convolution layer will learn larger patterns based on the features from the first layers, and so on. This allows CNNs to automate feature engineering and learn effective features that generalize well on new data points. Pooling layers helps with downsampling and dimension reduction.
|
||||
|
||||
Thus, CNNs help with automated and scalable feature engineering. Also, plugging in dense layers at the end of the model enables us to perform tasks like image classification. Automated malaria detection using deep learning models like CNNs could be very effective, cheap, and scalable, especially with the advent of transfer learning and pre-trained models that work quite well, even with constraints like less data.
|
||||
|
||||
The Rajaraman, et al., paper leverages six pre-trained models on a dataset to obtain an impressive accuracy of 95.9% in detecting malaria vs. non-infected samples. Our focus is to try some simple CNN models from scratch and a couple of pre-trained models using transfer learning to see the results we can get on the same dataset. We will use open source tools and frameworks, including Python and TensorFlow, to build our models.
|
||||
|
||||
### The dataset
|
||||
|
||||
The data for our analysis comes from researchers at the Lister Hill National Center for Biomedical Communications (LHNCBC), part of the National Library of Medicine (NLM), who have carefully collected and annotated the [publicly available dataset][11] of healthy and infected blood smear images. These researchers have developed a mobile [application for malaria detection][12] that runs on a standard Android smartphone attached to a conventional light microscope. They used Giemsa-stained thin blood smear slides from 150 _P. falciparum_ -infected and 50 healthy patients, collected and photographed at Chittagong Medical College Hospital, Bangladesh. The smartphone's built-in camera acquired images of slides for each microscopic field of view. The images were manually annotated by an expert slide reader at the Mahidol-Oxford Tropical Medicine Research Unit in Bangkok, Thailand.
|
||||
|
||||
Let's briefly check out the dataset's structure. First, I will install some basic dependencies (based on the operating system being used).
|
||||
|
||||
![Installing dependencies][13]
|
||||
|
||||
I am using a Debian-based system on the cloud with a GPU so I can run my models faster. To view the directory structure, we must install the tree dependency (if we don't have it) using **sudo apt install tree**.
|
||||
|
||||
![Installing the tree dependency][14]
|
||||
|
||||
We have two folders that contain images of cells, infected and healthy. We can get further details about the total number of images by entering:
|
||||
|
||||
|
||||
```
|
||||
import os
|
||||
import glob
|
||||
|
||||
base_dir = os.path.join('./cell_images')
|
||||
infected_dir = os.path.join(base_dir,'Parasitized')
|
||||
healthy_dir = os.path.join(base_dir,'Uninfected')
|
||||
|
||||
infected_files = glob.glob(infected_dir+'/*.png')
|
||||
healthy_files = glob.glob(healthy_dir+'/*.png')
|
||||
len(infected_files), len(healthy_files)
|
||||
|
||||
# Output
|
||||
(13779, 13779)
|
||||
```
|
||||
|
||||
It looks like we have a balanced dataset with 13,779 malaria and 13,779 non-malaria (uninfected) cell images. Let's build a data frame from this, which we will use when we start building our datasets.
|
||||
|
||||
|
||||
```
|
||||
import numpy as np
|
||||
import pandas as pd
|
||||
|
||||
np.random.seed(42)
|
||||
|
||||
files_df = pd.DataFrame({
|
||||
'filename': infected_files + healthy_files,
|
||||
'label': ['malaria'] * len(infected_files) + ['healthy'] * len(healthy_files)
|
||||
}).sample(frac=1, random_state=42).reset_index(drop=True)
|
||||
|
||||
files_df.head()
|
||||
```
|
||||
|
||||
![Datasets][15]
|
||||
|
||||
### Build and explore image datasets
|
||||
|
||||
To build deep learning models, we need training data, but we also need to test the model's performance on unseen data. We will use a 60:10:30 split for train, validation, and test datasets, respectively. We will leverage the train and validation datasets during training and check the performance of the model on the test dataset.
|
||||
|
||||
|
||||
```
|
||||
from sklearn.model_selection import train_test_split
|
||||
from collections import Counter
|
||||
|
||||
train_files, test_files, train_labels, test_labels = train_test_split(files_df['filename'].values,
|
||||
files_df['label'].values,
|
||||
test_size=0.3, random_state=42)
|
||||
train_files, val_files, train_labels, val_labels = train_test_split(train_files,
|
||||
train_labels,
|
||||
test_size=0.1, random_state=42)
|
||||
|
||||
print(train_files.shape, val_files.shape, test_files.shape)
|
||||
print('Train:', Counter(train_labels), '\nVal:', Counter(val_labels), '\nTest:', Counter(test_labels))
|
||||
|
||||
# Output
|
||||
(17361,) (1929,) (8268,)
|
||||
Train: Counter({'healthy': 8734, 'malaria': 8627})
|
||||
Val: Counter({'healthy': 970, 'malaria': 959})
|
||||
Test: Counter({'malaria': 4193, 'healthy': 4075})
|
||||
```
|
||||
|
||||
The images will not be of equal dimensions because blood smears and cell images vary based on the human, the test method, and the orientation of the photo. Let's get some summary statistics of our training dataset to determine the optimal image dimensions (remember, we don't touch the test dataset at all!).
|
||||
|
||||
|
||||
```
|
||||
import cv2
|
||||
from concurrent import futures
|
||||
import threading
|
||||
|
||||
def get_img_shape_parallel(idx, img, total_imgs):
|
||||
if idx % 5000 == 0 or idx == (total_imgs - 1):
|
||||
print('{}: working on img num: {}'.format(threading.current_thread().name,
|
||||
idx))
|
||||
return cv2.imread(img).shape
|
||||
|
||||
ex = futures.ThreadPoolExecutor(max_workers=None)
|
||||
data_inp = [(idx, img, len(train_files)) for idx, img in enumerate(train_files)]
|
||||
print('Starting Img shape computation:')
|
||||
train_img_dims_map = ex.map(get_img_shape_parallel,
|
||||
[record[0] for record in data_inp],
|
||||
[record[1] for record in data_inp],
|
||||
[record[2] for record in data_inp])
|
||||
train_img_dims = list(train_img_dims_map)
|
||||
print('Min Dimensions:', np.min(train_img_dims, axis=0))
|
||||
print('Avg Dimensions:', np.mean(train_img_dims, axis=0))
|
||||
print('Median Dimensions:', np.median(train_img_dims, axis=0))
|
||||
print('Max Dimensions:', np.max(train_img_dims, axis=0))
|
||||
|
||||
# Output
|
||||
Starting Img shape computation:
|
||||
ThreadPoolExecutor-0_0: working on img num: 0
|
||||
ThreadPoolExecutor-0_17: working on img num: 5000
|
||||
ThreadPoolExecutor-0_15: working on img num: 10000
|
||||
ThreadPoolExecutor-0_1: working on img num: 15000
|
||||
ThreadPoolExecutor-0_7: working on img num: 17360
|
||||
Min Dimensions: [46 46 3]
|
||||
Avg Dimensions: [132.77311215 132.45757733 3.]
|
||||
Median Dimensions: [130. 130. 3.]
|
||||
Max Dimensions: [385 394 3]
|
||||
```
|
||||
|
||||
We apply parallel processing to speed up the image-read operations and, based on the summary statistics, we will resize each image to 125x125 pixels. Let's load up all of our images and resize them to these fixed dimensions.
|
||||
|
||||
|
||||
```
|
||||
IMG_DIMS = (125, 125)
|
||||
|
||||
def get_img_data_parallel(idx, img, total_imgs):
|
||||
if idx % 5000 == 0 or idx == (total_imgs - 1):
|
||||
print('{}: working on img num: {}'.format(threading.current_thread().name,
|
||||
idx))
|
||||
img = cv2.imread(img)
|
||||
img = cv2.resize(img, dsize=IMG_DIMS,
|
||||
interpolation=cv2.INTER_CUBIC)
|
||||
img = np.array(img, dtype=np.float32)
|
||||
return img
|
||||
|
||||
ex = futures.ThreadPoolExecutor(max_workers=None)
|
||||
train_data_inp = [(idx, img, len(train_files)) for idx, img in enumerate(train_files)]
|
||||
val_data_inp = [(idx, img, len(val_files)) for idx, img in enumerate(val_files)]
|
||||
test_data_inp = [(idx, img, len(test_files)) for idx, img in enumerate(test_files)]
|
||||
|
||||
print('Loading Train Images:')
|
||||
train_data_map = ex.map(get_img_data_parallel,
|
||||
[record[0] for record in train_data_inp],
|
||||
[record[1] for record in train_data_inp],
|
||||
[record[2] for record in train_data_inp])
|
||||
train_data = np.array(list(train_data_map))
|
||||
|
||||
print('\nLoading Validation Images:')
|
||||
val_data_map = ex.map(get_img_data_parallel,
|
||||
[record[0] for record in val_data_inp],
|
||||
[record[1] for record in val_data_inp],
|
||||
[record[2] for record in val_data_inp])
|
||||
val_data = np.array(list(val_data_map))
|
||||
|
||||
print('\nLoading Test Images:')
|
||||
test_data_map = ex.map(get_img_data_parallel,
|
||||
[record[0] for record in test_data_inp],
|
||||
[record[1] for record in test_data_inp],
|
||||
[record[2] for record in test_data_inp])
|
||||
test_data = np.array(list(test_data_map))
|
||||
|
||||
train_data.shape, val_data.shape, test_data.shape
|
||||
|
||||
# Output
|
||||
Loading Train Images:
|
||||
ThreadPoolExecutor-1_0: working on img num: 0
|
||||
ThreadPoolExecutor-1_12: working on img num: 5000
|
||||
ThreadPoolExecutor-1_6: working on img num: 10000
|
||||
ThreadPoolExecutor-1_10: working on img num: 15000
|
||||
ThreadPoolExecutor-1_3: working on img num: 17360
|
||||
|
||||
Loading Validation Images:
|
||||
ThreadPoolExecutor-1_13: working on img num: 0
|
||||
ThreadPoolExecutor-1_18: working on img num: 1928
|
||||
|
||||
Loading Test Images:
|
||||
ThreadPoolExecutor-1_5: working on img num: 0
|
||||
ThreadPoolExecutor-1_19: working on img num: 5000
|
||||
ThreadPoolExecutor-1_8: working on img num: 8267
|
||||
((17361, 125, 125, 3), (1929, 125, 125, 3), (8268, 125, 125, 3))
|
||||
```
|
||||
|
||||
We leverage parallel processing again to speed up computations pertaining to image load and resizing. Finally, we get our image tensors of the desired dimensions, as depicted in the preceding output. We can now view some sample cell images to get an idea of how our data looks.
|
||||
|
||||
|
||||
```
|
||||
import matplotlib.pyplot as plt
|
||||
%matplotlib inline
|
||||
|
||||
plt.figure(1 , figsize = (8 , 8))
|
||||
n = 0
|
||||
for i in range(16):
|
||||
n += 1
|
||||
r = np.random.randint(0 , train_data.shape[0] , 1)
|
||||
plt.subplot(4 , 4 , n)
|
||||
plt.subplots_adjust(hspace = 0.5 , wspace = 0.5)
|
||||
plt.imshow(train_data[r[0]]/255.)
|
||||
plt.title('{}'.format(train_labels[r[0]]))
|
||||
plt.xticks([]) , plt.yticks([])
|
||||
```
|
||||
|
||||
![Malaria cell samples][16]
|
||||
|
||||
Based on these sample images, we can see some subtle differences between malaria and healthy cell images. We will make our deep learning models try to learn these patterns during model training.
|
||||
|
||||
Before can we start training our models, we must set up some basic configuration settings.
|
||||
|
||||
|
||||
```
|
||||
BATCH_SIZE = 64
|
||||
NUM_CLASSES = 2
|
||||
EPOCHS = 25
|
||||
INPUT_SHAPE = (125, 125, 3)
|
||||
|
||||
train_imgs_scaled = train_data / 255.
|
||||
val_imgs_scaled = val_data / 255.
|
||||
|
||||
# encode text category labels
|
||||
from sklearn.preprocessing import LabelEncoder
|
||||
|
||||
le = LabelEncoder()
|
||||
le.fit(train_labels)
|
||||
train_labels_enc = le.transform(train_labels)
|
||||
val_labels_enc = le.transform(val_labels)
|
||||
|
||||
print(train_labels[:6], train_labels_enc[:6])
|
||||
|
||||
# Output
|
||||
['malaria' 'malaria' 'malaria' 'healthy' 'healthy' 'malaria'] [1 1 1 0 0 1]
|
||||
```
|
||||
|
||||
We fix our image dimensions, batch size, and epochs and encode our categorical class labels. The alpha version of TensorFlow 2.0 was released in March 2019, and this exercise is the perfect excuse to try it out.
|
||||
|
||||
|
||||
```
|
||||
import tensorflow as tf
|
||||
|
||||
# Load the TensorBoard notebook extension (optional)
|
||||
%load_ext tensorboard.notebook
|
||||
|
||||
tf.random.set_seed(42)
|
||||
tf.__version__
|
||||
|
||||
# Output
|
||||
'2.0.0-alpha0'
|
||||
```
|
||||
|
||||
### Deep learning model training
|
||||
|
||||
In the model training phase, we will build three deep learning models, train them with our training data, and compare their performance using the validation data. We will then save these models and use them later in the model evaluation phase.
|
||||
|
||||
#### Model 1: CNN from scratch
|
||||
|
||||
Our first malaria detection model will build and train a basic CNN from scratch. First, let's define our model architecture.
|
||||
|
||||
|
||||
```
|
||||
inp = tf.keras.layers.Input(shape=INPUT_SHAPE)
|
||||
|
||||
conv1 = tf.keras.layers.Conv2D(32, kernel_size=(3, 3),
|
||||
activation='relu', padding='same')(inp)
|
||||
pool1 = tf.keras.layers.MaxPooling2D(pool_size=(2, 2))(conv1)
|
||||
conv2 = tf.keras.layers.Conv2D(64, kernel_size=(3, 3),
|
||||
activation='relu', padding='same')(pool1)
|
||||
pool2 = tf.keras.layers.MaxPooling2D(pool_size=(2, 2))(conv2)
|
||||
conv3 = tf.keras.layers.Conv2D(128, kernel_size=(3, 3),
|
||||
activation='relu', padding='same')(pool2)
|
||||
pool3 = tf.keras.layers.MaxPooling2D(pool_size=(2, 2))(conv3)
|
||||
|
||||
flat = tf.keras.layers.Flatten()(pool3)
|
||||
|
||||
hidden1 = tf.keras.layers.Dense(512, activation='relu')(flat)
|
||||
drop1 = tf.keras.layers.Dropout(rate=0.3)(hidden1)
|
||||
hidden2 = tf.keras.layers.Dense(512, activation='relu')(drop1)
|
||||
drop2 = tf.keras.layers.Dropout(rate=0.3)(hidden2)
|
||||
|
||||
out = tf.keras.layers.Dense(1, activation='sigmoid')(drop2)
|
||||
|
||||
model = tf.keras.Model(inputs=inp, outputs=out)
|
||||
model.compile(optimizer='adam',
|
||||
loss='binary_crossentropy',
|
||||
metrics=['accuracy'])
|
||||
model.summary()
|
||||
|
||||
# Output
|
||||
Model: "model"
|
||||
_________________________________________________________________
|
||||
Layer (type) Output Shape Param #
|
||||
=================================================================
|
||||
input_1 (InputLayer) [(None, 125, 125, 3)] 0
|
||||
_________________________________________________________________
|
||||
conv2d (Conv2D) (None, 125, 125, 32) 896
|
||||
_________________________________________________________________
|
||||
max_pooling2d (MaxPooling2D) (None, 62, 62, 32) 0
|
||||
_________________________________________________________________
|
||||
conv2d_1 (Conv2D) (None, 62, 62, 64) 18496
|
||||
_________________________________________________________________
|
||||
...
|
||||
...
|
||||
_________________________________________________________________
|
||||
dense_1 (Dense) (None, 512) 262656
|
||||
_________________________________________________________________
|
||||
dropout_1 (Dropout) (None, 512) 0
|
||||
_________________________________________________________________
|
||||
dense_2 (Dense) (None, 1) 513
|
||||
=================================================================
|
||||
Total params: 15,102,529
|
||||
Trainable params: 15,102,529
|
||||
Non-trainable params: 0
|
||||
_________________________________________________________________
|
||||
```
|
||||
|
||||
Based on the architecture in this code, our CNN model has three convolution and pooling layers, followed by two dense layers, and dropouts for regularization. Let's train our model.
|
||||
|
||||
|
||||
```
|
||||
import datetime
|
||||
|
||||
logdir = os.path.join('/home/dipanzan_sarkar/projects/tensorboard_logs',
|
||||
datetime.datetime.now().strftime("%Y%m%d-%H%M%S"))
|
||||
tensorboard_callback = tf.keras.callbacks.TensorBoard(logdir, histogram_freq=1)
|
||||
reduce_lr = tf.keras.callbacks.ReduceLROnPlateau(monitor='val_loss', factor=0.5,
|
||||
patience=2, min_lr=0.000001)
|
||||
callbacks = [reduce_lr, tensorboard_callback]
|
||||
|
||||
history = model.fit(x=train_imgs_scaled, y=train_labels_enc,
|
||||
batch_size=BATCH_SIZE,
|
||||
epochs=EPOCHS,
|
||||
validation_data=(val_imgs_scaled, val_labels_enc),
|
||||
callbacks=callbacks,
|
||||
verbose=1)
|
||||
|
||||
|
||||
# Output
|
||||
Train on 17361 samples, validate on 1929 samples
|
||||
Epoch 1/25
|
||||
17361/17361 [====] - 32s 2ms/sample - loss: 0.4373 - accuracy: 0.7814 - val_loss: 0.1834 - val_accuracy: 0.9393
|
||||
Epoch 2/25
|
||||
17361/17361 [====] - 30s 2ms/sample - loss: 0.1725 - accuracy: 0.9434 - val_loss: 0.1567 - val_accuracy: 0.9513
|
||||
...
|
||||
...
|
||||
Epoch 24/25
|
||||
17361/17361 [====] - 30s 2ms/sample - loss: 0.0036 - accuracy: 0.9993 - val_loss: 0.3693 - val_accuracy: 0.9565
|
||||
Epoch 25/25
|
||||
17361/17361 [====] - 30s 2ms/sample - loss: 0.0034 - accuracy: 0.9994 - val_loss: 0.3699 - val_accuracy: 0.9559
|
||||
```
|
||||
|
||||
We get a validation accuracy of 95.6%, which is pretty good, although our model looks to be overfitting slightly (based on looking at our training accuracy, which is 99.9%). We can get a clear perspective on this by plotting the training and validation accuracy and loss curves.
|
||||
|
||||
|
||||
```
|
||||
f, (ax1, ax2) = plt.subplots(1, 2, figsize=(12, 4))
|
||||
t = f.suptitle('Basic CNN Performance', fontsize=12)
|
||||
f.subplots_adjust(top=0.85, wspace=0.3)
|
||||
|
||||
max_epoch = len(history.history['accuracy'])+1
|
||||
epoch_list = list(range(1,max_epoch))
|
||||
ax1.plot(epoch_list, history.history['accuracy'], label='Train Accuracy')
|
||||
ax1.plot(epoch_list, history.history['val_accuracy'], label='Validation Accuracy')
|
||||
ax1.set_xticks(np.arange(1, max_epoch, 5))
|
||||
ax1.set_ylabel('Accuracy Value')
|
||||
ax1.set_xlabel('Epoch')
|
||||
ax1.set_title('Accuracy')
|
||||
l1 = ax1.legend(loc="best")
|
||||
|
||||
ax2.plot(epoch_list, history.history['loss'], label='Train Loss')
|
||||
ax2.plot(epoch_list, history.history['val_loss'], label='Validation Loss')
|
||||
ax2.set_xticks(np.arange(1, max_epoch, 5))
|
||||
ax2.set_ylabel('Loss Value')
|
||||
ax2.set_xlabel('Epoch')
|
||||
ax2.set_title('Loss')
|
||||
l2 = ax2.legend(loc="best")
|
||||
```
|
||||
|
||||
![Learning curves for basic CNN][17]
|
||||
|
||||
Learning curves for basic CNN
|
||||
|
||||
We can see after the fifth epoch that things don't seem to improve a whole lot overall. Let's save this model for future evaluation.
|
||||
|
||||
|
||||
```
|
||||
`model.save('basic_cnn.h5')`
|
||||
```
|
||||
|
||||
#### Deep transfer learning
|
||||
|
||||
Just like humans have an inherent capability to transfer knowledge across tasks, transfer learning enables us to utilize knowledge from previously learned tasks and apply it to newer, related ones, even in the context of machine learning or deep learning. If you are interested in doing a deep-dive on transfer learning, you can read my article "[A comprehensive hands-on guide to transfer learning with real-world applications in deep learning][18]" and my book [_Hands-On Transfer Learning with Python_][19].
|
||||
|
||||
![Ideas for deep transfer learning][20]
|
||||
|
||||
The idea we want to explore in this exercise is:
|
||||
|
||||
> Can we leverage a pre-trained deep learning model (which was trained on a large dataset, like ImageNet) to solve the problem of malaria detection by applying and transferring its knowledge in the context of our problem?
|
||||
|
||||
We will apply the two most popular strategies for deep transfer learning.
|
||||
|
||||
* Pre-trained model as a feature extractor
|
||||
* Pre-trained model with fine-tuning
|
||||
|
||||
|
||||
|
||||
We will be using the pre-trained VGG-19 deep learning model, developed by the Visual Geometry Group (VGG) at the University of Oxford, for our experiments. A pre-trained model like VGG-19 is trained on a huge dataset ([ImageNet][21]) with a lot of diverse image categories. Therefore, the model should have learned a robust hierarchy of features, which are spatial-, rotational-, and translation-invariant with regard to features learned by CNN models. Hence, the model, having learned a good representation of features for over a million images, can act as a good feature extractor for new images suitable for computer vision problems like malaria detection. Let's discuss the VGG-19 model architecture before unleashing the power of transfer learning on our problem.
|
||||
|
||||
##### Understanding the VGG-19 model
|
||||
|
||||
The VGG-19 model is a 19-layer (convolution and fully connected) deep learning network built on the ImageNet database, which was developed for the purpose of image recognition and classification. This model was built by Karen Simonyan and Andrew Zisserman and is described in their paper "[Very deep convolutional networks for large-scale image recognition][22]." The architecture of the VGG-19 model is:
|
||||
|
||||
![VGG-19 Model Architecture][23]
|
||||
|
||||
You can see that we have a total of 16 convolution layers using 3x3 convolution filters along with max pooling layers for downsampling and two fully connected hidden layers of 4,096 units in each layer followed by a dense layer of 1,000 units, where each unit represents one of the image categories in the ImageNet database. We do not need the last three layers since we will be using our own fully connected dense layers to predict malaria. We are more concerned with the first five blocks so we can leverage the VGG model as an effective feature extractor.
|
||||
|
||||
We will use one of the models as a simple feature extractor by freezing the five convolution blocks to make sure their weights aren't updated after each epoch. For the last model, we will apply fine-tuning to the VGG model, where we will unfreeze the last two blocks (Block 4 and Block 5) so that their weights will be updated in each epoch (per batch of data) as we train our own model.
|
||||
|
||||
#### Model 2: Pre-trained model as a feature extractor
|
||||
|
||||
For building this model, we will leverage TensorFlow to load up the VGG-19 model and freeze the convolution blocks so we can use them as an image feature extractor. We will plug in our own dense layers at the end to perform the classification task.
|
||||
|
||||
|
||||
```
|
||||
vgg = tf.keras.applications.vgg19.VGG19(include_top=False, weights='imagenet',
|
||||
input_shape=INPUT_SHAPE)
|
||||
vgg.trainable = False
|
||||
# Freeze the layers
|
||||
for layer in vgg.layers:
|
||||
layer.trainable = False
|
||||
|
||||
base_vgg = vgg
|
||||
base_out = base_vgg.output
|
||||
pool_out = tf.keras.layers.Flatten()(base_out)
|
||||
hidden1 = tf.keras.layers.Dense(512, activation='relu')(pool_out)
|
||||
drop1 = tf.keras.layers.Dropout(rate=0.3)(hidden1)
|
||||
hidden2 = tf.keras.layers.Dense(512, activation='relu')(drop1)
|
||||
drop2 = tf.keras.layers.Dropout(rate=0.3)(hidden2)
|
||||
|
||||
out = tf.keras.layers.Dense(1, activation='sigmoid')(drop2)
|
||||
|
||||
model = tf.keras.Model(inputs=base_vgg.input, outputs=out)
|
||||
model.compile(optimizer=tf.keras.optimizers.RMSprop(lr=1e-4),
|
||||
loss='binary_crossentropy',
|
||||
metrics=['accuracy'])
|
||||
model.summary()
|
||||
|
||||
# Output
|
||||
Model: "model_1"
|
||||
_________________________________________________________________
|
||||
Layer (type) Output Shape Param #
|
||||
=================================================================
|
||||
input_2 (InputLayer) [(None, 125, 125, 3)] 0
|
||||
_________________________________________________________________
|
||||
block1_conv1 (Conv2D) (None, 125, 125, 64) 1792
|
||||
_________________________________________________________________
|
||||
block1_conv2 (Conv2D) (None, 125, 125, 64) 36928
|
||||
_________________________________________________________________
|
||||
...
|
||||
...
|
||||
_________________________________________________________________
|
||||
block5_pool (MaxPooling2D) (None, 3, 3, 512) 0
|
||||
_________________________________________________________________
|
||||
flatten_1 (Flatten) (None, 4608) 0
|
||||
_________________________________________________________________
|
||||
dense_3 (Dense) (None, 512) 2359808
|
||||
_________________________________________________________________
|
||||
dropout_2 (Dropout) (None, 512) 0
|
||||
_________________________________________________________________
|
||||
dense_4 (Dense) (None, 512) 262656
|
||||
_________________________________________________________________
|
||||
dropout_3 (Dropout) (None, 512) 0
|
||||
_________________________________________________________________
|
||||
dense_5 (Dense) (None, 1) 513
|
||||
=================================================================
|
||||
Total params: 22,647,361
|
||||
Trainable params: 2,622,977
|
||||
Non-trainable params: 20,024,384
|
||||
_________________________________________________________________
|
||||
```
|
||||
|
||||
It is evident from this output that we have a lot of layers in our model and we will be using the frozen layers of the VGG-19 model as feature extractors only. You can use the following code to verify how many layers in our model are indeed trainable and how many total layers are present in our network.
|
||||
|
||||
|
||||
```
|
||||
print("Total Layers:", len(model.layers))
|
||||
print("Total trainable layers:",
|
||||
sum([1 for l in model.layers if l.trainable]))
|
||||
|
||||
# Output
|
||||
Total Layers: 28
|
||||
Total trainable layers: 6
|
||||
```
|
||||
|
||||
We will now train our model using similar configurations and callbacks to the ones we used in our previous model. Refer to [my GitHub repository][24] for the complete code to train the model. We observe the following plots showing the model's accuracy and loss.
|
||||
|
||||
![Learning curves for frozen pre-trained CNN][25]
|
||||
|
||||
Learning curves for frozen pre-trained CNN
|
||||
|
||||
This shows that our model is not overfitting as much as our basic CNN model, but the performance is slightly less than our basic CNN model. Let's save this model for future evaluation.
|
||||
|
||||
|
||||
```
|
||||
`model.save('vgg_frozen.h5')`
|
||||
```
|
||||
|
||||
#### Model 3: Fine-tuned pre-trained model with image augmentation
|
||||
|
||||
In our final model, we will fine-tune the weights of the layers in the last two blocks of our pre-trained VGG-19 model. We will also introduce the concept of image augmentation. The idea behind image augmentation is exactly as the name sounds. We load in existing images from our training dataset and apply some image transformation operations to them, such as rotation, shearing, translation, zooming, and so on, to produce new, altered versions of existing images. Due to these random transformations, we don't get the same images each time. We will leverage an excellent utility called **ImageDataGenerator** in **tf.keras** that can help build image augmentors.
|
||||
|
||||
|
||||
```
|
||||
train_datagen = tf.keras.preprocessing.image.ImageDataGenerator(rescale=1./255,
|
||||
zoom_range=0.05,
|
||||
rotation_range=25,
|
||||
width_shift_range=0.05,
|
||||
height_shift_range=0.05,
|
||||
shear_range=0.05, horizontal_flip=True,
|
||||
fill_mode='nearest')
|
||||
|
||||
val_datagen = tf.keras.preprocessing.image.ImageDataGenerator(rescale=1./255)
|
||||
|
||||
# build image augmentation generators
|
||||
train_generator = train_datagen.flow(train_data, train_labels_enc, batch_size=BATCH_SIZE, shuffle=True)
|
||||
val_generator = val_datagen.flow(val_data, val_labels_enc, batch_size=BATCH_SIZE, shuffle=False)
|
||||
```
|
||||
|
||||
We will not apply any transformations on our validation dataset (except for scaling the images, which is mandatory) since we will be using it to evaluate our model performance per epoch. For a detailed explanation of image augmentation in the context of transfer learning, feel free to check out my [article][18] cited above. Let's look at some sample results from a batch of image augmentation transforms.
|
||||
|
||||
|
||||
```
|
||||
img_id = 0
|
||||
sample_generator = train_datagen.flow(train_data[img_id:img_id+1], train_labels[img_id:img_id+1],
|
||||
batch_size=1)
|
||||
sample = [next(sample_generator) for i in range(0,5)]
|
||||
fig, ax = plt.subplots(1,5, figsize=(16, 6))
|
||||
print('Labels:', [item[1][0] for item in sample])
|
||||
l = [ax[i].imshow(sample[i][0][0]) for i in range(0,5)]
|
||||
```
|
||||
|
||||
![Sample augmented images][26]
|
||||
|
||||
You can clearly see the slight variations of our images in the preceding output. We will now build our deep learning model, making sure the last two blocks of the VGG-19 model are trainable.
|
||||
|
||||
|
||||
```
|
||||
vgg = tf.keras.applications.vgg19.VGG19(include_top=False, weights='imagenet',
|
||||
input_shape=INPUT_SHAPE)
|
||||
# Freeze the layers
|
||||
vgg.trainable = True
|
||||
|
||||
set_trainable = False
|
||||
for layer in vgg.layers:
|
||||
if layer.name in ['block5_conv1', 'block4_conv1']:
|
||||
set_trainable = True
|
||||
if set_trainable:
|
||||
layer.trainable = True
|
||||
else:
|
||||
layer.trainable = False
|
||||
|
||||
base_vgg = vgg
|
||||
base_out = base_vgg.output
|
||||
pool_out = tf.keras.layers.Flatten()(base_out)
|
||||
hidden1 = tf.keras.layers.Dense(512, activation='relu')(pool_out)
|
||||
drop1 = tf.keras.layers.Dropout(rate=0.3)(hidden1)
|
||||
hidden2 = tf.keras.layers.Dense(512, activation='relu')(drop1)
|
||||
drop2 = tf.keras.layers.Dropout(rate=0.3)(hidden2)
|
||||
|
||||
out = tf.keras.layers.Dense(1, activation='sigmoid')(drop2)
|
||||
|
||||
model = tf.keras.Model(inputs=base_vgg.input, outputs=out)
|
||||
model.compile(optimizer=tf.keras.optimizers.RMSprop(lr=1e-5),
|
||||
loss='binary_crossentropy',
|
||||
metrics=['accuracy'])
|
||||
|
||||
print("Total Layers:", len(model.layers))
|
||||
print("Total trainable layers:", sum([1 for l in model.layers if l.trainable]))
|
||||
|
||||
# Output
|
||||
Total Layers: 28
|
||||
Total trainable layers: 16
|
||||
```
|
||||
|
||||
We reduce the learning rate in our model since we don't want to make to large weight updates to the pre-trained layers when fine-tuning. The model's training process will be slightly different since we are using data generators, so we will be leveraging the **fit_generator(…)** function.
|
||||
|
||||
|
||||
```
|
||||
tensorboard_callback = tf.keras.callbacks.TensorBoard(logdir, histogram_freq=1)
|
||||
reduce_lr = tf.keras.callbacks.ReduceLROnPlateau(monitor='val_loss', factor=0.5,
|
||||
patience=2, min_lr=0.000001)
|
||||
|
||||
callbacks = [reduce_lr, tensorboard_callback]
|
||||
train_steps_per_epoch = train_generator.n // train_generator.batch_size
|
||||
val_steps_per_epoch = val_generator.n // val_generator.batch_size
|
||||
history = model.fit_generator(train_generator, steps_per_epoch=train_steps_per_epoch, epochs=EPOCHS,
|
||||
validation_data=val_generator, validation_steps=val_steps_per_epoch,
|
||||
verbose=1)
|
||||
|
||||
# Output
|
||||
Epoch 1/25
|
||||
271/271 [====] - 133s 489ms/step - loss: 0.2267 - accuracy: 0.9117 - val_loss: 0.1414 - val_accuracy: 0.9531
|
||||
Epoch 2/25
|
||||
271/271 [====] - 129s 475ms/step - loss: 0.1399 - accuracy: 0.9552 - val_loss: 0.1292 - val_accuracy: 0.9589
|
||||
...
|
||||
...
|
||||
Epoch 24/25
|
||||
271/271 [====] - 128s 473ms/step - loss: 0.0815 - accuracy: 0.9727 - val_loss: 0.1466 - val_accuracy: 0.9682
|
||||
Epoch 25/25
|
||||
271/271 [====] - 128s 473ms/step - loss: 0.0792 - accuracy: 0.9729 - val_loss: 0.1127 - val_accuracy: 0.9641
|
||||
```
|
||||
|
||||
This looks to be our best model yet. It gives us a validation accuracy of almost 96.5% and, based on the training accuracy, it doesn't look like our model is overfitting as much as our first model. This can be verified with the following learning curves.
|
||||
|
||||
![Learning curves for fine-tuned pre-trained CNN][27]
|
||||
|
||||
Learning curves for fine-tuned pre-trained CNN
|
||||
|
||||
Let's save this model so we can use it for model evaluation on our test dataset.
|
||||
|
||||
|
||||
```
|
||||
`model.save('vgg_finetuned.h5')`
|
||||
```
|
||||
|
||||
This completes our model training phase. We are now ready to test the performance of our models on the actual test dataset!
|
||||
|
||||
### Deep learning model performance evaluation
|
||||
|
||||
We will evaluate the three models we built in the training phase by making predictions with them on the data from our test dataset—because just validation is not enough! We have also built a nifty utility module called **model_evaluation_utils** , which we can use to evaluate the performance of our deep learning models with relevant classification metrics. The first step is to scale our test data.
|
||||
|
||||
|
||||
```
|
||||
test_imgs_scaled = test_data / 255.
|
||||
test_imgs_scaled.shape, test_labels.shape
|
||||
|
||||
# Output
|
||||
((8268, 125, 125, 3), (8268,))
|
||||
```
|
||||
|
||||
The next step involves loading our saved deep learning models and making predictions on the test data.
|
||||
|
||||
|
||||
```
|
||||
# Load Saved Deep Learning Models
|
||||
basic_cnn = tf.keras.models.load_model('./basic_cnn.h5')
|
||||
vgg_frz = tf.keras.models.load_model('./vgg_frozen.h5')
|
||||
vgg_ft = tf.keras.models.load_model('./vgg_finetuned.h5')
|
||||
|
||||
# Make Predictions on Test Data
|
||||
basic_cnn_preds = basic_cnn.predict(test_imgs_scaled, batch_size=512)
|
||||
vgg_frz_preds = vgg_frz.predict(test_imgs_scaled, batch_size=512)
|
||||
vgg_ft_preds = vgg_ft.predict(test_imgs_scaled, batch_size=512)
|
||||
|
||||
basic_cnn_pred_labels = le.inverse_transform([1 if pred > 0.5 else 0
|
||||
for pred in basic_cnn_preds.ravel()])
|
||||
vgg_frz_pred_labels = le.inverse_transform([1 if pred > 0.5 else 0
|
||||
for pred in vgg_frz_preds.ravel()])
|
||||
vgg_ft_pred_labels = le.inverse_transform([1 if pred > 0.5 else 0
|
||||
for pred in vgg_ft_preds.ravel()])
|
||||
```
|
||||
|
||||
The final step is to leverage our **model_evaluation_utils** module and check the performance of each model with relevant classification metrics.
|
||||
|
||||
|
||||
```
|
||||
import model_evaluation_utils as meu
|
||||
import pandas as pd
|
||||
|
||||
basic_cnn_metrics = meu.get_metrics(true_labels=test_labels, predicted_labels=basic_cnn_pred_labels)
|
||||
vgg_frz_metrics = meu.get_metrics(true_labels=test_labels, predicted_labels=vgg_frz_pred_labels)
|
||||
vgg_ft_metrics = meu.get_metrics(true_labels=test_labels, predicted_labels=vgg_ft_pred_labels)
|
||||
|
||||
pd.DataFrame([basic_cnn_metrics, vgg_frz_metrics, vgg_ft_metrics],
|
||||
index=['Basic CNN', 'VGG-19 Frozen', 'VGG-19 Fine-tuned'])
|
||||
```
|
||||
|
||||
![Model accuracy][28]
|
||||
|
||||
It looks like our third model performs best on the test dataset, giving a model accuracy and an F1-score of 96%, which is pretty good and quite comparable to the more complex models mentioned in the research paper and articles we mentioned earlier.
|
||||
|
||||
### Conclusion
|
||||
|
||||
Malaria detection is not an easy procedure, and the availability of qualified personnel around the globe is a serious concern in the diagnosis and treatment of cases. We looked at an interesting real-world medical imaging case study of malaria detection. Easy-to-build, open source techniques leveraging AI can give us state-of-the-art accuracy in detecting malaria, thus enabling AI for social good.
|
||||
|
||||
I encourage you to check out the articles and research papers mentioned in this article, without which it would have been impossible for me to conceptualize and write it. If you are interested in running or adopting these techniques, all the code used in this article is available on [my GitHub repository][24]. Remember to download the data from the [official website][11].
|
||||
|
||||
Let's hope for more adoption of open source AI capabilities in healthcare to make it less expensive and more accessible for everyone around the world!
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/19/4/detecting-malaria-deep-learning
|
||||
|
||||
作者：[Dipanjan (DJ) Sarkar (Red Hat)][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://opensource.com/users/djsarkar
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/osdc_520x292_opensourcedoctor.png?itok=fk79NwpC
|
||||
[2]: https://opensource.com/sites/default/files/uploads/malaria1_python-tensorflow.png (Python and TensorFlow)
|
||||
[3]: https://opensource.com/sites/default/files/uploads/malaria2_malaria-heat-map.png (Malaria heat map)
|
||||
[4]: https://www.who.int/features/factfiles/malaria/en/
|
||||
[5]: https://peerj.com/articles/4568/
|
||||
[6]: https://blog.insightdatascience.com/https-blog-insightdatascience-com-malaria-hero-a47d3d5fc4bb
|
||||
[7]: https://www.pyimagesearch.com/2018/12/03/deep-learning-and-medical-image-analysis-with-keras/
|
||||
[8]: https://opensource.com/sites/default/files/uploads/malaria3_blood-smear.png (Blood smear workflow for Malaria detection)
|
||||
[9]: http://cs231n.github.io/convolutional-networks/
|
||||
[10]: https://opensource.com/sites/default/files/uploads/malaria4_cnn-architecture.png (A typical CNN architecture)
|
||||
[11]: https://ceb.nlm.nih.gov/repositories/malaria-datasets/
|
||||
[12]: https://www.ncbi.nlm.nih.gov/pubmed/29360430
|
||||
[13]: https://opensource.com/sites/default/files/uploads/malaria5_dependencies.png (Installing dependencies)
|
||||
[14]: https://opensource.com/sites/default/files/uploads/malaria6_tree-dependency.png (Installing the tree dependency)
|
||||
[15]: https://opensource.com/sites/default/files/uploads/malaria7_dataset.png (Datasets)
|
||||
[16]: https://opensource.com/sites/default/files/uploads/malaria8_cell-samples.png (Malaria cell samples)
|
||||
[17]: https://opensource.com/sites/default/files/uploads/malaria9_learningcurves.png (Learning curves for basic CNN)
|
||||
[18]: https://towardsdatascience.com/a-comprehensive-hands-on-guide-to-transfer-learning-with-real-world-applications-in-deep-learning-212bf3b2f27a
|
||||
[19]: https://github.com/dipanjanS/hands-on-transfer-learning-with-python
|
||||
[20]: https://opensource.com/sites/default/files/uploads/malaria10_transferideas.png (Ideas for deep transfer learning)
|
||||
[21]: http://image-net.org/index
|
||||
[22]: https://arxiv.org/pdf/1409.1556.pdf
|
||||
[23]: https://opensource.com/sites/default/files/uploads/malaria11_vgg-19-model-architecture.png (VGG-19 Model Architecture)
|
||||
[24]: https://nbviewer.jupyter.org/github/dipanjanS/data_science_for_all/tree/master/os_malaria_detection/
|
||||
[25]: https://opensource.com/sites/default/files/uploads/malaria12_learningcurves.png (Learning curves for frozen pre-trained CNN)
|
||||
[26]: https://opensource.com/sites/default/files/uploads/malaria13_sampleimages.png (Sample augmented images)
|
||||
[27]: https://opensource.com/sites/default/files/uploads/malaria14_learningcurves.png (Learning curves for fine-tuned pre-trained CNN)
|
||||
[28]: https://opensource.com/sites/default/files/uploads/malaria15_modelaccuracy.png (Model accuracy)
|
||||
238
sources/tech/20190416 How to Install MySQL in Ubuntu Linux.md
Normal file
238
sources/tech/20190416 How to Install MySQL in Ubuntu Linux.md
Normal file
@@ -0,0 +1,238 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (How to Install MySQL in Ubuntu Linux)
|
||||
[#]: via: (https://itsfoss.com/install-mysql-ubuntu/)
|
||||
[#]: author: (Sergiu https://itsfoss.com/author/sergiu/)
|
||||
|
||||
How to Install MySQL in Ubuntu Linux
|
||||
======
|
||||
|
||||
_**Brief: This tutorial teaches you to install MySQL in Ubuntu based Linux distributions. You’ll also learn how to verify your install and how to connect to MySQL for the first time.**_
|
||||
|
||||
**[MySQL][1]** is the quintessential database management system. It is used in many tech stacks, including the popular **[LAMP][2]** (Linux, Apache, MySQL, PHP) stack. It has proven its stability. Another thing that makes **MySQL** so great is that it is **open-source**.
|
||||
|
||||
**MySQL** uses **relational databases** (basically **tabular data** ). It is really easy to store, organize and access data this way. For managing data, **SQL** ( **Structured Query Language** ) is used.
|
||||
|
||||
In this article I’ll show you how to **install** and **use** MySQL 8.0 in Ubuntu 18.04. Let’s get to it!
|
||||
|
||||
### Installing MySQL in Ubuntu
|
||||
|
||||
![][3]
|
||||
|
||||
I’ll be covering two ways you can install **MySQL** in Ubuntu 18.04:
|
||||
|
||||
1. Install MySQL from the Ubuntu repositories. Very basic, not the latest version (5.7)
|
||||
2. Install MySQL using the official repository. There is a bigger step that you’ll have to add to the process, but nothing to worry about. Also, you’ll have the latest version (8.0)
|
||||
|
||||
|
||||
|
||||
When needed, I’ll provide screenshots to guide you. For most of this guide, I’ll be entering commands in the **terminal** ( **default hotkey** : CTRL+ALT+T). Don’t be scared of it!
|
||||
|
||||
#### Method 1. Installing MySQL from the Ubuntu repositories
|
||||
|
||||
First of all, make sure your repositories are updated by entering:
|
||||
|
||||
```
|
||||
sudo apt update
|
||||
```
|
||||
|
||||
Now, to install **MySQL 5.7** , simply type:
|
||||
|
||||
```
|
||||
sudo apt install mysql-server -y
|
||||
```
|
||||
|
||||
That’s it! Simple and efficient.
|
||||
|
||||
#### Method 2. Installing MySQL using the official repository
|
||||
|
||||
Although this method has a few more steps, I’ll go through them one by one and I’ll try writing down clear notes.
|
||||
|
||||
The first step is browsing to the [download page][4] of the official MySQL website.
|
||||
|
||||
![][5]
|
||||
|
||||
Here, go down to the **download link** for the **DEB Package**.
|
||||
|
||||
![][6]
|
||||
|
||||
Scroll down past the info about Oracle Web and right-click on **No thanks, just start my download.** Select **Copy link location**.
|
||||
|
||||
Now go back to the terminal. We’ll [use][7] **[Curl][7]** [command][7] to the download the package:
|
||||
|
||||
```
|
||||
curl -OL https://dev.mysql.com/get/mysql-apt-config_0.8.12-1_all.deb
|
||||
```
|
||||
|
||||
**<https://dev.mysql.com/get/mysql-apt-config\_0.8.12-1\_all.deb>** is the link I copied from the website. It might be different based on the current version of MySQL. Let’s use **dpkg** to start installing MySQL:
|
||||
|
||||
```
|
||||
sudo dpkg -i mysql-apt-config*
|
||||
```
|
||||
|
||||
Update your repositories:
|
||||
|
||||
```
|
||||
sudo apt update
|
||||
```
|
||||
|
||||
To actually install MySQL, we’ll use the same command as in the first method:
|
||||
|
||||
```
|
||||
sudo apt install mysql-server -y
|
||||
```
|
||||
|
||||
Doing so will open a prompt in your terminal for **package configuration**. Use the **down arrow** to select the **Ok** option.
|
||||
|
||||
![][8]
|
||||
|
||||
Press **Enter**. This should prompt you to enter a **password** :. Your are basically setting the root password for MySQL. Don’t confuse it with [root password of Ubuntu][9] system.
|
||||
|
||||
![][10]
|
||||
|
||||
Type in a password and press **Tab** to select **< Ok>**. Press **Enter.** You’ll now have to **re-enter** the **password**. After doing so, press **Tab** again to select **< Ok>**. Press **Enter**.
|
||||
|
||||
![][11]
|
||||
|
||||
Some **information** on configuring MySQL Server will be presented. Press **Tab** to select **< Ok>** and **Enter** again:
|
||||
|
||||
![][12]
|
||||
|
||||
Here you need to choose a **default authentication plugin**. Make sure **Use Strong Password Encryption** is selected. Press **Tab** and then **Enter**.
|
||||
|
||||
That’s it! You have successfully installed MySQL.
|
||||
|
||||
#### Verify your MySQL installation
|
||||
|
||||
To **verify** that MySQL installed correctly, use:
|
||||
|
||||
```
|
||||
sudo systemctl status mysql.service
|
||||
```
|
||||
|
||||
This will show some information about the service:
|
||||
|
||||
![][13]
|
||||
|
||||
You should see **Active: active (running)** in there somewhere. If you don’t, use the following command to start the **service** :
|
||||
|
||||
```
|
||||
sudo systemctl start mysql.service
|
||||
```
|
||||
|
||||
#### Configuring/Securing MySQL
|
||||
|
||||
For a new install, you should run the provided command for security-related updates. That’s:
|
||||
|
||||
```
|
||||
sudo mysql_secure_installation
|
||||
```
|
||||
|
||||
Doing so will first of all ask you if you want to use the **VALIDATE PASSWORD COMPONENT**. If you want to use it, you’ll have to select a minimum password strength ( **0 – Low, 1 – Medium, 2 – High** ). You won’t be able to input any password doesn’t respect the selected rules. If you don’t have the habit of using strong passwords (you should!), this could come in handy. If you think it might help, type in **y** or **Y** and press **Enter** , then choose a **strength level** for your password and input the one you want to use. If successful, you’ll continue the **securing** process; otherwise you’ll have to re-enter a password.
|
||||
|
||||
If, however, you do not want this feature (I won’t), just press **Enter** or **any other key** to skip using it.
|
||||
|
||||
For the other options, I suggest **enabling** them (typing in **y** or **Y** and pressing **Enter** for each of them). They are (in this order): **remove anonymous user, disallow root login remotely, remove test database and access to it, reload privilege tables now**.
|
||||
|
||||
#### Connecting to & Disconnecting from the MySQL Server
|
||||
|
||||
To be able to run SQL queries, you’ll first have to connect to the server using MySQL and use the MySQL prompt. The command for doing this is:
|
||||
|
||||
```
|
||||
mysql -h host_name -u user -p
|
||||
```
|
||||
|
||||
* **-h** is used to specify a **host name** (if the server is located on another machine; if it isn’t, just omit it)
|
||||
* **-u** mentions the **user**
|
||||
* **-p** specifies that you want to input a **password**.
|
||||
|
||||
|
||||
|
||||
Although not recommended (for safety reasons), you can enter the password directly in the command by typing it in right after **-p**. For example, if the password for **test_user** is **1234** and you are trying to connect on the machine you are using, you could use:
|
||||
|
||||
```
|
||||
mysql -u test_user -p1234
|
||||
```
|
||||
|
||||
If you successfully inputted the required parameters, you’ll be greeted by the **MySQL shell prompt** ( **mysql >**):
|
||||
|
||||
![][14]
|
||||
|
||||
To **disconnect** from the server and **leave** the mysql prompt, type:
|
||||
|
||||
```
|
||||
QUIT
|
||||
```
|
||||
|
||||
Typing **quit** (MySQL is case insensitive) or **\q** will also work. Press **Enter** to exit.
|
||||
|
||||
You can also output info about the **version** with a simple command:
|
||||
|
||||
```
|
||||
sudo mysqladmin -u root version -p
|
||||
```
|
||||
|
||||
If you want to see a **list of options** , use:
|
||||
|
||||
```
|
||||
mysql --help
|
||||
```
|
||||
|
||||
#### Uninstalling MySQL
|
||||
|
||||
If you decide that you want to use a newer release or just want to stop using MySQL.
|
||||
|
||||
First, disable the service:
|
||||
|
||||
```
|
||||
sudo systemctl stop mysql.service && sudo systemctl disable mysql.service
|
||||
```
|
||||
|
||||
Make sure you backed up your databases, in case you want to use them later on. You can uninstall MySQL by running:
|
||||
|
||||
```
|
||||
sudo apt purge mysql*
|
||||
```
|
||||
|
||||
To clean up dependecies:
|
||||
|
||||
```
|
||||
sudo apt autoremove
|
||||
```
|
||||
|
||||
**Wrapping Up**
|
||||
|
||||
In this article, I’ve covered **installing MySQL** in Ubuntu Linux. I’d be glad if this guide helps struggling users and beginners.
|
||||
|
||||
Tell us in the comments if you found this post to be a useful resource. What do you use MySQL for? We’re eager to receive any feedback, impressions or suggestions. Thanks for reading and have don’t hesitate to experiment with this incredible tool!
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://itsfoss.com/install-mysql-ubuntu/
|
||||
|
||||
作者：[Sergiu][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://itsfoss.com/author/sergiu/
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://www.mysql.com/
|
||||
[2]: https://en.wikipedia.org/wiki/LAMP_(software_bundle)
|
||||
[3]: https://i2.wp.com/itsfoss.com/wp-content/uploads/2019/04/install-mysql-ubuntu.png?resize=800%2C450&ssl=1
|
||||
[4]: https://dev.mysql.com/downloads/repo/apt/
|
||||
[5]: https://i0.wp.com/itsfoss.com/wp-content/uploads/2019/04/mysql_apt_download_page.jpg?fit=800%2C280&ssl=1
|
||||
[6]: https://i0.wp.com/itsfoss.com/wp-content/uploads/2019/04/mysql_deb_download_link.jpg?fit=800%2C507&ssl=1
|
||||
[7]: https://linuxhandbook.com/curl-command-examples/
|
||||
[8]: https://i1.wp.com/itsfoss.com/wp-content/uploads/2019/04/mysql_package_configuration_ok.jpg?fit=800%2C587&ssl=1
|
||||
[9]: https://itsfoss.com/change-password-ubuntu/
|
||||
[10]: https://i2.wp.com/itsfoss.com/wp-content/uploads/2019/04/mysql_enter_password.jpg?fit=800%2C583&ssl=1
|
||||
[11]: https://i0.wp.com/itsfoss.com/wp-content/uploads/2019/04/mysql_information_on_configuring.jpg?fit=800%2C581&ssl=1
|
||||
[12]: https://i2.wp.com/itsfoss.com/wp-content/uploads/2019/04/mysql_default_authentication_plugin.jpg?fit=800%2C586&ssl=1
|
||||
[13]: https://i1.wp.com/itsfoss.com/wp-content/uploads/2019/04/mysql_service_information.jpg?fit=800%2C402&ssl=1
|
||||
[14]: https://i2.wp.com/itsfoss.com/wp-content/uploads/2019/04/mysql_shell_prompt-2.jpg?fit=800%2C423&ssl=1
|
||||
@@ -0,0 +1,531 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (Inter-process communication in Linux: Using pipes and message queues)
|
||||
[#]: via: (https://opensource.com/article/19/4/interprocess-communication-linux-channels)
|
||||
[#]: author: (Marty Kalin https://opensource.com/users/mkalindepauledu)
|
||||
|
||||
Inter-process communication in Linux: Using pipes and message queues
|
||||
======
|
||||
Learn how processes synchronize with each other in Linux.
|
||||
![Chat bubbles][1]
|
||||
|
||||
This is the second article in a series about [interprocess communication][2] (IPC) in Linux. The [first article][3] focused on IPC through shared storage: shared files and shared memory segments. This article turns to pipes, which are channels that connect processes for communication. A channel has a _write end_ for writing bytes, and a _read end_ for reading these bytes in FIFO (first in, first out) order. In typical use, one process writes to the channel, and a different process reads from this same channel. The bytes themselves might represent anything: numbers, employee records, digital movies, and so on.
|
||||
|
||||
Pipes come in two flavors, named and unnamed, and can be used either interactively from the command line or within programs; examples are forthcoming. This article also looks at memory queues, which have fallen out of fashion—but undeservedly so.
|
||||
|
||||
The code examples in the first article acknowledged the threat of race conditions (either file-based or memory-based) in IPC that uses shared storage. The question naturally arises about safe concurrency for the channel-based IPC, which will be covered in this article. The code examples for pipes and memory queues use APIs with the POSIX stamp of approval, and a core goal of the POSIX standards is thread-safety.
|
||||
|
||||
Consider the [man pages for the **mq_open**][4] function, which belongs to the memory queue API. These pages include a section on [Attributes][5] with this small table:
|
||||
|
||||
Interface | Attribute | Value
|
||||
---|---|---
|
||||
mq_open() | Thread safety | MT-Safe
|
||||
|
||||
The value **MT-Safe** (with **MT** for multi-threaded) means that the **mq_open** function is thread-safe, which in turn implies process-safe: A process executes in precisely the sense that one of its threads executes, and if a race condition cannot arise among threads in the _same_ process, such a condition cannot arise among threads in different processes. The **MT-Safe** attribute assures that a race condition does not arise in invocations of **mq_open**. In general, channel-based IPC is concurrent-safe, although a cautionary note is raised in the examples that follow.
|
||||
|
||||
### Unnamed pipes
|
||||
|
||||
Let's start with a contrived command line example that shows how unnamed pipes work. On all modern systems, the vertical bar **|** represents an unnamed pipe at the command line. Assume **%** is the command line prompt, and consider this command:
|
||||
|
||||
|
||||
```
|
||||
`% sleep 5 | echo "Hello, world!" ## writer to the left of |, reader to the right`
|
||||
```
|
||||
|
||||
The _sleep_ and _echo_ utilities execute as separate processes, and the unnamed pipe allows them to communicate. However, the example is contrived in that no communication occurs. The greeting _Hello, world!_ appears on the screen; then, after about five seconds, the command line prompt returns, indicating that both the _sleep_ and _echo_ processes have exited. What's going on?
|
||||
|
||||
In the vertical-bar syntax from the command line, the process to the left ( _sleep_ ) is the writer, and the process to the right ( _echo_ ) is the reader. By default, the reader blocks until there are bytes to read from the channel, and the writer—after writing its bytes—finishes up by sending an end-of-stream marker. (Even if the writer terminates prematurely, an end-of-stream marker is sent to the reader.) The unnamed pipe persists until both the writer and the reader terminate.
|
||||
|
||||
In the contrived example, the _sleep_ process does not write any bytes to the channel but does terminate after about five seconds, which sends an end-of-stream marker to the channel. In the meantime, the _echo_ process immediately writes the greeting to the standard output (the screen) because this process does not read any bytes from the channel, so it does no waiting. Once the _sleep_ and _echo_ processes terminate, the unnamed pipe—not used at all for communication—goes away and the command line prompt returns.
|
||||
|
||||
Here is a more useful example using two unnamed pipes. Suppose that the file _test.dat_ looks like this:
|
||||
|
||||
|
||||
```
|
||||
this
|
||||
is
|
||||
the
|
||||
way
|
||||
the
|
||||
world
|
||||
ends
|
||||
```
|
||||
|
||||
The command:
|
||||
|
||||
|
||||
```
|
||||
`% cat test.dat | sort | uniq`
|
||||
```
|
||||
|
||||
pipes the output from the _cat_ (concatenate) process into the _sort_ process to produce sorted output, and then pipes the sorted output into the _uniq_ process to eliminate duplicate records (in this case, the two occurrences of **the** reduce to one):
|
||||
|
||||
|
||||
```
|
||||
ends
|
||||
is
|
||||
the
|
||||
this
|
||||
way
|
||||
world
|
||||
```
|
||||
|
||||
The scene now is set for a program with two processes that communicate through an unnamed pipe.
|
||||
|
||||
#### Example 1. Two processes communicating through an unnamed pipe.
|
||||
|
||||
|
||||
```
|
||||
#include <sys/wait.h> /* wait */
|
||||
#include <stdio.h>
|
||||
#include <stdlib.h> /* exit functions */
|
||||
#include <unistd.h> /* read, write, pipe, _exit */
|
||||
#include <string.h>
|
||||
|
||||
#define ReadEnd 0
|
||||
#define WriteEnd 1
|
||||
|
||||
void report_and_exit(const char* msg) {
|
||||
[perror][6](msg);
|
||||
[exit][7](-1); /** failure **/
|
||||
}
|
||||
|
||||
int main() {
|
||||
int pipeFDs[2]; /* two file descriptors */
|
||||
char buf; /* 1-byte buffer */
|
||||
const char* msg = "Nature's first green is gold\n"; /* bytes to write */
|
||||
|
||||
if (pipe(pipeFDs) < 0) report_and_exit("pipeFD");
|
||||
pid_t cpid = fork(); /* fork a child process */
|
||||
if (cpid < 0) report_and_exit("fork"); /* check for failure */
|
||||
|
||||
if (0 == cpid) { /*** child ***/ /* child process */
|
||||
close(pipeFDs[WriteEnd]); /* child reads, doesn't write */
|
||||
|
||||
while (read(pipeFDs[ReadEnd], &buf, 1) > 0) /* read until end of byte stream */
|
||||
write(STDOUT_FILENO, &buf, sizeof(buf)); /* echo to the standard output */
|
||||
|
||||
close(pipeFDs[ReadEnd]); /* close the ReadEnd: all done */
|
||||
_exit(0); /* exit and notify parent at once */
|
||||
}
|
||||
else { /*** parent ***/
|
||||
close(pipeFDs[ReadEnd]); /* parent writes, doesn't read */
|
||||
|
||||
write(pipeFDs[WriteEnd], msg, [strlen][8](msg)); /* write the bytes to the pipe */
|
||||
close(pipeFDs[WriteEnd]); /* done writing: generate eof */
|
||||
|
||||
wait(NULL); /* wait for child to exit */
|
||||
[exit][7](0); /* exit normally */
|
||||
}
|
||||
return 0;
|
||||
}
|
||||
```
|
||||
|
||||
The _pipeUN_ program above uses the system function **fork** to create a process. Although the program has but a single source file, multi-processing occurs during (successful) execution. Here are the particulars in a quick review of how the library function **fork** works:
|
||||
|
||||
* The **fork** function, called in the _parent_ process, returns **-1** to the parent in case of failure. In the _pipeUN_ example, the call is: [code]`pid_t cpid = fork(); /* called in parent */`[/code] The returned value is stored, in this example, in the variable **cpid** of integer type **pid_t**. (Every process has its own _process ID_ , a non-negative integer that identifies the process.) Forking a new process could fail for several reasons, including a full _process table_ , a structure that the system maintains to track processes. Zombie processes, clarified shortly, can cause a process table to fill if these are not harvested.
|
||||
* If the **fork** call succeeds, it thereby spawns (creates) a new child process, returning one value to the parent but a different value to the child. Both the parent and the child process execute the _same_ code that follows the call to **fork**. (The child inherits copies of all the variables declared so far in the parent.) In particular, a successful call to **fork** returns:
|
||||
* Zero to the child process
|
||||
* The child's process ID to the parent
|
||||
* An _if/else_ or equivalent construct typically is used after a successful **fork** call to segregate code meant for the parent from code meant for the child. In this example, the construct is: [code] if (0 == cpid) { /*** child ***/
|
||||
...
|
||||
}
|
||||
else { /*** parent ***/
|
||||
...
|
||||
}
|
||||
```
|
||||
If forking a child succeeds, the _pipeUN_ program proceeds as follows. There is an integer array:
|
||||
```
|
||||
`int pipeFDs[2]; /* two file descriptors */`
|
||||
```
|
||||
to hold two file descriptors, one for writing to the pipe and another for reading from the pipe. (The array element **pipeFDs[0]** is the file descriptor for the read end, and the array element **pipeFDs[1]** is the file descriptor for the write end.) A successful call to the system **pipe** function, made immediately before the call to **fork** , populates the array with the two file descriptors:
|
||||
```
|
||||
`if (pipe(pipeFDs) < 0) report_and_exit("pipeFD");`
|
||||
```
|
||||
The parent and the child now have copies of both file descriptors, but the _separation of concerns_ pattern means that each process requires exactly one of the descriptors. In this example, the parent does the writing and the child does the reading, although the roles could be reversed. The first statement in the child _if_ -clause code, therefore, closes the pipe's write end:
|
||||
```
|
||||
`close(pipeFDs[WriteEnd]); /* called in child code */`
|
||||
```
|
||||
and the first statement in the parent _else_ -clause code closes the pipe's read end:
|
||||
```
|
||||
`close(pipeFDs[ReadEnd]); /* called in parent code */`
|
||||
```
|
||||
The parent then writes some bytes (ASCII codes) to the unnamed pipe, and the child reads these and echoes them to the standard output.
|
||||
|
||||
One more aspect of the program needs clarification: the call to the **wait** function in the parent code. Once spawned, a child process is largely independent of its parent, as even the short _pipeUN_ program illustrates. The child can execute arbitrary code that may have nothing to do with the parent. However, the system does notify the parent through a signal—if and when the child terminates.
|
||||
|
||||
What if the parent terminates before the child? In this case, unless precautions are taken, the child becomes and remains a _zombie_ process with an entry in the process table. The precautions are of two broad types. One precaution is to have the parent notify the system that the parent has no interest in the child's termination:
|
||||
```
|
||||
`signal(SIGCHLD, SIG_IGN); /* in parent: ignore notification */`
|
||||
```
|
||||
A second approach is to have the parent execute a **wait** on the child's termination, thereby ensuring that the parent outlives the child. This second approach is used in the _pipeUN_ program, where the parent code has this call:
|
||||
```
|
||||
`wait(NULL); /* called in parent */`
|
||||
```
|
||||
This call to **wait** means _wait until the termination of any child occurs_ , and in the _pipeUN_ program, there is only one child process. (The **NULL** argument could be replaced with the address of an integer variable to hold the child's exit status.) There is a more flexible **waitpid** function for fine-grained control, e.g., for specifying a particular child process among several.
|
||||
|
||||
The _pipeUN_ program takes another precaution. When the parent is done waiting, the parent terminates with the call to the regular **exit** function. By contrast, the child terminates with a call to the **_exit** variant, which fast-tracks notification of termination. In effect, the child is telling the system to notify the parent ASAP that the child has terminated.
|
||||
|
||||
If two processes write to the same unnamed pipe, can the bytes be interleaved? For example, if process P1 writes:
|
||||
```
|
||||
`foo bar`
|
||||
```
|
||||
to a pipe and process P2 concurrently writes:
|
||||
```
|
||||
`baz baz`
|
||||
```
|
||||
to the same pipe, it seems that the pipe contents might be something arbitrary, such as:
|
||||
```
|
||||
`baz foo baz bar`
|
||||
```
|
||||
The POSIX standard ensures that writes are not interleaved so long as no write exceeds **PIPE_BUF** bytes. On Linux systems, **PIPE_BUF** is 4,096 bytes in size. My preference with pipes is to have a single writer and a single reader, thereby sidestepping the issue.
|
||||
|
||||
## Named pipes
|
||||
|
||||
An unnamed pipe has no backing file: the system maintains an in-memory buffer to transfer bytes from the writer to the reader. Once the writer and reader terminate, the buffer is reclaimed, so the unnamed pipe goes away. By contrast, a named pipe has a backing file and a distinct API.
|
||||
|
||||
Let's look at another command line example to get the gist of named pipes. Here are the steps:
|
||||
|
||||
* Open two terminals. The working directory should be the same for both.
|
||||
* In one of the terminals, enter these two commands (the prompt again is **%** , and my comments start with **##** ): [code] % mkfifo tester ## creates a backing file named tester
|
||||
% cat tester ## type the pipe's contents to stdout [/code] At the beginning, nothing should appear in the terminal because nothing has been written yet to the named pipe.
|
||||
* In the second terminal, enter the command: [code] % cat > tester ## redirect keyboard input to the pipe
|
||||
hello, world! ## then hit Return key
|
||||
bye, bye ## ditto
|
||||
<Control-C> ## terminate session with a Control-C [/code] Whatever is typed into this terminal is echoed in the other. Once **Ctrl+C** is entered, the regular command line prompt returns in both terminals: the pipe has been closed.
|
||||
* Clean up by removing the file that implements the named pipe: [code]`% unlink tester`
|
||||
```
|
||||
|
||||
|
||||
|
||||
As the utility's name _mkfifo_ implies, a named pipe also is called a FIFO because the first byte in is the first byte out, and so on. There is a library function named **mkfifo** that creates a named pipe in programs and is used in the next example, which consists of two processes: one writes to the named pipe and the other reads from this pipe.
|
||||
|
||||
#### Example 2. The _fifoWriter_ program
|
||||
|
||||
|
||||
```
|
||||
#include <sys/types.h>
|
||||
#include <sys/stat.h>
|
||||
#include <fcntl.h>
|
||||
#include <unistd.h>
|
||||
#include <time.h>
|
||||
#include <stdlib.h>
|
||||
#include <stdio.h>
|
||||
|
||||
#define MaxLoops 12000 /* outer loop */
|
||||
#define ChunkSize 16 /* how many written at a time */
|
||||
#define IntsPerChunk 4 /* four 4-byte ints per chunk */
|
||||
#define MaxZs 250 /* max microseconds to sleep */
|
||||
|
||||
int main() {
|
||||
const char* pipeName = "./fifoChannel";
|
||||
mkfifo(pipeName, 0666); /* read/write for user/group/others */
|
||||
int fd = open(pipeName, O_CREAT | O_WRONLY); /* open as write-only */
|
||||
if (fd < 0) return -1; /* can't go on */
|
||||
|
||||
int i;
|
||||
for (i = 0; i < MaxLoops; i++) { /* write MaxWrites times */
|
||||
int j;
|
||||
for (j = 0; j < ChunkSize; j++) { /* each time, write ChunkSize bytes */
|
||||
int k;
|
||||
int chunk[IntsPerChunk];
|
||||
for (k = 0; k < IntsPerChunk; k++)
|
||||
chunk[k] = [rand][9]();
|
||||
write(fd, chunk, sizeof(chunk));
|
||||
}
|
||||
usleep(([rand][9]() % MaxZs) + 1); /* pause a bit for realism */
|
||||
}
|
||||
|
||||
close(fd); /* close pipe: generates an end-of-stream marker */
|
||||
unlink(pipeName); /* unlink from the implementing file */
|
||||
[printf][10]("%i ints sent to the pipe.\n", MaxLoops * ChunkSize * IntsPerChunk);
|
||||
|
||||
return 0;
|
||||
}
|
||||
```
|
||||
|
||||
The _fifoWriter_ program above can be summarized as follows:
|
||||
|
||||
* The program creates a named pipe for writing: [code] mkfifo(pipeName, 0666); /* read/write perms for user/group/others */
|
||||
int fd = open(pipeName, O_CREAT | O_WRONLY); [/code] where **pipeName** is the name of the backing file passed to **mkfifo** as the first argument. The named pipe then is opened with the by-now familiar call to the **open** function, which returns a file descriptor.
|
||||
* For a touch of realism, the _fifoWriter_ does not write all the data at once, but instead writes a chunk, sleeps a random number of microseconds, and so on. In total, 768,000 4-byte integer values are written to the named pipe.
|
||||
* After closing the named pipe, the _fifoWriter_ also unlinks the file: [code] close(fd); /* close pipe: generates end-of-stream marker */
|
||||
unlink(pipeName); /* unlink from the implementing file */ [/code] The system reclaims the backing file once every process connected to the pipe has performed the unlink operation. In this example, there are only two such processes: the _fifoWriter_ and the _fifoReader_ , both of which do an _unlink_ operation.
|
||||
|
||||
|
||||
|
||||
The two programs should be executed in different terminals with the same working directory. However, the _fifoWriter_ should be started before the _fifoReader_ , as the former creates the pipe. The _fifoReader_ then accesses the already created named pipe.
|
||||
|
||||
#### Example 3. The _fifoReader_ program
|
||||
|
||||
|
||||
```
|
||||
#include <stdio.h>
|
||||
#include <stdlib.h>
|
||||
#include <string.h>
|
||||
#include <fcntl.h>
|
||||
#include <unistd.h>
|
||||
|
||||
unsigned is_prime(unsigned n) { /* not pretty, but efficient */
|
||||
if (n <= 3) return n > 1;
|
||||
if (0 == (n % 2) || 0 == (n % 3)) return 0;
|
||||
|
||||
unsigned i;
|
||||
for (i = 5; (i * i) <= n; i += 6)
|
||||
if (0 == (n % i) || 0 == (n % (i + 2))) return 0;
|
||||
|
||||
return 1; /* found a prime! */
|
||||
}
|
||||
|
||||
int main() {
|
||||
const char* file = "./fifoChannel";
|
||||
int fd = open(file, O_RDONLY);
|
||||
if (fd < 0) return -1; /* no point in continuing */
|
||||
unsigned count = 0, total = 0, primes_count = 0;
|
||||
|
||||
while (1) {
|
||||
int next;
|
||||
int i;
|
||||
|
||||
ssize_t count = read(fd, &next, sizeof(int));
|
||||
if (0 == count) break; /* end of stream */
|
||||
else if (count == sizeof(int)) { /* read a 4-byte int value */
|
||||
total++;
|
||||
if (is_prime(next)) primes_count++;
|
||||
}
|
||||
}
|
||||
|
||||
close(fd); /* close pipe from read end */
|
||||
unlink(file); /* unlink from the underlying file */
|
||||
[printf][10]("Received ints: %u, primes: %u\n", total, primes_count);
|
||||
|
||||
return 0;
|
||||
}
|
||||
```
|
||||
|
||||
The _fifoReader_ program above can be summarized as follows:
|
||||
|
||||
* Because the _fifoWriter_ creates the named pipe, the _fifoReader_ needs only the standard call **open** to access the pipe through the backing file: [code] const char* file = "./fifoChannel";
|
||||
int fd = open(file, O_RDONLY); [/code] The file opens as read-only.
|
||||
* The program then goes into a potentially infinite loop, trying to read a 4-byte chunk on each iteration. The **read** call: [code]`ssize_t count = read(fd, &next, sizeof(int));`[/code] returns 0 to indicate end-of-stream, in which case the _fifoReader_ breaks out of the loop, closes the named pipe, and unlinks the backing file before terminating.
|
||||
* After reading a 4-byte integer, the _fifoReader_ checks whether the number is a prime. This represents the business logic that a production-grade reader might perform on the received bytes. On a sample run, there were 37,682 primes among the 768,000 integers received.
|
||||
|
||||
|
||||
|
||||
On repeated sample runs, the _fifoReader_ successfully read all of the bytes that the _fifoWriter_ wrote. This is not surprising. The two processes execute on the same host, taking network issues out of the equation. Named pipes are a highly reliable and efficient IPC mechanism and, therefore, in wide use.
|
||||
|
||||
Here is the output from the two programs, each launched from a separate terminal but with the same working directory:
|
||||
|
||||
|
||||
```
|
||||
% ./fifoWriter
|
||||
768000 ints sent to the pipe.
|
||||
###
|
||||
% ./fifoReader
|
||||
Received ints: 768000, primes: 37682
|
||||
```
|
||||
|
||||
### Message queues
|
||||
|
||||
Pipes have strict FIFO behavior: the first byte written is the first byte read, the second byte written is the second byte read, and so forth. Message queues can behave in the same way but are flexible enough that byte chunks can be retrieved out of FIFO order.
|
||||
|
||||
As the name suggests, a message queue is a sequence of messages, each of which has two parts:
|
||||
|
||||
* The payload, which is an array of bytes ( **char** in C)
|
||||
* A type, given as a positive integer value; types categorize messages for flexible retrieval
|
||||
|
||||
|
||||
|
||||
Consider the following depiction of a message queue, with each message labeled with an integer type:
|
||||
|
||||
|
||||
```
|
||||
+-+ +-+ +-+ +-+
|
||||
sender--->|3|--->|2|--->|2|--->|1|--->receiver
|
||||
+-+ +-+ +-+ +-+
|
||||
```
|
||||
|
||||
Of the four messages shown, the one labeled 1 is at the front, i.e., closest to the receiver. Next come two messages with label 2, and finally, a message labeled 3 at the back. If strict FIFO behavior were in play, then the messages would be received in the order 1-2-2-3. However, the message queue allows other retrieval orders. For example, the messages could be retrieved by the receiver in the order 3-2-1-2.
|
||||
|
||||
The _mqueue_ example consists of two programs, the _sender_ that writes to the message queue and the _receiver_ that reads from this queue. Both programs include the header file _queue.h_ shown below:
|
||||
|
||||
#### Example 4. The header file _queue.h_
|
||||
|
||||
|
||||
```
|
||||
#define ProjectId 123
|
||||
#define PathName "queue.h" /* any existing, accessible file would do */
|
||||
#define MsgLen 4
|
||||
#define MsgCount 6
|
||||
|
||||
typedef struct {
|
||||
long type; /* must be of type long */
|
||||
char payload[MsgLen + 1]; /* bytes in the message */
|
||||
} queuedMessage;
|
||||
```
|
||||
|
||||
The header file defines a structure type named **queuedMessage** , with **payload** (byte array) and **type** (integer) fields. This file also defines symbolic constants (the **#define** statements), the first two of which are used to generate a key that, in turn, is used to get a message queue ID. The **ProjectId** can be any positive integer value, and the **PathName** must be an existing, accessible file—in this case, the file _queue.h_. The setup statements in both the _sender_ and the _receiver_ programs are:
|
||||
|
||||
|
||||
```
|
||||
key_t key = ftok(PathName, ProjectId); /* generate key */
|
||||
int qid = msgget(key, 0666 | IPC_CREAT); /* use key to get queue id */
|
||||
```
|
||||
|
||||
The ID **qid** is, in effect, the counterpart of a file descriptor for message queues.
|
||||
|
||||
#### Example 5. The message _sender_ program
|
||||
|
||||
|
||||
```
|
||||
#include <stdio.h>
|
||||
#include <sys/ipc.h>
|
||||
#include <sys/msg.h>
|
||||
#include <stdlib.h>
|
||||
#include <string.h>
|
||||
#include "queue.h"
|
||||
|
||||
void report_and_exit(const char* msg) {
|
||||
[perror][6](msg);
|
||||
[exit][7](-1); /* EXIT_FAILURE */
|
||||
}
|
||||
|
||||
int main() {
|
||||
key_t key = ftok(PathName, ProjectId);
|
||||
if (key < 0) report_and_exit("couldn't get key...");
|
||||
|
||||
int qid = msgget(key, 0666 | IPC_CREAT);
|
||||
if (qid < 0) report_and_exit("couldn't get queue id...");
|
||||
|
||||
char* payloads[] = {"msg1", "msg2", "msg3", "msg4", "msg5", "msg6"};
|
||||
int types[] = {1, 1, 2, 2, 3, 3}; /* each must be > 0 */
|
||||
int i;
|
||||
for (i = 0; i < MsgCount; i++) {
|
||||
/* build the message */
|
||||
queuedMessage msg;
|
||||
msg.type = types[i];
|
||||
[strcpy][11](msg.payload, payloads[i]);
|
||||
|
||||
/* send the message */
|
||||
msgsnd(qid, &msg, sizeof(msg), IPC_NOWAIT); /* don't block */
|
||||
[printf][10]("%s sent as type %i\n", msg.payload, (int) msg.type);
|
||||
}
|
||||
return 0;
|
||||
}
|
||||
```
|
||||
|
||||
The _sender_ program above sends out six messages, two each of a specified type: the first messages are of type 1, the next two of type 2, and the last two of type 3. The sending statement:
|
||||
|
||||
|
||||
```
|
||||
`msgsnd(qid, &msg, sizeof(msg), IPC_NOWAIT);`
|
||||
```
|
||||
|
||||
is configured to be non-blocking (the flag **IPC_NOWAIT** ) because the messages are so small. The only danger is that a full queue, unlikely in this example, would result in a sending failure. The _receiver_ program below also receives messages using the **IPC_NOWAIT** flag.
|
||||
|
||||
#### Example 6. The message _receiver_ program
|
||||
|
||||
|
||||
```
|
||||
#include <stdio.h>
|
||||
#include <sys/ipc.h>
|
||||
#include <sys/msg.h>
|
||||
#include <stdlib.h>
|
||||
#include "queue.h"
|
||||
|
||||
void report_and_exit(const char* msg) {
|
||||
[perror][6](msg);
|
||||
[exit][7](-1); /* EXIT_FAILURE */
|
||||
}
|
||||
|
||||
int main() {
|
||||
key_t key= ftok(PathName, ProjectId); /* key to identify the queue */
|
||||
if (key < 0) report_and_exit("key not gotten...");
|
||||
|
||||
int qid = msgget(key, 0666 | IPC_CREAT); /* access if created already */
|
||||
if (qid < 0) report_and_exit("no access to queue...");
|
||||
|
||||
int types[] = {3, 1, 2, 1, 3, 2}; /* different than in sender */
|
||||
int i;
|
||||
for (i = 0; i < MsgCount; i++) {
|
||||
queuedMessage msg; /* defined in queue.h */
|
||||
if (msgrcv(qid, &msg, sizeof(msg), types[i], MSG_NOERROR | IPC_NOWAIT) < 0)
|
||||
[puts][12]("msgrcv trouble...");
|
||||
[printf][10]("%s received as type %i\n", msg.payload, (int) msg.type);
|
||||
}
|
||||
|
||||
/** remove the queue **/
|
||||
if (msgctl(qid, IPC_RMID, NULL) < 0) /* NULL = 'no flags' */
|
||||
report_and_exit("trouble removing queue...");
|
||||
|
||||
return 0;
|
||||
}
|
||||
```
|
||||
|
||||
The _receiver_ program does not create the message queue, although the API suggests as much. In the _receiver_ , the call:
|
||||
|
||||
|
||||
```
|
||||
`int qid = msgget(key, 0666 | IPC_CREAT);`
|
||||
```
|
||||
|
||||
is misleading because of the **IPC_CREAT** flag, but this flag really means _create if needed, otherwise access_. The _sender_ program calls **msgsnd** to send messages, whereas the _receiver_ calls **msgrcv** to retrieve them. In this example, the _sender_ sends the messages in the order 1-1-2-2-3-3, but the _receiver_ then retrieves them in the order 3-1-2-1-3-2, showing that message queues are not bound to strict FIFO behavior:
|
||||
|
||||
|
||||
```
|
||||
% ./sender
|
||||
msg1 sent as type 1
|
||||
msg2 sent as type 1
|
||||
msg3 sent as type 2
|
||||
msg4 sent as type 2
|
||||
msg5 sent as type 3
|
||||
msg6 sent as type 3
|
||||
|
||||
% ./receiver
|
||||
msg5 received as type 3
|
||||
msg1 received as type 1
|
||||
msg3 received as type 2
|
||||
msg2 received as type 1
|
||||
msg6 received as type 3
|
||||
msg4 received as type 2
|
||||
```
|
||||
|
||||
The output above shows that the _sender_ and the _receiver_ can be launched from the same terminal. The output also shows that the message queue persists even after the _sender_ process creates the queue, writes to it, and exits. The queue goes away only after the _receiver_ process explicitly removes it with the call to **msgctl** :
|
||||
|
||||
|
||||
```
|
||||
`if (msgctl(qid, IPC_RMID, NULL) < 0) /* remove queue */`
|
||||
```
|
||||
|
||||
### Wrapping up
|
||||
|
||||
The pipes and message queue APIs are fundamentally _unidirectional_ : one process writes and another reads. There are implementations of bidirectional named pipes, but my two cents is that this IPC mechanism is at its best when it is simplest. As noted earlier, message queues have fallen in popularity—but without good reason; these queues are yet another tool in the IPC toolbox. Part 3 completes this quick tour of the IPC toolbox with code examples of IPC through sockets and signals.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/19/4/interprocess-communication-linux-channels
|
||||
|
||||
作者：[Marty Kalin][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://opensource.com/users/mkalindepauledu
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/talk_chat_communication_team.png?itok=CYfZ_gE7 (Chat bubbles)
|
||||
[2]: https://en.wikipedia.org/wiki/Inter-process_communication
|
||||
[3]: https://opensource.com/article/19/4/interprocess-communication-ipc-linux-part-1
|
||||
[4]: http://man7.org/linux/man-pages/man2/mq_open.2.html
|
||||
[5]: http://man7.org/linux/man-pages/man2/mq_open.2.html#ATTRIBUTES
|
||||
[6]: http://www.opengroup.org/onlinepubs/009695399/functions/perror.html
|
||||
[7]: http://www.opengroup.org/onlinepubs/009695399/functions/exit.html
|
||||
[8]: http://www.opengroup.org/onlinepubs/009695399/functions/strlen.html
|
||||
[9]: http://www.opengroup.org/onlinepubs/009695399/functions/rand.html
|
||||
[10]: http://www.opengroup.org/onlinepubs/009695399/functions/printf.html
|
||||
[11]: http://www.opengroup.org/onlinepubs/009695399/functions/strcpy.html
|
||||
[12]: http://www.opengroup.org/onlinepubs/009695399/functions/puts.html
|
||||
@@ -0,0 +1,68 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (Linux Foundation Training Courses Sale & Discount Coupon)
|
||||
[#]: via: (https://itsfoss.com/linux-foundation-discount-coupon/)
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||||
[#]: author: (Abhishek Prakash https://itsfoss.com/author/abhishek/)
|
||||
|
||||
Linux Foundation Training Courses Sale & Discount Coupon
|
||||
======
|
||||
|
||||
Linux Foundation is the non-profit organization that employs Linux creator Linus Torvalds and manages the development of the Linux kernel. Linux Foundation aims to promote the adoption of Linux and Open Source in the industry and it is doing a great job in this regard.
|
||||
|
||||
Open Source jobs are in demand and no one knows is better than Linux Foundation, the official Linux organization. This is why the Linux Foundation provides a number of training and certification courses on Linux related technology. You can browse the [entire course offering on Linux Foundations’ training webpage][1].
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||||
|
||||
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||||
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||||
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||||
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||||
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||||
|
||||
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||||
|
||||
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||||
|
||||
_Do note that this offer is valid till 22nd April 2019 only._
|
||||
|
||||
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||||
|
||||
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||||
|
||||
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||||
|
||||
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||||
|
||||
This article contains affiliate links. Please read our [affiliate policy][3].
|
||||
|
||||
#### Should you get certified?
|
||||
|
||||
![][4]
|
||||
|
||||
This is the question I have been asked regularly. Are Linux certifications worth it? The short answer is yes.
|
||||
|
||||
As per the [open source jobs report in 2018][5], over 80% of open source professionals said that certifications helped with their careers. Certifications enable you to demonstrate technical knowledge to potential employers and thus certifications make you more employable in general.
|
||||
|
||||
Almost half of the hiring managers said that employing certified open source professionals is a priority for them.
|
||||
|
||||
Certifications from a reputed authority like Linux Foundation, Red Hat, LPIC etc are particularly helpful when you are a fresh graduate or if you want to switch to a new domain in your career.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://itsfoss.com/linux-foundation-discount-coupon/
|
||||
|
||||
作者：[Abhishek Prakash][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://itsfoss.com/author/abhishek/
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://shareasale.com/u.cfm?d=507759&m=59485&u=747593&afftrack=
|
||||
[2]: http://shrsl.com/1k5ug
|
||||
[3]: https://itsfoss.com/affiliate-policy/
|
||||
[4]: https://i2.wp.com/itsfoss.com/wp-content/uploads/2018/07/linux-foundation-training-certification-discount.png?ssl=1
|
||||
[5]: https://www.linuxfoundation.org/publications/open-source-jobs-report-2018/
|
||||
@@ -0,0 +1,118 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (Linux Server Hardening Using Idempotency with Ansible: Part 3)
|
||||
[#]: via: (https://www.linux.com/blog/linux-server-hardening-using-idempotency-ansible-part-3)
|
||||
[#]: author: (Chris Binnie https://www.linux.com/users/chrisbinnie)
|
||||
|
||||
Linux Server Hardening Using Idempotency with Ansible: Part 3
|
||||
======
|
||||
|
||||
![][1]
|
||||
|
||||
[Creative Commons Zero][2]
|
||||
|
||||
In the previous articles, we introduced idempotency as a way to approach your server’s security posture and looked at some specific Ansible examples, including the kernel, system accounts, and IPtables. In this final article of the series, we’ll look at a few more server-hardening examples and talk a little more about how the idempotency playbook might be used.
|
||||
|
||||
#### **Time**
|
||||
|
||||
Due to its reduced functionality, and therefore attack surface, the preference amongst a number of OSs has been to introduce “chronyd” over “ntpd”. If you’re new to “chrony” then fret not. It’s still using the NTP (Network Time Protocol) that we all know and love but in a more secure fashion.
|
||||
|
||||
The first thing I do with Ansible within the “chrony.conf” file is alter the “bind address” and if my memory serves there’s also a “command port” option. These config options allow Chrony to only listen on the localhost. In other words you are still syncing as usual with other upstream time servers (just as NTP does) but no remote servers can query your time services; only your local machine has access.
|
||||
|
||||
There’s more information on the “bindcmdaddress 127.0.0.1” and “cmdport 0” on this Chrony page (<https://chrony.tuxfamily.org/faq.html>) under “2.5. How can I make chronyd more secure?” which you should read for clarity. This premise behind the comment on that page is a good idea: “you can disable the internet command sockets completely by adding cmdport 0 to the configuration file”.
|
||||
|
||||
Additionally I would also focus on securing the file permissions for Chrony and insist that the service starts as expected just like the syslog config above. Otherwise make sure that your time sources are sane, have a degree of redundancy with multiple sources set up and then copy the whole config file over using Ansible.
|
||||
|
||||
#### **Logging**
|
||||
|
||||
You can clearly affect the level of detail included in the logs from a number pieces of software on a server. Thinking back to what we’ve looked at in relation to syslog already you can also tweak that application’s config using Ansible to your needs and then use the example Ansible above in addition.
|
||||
|
||||
#### **PAM**
|
||||
|
||||
Apparently PAM (Pluggable Authentication Modules) has been a part of Linux since 1997. It is undeniably useful (a common use is that you can force SSH to use it for password logins, as per the SSH YAML file above). It is extensible, sophisticated and can perform useful functions such as preventing brute force attacks on password logins using a clever rate limiting system. The syntax varies a little between OSes but if you have the time then getting PAM working well (even if you’re only using SSH keys and not passwords for your logins) is a worthwhile effort. Attackers like their own users on a system with lots of usernames, something innocuous such as “webadmin” or similar might be easy to miss on a server, and PAM can help you out in this respect.
|
||||
|
||||
#### **Auditd**
|
||||
|
||||
We’ve looked at logging a little already but what about capturing every “system call” that a kernel makes. The Linux kernel is a super-busy component of any system and logging almost every single thing that a system does is an excellent way of providing post-event forensics. This article will hopefully shed some light on where to begin: <http://www.admin-magazine.com/Archive/2018/43/Auditing-Docker-Containers-in-a-DevOps-Environment>. Note the comments in that article about performance, there’s little point in paying extra for compute and disk IO resource because you’ve misconfigured your logging so spend some time getting it correct would be my advice.
|
||||
|
||||
For concerns over disk space I will usually change a few lines in the file “/etc/audit/auditd.conf” in order to prevent there firstly being too many log files created and secondly logs that grow very large without being rotated. This is also on the proviso that logs are being ingested upstream via another mechanism too. Clearly the files permissions and the service starting are also the basics you need to cover here too. Generally file permissions for auditd are tight as it’s a “root” oriented service so there’s less changes needed here generally.
|
||||
|
||||
#### **Filesystems**
|
||||
|
||||
With a little reading you can discover which filesystems that are made available to your OS by default. You should disable these (at the “modprode.d” file level) with Ansible to prevent weird and wonderful things being attached unwittingly to your servers. You are reducing the attack surface with this approach. The Ansible might look something like this below for example.
|
||||
|
||||
```
|
||||
name: Make sure filesystems which are not needed are forced as off
|
||||
|
||||
lineinfile: dest="/etcmodprobe.d/harden.conf" line='install squashfs /bin/true' state=present
|
||||
```
|
||||
|
||||
#### **SELinux**
|
||||
|
||||
The old, but sometimes avoided due to complexity, security favourite, SELinux, should be set to “enforcing” mode. Or, at the every least, set to log sensibly using “permissive” mode. Permissive mode will at least fill your auditd logs up with any correct rule matches nicely. In terms of what Ansible looks like it’s simple and is along these lines:
|
||||
|
||||
```
|
||||
name: Configure SElinux to be running in permissive mode
|
||||
|
||||
replace: path=”/etc/selinux/config” regexp='SELINUX=disabled' replace='SELINUX=permissive'
|
||||
```
|
||||
|
||||
#### **Packages**
|
||||
|
||||
Needless to say the compliance hardening playbook is also a good place to upgrade all the packages (with some selective exclusions) on the system. Pay attention to the section relating to reboots and idempotency in a moment however. With other mechanisms in place you might not want to update packages here but instead as per the Automation Documents article mentioned in a moment.
|
||||
|
||||
### **Idempotency**
|
||||
|
||||
Now we’ve run through some of the aspects you would want to look at when hardening on a server, let’s think a little more about how the playbook might be used.
|
||||
|
||||
When it comes to cloud platforms most of my professional work has been on AWS and therefore, more often than not, a fresh AMI is launched and then a playbook is run over the top of it. There’s a mountain of detail in one way of doing that in this article (<http://www.admin-magazine.com/Archive/2018/45/AWS-Automation-Documents>) which you may be pleased to discover accommodates a mechanism to spawn a script or playbook.
|
||||
|
||||
It is important to note, when it comes to idempotency, that it may take a little more effort initially to get your head around the logic involved in being able to re-run Ansible repeatedly without disturbing the required status quo of your server estate.
|
||||
|
||||
One thing to be absolutely certain of however (barring rare edge cases) is that after you apply your hardening for the very first time, on a new AMI or server build, you will require a reboot. This is an important element due to a number of system facets not being altered correctly without a reboot. These include applying kernel changes so alterations become live, writing auditd rules as immutable config and also starting or stopping services to improve the security posture.
|
||||
|
||||
Note though that you’re probably not going to want to execute all plays in a playbook every twenty or thirty minutes, such as updating all packages and stopping and restarting key customer-facing services. As a result you should factor the logic into your Ansible so that some tasks only run once initially and then maybe write a “completed” placeholder file to the filesystem afterwards for referencing. There’s a million different ways of achieving a status checker.
|
||||
|
||||
The nice thing about Ansible is that the logic for rerunning playbooks is implicit and unlike shell scripts which for this type of task can be arduous to code the logic into. Sometimes, such as updating the GRUB bootloader for example, trying to guess the many permutations of a system change can be painful.
|
||||
|
||||
### **Bedtime Reading**
|
||||
|
||||
I still think that you can’t beat trial and error when it comes to computing. Experience is valued for good reason.
|
||||
|
||||
Be warned that you’ll find contradictory advice sometimes from the vast array of online resources in this area. Advice differs probably because of the different use cases. The only way to harden the varying flavours of OS to my mind is via a bespoke approach. This is thanks to the environments that servers are used within and the requirements of the security framework or standard that an organisation needs to meet.
|
||||
|
||||
For OS hardening details you can check with resources such as the NSA ([https://www.nsa.gov][3]), the Cloud Security Alliance (<https://cloudsecurityalliance.org/working-groups/security-guidance/#_overview>), proprietary training organisations such as GIAC ([https://www.giac.org][4]) who offer resources (<https://www.giac.org/paper/gcux/97/red-hat-linux-71-installation-hardening-checklist/102167>), the diverse CIS Benchmarks ([https://www.cisecurity.org][5]) for industry consensus-based benchmarking, the SANS Institute (<https://uk.sans.org/score/checklists>), NIST’s Computer Security Research ([https://csrc.nist.gov][6]) and of course print media too.
|
||||
|
||||
### **Conclusion**
|
||||
|
||||
Hopefully, you can see how powerful an idempotent server infrastructure is and are tempted to try it for yourself.
|
||||
|
||||
The ever-present threat of APT (Advanced Persistent Threat) attacks on infrastructure, where a successful attacker will sit silently monitoring events and then when it’s opportune infiltrate deeper into an estate, makes this type of configuration highly valuable.
|
||||
|
||||
The amount of detail that goes into the tests and configuration changes is key to the value that such an approach will bring to an organisation. Like the tests in a CI/CD pipeline they’re only as ever as good as their coverage.
|
||||
|
||||
Chris Binnie’s latest book, Linux Server Security: Hack and Defend, shows you how to make your servers invisible and perform a variety of attacks. You can find out more about DevSecOps, containers and Linux security on his website: [https://www.devsecops.cc][7]
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.linux.com/blog/linux-server-hardening-using-idempotency-ansible-part-3
|
||||
|
||||
作者：[Chris Binnie][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://www.linux.com/users/chrisbinnie
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://www.linux.com/sites/lcom/files/styles/rendered_file/public/tech-1495181_1280.jpg?itok=5WcwApNN
|
||||
[2]: /LICENSES/CATEGORY/CREATIVE-COMMONS-ZERO
|
||||
[3]: https://www.nsa.gov/
|
||||
[4]: https://www.giac.org/
|
||||
[5]: https://www.cisecurity.org/
|
||||
[6]: https://csrc.nist.gov/
|
||||
[7]: https://www.devsecops.cc/
|
||||
@@ -0,0 +1,47 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: (MjSeven)
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (Which programming languages should you learn?)
|
||||
[#]: via: (https://opensource.com/article/19/2/which-programming-languages-should-you-learn)
|
||||
[#]: author: (Marty Kalin https://opensource.com/users/mkalindepauledu)
|
||||
|
||||
应该学习哪种编程语言？
|
||||
======
|
||||
学习一门新的编程语言是在你的职业生涯中继续前进的好方法，但是应该学习哪一门呢？
|
||||
|
||||
|
||||
如果你想要在编程生涯中起步或继续前进，那么学习一门新语言是一个聪明的主意。但是，大量活跃使用的语言引发了一个问题：哪种编程语言是最好学习的？要回答这个问题，让我们从一个简单的问题开始：你想做什么样的程序？
|
||||
|
||||
如果你想在客户端进行网络编程，那么特定语言 HTML、CSS 和 JavaScript（一种看似无穷无尽的方言）是必须要学习的。
|
||||
<to 校正：这里是 JavaScript 的形容？>
|
||||
|
||||
如果你想在服务器端进行 Web 编程，那么选项包括常见的通用语言：C++, Golang, Java, C#, Node.js, Perl, Python, Ruby 等等。当然，服务器程序与数据存储（例如关系数据库和其他数据库）打交道，这意味着 SQL 等查询语言可能会发挥作用。
|
||||
|
||||
如果你正在为移动设备编写本地应用程序，那么了解目标平台非常重要。对于 Apple 设备，Swift 已经取代 Objective C 成为首选语言。对于 Android 设备，Java（带有专用库和工具集）仍然是主要语言。有一些特殊语言，如 与 C# 一起使用的 Xamarin，可以为 Apple、Android 和 Windows 设备生成特定于平台的代码。
|
||||
|
||||
那么通用语言呢？通常有各种各样的选择。在*动态*或*脚本*语言（如 Perl、Python 和 Ruby）中，有一些新东西，如 Node.js。java 和 C# 的相似之处比它们的粉丝愿意承认的还要多，仍然是针对虚拟机（分别是 JVM 和 CLR）的主要*静态编译*语言。在编译为*原生可执行文件*的语言中，C++ 仍然处于混合状态，以及后来的 Golang 和 Rust 等。通用*函数*语言比比皆是（如 Clojure、Haskell、Erlang、F#、Lisp 和 Scala），它们通常都有热情投入的社区。值得注意的是，面向对象语言（如 Java 和 C#）已经添加了函数构造（特别是 lambdas），而动态语言从一开始就有函数构造。
|
||||
|
||||
让我以 C 语言结尾，它是一种小巧，优雅，可扩展的语言，不要与 C++ 混淆。现代操作系统主要用 C 语言编写，其余的用汇编语言编写。任何平台上的标准库大多数都是用 C 语言编写的。例如，任何打印 `Hello, world!` 这种问候都是通过调用名为 **write** 的 C 库函数来实现的。
|
||||
|
||||
C 作为一种可移植的汇编语言，公开了其他高级语言有意隐藏的底层系统的详细信息。因此，理解 C 可以更好地掌握程序如何竞争执行所需的共享系统资源（如处理器，内存和 I/O 设备）。C 语言既高级又接近硬件，因此在性能方面无与伦比，当然，汇编语言除外。最后，C 是编程语言中的通用语言，几乎所有通用语言都支持一种或另一种形式的 C 调用。
|
||||
|
||||
有关现代 C 语言的介绍，参考我的书籍 [C Programming: Introducing Portable Assembler][1]。无论你怎么做，学习 C 语言，你会学到比另一种编程语言多得多的东西。
|
||||
|
||||
你认为学习哪些编程语言很重要？你是否同意这些建议？在评论告知我们！
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/19/2/which-programming-languages-should-you-learn
|
||||
|
||||
作者：[Marty Kalin][a]
|
||||
选题：[lujun9972][b]
|
||||
<!-- <!-- 译者：[MjSeven](https://github.com/MjSeven) --> -->
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://opensource.com/users/mkalindepauledu
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://www.amazon.com/dp/1977056954?ref_=pe_870760_150889320
|
||||
@@ -0,0 +1,129 @@
|
||||
[#]: collector: "lujun9972"
|
||||
[#]: translator: "zgj1024 "
|
||||
[#]: reviewer: " "
|
||||
[#]: publisher: " "
|
||||
[#]: url: " "
|
||||
[#]: subject: "Why DevOps is the most important tech strategy today"
|
||||
[#]: via: "https://opensource.com/article/19/3/devops-most-important-tech-strategy"
|
||||
[#]: author: "Kelly AlbrechtWilly-Peter Schaub https://opensource.com/users/ksalbrecht/users/brentaaronreed/users/wpschaub/users/wpschaub/users/ksalbrecht"
|
||||
|
||||
为何 DevOps 是如今最重要的技术策略
|
||||
======
|
||||
消除一些关于 DevOps 的疑惑
|
||||
![CICD with gears][1]
|
||||
|
||||
很多人初学 [DevOps][2] 时，看到它其中一个结果就问这个是如何得来的。其实理解这部分 Devops 的怎样实现并不重要，重要的是——理解（使用） DevOps 策略的原因——这是做一个行业的领导者还是追随者的差别。
|
||||
|
||||
你可能会听过些 Devops 的难以置信的成果，例如生产环境非常有弹性，“混世猴子”（[Chaos Monkey][3]）程序运行时，将周围的连接随机切断，每天仍可以处理数千个版本。这是令人印象深刻的，但就其本身而言，这是一个 DevOps 的无力案例，本质上会被一个[反例][4]困扰：DevOps 环境有弹性是因为没有观察到严重的故障。。。还没有。
|
||||
|
||||
有很多关于 DevOps 的疑惑，并且许多人还在尝试弄清楚它的意义。下面是来自我 LinkedIn Feed 中的某个人的一个案例：
|
||||
|
||||
> 最近我参加一些 #DevOps 的交流会，那里一些演讲人好像在倡导 #敏捷开发是 DevOps 的子集。不知为何，我的理解洽洽相反。
|
||||
>
|
||||
> 能听一下你们的想法吗？你认为敏捷开发和 DevOps 之间是什么关系呢？
|
||||
>
|
||||
> 1. DevOps 是敏捷开发的子集
|
||||
> 2. 敏捷开发 是 DevOps 的子集
|
||||
> 3. DevOps 是敏捷开发的扩展，从敏捷开发结束的地方开始
|
||||
> 4. DevOps 是敏捷开发的新版本
|
||||
>
|
||||
|
||||
科技行业的专业人士在那篇 LinkedIn 的帖子上达标各样的答案，你会怎样回复呢？
|
||||
|
||||
### DevOps源于精益和敏捷
|
||||
|
||||
如果我们从亨利福特的战略和丰田生产系统对福特车型的改进（的历史）开始， DevOps 就更有意义了。精益制造就诞生在那段历史中，人们对精益制作进行了良好的研究。James P. Womack 和 Daniel T. Jones 将精益思维（ [Lean Thinking][5]）提炼为五个原则：
|
||||
1. 指明客户所需的价值
|
||||
2. 确定提供该价值的每个产品的价值流，并对当前提供该价值所需的所有浪费步骤提起挑战
|
||||
3. 使产品通过剩余的增值步骤持续流动
|
||||
4. 在可以连续流动的所有步骤之间引入拉力
|
||||
5. 管理要尽善尽美，以便为客户服务所需的步骤数量和时间以及信息量持续下降
|
||||
|
||||
|
||||
Lean seeks to continuously remove waste and increase the flow of value to the customer. This is easily recognizable and understood through a core tenet of lean: single piece flow. We can do a number of activities to learn why moving single pieces at a time is magnitudes faster than batches of many pieces; the [Penny Game][6] and the [Airplane Game][7] are two of them. In the Penny Game, if a batch of 20 pennies takes two minutes to get to the customer, they get the whole batch after waiting two minutes. If you move one penny at a time, the customer gets the first penny in about five seconds and continues getting pennies until the 20th penny arrives approximately 25 seconds later.
|
||||
|
||||
精益致力于持续消除浪费并增加客户的价值流动。这很容易识别并明白精益的核心原则：单一流。我们可以做一些游戏去了解为何同一时间移动单个比批量移动要快得多。其中的两个游戏是[硬币游戏][6]和[飞机游戏][7]。在硬币游戏中，如果一批 20 个硬币到顾客手中要用 2 分钟，顾客等 2 分钟后能拿到整批硬币。如果一次只移动一个硬币，顾客会在 5 秒内得到第一枚硬币，并会持续获得硬币，直到在大约 25 秒后第 20 个硬币到达。（译者注：有相关的视频的）
|
||||
|
||||
这是巨大的不同，但是不是生活中的所有事都像硬币游戏那样简单并可预测的。这就是敏捷的出现的原因。我们当然看到了高效绩敏捷团队的精益原则，但这些团队需要的不仅仅是精益去做他们要做的事。
|
||||
|
||||
为了能够处理典型的软件开发任务的不可预见性和变化，敏捷开发的方法论会将重点放在意识、审议、决策和行动上，以便在不断变化的现实中调整。例如，敏捷框架（如 srcum）通过每日站立会议和冲刺评审会议等仪式提高意识。如果 scrum 团队意识到新的事实，框架允许并鼓励他们在必要时及时调整路线。
|
||||
|
||||
要使团队做出这些类型的决策，他们需要高度信任的环境中的自我组织能力。以这种方式工作的高效绩敏捷团队在不断调整的同时实现快速的价值流，消除错误方向上的浪费。
|
||||
|
||||
### 最佳批量大小
|
||||
|
||||
要了解 DevOps 在软件开发中的请强大功能，这会帮助我们理解批处理大小的经济学。请考虑以下来自Donald Reinertsen 的[产品开发流程原则][8]的U曲线优化示例：
|
||||
|
||||
![U-curve optimization illustration of optimal batch size][9]
|
||||
|
||||
这可以类比杂货店购物来解释。假设你需要买一些鸡蛋，而你住的地方离商店只有 30 分的路程。买一个鸡蛋（图种最左边）意味着每次要花 30 分钟的路程，这就是你的_交易成本_。_持有成本_可能是鸡蛋变质和在你的冰箱中持续地占用空间。_总成本_是_交易成本_加上你的_持有成本_。这 U 型曲线解释了为什么对大部分来说，一次买一打鸡蛋是他们的_最佳批量大小_。如果你就住在商店的旁边，步行到那里不会花费你任何的时候，你可能每次只会买一小盒鸡蛋，以此来节省冰箱的空间并享受新鲜的鸡蛋。
|
||||
|
||||
这 U 型优化曲线可以说明为什么在成功敏捷转换中生产力会显著提高。考虑敏捷转换对组织决策的影响。在传统的分级组织中，决策权是集中的。这会导致较少的人做更大的决策。敏捷方法论会有效地降低组织决策中的交易成本，方法是将决策分散到最被人熟知的认识和信息的位置：跨越高度信任，自组织的敏捷团队。
|
||||
|
||||
下面的动画演示了降低事务成本后，最佳批量大小是如何向左移动。在更频繁地做出更快的决策方面，你不能低估组织的价值。
|
||||
|
||||
![U-curve optimization illustration][10]
|
||||
|
||||
### DevOps 适合哪些地方
|
||||
|
||||
自动化是 DevOps 最知名的事情之一。前面的插图非常详细地展示了自动化的价值。通过自动化，我们将交易成本降低到接近零，实质上是免费进行测试和部署。这使我们可以利用越来越小的批量工作。较小批量的工作更容易理解、提交、测试、审查和知道何时能完成。这些较小的批量大小也包含较少的差异和风险，使其更易于部署，如果出现问题，可以进行故障排除和恢复。通过自动化与扎实的敏捷实践相结合，我们可以使我们的功能开发非常接近单件流程，从而快速，持续地为客户提供价值。
|
||||
|
||||
更传统地说，DevOps 被理解为一种打破开发团队和运营团队之间混乱局面的方法。在这个模型中，开发团队开发新的功能，而运营团队则保持系统的稳定和平稳运行。摩擦的发生是因为开发过程中的新功能将更改引入到系统中，从而增加了停机的风险，运营团队并不认为要对此负责，但无论如何都必须处理这一问题。DevOps 不仅仅尝试让人们一起工作，更重要的是尝试在复杂的环境中安全地进行更频繁的更改。
|
||||
|
||||
我们可以向 [Ron Westrum][11] 寻求有关在复杂组织中实现安全性的研究。在研究为什么有些组织比其他组织更安全时，他发现组织的文化可以预测其安全性。他确定了三种文化：病态，官僚主义的和生产式的。他发现病理的可以预测安全性较低，而生产式文化被预测为更安全（例如，在他的主要研究领域中，飞机坠毁或意外住院死亡的数量要少得多）。
|
||||
|
||||
![Three types of culture identified by Ron Westrum][12]
|
||||
|
||||
高效的 DevOps 团队通过精益和敏捷的实践实现了一种生成性文化，这表明速度和安全性是互补的，或者说是同一个问题的两个方面。通过将决策和功能的最佳批量大小减少到非常小，DevOps 实现了更快的信息流和价值，同时消除了浪费并降低了风险。
|
||||
|
||||
与 Westrum的研究一致，在提高安全性和可靠性的同时，变化也很容易发生。。当一个敏捷的 DevOps 团队被信任做出自己的决定时，我们将获得 DevOps 目前最为人所知的工具和技术：自动化和持续交付。通过这种自动化，交易成本比以往任何时候都进一步降低，并且实现了近乎单一的精益流程，每天创造数千个决策和发布的潜力，正如我们在高效绩的 DevOps 组织中看到的那样
|
||||
|
||||
### 流动、反馈、学习
|
||||
|
||||
DevOps 并不止于此。我们主要讨论了 DevOps 实现了革命性的流程，但通过类似的努力可以进一步放大精益和敏捷实践，从而实现更快的反馈循环和更快的学习。在[_DevOps手册_][13] 中，作者除了详细解释快速流程外， DevOps 如何在整个价值流中实现遥测，从而获得快速且持续的反馈。此外，利用[精益求精的突破][14]和scrum 的[回顾][15]，高效的 DevOps 团队将不断推动学习和持续改进深入到他们的组织的基础，实现软件产品开发行业的精益制造革命。
|
||||
|
||||
|
||||
### 从 DevOps 评估开始
|
||||
|
||||
利用 DevOps 的第一步是，经过大量研究或在 DevOps 顾问和教练的帮助下，对高效绩 DevOps 团队中始终存在的一系列维度进行评估。评估应确定需要改进的薄弱或不存在的团队规范。对评估的结果进行评估，以找到具有高成功机会的快速获胜焦点领域，从而产生高影响力的改进。快速获胜非常重要，能让团队获取解决更具挑战性领域所需的动力。团队应该产生可以快速尝试的想法，并开始关注 DevOps 转型。
|
||||
|
||||
一段时间后，团队应重新评估相同的维度，以衡量改进并确立新的高影响力重点领域，并再次采纳团队的新想法。一位好的教练将根据需要进行咨询、培训、指导和支持，直到团队拥有自己的持续改进方案，并通过不断地重新评估、试验和学习，在所有维度上实现近乎一致。
|
||||
|
||||
在本文的[第二部分][16]中，我们将查看 Drupal 社区中 DevOps 调查的结果，并了解最有可能找到快速获胜的位置。
|
||||
|
||||
* * *
|
||||
|
||||
_Rob_ _Bayliss and Kelly Albrecht will present[DevOps: Why, How, and What][17] and host a follow-up [Birds of a][18]_ [_Feather_][18] _[discussion][18] at [DrupalCon 2019][19] in Seattle, April 8-12._
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/19/3/devops-most-important-tech-strategy
|
||||
|
||||
作者：[Kelly AlbrechtWilly-Peter Schaub][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/zgj1024)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://opensource.com/users/ksalbrecht/users/brentaaronreed/users/wpschaub/users/wpschaub/users/ksalbrecht
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/cicd_continuous_delivery_deployment_gears.png?itok=kVlhiEkc "CICD with gears"
|
||||
[2]: https://opensource.com/resources/devops
|
||||
[3]: https://github.com/Netflix/chaosmonkey
|
||||
[4]: https://en.wikipedia.org/wiki/Burden_of_proof_(philosophy)#Proving_a_negative
|
||||
[5]: https://www.amazon.com/dp/B0048WQDIO/ref=dp-kindle-redirect?_encoding=UTF8&btkr=1
|
||||
[6]: https://youtu.be/5t6GhcvKB8o?t=54
|
||||
[7]: https://www.shmula.com/paper-airplane-game-pull-systems-push-systems/8280/
|
||||
[8]: https://www.amazon.com/dp/B00K7OWG7O/ref=dp-kindle-redirect?_encoding=UTF8&btkr=1
|
||||
[9]: https://opensource.com/sites/default/files/uploads/batch_size_optimal_650.gif "U-curve optimization illustration of optimal batch size"
|
||||
[10]: https://opensource.com/sites/default/files/uploads/batch_size_650.gif "U-curve optimization illustration"
|
||||
[11]: https://en.wikipedia.org/wiki/Ron_Westrum
|
||||
[12]: https://opensource.com/sites/default/files/uploads/information_flow.png "Three types of culture identified by Ron Westrum"
|
||||
[13]: https://www.amazon.com/DevOps-Handbook-World-Class-Reliability-Organizations/dp/1942788002/ref=sr_1_3?keywords=DevOps+handbook&qid=1553197361&s=books&sr=1-3
|
||||
[14]: https://en.wikipedia.org/wiki/Kaizen
|
||||
[15]: https://www.scrum.org/resources/what-is-a-sprint-retrospective
|
||||
[16]: https://opensource.com/article/19/3/where-drupal-community-stands-devops-adoption
|
||||
[17]: https://events.drupal.org/seattle2019/sessions/devops-why-how-and-what
|
||||
[18]: https://events.drupal.org/seattle2019/bofs/devops-getting-started
|
||||
[19]: https://events.drupal.org/seattle2019
|
||||
@@ -1,58 +1,61 @@
|
||||
关于 /dev/urandom 的流言终结
|
||||
======
|
||||
|
||||
有很多关于 /dev/urandom 和 /dev/random 的流言在坊间不断流传。流言终究是流言。
|
||||
本篇文章里针对的都是今年的 Linux 操作系统，其他类 Unix 操作系统不在讨论范围内。
|
||||
有很多关于 `/dev/urandom` 和 `/dev/random` 的流言在坊间不断流传。然而流言终究是流言。
|
||||
|
||||
### /dev/urandom 不安全。加密用途必须使用 /dev/random。
|
||||
> 本篇文章里针对的都是近来的 Linux 操作系统，其它类 Unix 操作系统不在讨论范围内。
|
||||
|
||||
事实：/dev/urandom 才是类 Unix 操作系统下推荐的加密种子。
|
||||
**`/dev/urandom` 不安全。加密用途必须使用 `/dev/random`**
|
||||
|
||||
### /dev/urandom 是伪随机数生成器（PRND），而 /dev/random 是“真”随机数生成器。
|
||||
事实：`/dev/urandom` 才是类 Unix 操作系统下推荐的加密种子。
|
||||
|
||||
事实：他们两者本质上用的是同一种 CSPRNG （一种密码学伪随机数生成器）。他们之间细微的差别和“真”不“真”随机完全无关
|
||||
**`/dev/urandom` 是<ruby>伪随机数生成器<rt>pseudo random number generator</rt></ruby>（PRND），而 `/dev/random` 是“真”随机数生成器。**
|
||||
|
||||
### /dev/random 在任何情况下都是密码学应用更好地选择。即便 /dev/urandom 也同样安全，我们还是不应该用 urandom。
|
||||
事实：它们两者本质上用的是同一种 CSPRNG （一种密码学伪随机数生成器）。它们之间细微的差别和“真”不“真”随机完全无关
|
||||
|
||||
事实：/dev/random 有个很恶心人的问题：它是阻塞的。（译者：意味着请求都得逐个执行，等待前一个事件完成）
|
||||
**`/dev/random` 在任何情况下都是密码学应用更好地选择。即便 `/dev/urandom` 也同样安全，我们还是不应该用它。**
|
||||
|
||||
### 但阻塞不是好事吗！/dev/random 只会给出电脑收集的信息熵足以支持的随机量。/dev/urandom 在用完了所有熵的情况下还会不断吐不安全的随机数给你。
|
||||
事实：`/dev/random` 有个很恶心人的问题：它是阻塞的。（LCTT 译注：意味着请求都得逐个执行，等待前一个请求完成）
|
||||
|
||||
事实：这是误解。就算我们不去考虑应用层面后续对随机种子的用法，“用完信息熵池”这个概念本身就不存在。仅仅 256 bits 的熵就足以生成计算上安全的随机数很长，很长一段时间了。
|
||||
**但阻塞不是好事吗！`/dev/random` 只会给出电脑收集的信息熵足以支持的随机量。`/dev/urandom` 在用完了所有熵的情况下还会不断吐不安全的随机数给你。**
|
||||
|
||||
问题的关键还在后头：/dev/random 怎么知道有系统会多少可用的信息熵？接着看！
|
||||
事实：这是误解。就算我们不去考虑应用层面后续对随机种子的用法，“用完信息熵池”这个概念本身就不存在。仅仅 256 位的熵就足以生成计算上安全的随机数很长、很长的一段时间了。
|
||||
|
||||
### 但密码学家老是讨论重新选种子（re-seeding）。这难道不和上一条冲突吗？
|
||||
问题的关键还在后头：`/dev/random` 怎么知道有系统会*多少*可用的信息熵？接着看！
|
||||
|
||||
**但密码学家老是讨论重新选种子（re-seeding）。这难道不和上一条冲突吗？**
|
||||
|
||||
事实：你说的也没错！某种程度上吧。确实，随机数生成器一直在使用系统信息熵的状态重新选种。但这么做（一部分）是因为别的原因。
|
||||
|
||||
这样说吧，我没有说引入新的信息熵是坏的。更多的熵肯定更好。我只是说在熵池低的时候阻塞是没必要的。
|
||||
|
||||
### 好，就算你说的都对，但是 /dev/(u)random 的 man 页面和你说的也不一样啊！到底有没有专家同意你说的这堆啊？
|
||||
**好，就算你说的都对，但是 `/dev/(u)random` 的 man 页面和你说的也不一样啊！到底有没有专家同意你说的这堆啊？**
|
||||
|
||||
事实：其实 man 页面和我说的不冲突。它看似好像在说 /dev/urandom 对密码学用途来说不安全，但如果你真的理解这堆密码学术语你就知道他说的并不是这个意思。
|
||||
事实：其实 man 页面和我说的不冲突。它看似好像在说 `/dev/urandom` 对密码学用途来说不安全，但如果你真的理解这堆密码学术语你就知道它说的并不是这个意思。
|
||||
|
||||
man 页面确实说在一些情况下推荐使用 /dev/random （我觉得也没问题，但绝对不是说必要的），但它也推荐在大多数“一般”的密码学应用下使用 /dev/urandom 。
|
||||
man 页面确实说在一些情况下推荐使用 `/dev/random` （我觉得也没问题，但绝对不是说必要的），但它也推荐在大多数“一般”的密码学应用下使用 `/dev/urandom` 。
|
||||
|
||||
虽然诉诸权威一般来说不是好事，但在密码学这么严肃的事情上，和专家统一意见是很有必要的。
|
||||
|
||||
所以说呢，还确实有一些专家和我的一件事一致的：/dev/urandom 就应该是类 UNIX 操作系统下密码学应用的首选。显然的，是他们的观点说服了我而不是反过来的。
|
||||
所以说呢，还确实有一些*专家*和我的一件事一致的：`/dev/urandom` 就应该是类 UNIX 操作系统下密码学应用的首选。显然的，是他们的观点说服了我而不是反过来的。
|
||||
|
||||
------
|
||||
|
||||
难以相信吗？觉得我肯定错了？读下去看我能不能说服你。
|
||||
|
||||
我尝试不讲太高深的东西，但是有两点内容必须先提一下才能让我们接着论证观点。
|
||||
|
||||
首当其冲的，什么是随机性，或者更准确地：我们在探讨什么样的随机性？
|
||||
首当其冲的，*什么是随机性*，或者更准确地：我们在探讨什么样的随机性？
|
||||
|
||||
另外一点很重要的是，我没有尝试以说教的态度对你们写这段话。我写这篇文章是为了日后可以在讨论起的时候指给别人看。比 140 字长（译者：推特长度）。这样我就不用一遍遍重复我的观点了。能把论点磨炼成一篇文章本身就很有助于将来的讨论。
|
||||
另外一点很重要的是，我*没有尝试以说教的态度*对你们写这段话。我写这篇文章是为了日后可以在讨论起的时候指给别人看。比 140 字长（LCTT 译注：推特长度）。这样我就不用一遍遍重复我的观点了。能把论点磨炼成一篇文章本身就很有助于将来的讨论。
|
||||
|
||||
并且我非常乐意听到不一样的观点。但我只是认为单单地说 /dev/urandom 坏是不够的。你得能指出到底有什么问题，并且剖析他们。
|
||||
并且我非常乐意听到不一样的观点。但我只是认为单单地说 `/dev/urandom` 坏是不够的。你得能指出到底有什么问题，并且剖析它们。
|
||||
|
||||
### 你是在说我笨？！
|
||||
|
||||
绝对没有！
|
||||
|
||||
事实上我自己也相信了 “/dev/urandom 不安全的” 好些年。这几乎不是我们的错，因为那么德高望重的人在 Usenet，论坛，推特上根我们重复这个观点。甚至连 man page 都似是而非地说着。我们当年怎么可能打发诸如“信息熵太低了”这种看上去就很让人信服的观点呢？
|
||||
事实上我自己也相信了 “`/dev/urandom` 是不安全的” 好些年。这几乎不是我们的错，因为那么德高望重的人在 Usenet、论坛、推特上跟我们重复这个观点。甚至*连 man 手册*都似是而非地说着。我们当年怎么可能鄙视诸如“信息熵太低了”这种看上去就很让人信服的观点呢？
|
||||
|
||||
整个流言之所以如此广为流传不是因为人们太蠢，而是因为但凡有点关于信息熵和密码学概念的人都会觉得这个说法很有道理。直觉似乎都在告诉我们这流言讲的很有道理。很不幸直觉在密码学里通常不管用，这次也一样。
|
||||
|
||||
@@ -62,9 +65,9 @@ man 页面确实说在一些情况下推荐使用 /dev/random （我觉得也没
|
||||
|
||||
我不想搞的太复杂以至于变成哲学范畴的东西。这种讨论很容易走偏因为随机模型大家见仁见智，讨论很快变得毫无意义。
|
||||
|
||||
在我看来真随机的“试金石”是量子效应。一个光子穿过或不穿过一个50%的半透镜。或者观察一个放射性粒子衰变。这类东西是现实世界最接近真随机的东西。当然，有些人也不相信这类过程是真随机的，或者这个世界根本不存在任何随机性。这个就百家争鸣我也不好多说什么了。
|
||||
在我看来“真随机”的“试金石”是量子效应。一个光子穿过或不穿过一个半透镜。或者观察一个放射性粒子衰变。这类东西是现实世界最接近真随机的东西。当然，有些人也不相信这类过程是真随机的，或者这个世界根本不存在任何随机性。这个就百家争鸣了，我也不好多说什么了。
|
||||
|
||||
密码学家一般都会通过不去讨论什么是“真随机”来避免这种争论。他们更关心的是不可预测性。只要没有任何方法能猜出下一个随机数就可以了。所以当你以密码学应用为前提讨论一个随机数好不好的时候，在我看来这才是最重要的。
|
||||
密码学家一般都会通过不去讨论什么是“真随机”来避免这种争论。它们更关心的是<ruby>不可预测性<rt> unpredictability</rt></ruby>。只要没有*任何*方法能猜出下一个随机数就可以了。所以当你以密码学应用为前提讨论一个随机数好不好的时候，在我看来这才是最重要的。
|
||||
|
||||
无论如何，我不怎么关心“哲学上安全”的随机数，这也包括别人嘴里的“真”随机数。
|
||||
|
||||
@@ -72,25 +75,25 @@ man 页面确实说在一些情况下推荐使用 /dev/random （我觉得也没
|
||||
|
||||
但就让我们退一步说，你有了一个“真”随机变量。你下一步做什么呢？
|
||||
|
||||
你把他们打印出来然后挂在墙上来战士量子宇宙的美与和谐？牛逼！我很理解你。
|
||||
你把它们打印出来然后挂在墙上来展示量子宇宙的美与和谐？牛逼！我很理解你。
|
||||
|
||||
但是等等，你说你要用他们？做密码学用途？额，那这就废了，因为这事情就有点复杂了。
|
||||
但是等等，你说你要*用*它们？做密码学用途？额，那这就废了，因为这事情就有点复杂了。
|
||||
|
||||
事情是这样的，你的真随机，量子力学加护的随机数即将被用进不理想的现实世界程序里。
|
||||
|
||||
因为我们使用的大多数算法并不是 ### 理论信息学上安全的。**他们只能提供** 计算意义上的安全。我能想到为数不多的例外就只有 Shamir 密钥分享 和 One-time pad 算法。并且就算前者是名副其实的（如果你实际打算用的话），后者则毫无可行性可言。
|
||||
因为我们使用的大多数算法并不是<ruby>理论信息学<rt>information-theoretic</rt></ruby>上安全的。它们“只能”提供 **计算意义上的安全**。我能想到为数不多的例外就只有 Shamir 密钥分享 和 One-time pad 算法。并且就算前者是名副其实的（如果你实际打算用的话），后者则毫无可行性可言。
|
||||
|
||||
但所有那些大名鼎鼎的密码学算法，AES，RSA，Diffie-Hellman, 椭圆曲线，还有所有那些加密软件包，OpenSSL，GnuTLS，Keyczar，你的操作系统的加密 API，都仅仅是计算意义上的安全的。
|
||||
但所有那些大名鼎鼎的密码学算法，AES、RSA、Diffie-Hellman、椭圆曲线，还有所有那些加密软件包，OpenSSL、GnuTLS、Keyczar、你的操作系统的加密 API，都仅仅是计算意义上的安全的。
|
||||
|
||||
那区别是什么呢？理论信息学上的安全肯定是安全的，句号。其他那些的算法都可能在理论上被拥有无限计算力的穷举破解。我们依然愉快地使用他们因为全世界的计算机加起来都不可能在宇宙年龄的时间里破解，至少现在是这样。而这就是我们文章里说的“不安全”。
|
||||
那区别是什么呢？理论信息学上的安全肯定是安全的，绝对是，其它那些的算法都可能在理论上被拥有无限计算力的穷举破解。我们依然愉快地使用它们因为全世界的计算机加起来都不可能在宇宙年龄的时间里破解，至少现在是这样。而这就是我们文章里说的“不安全”。
|
||||
|
||||
除非哪个聪明的家伙破解了算法本身——在只需要极少量计算力的情况下。这也是每个密码学家梦寐以求的圣杯：破解 AES 本身，破解 RSA 算法本身。
|
||||
除非哪个聪明的家伙破解了算法本身——在只需要极少量计算力的情况下。这也是每个密码学家梦寐以求的圣杯：破解 AES 本身、破解 RSA 本身等等。
|
||||
|
||||
所以现在我们来到了更底层的东西：随机数生成器，你坚持要“真随机”而不是“伪随机”。但是没过一会儿你的真随机数就被喂进了你极为鄙视的伪随机算法里了！
|
||||
|
||||
真相是，如果我们最先进的 hash 算法被破解了，或者最先进的块加密被破解了，你得到这些那些“哲学上不安全的”甚至无所谓了，因为反正你也没有安全的应用方法了。
|
||||
|
||||
所以喂计算性上安全的随机数给你仅仅是计算性上安全的算法就可以了，换而言之，用 /dev/urandom。
|
||||
所以把计算性上安全的随机数喂给你的仅仅是计算性上安全的算法就可以了，换而言之，用 `/dev/urandom`。
|
||||
|
||||
### Linux 随机数生成器的构架
|
||||
|
||||
@@ -100,19 +103,19 @@ man 页面确实说在一些情况下推荐使用 /dev/random （我觉得也没
|
||||
|
||||
![image: mythical structure of the kernel's random number generator][1]
|
||||
|
||||
“真随机数”，尽管可能有点瑕疵，进入操作系统然后它的熵立刻被加入内部熵计数器。然后经过去 bias 和“漂白”之后它进入内核的熵池，然后 /dev/random 和 /dev/urandom 从里面生成随机数。
|
||||
“真随机数”，尽管可能有点瑕疵，进入操作系统然后它的熵立刻被加入内部熵计数器。然后经过“矫偏”和“漂白”之后它进入内核的熵池，然后 `/dev/random` 和 `/dev/urandom` 从里面生成随机数。
|
||||
|
||||
“真”随机数生成器，/dev/random，直接从池里选出随机数，如果熵计数器表示能满足需要的数字大小，那就吐出数字并且减少熵计数。如果不够的话，他会阻塞程序直至有足够的熵进入和系统。
|
||||
“真”随机数生成器，`/dev/random`，直接从池里选出随机数，如果熵计数器表示能满足需要的数字大小，那就吐出数字并且减少熵计数。如果不够的话，它会阻塞程序直至有足够的熵进入系统。
|
||||
|
||||
这里很重要一环是 /dev/random 几乎直接把那些进入系统的随机性吐了出来，不经扭曲。
|
||||
这里很重要一环是 `/dev/random` 几乎只是仅经过必要的“漂白”后就直接把那些进入系统的随机性吐了出来，不经扭曲。
|
||||
|
||||
而对 /dev/urandom 来说，事情是一样的。除了当没有足够的熵的时候，它不会阻塞，而会从一直在运行的伪随机数生成器里吐出“底质量”的随机数。这个 CSPRNG 只会用“真随机数”生成种子一次（或者好几次，这不重要），但你不能特别相信它。
|
||||
而对 `/dev/urandom` 来说，事情是一样的。除了当没有足够的熵的时候，它不会阻塞，而会从一直在运行的伪随机数生成器（当然，是密码学安全的，CSPRNG）里吐出“低质量”的随机数。这个 CSPRNG 只会用“真随机数”生成种子一次（或者好几次，这不重要），但你不能特别相信它。
|
||||
|
||||
在这种对随机数生成的理解下，很多人会觉得在 Linux 下尽量避免 /dev/urandom 看上去有那么点道理。
|
||||
在这种对随机数生成的理解下，很多人会觉得在 Linux 下尽量避免 `/dev/urandom` 看上去有那么点道理。
|
||||
|
||||
因为要么你有足够多的熵，你会相当于用了 /dev/random。要么没有，那你就会从几乎没有高熵输入的 CSPRNG 那里得到一个低质量的随机数。
|
||||
因为要么你有足够多的熵，你会相当于用了 `/dev/random`。要么没有，那你就会从几乎没有高熵输入的 CSPRNG 那里得到一个低质量的随机数。
|
||||
|
||||
看上去很邪恶是吧？很不幸的是这种看法是完全错误的。实际上，随机数生成器的构架更像是这样的。
|
||||
看上去很邪恶是吧？很不幸的是这种看法是完全错误的。实际上，随机数生成器的构架更像是下面这样的。
|
||||
|
||||
#### 更好地简化
|
||||
|
||||
@@ -120,66 +123,65 @@ man 页面确实说在一些情况下推荐使用 /dev/random （我觉得也没
|
||||
|
||||
![image: actual structure of the kernel's random number generator before Linux 4.8][2]
|
||||
|
||||
这是个很粗糙的简化。实际上不仅有一个，而是三个熵池。一个主池，另一个给 /dev/random，还有一个给 /dev/urandom，后两者依靠从主池里获取熵。这三个池都有各自的熵计数器，但二级池（后两个）的计数器基本都在0附近，而“新鲜”的熵总在需要的时候从主池流过来。同时还有好多混合和回流进系统在同时进行。整个过程对于这篇文档来说都过于复杂了我们跳过。
|
||||
> 这是个很粗糙的简化。实际上不仅有一个，而是三个熵池。一个主池，另一个给 `/dev/random`，还有一个给 `/dev/urandom`，后两者依靠从主池里获取熵。这三个池都有各自的熵计数器，但二级池（后两个）的计数器基本都在 0 附近，而“新鲜”的熵总在需要的时候从主池流过来。同时还有好多混合和回流进系统在同时进行。整个过程对于这篇文档来说都过于复杂了我们跳过。
|
||||
|
||||
但你看到最大的区别了吗？ CSPRNG 并不是和随机数生成器一起跑用来填充 /dev/urandom 需要输出但熵不够的时候。CSPRNG 是整个随机数生成过程的内部组件之一。从来就没有什么 /dev/random 直接从池里输出纯纯的随机性。每个随机源的输入都在 CSPRNG 里充分混合和 hash 过了，这一切都发生在实际变成一个随机数，被/dev/urandom 或者 /dev/random 吐出去之前。
|
||||
你看到最大的区别了吗？CSPRNG 并不是和随机数生成器一起跑的，以 `/dev/urandom` 需要输出但熵不够的时候进行填充。CSPRNG 是整个随机数生成过程的内部组件之一。从来就没有什么 `/dev/random` 直接从池里输出纯纯的随机性。每个随机源的输入都在 CSPRNG 里充分混合和散列过了，这一切都发生在实际变成一个随机数，被 `/dev/urandom` 或者 `/dev/random` 吐出去之前。
|
||||
|
||||
另外一个重要的区别是是这里没有熵计数器的任何事情，只有预估。一个源给你的熵的量并不是什么很明确能直接得到的数字。你得预估它。注意，如果你太乐观地预估了它，那 /dev/random 最重要的特性——只给出熵允许的随机量——就荡然无存了。很不幸的，预估熵的量是很困难的。
|
||||
另外一个重要的区别是这里没有熵计数器的任何事情，只有预估。一个源给你的熵的量并不是什么很明确能直接得到的数字。你得预估它。注意，如果你太乐观地预估了它，那 `/dev/random` 最重要的特性——只给出熵允许的随机量——就荡然无存了。很不幸的，预估熵的量是很困难的。
|
||||
|
||||
Linux 内核只使用事件的到达时间来预估熵的量。它通过多项式插值，某种模型，来预估实际的到达时间有多“出乎意料”。这种多项式插值的方法到底是不是好的预估熵量的方法本身就是个问题。同时硬件情况会不会以某种特定的方式影响到达时间也是个问题。而所有硬件的取样率也是个问题，因为这基本上就直接决定了随机数到达时间的颗粒度。
|
||||
|
||||
说到最后，至少现在看来，内核的熵预估还是不错的。这也意味着它比较保守。有些人会具体地讨论它有多好，这都超出我的脑容量了。就算这样，如果你坚持不想在没有足够多的熵的情况下吐出随机数，那你看到这里可能还会有一丝紧张。我睡的就很香了，因为我不关心熵预估什么的。
|
||||
|
||||
最后强调一下终点：/dev/random 和 /dev/urandom 都是被同一个 CSPRNG 喂的输入。只有他们在用完各自熵池（根据某种预估标准）的时候，他们的行为会不同：/dev/random 阻塞，/dev/urandom 不阻塞。
|
||||
最后强调一下终点：`/dev/random` 和 `/dev/urandom` 都是被同一个 CSPRNG 喂的输入。只有它们在用完各自熵池（根据某种预估标准）的时候，它们的行为会不同：`/dev/random` 阻塞，`/dev/urandom` 不阻塞。
|
||||
|
||||
##### Linux 4.8 以后
|
||||
|
||||
在 Linux 4.8 里，/dev/random 和 /dev/urandom 的等价性被放弃了。现在 /dev/urandom 的输出不来自于熵池，而是直接从 CSPRNG 来。
|
||||
在 Linux 4.8 里，`/dev/random` 和 `/dev/urandom` 的等价性被放弃了。现在 `/dev/urandom` 的输出不来自于熵池，而是直接从 CSPRNG 来。
|
||||
|
||||
![image: actual structure of the kernel's random number generator from Linux 4.8 onward][3]
|
||||
|
||||
我们很快会理解为什么这不是一个安全问题。
|
||||
*我们很快会理解*为什么这不是一个安全问题。
|
||||
|
||||
### 阻塞有什么问题？
|
||||
|
||||
你有没有需要等着 /dev/random 来吐随机数？比如在虚拟机里生成一个 PGP 密钥？或者访问一个在生成会话密钥的网站？
|
||||
你有没有需要等着 `/dev/random` 来吐随机数？比如在虚拟机里生成一个 PGP 密钥？或者访问一个在生成会话密钥的网站？
|
||||
|
||||
这些都是问题。阻塞本质上会降低可用性。换而言之你的系统不干你让它干的事情。不用我说，这是不好的。要是它不 work 你干嘛搭建它呢？
|
||||
这些都是问题。阻塞本质上会降低可用性。换而言之你的系统不干你让它干的事情。不用我说，这是不好的。要是它不干活你干嘛搭建它呢？
|
||||
|
||||
我在工厂自动化里做过和安全相关的系统。猜猜看安全系统失效的主要原因是什么？被错误操作。就这么简单。很多安全措施的流程让工人恼火了。比如时间太长，或者太不方便。你要知道人很会找捷径来“解决”问题。
|
||||
> 我在工厂自动化里做过和安全相关的系统。猜猜看安全系统失效的主要原因是什么？被错误操作。就这么简单。很多安全措施的流程让工人恼火了。比如时间太长，或者太不方便。你要知道人很会找捷径来“解决”问题。
|
||||
|
||||
但其实有个更深刻的问题：人们不喜欢被打断。他们会找一些绕过的方法，把一些诡异的东西接在一起仅仅因为这样能用。一般人根本不知道什么密码学什么乱七八糟的，至少正常的人是这样吧。
|
||||
但其实有个更深刻的问题：人们不喜欢被打断。它们会找一些绕过的方法，把一些诡异的东西接在一起仅仅因为这样能用。一般人根本不知道什么密码学什么乱七八糟的，至少正常的人是这样吧。
|
||||
|
||||
为什么不禁止调用 `random()`？为什么不随便在论坛上找个人告诉你用写奇异的 ioctl 来增加熵计数器呢？为什么不干脆就把 SSL 加密给关了算了呢？
|
||||
|
||||
到头来如果东西太难用的话，你的用户就会被迫开始做一些降低系统安全性的事情——你甚至不知道他们会做些什么。
|
||||
到头来如果东西太难用的话，你的用户就会被迫开始做一些降低系统安全性的事情——你甚至不知道它们会做些什么。
|
||||
|
||||
我们很容易会忽视可用性之类的重要性。毕竟安全第一对吧？所以比起牺牲安全，不可用，难用，不方便都是次要的？
|
||||
|
||||
这种二元对立的想法是错的。阻塞不一定就安全了。正如我们看到的，/dev/urandom 直接从 CSPRNG 里给你一样好的随机数。用它不好吗！
|
||||
这种二元对立的想法是错的。阻塞不一定就安全了。正如我们看到的，`/dev/urandom` 直接从 CSPRNG 里给你一样好的随机数。用它不好吗！
|
||||
|
||||
### CSPRNG 没问题
|
||||
|
||||
现在情况听上去很沧桑。如果连高质量的 /dev/random 都是从一个 CSPRNG 里来的，我们怎么敢在高安全性的需求上使用它呢？
|
||||
现在情况听上去很沧桑。如果连高质量的 `/dev/random` 都是从一个 CSPRNG 里来的，我们怎么敢在高安全性的需求上使用它呢？
|
||||
|
||||
实际上，“看上去随机”是现存大多数密码学算法的更集。如果你观察一个密码学 hash 的输出，它得和随机的字符串不可区分，密码学家才会认可这个算法。如果你生成一个块加密，它的输出（在你不知道密钥的情况下）也必须和随机数据不可区分才行。
|
||||
实际上，“看上去随机”是现存大多数密码学基础组件的基本要求。如果你观察一个密码学哈希的输出，它一定得和随机的字符串不可区分，密码学家才会认可这个算法。如果你生成一个块加密，它的输出（在你不知道密钥的情况下）也必须和随机数据不可区分才行。
|
||||
|
||||
如果任何人能比暴力穷举要更有效地破解一个加密，比如它利用了某些 CSPRNG 伪随机的弱点，那这就又是老一套了：一切都废了，也别谈后面的了。块加密，hash，一切都是基于某个数学算法，比如 CSPRNG。所以别害怕，到头来都一样。
|
||||
如果任何人能比暴力穷举要更有效地破解一个加密，比如它利用了某些 CSPRNG 伪随机的弱点，那这就又是老一套了：一切都废了，也别谈后面的了。块加密、哈希，一切都是基于某个数学算法，比如 CSPRNG。所以别害怕，到头来都一样。
|
||||
|
||||
### 那熵池快空了的情况呢？
|
||||
|
||||
毫无影响。
|
||||
|
||||
加密算法的根基建立在攻击者不能预测输出上，只要最一开始有足够的随机性（熵）就行了。一般的下限是 256 bits，不需要更多了。
|
||||
加密算法的根基建立在攻击者不能预测输出上，只要最一开始有足够的随机性（熵）就行了。一般的下限是 256 位，不需要更多了。
|
||||
|
||||
介于我们一直在很随意的使用“熵”这个概念，我用 bits 来量化随机性希望读者不要太在意细节。像我们之前讨论的那样，内核的随机数生成器甚至没法精确地知道进入系统的熵的量。只有一个预估。而且这个预估的准确性到底怎么样也没人知道。
|
||||
It doesn't matter.
|
||||
介于我们一直在很随意的使用“熵”这个概念，我用“位”来量化随机性希望读者不要太在意细节。像我们之前讨论的那样，内核的随机数生成器甚至没法精确地知道进入系统的熵的量。只有一个预估。而且这个预估的准确性到底怎么样也没人知道。
|
||||
|
||||
### 重新选种
|
||||
|
||||
但如果熵这么不重要，为什么还要有新的熵一直被收进随机数生成器里呢？
|
||||
|
||||
djb [提到][4] 太多的熵甚至可能会起到反效果。
|
||||
> djb [提到][4] 太多的熵甚至可能会起到反效果。
|
||||
|
||||
首先，一般不会这样。如果你有很多随机性可以拿来用，用就对了！
|
||||
|
||||
@@ -189,92 +191,90 @@ djb [提到][4] 太多的熵甚至可能会起到反效果。
|
||||
|
||||
你已经凉了，因为攻击者可以计算出所有未来会被输出的随机数了。
|
||||
|
||||
但是，如果不断有新的熵被混进系统，那内部状态会在一次变得随机起来。所以随机数生成器被设计成这样有些“自愈”能力。
|
||||
但是，如果不断有新的熵被混进系统，那内部状态会再一次变得随机起来。所以随机数生成器被设计成这样有些“自愈”能力。
|
||||
|
||||
但这是在给内部状态引入新的熵，这和阻塞输出没有任何关系。
|
||||
|
||||
|
||||
### random 和 urandom 的 man 页面
|
||||
|
||||
这两个 man 页面在吓唬程序员方面很有建树：
|
||||
|
||||
> 从 /dev/urandom 读取数据不会因为需要更多熵而阻塞。这样的结果是，如果熵池里没有足够多的熵，取决于驱动使用的算法，返回的数值在理论上有被密码学攻击的可能性。发动这样攻击的步骤并没有出现在任何公开文献当中，但这样的攻击从理论上讲是可能存在的。如果你的应用担心这类情况，你应该使用 /dev/random。
|
||||
> 从 `/dev/urandom` 读取数据不会因为需要更多熵而阻塞。这样的结果是，如果熵池里没有足够多的熵，取决于驱动使用的算法，返回的数值在理论上有被密码学攻击的可能性。发动这样攻击的步骤并没有出现在任何公开文献当中，但这样的攻击从理论上讲是可能存在的。如果你的应用担心这类情况，你应该使用 `/dev/random`。
|
||||
|
||||
没有“公开的文献”描述，但是 NSA 的小卖部里肯定卖这种攻击手段是吧？如果你真的真的很担心（你应该很担心），那就用 /dev/random 然后所有问题都没了？
|
||||
>> 实际上已经有 `/dev/random` 和 `/dev/urandom` 的 Linux 内核 man 页面的更新版本。不幸的是，随便一个网络搜索出现我在结果顶部的仍然是旧的、有缺陷的版本。此外，许多 Linux 发行版仍在发布旧的 man 页面。所以不幸的是，这一节需要在这篇文章中保留更长的时间。我很期待删除这一节！
|
||||
|
||||
然而事实是，可能什么情报局有这种攻击，或者什么邪恶黑客组织找到了方法。但如果我们就直接假设这种攻击一定存在也是不合理的。
|
||||
没有“公开的文献”描述，但是 NSA 的小卖部里肯定卖这种攻击手段是吧？如果你真的真的很担心（你应该很担心），那就用 `/dev/random` 然后所有问题都没了？
|
||||
|
||||
而且就算你想给自己一个安心，我要给你泼个冷水：AES，SHA-3 或者其他什么常见的加密算法也没有“公开文献记述”的攻击手段。难道你也不用这几个加密算法了？这显然是可笑的。
|
||||
然而事实是，可能某个什么情报局有这种攻击，或者某个什么邪恶黑客组织找到了方法。但如果我们就直接假设这种攻击一定存在也是不合理的。
|
||||
|
||||
我们在回到 man 页面说：“使用 /dev/random”。我们已经知道了，虽然 /dev/urandom 不阻塞，但是它的随机数和 /dev/random 都是从同一个 CSPRNG 里来的。
|
||||
而且就算你想给自己一个安心，我要给你泼个冷水：AES、SHA-3 或者其它什么常见的加密算法也没有“公开文献记述”的攻击手段。难道你也不用这几个加密算法了？这显然是可笑的。
|
||||
|
||||
如果你真的需要信息论理论上安全的随机数（你不需要的相信我），那才有可能成为唯一一个你需要等足够熵进入 CSPRNG 的理由。而且你也不能用 /dev/random。
|
||||
我们在回到 man 页面说：“使用 `/dev/random`”。我们已经知道了，虽然 `/dev/urandom` 不阻塞，但是它的随机数和 `/dev/random` 都是从同一个 CSPRNG 里来的。
|
||||
|
||||
如果你真的需要信息论理论上安全的随机数（你不需要的，相信我），那才有可能成为唯一一个你需要等足够熵进入 CSPRNG 的理由。而且你也不能用 `/dev/random`。
|
||||
|
||||
man 页面有毒，就这样。但至少它还稍稍挽回了一下自己：
|
||||
> 如果你不确定该用 /dev/random 还是 /dev/urandom ，那你可能应该用后者。通常来说，除了需要长期使用的 GPG/SSL/SSH 密钥以外，你总该使用/dev/urandom 。
|
||||
|
||||
行。我觉得没必要，但如果你真的要用 /dev/random 来生成 “长期使用的密钥”，用就是了也没人拦着！你可能需要等几秒钟或者敲几下键盘来增加熵，但没什么问题。
|
||||
> 如果你不确定该用 `/dev/random` 还是 `/dev/urandom` ，那你可能应该用后者。通常来说，除了需要长期使用的 GPG/SSL/SSH 密钥以外，你总该使用`/dev/urandom` 。
|
||||
|
||||
>> 该手册页的[当前更新版本](http://man7.org/linux/man-pages/man4/random.4.html)毫不含糊地说：
|
||||
|
||||
>> `/dev/random` 接口被认为是遗留接口，并且 `/dev/urandom` 在所有用例中都是首选和足够的，除了在启动早期需要随机性的应用程序；对于这些应用程序，必须替代使用 `getrandom(2)`，因为它将阻塞，直到熵池初始化完成。
|
||||
|
||||
行。我觉得没必要，但如果你真的要用 `/dev/random` 来生成 “长期使用的密钥”，用就是了也没人拦着！你可能需要等几秒钟或者敲几下键盘来增加熵，但这没什么问题。
|
||||
|
||||
但求求你们，不要就因为“你想更安全点”就让连个邮件服务器要挂起半天。
|
||||
|
||||
### 正道
|
||||
|
||||
本篇文章里的观点显然在互联网上是“小众”的。但如果问问一个真正的密码学家，你很难找到一个认同阻塞 /dev/random 的人。
|
||||
本篇文章里的观点显然在互联网上是“小众”的。但如果问问一个真正的密码学家，你很难找到一个认同阻塞 `/dev/random` 的人。
|
||||
|
||||
比如我们看看 [Daniel Bernstein][5] djb：
|
||||
比如我们看看 [Daniel Bernstein][5]（即著名的 djb）的看法：
|
||||
|
||||
> 我们密码学家对这种胡乱迷信行为表示不负责。你想想，写 /dev/random man 页面的人好像同时相信：
|
||||
> 我们密码学家对这种胡乱迷信行为表示不负责。你想想，写 `/dev/random` man 页面的人好像同时相信：
|
||||
>
|
||||
> * (1) 我们不知道如何用一个 256-bit 长的 /dev/random 的输出来生成一个无限长的随机密钥串流（这是我们需要 /dev/urandom 吐出来的），但与此同时
|
||||
> * (1) 我们不知道如何用一个 256 位长的 `/dev/random` 的输出来生成一个无限长的随机密钥串流（这是我们需要 `/dev/urandom` 吐出来的），但与此同时
|
||||
> * (2) 我们却知道怎么用单个密钥来加密一条消息（这是 SSL，PGP 之类干的事情）
|
||||
>
|
||||
>
|
||||
|
||||
>
|
||||
> 对密码学家来说这甚至都不好笑了
|
||||
|
||||
|
||||
|
||||
或早 [Thomas Pornin][6]，他也是我在 stackexchange 上见过最乐于助人的一位：
|
||||
或者 [Thomas Pornin][6] 的看法，他也是我在 stackexchange 上见过最乐于助人的一位：
|
||||
|
||||
> 简单来说，是的。展开说，答案还是一样。/dev/urandom 生成的数据可以说和真随机完全无法区分，至少在现有科技水平下。使用比 /dev/urandom “更好的“随机性毫无意义，除非你在使用极为罕见的“信息论安全”的加密算法。这肯定不是你的情况，不然你早就说了。
|
||||
> 简单来说，是的。展开说，答案还是一样。`/dev/urandom` 生成的数据可以说和真随机完全无法区分，至少在现有科技水平下。使用比 `/dev/urandom` “更好的“随机性毫无意义，除非你在使用极为罕见的“信息论安全”的加密算法。这肯定不是你的情况，不然你早就说了。
|
||||
>
|
||||
> urandom 的 man 页面多多少少有些误导人，或者干脆可以说是错的——特别是当它说 /dev/urandom 会“用完熵”以及 “/dev/random 是更好的”那几句话；
|
||||
> urandom 的 man 页面多多少少有些误导人，或者干脆可以说是错的——特别是当它说 `/dev/urandom` 会“用完熵”以及 “`/dev/random` 是更好的”那几句话；
|
||||
|
||||
|
||||
|
||||
或者 [Thomas Ptacek][7]，他不设计密码算法或者密码学系统，但他是一家名声在外的安全咨询公司的创始人，这家公司负责很多渗透和破解烂密码学算法的测试：
|
||||
或者 [Thomas Ptacek][7] 的看法，他不设计密码算法或者密码学系统，但他是一家名声在外的安全咨询公司的创始人，这家公司负责很多渗透和破解烂密码学算法的测试：
|
||||
|
||||
> 用 urandom。用 urandom。用 urandom。用 urandom。用 urandom。
|
||||
|
||||
|
||||
|
||||
### 没有完美
|
||||
|
||||
/dev/urandom 不是完美的，问题分两层：
|
||||
`/dev/urandom` 不是完美的，问题分两层：
|
||||
|
||||
在 Linux 上，不像 FreeBSD，/dev/urandom 永远不阻塞。记得安全性取决于某个最一开始决定的随机性？种子？
|
||||
在 Linux 上，不像 FreeBSD，`/dev/urandom` 永远不阻塞。记得安全性取决于某个最一开始决定的随机性？种子？
|
||||
|
||||
Linux 的 /dev/urandom 会很乐意给你吐点不怎么随机的随机数，甚至在内核有机会收集一丁点熵之前。什么时候有这种情况？当你系统刚刚启动的时候。
|
||||
Linux 的 `/dev/urandom` 会很乐意给你吐点不怎么随机的随机数，甚至在内核有机会收集一丁点熵之前。什么时候有这种情况？当你系统刚刚启动的时候。
|
||||
|
||||
FreeBSD 的行为更正确点：/dev/random 和 /dev/urandom 是一样的，在系统启动的时候 /dev/random 会阻塞到有足够的熵为止，然后他们都再也不阻塞了。
|
||||
FreeBSD 的行为更正确点：`/dev/random` 和 `/dev/urandom` 是一样的，在系统启动的时候 `/dev/random` 会阻塞到有足够的熵为止，然后它们都再也不阻塞了。
|
||||
|
||||
与此同时 Linux 实行了一个新的 syscall，最早由 OpenBSD 引入叫 getentrypy(2)，在 Linux 下这个叫 getrandom(2)。这个 syscall 有着上述正确的行为：阻塞到有足够的熵为止，然后再也不阻塞了。当然，这是个 syscall，而不是一个字节设备（译者：指不在 /dev/ 下），所以它在 shell 或者别的脚本语言里没那么容易获取。这个 syscall 自 Linux 3.17 起存在。
|
||||
> 与此同时 Linux 实行了一个新的<ruby>系统调用<rt>syscall</rt></ruby>，最早由 OpenBSD 引入叫 `getentrypy(2)`，在 Linux 下这个叫 `getrandom(2)`。这个系统调用有着上述正确的行为：阻塞到有足够的熵为止，然后再也不阻塞了。当然，这是个系统调用，而不是一个字节设备（LCTT 译注：指不在 `/dev/` 下），所以它在 shell 或者别的脚本语言里没那么容易获取。这个系统调用 自 Linux 3.17 起存在。
|
||||
|
||||
在 Linux 上其实这个问题不太大，因为 Linux 发行版会在启动的过程中储蓄一点随机数（这发生在已经有一些熵之后，因为启动程序不会在按下电源的一瞬间就开始运行）到一个种子文件，以便系统下次启动的时候读取。所以每次启动的时候系统都会从上一次会话里带一点随机性过来。
|
||||
在 Linux 上其实这个问题不太大，因为 Linux 发行版会在启动的过程中储蓄一点随机数（这发生在已经有一些熵之后，因为启动程序不会在按下电源的一瞬间就开始运行）到一个种子文件中，以便系统下次启动的时候读取。所以每次启动的时候系统都会从上一次会话里带一点随机性过来。
|
||||
|
||||
显然这比不上在关机脚本里写入一些随机种子，因为这样的显然就有更多熵可以操作了。但这样做显而易见的好处就是它不关心系统是不是正确关机了，比如可能你系统崩溃了。
|
||||
显然这比不上在关机脚本里写入一些随机种子，因为这样的显然就有更多熵可以操作了。但这样做显而易见的好处就是它不用关心系统是不是正确关机了，比如可能你系统崩溃了。
|
||||
|
||||
而且这种做法在你真正第一次启动系统的时候也没法帮你随机，不过好在系统安装器一般会写一个种子文件，所以基本上问题不大。
|
||||
|
||||
虚拟机是另外一层问题。因为用户喜欢克隆他们，或者恢复到某个之前的状态。这种情况下那个种子文件就帮不到你了。
|
||||
虚拟机是另外一层问题。因为用户喜欢克隆它们，或者恢复到某个之前的状态。这种情况下那个种子文件就帮不到你了。
|
||||
|
||||
但解决方案依然和用 /dev/random 没关系，而是你应该正确的给每个克隆或者恢复的的镜像重新生成种子文件，之类的。
|
||||
但解决方案依然和用 `/dev/random` 没关系，而是你应该正确的给每个克隆或者恢复的镜像重新生成种子文件。
|
||||
|
||||
### 太长不看;
|
||||
|
||||
别问，问就是用 /dev/urandom !
|
||||
### 太长不看
|
||||
|
||||
别问，问就是用 `/dev/urandom` !
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
@@ -282,14 +282,14 @@ via: https://www.2uo.de/myths-about-urandom/
|
||||
|
||||
作者：[Thomas Hühn][a]
|
||||
译者：[Moelf](https://github.com/Moelf)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
校对：[wxy](https://github.com/wxy)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:https://www.2uo.de/
|
||||
[1]:https://www.2uo.de/myths-about-urandom/structure-no.png
|
||||
[2]:https://www.2uo.de/myths-about-urandom/structure-yes.png
|
||||
[3]:https://www.2uo.de/myths-about-urandom/structure-new.png
|
||||
[1]:https://www.2uo.de/_media/wiki:structure-no.png
|
||||
[2]:https://www.2uo.de/_media/wiki:structure-yes.png
|
||||
[3]:https://www.2uo.de/_media/wiki:structure-new.png
|
||||
[4]:http://blog.cr.yp.to/20140205-entropy.html
|
||||
[5]:http://www.mail-archive.com/cryptography@randombit.net/msg04763.html
|
||||
[6]:http://security.stackexchange.com/questions/3936/is-a-rand-from-dev-urandom-secure-for-a-login-key/3939#3939
|
||||
|
||||
@@ -1,172 +0,0 @@
|
||||
Ubuntu 和其他 Linux 发行版上的12个最好的 GTK 主题
|
||||
======
|
||||
**简言之:让我们看一看一些漂亮的 GTK 主题，你可能不仅在 Ubuntu 上使用，在其它使用 GNOME 的 Linux 发行版上也使用。**
|
||||
|
||||
我们中的一些狭义上地使用 Ubuntu，从 Unity 移到 Gnome 作为默认桌面环境使制作主题和自定义比以前更简单。Gnome 有相当大的调整社区，并且这里不缺少来供用户来选择的极好的 GTK 主题。考虑到这点，我继续前进并在最近几个月偶然找到一些我非常喜欢的主题。我相信这些是给予你能找到的一些最好体验。
|
||||
|
||||
### Ubuntu 和其它 Linux 发行版的最好的主题
|
||||
|
||||
这不是一个详细清单，可能不包括一些你已经使用和喜欢的主题，但愿，你找到至少一个你喜爱的你还不知道的主题。所有出现的主题能工作在一些 Gnome 3 计划上，Ubuntu 或其它。我丢失一些屏幕截屏，所以我从官方网站上获取图片。
|
||||
|
||||
在这里列出的主题没有特别的次序。
|
||||
|
||||
但是，在你看最好的 GNOME 主题前，你应该学习 [如何在 Ubuntu GNOME 中安装主题][1]。
|
||||
|
||||
#### 1\. Arc-Ambiance
|
||||
|
||||
![][2]
|
||||
|
||||
Arc 和 Arc 变体主题现在已经出现相当长的时间，并广泛地被认为是你可以找到的最好的一些主题。在这个示例中，我选择 Arc-Ambiance ，因为它的现代化在 Ubuntu 上呈现默认周围环境主题。
|
||||
|
||||
我是 Arc 主题和默认周围环境主题的粉丝,所以不用说，当我遇到一个融合最好的两者世界的主题，我被惊出一口气。如果你是 Arc 主题的一个粉丝，但不是这个的特别粉丝，Gnome 外貌有其它大量的选项，这将非常适合你的体验。
|
||||
|
||||
[Arc-Ambiance 主题][3]
|
||||
|
||||
#### 2\. Adapta Colorpack
|
||||
|
||||
![][4]
|
||||
|
||||
Adapta 主题是我最喜欢的我可能找到的扁平主题之一。像 Arc 一样，Adapata 被很多 linux 用户广泛的采用。我选择这个颜色包，因为一次下载你有数个选项来选择。事实上，这有19个来选择。是的。你读的这些是正确的。19！
|
||||
|
||||
所以，如果你是一个我们今天看到很多的扁平/素材设计语言的粉丝，那么，在这个主题包中最可能有一个满足你的变体。
|
||||
|
||||
[Adapta Colorpack 主题][5]
|
||||
|
||||
#### 3\. Numix Collection
|
||||
|
||||
![][6]
|
||||
|
||||
啊，Numix! 哦，这些年我们一起度过！对于我们中的一些，这已经是我们最近几年的桌面的主题，你必定在一些时间点上偶然发现 Numix 主题或图标包。Numix 很可能是我爱上的最现代的 Linux 主题，现在我仍然爱它 。并且在这些年后，它仍然不失它的魅力。
|
||||
|
||||
灰色色调贯穿主题，尤其是带有默认粉红高亮颜色，制作一个真正地清洁的和完整的体验。你可能很难找到一个像 Numix 一样精美的主题包。在这个作品中，你有很多选项来选择，所以，来疯狂吧！
|
||||
|
||||
[Numix Collection 主题][7]
|
||||
|
||||
#### 4\. Hooli
|
||||
|
||||
![][8]
|
||||
|
||||
Hooli 现在是一个过时的主题，但是我仅最近偶然探测到它。我是大多数扁平主题的粉丝，但是经常远离素材设计语言主题。Hooli，像 Adapta，从这些设计语言中得到想法，但是在某种程度上做它，我认为使它脱离其它事物。绿色高亮颜色是我对这个主题最喜欢的部分之一，并且，它在非过于强烈对比的整个主题上做了很好的工作。
|
||||
|
||||
[Hooli 主题][9]
|
||||
|
||||
#### 5\. Arrongin/Telinkrin
|
||||
|
||||
![][10]
|
||||
|
||||
Bonus: 两个主题在一个中！并且它们是在主题领域中的相对新的竞争者。它们都从 Ubuntu 快完成的 “[communitheme][11]” 得到想法，并带它到你今天的桌面。我能在找到两者给予的仅有的真正不同点是颜色。Arrongin 是以 Ubuntu-esq 橙色颜色为中心，然而 Telinkrin 使用一个更细长的 KDE Breeze-esq 蓝色，我个人更喜欢蓝色，但是两者都是极好的选项！
|
||||
|
||||
[Arrongin/Telinkrin 主题][12]
|
||||
|
||||
#### 6\. Gnome-osx
|
||||
|
||||
![][13]
|
||||
|
||||
我不得不承认，通常，当我看到一个主题有 “osx” 或一些在标题中类似的事，我不期望很多。大多数受苹果启发的主题看起来多少有共同点，我真不能找到一个使用它们的原因。这里有两个主题，我想能打破这个模式：在这里我们有 Arc-osc 主题和 Gnome-osx 主题。
|
||||
|
||||
我喜欢 Gnome-osx 主题的原因是因为它在 Gnome 桌面上看起来真实。它很好地做好混合到桌面环境中工作，而不太扁平。 所以，对于你们中一些喜欢轻微地较少扁平主题的人，如果你喜欢红色，黄色，和用于关闭，最小化，和做大化按钮的绿色按钮方案，这个主题对你更优秀。
|
||||
|
||||
[Gnome-osx 主题][14]
|
||||
|
||||
#### 7\. Ultimate Maia
|
||||
|
||||
![][15]
|
||||
|
||||
有一段时间，我使用 Manjaro Gnome。尽管我已经返回到 Ubuntu，但是，我希望我可以携带的一个东西是 Manjaro 主题。如果你对 Manjaro 主题像我一样感觉相同，那么你是幸运的，因为你可以带它到一些你想的发行版，它在 Gnomes 上运行！
|
||||
|
||||
丰富的绿色颜色，Breeze-esq 关闭，最小化，最大化按钮，并且全面精美的主题时成为一个不可抗拒的选项。它甚至为你不是一个绿色的粉丝而提供一些其它颜色变体。但是，让我们成为真诚的…谁不是 Manjaro 绿色颜色的一个粉丝？
|
||||
|
||||
[Ultimate Maia 主题][16]
|
||||
|
||||
#### 8\. Vimix
|
||||
|
||||
![][17]
|
||||
|
||||
这是一个让我容易获得兴奋的主题。它是现代的，从 macOS 红色中，黄色，绿色按钮中拉出来的，而不是直接复制它们，并下调主题的活力色调，使之对大多数其它主题成为一个唯一可替换物。它带来三个黑暗色的变体和我们中大多数将找到我们喜欢的一些颜色。
|
||||
|
||||
[Vimix 主题][18]
|
||||
|
||||
#### 9\. Ant
|
||||
|
||||
![][19]
|
||||
|
||||
像 Vimix 一样，Ant 从 macOS 中按钮颜色吸引灵感，而不是直接复制样式。在哪里 Vimix 下调颜色选项，Ant 在我的System 76 Galago Pro 屏幕上添加一个看起来极好的丰富的颜色。三个主题选项之间的变体是相当激动人心的，虽然它可能不见得符合每个人的体验，它无疑是最适合我的。
|
||||
|
||||
[Ant 主题][20]
|
||||
|
||||
#### 10\. Flat Remix
|
||||
|
||||
![][21]
|
||||
|
||||
如果你还没有注意到这点，我对一些关注关闭，最小化、最大化按钮的人来说是一个傻瓜。Flat Remix 使用的颜色主题是一个我没有在其它一些地方看到过的，带有一个红色，蓝色，和橙色方式。添加这些到一个几乎看起来像一个混合 Arc 和 Adapta 的主题的上面，你有了 Flat Remix 。
|
||||
|
||||
我本人是一个暗选项的粉丝，但是亮的可替换物也是非常好的。因此，如果你喜欢巧妙的透明度，一个内聚的暗主题，以及这里和那里的一点颜色，Flat Remix 献给你。
|
||||
|
||||
[Flat Remix 主题][22]
|
||||
|
||||
#### 11\. Paper
|
||||
|
||||
![][23]
|
||||
|
||||
[Paper][24] 现在已经有一段时间。我记得第一次使用它在2014年。我可以说，在这点上，Paper 的图标包比 GTK 主题更出名，但是这不意味着它自身中的主题不是一个极好的选项。哪怕，我从一开始就爱慕 Paper 图标，我不能说，当我第一次尝试它的时候，我是一个忠实的 Paper 主题粉丝。
|
||||
|
||||
我深感喜欢鲜亮的颜色和开心的接近到一个被制作成一个非常合适的“不成熟”的体验主题。现在，几年后，Paper 已经在我心中长大，至少可以这样说这个主题采取的中心明亮的方法是我非常欣赏的一个。
|
||||
|
||||
[Paper 主题][25]
|
||||
|
||||
#### 12\. Pop
|
||||
|
||||
![][26]
|
||||
|
||||
Pop 在这个列表上是一个较新的提案。由在at [System 76][27] 上的人们创造，Pop GTK 主题 Adapta 主题的一个早期列表分叉，并带有一个匹配的图标包，图标包是先前提到的 Paper 图标包的一个分叉。
|
||||
|
||||
该主题在 System 76 宣布后不久就被宣布，它们被宣布在 [它们自己的发行版，][28] Pop!_OS 上。你可以读我的 [Pop!_OS 评论][29] 来了解过多。不用说，我认为 Pop 是一个极好的主题带有一个华丽的润饰并提供一种新鲜的感觉到一些 Gnome 桌面。
|
||||
|
||||
[Pop 主题][30]
|
||||
|
||||
#### 结束语
|
||||
|
||||
很明显，我们有比文中所描述主题更多的选择，但是这些大多是我在最近几月所使用的最完整的和最精良的主题。如果你认为我们错过一些你确实喜欢的主题或你确实不喜欢我在上面描述的主题，那么，在下面的评论区让我们知道，并分享为什么你认为你喜欢的主题更好！
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
通过: https://itsfoss.com/best-gtk-themes/
|
||||
|
||||
作者：[Phillip Prado][a]
|
||||
译者：[robsean](https://github.com/robsean)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
选题：[lujun9972](https://github.com/lujun9972)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:https://itsfoss.com/author/phillip/
|
||||
[1]:https://itsfoss.com/install-themes-ubuntu/
|
||||
[2]:https://itsfoss.com/wp-content/uploads/2018/03/arcambaince-300x225.png
|
||||
[3]:https://www.gnome-look.org/p/1193861/
|
||||
[4]:https://itsfoss.com/wp-content/uploads/2018/03/adapta-300x169.jpg
|
||||
[5]:https://www.gnome-look.org/p/1190851/
|
||||
[6]:https://itsfoss.com/wp-content/uploads/2018/03/numix-300x169.png
|
||||
[7]:https://www.gnome-look.org/p/1170667/
|
||||
[8]:https://itsfoss.com/wp-content/uploads/2018/03/hooli2-800x500.jpg
|
||||
[9]:https://www.gnome-look.org/p/1102901/
|
||||
[10]:https://itsfoss.com/wp-content/uploads/2018/03/AT-800x590.jpg
|
||||
[11]:https://itsfoss.com/ubuntu-community-theme/
|
||||
[12]:https://www.gnome-look.org/p/1215199/
|
||||
[13]:https://itsfoss.com/wp-content/uploads/2018/03/gosx-800x473.jpg
|
||||
[14]:https://www.opendesktop.org/s/Gnome/p/1171688/
|
||||
[15]:https://itsfoss.com/wp-content/uploads/2018/03/ultimatemaia-800x450.jpg
|
||||
[16]:https://www.opendesktop.org/s/Gnome/p/1193879/
|
||||
[17]:https://itsfoss.com/wp-content/uploads/2018/03/vimix-800x450.jpg
|
||||
[18]:https://www.gnome-look.org/p/1013698/
|
||||
[19]:https://itsfoss.com/wp-content/uploads/2018/03/ant-800x533.png
|
||||
[20]:https://www.opendesktop.org/p/1099856/
|
||||
[21]:https://itsfoss.com/wp-content/uploads/2018/03/flatremix-800x450.png
|
||||
[22]:https://www.opendesktop.org/p/1214931/
|
||||
[23]:https://itsfoss.com/wp-content/uploads/2018/04/paper-800x450.jpg
|
||||
[24]:https://itsfoss.com/install-paper-theme-linux/
|
||||
[25]:https://snwh.org/paper/download
|
||||
[26]:https://itsfoss.com/wp-content/uploads/2018/04/pop-800x449.jpg
|
||||
[27]:https://system76.com/
|
||||
[28]:https://itsfoss.com/system76-popos-linux/
|
||||
[29]:https://itsfoss.com/pop-os-linux-review/
|
||||
[30]:https://github.com/pop-os/gtk-theme/blob/master/README.md
|
||||
@@ -0,0 +1,287 @@
|
||||
Sensu 监控入门
|
||||
======
|
||||
|
||||
|
||||
Sensu 是一个开源基础设施和应用程序监控解决方案，它监控服务器、相关服务和应用程序健康状况，并通过第三方集成发送警报和通知。Sensu 用 Ruby 编写，可以使用 [RabbitMQ][1] 或 [Redis][2] 来处理消息，它使用 Redis 来存储数据。
|
||||
|
||||
如果你想以一种简单而有效的方式监控云基础设施，Sensu 是一个不错的选择。它可以与你组织已经使用的许多现代 DevOps 堆栈集成，比如 [Slack][3]、[HipChat][4 ] 或 [IRC][5]，它甚至可以用 [PagerDuty][6] 发送移动或寻呼机警报。
|
||||
|
||||
Sensu 的[模块化架构][7]意味着每个组件都可以安装在同一台服务器上或者在完全独立的机器上。
|
||||
|
||||
### 结构
|
||||
|
||||
Sensu 的主要通信机制是 `Transport`。每个 Sensu 组件必须连接到 `Transport` 才能相互发送消息。`Transport` 可以使用 RabbitMQ（在生产中推荐使用）或 Redis。
|
||||
|
||||
Sensu 服务器处理事件数据并采取行动。它注册客户端并使用过滤器、增变器和处理程序检查结果和监视事件。服务器向客户端发布检查说明，Sensu API 提供 RESTful API，提供对监控数据和核心功能的访问。
|
||||
|
||||
[Sensu 客户端][8]执行 Sensu 服务器安排的检查或本地检查定义。Sensu 使用数据存储（Redis）来保存所有的持久数据。最后，[Uchiwa][9] 是与 Sensu API 进行通信的 Web 界面。
|
||||
|
||||
![sensu_system.png][11]
|
||||
|
||||
### 安装 Sensu
|
||||
|
||||
#### 条件
|
||||
|
||||
* 一个 Linux 系统作为服务器节点（本文使用了 CentOS 7）
|
||||
* 要监控的一台或多台 Linux 机器（客户机）
|
||||
|
||||
#### 服务器侧
|
||||
|
||||
Sensu 需要安装 Redis。要安装 Redis，启用 EPEL 仓库：
|
||||
```
|
||||
$ sudo yum install epel-release -y
|
||||
|
||||
```
|
||||
|
||||
然后安装 Redis：
|
||||
```
|
||||
$ sudo yum install redis -y
|
||||
|
||||
```
|
||||
|
||||
修改 `/etc/redis.conf` 来禁用保护模式，监听每个地址并设置密码：
|
||||
```
|
||||
$ sudo sed -i 's/^protected-mode yes/protected-mode no/g' /etc/redis.conf
|
||||
|
||||
$ sudo sed -i 's/^bind 127.0.0.1/bind 0.0.0.0/g' /etc/redis.conf
|
||||
|
||||
$ sudo sed -i 's/^# requirepass foobared/requirepass password123/g' /etc/redis.conf
|
||||
|
||||
```
|
||||
|
||||
启用并启动 Redis 服务：
|
||||
```
|
||||
$ sudo systemctl enable redis
|
||||
$ sudo systemctl start redis
|
||||
```
|
||||
|
||||
Redis 现在已经安装并准备好被 Sensu 使用。
|
||||
|
||||
现在让我们来安装 Sensu。
|
||||
|
||||
首先，配置 Sensu 仓库并安装软件包：
|
||||
```
|
||||
$ sudo tee /etc/yum.repos.d/sensu.repo << EOF
|
||||
[sensu]
|
||||
name=sensu
|
||||
baseurl=https://sensu.global.ssl.fastly.net/yum/\$releasever/\$basearch/
|
||||
gpgcheck=0
|
||||
enabled=1
|
||||
EOF
|
||||
|
||||
$ sudo yum install sensu uchiwa -y
|
||||
```
|
||||
|
||||
让我们为 Sensu 创建最简单的配置文件：
|
||||
```
|
||||
$ sudo tee /etc/sensu/conf.d/api.json << EOF
|
||||
{
|
||||
"api": {
|
||||
"host": "127.0.0.1",
|
||||
"port": 4567
|
||||
}
|
||||
}
|
||||
EOF
|
||||
```
|
||||
|
||||
然后，配置 `sensu-api` 在本地主机上使用端口 4567 监听：
|
||||
```
|
||||
$ sudo tee /etc/sensu/conf.d/redis.json << EOF
|
||||
{
|
||||
"redis": {
|
||||
"host": "<IP of server>",
|
||||
"port": 6379,
|
||||
"password": "password123"
|
||||
}
|
||||
}
|
||||
EOF
|
||||
|
||||
|
||||
$ sudo tee /etc/sensu/conf.d/transport.json << EOF
|
||||
{
|
||||
"transport": {
|
||||
"name": "redis"
|
||||
}
|
||||
}
|
||||
EOF
|
||||
```
|
||||
|
||||
在这两个文件中，我们将 Sensu 配置为使用 Redis 作为传输机制，还有 Reids 监听的地址。客户端需要直接连接到传输机制。每台客户机都需要这两个文件。
|
||||
```
|
||||
$ sudo tee /etc/sensu/uchiwa.json << EOF
|
||||
{
|
||||
"sensu": [
|
||||
{
|
||||
"name": "sensu",
|
||||
"host": "127.0.0.1",
|
||||
"port": 4567
|
||||
}
|
||||
],
|
||||
"uchiwa": {
|
||||
"host": "0.0.0.0",
|
||||
"port": 3000
|
||||
}
|
||||
}
|
||||
EOF
|
||||
```
|
||||
|
||||
在这个文件中，我们配置 `Uchiwa` 监听端口 3000 上的每个地址（0.0.0.0）。我们还配置 `Uchiwa` 使用 `sensu-api`（已配置好）。
|
||||
|
||||
出于安全原因，更改刚刚创建的配置文件的所有者：
|
||||
```
|
||||
$ sudo chown -R sensu:sensu /etc/sensu
|
||||
```
|
||||
|
||||
启用并启动 Sensu 服务：
|
||||
```
|
||||
$ sudo systemctl enable sensu-server sensu-api sensu-client
|
||||
$ sudo systemctl start sensu-server sensu-api sensu-client
|
||||
$ sudo systemctl enable uchiwa
|
||||
$ sudo systemctl start uchiwa
|
||||
```
|
||||
|
||||
尝试访问 `Uchiwa` 网站：http://<服务器的 IP 地址>:3000
|
||||
|
||||
对于生产环境，建议运行 RabbitMQ 集群作为 Transport 而不是 Redis（虽然 Redis 集群也可以用于生产），运行多个 Sensu 服务器实例和 API 实例，以实现负载均衡和高可用性。
|
||||
|
||||
Sensu 现在安装完成，让我们来配置客户端。
|
||||
|
||||
#### 客户端侧
|
||||
|
||||
要添加一个新客户端，你需要通过创建 `/etc/yum.repos.d/sensu.repo` 文件在客户机上启用 Sensu 仓库。
|
||||
```
|
||||
$ sudo tee /etc/yum.repos.d/sensu.repo << EOF
|
||||
[sensu]
|
||||
name=sensu
|
||||
baseurl=https://sensu.global.ssl.fastly.net/yum/\$releasever/\$basearch/
|
||||
gpgcheck=0
|
||||
enabled=1
|
||||
EOF
|
||||
```
|
||||
|
||||
启用仓库后，安装 Sensu：
|
||||
```
|
||||
$ sudo yum install sensu -y
|
||||
```
|
||||
|
||||
要配置 `sensu-client`，创建在服务器中相同的 `redis.json` 和 `transport.json`，还有 `client.json` 配置文件：
|
||||
```
|
||||
$ sudo tee /etc/sensu/conf.d/client.json << EOF
|
||||
{
|
||||
"client": {
|
||||
"name": "rhel-client",
|
||||
"environment": "development",
|
||||
"subscriptions": [
|
||||
"frontend"
|
||||
]
|
||||
}
|
||||
}
|
||||
EOF
|
||||
```
|
||||
|
||||
在 `name` 字段中，指定一个名称来标识此客户机（通常是主机名）。`environment` 字段可以帮助你过滤，订阅定义客户机将执行哪些监视检查。
|
||||
|
||||
最后，启用并启动服务并检查 `Uchiwa`，因为客户机会自动注册：
|
||||
```
|
||||
$ sudo systemctl enable sensu-client
|
||||
$ sudo systemctl start sensu-client
|
||||
```
|
||||
|
||||
### Sensu 检查
|
||||
|
||||
Sensu 检查有两个组件：一个插件和一个定义。
|
||||
|
||||
Sensu 与 [Nagios 检查插件规范][12]兼容，因此无需修改即可使用针对 Nagios 的任何检查。检查是可执行文件，由 Sensu 客户机运行。
|
||||
|
||||
检查定义让 Sensu 知道如何、在哪以及何时运行插件。
|
||||
|
||||
#### 客户端侧
|
||||
|
||||
让我们在客户机上安装一个检查插件。请记住，此插件将在客户机上执行。
|
||||
|
||||
启用 EPEL 并安装 `nagios-plugins-http` :
|
||||
```
|
||||
$ sudo yum install -y epel-release
|
||||
$ sudo yum install -y nagios-plugins-http
|
||||
```
|
||||
|
||||
现在让我们通过手动执行它来研究这个插件。尝试检查客户机上运行的 Web 服务器的状态。它应该会失败，因为我们并没有运行 Web 服务器：
|
||||
```
|
||||
$ /usr/lib64/nagios/plugins/check_http -I 127.0.0.1
|
||||
connect to address 127.0.0.1 and port 80: Connection refused
|
||||
HTTP CRITICAL - Unable to open TCP socket
|
||||
```
|
||||
|
||||
不出所料，它失败了。检查执行的返回值：
|
||||
```
|
||||
$ echo $?
|
||||
2
|
||||
|
||||
```
|
||||
|
||||
Nagios 检查插件规范定义了插件执行的四个返回值：
|
||||
|
||||
| **Plugin return code** | **State** |
|
||||
|------------------------|-----------|
|
||||
| 0 | OK |
|
||||
| 1 | WARNING |
|
||||
| 2 | CRITICAL |
|
||||
| 3 | UNKNOWN |
|
||||
|
||||
有了这些信息，我们现在可以在服务器上创建检查定义。
|
||||
|
||||
#### 服务器侧
|
||||
|
||||
在服务器机器上，创建 `/etc/sensu/conf.d/check_http.json` 文件：
|
||||
```
|
||||
{
|
||||
"checks": {
|
||||
"check_http": {
|
||||
"command": "/usr/lib64/nagios/plugins/check_http -I 127.0.0.1",
|
||||
"interval": 10,
|
||||
"subscribers": [
|
||||
"frontend"
|
||||
]
|
||||
}
|
||||
}
|
||||
}
|
||||
```
|
||||
|
||||
在 `command ` 字段中，使用我们之前测试过的命令。`Interval` 会告诉 Sensu 这个检查的频率，以秒为单位。最后，`subscribers` 将定义执行检查的客户机。
|
||||
|
||||
重新启动 sensu-api 和 sensu-server 并确认新检查在 Uchiwa 中可用。
|
||||
|
||||
```
|
||||
$ sudo systemctl restart sensu-api sensu-server
|
||||
```
|
||||
|
||||
### 接下来
|
||||
|
||||
Sensu 是一个功能强大的工具，本文只简要介绍它可以干什么。参阅[文档][13]了解更多信息，访问 Sensu 网站了解有关 [Sensu 社区][14]的更多信息。
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/18/8/getting-started-sensu-monitoring-solution
|
||||
|
||||
作者：[Michael Zamot][a]
|
||||
选题：[lujun9972](https://github.com/lujun9972)
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:https://opensource.com/users/mzamot
|
||||
[1]:https://www.rabbitmq.com/
|
||||
[2]:https://redis.io/topics/config
|
||||
[3]:https://slack.com/
|
||||
[4]:https://en.wikipedia.org/wiki/HipChat
|
||||
[5]:http://www.irc.org/
|
||||
[6]:https://www.pagerduty.com/
|
||||
[7]:https://docs.sensu.io/sensu-core/1.4/overview/architecture/
|
||||
[8]:https://docs.sensu.io/sensu-core/1.4/installation/install-sensu-client/
|
||||
[9]:https://uchiwa.io/#/
|
||||
[10]:/file/406576
|
||||
[11]:https://opensource.com/sites/default/files/uploads/sensu_system.png (sensu_system.png)
|
||||
[12]:https://assets.nagios.com/downloads/nagioscore/docs/nagioscore/4/en/pluginapi.html
|
||||
[13]:https://docs.sensu.io/
|
||||
[14]:https://sensu.io/community
|
||||
@@ -0,0 +1,91 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: (geekpi)
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (Enjoy Netflix? You Should Thank FreeBSD)
|
||||
[#]: via: (https://itsfoss.com/netflix-freebsd-cdn/)
|
||||
[#]: author: (Abhishek Prakash https://itsfoss.com/author/abhishek/)
|
||||
|
||||
享受 Netflix 么？你应该感谢 FreeBSD
|
||||
======
|
||||
|
||||
Netflix 是世界上最受欢迎的流媒体服务之一。
|
||||
|
||||
但你已经知道了。不是吗？
|
||||
|
||||
你可能不知道的是 Netflix 使用 [FreeBSD][1] 向你提供内容。
|
||||
|
||||
是的。Netflix 依靠 FreeBSD 来构建其内部内容交付网络 （CDN）。
|
||||
|
||||
[CDN][2] 是一组位于世界各地的服务器。它主要用于向终端用户分发像图像和视频这样的“大文件”。
|
||||
|
||||
Netflix 没有选择商业 CDN 服务，而是建立了自己的内部 CDN，名为 [Open Connect][3]。
|
||||
|
||||
Open Connect 使用[自定义硬件][4]，Open Connect Appliance。你可以在下面的图片中看到它。它可以处理 40Gb/s 的数据，存储容量为 248 TB。
|
||||
|
||||
![Netflix’s Open Connect Appliance runs FreeBSD][5]
|
||||
|
||||
Netflix 免费为合格的互联网服务提供商 （ISP） 提供 Open Connect Appliance。通过这种方式，大量的 Netflix 流量得到了本地化，ISP 可以更高效地提供 Netflix 内容。
|
||||
|
||||
Open Connect Appliance 运行在 FreeBSD 操作系统上，并且[几乎完全运行开源软件][6]。
|
||||
|
||||
### Open Connect 使用 FreeBSD “头”
|
||||
|
||||
![][7]
|
||||
|
||||
你或许会期望 Netflix 在这样一个关键基础设施上使用 FreeBSD 的稳定版本，但 Netflix 会跟踪 [FreeBSD 头/当前版本][8]。Netflix 表示，跟踪“头”让他们“保持前瞻性，专注于创新”。
|
||||
|
||||
以下是 Netflix 跟踪 FreeBSD 的好处：
|
||||
|
||||
* 更快的功能迭代
|
||||
* 更快地使用 FreeBSD 的新功能
|
||||
* 更快的 bug 修复
|
||||
* 实现协作
|
||||
* 尽量减少合并冲突
|
||||
* 摊销合并“成本”
|
||||
|
||||
|
||||
|
||||
> 运行 FreeBSD “head” 可以让我们非常高效地向用户分发大量数据，同时保持高速的功能开发。
|
||||
>
|
||||
> Netflix
|
||||
|
||||
请记得，甚至[谷歌也使用 Debian][9] 测试版而不是 Debian 稳定版。也许这些企业更喜欢最先进的功能。
|
||||
|
||||
与谷歌一样，Netflix 也计划向上游提供代码。这应该有助于 FreeBSD 和其他基于 FreeBSD 的 BSD 发行版。
|
||||
|
||||
那么 Netflix 用 FreeBSD 实现了什么？以下是一些统计数据：
|
||||
|
||||
> 使用 FreeBSD 和商业硬件，我们在 16 核 2.6GHz CPU 上使用约 55％ 的 CPU，实现了 90 Gb/s 的 TLS 加密连接，。
|
||||
>
|
||||
> Netflix
|
||||
|
||||
如果你想了解更多关于 Netflix 和 FreeBSD 的信息，可以参考 [FOSDEM 的这个演示文稿][10]。你还可以在[这里][11]观看演示文稿的视频。
|
||||
|
||||
目前，大型企业主要依靠 Linux 来实现其服务器基础架构，但 Netflix 已经信任了 BSD。这对 BSD 社区来说是一件好事，因为如果像 Netflix 这样的行业领导者重视 BSD，那么其他人也可以跟上。你怎么看？
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://itsfoss.com/netflix-freebsd-cdn/
|
||||
|
||||
作者：[Abhishek Prakash][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[geekpi](https://github.com/geekpi)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://itsfoss.com/author/abhishek/
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://www.freebsd.org/
|
||||
[2]: https://www.cloudflare.com/learning/cdn/what-is-a-cdn/
|
||||
[3]: https://openconnect.netflix.com/en/
|
||||
[4]: https://openconnect.netflix.com/en/hardware/
|
||||
[5]: https://i2.wp.com/itsfoss.com/wp-content/uploads/2019/02/netflix-open-connect-appliance.jpeg?fit=800%2C533&ssl=1
|
||||
[6]: https://openconnect.netflix.com/en/software/
|
||||
[7]: https://i0.wp.com/itsfoss.com/wp-content/uploads/2019/02/netflix-freebsd.png?resize=800%2C450&ssl=1
|
||||
[8]: https://www.bsdnow.tv/tutorials/stable-current
|
||||
[9]: https://itsfoss.com/goobuntu-glinux-google/
|
||||
[10]: https://fosdem.org/2019/schedule/event/netflix_freebsd/attachments/slides/3103/export/events/attachments/netflix_freebsd/slides/3103/FOSDEM_2019_Netflix_and_FreeBSD.pdf
|
||||
[11]: http://mirror.onet.pl/pub/mirrors/video.fosdem.org/2019/Janson/netflix_freebsd.webm
|
||||
@@ -1,77 +0,0 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: (geekpi)
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (14 days of celebrating the Raspberry Pi)
|
||||
[#]: via: (https://opensource.com/article/19/3/happy-pi-day)
|
||||
[#]: author: (Anderson Silva (Red Hat) https://opensource.com/users/ansilva)
|
||||
|
||||
庆祝 Raspberry Pi 的 14 天
|
||||
======
|
||||
|
||||
在我们关于树莓派入门系列的第 14 篇也是最后一篇文章中，回顾一下我们学到的所有东西。
|
||||
|
||||
![][1]
|
||||
|
||||
**派节快乐！**
|
||||
|
||||
每年的 3 月 14 日，我们这些极客都会庆祝派节。我们用这种方式缩写日期 MMDD，March 14 于是写成 03/14，它的数字上提醒我们 3.14，或者说 [π][2] 的前三位数字。许多美国人没有意识到的是，世界上几乎没有其他国家使用这种[日期格式][3]，因此派节几乎只适用于美国，尽管它在全球范围内得到了庆祝。
|
||||
|
||||
无论你身在何处，让我们一起庆祝树莓派，并通过回顾过去两周我们所涉及的主题来结束本系列：
|
||||
|
||||
* 第 1 天：[你应该选择哪种树莓派？][4]
|
||||
* 第 2 天：[如何购买树莓派][5]
|
||||
* 第 3 天：[如何启动新的树莓派][6]
|
||||
* 第 4 天：[用树莓派学习 Linux][7]
|
||||
* 第 5 天：[5 种教孩子用树莓派编程的方法][8]
|
||||
* 第 6 天：[你可以用树莓派学习的 3 种流行编程语言][9]
|
||||
* 第 7 天：[如何更新树莓派][10]
|
||||
* 第 8 天：[如何使用树莓派娱乐][11]
|
||||
* 第 9 天：[在树莓派上玩游戏][12]
|
||||
* 第 10 天：[让我们实物化：如何在树莓派上使用 GPIO 引脚][13]
|
||||
* 第 11 天：[通过树莓派了解计算机安全][14]
|
||||
* 第 12 天：[在树莓派上使用 Mathematica 进行高级数学运算][15]
|
||||
* 第 13 天：[为树莓派社区做出贡献][16]
|
||||
|
||||
|
||||
|
||||
![Pi Day illustration][18]
|
||||
|
||||
我将结束本系列，感谢所有关注的人，尤其是那些在过去 14 天里从中学到了东西的人！我还想鼓励大家不断扩展他们对树莓派以及围绕它构建的所有开源（和闭源）技术的了解。
|
||||
|
||||
我还鼓励你了解其他文化、哲学、宗教和世界观。让我们成为人类的是这种惊人的 (有时是有趣的) 能力，我们不仅要适应外部环境，而且要适应智力环境。
|
||||
|
||||
不管你做什么，保持学习！
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/19/3/happy-pi-day
|
||||
|
||||
作者：[Anderson Silva (Red Hat)][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[geekpi](https://github.com/geekpi)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/raspberry-pi-juggle.png?itok=oTgGGSRA
|
||||
[2]: https://www.piday.org/million/
|
||||
[3]: https://en.wikipedia.org/wiki/Date_format_by_country
|
||||
[4]: https://opensource.com/article/19/3/which-raspberry-pi-choose
|
||||
[5]: https://opensource.com/article/19/3/how-buy-raspberry-pi
|
||||
[6]: https://opensource.com/article/19/3/how-boot-new-raspberry-pi
|
||||
[7]: https://opensource.com/article/19/3/learn-linux-raspberry-pi
|
||||
[8]: https://opensource.com/article/19/3/teach-kids-program-raspberry-pi
|
||||
[9]: https://opensource.com/article/19/3/programming-languages-raspberry-pi
|
||||
[10]: https://opensource.com/article/19/3/how-raspberry-pi-update
|
||||
[11]: https://opensource.com/article/19/3/raspberry-pi-entertainment
|
||||
[12]: https://opensource.com/article/19/3/play-games-raspberry-pi
|
||||
[13]: https://opensource.com/article/19/3/gpio-pins-raspberry-pi
|
||||
[14]: https://opensource.com/article/19/3/learn-about-computer-security-raspberry-pi
|
||||
[15]: https://opensource.com/article/19/3/do-math-raspberry-pi
|
||||
[16]: https://opensource.com/article/19/3/contribute-raspberry-pi-community
|
||||
[17]: /file/426561
|
||||
[18]: https://opensource.com/sites/default/files/uploads/raspberrypi_14_piday.jpg (Pi Day illustration)
|
||||
@@ -0,0 +1,189 @@
|
||||
[#]: collector: "lujun9972"
|
||||
[#]: translator: "zero-MK"
|
||||
[#]: reviewer: " "
|
||||
[#]: publisher: " "
|
||||
[#]: url: " "
|
||||
[#]: subject: "How To Check If A Port Is Open On Multiple Remote Linux System Using Shell Script With nc Command?"
|
||||
[#]: via: "https://www.2daygeek.com/check-a-open-port-on-multiple-remote-linux-server-using-nc-command/"
|
||||
[#]: author: "Magesh Maruthamuthu https://www.2daygeek.com/author/magesh/"
|
||||
|
||||
|
||||
|
||||
# 如何使用带有 nc 命令的 Shell 脚本来检查多个远程 Linux 系统是否打开了指定端口？
|
||||
|
||||
我们最近写了一篇文章关于如何检查远程 Linux 服务器是否打开指定端口。它能帮助您检查单个服务器。
|
||||
|
||||
如果要检查五个服务器有没有问题，可以使用以下任何一个命令，如 nc（netcat），nmap 和 telnet。
|
||||
|
||||
但是如果想检查 50 多台服务器，那么你的解决方案是什么？
|
||||
|
||||
要检查所有服务器并不容易，如果你一个一个这样做，完全没有必要，因为这样你将会浪费大量的时间。
|
||||
|
||||
为了解决这种情况，我使用 nc 命令编写了一个 shell 小脚本，它将允许我们扫描任意数量服务器给定的端口。
|
||||
|
||||
如果您要查找单个服务器扫描，您有多个选择，你只需导航到到 **[检查远程 Linux 系统上的端口是否打开？][1]** 了解更多信息。
|
||||
|
||||
本教程中提供了两个脚本，这两个脚本都很有用。
|
||||
|
||||
这两个脚本都用于不同的目的，您可以通过阅读标题轻松理解其用途。
|
||||
|
||||
在你阅读这篇文章之前，我会问你几个问题，如果你知道答案或者你可以通过阅读这篇文章来获得答案。
|
||||
|
||||
如何检查一个远程 Linux 服务器上指定的端口是否打开？
|
||||
|
||||
如何检查多个远程 Linux 服务器上指定的端口是否打开？
|
||||
|
||||
如何检查多个远程 Linux 服务器上是否打开了多个指定的端口？
|
||||
|
||||
### 什么是nc（netcat）命令？
|
||||
|
||||
nc 即 netcat 。Netcat 是一个简单实用的 Unix 程序，它使用 TCP 或 UDP 协议进行跨网络连接进行数据读取和写入。
|
||||
|
||||
它被设计成一个可靠的 “后端” (back-end) 工具，我们可以直接使用或由其他程序和脚本轻松驱动它。
|
||||
|
||||
同时，它也是一个功能丰富的网络调试和探索工具，因为它可以创建您需要的几乎任何类型的连接，并具有几个有趣的内置功能。
|
||||
|
||||
Netcat 有三个主要的模式。分别是连接模式，监听模式和隧道模式。
|
||||
|
||||
**nc（netcat）的通用语法：**
|
||||
|
||||
```
|
||||
$ nc [-options] [HostName or IP] [PortNumber]
|
||||
```
|
||||
|
||||
### 如何检查多个远程 Linux 服务器上的端口是否打开？
|
||||
|
||||
如果要检查多个远程 Linux 服务器上给定端口是否打开，请使用以下 shell 脚本。
|
||||
|
||||
在我的例子中，我们将检查端口 22 是否在以下远程服务器中打开，确保您已经更新文件中的服务器列表而不是还是使用我的服务器列表。
|
||||
|
||||
您必须确保已经更新服务器列表 ： `server-list.txt file` 。每个服务器（IP）应该在单独的行中。
|
||||
|
||||
```
|
||||
# cat server-list.txt
|
||||
192.168.1.2
|
||||
192.168.1.3
|
||||
192.168.1.4
|
||||
192.168.1.5
|
||||
192.168.1.6
|
||||
192.168.1.7
|
||||
```
|
||||
|
||||
使用以下脚本可以达到此目的。
|
||||
|
||||
```
|
||||
# vi port_scan.sh
|
||||
|
||||
#!/bin/sh
|
||||
for server in `more server-list.txt`
|
||||
do
|
||||
#echo $i
|
||||
nc -zvw3 $server 22
|
||||
done
|
||||
```
|
||||
|
||||
设置 `port_scan.sh` 文件的可执行权限。
|
||||
|
||||
```
|
||||
$ chmod +x port_scan.sh
|
||||
```
|
||||
|
||||
最后运行脚本来达到此目的。
|
||||
|
||||
```
|
||||
# sh port_scan.sh
|
||||
|
||||
Connection to 192.168.1.2 22 port [tcp/ssh] succeeded!
|
||||
Connection to 192.168.1.3 22 port [tcp/ssh] succeeded!
|
||||
Connection to 192.168.1.4 22 port [tcp/ssh] succeeded!
|
||||
Connection to 192.168.1.5 22 port [tcp/ssh] succeeded!
|
||||
Connection to 192.168.1.6 22 port [tcp/ssh] succeeded!
|
||||
Connection to 192.168.1.7 22 port [tcp/ssh] succeeded!
|
||||
```
|
||||
|
||||
### 如何检查多个远程 Linux 服务器上是否打开多个端口？
|
||||
|
||||
如果要检查多个服务器中的多个端口，请使用下面的脚本。
|
||||
|
||||
在我的例子中，我们将检查给定服务器的 22 和 80 端口是否打开。确保您必须替换所需的端口和服务器名称而不使用是我的。
|
||||
|
||||
您必须确保已经将要检查的端口写入 `port-list.txt` 文件中。每个端口应该在一个单独的行中。
|
||||
|
||||
```
|
||||
# cat port-list.txt
|
||||
22
|
||||
80
|
||||
```
|
||||
|
||||
您必须确保已经将要检查的服务器（ IP 地址 ）写入 `server-list.txt` 到文件中。每个服务器（ IP ） 应该在单独的行中。
|
||||
|
||||
```
|
||||
# cat server-list.txt
|
||||
192.168.1.2
|
||||
192.168.1.3
|
||||
192.168.1.4
|
||||
192.168.1.5
|
||||
192.168.1.6
|
||||
192.168.1.7
|
||||
```
|
||||
|
||||
使用以下脚本来达成此目的。
|
||||
|
||||
```
|
||||
# vi multiple_port_scan.sh
|
||||
|
||||
#!/bin/sh
|
||||
for server in `more server-list.txt`
|
||||
do
|
||||
for port in `more port-list.txt`
|
||||
do
|
||||
#echo $server
|
||||
nc -zvw3 $server $port
|
||||
echo ""
|
||||
done
|
||||
done
|
||||
```
|
||||
|
||||
设置 `multiple_port_scan.sh` 文件的可执行权限。
|
||||
|
||||
```
|
||||
$ chmod +x multiple_port_scan.sh
|
||||
```
|
||||
|
||||
最后运行脚本来实现这一目的。
|
||||
|
||||
```
|
||||
# sh multiple_port_scan.sh
|
||||
Connection to 192.168.1.2 22 port [tcp/ssh] succeeded!
|
||||
Connection to 192.168.1.2 80 port [tcp/http] succeeded!
|
||||
|
||||
Connection to 192.168.1.3 22 port [tcp/ssh] succeeded!
|
||||
Connection to 192.168.1.3 80 port [tcp/http] succeeded!
|
||||
|
||||
Connection to 192.168.1.4 22 port [tcp/ssh] succeeded!
|
||||
Connection to 192.168.1.4 80 port [tcp/http] succeeded!
|
||||
|
||||
Connection to 192.168.1.5 22 port [tcp/ssh] succeeded!
|
||||
Connection to 192.168.1.5 80 port [tcp/http] succeeded!
|
||||
|
||||
Connection to 192.168.1.6 22 port [tcp/ssh] succeeded!
|
||||
Connection to 192.168.1.6 80 port [tcp/http] succeeded!
|
||||
|
||||
Connection to 192.168.1.7 22 port [tcp/ssh] succeeded!
|
||||
Connection to 192.168.1.7 80 port [tcp/http] succeeded!
|
||||
```
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.2daygeek.com/check-a-open-port-on-multiple-remote-linux-server-using-nc-command/
|
||||
|
||||
作者：[Magesh Maruthamuthu][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[zero-MK](https://github.com/zero-mk)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://www.2daygeek.com/author/magesh/
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://www.2daygeek.com/how-to-check-whether-a-port-is-open-on-the-remote-linux-system-server/
|
||||
221
translated/tech/20190325 Getting started with Vim- The basics.md
Normal file
221
translated/tech/20190325 Getting started with Vim- The basics.md
Normal file
@@ -0,0 +1,221 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: (Modrisco)
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (Getting started with Vim: The basics)
|
||||
[#]: via: (https://opensource.com/article/19/3/getting-started-vim)
|
||||
[#]: author: (Bryant Son (Red Hat, Community Moderator) https://opensource.com/users/brson)
|
||||
|
||||
Vim 入门：基础
|
||||
======
|
||||
|
||||
为工作或者新项目学习足够的 Vim 知识。
|
||||
|
||||
![Person standing in front of a giant computer screen with numbers, data][1]
|
||||
|
||||
我还清晰地记得我第一次接触 Vim 的时候。那时我还是一名大学生，计算机学院的机房里都装着 Ubuntu 系统。尽管我在上大学前也曾接触过不同的 Linux 发行版（比如 RHEL，Red Hat 在百思买出售它的 CD），但这却是我第一次要在日常中频繁使用 Linux 系统，因为我的课程要求我这样做。当我开始使用 Linux 时，正如我的前辈和将来的后继者们一样，我感觉自己像是一名“真正的程序员”了。
|
||||
|
||||
![Real Programmers comic][2]
|
||||
|
||||
真正的程序员，来自 [xkcd][3]
|
||||
|
||||
学生们可以使用像 [Kate][4] 一样的图形文本编辑器，这也安装在学校的电脑上了。对于那些可以使用 shell 但不习惯使用控制台编辑器的学生，最流行的选择是 [Nano][5]，它提供了很好的交互式菜单和类似于 Windows 图形文本编辑器的体验。
|
||||
|
||||
我有时会用 Nano，但当我听说 [Vi/Vim][6] 和 [Emacs][7] 能做一些很棒的事情时我决定试一试它们（主要是因为它们看起来很酷，而且我也很好奇它们有什么特别之处）。第一次使用 Vim 时吓到我了 —— 我不想搞砸任何事情！但是，一旦我掌握了它的诀窍，事情就变得容易得多，我可以欣赏编辑器的强大功能。至于 Emacs，呃，我有点放弃了，但我很高兴我坚持和 Vim 在一起。
|
||||
|
||||
在本文中，我将介绍一下 Vim（基于我的个人经验），这样你就可以在 Linux 系统上用它来作为编辑器使用了。这篇文章不会让你变成 Vim 的专家，甚至不会触及 Vim 许多强大功能的皮毛。但是起点总是很重要的，我想让开始的经历尽可能简单，剩下的则由你自己去探索。
|
||||
|
||||
### 第 0 步：打开一个控制台窗口
|
||||
|
||||
在使用 Vim 前，你需要做一些准备工作。在 Linux 操作系统打开控制台终端。（因为 Vim 也可以在 MacOS 上使用，Mac 用户也可以使用这些说明）。
|
||||
|
||||
打开终端窗口后，输入 `ls` 命令列出当前目录下的内容。然后，输入 `mkdir Tutorial` 命令创建一个名为 `Tutorial` 的新目录。通过输入 `cd Tutorial` 来进入该目录。
|
||||
|
||||
![Create a folder][8]
|
||||
|
||||
这就是全部的准备工作。现在是时候转到有趣的部分了——开始使用 Vim。
|
||||
|
||||
### 第 1 步：创建一个 Vim 文件和不保存退出
|
||||
|
||||
还记得我一开始说过我不敢使用 Vim 吗？我当时在害怕“如果我改变了一个现有的文件，把事情搞砸了怎么办？”毕竟，一些计算机科学作业要求我修改现有的文件。我想知道：_如何在不保存更改的情况下打开和关闭文件？_
|
||||
|
||||
好消息是你可以使用相同的命令在 Vim 中创建或打开文件：`vim <FILE_NAME>`，其中 **<FILE_NAME>** 表示要创建或修改的目标文件名。让我们通过输入 `vim HelloWorld.java` 来创建一个名为 `HelloWorld.java` 的文件。
|
||||
|
||||
你好，Vim！现在，讲一下 Vim 中一个非常重要的概念，可能也是最需要记住的：Vim 有多种模式，下面是 Vim 基础中需要知道的的三种：
|
||||
|
||||
模式 | 描述
|
||||
---|---
|
||||
正常模式 | 默认模式，用于导航和简单编辑
|
||||
插入模式 | 用于插入和修改文本
|
||||
命令模式 | 用于执行如保存，退出等命令
|
||||
|
||||
Vim 也有其他模式，例如可视模式、选择模式和命令模式。不过上面的三种模式对我们来说已经足够好了。
|
||||
|
||||
你现在正处于正常模式，如果有文本，你可以用箭头键移动或使用其他导航键（将在稍后看到）。要确定你正处于正常模式，只需按下 `esc` (Escape）键即可。
|
||||
|
||||
> **提示:** **Esc** 切换到正常模式。即使你已经在正常模式下，点击 **Esc** 只是为了练习。
|
||||
|
||||
现在，有趣的事情发生了。输入 `:` （冒号键）并接着 `q!` (完整命令：`:q!`)。你的屏幕将显示如下：
|
||||
|
||||
![Editing Vim][9]
|
||||
|
||||
在正常模式下输入冒号会将 Vim 切换到命令行模式，执行 `:q!` 命令将退出 Vim 编辑器而不进行保存。换句话说，你放弃了所有的更改。你也可以使用 `ZQ` 命令；选择你认为更方便的选项。
|
||||
|
||||
一旦你按下 `Enter` （回车），你就不再在 Vim 中。重复练习几次来掌握这条命令。熟悉了这部分内容之后，请转到下一节，了解如何对文件进行更改。
|
||||
|
||||
### 第 2 步：在 Vim 中修改并保存
|
||||
|
||||
通过输入 `vim HelloWorld.java` 和回车键来再次打开这个文件。你可以在插入模式中修改文件。首先，通过 `Esc` 键来确定你正处于正常模式。接着输入 `i` 来进入插入模式（没错，就是字母 **i**）。
|
||||
|
||||
在左下角，你将看到 `\-- INSERT --`，这标志着你这处于插入模式。
|
||||
|
||||
![Vim insert mode][10]
|
||||
|
||||
写一些 Java 代码。你可以写任何你想写的，不过这也有一份你可以参照的例子。你的屏幕将显示如下：
|
||||
|
||||
```
|
||||
public class HelloWorld {
|
||||
public static void main([String][11][] args) {
|
||||
}
|
||||
}
|
||||
```
|
||||
非常漂亮！注意文本是如何在 Java 语法中高亮显示的。因为这是个 Java 文件，所以 Vim 将自动检测语法并高亮颜色。
|
||||
|
||||
保存文件：按下 `Esc` 来退出插入模式并进入命令模式。输入 `:` 并接着 `x!` (完整命令：`:x!`)，按回车键来保存文件。你也可以输入 `wq` 来执行相同的操作。
|
||||
|
||||
现在，你知道了如何使用插入模式输入文本并使用以下命令保存文件：`:x!` 或者 `:wq`。
|
||||
|
||||
### 第 3 步：Vim 中的基本导航
|
||||
|
||||
虽然你总是可以使用上箭头、下箭头、左箭头和右箭头在文件中移动，但在一个几乎有数不清行数的大文件中，这将是非常困难的。能够在一行中跳跃光标将会是很有用的。虽然 Vim 提供了不少很棒的导航功能，不过在一开始，我想向你展示如何在 Vim 中到达某一特定的行。
|
||||
|
||||
单击 `Esc` 来确定你处于正常模式，接着输入 `:set number` 并键入回车。
|
||||
|
||||
瞧！你现在可以在每一行的左侧看到行号。
|
||||
|
||||
![Showing Line Numbers][12]
|
||||
|
||||
好，你也许会说，“这确实很酷，不过我该怎么跳到某一行呢？”再一次的，确认你正处于正常模式。接着输入 `: <LINE_NUMBER>`，在这里 **< LINE_NUMBER>** 是你想去的那一行的行数。按下回车键来试着移动到第二行。
|
||||
|
||||
```
|
||||
:2
|
||||
```
|
||||
|
||||
现在，跳到第三行。
|
||||
|
||||
![Jump to line 3][13]
|
||||
|
||||
但是，假如你正在处理一个一千多行的文件，而你正想到文件底部。这该怎么办呢？确认你正处于正常模式，接着输入 `:$` 并按下回车。
|
||||
|
||||
你将来到最后一行！
|
||||
|
||||
现在，你知道如何在行间跳跃了，作为补充，我们来学一下如何移动到一行的行尾。确认你正处于有文本内容的一行，如第三行，接着输入 `$`。
|
||||
|
||||
![Go to the last character][14]
|
||||
|
||||
你现在来到这行的最后一个字节了。在此示例中，高亮左大括号以显示光标移动到的位置，右大括号被高亮是因为它是高亮的左大括号的匹配字符。
|
||||
|
||||
这就是 Vim 中的基本导航功能。等等，别急着退出文件。让我们转到 Vim 中的基本编辑。不过，你可以暂时随便喝杯咖啡或茶休息一下。
|
||||
|
||||
### 第 4 步：Vim 中的基本编辑
|
||||
|
||||
现在，你已经知道如何通过跳到想要的一行来在文件中导航，你可以使用这个技能在 Vim 中进行一些基本编辑。切换到插入模式。（还记得怎么做吗？是不是输入 `i` ？）当然，你可以使用键盘逐一删除或插入字符来进行编辑，但是 Vim 提供了更快捷的方法来编辑文件。
|
||||
|
||||
来到第三行，这里的代码是 **public static void main(String[] args) {**。双击 `d` 键，没错，就是 `dd`。如果你成功做到了，你将会看到，第三行消失了，剩下的所有行都向上移动了一行。（例如，第四行变成了第三行）。
|
||||
|
||||
![Deleting A Line][15]
|
||||
|
||||
这就是 _删除_（delete） 命令。不要担心，键入 `u`，你会发现这一行又回来了。喔，这就是 _撤销_（undo） 命令。
|
||||
|
||||
![Undoing a change in Vim][16]
|
||||
|
||||
下一课是学习如何复制和粘贴文本，但首先，你需要学习如何在 Vim 中突出显示文本。按下 `v` 并向左右移动光标来选择或反选文本。当你向其他人展示代码并希望标识你想让他们注意到的代码时，这个功能也非常有用。
|
||||
|
||||
![Highlighting text in Vim][17]
|
||||
|
||||
来到第四行，这里的代码是 **System.out.println("Hello, Opensource");**。高亮这一行的所有内容。好了吗？当第四行的内容处于高亮时，按下 `y`。这就叫做 _复制_（yank）模式，文本将会被复制到剪贴板上。接下来，输入 `o` 来创建新的一行。注意，这将让你进入插入模式。通过按 `Esc` 退出插入模式，然后按下 `p`，代表 _粘贴_。这将把复制的文本从第三行粘贴到第四行。
|
||||
|
||||
![Pasting in Vim][18]
|
||||
|
||||
作为练习，请重复这些步骤，但也要修改新创建的行中的文字。此外，请确保这些行对齐工整。
|
||||
|
||||
> **提示：** 您需要在插入模式和命令行模式之间来回切换才能完成此任务。
|
||||
|
||||
当你完成了，通过 `x!` 命令保存文件。以上就是 Vim 基本编辑的全部内容。
|
||||
|
||||
### 第 5 步：Vim 中的基本搜索
|
||||
|
||||
假设你的团队领导希望你更改项目中的文本字符串。你该如何快速完成任务？你可能希望使用某个关键字来搜索该行。
|
||||
|
||||
Vim 的搜索功能非常有用。通过 `Esc` 键来进入命令模式，然后输入冒号 `:`，我们可以通过输入 `/ <SEARCH_KEYWORD>` 来搜索关键词， **< SEARCH_KEYWORD>** 指你希望搜索的字符串。在这里，我们搜索关键字符串 “Hello”。在面的图示中缺少冒号，但这是必需的。
|
||||
|
||||
![Searching in Vim][19]
|
||||
|
||||
但是，一个关键字可以出现不止一次，而这可能不是你想要的那一个。那么，如何找到下一个匹配项呢？只需按 `n` 键即可，这代表 _下一个_（next）。执行此操作时，请确保你没有处于插入模式！
|
||||
|
||||
### 附加步骤：Vim中的分割模式
|
||||
|
||||
以上几乎涵盖了所有的 Vim 基础知识。但是，作为一个额外奖励，我想给你展示 Vim 一个很酷的特性，叫做 _分割_（split）模式。
|
||||
|
||||
退出 _HelloWorld.java_ 并创建一个新文件。在控制台窗口中，输入 `vim GoodBye.java` 并按回车键来创建一个名为 _GoodBye.java_ 的新文件。
|
||||
|
||||
输入任何你想输入的让内容，我选择输入“Goodbye”。保存文件（记住你可以在命令模式中使用 `:x!` 或者 `:wq`）。
|
||||
|
||||
在命令模式中，输入 `:split HelloWorld.java`，来看看发生了什么。
|
||||
|
||||
![Split mode in Vim][20]
|
||||
|
||||
Wow！快看！**split** 命令将控制台窗口水平分割成了两个部分，上面是 _HelloWorld.java_，下面是 _GoodBye.java_。该怎么能在窗口之间切换呢？按住 `Control` 键 (在 Mac 上)或 `Ctrl` 键（在PC上），然后按下 `ww` (即双击 `w` 键)。
|
||||
|
||||
作为最后一个练习，尝试通过复制和粘贴 _HelloWorld.java_ 来编辑 _GoodBye.java_ 以匹配下面屏幕上的内容。
|
||||
|
||||
![Modify GoodBye.java file in Split Mode][21]
|
||||
|
||||
保存两份文件，成功！
|
||||
|
||||
> **提示 1:** 如果你想将两个文件窗口垂直分割，使用 `:vsplit <FILE_NAME>` 命令。（代替 `:split <FILE_NAME>` 命令，**< FILE_NAME>** 指你想要使用分割模式打开的文件名）。
|
||||
>
|
||||
> **提示 2:** 你可以通过调用任意数量的 **split** 或者 **vsplit** 命令来打开两个以上的文件。试一试，看看它效果如何。
|
||||
|
||||
### Vim 速查表
|
||||
|
||||
在本文中，您学会了如何使用 Vim 来完成工作或项目。但这只是你开启 Vim 强大功能之旅的开始。请务必在 Opensource.com 上查看其他很棒的教程和技巧。
|
||||
|
||||
为了让一切变得简单些，我已经将你学到的一切总结到了 [a handy cheat sheet][22] 中。
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/19/3/getting-started-vim
|
||||
|
||||
作者：[Bryant Son (Red Hat, Community Moderator)][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[Modrisco](https://github.com/Modrisco)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://opensource.com/users/brson
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/data_metrics_analytics_desktop_laptop.png?itok=9QXd7AUr (Person standing in front of a giant computer screen with numbers, data)
|
||||
[2]: https://opensource.com/sites/default/files/uploads/1_xkcdcartoon.jpg (Real Programmers comic)
|
||||
[3]: https://xkcd.com/378/
|
||||
[4]: https://kate-editor.org
|
||||
[5]: https://www.nano-editor.org
|
||||
[6]: https://www.vim.org
|
||||
[7]: https://www.gnu.org/software/emacs
|
||||
[8]: https://opensource.com/sites/default/files/uploads/2_createtestfolder.jpg (Create a folder)
|
||||
[9]: https://opensource.com/sites/default/files/uploads/4_existingvim.jpg (Editing Vim)
|
||||
[10]: https://opensource.com/sites/default/files/uploads/6_insertionmode.jpg (Vim insert mode)
|
||||
[11]: http://www.google.com/search?hl=en&q=allinurl%3Adocs.oracle.com+javase+docs+api+string
|
||||
[12]: https://opensource.com/sites/default/files/uploads/10_setnumberresult_0.jpg (Showing Line Numbers)
|
||||
[13]: https://opensource.com/sites/default/files/uploads/12_jumpintoline3.jpg (Jump to line 3)
|
||||
[14]: https://opensource.com/sites/default/files/uploads/14_gotolastcharacter.jpg (Go to the last character)
|
||||
[15]: https://opensource.com/sites/default/files/uploads/15_deletinglines.jpg (Deleting A Line)
|
||||
[16]: https://opensource.com/sites/default/files/uploads/16_undoingtheline.jpg (Undoing a change in Vim)
|
||||
[17]: https://opensource.com/sites/default/files/uploads/17_highlighting.jpg (Highlighting text in Vim)
|
||||
[18]: https://opensource.com/sites/default/files/uploads/19_pasting.jpg (Pasting in Vim)
|
||||
[19]: https://opensource.com/sites/default/files/uploads/22_searchmode.jpg (Searching in Vim)
|
||||
[20]: https://opensource.com/sites/default/files/uploads/26_copytonewfiles.jpg (Split mode in Vim)
|
||||
[21]: https://opensource.com/sites/default/files/uploads/27_exercise.jpg (Modify GoodBye.java file in Split Mode)
|
||||
[22]: https://opensource.com/downloads/cheat-sheet-vim
|
||||
102
translated/tech/20190328 How to run PostgreSQL on Kubernetes.md
Normal file
102
translated/tech/20190328 How to run PostgreSQL on Kubernetes.md
Normal file
@@ -0,0 +1,102 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: (arrowfeng)
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (How to run PostgreSQL on Kubernetes)
|
||||
[#]: via: (https://opensource.com/article/19/3/how-run-postgresql-kubernetes)
|
||||
[#]: author: (Jonathan S. Katz https://opensource.com/users/jkatz05)
|
||||
|
||||
怎样在Kubernetes上运行PostgreSQL
|
||||
======
|
||||
创建统一管理的，具备灵活性的云原生生产部署来部署一个人性化的数据库即服务。
|
||||
![cubes coming together to create a larger cube][1]
|
||||
|
||||
通过在[Kubernetes][2]上运行[PostgreSQL][3]数据库，你能创建统一管理的，具备灵活性的云原生生产部署应用来部署一个个性化的数据库即服务为你的特定需求进行量身定制。
|
||||
|
||||
对于Kubernetes，使用Operator允许你提供额外的上下文去[管理有状态应用][4]。当使用像PostgreSQL这样开源的数据库去执行包括配置，扩张，高可用和用户管理时，Operator也很有帮助。
|
||||
|
||||
让我们来探索如何在Kubernetes上启动并运行PostgreSQL。
|
||||
|
||||
### 安装 PostgreSQL Operator
|
||||
|
||||
将PostgreSQL和Kubernetes结合使用的第一步是安装一个Operator。在针对Linux系统的Crunchy's [快速启动脚本][6]的帮助下，你可以在任意基于Kubernetes的环境下启动和运行开源的[Crunchy PostgreSQL Operator][5]。
|
||||
|
||||
快速启动脚本有一些必要前提：
|
||||
|
||||
* [Wget][7]工具已安装。
|
||||
* [kubectl][8]工具已安装。
|
||||
* 一个[StorageClass][9]已经定义在你的Kubernetes中。
|
||||
* 拥有集群权限的可访问Kubernetes的用户账号。安装Operator的[RBAC][10]规则是必要的。
|
||||
* 拥有一个[namespace][11]去管理PostgreSQL Operator。
|
||||
|
||||
|
||||
|
||||
执行这个脚本将提供给你一个默认的PostgreSQL Operator deployment，它假设你的[dynamic storage][12]和存储类的名字为**standard**。通过这个脚本允许用户自定义的值去覆盖这些默认值。
|
||||
|
||||
通过下列命令，你能下载这个快速启动脚本并把它的权限设置为可执行：
|
||||
```
|
||||
wget <https://raw.githubusercontent.com/CrunchyData/postgres-operator/master/examples/quickstart.sh>
|
||||
chmod +x ./quickstart.sh
|
||||
```
|
||||
|
||||
然后你运行快速启动脚本：
|
||||
```
|
||||
./examples/quickstart.sh
|
||||
```
|
||||
|
||||
在脚本提示你相关的Kubernetes集群基本信息后，它将执行下列操作：
|
||||
* 下载Operator配置文件
|
||||
* 将 **$HOME/.pgouser** 这个文件设置为默认设置
|
||||
* 以Kubernetes [Deployment][13]部署Operator
|
||||
* 设置你的 **.bashrc** 文件包含Operator环境变量
|
||||
* 设置你的 **$HOME/.bash_completion** 文件为 **pgo bash_completion**文件
|
||||
|
||||
在快速启动脚本的执行期间，你将会被提示在你的Kubernetes集群设置RBAC规则。在另一个终端，执行快速启动命令所提示你的命令。
|
||||
|
||||
一旦这个脚本执行完成，你将会得到关于打开一个端口转发到PostgreSQL Operator pod的信息。在另一个终端，执行端口转发；这将允许你开始对PostgreSQL Operator执行命令！尝试输入下列命令创建集群：
|
||||
|
||||
```
|
||||
pgo create cluster mynewcluster
|
||||
```
|
||||
|
||||
你能输入下列命令测试你的集群运行状况：
|
||||
|
||||
```
|
||||
pgo test mynewcluster
|
||||
```
|
||||
|
||||
现在，你能在Kubernetes环境下管理你的PostgreSQL数据库！你可以在[官方文档][14]找到非常全面的命令，包括扩容，高可用，备份等等。
|
||||
|
||||
* * *
|
||||
这篇文章部分参考了该作者为了Crunchy博客而写的[在Kubernetes上开始运行PostgreSQL][15]
|
||||
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/19/3/how-run-postgresql-kubernetes
|
||||
|
||||
作者：[Jonathan S. Katz][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[arrowfeng](https://github.com/arrowfeng)
|
||||
校对：[校对ID](https://github.com/校对ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://opensource.com/users/jkatz05
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/cube_innovation_process_block_container.png?itok=vkPYmSRQ (cubes coming together to create a larger cube)
|
||||
[2]: https://www.postgresql.org/
|
||||
[3]: https://kubernetes.io/
|
||||
[4]: https://opensource.com/article/19/2/scaling-postgresql-kubernetes-operators
|
||||
[5]: https://github.com/CrunchyData/postgres-operator
|
||||
[6]: https://crunchydata.github.io/postgres-operator/stable/installation/#quickstart-script
|
||||
[7]: https://www.gnu.org/software/wget/
|
||||
[8]: https://kubernetes.io/docs/tasks/tools/install-kubectl/
|
||||
[9]: https://kubernetes.io/docs/concepts/storage/storage-classes/
|
||||
[10]: https://kubernetes.io/docs/reference/access-authn-authz/rbac/
|
||||
[11]: https://kubernetes.io/docs/concepts/overview/working-with-objects/namespaces/
|
||||
[12]: https://kubernetes.io/docs/concepts/storage/dynamic-provisioning/
|
||||
[13]: https://kubernetes.io/docs/concepts/workloads/controllers/deployment/
|
||||
[14]: https://crunchydata.github.io/postgres-operator/stable/#documentation
|
||||
[15]: https://info.crunchydata.com/blog/get-started-runnning-postgresql-on-kubernetes
|
||||
@@ -0,0 +1,158 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: (HankChow)
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (Using Square Brackets in Bash: Part 2)
|
||||
[#]: via: (https://www.linux.com/blog/learn/2019/4/using-square-brackets-bash-part-2)
|
||||
[#]: author: (Paul Brown https://www.linux.com/users/bro66)
|
||||
|
||||
在 Bash 中使用[方括号]（二）
|
||||
======
|
||||
|
||||
![square brackets][1]
|
||||
|
||||
> 我们继续来看方括号的用法，它们甚至还可以在 Bash 当中作为一个命令使用。
|
||||
|
||||
[Creative Commons Zero][2]
|
||||
|
||||
欢迎回到我们的方括号专题。在[前一篇文章][3]当中，我们介绍了方括号在命令行中可以用于通配操作，如果你已经读过前一篇文章，就可以从这里继续了。
|
||||
|
||||
方括号还可以以一个命令的形式使用，就像这样：
|
||||
|
||||
```
|
||||
[ "a" = "a" ]
|
||||
```
|
||||
|
||||
上面这种 `[ ... ]` 的形式就可以看成是一个可执行的命令。要注意，方括号内部的内容 `"a" = "a"` 和方括号 `[`、`]` 之间是有空格隔开的。因为这里的方括号被视作一个命令，因此要用空格将命令和它的参数隔开。
|
||||
|
||||
上面这个命令的含义是“判断字符串 `"a"` 和字符串 `"a"` 是否相同”，如果判断结果为真，那么 `[ ... ]` 就会以<ruby>状态码<rt>status code</rt></ruby> 0 退出，否则以状态码 1 退出。在之前的文章中，我们也有介绍过状态码的概念，可以通过 `$?` 变量获取到最近一个命令的状态码。
|
||||
|
||||
分别执行
|
||||
|
||||
```
|
||||
[ "a" = "a" ]
|
||||
echo $?
|
||||
```
|
||||
|
||||
以及
|
||||
|
||||
```
|
||||
[ "a" = "b" ]
|
||||
echo $?
|
||||
```
|
||||
|
||||
这两段命令中，前者会输出 0（判断结果为真），后者则会输出 1（判断结果为假）。在 Bash 当中，如果一个命令的状态码是 0，表示这个命令正常执行完成并退出，而且其中没有出现错误，对应布尔值 `true`；如果在命令执行过程中出现错误，就会返回一个非零的状态码，对应布尔值 `false`。而 `[ ... ]`也同样遵循这样的规则。
|
||||
|
||||
因此，`[ ... ]` 很适合在 `if ... then`、`while` 或 `until` 这种在代码块结束前需要判断是否达到某个条件结构中使用。
|
||||
|
||||
对应使用的逻辑判断运算符也相当直观：
|
||||
|
||||
```
|
||||
[ STRING1 = STRING2 ] => checks to see if the strings are equal
|
||||
[ STRING1 != STRING2 ] => checks to see if the strings are not equal
|
||||
[ INTEGER1 -eq INTEGER2 ] => checks to see if INTEGER1 is equal to INTEGER2
|
||||
[ INTEGER1 -ge INTEGER2 ] => checks to see if INTEGER1 is greater than or equal to INTEGER2
|
||||
[ INTEGER1 -gt INTEGER2 ] => checks to see if INTEGER1 is greater than INTEGER2
|
||||
[ INTEGER1 -le INTEGER2 ] => checks to see if INTEGER1 is less than or equal to INTEGER2
|
||||
[ INTEGER1 -lt INTEGER2 ] => checks to see if INTEGER1 is less than INTEGER2
|
||||
[ INTEGER1 -ne INTEGER2 ] => checks to see if INTEGER1 is not equal to INTEGER2
|
||||
etc...
|
||||
```
|
||||
|
||||
方括号的这种用法也可以很有 shell 风格，例如通过带上 `-f` 参数可以判断某个文件是否存在：
|
||||
|
||||
```
|
||||
for i in {000..099}; \
|
||||
do \
|
||||
if [ -f file$i ]; \
|
||||
then \
|
||||
echo file$i exists; \
|
||||
else \
|
||||
touch file$i; \
|
||||
echo I made file$i; \
|
||||
fi; \
|
||||
done
|
||||
```
|
||||
|
||||
如果你在上一篇文章使用到的测试目录中运行以上这串命令，其中的第 3 行会判断那几十个文件当中的某个文件是否存在。如果文件存在，会输出一条提示信息；如果文件不存在，就会把对应的文件创建出来。最终，这个目录中会完整存在从 `file000` 到 `file099` 这一百个文件。
|
||||
|
||||
上面这段命令还可以写得更加简洁：
|
||||
|
||||
```
|
||||
for i in {000..099};\
|
||||
do\
|
||||
if [ ! -f file$i ];\
|
||||
then\
|
||||
touch file$i;\
|
||||
echo I made file$i;\
|
||||
fi;\
|
||||
done
|
||||
```
|
||||
|
||||
其中 `!` 运算符表示将判断结果取反，因此第 3 行的含义就是“如果文件 `file$i` 不存在”。
|
||||
|
||||
可以尝试一下将测试目录中那几十个文件随意删除几个，然后运行上面的命令，你就可以看到它是如何把被删除的文件重新创建出来的。
|
||||
|
||||
除了 `-f` 之外，还有很多有用的参数。`-d` 参数可以判断某个目录是否存在，`-h` 参数可以判断某个文件是不是一个符号链接。可以用 `-G` 参数判断某个文件是否属于某个用户组，用 `-ot` 参数判断某个文件的最后更新时间是否早于另一个文件，甚至还可以判断某个文件是否为空文件。
|
||||
|
||||
运行下面的几条命令，可以向几个文件中写入一些内容：
|
||||
|
||||
```
|
||||
echo "Hello World" >> file023
|
||||
echo "This is a message" >> file065
|
||||
echo "To humanity" >> file010
|
||||
```
|
||||
|
||||
然后运行：
|
||||
|
||||
```
|
||||
for i in {000..099};\
|
||||
do\
|
||||
if [ ! -s file$i ];\
|
||||
then\
|
||||
rm file$i;\
|
||||
echo I removed file$i;\
|
||||
fi;\
|
||||
done
|
||||
```
|
||||
|
||||
你就会发现所有空文件都被删除了，只剩下少数几个非空的文件。
|
||||
|
||||
如果你还想了解更多别的参数，可以执行 `man test` 来查看 `test` 命令的 man 手册（`test` 是 `[ ... ]` 的命令别名）。
|
||||
|
||||
有时候你还会看到 `[[ ... ]]` 这种双方括号的形式，使用起来和单方括号差别不大。但双方括号支持的比较运算符更加丰富：例如可以使用 `==` 来判断某个字符串是否符合某个<ruby>模式<rt>pattern</rt></ruby>，也可以使用 `<`、`>` 来判断两个字符串的出现顺序。
|
||||
|
||||
可以在 [Bash 表达式文档][5]中了解到双方括号支持的更多运算符。
|
||||
|
||||
### 下一集
|
||||
|
||||
在下一篇文章中，我们会开始介绍圆括号 `()` 在 Linux 命令行中的用法，敬请关注！
|
||||
|
||||
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.linux.com/blog/learn/2019/4/using-square-brackets-bash-part-2
|
||||
|
||||
作者：[Paul Brown][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[HankChow](https://github.com/HankChow)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://www.linux.com/users/bro66
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://www.linux.com/sites/lcom/files/styles/rendered_file/public/square-brackets-3734552_1920.jpg?itok=hv9D6TBy "square brackets"
|
||||
[2]: /LICENSES/CATEGORY/CREATIVE-COMMONS-ZERO
|
||||
[3]: https://www.linux.com/blog/2019/3/using-square-brackets-bash-part-1
|
||||
[4]: https://www.linux.com/blog/learn/2019/2/logical-ampersand-bash
|
||||
[5]: https://www.gnu.org/software/bash/manual/bashref.html#Bash-Conditional-Expressions
|
||||
[6]: https://www.linux.com/blog/learn/2019/1/linux-tools-meaning-dot
|
||||
[7]: https://www.linux.com/blog/learn/2019/1/understanding-angle-brackets-bash
|
||||
[8]: https://www.linux.com/blog/learn/2019/1/more-about-angle-brackets-bash
|
||||
[9]: https://www.linux.com/blog/learn/2019/2/and-ampersand-and-linux
|
||||
[10]: https://www.linux.com/blog/learn/2019/2/ampersands-and-file-descriptors-bash
|
||||
[11]: https://www.linux.com/blog/learn/2019/2/all-about-curly-braces-bash
|
||||
|
||||
64
translated/tech/20190409 Enhanced security at the edge.md
Normal file
64
translated/tech/20190409 Enhanced security at the edge.md
Normal file
@@ -0,0 +1,64 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: (hopefully2333)
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (Enhanced security at the edge)
|
||||
[#]: via: (https://www.networkworld.com/article/3388130/enhanced-security-at-the-edge.html#tk.rss_all)
|
||||
[#]: author: (Anne Taylor https://www.networkworld.com/author/Anne-Taylor/)
|
||||
|
||||
增强边缘计算的安全性
|
||||
======
|
||||
边缘计算环境带来的安全风险迫使公司必须特别关注它的安全措施。
|
||||
|
||||
说数据安全是高管们和董事会最关注的问题已经是陈词滥调了。但问题是：数据安全问题不会自己消失。
|
||||
|
||||
骇客和攻击者一直在寻找利用漏洞的新方法。就像公司开始使用人工智能和机器学习等新兴技术来自动化地保护他们的组织一样，攻击者们也在使用这些技术来达成他们的目的。
|
||||
|
||||
简而言之，安全问题是一定不能忽视的。现在，随着越来越多的公司开始使用边缘计算，如何保护这些边缘计算环境，需要有新的安全考量。
|
||||
|
||||
**边缘计算的风险更高**
|
||||
|
||||
正如 Network World 中一篇文章所建议的，边缘计算的安全架构应该将重点放在物理安全上。这并不是说要忽视，保护传输过程中的数据这一点。而是说，实际情况里的物理环境和物理设备更加值得关注。
|
||||
|
||||
例如，边缘计算的硬件设备通常位于大公司或者广阔空间中，有时候是在很容易进入的共享办公室和公共区域里。从表面上看，这节省了成本，能更快地访问到相关的数据，而不必在后端的数据中心和前端的设备之间往返。
|
||||
|
||||
但是，如果没有任何级别的访问控制，这台设备就会暴露在恶意操作和简单人为错误的双重风险之下。想象一下办公室的清洁工意外地关掉了设备，以及随之而来的设置停机所造成的后果。
|
||||
|
||||
另一个风险是 “Shadow edge IT”。有时候非 IT 的工作人员会部署一个边缘站点来实现快速启动项目，却没有及时通知 IT 部门这个站点正在连接到网络。例如，零售商店可能会主动安装他们自己的数字标牌，或者，销售团队会将物联网传感器应用到电视中，并在销售演示中实时地部署它们。
|
||||
|
||||
在这种情况下，IT 部门很少甚至完全看不到这些设备和边缘站点，这就使得网络可能暴露在外。
|
||||
|
||||
**保护边缘计算环境**
|
||||
|
||||
部署微型数据中心是规避上述风险的一个简单方法。（MDC）
|
||||
|
||||
“在历史上，大多数这些[边缘]环境都是不受控制的，”施耐德电气安全能源部门的首席技术官和创新高级副总裁 Kevin Brown 说。“它们可能是第一级，但很可能是第 0 级类型的设计-它们就像开放的配件柜。它们现在需要像微型数据中心一样的对待。你管理它需要像管理关键任务数据中心一样”
|
||||
|
||||
单说听起来的感觉，这个解决方案是一个安全，独立的机箱，它包括在室内和室外运行程序所需的所有存储空间，处理性能和网络资源。它同样包含必要的电源、冷却、安全和管理工具。
|
||||
|
||||
最重要的部分是高级别的安全性。这个装置是封闭的，有上锁的们，以防止非法入侵。通过合适的供应商，DMC 可以进行定制，包括用于远程数字化管理的监控摄像头、传感器和监控技术。
|
||||
|
||||
随着越来越多的公司开始利用边缘计算的优势，他们必须利用安全解决方案的优势来保护他们的数据和边缘环境。
|
||||
|
||||
在 APC.com 上了解保护你的边缘计算环境的最佳方案。
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.networkworld.com/article/3388130/enhanced-security-at-the-edge.html#tk.rss_all
|
||||
|
||||
作者：[Anne Taylor][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[hopefully2333](https://github.com/hopefully2333)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://www.networkworld.com/author/Anne-Taylor/
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://images.idgesg.net/images/article/2019/04/istock-1091707448-100793312-large.jpg
|
||||
[2]: https://www.csoonline.com/article/3250144/6-ways-hackers-will-use-machine-learning-to-launch-attacks.html
|
||||
[3]: https://www.marketwatch.com/press-release/edge-computing-market-2018-global-analysis-opportunities-and-forecast-to-2023-2018-08-20
|
||||
[4]: https://www.networkworld.com/article/3224893/what-is-edge-computing-and-how-it-s-changing-the-network.html
|
||||
[5]: https://www.youtube.com/watch?v=1NLk1cXEukQ
|
||||
[6]: https://www.apc.com/us/en/solutions/business-solutions/edge-computing.jsp
|
||||
@@ -0,0 +1,350 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( NeverKnowsTomorrow )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (Four Methods To Add A User To Group In Linux)
|
||||
[#]: via: (https://www.2daygeek.com/linux-add-user-to-group-primary-secondary-group-usermod-gpasswd/)
|
||||
[#]: author: (Magesh Maruthamuthu https://www.2daygeek.com/author/magesh/)
|
||||
|
||||
在 Linux 中添加用户到组的四个方法
|
||||
======
|
||||
|
||||
Linux 组是用于管理 Linux 中用户帐户的组织单位。
|
||||
|
||||
对于 Linux 系统中的每一个用户和组，它都有惟一的数字标识号。
|
||||
|
||||
它被称为 userid (UID) 和 groupid (GID)。组的主要目的是为组的成员定义一组特权。
|
||||
|
||||
它们都可以执行特定的操作，但不能执行其他操作。
|
||||
|
||||
Linux 中有两种类型的默认组可用。每个用户应该只有一个 <ruby>主要组<rt>primary group</rt></ruby> 和任意数量的 <ruby>次要组<rt>secondary group</rt></ruby>。
|
||||
|
||||
* **主要组：** 创建用户帐户时，已将主组添加到用户。它通常是用户的名称。在执行诸如创建新文件（或目录）、修改文件或执行命令等任何操作时，主组将应用于用户。用户主要组信息存储在 `/etc/passwd` 文件中。
|
||||
* **次要组：** 它被称为次要组。它允许用户组在同一组成员文件中执行特定操作。
|
||||
|
||||
例如，如果你希望允许少数用户运行 apache（httpd）服务命令，那么它将非常适合。
|
||||
|
||||
你可能对以下与用户管理相关的文章感兴趣。
|
||||
|
||||
* 在 Linux 中创建用户帐户的三种方法？
|
||||
* 如何在 Linux 中创建批量用户？
|
||||
* 如何在 Linux 中使用不同的方法更新/更改用户密码？
|
||||
|
||||
可以使用以下四种方法实现。
|
||||
|
||||
* **`usermod:`** usermod 命令修改系统帐户文件，以反映在命令行中指定的更改。
|
||||
* **`gpasswd:`** gpasswd 命令用于管理 /etc/group 和 /etc/gshadow。每个组都可以有管理员、成员和密码。
|
||||
* **`Shell Script:`** shell 脚本允许管理员自动执行所需的任务。
|
||||
* **`Manual Method:`** 我们可以通过编辑 `/etc/group` 文件手动将用户添加到任何组中。
|
||||
|
||||
我假设你已经拥有此活动所需的组和用户。在本例中，我们将使用以下用户和组：`user1`、`user2`、`user3`，group 是 `mygroup` 和 `mygroup1`。
|
||||
|
||||
在进行更改之前，我想检查用户和组信息。详见下文。
|
||||
|
||||
我可以看到下面的用户与他们自己的组关联，而不是与其他组关联。
|
||||
|
||||
```
|
||||
# id user1
|
||||
uid=1008(user1) gid=1008(user1) groups=1008(user1)
|
||||
|
||||
# id user2
|
||||
uid=1009(user2) gid=1009(user2) groups=1009(user2)
|
||||
|
||||
# id user3
|
||||
uid=1010(user3) gid=1010(user3) groups=1010(user3)
|
||||
```
|
||||
|
||||
我可以看到这个组中没有关联的用户。
|
||||
|
||||
```
|
||||
# getent group mygroup
|
||||
mygroup:x:1012:
|
||||
|
||||
# getent group mygroup1
|
||||
mygroup1:x:1013:
|
||||
```
|
||||
|
||||
### 方法 1：什么是 usermod 命令？
|
||||
|
||||
usermod 命令修改系统帐户文件，以反映命令行上指定的更改。
|
||||
|
||||
### 如何使用 usermod 命令将现有的用户添加到次要组或附加组？
|
||||
|
||||
要将现有用户添加到辅助组，请使用带有 `-g` 选项和组名称的 usermod 命令。
|
||||
|
||||
语法
|
||||
|
||||
```
|
||||
# usermod [-G] [GroupName] [UserName]
|
||||
```
|
||||
|
||||
如果系统中不存在给定的用户或组，你将收到一条错误消息。如果没有得到任何错误，那么用户已经被添加到相应的组中。
|
||||
|
||||
```
|
||||
# usermod -a -G mygroup user1
|
||||
```
|
||||
|
||||
让我使用 id 命令查看输出。是的，添加成功。
|
||||
|
||||
```
|
||||
# id user1
|
||||
uid=1008(user1) gid=1008(user1) groups=1008(user1),1012(mygroup)
|
||||
```
|
||||
|
||||
### 如何使用 usermod 命令将现有的用户添加到多个次要组或附加组？
|
||||
|
||||
要将现有用户添加到多个次要组中，请使用带有 `-G` 选项的 usermod 命令和带有逗号分隔的组名称。
|
||||
|
||||
语法
|
||||
|
||||
```
|
||||
# usermod [-G] [GroupName1,GroupName2] [UserName]
|
||||
```
|
||||
|
||||
在本例中，我们将把 `user2` 添加到 `mygroup` 和 `mygroup1` 中。
|
||||
|
||||
```
|
||||
# usermod -a -G mygroup,mygroup1 user2
|
||||
```
|
||||
|
||||
让我使用 `id` 命令查看输出。是的，`user2` 已成功添加到 `myGroup` 和 `myGroup1` 中。
|
||||
|
||||
```
|
||||
# id user2
|
||||
uid=1009(user2) gid=1009(user2) groups=1009(user2),1012(mygroup),1013(mygroup1)
|
||||
```
|
||||
|
||||
### 如何改变用户的主要组？
|
||||
|
||||
要更改用户的主要组，请使用带有 `-g` 选项和组名称的 usermod 命令。
|
||||
|
||||
语法
|
||||
|
||||
```
|
||||
# usermod [-g] [GroupName] [UserName]
|
||||
```
|
||||
|
||||
我们必须使用 `-g` 改变用户的主要组。
|
||||
|
||||
```
|
||||
# usermod -g mygroup user3
|
||||
```
|
||||
|
||||
让我们看看输出。是的，已成功更改。现在，它将 mygroup 显示为 user3 主要组而不是 user3。
|
||||
|
||||
```
|
||||
# id user3
|
||||
uid=1010(user3) gid=1012(mygroup) groups=1012(mygroup)
|
||||
```
|
||||
|
||||
### 方法 2：什么是 gpasswd 命令？
|
||||
|
||||
`gpasswd` 命令用于管理 `/etc/group` 和 `/etc/gshadow`。每个组都可以有管理员、成员和密码。
|
||||
|
||||
### 如何使用 gpasswd 命令将现有用户添加到次要组或者附加组？
|
||||
|
||||
要将现有用户添加到次要组，请使用带有 `-M` 选项和组名称的 gpasswd 命令。
|
||||
|
||||
语法
|
||||
|
||||
```
|
||||
# gpasswd [-M] [UserName] [GroupName]
|
||||
```
|
||||
|
||||
在本例中，我们将把 `user1 ` 添加到 `mygroup` 中。
|
||||
|
||||
```
|
||||
# gpasswd -M user1 mygroup
|
||||
```
|
||||
|
||||
让我使用 id 命令查看输出。是的，`user1` 已成功添加到 `mygroup` 中。
|
||||
|
||||
```
|
||||
# id user1
|
||||
uid=1008(user1) gid=1008(user1) groups=1008(user1),1012(mygroup)
|
||||
```
|
||||
|
||||
### 如何使用 gpasswd 命令添加多个用户到次要组或附加组中？
|
||||
|
||||
要将多个用户添加到辅助组中，请使用带有 `-M` 选项和组名称的 gpasswd 命令。
|
||||
|
||||
语法
|
||||
|
||||
```
|
||||
# gpasswd [-M] [UserName1,UserName2] [GroupName]
|
||||
```
|
||||
|
||||
在本例中，我们将把 `user2` 和 `user3` 添加到 `mygroup1` 中。
|
||||
|
||||
```
|
||||
# gpasswd -M user2,user3 mygroup1
|
||||
```
|
||||
|
||||
让我使用 getent 命令查看输出。是的，`user2` 和 `user3` 已成功添加到 `myGroup1` 中。
|
||||
|
||||
```
|
||||
# getent group mygroup1
|
||||
mygroup1:x:1013:user2,user3
|
||||
```
|
||||
|
||||
### 如何使用 gpasswd 命令从组中删除一个用户？
|
||||
|
||||
要从组中删除用户，请使用带有 `-d` 选项的 gpasswd 命令以及用户和组的名称。
|
||||
|
||||
语法
|
||||
|
||||
```
|
||||
# gpasswd [-d] [UserName] [GroupName]
|
||||
```
|
||||
|
||||
在本例中，我们将从 `mygroup` 中删除 `user1` 。
|
||||
|
||||
```
|
||||
# gpasswd -d user1 mygroup
|
||||
Removing user user1 from group mygroup
|
||||
```
|
||||
|
||||
### 方法 3：使用 Shell 脚本？
|
||||
|
||||
基于上面的例子，我知道 `usermod` 命令没有能力将多个用户添加到组中，但是可以通过 `gpasswd` 命令完成。
|
||||
|
||||
但是，它将覆盖当前与组关联的现有用户。
|
||||
|
||||
例如，`user1` 已经与 `mygroup` 关联。如果要使用 `gpasswd` 命令将 `user2` 和 `user3` 添加到 `mygroup` 中，它将不会按预期生效，而是对组进行修改。
|
||||
|
||||
如果要将多个用户添加到多个组中，解决方案是什么？
|
||||
|
||||
两个命令中都没有默认选项来实现这一点。
|
||||
|
||||
因此，我们需要编写一个小的 shell 脚本来实现这一点。
|
||||
|
||||
### 如何使用 gpasswd 命令将多个用户添加到次要组或附加组？
|
||||
|
||||
如果要使用 gpasswd 命令将多个用户添加到次要组或附加组，请创建以下小的 shell 脚本。
|
||||
|
||||
创建用户列表。每个用户应该在单独的行中。
|
||||
|
||||
```bash
|
||||
$ cat user-lists.txt
|
||||
user1
|
||||
user2
|
||||
user3
|
||||
```
|
||||
|
||||
使用以下 shell 脚本将多个用户添加到单个次要组。
|
||||
|
||||
```bash
|
||||
vi group-update.sh
|
||||
|
||||
#!/bin/bash
|
||||
for user in `cat user-lists.txt`
|
||||
do
|
||||
usermod -a -G mygroup $user
|
||||
done
|
||||
```
|
||||
|
||||
设置 `group-update.sh` 文件的可执行权限。
|
||||
|
||||
```
|
||||
# chmod + group-update.sh
|
||||
```
|
||||
|
||||
最后运行脚本来实现它。
|
||||
|
||||
```
|
||||
# sh group-update.sh
|
||||
```
|
||||
|
||||
让我看看使用 getent 命令的输出。 是的，`user1`，`user2` 和 `user3` 已成功添加到 `mygroup` 中。
|
||||
|
||||
```
|
||||
# getent group mygroup
|
||||
mygroup:x:1012:user1,user2,user3
|
||||
```
|
||||
|
||||
### 如何使用 gpasswd 命令将多个用户添加到多个次要组或附加组？
|
||||
|
||||
如果要使用 gpasswd 命令将多个用户添加到多个次要组或附加组中，请创建以下小的 shell 脚本。
|
||||
|
||||
创建用户列表。每个用户应该在单独的行中。
|
||||
|
||||
```bash
|
||||
$ cat user-lists.txt
|
||||
user1
|
||||
user2
|
||||
user3
|
||||
```
|
||||
|
||||
创建组列表。每组应在单独的行中。
|
||||
|
||||
```bash
|
||||
$ cat group-lists.txt
|
||||
mygroup
|
||||
mygroup1
|
||||
```
|
||||
|
||||
使用以下 shell 脚本将多个用户添加到多个次要组。
|
||||
|
||||
```bash
|
||||
#!/bin/sh
|
||||
for user in `more user-lists.txt`
|
||||
do
|
||||
for group in `more group-lists.txt`
|
||||
do
|
||||
usermod -a -G $group $user
|
||||
done
|
||||
```
|
||||
|
||||
设置 `group-update-1.sh` 文件的可执行权限。
|
||||
|
||||
```
|
||||
# chmod +x group-update-1.sh
|
||||
```
|
||||
|
||||
最后运行脚本来实现它。
|
||||
|
||||
```
|
||||
# sh group-update-1.sh
|
||||
```
|
||||
|
||||
让我看看使用 getent 命令的输出。 是的，`user1`，`user2` 和 `user3` 已成功添加到 `mygroup` 中。
|
||||
|
||||
```
|
||||
# getent group mygroup
|
||||
mygroup:x:1012:user1,user2,user3
|
||||
```
|
||||
|
||||
此外，`user1`，`user2` 和 `user3` 已成功添加到 `mygroup1` 中。
|
||||
|
||||
```
|
||||
# getent group mygroup1
|
||||
mygroup1:x:1013:user1,user2,user3
|
||||
```
|
||||
|
||||
### 方法 4：在 Linux 中将用户添加到组中的手动方法？
|
||||
|
||||
我们可以通过编辑 `/etc/group` 文件手动将用户添加到任何组中。
|
||||
|
||||
打开 `/etc/group` 文件并搜索要更新用户的组名。最后将用户更新到相应的组中。
|
||||
|
||||
```
|
||||
# vi /etc/group
|
||||
```
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.2daygeek.com/linux-add-user-to-group-primary-secondary-group-usermod-gpasswd/
|
||||
|
||||
作者：[Magesh Maruthamuthu][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[NeverKnowsTomorrow](https://github.com/NeverKnowsTomorrow)
|
||||
校对：[校对者 ID](https://github.com/校对者 ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux 中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://www.2daygeek.com/author/magesh/
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://www.2daygeek.com/linux-user-account-creation-useradd-adduser-newusers/
|
||||
[2]: https://www.2daygeek.com/how-to-create-the-bulk-users-in-linux/
|
||||
[3]: https://www.2daygeek.com/linux-passwd-chpasswd-command-set-update-change-users-password-in-linux-using-shell-script/
|
||||
Some files were not shown because too many files have changed in this diff Show More
Reference in New Issue
Block a user