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12 个最佳 GNOME（GTK）主题
======
> 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。
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。
### Ubuntu 和其它 Linux 发行版的最佳主题
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。
在这里列出的主题没有特别的次序。
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]。
#### 1、Arc-Ambiance
![][2]
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。
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。
- [下载 Arc-Ambiance 主题][3]
#### 2、Adapta Colorpack
![][4]
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！
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。
- [下载 Adapta Colorpack 主题][5]
#### 3、Numix Collection
![][6]
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。
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！
- [下载 Numix Collection 主题][7]
#### 4、Hooli
![][8]
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。
- [下载 Hooli 主题][9]
#### 5、Arrongin/Telinkrin
![][10]
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！
- [下载 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。
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。
- [下载 Gnome-osx 主题][14]
#### 7、Ultimate Maia
![][15]
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！
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？
- [下载 Ultimate Maia 主题][16]
#### 8、Vimix
![][17]
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。
- [下载 Vimix 主题][18]
#### 9、Ant
![][19]
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。
- [下载 Ant 主题][20]
#### 10、Flat Remix
![][21]
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。
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。
- [下载 Flat Remix 主题][22]
#### 11、Paper
![][23]
[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。
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。
- [下载 Paper 主题][25]
#### 12、Pop
![][26]
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。
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。
- [下载 Pop 主题][30]
#### 结束语
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！
--------------------------------------------------------------------------------
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

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[#]: 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。
![](https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/flightgear_cockpit_plane_sky.jpg?itok=LRy0lpOS)
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
![](https://opensource.com/sites/default/files/uploads/flightgear_menu.png)
**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。
![](https://opensource.com/sites/default/files/uploads/flightgear_aircraft.png)
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。
![](https://opensource.com/sites/default/files/uploads/flightgear_cockpit-view.png)
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

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[#]: 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

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[#]: 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

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[#]: 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。
![](https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/reading_book_stars_list.png?itok=Iwa1oBOl)
[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

19
translated/tech/20190312 Do advanced math with Mathematica on the Raspberry Pi.md → published/20190312 Do advanced math with Mathematica on the Raspberry Pi.md
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@@ -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。
![](https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/edu_math_formulas.png?itok=B59mYTG3)
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/

56
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@@ -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

144
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@@ -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

34
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@@ -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
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@@ -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/

50
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@@ -1,26 +1,28 @@
[#]: collector: (lujun9972)
[#]: translator: (liujing97)
[#]: reviewer: ( )
[#]: publisher: ( )
[#]: url: ( )
[#]: reviewer: (wxy)
[#]: publisher: (wxy)
[#]: url: (https://linux.cn/article-10705-1.html)
[#]: subject: (How to create a filesystem on a Linux partition or logical volume)
[#]: via: (https://opensource.com/article/19/4/create-filesystem-linux-partition)
[#]: 作者: (Kedar Vijay Kulkarni (Red Hat) https://opensource.com/users/kkulkarn)
如何在 Linux 分区或逻辑卷中创建文件系统
======
学习在你的系统中创建一个文件系统，并且长期或者非长期地挂载它。
> 学习在你的系统中创建一个文件系统，并且长期或者非长期地挂载它。
![Filing papers and documents][1]
在计算技术中，文件系统控制如何存储和检索数据，并且帮助组织存储媒介中的文件。如果没有文件系统，信息将被存储为一个大数据块，而且你无法知道一条信息在哪结束，下一条信息在哪开始。文件系统通过为存储数据的文件提供名称，并且在文件系统中的磁盘上维护文件和目录表以及它们的开始和结束位置，总的大小等来帮助管理所有的这些信息。
在计算技术中，文件系统控制如何存储和检索数据，并且帮助组织存储媒介中的文件。如果没有文件系统，信息将被存储为一个大数据块，而且你无法知道一条信息在哪结束，下一条信息在哪开始。文件系统通过为存储数据的文件提供名称，并且在文件系统中的磁盘上维护文件和目录表以及它们的开始和结束位置、总的大小等来帮助管理所有的这些信息。
在 Linux 中，当你创建一个硬盘分区或者逻辑卷之后，接下来通常是通过格式化这个分区或逻辑卷来创建文件系统。这个操作方法假设你已经知道如何创建分区或逻辑卷，并且你希望将它格式化为包含有文件系统，并且挂载它。
### 创建文件系统
假设你为你的系统添加了一块新的硬盘并且在它上面创建了一个叫 **/dev/sda1** 的分区。
假设你为你的系统添加了一块新的硬盘并且在它上面创建了一个叫 `/dev/sda1` 的分区。
1. 为了验证 Linux 内核已经发现这个分区，你可以 **cat** 出 **/proc/partitions** 的内容，就像这样：
1、为了验证 Linux 内核已经发现这个分区，你可以 `cat` 出 `/proc/partitions` 的内容，就像这样：
```
[root@localhost ~]# cat /proc/partitions
@@ -39,7 +41,7 @@ major minor #blocks name
```
2. 决定你想要去创建的文件系统种类，比如 ext4, XFS，或者其他的一些。这里是一些选项：
2、决定你想要去创建的文件系统种类，比如 ext4、XFS，或者其他的一些。这里是一些可选项：
```
[root@localhost ~]# mkfs.<tab><tab>
@@ -47,7 +49,7 @@ mkfs.btrfs mkfs.cramfs mkfs.ext2 mkfs.ext3 mkfs.ext4 mkfs.minix mkfs.xfs
```
3. 为了这次练习的目的，选择 ext4。（我喜欢 ext4 因为如果你需要的话，它可以允许你去压缩文件系统，这对于 XFS 并不简单。）这里是完成它的方法（输出可能会因设备名称或者大小而不同）：
3、为了这次练习的目的，选择 ext4。（我喜欢 ext4，因为如果你需要的话，它可以允许你去压缩文件系统，这对于 XFS 并不简单。）这里是完成它的方法（输出可能会因设备名称或者大小而不同）：
```
[root@localhost ~]# mkfs.ext4 /dev/sda1
@@ -73,18 +75,16 @@ Creating journal (16384 blocks): done
Writing superblocks and filesystem accounting information: done
```
4. 在上一步中，如果你想去创建不同的文件系统，请使用不同变种的 **mkfs** 命令。
4、在上一步中，如果你想去创建不同的文件系统，请使用不同变种的 `mkfs` 命令。
### 挂载文件系统
当你创建好文件系统后，你可以在你的操作系统中挂载它。
1. 首先，识别出新文件系统的 UUID 号。使用 **blkid** 命令列出所有可识别的块存储设备并且在输出信息中查找 **sda1**：
1、首先，识别出新文件系统的 UUID 编码。使用 `blkid` 命令列出所有可识别的块存储设备并且在输出信息中查找 `sda1`：
```
[root@localhost ~]# blkid
[root@localhost ~]# blkid
/dev/vda1: UUID="716e713d-4e91-4186-81fd-c6cfa1b0974d" TYPE="xfs"
/dev/sr1: UUID="2019-03-08-16-17-02-00" LABEL="config-2" TYPE="iso9660"
/dev/sda1: UUID="wow9N8-dX2d-ETN4-zK09-Gr1k-qCVF-eCerbF" TYPE="LVM2_member"
@@ -93,11 +93,10 @@ Writing superblocks and filesystem accounting information: done
[root@localhost ~]#
```
2. 运行下面的命令挂载 **/dev/sd1** 设备：
2、运行下面的命令挂载 `/dev/sd1` 设备：
```
[root@localhost ~]# mkdir /mnt/mount_point_for_dev_sda1
[root@localhost ~]# mkdir /mnt/mount_point_for_dev_sda1
[root@localhost ~]# ls /mnt/
mount_point_for_dev_sda1
[root@localhost ~]# mount -t ext4 /dev/sda1 /mnt/mount_point_for_dev_sda1/
@@ -112,19 +111,16 @@ tmpfs 93M 0 93M 0% /run/user/0
/dev/sda1 2.9G 9.0M 2.7G 1% /mnt/mount_point_for_dev_sda1
[root@localhost ~]#
```
命令 **df -h** 显示了每个文件系统被挂载的挂载点。查找 **/dev/sd1**。上面的挂载命令使用的设备名称是 **/dev/sda1**。用 **blkid** 命令中的 UUID 号替换它。注意，在 **/mnt** 下一个被新创建的目录挂载了 **/dev/sda1**。
命令 `df -h` 显示了每个文件系统被挂载的挂载点。查找 `/dev/sd1`。上面的挂载命令使用的设备名称是 `/dev/sda1`。用 `blkid` 命令中的 UUID 编码替换它。注意，在 `/mnt` 下一个被新创建的目录挂载了 `/dev/sda1`。
3. 直接在命令行下使用挂载命令（就像上一步一样）会有一个问题，那就是挂载不会在设备重启后存在。为使永久性地挂载文件系统，编辑 **/etc/fstab** 文件去包含你的挂载信息：
3、直接在命令行下使用挂载命令（就像上一步一样）会有一个问题，那就是挂载不会在设备重启后存在。为使永久性地挂载文件系统，编辑 `/etc/fstab` 文件去包含你的挂载信息：
```
UUID=ac96b366-0cdd-4e4c-9493-bb93531be644 /mnt/mount_point_for_dev_sda1/ ext4 defaults 0 0
```
4. 编辑完 **/etc/fstab** 文件后，你可以 **umount /mnt/mount_point_for_fev_sda1** 并且运行 **mount -a** 命令去挂载被列在 **/etc/fstab** 文件中的所有设备文件。如果一切顺利的话，你可以使用 **df -h** 列出并且查看你挂载的文件系统：
4、编辑完 `/etc/fstab` 文件后，你可以 `umount /mnt/mount_point_for_fev_sda1` 并且运行 `mount -a` 命令去挂载被列在 `/etc/fstab` 文件中的所有设备文件。如果一切顺利的话，你可以使用 `df -h` 列出并且查看你挂载的文件系统：
```
root@localhost ~]# umount /mnt/mount_point_for_dev_sda1/
@@ -140,25 +136,23 @@ tmpfs 93M 0 93M 0% /run/user/0
/dev/sda1 2.9G 9.0M 2.7G 1% /mnt/mount_point_for_dev_sda1
```
5. 你也可以检测文件系统是否被挂载：
5、你也可以检测文件系统是否被挂载：
```
[root@localhost ~]# mount | grep ^/dev/sd
/dev/sda1 on /mnt/mount_point_for_dev_sda1 type ext4 (rw,relatime,seclabel,stripe=8191,data=ordered)
```
现在你已经知道如何去创建文件系统并且长期或者非长期的挂载在你的系统中。
--------------------------------------------------------------------------------
via: https://opensource.com/article/19/4/create-filesystem-linux-partition
作者：[Kedar Vijay Kulkarni (Red Hat)][a]
作者：[Kedar Vijay Kulkarni][a]
选题：[lujun9972][b]
译者：[liujing97](https://github.com/liujing97)
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[#]: collector: (lujun9972)
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[#]: 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.
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[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
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[#]: 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.
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[4]: https://cloud.google.com/blog/topics/hybrid-cloud/new-platform-for-managing-applications-in-todays-multi-cloud-world
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[#]: 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.
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translating by robsean
12 Best GTK Themes for Ubuntu and other Linux Distributions
======
**Brief: Let’s have a look at some of the beautiful GTK themes that you can use not only in Ubuntu but other Linux distributions that use GNOME.**
For those of us that use Ubuntu proper, the move from Unity to Gnome as the default desktop environment has made theming and customizing easier than ever. Gnome has a fairly large tweaking community, and there is no shortage of fantastic GTK themes for users to choose from. With that in mind, I went ahead and found some of my favorite themes that I have come across in recent months. These are what I believe offer some of the best experiences that you can find.
### Best themes for Ubuntu and other Linux distributions
This is not an exhaustive list and may exclude some of the themes you already use and love, but hopefully, you find at least one theme that you enjoy that you did not already know about. All themes present should work on any Gnome 3 setup, Ubuntu or not. I lost some screenshots so I have taken images from the official websites.
The themes listed here are in no particular order.
But before you see the best GNOME themes, you should learn [how to install themes in Ubuntu GNOME][1].
#### 1\. Arc-Ambiance
![][2]
Arc and Arc variant themes have been around for quite some time now, and are widely regarded as some of the best themes you can find. In this example, I have selected Arc-Ambiance because of its modern take on the default Ambiance theme in Ubuntu.
I am a fan of both the Arc theme and the default Ambiance theme, so needless to say, I was pumped when I came across a theme that merged the best of both worlds. If you are a fan of the arc themes but not a fan of this one in particular, Gnome look has plenty of other options that will most certainly suit your taste.
[Arc-Ambiance Theme][3]
#### 2\. Adapta Colorpack
![][4]
The Adapta theme has been one of my favorite flat themes I have ever found. Like Arc, Adapata is widely adopted by many-a-linux user. I have selected this color pack because in one download you have several options to choose from. In fact, there are 19 to choose from. Yep. You read that correctly. 19!
So, if you are a fan of the flat/material design language that we see a lot of today, then there is most likely a variant in this theme pack that will satisfy you.
[Adapta Colorpack Theme][5]
#### 3\. Numix Collection
![][6]
Ah, Numix! Oh, the years we have spent together! For those of us that have been theming our DE for the last couple of years, you must have come across the Numix themes or icon packs at some point in time. Numix was probably the first modern theme for Linux that I fell in love with, and I am still in love with it today. And after all these years, it still hasn’t lost its charm.
The gray tone throughout the theme, especially with the default pinkish-red highlight color, makes for a genuinely clean and complete experience. You would be hard pressed to find a theme pack as polished as Numix. And in this offering, you have plenty of options to choose from, so go crazy!
[Numix Collection Theme][7]
#### 4\. Hooli
![][8]
Hooli is a theme that has been out for some time now, but only recently came across my radar. I am a fan of most flat themes but have usually strayed away from themes that come to close to the material design language. Hooli, like Adapta, takes notes from that design language, but does it in a way that I think sets it apart from the rest. The green highlight color is one of my favorite parts about the theme, and it does a good job at not overpowering the entire theme.
[Hooli Theme][9]
#### 5\. Arrongin/Telinkrin
![][10]
Bonus: Two themes in one! And they are relatively new contenders in the theming realm. They both take notes from Ubuntu’s soon to be finished “[communitheme][11]” and bring it to your desktop today. The only real difference I can find between the offerings are the colors. Arrongin is centered around an Ubuntu-esq orange color, while Telinkrin uses a slightly more KDE Breeze-esq blue. I personally prefer the blue, but both are great options!
[Arrongin/Telinkrin Themes][12]
#### 6\. Gnome-osx
![][13]
I have to admit, usually, when I see that a theme has “osx” or something similar in the title, I don’t expect much. Most Apple inspired themes seem to have so much in common that I can’t really find a reason to use them. There are two themes I can think of that break this mold: the Arc-osc them and the Gnome-osx theme that we have here.
The reason I like the Gnome-osx theme is because it truly does look at home on the Gnome desktop. It does a great job at blending into the DE without being too flat. So for those of you that enjoy a slightly less flat theme, and you like the red, yellow, and green button scheme for the close, minimize, and maximize buttons, than this theme is perfect for you.
[Gnome-osx Theme][14]
#### 7\. Ultimate Maia
![][15]
There was a time when I used Manjaro Gnome. Since then I have reverted back to Ubuntu, but one thing I wish I could have brought with me was the Manjaro theme. If you feel the same about the Manjaro theme as I do, then you are in luck because you can bring it to ANY distro you want that is running Gnome!
The rich green color, the Breeze-esq close, minimize, maximize buttons, and the over-all polish of the theme makes for one compelling option. It even offers some other color variants of you are not a fan of the green. But let’s be honest…who isn’t a fan of that Manjaro green color?
[Ultimate Maia Theme][16]
#### 8\. Vimix
![][17]
This was a theme I easily got excited about. It is modern, pulls from the macOS red, yellow, green buttons without directly copying them, and tones down the vibrancy of the theme, making for one unique alternative to most other themes. It comes with three dark variants and several colors to choose from so most of us will find something we like.
[Vimix Theme][18]
#### 9\. Ant
![][19]
Like Vimix, Ant pulls inspiration from macOS for the button colors without directly copying the style. Where Vimix tones down the color options, Ant adds a richness to the colors that looks fantastic on my System 76 Galago Pro screen. The variation between the three theme options is pretty dramatic, and though it may not be to everyone’s taste, it is most certainly to mine.
[Ant Theme][20]
#### 10\. Flat Remix
![][21]
If you haven’t noticed by this point, I am a sucker for someone who pays attention to the details in the close, minimize, maximize buttons. The color theme that Flat Remix uses is one I have not seen anywhere else, with a red, blue, and orange color way. Add that on top of a theme that looks almost like a mix between Arc and Adapta, and you have Flat Remix.
I am personally a fan of the dark option, but the light alternative is very nice as well. So if you like subtle transparencies, a cohesive dark theme, and a touch of color here and there, Flat Remix is for you.
[Flat Remix Theme][22]
#### 11\. Paper
![][23]
[Paper][24] has been around for some time now. I remember using it for the first back in 2014. I would say, at this point, Paper is more known for its icon pack than for its GTK theme, but that doesn’t mean that the theme isn’t a wonderful option in and of its self. Even though I adored the Paper icons from the beginning, I can’t say that I was a huge fan of the Paper theme when I first tried it out.
I felt like the bright colors and fun approach to a theme made for an “immature” experience. Now, years later, Paper has grown on me, to say the least, and the light hearted approach that the theme takes is one I greatly appreciate.
[Paper Theme][25]
#### 12\. Pop
![][26]
Pop is one of the newer offerings on this list. Created by the folks over at [System 76][27], the Pop GTK theme is a fork of the Adapta theme listed earlier and comes with a matching icon pack, which is a fork of the previously mentioned Paper icon pack.
The theme was released soon after System 76 announced that they were releasing [their own distribution,][28] Pop!_OS. You can read my [Pop!_OS review][29] to know more about it. Needless to say, I think Pop is a fantastic theme with a superb amount of polish and offers a fresh feel to any Gnome desktop.
[Pop Theme][30]
#### Conclusion
Obviously, there way more themes to choose from than we could feature in one article, but these are some of the most complete and polished themes I have used in recent months. If you think we missed any that you really like or you just really dislike one that I featured above, then feel free to let me know in the comment section below and share why you think your favorite themes are better!
--------------------------------------------------------------------------------
via: https://itsfoss.com/best-gtk-themes/
作者：[Phillip Prado][a]
译者：[译者ID](https://github.com/译者ID)
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

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translating by MjSeven
Getting started with Sensu monitoring
======
![](https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/rh_003601_05_mech_osyearbook2016_cloud_cc.png?itok=XSV7yR9e)

1
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liujing97 is translating
Working with data streams on the Linux command line
======
Learn to connect data streams from one utility to another using STDIO.

359
sources/tech/20190108 How To Understand And Identify File types in Linux.md
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[#]: 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

159
sources/tech/20190129 7 Methods To Identify Disk Partition-FileSystem UUID On Linux.md
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@@ -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/

74
sources/tech/20190211 Ubuntu 14.04 is Reaching the End of Life. Here are Your Options.md
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@@ -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

54
sources/tech/20190313 How to contribute to the Raspberry Pi community.md Normal file
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@@ -0,0 +1,54 @@
[#]: collector: (lujun9972)
[#]: translator: (geekpi)
[#]: reviewer: ( )
[#]: publisher: ( )
[#]: url: ( )
[#]: 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)
How to contribute to the Raspberry Pi community
======
Find ways to get involved in the Raspberry Pi community in the 13th
article in our getting-started series.
![][1]
Things are starting to wind down in this series, and as much fun as I've had writing it, mostly I hope it has helped someone out there use start using a Raspberry Pi for education or entertainment. Maybe the articles convinced you to buy your first Raspberry Pi or perhaps helped you rediscover the device that was collecting dust in a drawer. If any of that is true, I'll consider the series a success.
If you now want to pay it forward and help spread the word on how versatile this little green digital board is, here are a few ways you can get connected to the Raspberry Pi community:
* Contribute to improving the [official documentation][2]
* Contribute code to [projects][3] the Raspberry Pi depends on
* File [bugs][4] with Raspbian
* File bugs with the different ARM architecture platform distributions
* Help kids learn to code by taking a look at the Raspberry Pi Foundation's [Code Club][5] in the UK or [Code Club International][6] outside the UK
* Help with [translation][7]
* Volunteer on a [Raspberry Jam][8]
These are just a few of the ways you can contribute to the Raspberry Pi community. Last but not least, you can join me and [contribute articles][9] to your favorite open source website, [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：[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/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

301
sources/tech/20190317 How To Configure sudo Access In Linux.md
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@@ -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

188
sources/tech/20190321 How To Check If A Port Is Open On Multiple Remote Linux System Using Shell Script With nc Command.md
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@@ -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/

154
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[#]: 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

70
sources/tech/20190401 3 cool text-based email clients.md
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@@ -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/

2
sources/tech/20190402 Using Square Brackets in Bash- Part 2.md
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[#]: collector: (lujun9972)
[#]: translator: ( )
[#]: translator: (HankChow)
[#]: reviewer: ( )
[#]: publisher: ( )
[#]: url: ( )

124
sources/tech/20190403 5 useful open source log analysis tools.md
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@@ -1,124 +0,0 @@
[#]: collector: (lujun9972)
[#]: translator: (MjSeven)
[#]: reviewer: ( )
[#]: publisher: ( )
[#]: url: ( )
[#]: subject: (5 useful open source log analysis tools)
[#]: via: (https://opensource.com/article/19/4/log-analysis-tools)
[#]: author: (Sam Bocetta https://opensource.com/users/sambocetta)
5 useful open source log analysis tools
======
Monitoring network activity is as important as it is tedious. These
tools can make it easier.
![People work on a computer server][1]
Monitoring network activity can be a tedious job, but there are good reasons to do it. For one, it allows you to find and investigate suspicious logins on workstations, devices connected to networks, and servers while identifying sources of administrator abuse. You can also trace software installations and data transfers to identify potential issues in real time rather than after the damage is done.
Those logs also go a long way towards keeping your company in compliance with the [General Data Protection Regulation][2] (GDPR) that applies to any entity operating within the European Union. If you have a website that is viewable in the EU, you qualify.
Logging—both tracking and analysis—should be a fundamental process in any monitoring infrastructure. A transaction log file is necessary to recover a SQL server database from disaster. Further, by tracking log files, DevOps teams and database administrators (DBAs) can maintain optimum database performance or find evidence of unauthorized activity in the case of a cyber attack. For this reason, it's important to regularly monitor and analyze system logs. It's a reliable way to re-create the chain of events that led up to whatever problem has arisen.
There are quite a few open source log trackers and analysis tools available today, making choosing the right resources for activity logs easier than you think. The free and open source software community offers log designs that work with all sorts of sites and just about any operating system. Here are five of the best I've used, in no particular order.
### Graylog
[Graylog][3] started in Germany in 2011 and is now offered as either an open source tool or a commercial solution. It is designed to be a centralized log management system that receives data streams from various servers or endpoints and allows you to browse or analyze that information quickly.
![Graylog screenshot][4]
Graylog has built a positive reputation among system administrators because of its ease in scalability. Most web projects start small but can grow exponentially. Graylog can balance loads across a network of backend servers and handle several terabytes of log data each day.
IT administrators will find Graylog's frontend interface to be easy to use and robust in its functionality. Graylog is built around the concept of dashboards, which allows you to choose which metrics or data sources you find most valuable and quickly see trends over time.
When a security or performance incident occurs, IT administrators want to be able to trace the symptoms to a root cause as fast as possible. Search functionality in Graylog makes this easy. It has built-in fault tolerance that can run multi-threaded searches so you can analyze several potential threats together.
### Nagios
[Nagios][5] started with a single developer back in 1999 and has since evolved into one of the most reliable open source tools for managing log data. The current version of Nagios can integrate with servers running Microsoft Windows, Linux, or Unix.
![Nagios Core][6]
Its primary product is a log server, which aims to simplify data collection and make information more accessible to system administrators. The Nagios log server engine will capture data in real-time and feed it into a powerful search tool. Integrating with a new endpoint or application is easy thanks to the built-in setup wizard.
Nagios is most often used in organizations that need to monitor the security of their local network. It can audit a range of network-related events and help automate the distribution of alerts. Nagios can even be configured to run predefined scripts if a certain condition is met, allowing you to resolve issues before a human has to get involved.
As part of network auditing, Nagios will filter log data based on the geographic location where it originates. That means you can build comprehensive dashboards with mapping technology to understand how your web traffic is flowing.
### Elastic Stack (the "ELK Stack")
[Elastic Stack][7], often called the ELK Stack, is one of the most popular open source tools among organizations that need to sift through large sets of data and make sense of their system logs (and it's a personal favorite, too).
![ELK Stack][8]
Its primary offering is made up of three separate products: Elasticsearch, Kibana, and Logstash:
* As its name suggests, _**Elasticsearch**_ is designed to help users find matches within datasets using a wide range of query languages and types. Speed is this tool's number one advantage. It can be expanded into clusters of hundreds of server nodes to handle petabytes of data with ease.
* _**Kibana**_ is a visualization tool that runs alongside Elasticsearch to allow users to analyze their data and build powerful reports. When you first install the Kibana engine on your server cluster, you will gain access to an interface that shows statistics, graphs, and even animations of your data.
* The final piece of ELK Stack is _**Logstash**_ , which acts as a purely server-side pipeline into the Elasticsearch database. You can integrate Logstash with a variety of coding languages and APIs so that information from your websites and mobile applications will be fed directly into your powerful Elastic Stalk search engine.
A unique feature of ELK Stack is that it allows you to monitor applications built on open source installations of WordPress. In contrast to most out-of-the-box security audit log tools that [track admin and PHP logs][9] but little else, ELK Stack can sift through web server and database logs.
Poor log tracking and database management are one of the [most common causes of poor website performance][10]. Failure to regularly check, optimize, and empty database logs can not only slow down a site but could lead to a complete crash as well. Thus, the ELK Stack is an excellent tool for every WordPress developer's toolkit.
### LOGalyze
[LOGalyze][11] is an organization based in Hungary that builds open source tools for system administrators and security experts to help them manage server logs and turn them into useful data points. Its primary product is available as a free download for either personal or commercial use.
![LOGalyze][12]
LOGalyze is designed to work as a massive pipeline in which multiple servers, applications, and network devices can feed information using the Simple Object Access Protocol (SOAP) method. It provides a frontend interface where administrators can log in to monitor the collection of data and start analyzing it.
From within the LOGalyze web interface, you can run dynamic reports and export them into Excel files, PDFs, or other formats. These reports can be based on multi-dimensional statistics managed by the LOGalyze backend. It can even combine data fields across servers or applications to help you spot trends in performance.
LOGalyze is designed to be installed and configured in less than an hour. It has prebuilt functionality that allows it to gather audit data in formats required by regulatory acts. For example, LOGalyze can easily run different HIPAA reports to ensure your organization is adhering to health regulations and remaining compliant.
### Fluentd
If your organization has data sources living in many different locations and environments, your goal should be to centralize them as much as possible. Otherwise, you will struggle to monitor performance and protect against security threats.
[Fluentd][13] is a robust solution for data collection and is entirely open source. It does not offer a full frontend interface but instead acts as a collection layer to help organize different pipelines. Fluentd is used by some of the largest companies worldwide but can be implemented in smaller organizations as well.
![Fluentd architecture][14]
The biggest benefit of Fluentd is its compatibility with the most common technology tools available today. For example, you can use Fluentd to gather data from web servers like Apache, sensors from smart devices, and dynamic records from MongoDB. What you do with that data is entirely up to you.
Fluentd is based around the JSON data format and can be used in conjunction with [more than 500 plugins][15] created by reputable developers. This allows you to extend your logging data into other applications and drive better analysis from it with minimal manual effort.
### The bottom line
If you aren't already using activity logs for security reasons, governmental compliance, and measuring productivity, commit to changing that. There are plenty of plugins on the market that are designed to work with multiple environments and platforms, even on your internal network. Don't wait for a serious incident to justify taking a proactive approach to logs maintenance and oversight.
--------------------------------------------------------------------------------
via: https://opensource.com/article/19/4/log-analysis-tools
作者：[Sam Bocetta][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/sambocetta
[b]: https://github.com/lujun9972
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/rh_003499_01_linux11x_cc.png?itok=XMDOouJR (People work on a computer server)
[2]: https://opensource.com/article/18/4/gdpr-impact
[3]: https://www.graylog.org/products/open-source
[4]: https://opensource.com/sites/default/files/uploads/graylog-data.png (Graylog screenshot)
[5]: https://www.nagios.org/downloads/
[6]: https://opensource.com/sites/default/files/uploads/nagios_core_4.0.8.png (Nagios Core)
[7]: https://www.elastic.co/products
[8]: https://opensource.com/sites/default/files/uploads/elk-stack.png (ELK Stack)
[9]: https://www.wpsecurityauditlog.com/benefits-wordpress-activity-log/
[10]: https://websitesetup.org/how-to-speed-up-wordpress/
[11]: http://www.logalyze.com/
[12]: https://opensource.com/sites/default/files/uploads/logalyze.jpg (LOGalyze)
[13]: https://www.fluentd.org/
[14]: https://opensource.com/sites/default/files/uploads/fluentd-architecture.png (Fluentd architecture)
[15]: https://opensource.com/article/18/9/open-source-log-aggregation-tools

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sources/tech/20190405 Streaming internet radio with RadioDroid.md
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[#]: 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

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[#]: 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

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[#]: 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/

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[#]: 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

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[#]: 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/

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[#]: 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

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[#]: 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/)
Cisco, Google reenergize multicloud/hybrid cloud joint development
======
Cisco, VMware, HPE and others tap into new Google Cloud Athos cloud technology
![Thinkstock][1]
Cisco and Google have expanded their joint cloud-development activities to help customers more easily build secure multicloud and hybrid applications everywhere from on-premises data centers to public clouds.
**[Check out[what hybrid cloud computing is][2] and learn [what you need to know about multi-cloud][3]. Get regularly scheduled insights by [signing up for Network World newsletters][4]]**
The expansion centers around Google’s new open-source hybrid cloud package called Anthos, which was introduced at the company’s Google Next event this week. Anthos is based on – and supplants – the company's existing Google Cloud Service beta. Anthos will let customers run applications, unmodified, on existing on-premises hardware or in the public cloud and will be available on [Google Cloud Platform][5] (GCP) with [Google Kubernetes Engine][6] (GKE), and in data centers with [GKE On-Prem][7], the company says. Anthos will also let customers for the first time manage workloads running on third-party clouds such as AWS and Azure from the Google platform without requiring administrators and developers to learn different environments and APIs, Google said.
Essentially, Athos offers a single managed service that promises to let customers manage and deploy workloads across clouds, without having to worry about dissimilar environments or APIs.
As part of the rollout, Google also announced a beta program called[ Anthos Migrate][8] that Google says auto-migrates VMs from on-premises, or other clouds, directly into containers in GKE. “This unique migration technology lets you migrate and modernize your infrastructure in one streamlined motion, without upfront modifications to the original VMs or applications,” Google said. It gives companies the flexibility to move on-prem apps to a cloud environment at the customers pace, Google said.
### Cisco and Google
For its part Cisco announced support of Anthos and promised to tightly integrate it with Cisco data center-technologies, such as its HyperFlex hyperconverged package, Application Centric Infrastructure (Cisco’s flagship SDN offering), SD-WAN and Stealthwatch Cloud. The integrations will enable a consistent, cloud-like experience whether on-prem or in the cloud with automatic upgrades to the latest versions and security patches, Cisco stated.
"Google Cloud’s expertise in containerization and service mesh – Kubernetes and Istio, respectively – as well as their leadership in the developer community, combined with Cisco’s enterprise-class networking, compute, storage and security products and services makes for a winning combination for our customers," [wrote][9] Kip Compton, Cisco senior vice president, Cloud Platform and Solutions Group. “The Cisco integrations for Anthos will help customers build and manage multicloud and hybrid applications across their on-premises datacenters and public clouds and let them focus on innovation and agility without compromising security or increasing complexity.”
### Google Cloud and Cisco
Eyal Manor, vice president, engineering at Google Cloud, [wrote][10] that with Cisco’s support for Anthos, customers will be able to:
* Benefit from a fully-managed service, like GKE, and Cisco’s hyperconverged infrastructure, networking, and security technologies.
* Operate consistently across an enterprise data center and the cloud.
* Consume cloud services from an enterprise data center.
* Modernize now on premises with the latest cloud technologies.
Cisco and Google have been working closely together since October 2017, when the companies said they were working on an open hybrid cloud platform that bridges on-premises and cloud environments. That package, [Cisco Hybrid Cloud Platform for Google Cloud][11], became generally available in September 2018. It lets customer develop enterprise-grade capabilities from Google Cloud-managed Kubernetes containers that include Cisco networking and security technology as well as service mesh monitoring from Istio.
Google says Istio’s open-source, container- and microservice-optimized technology offers developers a uniform way to connect, secure, manage and monitor microservices across clouds through service-to-service level mTLS [Mutual Transport Layer Security] authentication access control. As a result, customers can easily implement new, portable services and centrally configure and manage those services.
Cisco wasn’t the only vendor to announce support for Anthos. At least 30 other big Google partners including [VMware][12], [Dell EMC][13], [HPE][14], Intel, and Lenovo committed to delivering Anthos on their own hyperconverged infrastructure for their customers, Google stated.
Join the Network World communities on [Facebook][15] and [LinkedIn][16] to comment on topics that are top of mind.
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作者：[Michael Cooney][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://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

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[#]: collector: (lujun9972)
[#]: translator: ( )
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[#]: 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/)
Enhanced security at the edge
======
The risks presented by edge computing environments necessitates that companies pay special attention to security measures.
![iStock][1]
It’s becoming a cliché to say that data security is a top concern among executives and boards of directors. The problem is: the problem just won’t go away.
Hackers and attackers are ever finding new ways to exploit weaknesses. Just as companies start to use emerging technologies like artificial intelligence and machine learning to protect their organizations in an automated fashion, [so too are bad actors][2] using these tools to further their goals.
In a nutshell, security simply cannot be overlooked. And now, as companies [increasingly adopt][3] edge computing, there are new considerations to securing these environments.
**More risks at the edge**
As a [Network World article][4] suggests, edge computing places a new focus on physical security. That’s not to dismiss the need to secure data in transit. However, it’s the actual physical sites and equipment that deserve special attention.
For example, edge hardware is often situated in larger corporate or wide-open spaces, sometimes in highly accessible, shared offices and public areas. Ostensibly, this is to take advantage of the cost savings and faster access associated with data not having to travel back and forth to the data center.
However, without any level of access control, this equipment is at risk of both malicious actions and simple human error. Imagine an office cleaner accidentally turning off a device, and the resulting effects of subsequent downtime.
Another risk is “Shadow edge IT.” Sometimes non-IT staff will deploy an edge site to quickly launch a project, without letting the IT department know this site is now connecting to the network. For example, a retail store might take the initiative to install its own digital signage. Or, a sales team could apply IoT sensors to TVs and deployed them on-the-fly at a sales demo.
In these cases, IT may have little or no visibility into these devices and edge sites, leaving the network potentially exposed.
**Securing the edge**
An easy way to avoid these risks is to deploy a micro data center (MDC).
> “Most of these [edge] environments have historically been uncontrolled,” [said Kevin Brown][5], SVP Innovation and CTO for Schneider Electric’s Secure Power Division. “They might be a Tier 1, but likely a Tier 0 type of design — they’re like open wiring closets. They now need to be treated like micro data centers. You need to be able to manage them as you would a mission-critical data center.”
Just as it sounds, this solution is a secure, self-contained enclosure that includes all the storage, processing, and networking that’s required to run applications both indoors and outdoors. It also includes the necessary power, cooling, security, and management tools.
The best part is the high level of security. The unit is enclosed, with locking doors, to prevent unauthorized access. And with the right vendor, the MDC can be customized to include surveillance cameras, sensors, and monitoring technology for remote digital management.
As companies increasingly take advantage of the benefits of edge computing, it’s critical they also take advantage of security solutions to protect their data and environments.
Discover how to best secure your edge computing environment at [APC.com][6].
--------------------------------------------------------------------------------
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：[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/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

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[#]: 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.
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作者：[Michael Cooney][a]
选题：[lujun9972][b]
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[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

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[#]: 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.
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作者：[Fredric Paul][a]
选题：[lujun9972][b]
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[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

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[#]: 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/

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[#]: 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

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[#]: 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/

101
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[#]: 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

94
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[#]: collector: (lujun9972)
[#]: translator: ( )
[#]: reviewer: ( )
[#]: publisher: ( )
[#]: url: ( )
[#]: subject: (Managing Partitions with sgdisk)
[#]: via: (https://fedoramagazine.org/managing-partitions-with-sgdisk/)
[#]: author: (Gregory Bartholomew https://fedoramagazine.org/author/glb/)
Managing Partitions with sgdisk
======
![][1]
[Roderick W. Smith][2]‘s _sgdisk_ command can be used to manage the partitioning of your hard disk drive from the command line. The basics that you need to get started with it are demonstrated below.
The following six parameters are all that you need to know to make use of sgdisk’s most basic features:
1. **-p**
_Print_ the partition table:
### sgdisk -p /dev/sda
2. **-d x**
_Delete_ partition x:
### sgdisk -d 1 /dev/sda
3. **-n x:y:z**
Create a _new_ partition numbered x, starting at y and ending at z:
### sgdisk -n 1:1MiB:2MiB /dev/sda
4. **-c x:y**
_Change_ the name of partition x to y:
### sgdisk -c 1:grub /dev/sda
5. **-t x:y**
Change the _type_ of partition x to y:
### sgdisk -t 1:ef02 /dev/sda
6. **–list-types**
List the partition type codes:
### sgdisk --list-types
![The SGDisk Command][3]
As you can see in the above examples, most of the commands require that the [device file name][4] of the hard disk drive to operate on be specified as the last parameter.
The parameters shown above can be combined so that you can completely define a partition with a single run of the sgdisk command:
### sgdisk -n 1:1MiB:2MiB -t 1:ef02 -c 1:grub /dev/sda
Relative values can be specified for some fields by prefixing the value with a **+** or **–** symbol. If you use a relative value, sgdisk will do the math for you. For example, the above example could be written as:
### sgdisk -n 1:1MiB:+1MiB -t 1:ef02 -c 1:grub /dev/sda
The value **0** has a special-case meaning for several of the fields:
* In the _partition number_ field, 0 indicates that the next available number should be used (numbering starts at 1).
* In the _starting address_ field, 0 indicates that the start of the largest available block of free space should be used. Some space at the start of the hard drive is always reserved for the partition table itself.
* In the _ending address_ field, 0 indicates that the end of the largest available block of free space should be used.
By using **0** and relative values in the appropriate fields, you can create a series of partitions without having to pre-calculate any absolute values. For example, the following sequence of sgdisk commands would create all the basic partitions that are needed for a typical Linux installation if in run sequence against a blank hard drive:
### sgdisk -n 0:0:+1MiB -t 0:ef02 -c 0:grub /dev/sda
### sgdisk -n 0:0:+1GiB -t 0:ea00 -c 0:boot /dev/sda
### sgdisk -n 0:0:+4GiB -t 0:8200 -c 0:swap /dev/sda
### sgdisk -n 0:0:0 -t 0:8300 -c 0:root /dev/sda
The above example shows how to partition a hard disk for a BIOS-based computer. The [grub partition][5] is not needed on a UEFI-based computer. Because sgdisk is calculating all the absolute values for you in the above example, you can just skip running the first command on a UEFI-based computer and the remaining commands can be run without modification. Likewise, you could skip creating the swap partition and the remaining commands would not need to be modified.
There is also a short-cut for deleting all the partitions from a hard disk with a single command:
### sgdisk --zap-all /dev/sda
For the most up-to-date and detailed information, check the man page:
$ man sgdisk
--------------------------------------------------------------------------------
via: https://fedoramagazine.org/managing-partitions-with-sgdisk/
作者：[Gregory Bartholomew][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/glb/
[b]: https://github.com/lujun9972
[1]: https://fedoramagazine.org/wp-content/uploads/2019/04/managing-partitions-816x345.png
[2]: https://www.rodsbooks.com/
[3]: https://fedoramagazine.org/wp-content/uploads/2019/04/sgdisk.jpg
[4]: https://en.wikipedia.org/wiki/Device_file
[5]: https://en.wikipedia.org/wiki/BIOS_boot_partition

135
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[#]: 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

73
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[#]: 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

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[#]: 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

103
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[#]: 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

57
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[#]: 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/

192
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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

159
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@@ -0,0 +1,159 @@
[#]: 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/)
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。
因为大多数的 Linux 系统使用 UUID 挂载分区。在 `/etc/fstab` 文件中可以验证此的内容。
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 代表着通用唯一识别码，它帮助 Linux 系统去识别一个磁盘驱动分区而不是块设备文件。
libuuid 是内核 2.15.1 中 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，可以合理地认为它在一个系统中是唯一的，并且在所有系统中也是唯一的。
在计算机系统中使用了 128 位数字去标识信息。UUID 最初被用在 Apollo 网络计算机系统（NCS）中，之后 UUID 被开放软件基金会（OSF）标准化，成为分布式计算环境（DCE）的一部分。
UUID 以 32 个十六进制（基数为 16）的数字表示，被连字符分割为 5 组显示，总共的 36 个字符格式为 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：`** lsblk 列出所有可用的或指定的块设备的信息。
* **`hwinfo 命令：`** hwinfo 表示硬件信息工具，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 数据库是不可用的或者编译的 lsblk 是不支持 udev 的，它会试图从块设备中读取 LABEL，UUID 和文件系统类型。这种情况下，必须为 root 身份。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]** 表示硬件信息工具，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 的运行时的行为，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：[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/

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[#]: 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/)
Linux 中如何配置 sudo 访问权限？
======
Linux 系统中 root 用户拥有所有的控制权力。
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` 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 wheel 组下的 sudoers 文件中即可。
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` 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 sudo 或 admin 组下的 sudoers 文件中即可。
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：[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

189
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[#]: 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/

120
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@@ -0,0 +1,120 @@
[#]: collector: (lujun9972)
[#]: translator: (MjSeven)
[#]: reviewer: ( )
[#]: publisher: ( )
[#]: url: ( )
[#]: subject: (5 useful open source log analysis tools)
[#]: via: (https://opensource.com/article/19/4/log-analysis-tools)
[#]: author: (Sam Bocetta https://opensource.com/users/sambocetta)
5 个有用的开源日志分析工具
======
监控网络活动既重要又繁琐，以下这些工具可以使它更容易。
![People work on a computer server][1]
监控网络活动是一项繁琐的工作，但有充分的理由这样做。例如，它允许你查找和调查工作站、连接到网络的设备和服务器上的可疑登录，同时确定管理员滥用了什么。你还可以跟踪软件安装和数据传输，以实时识别潜在问题，而不是在损坏发生后才进行跟踪。
这些日志还有助于使你的公司遵守适用于在欧盟范围内运营的任何实体的[通用数据保护条例][2]（GFPR）。如果你的网站在欧盟可以浏览，那么你就有资格。
日志记录，包括跟踪和分析，应该是任何监控基础设置中的一个基本过程。要从灾难中恢复 SQL Server 数据库，需要事务日志文件。此外，通过跟踪日志文件，DevOps 团队和数据库管理员（DBA）可以保持最佳的数据库性能，或者，在网络攻击的情况下找到未经授权活动的证据。因此，定期监视和分析系统日志非常重要。这是一种可靠的方式来重新创建导致出现任何问题的事件链。
现在有很多开源日志跟踪器和分析工具可供使用，这使得为活动日志选择合适的资源比你想象的更容易。免费和开源软件社区提供的日志设计适用于各种站点和操作系统。以下是五个我用过的最好的，它们并没有特别的顺序。
### Graylog
[Graylog][3] 于 2011 年在德国启动，现在作为开源工具或商业解决方案提供。它被设计成一个集中式日志管理系统，接受来自不同服务器或端点的数据流，并允许你快速浏览或分析该信息。
![Graylog screenshot][4]
Graylog 在系统管理员中建立了良好的声誉，因为它易于扩展。大多数 Web 项目都是从小规模开始的，‘但它们可能指数级增长。Graylog 可以平衡后端服务网络中的负载，每天可以处理几 TB 的日志数据。
IT 管理员会发现 Graylog 的前端界面易于使用，而且功能强大。Graylog 是围绕仪表板的概念构建的，它允许你选择你认为最有价值的指标或数据源，并快速查看一段时间内的趋势。
当发生安全或性能事件时，IT 管理员希望能够尽可能地将症状追根溯源。Graylog 的搜索功能使这变得容易。它有内置的容错功能，可运行多线程搜索，因此你可以同时分析多个潜在的威胁。
### Nagios
[Nagios][5] 于 1999 年开始由一个开发人员开发，现在已经发展成为管理日志数据最可靠的开源工具之一。当前版本的 Nagios 可以与运行 Microsoft Windows, Linux 或 Unix 的服务器集成。
![Nagios Core][6]
它的主要产品是日志服务器，旨在简化数据收集并使系统管理员更容易访问信息。Nagios 日志服务器引擎将实时捕获数据并将其提供给一个强大的搜索工具。通过内置的设置向导，可以轻松地与新端点或应用程序集成。
Nagios 最常用于需要监控其本地网络安全性的组织。它可以审核一系列与网络相关的事件，并帮助自动分发警报。如果满足特定条件，甚至可以将 Nagios 配置为运行预定义的脚本，从而允许你在人员介入之前解决问题。
作为网络审核的一部分，Nagios 将根据日志数据来源的地理位置过滤日志数据。这意味着你可以使用映射技术构建全面的仪表板，以了解 Web 流量是如何流动的。
### Elastic Stack ("ELK Stack")
[Elastic Stack][7]，通常称为 ELK Stack，是需要筛选大量数据并理解其日志系统的组织中最受欢迎的开源工具之一（这也是我个人的最爱）。
![ELK Stack][8]
它的主要产品由三个独立的产品组成：Elasticsearch, Kibana 和 Logstash:
* 顾名思义， _**Elasticsearch**_ 旨在帮助用户使用多种查询语言和类型在数据集中找到匹配项。速度是它最大的优势。它可以扩展成由数百个服务器节点组成的集群，轻松处理 PB 级的数据。
* _**Kibana**_ 是一个可视化工具，与 Elasticsearch 一起工作，允许用户分析他们的数据并构建强大的报告。当你第一次在服务器集群上安装 Kibana 引擎时，你将访问一个显示统计数据、图表甚至是动画的界面。
* ELK Stack 的最后一部分是 _**Logstash**_ ，它作为一个纯粹的服务端管道进入 Elasticsearch 数据库。你可以将 Logstash 与各种编程语言和 API 集成，这样你的网站和移动应用程序中的信息就可以直接提供给强大的 Elastic Stalk 搜索引擎中。
ELK Stack 的一个独特功能是，它允许你监视构建在 WordPress 开源安装上的应用程序。与[跟踪管理员和 PHP 日志][9]的大多数开箱即用的安全审计日志工具相比，ELK Stack 可以筛选 Web 服务器和数据库日志。
糟糕的日志跟踪和数据库管理是导致网站性能不佳的最常见原因之一。没有定期检查、优化和清空数据库日志，不仅会降低站点的运行速度，还可能导致其完全崩溃。因此，ELK Stack 对于每个 WordPress 开发人员的工具包来说都是一个优秀的工具。
### LOGalyze
[LOGalyze][11] 是一个位于匈牙利的组织，它为系统管理员和安全专家构建开源工具，以帮助他们管理服务器日志，并将其转换为有用的数据点。其主要产品可供个人或商业用户免费下载。
![LOGalyze][12]
LOGalyze 被设计成一个巨大的管道，其中多个服务器、应用程序和网络设备可以使用简单对象访问协议（SOAP）方法提供信息。它提供了一个前端界面，管理员可以登录界面来监控数据集并开始分析数据。
在 LOGalyze 的 Web 界面中，你可以运行动态报告，并将其导出到 Excel 文件、PDF 文件或其他格式。这些报告可以基于 LOGalyze 后端管理的多维统计信息。它甚至可以跨服务器或应用程序组合数据字段，借此来帮助你发现性能趋势。
LOGalyze 旨在不到一个小时内完成安装和配置。它具有预先构建的功能，允许它以法律所要求的格式收集审计数据。例如，LOGalyze 可以很容易地运行不同的 HIPAA 报告，以确保你的组织遵守健康法律并保持合规性。
### Fluentd
如果你所在组织的数据源位于许多不同的位置和环境中，那么你的目标应该是尽可能地将它们集中在一起。否则，你将难以监控性能并防范安全威胁。
[Fluentd][13] 是一个强大的数据收集解决方案，它是完全开源的。它没有提供完整的前端界面，而是作为一个收集层来帮助组织不同的管道。Fluentd 在被世界上一些最大的公司使用，但是也可以在较小的组织中实施。
![Fluentd architecture][14]
Fluentd 最大的好处是它与当今最常用的技术工具兼容。例如，你可以使用 Fluentd 从 Web 服务器（如 Apache）、智能设备传感器和 MongoDB 的动态记录中收集数据。如何处理这些数据完全取决于你。
Fluentd 基于 JSON 数据格式，它可以与由卓越的开发人员创建的 [500 多个插件][15]一起使用。这使你可以将日志数据扩展到其他应用程序中，并通过最少的手工操作从中获得更好的分析。
### 写在最后
如果出于安全原因、政府合规性和衡量生产力的原因，你还没有使用活动日志，那么现在开始改变吧。市场上有很多插件，它们可以与多种环境或平台一起工作，甚至可以在内部网络上使用。不要等发生了严重的事件，才采取一个积极主动的方法去维护和监督日志。
--------------------------------------------------------------------------------
via: https://opensource.com/article/19/4/log-analysis-tools
作者：[Sam Bocetta][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/sambocetta
[b]: https://github.com/lujun9972
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/rh_003499_01_linux11x_cc.png?itok=XMDOouJR (People work on a computer server)
[2]: https://opensource.com/article/18/4/gdpr-impact
[3]: https://www.graylog.org/products/open-source
[4]: https://opensource.com/sites/default/files/uploads/graylog-data.png (Graylog screenshot)
[5]: https://www.nagios.org/downloads/
[6]: https://opensource.com/sites/default/files/uploads/nagios_core_4.0.8.png (Nagios Core)
[7]: https://www.elastic.co/products
[8]: https://opensource.com/sites/default/files/uploads/elk-stack.png (ELK Stack)
[9]: https://www.wpsecurityauditlog.com/benefits-wordpress-activity-log/
[10]: https://websitesetup.org/how-to-speed-up-wordpress/
[11]: http://www.logalyze.com/
[12]: https://opensource.com/sites/default/files/uploads/logalyze.jpg (LOGalyze)
[13]: https://www.fluentd.org/
[14]: https://opensource.com/sites/default/files/uploads/fluentd-architecture.png (Fluentd architecture)
[15]: https://opensource.com/article/18/9/open-source-log-aggregation-tools

86
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[#]: 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)
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
![编程中的女士][1]
最近在线新闻通讯社对 [Google 的 Chromecast 音频设备的推出][2]发出哀叹。该设备在音频媒体界受到[好评][3]，因此我已经在考虑入手一个。基于 Chromecast 毁灭的消息，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。它被包在一个常用但是最简的 Google 包装袋中，外面打印着非常简短的开始指南。
![Google Chromecast 音频][5]
我用光缆把它通过我的数模转换器的光学 S/PDIF 连接接入家庭音响，希望以此能提供最佳的音质。
安装过程并无纰漏，在五分钟后我就准备好播放一些音乐了。我知道一些安卓应用支持 Chromecast，因此我决定用 Google Play 音乐测试它。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 Android application][6] 满足条件。它开源并且可从 [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]
安装过程快速平滑，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。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。
我决定找一些我最爱的网络广播电台，在法国马赛的 [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，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 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；为 WAV 和 FLAC 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——电音但又不（总体来说）是舞蹈，他们的音乐旋律优美，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；大量与音乐家的合作；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：[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

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[#]: collector: (lujun9972)
[#]: translator: (MjSeven)
[#]: 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: 该使用哪种语言？
======
两种编程语言都各有优缺点，一些任务使得它们在某些方面互有胜负。
![][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。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（最多 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，但执行时间性能差
* Windows 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。
* 管道 ("|") CLI 实用程序如 sed、awk、grep 等可以降低其性能
* 缺少很多函数、对象、数据结构和多线程，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，默认情况下它安装在大多数 Unix/Linux 系统中
* 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很多行代码的复杂软件应用程序中是一种很棒的语言
* 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：[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

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@@ -1,5 +1,5 @@
[#]: collector: (lujun9972)
[#]: translator: ( )
[#]: translator: (MjSeven)
[#]: reviewer: ( )
[#]: publisher: ( )
[#]: url: ( )
@@ -7,69 +7,68 @@
[#]: via: (https://www.2daygeek.com/how-to-install-and-enable-flatpak-support-on-linux/)
[#]: author: (Magesh Maruthamuthu https://www.2daygeek.com/author/magesh/)
How To Install And Enable Flatpak Support On Linux?
如何在 Linux 上安装并启用 Flatpak 支持？
======
Currently we all are using distributions official package managers to install any required packages.
<to 校正：之前似乎发表过跟这个类似的一篇 https://linux.cn/article-10459-1.html>
in Linux, it’s doing good without any issues. (It’s doing their job nicely without any compromise)
目前，我们都在使用 Linux 发行版的官方软件包管理器来安装所需的软件包。
There was some limitation on this that will think about other alternative solutions to fix it.
在 Linux 中，它做得很好，没有任何问题。（它很好地完成了它应该做的工作，同时它没有任何妥协）
Yes, by default we won’t get the latest version of packages from the distributions official package managers because as these were built while building a current OS version. And they offers only security updates until the next major release comes.
在一些方面它也有一些限制，所以会让我们考虑其他替代解决方案来解决。
So, what will be the solution for this?
是的，默认情况下，我们不会从发行版官方软件包管理器获取最新版本的软件包，因为这些软件包是在构建当前 OS 版本时构建的。它们只会提供安全更新，直到下一个主要版本发布。
Yes, we have multiple solutions for this and most of us were already started using few of those.
那么，这种情况有什么解决办法吗？
What it is and what is the benefit of those?
是的，我们有多种解决方案，而且我们大多数人已经开始使用其中的一些了。
* **For Ubuntu based systems:** PPAs
* **For RHEL based systems:** [EPEL Repository][1], [ELRepo Repository][2], [nux-dextop Repository][3], [IUS Community Repo][4], [RPMfusion Repository][5] and [Remi Repository][6].
有些什么呢，它们有什么好处？
* **对于基于 Ubuntu 的系统：** PPAs
* **对于基于 RHEL 的系统：** [EPEL Repository][1]、[ELRepo Repository][2]、[nux-dextop Repository][3]、[IUS Community Repo][4]、[RPMfusion Repository][5] 和 [Remi Repository][6]
使用上面的仓库，我们将获得最新的软件包。这些软件包通常都得到了很好的维护，还有大多数社区的建议。但这对于操作系统来说应该是适当的，因为它们可能并不安全。
Using the above repos, we will be getting the latest packages for the distribution. And these are usually well maintained and suggested by most of the community. But these are advisable by the OS and may not always be safe.
近年来，出现了一下通用软件包封装格式，并且得到了广泛的应用。
In recent years, the following universal packaging formats were come out and gained a lot of popularity.
* **`Flatpak:`** 它是独立于发行版的包格式，主要贡献者是 Fedora 项目团队。大多数主要的 Linux 发行版都采用了 Flatpak 框架。
* **`Snaps:`** Snappy 是一种通用的软件包封装格式，最初由 Canonical 为 Ubuntu 手机及其操作系统设计和构建的。后来，大多数发行版都进行了改编。
* **`AppImage:`** AppImage 是一种可移植的包格式，可以在不安装或不需要 root 权限的情况下运行。
* **`Flatpak:`**`` It’s distribution independent package format and the main contributor is Fedora project team. The Flatpak framework is adopted by most of the major Linux distributions.
* **`Snaps:`**`` Snappy is a universal packaging formats originally designed and built by Canonical for the Ubuntu phone and it’s operating system. Later most of the distributions are adapted.
* **`AppImage:`**`` AppImage is a portable package format and it can run without installation or the need for root rights.
我们之前已经介绍过 **[Snap 包管理器和包封装格式][7]**。今天我们将讨论 Flatpak 包封装格式。
### 什么是 Flatpak？
Flatpak（以前称为 X Desktop Group 或 xdg-app）是一个软件实用程序。它提供了一种通用的包封装格式，可以在任何 Linux 发行版中使用。
We had already covered about the **[Snap package manager& packaging format][7]** in the past. Today we are going to discuss about Flatpak packing format.
它提供了一个沙箱（隔离的）环境来运行应用程序，不会影响其他应用程序和发行版核心软件包。我们还可以安装并运行不同版本的软件包。
### What Is Flatpak?
Flatpak 的一个缺点是不像 Snap 和 AppImage 那样支持服务器操作系统，它只在少数桌面环境下工作。
Flatpak (formerly know as X Desktop Group or xdg-app) is a software utility. It’s offering a universal packaging formats which can be used in any Linux distributions.
比如说，如果你想在系统上运行两个版本的 php，那么你可以轻松安装并按照你的意愿运行。
It provides a sandbox (isolated) environment to run the app and it doesn’t impact either other apps and distribution core packages. Also we can install and run the different version of same package.
这就是现在通用包封装格式非常有名的地方。
There is an disadvantage on flatpak is that doesn’t support server OS unlike Snap and AppImage. It’s working only on few desktops environment.
### 如何在 Linux 中安装 Flatpak？
Say for example. If you would like to run two version of php on your system then you can easily install and run as your wish.
大多数 Linux 发行版官方仓库都提供 Flatpak 软件包。因此，可以使用它们来进行安装。
That’s where the universal packaging formats are become very famous nowadays.
### How To Install Flatpak On Linux?
Flatpak package is available in most of the Linux distribution official repository. Hence, it can be installed using those.
For **`Fedora`** system, use **[DNF Command][8]** to install flatpak.
对于 **`Fedora`** 系统，使用 **[DNF 命令][8]** 来安装 flatpak。
```
$ sudo dnf install flatpak
```
For **`Debian/Ubuntu`** systems, use **[APT-GET Command][9]** or **[APT Command][10]** to install flatpak.
对于 **`Debian/Ubuntu`** 系统，使用 **[APT-GET 命令][9]** 或 **[APT 命令][10]** 来安装 flatpak。
```
$ sudo apt install flatpak
```
For older Ubuntu versions.
对于较旧的 Ubuntu 版本：
```
$ sudo add-apt-repository ppa:alexlarsson/flatpak
@@ -77,52 +76,52 @@ $ sudo apt update
$ sudo apt install flatpak
```
For **`Arch Linux`** based systems, use **[Pacman Command][11]** to install flatpak.
对于基于 **`Arch Linux`** 的系统，使用 **[Pacman 命令][11]** 来安装 flatpak。
```
$ sudo pacman -S flatpak
```
For **`RHEL/CentOS`** systems, use **[YUM Command][12]** to install flatpak.
对于 **`RHEL/CentOS`** 系统，使用 **[YUM 命令][12]** 来安装 flatpak。
```
$ sudo yum install flatpak
```
For **`openSUSE Leap`** system, use **[Zypper Command][13]** to install flatpak.
对于 **`openSUSE Leap`** 系统，使用 **[Zypper 命令][13]** 来安装 flatpak。
```
$ sudo zypper install flatpak
```
### How To Enable Flathub Support On Linux?
### 如何在 Linux 上启用 Flathub 支持？
Flatbub website is a app store for Flatpak packages where you can find them.
Flathub 网站是一个应用程序商店，你可以在其中找到 flatpak。
It’s a central repository where all the flatpak applications are available for users.
它是一个中央仓库，所有的 flatpak 应用程序都可供用户使用。
Run the following command to enable Flathub support on Linux.
运行以下命令在 Linux 上启用 Flathub 支持：
```
$ sudo flatpak remote-add --if-not-exists flathub https://flathub.org/repo/flathub.flatpakrepo
```
Install the Software Flatpak plugin for GNOME Desktop Environment.
为 GNOME 桌面环境安装 Software Flatpak 插件。
```
$ sudo apt install gnome-software-plugin-flatpak
```
Also, you can enable GNOME Repository if you are using GNOME Desktop Environment. It’s containing all GNOME core applications.
此外，如果你使用的是 GNOME 桌面环境，则可以启用 GNOME 仓库。它包含所有 GNOME 核心应用程序。
```
$ wget https://sdk.gnome.org/keys/gnome-sdk.gpg
$ sudo flatpak remote-add --gpg-import=gnome-sdk.gpg --if-not-exists gnome-apps https://sdk.gnome.org/repo-apps/
```
### How To List configured flatpak repositories?
### 如何列出已配置的 flakpak 仓库？
Run the following command, if you would like to view list of the configured flatpak repositories on your system.
如果要查看系统上已配置的 flatpak 仓库列表，运行以下命令：
```
$ flatpak remotes
@@ -131,9 +130,9 @@ flathub system
gnome-apps system
```
### How To List The Available Packages In The Configured Repositories?
### 如何列出已配置仓库中的可用软件包？
Run the following command, if you would like to view list of the available packages (It will display all together like, applications and run times) in the configured repositories.
如果要查看已配置仓库中的可用软件包的列表（它将显示所有软件包，如应用程序和运行环境），运行以下命令：
```
$ flatpak remote-ls | head -10
@@ -150,21 +149,21 @@ org.gnome.Documents gnome-apps
org.gnome.Epiphany gnome-apps
```
To list only applications not runtimes.
仅列出应用程序：
```
$ flatpak remote-ls --app
```
To list specific repository applications.
列出特定的仓库应用程序：
```
$ flatpak remote-ls gnome-apps
```
### How To Install A Package From flatpak?
### 如何从 flatpak 安装包？
Run the following command to install a package from flatpak repository.
运行以下命令从 flatpak 仓库安装软件包：
```
$ sudo flatpak install flathub com.github.muriloventuroso.easyssh
@@ -198,24 +197,24 @@ Installing: com.github.muriloventuroso.easyssh.Locale/x86_64/stable from flathub
Now at af837356b222.
```
All the installed application will be placed in the following location.
所有已安装的应用程序都将放在以下位置：
```
$ ls /var/lib/flatpak/app/
com.github.muriloventuroso.easyssh
```
### How To Run The Installed Application?
### 如何运行已安装的应用程序？
Run the following command to launch the required application. Make sure, you have to replace with your application name instead.
运行以下命令以启动所需的应用程序，确保替换为你的应用程序名称：
```
$ flatpak run com.github.muriloventuroso.easyssh
```
### How To View The Installed Application?
### 如何查看已安装的应用程序？
Run the following command to view the installed application.
运行以下命令来查看已安装的应用程序：
```
$ flatpak list
@@ -225,9 +224,9 @@ org.freedesktop.Platform.html5-codecs/x86_64/18.08 system,runtime
org.gnome.Platform/x86_64/3.30 system,runtime
```
### How To View The Detailed Information About The Installed Application?
### 如何查看有关已安装应用程序的详细信息？
Run the following command to view the detailed information about the installed application.
运行以下命令以查看有关已安装应用程序的详细信息。
```
$ flatpak info com.github.muriloventuroso.easyssh
@@ -248,29 +247,28 @@ Runtime: org.gnome.Platform/x86_64/3.30
Sdk: org.gnome.Sdk/x86_64/3.30
```
### How To Update The Installed Application?
### 如何更新已安装的应用程序？
Run the following command to updated the installed application to latest version.
运行以下命令将已安装的应用程序更新到最新版本：
```
$ flatpak update
```
For specific application, use the following format.
对于特定应用程序，使用以下格式：
```
$ flatpak update com.github.muriloventuroso.easyssh
```
### How To Remove The Installed Application?
Run the following command to remove the installed application.
### 如何移除已安装的应用程序？
运行以下命令来移除已安装的应用程序：
```
$ sudo flatpak uninstall com.github.muriloventuroso.easyssh
```
Go to the man page for more details and options.
进入 man 页面以获取更多细节和选项：
```
$ flatpak --help
@@ -282,7 +280,7 @@ via: https://www.2daygeek.com/how-to-install-and-enable-flatpak-support-on-linux
作者：[Magesh Maruthamuthu][a]
选题：[lujun9972][b]
译者：[译者ID](https://github.com/译者ID)
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

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[#]: collector: (lujun9972)
[#]: translator: (heguangzhi)
[#]: reviewer: ( )
[#]: publisher: ( )
[#]: url: ( )
[#]: 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。
这些文章内容帮助您如何检查远程服务器中给定的端口是否打开。
如果您想 **[检查远程 Linux 系统上的端口是否打开][1]** 请点击链接浏览。
如果您想 **[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。
如果您想 **[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。
但是本文帮助您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。
您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,多点传送成员和网络端口。
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
```
您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。它也可以类似 netstat 使用。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 :::*
```
您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(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
```
您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？
它向您显示系统上打开的文件列表以及打开它们的进程。还会向您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)
```
您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：[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/
[2]: https://www.2daygeek.com/check-a-open-port-on-multiple-remote-linux-server-using-nc-command/