diff --git a/published/20120104 Computer Laboratory - Raspberry Pi- Lesson 0 Introduction.md b/published/20120104 Computer Laboratory - Raspberry Pi- Lesson 0 Introduction.md index a9442dc04c..7feabfede3 100644 --- a/published/20120104 Computer Laboratory - Raspberry Pi- Lesson 0 Introduction.md +++ b/published/20120104 Computer Laboratory - Raspberry Pi- Lesson 0 Introduction.md @@ -14,7 +14,7 @@ ### 1、操作系统 -操作系统就是一个非常复杂的程序。它的任务就是组织安排计算机上的其它程序，包括共享计算机的时间、内存、硬件和其它资源。你可能听说过的一些比较大的桌面操作系统家族有 GNU/Linux、Mac OS X 和 Microsoft Windows。其它的设备比如电话，也需要操作系统，它可能使用的操作系统是 Android、iOS 和 [Windows Phone](https://www.cl.cam.ac.uk/projects/raspberrypi/tutorials/os/introduction.html#note1)。 +操作系统就是一个非常复杂的程序。它的任务就是组织安排计算机上的其它程序，包括共享计算机的时间、内存、硬件和其它资源。你可能听说过的一些比较大的桌面操作系统家族有 GNU/Linux、Mac OS X 和 Microsoft Windows。其它的设备比如电话，也需要操作系统，它可能使用的操作系统是 Android、iOS 和 Windows Phone。 [^1] 由于操作系统是用来与计算机系统上的硬件进行交互的，所以它必须了解系统上硬件专有的信息。为了能让操作系统适用于各种类型的计算机，发明了 **驱动程序** 的概念。驱动程序是为了能够让操作系统与特定的硬件进行交互而添加（并可删除）到操作系统上的一小部分代码。在本课程中，我们并不涉及如何创建可删除的驱动程序，而是专注于特定的一个硬件：树莓派。 @@ -26,7 +26,7 @@ 本课程几乎要完全靠汇编代码来写。汇编代码非常接近计算机的底层。计算机其实是靠一个叫处理器的设备来工作的，处理器能够执行像加法这样的简单任务，还有一组叫做 RAM 的芯片，它能够用来保存数字。当计算机通电后，处理器执行程序员给定的一系列指令，这将导致内存中的数字发生变化，以及与连接的硬件进行交互。汇编代码只是将这些机器命令转换为人类可读的文本。 -常规的编程就是，程序员使用编程语言，比如 C++、Java、C#、Basic 等等来写代码，然后一个叫编译器的程序将程序员写的代码转换成汇编代码，然后进一步转换为[二进制代码](https://www.cl.cam.ac.uk/projects/raspberrypi/tutorials/os/introduction.html#note2)。二进制代码才是计算机真正能够理解的东西，但它是人类无法读取的东西。汇编代码比二进制代码好一点，至少它的命令是人类可读的，但它仍然让人很沮丧。请记住，你用汇编代码写的每个命令都是处理器可以直接认识的，因此这些命令设计的很简单，因为物理电路必须能够处理每个命令。 +常规的编程就是，程序员使用编程语言，比如 C++、Java、C#、Basic 等等来写代码，然后一个叫编译器的程序将程序员写的代码转换成汇编代码，然后进一步转换为二进制代码。[^2] 二进制代码才是计算机真正能够理解的东西，但它是人类无法读取的东西。汇编代码比二进制代码好一点，至少它的命令是人类可读的，但它仍然让人很沮丧。请记住，你用汇编代码写的每个命令都是处理器可以直接认识的，因此这些命令设计的很简单，因为物理电路必须能够处理每个命令。 ![Compiler process][1] @@ -34,6 +34,9 @@ 现在，你已经准备好进入第一节课了，它是 [课程 1 OK01][2] +[^1]: 要查看更完整的操作系统列表，请参照：[操作系统列表 - Wikipedia](http://en.wikipedia.org/wiki/List_of_operating_systems) +[^2]: 当然，我简化了普通编程的这种解释，实际上它在很大程度上取决于语言和机器。感兴趣的话，参见 [编译器 - Wikipedia](http://en.wikipedia.org/wiki/Compiler) + -------------------------------------------------------------------------------- via: https://www.cl.cam.ac.uk/projects/raspberrypi/tutorials/os/introduction.html diff --git a/published/20170921 The Rise and Rise of JSON.md b/published/20170921 The Rise and Rise of JSON.md new file mode 100644 index 0000000000..ffc62b5afe --- /dev/null +++ b/published/20170921 The Rise and Rise of JSON.md @@ -0,0 +1,115 @@ +[#]: collector: (lujun9972) +[#]: translator: (runningwater) +[#]: reviewer: (wxy) +[#]: publisher: (wxy) +[#]: subject: (The Rise and Rise of JSON) +[#]: via: (https://twobithistory.org/2017/09/21/the-rise-and-rise-of-json.html) +[#]: author: (https://twobithistory.org) +[#]: url: (https://linux.cn/article-10440-1.html) + +JSON 的兴起与崛起 +====== + +JSON 已经占领了全世界。当今，任何两个应用程序彼此通过互联网通信时，可以打赌它们在使用 JSON。它已被所有大型企业所采用：十大最受欢迎的 web API 接口列表中（主要由 Google、Facebook 和 Twitter 提供），仅仅只有一个 API 接口是以 XML 的格式开放数据的。[^1] 这个列表中的 Twitter API 为此做了一个鲜活的注脚：其对 XML 格式的支持到 2013 年结束，其时发布的新版本的 API 取消 XML 格式，转而仅使用 JSON。JSON 也在程序编码级别和文件存储上被广泛采用：在 Stack Overflow（LCTT 译注：一个面向程序员的问答网站）上，现在更多的是关于 JSON 的问题，而不是其他的数据交换格式。[^2] + +![][1] + +XML 仍然在很多地方存在。网络上它被用于 SVG 和 RSS / Atom 信息流。Android 开发者想要获得用户权限许可时，需要在其 APP 的 `manifest` 文件中声明 —— 此文件是 XML 格式的。XML 的替代品也不仅仅只有 JSON，现在有很多人在使用 YAML 或 Google 的 Protocol Buffers 等技术，但这些技术的受欢迎程度远不如 JSON。目前来看，JSON 是应用程序在网络之间通信的首选协议格式。 +考虑到自 2005 年来 Web 编程世界就垂涎于 “异步 JavaScript 和 XML” 而非 “异步 JavaScript 和 JSON” 的技术潜力，你可以发现 JSON 的主导地位是如此的让人惊讶。当然了，这可能与这两种通信格式的受欢迎程度无关，而仅反映出缩写 “AJAX” 似乎比 “AJAJ” 更具吸引力。但是，即使在 2005 年有些人（实际上没有太多人）已经用 JSON 来取代 XML 了，我们不禁要问为什么 XML 的噩运来的如此之快，以至于短短十来年，“异步 JavaScript 和 XML” 这个名称就成为一个很讽刺的误称。那这十来年发生了什么？JSON 怎么会在那么多应用程序中取代了 XML？现在被全世界工程师和系统所使用、依赖的这种数据格式是谁提出的？ + +### JSON 之诞生 + +2001 年 4 月，首个 JSON 格式的消息被发送出来。此消息是从旧金山湾区某车库的一台计算机发出的，这是计算机历史上重要的的时刻。Douglas Crockford 和 Chip Morningstar 是一家名为 State Software 的技术咨询公司的联合创始人，他们当时聚集在 Morningstar 的车库里测试某个想法，发出了此消息。 + +在 “AJAX” 这个术语被创造之前，Crockford 和 Morningstar 就已经在尝试构建好用的 AJAX 应用程序了，可是浏览器对其兼容性不好。他们想要在初始页面加载后就将数据传递给应用程序，但其目标要针对所有的浏览器，这就实现不了。 + +这在今天看来不太可信，但是要记得 2001 年的时候 Internet Explorer（IE）代表了网页浏览器的最前沿技术产品。早在 1999 年的时候，Internet Explorer 5 就支持了原始形式的 `XMLHttpRequest`，开发者可以使用名为 ActiveX 的框架来访问此对象。Crockford 和 Morningstar 能够使用此技术（在 IE 中）来获取数据，但是在 Netscape 4 中（这是他们想要支持的另一种浏览器）就无法使用这种解决方案。为此 Crockford 和 Morningstar 只得使用一套不同的系统以兼容不同的浏览器。 + +第一条 JSON 消息如下所示： + +``` + +``` + +消息中只有一小部分类似于今天我们所知的 JSON，本身其实是一个包含有一些 JavaScript 的 HTML 文档。类似于 JSON 的部分只是传递给名为 `receive()` 的函数的 JavaScript 对象字面量。 + +Crockford 和 Morningstar 决定滥用 HTML 的帧（``）以发送数据。他们可以让一个帧指向一个返回的上述 HTML 文档的 URL。当接收到 HTML 时，JavaScript 代码段就会运行，就可以把数据对象字面量如实地传递回应用程序。只要小心的回避浏览器保护策略（即子窗口不允许访问父窗口），这种技术就可以正常运行无误。可以看到 Crockford 和 Mornginstar 通过明确地设置文档域这种方法来达到其目的。（这种基于帧的技术，有时称为隐藏帧技术，通常在 90 年代后期，即在广泛使用 XMLHttpRequest 技术之前使用。[^3] ） + +第一个 JSON 消息的惊人之处在于，它显然不是一种新的数据格式的首次使用。它就是 JavaScript！实际上，以此方式使用 JavaScript 的想法如此简单，Crockford 自己也说过他不是第一个这样做的人。他说 Netscape 公司的某人早在 1996 年就使用 JavaScript 数组字面量来交换信息。[^4] 因为消息就是 JavaScript，其不需要任何特殊解析工作，JavaScript 解释器就可搞定一切。 + +最初的 JSON 信息实际上与 JavaScript 解释器发生了冲突。JavaScript 保留了大量的关键字（ECMAScript 6 版本就有 64 个保留字），Crockford 和 Morningstar 无意中在其 JSON 中使用了一个保留字。他们使用了 `do` 作为了键名，但 `do` 是解释器中的保留字。因为 JavaScript 使用的保留字太多了，Crockford 做了决定：既然不可避免的要使用到这些保留字，那就要求所有的 JSON 键名都加上引号。被引起来的键名会被 JavaScript 解释器识别成字符串，其意味着那些保留字也可以放心安全的使用。这就为什么今天 JSON 键名都要用引号引起来的原因。 + +Crockford 和 Morningstar 意识到这技术可以应用于各类应用系统。想给其命名为 “JSML”，即 JavaScript 标记语言JavaScript Markup Language的意思，但发现这个缩写已经被一个名为 Java Speech 标记语言的东西所使用了。因此他们决定采用 “JavaScript Object Notation”，缩写为 JSON。他们开始向客户推销，但很快发现客户不愿意冒险使用缺乏官方规范的未知技术。所以 Crockford 决定写一个规范。 + +2002 年，Crockford 买下了 [JSON.org][2] 域名，放上了 JSON 语法及一个解释器的实例例子。该网站仍然在运行，现在已经包含有 2013 年正式批准的 JSON ECMA 标准的显著链接。在该网站建立后，Crockford 并没有过多的推广，但很快发现很多人都在提交各种不同编程语言的 JSON 解析器实现。JSON 的血统显然与 JavaScript 相关联，但很明显 JSON 非常适合于不同语言之间的数据交换。 + +### AJAX 导致的误会 + +2005 年，JSON 有了一次大爆发。那一年，一位名叫 Jesse James Garrett 的网页设计师和开发者在博客文章中创造了 “AJAX” 一词。他很谨慎地强调：AJAX 并不是新技术，而是 “好几种蓬勃发展的技术以某种强大的新方式汇集在一起。[^5] ” AJAX 是 Garrett 给这种正受到青睐的 Web 应用程序的新开发方法的命名。他的博客文章接着描述了开发人员如何利用 JavaScript 和 XMLHttpRequest 构建新型应用程序，这些应用程序比传统的网页更具响应性和状态性。他还以 Gmail 和 Flickr 网站已经使用 AJAX 技术作为了例子。 + +当然了，“AJAX” 中的 “X” 代表 XML。但在随后的问答帖子中，Garrett 指出，JSON 可以完全替代 XML。他写道：“虽然 XML 是 AJAX 客户端进行数据输入、输出的最完善的技术，但要实现同样的效果，也可以使用像 JavaScript Object Notation（JSON）或任何类似的结构数据方法等技术。 ”[^6] + +开发者确实发现在构建 AJAX 应用程序时可以很容易的使用 JSON，许多人更喜欢它而不是 XML。具有讽刺意味的是，对 AJAX 的兴趣逐渐的导致了 JSON 的普及。大约在这个时候，JSON 引起了博客圈的注意。 + +2006 年，Dave Winer，一位高产的博主，他也是许多基于 XML 的技术（如 RSS 和 XML-RPC）背后的开发工程师，他抱怨到 JSON 毫无疑问的正在重新发明 XML。尽管人们认为数据交换格式之间的竞争不会导致某一技术的消亡。其写到： + +> 毫无疑问，我可以编写一个例程来解析 JSON，但来看看他们要重新发明一个东西有多大的意义，出于某种原因 XML 本身对他们来说还不够好（我很想听听原因）。谁想干这荒谬之事？查找一棵树然后把节点串起来。可以立马试试。[^7] + +我很理解 Winer 的挫败感。事实上并没有太多人喜欢 XML。甚至 Winer 也说过他不喜欢 XML。[^8] 但 XML 已被设计成一个可供任何人使用，并且可以用于几乎能想象到的所有事情。归根到底，XML 实际上是一门元语言，允许你为特定应用程序自定义该领域特定的语言。如 Web 信息流技术 RSS 和 SOAP（简单对象访问协议）就是例子。Winer 认为由于通用交换格式所带来的好处，努力达成共识非常重要。XML 的灵活性应该能满足任何人的需求，然而 JSON 格式呢，其并没有比 XML 提供更多东西，除了它抛弃了使 XML 更灵活的那些繁琐的东西。 + +Crockford 阅读了 Winer 的这篇文章并留下了评论。为了回应 JSON 重新发明 XML 的指责，Crockford 写到：“重造轮子的好处是可以得到一个更好的轮子。”[^9] + +### JSON 与 XML 对比 + +到 2014 年，JSON 已经由 ECMA 标准和 RFC 官方正式认可。它有了自己的 MIME 类型。JSON 已经进入了大联盟时代。 + +为什么 JSON 比 XML 更受欢迎？ + +在 [JSON.org][2] 网站上，Crockford 总结了一些 JSON 的优势。他写到，JSON 的语法极少，其结构可预测，因此 JSON 更容易被人类和机器理解。[^10] 其他博主一直关注 XML 的冗长啰嗦及“尖括号负担”。[^11] XML 中每个开始标记都必须与结束标记匹配，这意味着 XML 文档包含大量的冗余信息。在未压缩时，XML 文档的体积比同等信息量 JSON 文档的体积大很多，但是，更重要的，这也使 XML 文档更难以阅读。 + +Crockford 还声称 JSON 的另一个巨大优势是其被设计为数据交换格式。[^12] 从一开始，它的目的就是在应用程序间传递结构化信息的。而 XML 呢，虽然也可以使用来传递数据，但其最初被设计为文档标记语言。它演变自 SGML（通用标准标记语言），而它又是从被称为 Scribe 的标记语言演变而来，其旨在发展成类似于 LaTeX 一样的文字处理系统。XML 中，一个标签可以包含有所谓的“混合内容”，即带有围绕单词、短语的内嵌标签的文本。这会让人浮现出一副用红蓝笔记录的手稿画面，这是标记语言核心思想的形象比喻。另一方面，JSON 不支持对混合内容模型的清晰构建，但这也意味着它的结构足够简单。一份文档最好的建模就是一棵树，但 JSON 抛弃了这种文档的思想，Crockford 将 JSON 抽象限制为字典和数组，这是所有程序员构建程序时都会使用的最基本的、也最熟悉的元素。 + +最后，我认为人们不喜欢 XML 是因为它让人困惑。它让人迷惑的地方就是有很多不同的风格。乍一看，XML 本身及其子语言（如 RSS、ATOM、SOAP 或 SVG）之间的界限并不明显。典型的 XML 文档的第一行标识了该 XML 的版本，然后该 XML 文档应该符合特定的子语言。这就有变化需要考虑了，特别是跟 JSON 做比较，JSON 是如此简单，以至于永远不需要编写新版本的 JSON 规范。XML 的设计者试图将 XML 做为唯一的数据交换格式以支配所有格式，就会掉入那个经典的程序员陷阱：过度工程化。XML 非常笼统及概念化，所以很难于简单的使用。 + +在 2000 年的时候，发起了一场使 HTML 符合 XML 标准的活动，发布了一份符合 XML 标准的 HTML 开发规范，这就此后很出名的 XHTML。虽然一些浏览器厂商立即开始支持这个新标准，但也很明显，大部分基于 HTML 技术的开发者不愿意改变他们的习惯。新标准要求对 XHTML 文档进行严格的验证，而不是基于 HTML 的基准。但大多的网站都是依赖于 HTML 的宽容规则的。到 2009 年的时候，试图编写第二版本的 XHTML 标准的努力已经流产，因为未来已清晰可见，HTML 将会发展为 HTML5（一种不强制要求接受 XML 规则的标准）。 + +如果 XHTML 的努力取得了成功，那么 XML 可能会成为其设计者所希望的通用数据格式。想象一下，一个 HTML 文档和 API 响应具有完全相同结构的世界。在这样的世界中，JSON 可能不会像现在一样普遍存在。但我把 HTML 的失败看做是 XML 阵营的一种道义上的失败。如果 XML 不是 HTML 的最佳工具，那么对于其他应用程序，也许会有更好的工具出现。在这个世界，我们的世界，很容易看到像 JSON 格式这样的足够简单、量体裁衣的才能获得更大的成功。 + +如果你喜欢这博文，每两周会更新一次！ 请在 Twitter 上关注 [@TwoBitHistory][3] 或订阅 [RSS feed][4]，以确保得到更新的通知。 + +[^1]: http://www.cs.tufts.edu/comp/150IDS/final_papers/tstras01.1/FinalReport/FinalReport.html#software +[^2]: https://insights.stackoverflow.com/trends?tags=json%2Cxml%2Cprotocol-buffers%2Cyaml%2Ccsv +[^3]: Zakas, Nicholas C., et al. “What Is Ajax?” Professional Ajax, 2nd ed., Wiley, 2007. +[^4]: https://youtu.be/-C-JoyNuQJs?t=32s +[^5]: http://adaptivepath.org/ideas/ajax-new-approach-web-applications/ +[^6]: 同上 +[^7]: http://scripting.com/2006/12/20.html +[^8]: http://blogoscoped.com/archive/2009-03-05-n15.html +[^9]: https://scripting.wordpress.com/2006/12/20/scripting-news-for-12202006/#comment-26383 +[^10]: http://www.json.org/xml.html +[^11]: https://blog.codinghorror.com/xml-the-angle-bracket-tax +[^12]: https://youtu.be/-C-JoyNuQJs?t=33m50sgg + +-------------------------------------------------------------------------------- + +via: https://twobithistory.org/2017/09/21/the-rise-and-rise-of-json.html + +作者：[Two-Bit History][a] +选题：[lujun9972][b] +译者：[runningwater](https://github.com/runningwater) +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://twobithistory.org +[b]: https://github.com/lujun9972 +[1]: https://twobithistory.org/images/json.svg +[2]: http://JSON.org +[3]: https://twitter.com/TwoBitHistory +[4]: https://twobithistory.org/feed.xml diff --git a/published/20180326 Manage your workstation with Ansible- Automating configuration.md b/published/20180326 Manage your workstation with Ansible- Automating configuration.md new file mode 100644 index 0000000000..9f8c7a4b15 --- /dev/null +++ b/published/20180326 Manage your workstation with Ansible- Automating configuration.md @@ -0,0 +1,205 @@ +使用 Ansible 来管理你的工作站：配置自动化 +====== +> 学习如何使 Ansible 自动对一系列台式机和笔记本应用配置。 + +![](https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/robot_arm_artificial_ai.png?itok=8CUU3U_7) + +Ansible 是一个令人惊讶的自动化的配置管理工具。其主要应用在服务器和云部署上，但在工作站上的应用（无论是台式机还是笔记本）却鲜少得到关注，这就是本系列所要关注的。 + +在这个系列的[第一部分][1]，我向你展示了 `ansible-pull` 命令的基本用法，我们创建了一个安装了少量包的剧本。它本身是没有多大的用处的，但是为后续的自动化做了准备。 + +在这篇文章中，将会达成闭环，而且在最后部分，我们将会有一个针对工作站自动配置的完整的工作解决方案。现在，我们将要设置 Ansible 的配置，这样未来将要做的改变将会自动的部署应用到我们的工作站上。现阶段，假设你已经完成了[第一部分][1]的工作。如果没有的话，当你完成的时候回到本文。你应该已经有一个包含第一篇文章中代码的 GitHub 库。我们将直接在之前创建的部分之上继续。 + +首先，因为我们要做的不仅仅是安装包文件，所以我们要做一些重新的组织工作。现在，我们已经有一个名为 `local.yml` 并包含以下内容的剧本： + +``` +- hosts: localhost + become: true + tasks: + - name: Install packages + apt: name={{item}} + with_items: + - htop + - mc + - tmux +``` + +如果我们仅仅想实现一个任务那么上面的配置就足够了。随着向我们的配置中不断的添加内容，这个文件将会变的相当的庞大和杂乱。最好能够根据不同类型的配置将我们的动作play分为独立的文件。为了达到这个要求，创建一个名为任务手册taskbook的东西，它和剧本playbook很像但内容更加的流线型。让我们在 Git 库中为任务手册创建一个目录。 + +``` +mkdir tasks +``` + +`local.yml ` 剧本中的代码可以很好地过渡为安装包文件的任务手册。让我们把这个文件移动到刚刚创建好的 `task` 目录中，并重新命名。 + +``` +mv local.yml tasks/packages.yml +``` + +现在，我们编辑 `packages.yml` 文件将它进行大幅的瘦身，事实上，我们可以精简除了独立任务本身之外的所有内容。让我们把 `packages.yml` 编辑成如下的形式： + +``` +- name: Install packages + apt: name={{item}} + with_items: + - htop + - mc + - tmux +``` + +正如你所看到的，它使用同样的语法，但我们去掉了对这个任务无用没有必要的所有内容。现在我们有了一个专门安装包文件的任务手册。然而我们仍然需要一个名为 `local.yml` 的文件，因为执行 `ansible-pull` 命令时仍然会去找这个文件。所以我们将在我们库的根目录下（不是在 `task` 目录下）创建一个包含这些内容的全新文件： + +``` +- hosts: localhost + become: true + pre_tasks: + - name: update repositories + apt: update_cache=yes + changed_when: False + + tasks: + - include: tasks/packages.yml +``` + +这个新的 `local.yml` 扮演的是导入我们的任务手册的索引的角色。我已经在这个文件中添加了一些你在这个系列中还没见到的内容。首先，在这个文件的开头处，我添加了 `pre_tasks`，这个任务的作用是在其他所有任务运行之前先运行某个任务。在这种情况下，我们给 Ansible 的命令是让它去更新我们的发行版的软件库的索引，下面的配置将执行这个任务要求： + +``` +apt: update_cache=yes +``` + +通常 `apt` 模块是用来安装包文件的，但我们也能够让它来更新软件库索引。这样做的目的是让我们的每个动作在 Ansible 运行的时候能够以最新的索引工作。这将确保我们在使用一个老旧的索引安装一个包的时候不会出现问题。因为 `apt` 模块仅仅在 Debian、Ubuntu 及它们的衍生发行版下工作。如果你运行的一个不同的发行版，你要使用特定于你的发行版的模块而不是 `apt`。如果你需要使用一个不同的模块请查看 Ansible 的相关文档。 + +下面这行也需要进一步解释： + +``` +changed_when: False +``` + +在某个任务中的这行阻止了 Ansible 去报告动作改变的结果，即使是它本身在系统中导致的一个改变。在这里，我们不会去在意库索引是否包含新的数据；它几乎总是会的，因为库总是在改变的。我们不会去在意 `apt` 库的改变，因为索引的改变是正常的过程。如果我们删除这行，我们将在过程报告的后面看到所有的变动，即使仅仅库的更新而已。最好忽略这类的改变。 + +接下来是常规任务的阶段，我们将创建好的任务手册导入。我们每次添加另一个任务手册的时候，要添加下面这一行： + +``` +tasks: + - include: tasks/packages.yml +``` + +如果你现在运行 `ansible-pull` 命令，它应该基本上像上一篇文章中做的一样。不同的是我们已经改进了我们的组织方式，并且能够更有效的扩展它。为了节省你到上一篇文章中去寻找，`ansible-pull` 命令的语法参考如下： + +``` +sudo ansible-pull -U https://github.com//ansible.git +``` + +如果你还记得话，`ansible-pull` 的命令拉取一个 Git 仓库并且应用它所包含的配置。 + +既然我们的基础已经搭建好，我们现在可以扩展我们的 Ansible 并且添加功能。更特别的是，我们将添加配置来自动化的部署对工作站要做的改变。为了支撑这个要求，首先我们要创建一个特殊的账户来应用我们的 Ansible 配置。这个不是必要的，我们仍然能够在我们自己的用户下运行 Ansible 配置。但是使用一个隔离的用户能够将其隔离到不需要我们参与的在后台运行的一个系统进程中， + +我们可以使用常规的方式来创建这个用户，但是既然我们正在使用 Ansible，我们应该尽量避开使用手动的改变。替代的是，我们将会创建一个任务手册来处理用户创建任务。这个任务手册目前将会仅仅创建一个用户，但你可以在这个任务手册中添加额外的动作来创建更多的用户。我将这个用户命名为 `ansible`，你可以按照自己的想法来命名（如果你做了这个改变要确保更新所有出现地方）。让我们来创建一个名为 `user.yml` 的任务手册并且将以下代码写进去： + +``` +- name: create ansible user + user: name=ansible uid=900 +``` + +下一步，我们需要编辑 `local.yml` 文件，将这个新的任务手册添加进去，像如下这样写： + +``` +- hosts: localhost + become: true + pre_tasks: + - name: update repositories + apt: update_cache=yes + changed_when: False + + tasks: + - include: tasks/users.yml + - include: tasks/packages.yml +``` + +现在当我们运行 `ansible-pull` 命令的时候，一个名为 `ansible` 的用户将会在系统中被创建。注意我特地通过参数 `uid` 为这个用户声明了用户 ID 为 900。这个不是必须的，但建议直接创建好 UID。因为在 1000 以下的 UID 在登录界面是不会显示的，这样是很棒的，因为我们根本没有需要去使用 `ansibe` 账户来登录我们的桌面。UID 900 是随便定的；它应该是在 1000 以下没有被使用的任何一个数值。你可以使用以下命令在系统中去验证 UID 900 是否已经被使用了： + +``` +cat /etc/passwd |grep 900 +``` + +不过，你使用这个 UID 应该不会遇到什么问题，因为迄今为止在我使用的任何发行版中我还没遇到过它是被默认使用的。 + +现在，我们已经拥有了一个名为 `ansible` 的账户，它将会在之后的自动化配置中使用。接下来，我们可以创建实际的定时作业来自动操作。我们应该将其分开放到它自己的文件中，而不是将其放置到我们刚刚创建的 `users.yml` 文件中。在任务目录中创建一个名为 `cron.yml` 的任务手册并且将以下的代码写进去： + +``` +- name: install cron job (ansible-pull) + cron: user="ansible" name="ansible provision" minute="*/10" job="/usr/bin/ansible-pull -o -U https://github.com//ansible.git > /dev/null" +``` + +`cron` 模块的语法几乎不需加以说明。通过这个动作，我们创建了一个通过用户 `ansible` 运行的定时作业。这个作业将每隔 10 分钟执行一次，下面是它将要执行的命令： + +``` +/usr/bin/ansible-pull -o -U https://github.com//ansible.git > /dev/null +``` + +同样，我们也可以添加想要我们的所有工作站部署的额外的定时作业到这个文件中。我们只需要在新的定时作业中添加额外的动作即可。然而，仅仅是添加一个定时的任务手册是不够的，我们还需要将它添加到 `local.yml` 文件中以便它能够被调用。将下面的一行添加到末尾： + +``` +- include: tasks/cron.yml +``` + +现在当 `ansible-pull` 命令执行的时候，它将会以用户 `ansible` 每隔十分钟设置一个新的定时作业。但是，每个十分钟运行一个 Ansible 作业并不是一个好的方式，因为这个将消耗很多的 CPU 资源。每隔十分钟来运行对于 Ansible 来说是毫无意义的，除非我们已经在 Git 仓库中改变一些东西。 + +然而，我们已经解决了这个问题。注意我在定时作业中的命令 `ansible-pill` 添加的我们之前从未用到过的参数 `-o`。这个参数告诉 Ansible 只有在从上次 `ansible-pull` 被调用以后库有了变化后才会运行。如果库没有任何变化，它将不会做任何事情。通过这个方法，你将不会无端的浪费 CPU 资源。当然在拉取存储库的时候会使用一些 CPU 资源，但不会像再一次应用整个配置的时候使用的那么多。当 `ansible-pull` 执行的时候，它将会遍历剧本和任务手册中的所有任务，但至少它不会毫无目的的运行。 + +尽管我们已经添加了所有必须的配置要素来自动化 `ansible-pull`，它仍然还不能正常的工作。`ansible-pull` 命令需要 `sudo` 的权限来运行，这将允许它执行系统级的命令。然而我们创建的用户 `ansible` 并没有被设置为以 `sudo` 的权限来执行命令，因此当定时作业触发的时候，执行将会失败。通常我们可以使用命令 `visudo` 来手动的去设置用户 `ansible` 去拥有这个权限。然而我们现在应该以 Ansible 的方式来操作，而且这将会是一个向你展示 `copy` 模块是如何工作的机会。`copy` 模块允许你从库复制一个文件到文件系统的任何位置。在这个案列中，我们将会复制 `sudo` 的一个配置文件到 `/etc/sudoers.d/` 以便用户 `ansible` 能够以管理员的权限执行任务。 + +打开 `users.yml`，将下面的的动作添加到文件末尾。 + +``` +- name: copy sudoers_ansible + copy: src=files/sudoers_ansible dest=/etc/sudoers.d/ansible owner=root group=root mode=0440 +``` + +正如我们看到的，`copy`模块从我们的仓库中复制一个文件到其他任何位置。在这个过程中，我们正在抓取一个名为 `sudoers_ansible`（我们将在后续创建）的文件并将它复制为 `/etc/sudoers/ansible`，并且拥有者为 `root`。 + +接下来，我们需要创建我们将要复制的文件。在你的仓库的根目录下，创建一个名为 `files` 的目录： + +``` +mkdir files +``` + +然后，在我们刚刚创建的 `files` 目录里，创建名为 `sudoers_ansible` 的文件，包含以下内容： + +``` +ansible ALL=(ALL) NOPASSWD: ALL +``` + +就像我们正在这样做的，在 `/etc/sudoer.d` 目录里创建一个文件允许我们为一个特殊的用户配置 `sudo` 权限。现在我们正在通过 `sudo` 允许用户 `ansible` 不需要密码提示就拥有完全控制权限。这将允许 `ansible-pull` 以后台任务的形式运行而不需要手动去运行。 + +现在，你可以通过再次运行 `ansible-pull` 来拉取最新的变动： + +``` +sudo ansible-pull -U https://github.com//ansible.git +``` + +从这里开始，`ansible-pull` 的定时作业将会在后台每隔十分钟运行一次来检查你的仓库是否有变化，如果它发现有变化，将会运行你的剧本并且应用你的任务手册。 + +所以现在我们有了一个完整的可工作方案。当你第一次设置一台新的笔记本或者台式机的时候，你要去手动的运行 `ansible-pull` 命令，但仅仅是在第一次的时候。从第一次之后，用户 `ansible` 将会在后台接手后续的运行任务。当你想对你的机器做变动的时候，你只需要简单的去拉取你的 Git 仓库来做变动，然后将这些变化回传到库中。接着，当定时作业下次在每台机器上运行的时候，它将会拉取变动的部分并应用它们。你现在只需要做一次变动，你的所有工作站将会跟着一起变动。这方法尽管有一点不同寻常，通常，你会有一个包含你的机器列表和不同机器所属规则的清单文件。然而，`ansible-pull` 的方法，就像在文章中描述的，是管理工作站配置的非常有效的方法。 + +我已经在我的 [Github 仓库][2]中更新了这篇文章中的代码，所以你可以随时去浏览来对比检查你的语法。同时我将前一篇文章中的代码移到了它自己的目录中。 + +在[第三部分][3]，我们将通过介绍使用 Ansible 来配置 GNOME 桌面设置来结束这个系列。我将会告诉你如何设置你的墙纸和锁屏壁纸、应用一个桌面主题以及更多的东西。 + +同时，到了布置一些作业的时候了，大多数人都有我们所使用的各种应用的配置文件。可能是 Bash、Vim 或者其他你使用的工具的配置文件。现在你可以尝试通过我们在使用的 Ansible 库来自动复制这些配置到你的机器中。在这篇文章中，我已将向你展示了如何去复制文件，所以去尝试以下看看你是都已经能应用这些知识。 + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/18/3/manage-your-workstation-configuration-ansible-part-2 + +作者：[Jay LaCroix][a] +选题：[lujun9972](https://github.com/lujun9972) +译者：[FelixYFZ](https://github.com/FelixYFZ) +校对：[wxy](https://github.com/wxy) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]:https://opensource.com/users/jlacroix +[1]:https://linux.cn/article-10434-1.html +[2]:https://github.com/jlacroix82/ansible_article.git +[3]:https://opensource.com/article/18/5/manage-your-workstation-ansible-part-3 diff --git a/published/20180503 11 Methods To Find System-Server Uptime In Linux.md b/published/20180503 11 Methods To Find System-Server Uptime In Linux.md new file mode 100644 index 0000000000..865ee538df --- /dev/null +++ b/published/20180503 11 Methods To Find System-Server Uptime In Linux.md @@ -0,0 +1,188 @@ +Linux 上查看系统/服务器运行时间的 11 种方法 +====== + +你是否想知道自己的 Linux 系统正常运行了多长时间而没有宕机？系统是什么时候启动的？ + +Linux 上有多个查看服务器/系统运行时间的命令，大多数用户喜欢使用标准并且很有名的 `uptime` 命令获取这些具体的信息。 + +服务器的运行时间对一些用户来说不那么重要，但是当服务器运行诸如在线商城门户portal、网上银行门户等关键任务应用mission-critical applications时，它对于服务器管理员server adminstrators来说就至关重要。 + +它必须做到零宕机，因为一旦停机就会影响到数百万用户。 + +正如我所说，许多命令都可以让用户看到 Linux 服务器的运行时间。在这篇教程里我会教你如何使用下面 11 种方式来查看。 + +正常运行时间uptime指的是服务器自从上次关闭或重启以来经过的时间。 + +`uptime` 命令获取 `/proc` 文件中的详细信息并输出正常运行时间，而 `/proc` 文件并不适合人直接看。 + +以下这些命令会输出系统运行和启动的时间。也会显示一些额外的信息。 + +### 方法 1：使用 uptime 命令 + +`uptime` 命令会告诉你系统运行了多长时间。它会用一行显示以下信息。 + +当前时间、系统运行时间、当前登录用户的数量、过去 1 分钟/5 分钟/15 分钟系统负载的均值。 + +``` +# uptime + + 08:34:29 up 21 days, 5:46, 1 user, load average: 0.06, 0.04, 0.00 +``` + +### 方法 2：使用 w 命令 + +`w` 命令为每个登录进系统的用户，每个用户当前所做的事情，所有活动的负载对计算机的影响提供了一个快速的概要。这个单一命令结合了多个 Unix 程序：`who`、`uptime`，和 `ps -a` 的结果。 + +``` +# w + + 08:35:14 up 21 days, 5:47, 1 user, load average: 0.26, 0.09, 0.02 +USER TTY FROM LOGIN@ IDLE JCPU PCPU WHAT +root pts/1 103.5.134.167 08:34 0.00s 0.01s 0.00s w +``` + +### 方法 3：使用 top 命令 + +`top` 命令是 Linux 上监视实时系统进程的基础命令之一。它显示系统信息和运行进程的信息，例如正常运行时间、平均负载、运行的任务、登录用户数量、CPU 数量 & CPU 利用率、内存 & 交换空间信息。 + +**推荐阅读：**[TOP 命令监视服务器性能的例子][1] + +``` +# top -c + +top - 08:36:01 up 21 days, 5:48, 1 user, load average: 0.12, 0.08, 0.02 +Tasks: 98 total, 1 running, 97 sleeping, 0 stopped, 0 zombie +Cpu(s): 0.0%us, 0.3%sy, 0.0%ni, 99.7%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st +Mem: 1872888k total, 1454644k used, 418244k free, 175804k buffers +Swap: 2097148k total, 0k used, 2097148k free, 1098140k cached + + PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND + 1 root 20 0 19340 1492 1172 S 0.0 0.1 0:01.04 /sbin/init + 2 root 20 0 0 0 0 S 0.0 0.0 0:00.00 [kthreadd] + 3 root RT 0 0 0 0 S 0.0 0.0 0:00.00 [migration/0] + 4 root 20 0 0 0 0 S 0.0 0.0 0:34.32 [ksoftirqd/0] + 5 root RT 0 0 0 0 S 0.0 0.0 0:00.00 [stopper/0] +``` + +### 方法 4：使用 who 命令 + +`who` 命令列出当前登录进计算机的用户。`who` 命令与 `w` 命令类似，但后者还包含额外的数据和统计信息。 + +``` +# who -b +system boot 2018-04-12 02:48 +``` + +### 方法 5：使用 last 命令 + +`last` 命令列出最近登录过的用户。`last` 回溯 `/var/log/wtmp` 文件并显示自从文件创建后登录进（出）的用户。 + +``` +# last reboot -F | head -1 | awk '{print $5,$6,$7,$8,$9}' +Thu Apr 12 02:48:04 2018 +``` + +### 方法 6：使用 /proc/uptime 文件 + +这个文件中包含系统上次启动后运行时间的详细信息。`/proc/uptime` 的输出相当精简。 + +第一个数字是系统自从启动的总秒数。第二个数字是总时间中系统空闲所花费的时间，以秒为单位。 + +``` +# cat /proc/uptime +1835457.68 1809207.16 +``` + +### 方法 7：使用 tuptime 命令 + +`tuptime` 是一个汇报系统运行时间的工具，输出历史信息并作以统计，保留重启之间的数据。和 `uptime` 命令很像，但输出更有意思一些。 + +``` +$ tuptime +``` + +### 方法 8：使用 htop 命令 + +`htop` 是运行在 Linux 上的一个交互式进程查看器，是 Hisham 使用 ncurses 库开发的。`htop` 比起 `top` 有很多的特性和选项。 + +**推荐阅读：** [使用 Htop 命令监控系统资源][2] + +``` +# htop + + CPU[| 0.5%] Tasks: 48, 5 thr; 1 running + Mem[||||||||||||||||||||||||||||||||||||||||||||||||||| 165/1828MB] Load average: 0.10 0.05 0.01 + Swp[ 0/2047MB] Uptime: 21 days, 05:52:35 + + PID USER PRI NI VIRT RES SHR S CPU% MEM% TIME+ Command +29166 root 20 0 110M 2484 1240 R 0.0 0.1 0:00.03 htop +29580 root 20 0 11464 3500 1032 S 0.0 0.2 55:15.97 /bin/sh ./OSWatcher.sh 10 1 + 1 root 20 0 19340 1492 1172 S 0.0 0.1 0:01.04 /sbin/init + 486 root 16 -4 10780 900 348 S 0.0 0.0 0:00.07 /sbin/udevd -d + 748 root 18 -2 10780 932 360 S 0.0 0.0 0:00.00 /sbin/udevd -d +``` + +### 方法 9：使用 glances 命令 + +`glances` 是一个跨平台的基于 curses 库的监控工具，它是使用 python 编写的。可以说它非常强大，仅用一点空间就能获得很多信息。它使用 psutil 库从系统中获取信息。 + +`glances` 可以监控 CPU、内存、负载、进程、网络接口、磁盘 I/O、磁盘阵列RAID、传感器、文件系统（与文件夹）、容器、监视器、Alert 日志、系统信息、运行时间、快速查看Quicklook（CPU，内存、负载）等。 + +**推荐阅读：** [Glances （集大成）– Linux 上高级的实时系统运行监控工具][3] + +``` +glances + +ubuntu (Ubuntu 17.10 64bit / Linux 4.13.0-37-generic) - IP 192.168.1.6/24 Uptime: 21 days, 05:55:15 + +CPU [|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||| 90.6%] CPU - 90.6% nice: 0.0% ctx_sw: 4K MEM \ 78.4% active: 942M SWAP - 5.9% LOAD 2-core +MEM [||||||||||||||||||||||||||||||||||||||||||||||||||||||||| 78.0%] user: 55.1% irq: 0.0% inter: 1797 total: 1.95G inactive: 562M total: 12.4G 1 min: 4.35 +SWAP [|||| 5.9%] system: 32.4% iowait: 1.8% sw_int: 897 used: 1.53G buffers: 14.8M used: 749M 5 min: 4.38 + idle: 7.6% steal: 0.0% free: 431M cached: 273M free: 11.7G 15 min: 3.38 + +NETWORK Rx/s Tx/s TASKS 211 (735 thr), 4 run, 207 slp, 0 oth sorted automatically by memory_percent, flat view +docker0 0b 232b +enp0s3 12Kb 4Kb Systemd 7 Services loaded: 197 active: 196 failed: 1 +lo 616b 616b +_h478e48e 0b 232b CPU% MEM% VIRT RES PID USER NI S TIME+ R/s W/s Command + 63.8 18.9 2.33G 377M 2536 daygeek 0 R 5:57.78 0 0 /usr/lib/firefox/firefox -contentproc -childID 1 -isForBrowser -intPrefs 6:50|7:-1|19:0|34:1000|42:20|43:5|44:10|51 +DefaultGateway 83ms 78.5 10.9 3.46G 217M 2039 daygeek 0 S 21:07.46 0 0 /usr/bin/gnome-shell + 8.5 10.1 2.32G 201M 2464 daygeek 0 S 8:45.69 0 0 /usr/lib/firefox/firefox -new-window +DISK I/O R/s W/s 1.1 8.5 2.19G 170M 2653 daygeek 0 S 2:56.29 0 0 /usr/lib/firefox/firefox -contentproc -childID 4 -isForBrowser -intPrefs 6:50|7:-1|19:0|34:1000|42:20|43:5|44:10|51 +dm-0 0 0 1.7 7.2 2.15G 143M 2880 daygeek 0 S 7:10.46 0 0 /usr/lib/firefox/firefox -contentproc -childID 6 -isForBrowser -intPrefs 6:50|7:-1|19:0|34:1000|42:20|43:5|44:10|51 +sda1 9.46M 12K 0.0 4.9 1.78G 97.2M 6125 daygeek 0 S 1:36.57 0 0 /usr/lib/firefox/firefox -contentproc -childID 7 -isForBrowser -intPrefs 6:50|7:-1|19:0|34:1000|42:20|43:5|44:10|51 +``` + +### 方法 10：使用 stat 命令 + +`stat` 命令显示指定文件或文件系统的详细状态。 + +``` +# stat /var/log/dmesg | grep Modify +Modify: 2018-04-12 02:48:04.027999943 -0400 +``` + +### 方法 11：使用 procinfo 命令 + +`procinfo` 从 `/proc` 文件夹下收集一些系统数据并将其很好的格式化输出在标准输出设备上。 + +``` +# procinfo | grep Bootup +Bootup: Fri Apr 20 19:40:14 2018 Load average: 0.16 0.05 0.06 1/138 16615 +``` + +-------------------------------------------------------------------------------- + +via: https://www.2daygeek.com/11-methods-to-find-check-system-server-uptime-in-linux/ + +作者：[Magesh Maruthamuthu][a] +选题：[lujun9972](https://github.com/lujun9972) +译者：[LuuMing](https://github.com/LuuMing) +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/ +[1]:https://www.2daygeek.com/top-command-examples-to-monitor-server-performance/ +[2]:https://www.2daygeek.com/htop-command-examples-to-monitor-system-resources/ +[3]:https://www.2daygeek.com/install-glances-advanced-real-time-linux-system-performance-monitoring-tool-on-centos-fedora-ubuntu-debian-opensuse-arch-linux/ diff --git a/published/20181128 Turn an old Linux desktop into a home media center.md b/published/20181128 Turn an old Linux desktop into a home media center.md new file mode 100644 index 0000000000..e1acc79691 --- /dev/null +++ b/published/20181128 Turn an old Linux desktop into a home media center.md @@ -0,0 +1,89 @@ +[#]: collector: (lujun9972) +[#]: translator: (geekpi) +[#]: reviewer: (wxy) +[#]: publisher: (wxy) +[#]: subject: (Turn an old Linux desktop into a home media center) +[#]: via: (https://opensource.com/article/18/11/old-linux-desktop-new-home-media-center) +[#]: author: ([Alan Formy-Duval](https://opensource.com/users/alanfdoss)) +[#]: url: (https://linux.cn/article-10446-1.html) + +将旧的 Linux 台式机变成家庭媒体中心 +====== + +> 重新利用过时的计算机来浏览互联网并在大屏电视上观看视频。 + +![](https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/migration_innovation_computer_software.png?itok=VCFLtd0q) + +我第一次尝试搭建一台“娱乐电脑”是在 20 世纪 90 年代后期，使用了一台带 Trident ProVidia 9685 PCI 显卡的普通旧台式电脑。我使用了所谓的“电视输出”卡，它有一个额外的输出可以连接到标准电视端子上。屏幕显示看起来不太好，而且没有音频输出。并且外观很丑：有一条 S-Video 线穿过了客厅地板连接到我的 19 英寸 Sony Trinitron CRT 电视机上。 + +我在 Linux 和 Windows 98 上得到了同样令人遗憾的结果。在和那些看起来不对劲的系统挣扎之后，我放弃了几年。值得庆幸的是，如今的 HDMI 拥有更好的性能和标准化的分辨率，这使得廉价的家庭媒体中心成为现实。 + +我的新媒体中心娱乐电脑实际上是我的旧 Ubuntu Linux 桌面，最近我用更快的电脑替换了它。这台电脑在工作中太慢，但是它的 3.4GHz 的 AMD Phenom II X4 965 处理器和 8GB 的 RAM 足以满足一般浏览和视频流的要求。 + +以下是我让旧系统在新角色中发挥最佳性能所采取的步骤。 + +### 硬件 + +首先，我移除了不必要的设备，包括读卡器、硬盘驱动器、DVD 驱动器和后置 USB 卡，我添加了一块 PCI-Express 无线网卡。我将 Ubuntu 安装到单个固态硬盘 （SSD） 上，这可以切实提高任何旧系统的性能。 + +### BIOS + +在 BIOS 中，我禁用了所有未使用的设备，例如软盘和 IDE 驱动器控制器。我禁用了板载显卡，因为我安装了带 HDMI 输出的 NVidia GeForce GTX 650 PCI Express 显卡。我还禁用了板载声卡，因为 NVidia 显卡芯片组提供音频。 + +### 音频 + +Nvidia GeForce GTX 音频设备在 GNOME 控制中心的声音设置中被显示为 GK107 HDMI Audio Controller，因此单条 HDMI 线缆可同时处理音频和视频。无需将音频线连接到板载声卡的输出插孔。 + +![Sound settings screenshot][2] + +*GNOME 音频设置中的 HDMI 音频控制器。* + +### 键盘和鼠标 + +我有罗技的无线键盘和鼠标。当我安装它们时，我插入了两个外置 USB 接收器，它们可以使用，但我经常遇到信号反应问题。接着我发现其中一个被标记为联合接收器，这意味着它可以自己处理多个罗技输入设备。罗技不提供在 Linux 中配置联合接收器的软件。但幸运的是，有个开源程序 [Solaar][3] 能够做到。使用单个接收器解决了我的输入性能问题。 + +![Solaar][5] + +*Solaar 联合接收器界面。* + +### 视频 + +最初很难在我的 47 英寸平板电视上阅读文字，所以我在 Universal Access 下启用了“大文字”。我下载了一些与电视 1920x1080 分辨率相匹配的壁纸，这看起来很棒！ + +### 最后处理 + +我需要在电脑的冷却需求和我对不受阻碍的娱乐的渴望之间取得平衡。由于这是一台标准的 ATX 微型塔式计算机，我确保我有足够的风扇转速，以及在 BIOS 中精心配置过的温度以减少噪音。我还把电脑放在我的娱乐控制台后面，以进一步减少风扇噪音，但同时我可以按到电源按钮。 + +最后得到一台简单的、没有巨大噪音的机器，而且只使用了两根线缆：交流电源线和 HDMI。它应该能够运行任何主流或专门的媒体中心 Linux 发行版。我不期望去玩高端的游戏，因为这可能需要更多的处理能力。 + +![Showing Ubuntu Linux About page onscreen][7] + +*Ubuntu Linux 的关于页面。* + +![YouTube on the big screen][9] + +*在大屏幕上测试 YouTube 视频。* + +我还没安装像 [Kodi][10] 这样专门的媒体中心发行版。截至目前，它运行的是 Ubuntu Linux 18.04.1 LTS，而且很稳定。 + +这是一个有趣的挑战，可以充分利用我已经拥有的东西，而不是购买新的硬件。这只是开源软件的一个好处。最终，我可能会用一个更小，更安静的带有媒体中心的系统或其他小机顶盒替换它，但是现在，它很好地满足了我的需求。 + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/18/11/old-linux-desktop-new-home-media-center + +作者：[Alan Formy-Duval][a] +选题：[lujun9972][b] +译者：[geekpi](https://github.com/geekpi) +校对：[wxy](https://github.com/wxy) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://opensource.com/users/alanfdoss +[b]: https://github.com/lujun9972 +[2]: https://opensource.com/sites/default/files/uploads/soundsettings.png (Sound settings screenshot) +[3]: https://pwr.github.io/Solaar/ +[5]: https://opensource.com/sites/default/files/uploads/solaar_interface.png (Solaar) +[7]: https://opensource.com/sites/default/files/uploads/finalresult1.png (Showing Ubuntu Linux About page onscreen) +[9]: https://opensource.com/sites/default/files/uploads/finalresult2.png (YouTube on the big screen) +[10]: https://kodi.tv/ diff --git a/published/20181209 Powers of two, powers of Linux- 2048 at the command line.md b/published/20181209 Powers of two, powers of Linux- 2048 at the command line.md new file mode 100644 index 0000000000..1deb9a3c3d --- /dev/null +++ b/published/20181209 Powers of two, powers of Linux- 2048 at the command line.md @@ -0,0 +1,54 @@ +[#]: collector: (lujun9972) +[#]: translator: (geekpi) +[#]: reviewer: (wxy) +[#]: publisher: (wxy) +[#]: url: (https://linux.cn/article-10447-1.html) +[#]: subject: (Powers of two, powers of Linux: 2048 at the command line) +[#]: via: (https://opensource.com/article/18/12/linux-toy-2048) +[#]: author: (Jason Baker https://opensource.com/users/jason-baker) + +2 的威力，Linux 的威力：终端中的 2048 +====== + +> 正在寻找基于终端的游戏来打发时间么？来看看 2048-cli 吧。 + +![](https://opensource.com/sites/default/files/styles/image-full-size/public/uploads/linux-toy-2048.png?itok=3M6S-n1a) + +你好，欢迎来到今天的 Linux 命令行玩具日历。每天，我们会为你的终端带来一个不同的玩具：它可能是一个游戏或任何简单的消遣，可以帮助你获得乐趣。 + +很可能你们中的一些人之前已经看过我们日历中的各种玩具，但我们希望每个人至少见到一件新事物。 + +今天的玩具是我最喜欢的休闲游戏之一 [2048][2] （它本身就是另外一个克隆品的克隆）的[命令行版本][1]。 + +要进行游戏，你只需将滑块向上、向下、向左、向右移动，组合成对的数字，并增加数值，直到你得到数字为 2048 的块。最吸引人的地方（以及挑战）是你不能只移动一个滑块，而是需要移动屏幕上的每一块。（LCTT 译注：不知道有没有人在我们 Linux 中国的网站上遇到过 404 页面？那就是一个 2048 游戏，经常我错误地打开一个不存在的页面时，本应该去修复这个问题，却不小心沉迷于其中……） + +它简单、有趣，很容易在里面沉迷几个小时。这个 2048 的克隆 [2048-cli][1] 是 Marc Tiehuis 用 C 编写的，并在 MIT 许可下开源。你可以在 [GitHub][1] 上找到源代码，你也可在这找到适用于你的平台的安装说明。由于它已为 Fedora 打包，因此我来说，安装就像下面那样简单： + +``` +$ sudo dnf install 2048-cli +``` + +这是这样，玩得开心！ + +![](https://opensource.com/sites/default/files/uploads/linux-toy-2048-animated_0.gif) + +你有特别喜欢的命令行小玩具需要我介绍的吗？这个系列要介绍的小玩具大部分已经有了落实，但还预留了几个空位置。如果你有特别想了解的可以评论留言，我会查看的。如果还有空位置，我会考虑介绍它的。如果没有，但如果我得到了一些很好的意见，我会在最后做一些有价值的提及。 + +查看昨天的玩具，[在 Linux 终端中玩俄罗斯方块][3]，记得明天再来！ + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/18/12/linux-toy-2048 + +作者：[Jason Baker][a] +选题：[lujun9972][b] +译者：[geekpi](https://github.com/geekpi) +校对：[wxy](https://github.com/wxy) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://opensource.com/users/jason-baker +[b]: https://github.com/lujun9972 +[1]: https://github.com/tiehuis/2048-cli +[2]: https://github.com/gabrielecirulli/2048 +[3]: https://opensource.com/article/18/12/linux-toy-tetris diff --git a/published/20181212 5 resolutions for open source project maintainers.md b/published/20181212 5 resolutions for open source project maintainers.md new file mode 100644 index 0000000000..b39ffc1a51 --- /dev/null +++ b/published/20181212 5 resolutions for open source project maintainers.md @@ -0,0 +1,66 @@ +[#]: collector: (lujun9972) +[#]: translator: (bestony) +[#]: reviewer: (wxy) +[#]: publisher: (wxy) +[#]: url: (https://linux.cn/article-10448-1.html) +[#]: subject: (5 resolutions for open source project maintainers) +[#]: via: (https://opensource.com/article/18/12/resolutions-open-source-project-maintainers) +[#]: author: (Ben Cotton https://opensource.com/users/bcotton) + +一位开源项目维护者的 5 个决心 +====== + +> 不管怎么说，好的交流是一个活跃的开源社区的必备品。 + +![](https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/spark_sparkler_fire_new_year_idea.png?itok=rnyMpVP8) + +我通常不会定下大的新年决心。当然，我在自我提升方面没有任何问题，这篇文章我希望锚定的是这个日历中的另外一部分。不过即使是这样，这里也有一些东西要从今年的免费日历上划掉，并将其替换为一些可以激发我的自省的新日历内容。 + +在 2017 年，我从不在社交媒体上分享我从未阅读过的文章。我一直保持这样的状态，我也认为它让我成为了一个更好的互联网公民。对于 2019 年，我正在考虑让我成为更好的开源软件维护者的决心。 + +下面是一些我在一些项目中担任维护者或共同维护者时坚持的决心： + +### 1、包含行为准则 + +Jono Bacon 在他的文章“[7 个你可能犯的错误][1]”中包含了一条“不强制执行行为准则”。当然，要强制执行行为准则，你首先需要有一个行为准则。我打算默认用[贡献者契约][2]，但是你可以使用其他你喜欢的。关于这个许可协议，最好的方法是使用别人已经写好的，而不是你自己写的。但是重要的是，要找到一些能够定义你希望你的社区执行的，无论它们是什么样子。一旦这些被记录下来并强制执行，人们就能自行决定是否成为他们想象中社区的一份子。 + +### 2、使许可证清晰且明确 + +你知道什么真的很烦么？不清晰的许可证。"这个软件基于 GPL 授权"，如果没有进一步提供更多信息的文字，我无法知道更多信息。基于哪个版本的[GPL][3]？我可以用它吗？对于项目的非代码部分，“根据知识共享许可证（CC）授权”更糟糕。我喜欢[知识共享许可证][4]，但它有几个不同的许可证包含着不同的权利和义务。因此，我将非常清楚的说明哪个许可证的变种和版本适用于我的项目。我将会在仓库中包含许可的全文，并在其他文件中包含简明的注释。 + +与此相关的一类问题是使用 [OSI][5] 批准的许可证。想出一个新的准确的说明了你想要表达什么的许可证是有可能的，但是如果你需要强制推行它，祝你好运。会坚持使用它么？使用您项目的人会理解么？ + +### 3、快速分类错误报告和问题 + +在技术领域, 很少有比开源维护者更贫乏的东西了。即使在小型项目中，也很难找到时间去回答每个问题并修复每个错误。但这并不意味着我不能哪怕回应一下，它没必要是多段的回复。即使只是给 GitHub 问题贴了个标签也表明了我看见它了。也许我马上就会处理它，也许一年后我会处理它。但是让社区看到它很重要，是的，这里还有人管。 + +### 4、如果没有伴随的文档，请不要推送新特性或错误修复 + +尽管多年来我的开源贡献都围绕着文档，但我的项目并没有反映出我对它的重视。我能推送的提交不多，并不不需要某种形式的文档。新的特性显然应该在他们被提交时甚至是在之前就编写文档。但即使是错误修复，也应该在发行说明中有一个条目提及。如果没有什么意外，推送提交也是很好的改善文档的机会。 + +### 5、放弃一个项目时，要说清楚 + +我很不擅长对事情说“不”，我告诉编辑我会为 [Opensource.com][6] 写一到两篇文章，而现在我有了将近 60 篇文章。哎呀。但在某些时候，曾经我有兴趣的事情也会不再有兴趣。也许该项目是不必要的，因为它的功能被吸收到更大的项目中；也许只是我厌倦了它。但这对社区是不公平的（并且存在潜在的危险，正如最近的 [event-stream 恶意软件注入][7]所示），会让该项目陷入困境。维护者有权随时离开，但他们离开时应该说清楚。 + +无论你是开源维护者还是贡献者，如果你知道项目维护者应该作出的其他决心，请在评论中分享！ + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/18/12/resolutions-open-source-project-maintainers + +作者：[Ben Cotton][a] +选题：[lujun9972][b] +译者：[bestony](https://github.com/bestony) +校对：[wxy](https://github.com/wxy) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://opensource.com/users/bcotton +[b]: https://github.com/lujun9972 +[1]: https://opensource.com/article/17/8/mistakes-open-source-avoid +[2]: https://www.contributor-covenant.org/ +[3]: https://opensource.org/licenses/gpl-license +[4]: https://creativecommons.org/share-your-work/licensing-types-examples/ +[5]: https://opensource.org/ +[6]: http://Opensource.com +[7]: https://arstechnica.com/information-technology/2018/11/hacker-backdoors-widely-used-open-source-software-to-steal-bitcoin/ diff --git a/translated/tech/20181218 Termtosvg - Record Your Terminal Sessions As SVG Animations In Linux.md b/published/20181218 Termtosvg - Record Your Terminal Sessions As SVG Animations In Linux.md similarity index 75% rename from translated/tech/20181218 Termtosvg - Record Your Terminal Sessions As SVG Animations In Linux.md rename to published/20181218 Termtosvg - Record Your Terminal Sessions As SVG Animations In Linux.md index 45219568f8..eb125ef003 100644 --- a/translated/tech/20181218 Termtosvg - Record Your Terminal Sessions As SVG Animations In Linux.md +++ b/published/20181218 Termtosvg - Record Your Terminal Sessions As SVG Animations In Linux.md @@ -1,34 +1,24 @@ [#]: collector: (lujun9972) [#]: translator: (zhs852) -[#]: reviewer: ( ) -[#]: publisher: ( ) -[#]: url: ( ) +[#]: reviewer: (wxy) +[#]: publisher: (wxy) +[#]: url: (https://linux.cn/article-10441-1.html) [#]: subject: (Termtosvg – Record Your Terminal Sessions As SVG Animations In Linux) [#]: via: (https://www.2daygeek.com/termtosvg-record-your-terminal-sessions-as-svg-animations-in-linux/) [#]: author: (Magesh Maruthamuthu https://www.2daygeek.com/author/magesh/) -Termtosvg – 将你在 Linux 终端中操作录制成 SVG 动画 +Termtosvg：将你在 Linux 终端中操作录制成 SVG 动画 ====== -一般人喜欢使用历史命令功能来查看/再次调用之前在终端中输入的命令。 +一般人喜欢使用历史命令功能来查看/再次调用之前在终端中输入的命令。不幸的是，那样做只会显示先前输入的命令，而不是之前输出的内容。 -不幸的是，那样做只会显示先前输入的命令，而不是之前输出的内容。 - -在 Linux 中，有许多可以用来记录终端活动的实用工具。 - -这种工具将会帮助我们记录用户在终端中的活动，并帮助我们识别输出中有用的信息。 +在 Linux 中，有许多可以用来记录终端活动的实用工具。这种工具将会帮助我们记录用户在终端中的活动，并帮助我们识别输出中有用的信息。 在这之前，我们已经介绍了一些这类实用工具了。今天，让我们接着讨论这类工具。 -如果你希望尝试其它一些记录你终端活动的工具，我推荐你试试 **[Script Command][1]** 和 **[Terminalizer Tool][2]**。 +如果你希望尝试其它一些记录你终端活动的工具，我推荐你试试 [script][1] 命令和 [Terminalizer][2] 工具。`script` 是在无头服务器中记录终端活动的最佳方式之一。`script` 是一个记录在终端中输入过的 Unix 命令的实用工具（在某些终端中，它会记录显示在你终端中的所有东西）。它会在当前工作目录下以文本文件方式储存所有终端输出。 -不过，如果你在寻找 **[GIF 录制器][3]** ，你可以尝试 **[Gifine][4]** 、**[Kgif][5]** 和 **[Peek][6]** 。 - -脚本是在无头服务器中记录终端活动的最佳方式之一。 - -脚本是记录在终端中输入过的 Unix 命令的实用工具（在某些终端中，它会记录显示在你终端中的所有东西）。 - -它会在当前工作目录下以文本文件方式储存所有终端输出。 +不过，如果你在寻找 [GIF 录制器][3] ，你可以尝试 [Gifine][4]、[Kgif][5] 和 [Peek][6]。 ### 什么是 Termtosvg @@ -36,47 +26,47 @@ Termtosvg 是一个用 Python 编写的 Unix 终端录制器，它可以将你 ### Termtosvg 的特点 - * 可以制作用于某个项目主页且简洁美观的动画。 + * 可以制作嵌入于项目主页的简洁美观的动画。 * 可以在 SVG 模板中自定义配色、终端 UI 和动画。 * 兼容 asciinema 录制格式。 * 要求 Python 版本为 3.5 或更高。 ### 如何在 Linux 中安装 Termtosvg -它是用 Python 编写的，所以我推荐使用 pip 来安装它。 +它是用 Python 编写的，所以我推荐使用 `pip` 来安装它。 -请确保你已经安装了 **python-pip** 包。如果你还没安装，请输入下面的命令。 -对于 Debian 或 Ubuntu 用户，请使用 **[apt][7]** 或 **[apt-get][8]** 来安装 pip。 +请确保你已经安装了 python-pip 包。如果你还没安装，请输入下面的命令。 +对于 Debian 或 Ubuntu 用户，请使用 [apt][7] 或 [apt-get][8] 来安装 `pip`。 ```shell sudo apt install python-pip ``` -对于 Archlinux 用户，请使用 **[pacman][9]** 来安装 pip。 +对于 Archlinux 用户，请使用 [pacman][9] 来安装 `pip`。 ```shell sudo pacman -S python-pip ``` -对于 Fedora 用户，请使用 **[dnf][10]** 来安装 pip。 +对于 Fedora 用户，请使用 [dnf][10] 来安装 `pip`。 ```shell sudo dnf install python-pip ``` -对于 CentOS 或 RHEL 用户，请使用 **[yum][11]** 来安装 pip。 +对于 CentOS 或 RHEL 用户，请使用 [yum][11] 来安装 `pip`。 ```shell sudo yum install python-pip ``` -对于 openSUSE 用户，请使用 **[zypper][12]** 来安装 pip。 +对于 openSUSE 用户，请使用 [zypper][12] 来安装 `pip`。 ```shell sudo zypper install python-pip ``` -最后，请执行 **[pip][13]** 来安装 Termtosvg。 +最后，请执行 [pip][13] 来安装 Termtosvg。 ```shell sudo pip3 install termtosvg pyte python-xlib svgwrite diff --git a/translated/tech/20181221 An Easy Way To Remove Programs Installed From Source In Linux.md b/published/20181221 An Easy Way To Remove Programs Installed From Source In Linux.md similarity index 51% rename from translated/tech/20181221 An Easy Way To Remove Programs Installed From Source In Linux.md rename to published/20181221 An Easy Way To Remove Programs Installed From Source In Linux.md index f33ff7af14..12411f8aa0 100644 --- a/translated/tech/20181221 An Easy Way To Remove Programs Installed From Source In Linux.md +++ b/published/20181221 An Easy Way To Remove Programs Installed From Source In Linux.md @@ -1,62 +1,61 @@ [#]: collector: (lujun9972) -[#]: translator: ( dianbanjiu ) -[#]: reviewer: ( ) -[#]: publisher: ( ) -[#]: url: ( ) +[#]: translator: (dianbanjiu) +[#]: reviewer: (wxy) +[#]: publisher: (wxy) +[#]: url: (https://linux.cn/article-10438-1.html) [#]: subject: (An Easy Way To Remove Programs Installed From Source In Linux) [#]: via: (https://www.ostechnix.com/an-easy-way-to-remove-programs-installed-from-source-in-linux/) [#]: author: (SK https://www.ostechnix.com/author/sk/) -在 Linux 中移除从源中安装的程序的一种简单的方法 +在 Linux 中移除从源代码安装的程序的一种简单的方法 ====== ![](https://www.ostechnix.com/wp-content/uploads/2018/12/stow-1-720x340.jpg) -不是所有的程序都可以在官方或者第三方库中可用，因此你不能使用常规的包管理来安装它们。有时你不得不从源代码中手动构建这些程序。就跟你已经知道的一样，当你从源代码中安装一个程序的时候，这个包文件将会复制到本地的多个位置，例如 **/usr/local/bin**，**/usr/local/etc/**。如果从源代码中安装的程序没有内建的卸载器，当你不再需要这个程序的时候，卸载它就会很麻烦。你可能会话费双倍（甚至更多）的时间找出这些包文件然后手动删除它们。我以前一直是这样做的，直到我发现了 **GNU Stow**。谢天谢地，Stow 有一个很棒的方法可以轻松管理从源代码安装的程序。 - +不是所有的程序都可以在官方或者第三方库中找到，因此你不能使用常规的包管理来安装它们。有时你不得不从源代码中手动构建这些程序。就如你已经知道的一样，当你从源代码中安装一个程序的时候，这个软件包所包含的文件将会复制到本地的多个位置，例如 `/usr/local/bin`、`/usr/local/etc/`。如果从源代码中安装的程序没有内置的卸载程序，当你不再需要这个程序的时候，卸载它就会很麻烦。你可能会花费双倍（甚至更多）的时间找出这些文件然后手动删除它们。我以前一直是这样做的，直到我发现了 GNU Stow。谢天谢地，Stow 有一个很棒的方法可以轻松管理从源代码安装的程序。 引用官方网站里的一段介绍， -> **GNU Stow 是一个符号链接管理器，它可以收集文件系统上不同目录中的不同软件和/或数据包，使它们看起来像是一个整体** +> GNU Stow 是一个符号链接归集管理器，它可以收集文件系统上不同目录中的不同软件和/或数据包，使它们看起来像是一个整体。 -简单来说，Stow 帮助你把这些程序文件以一种容易管理的方式组织在了一起。在这个方法中，文件将不会被复制到多个位置。所有的这些文件都会被保存在一个特定的文件夹中，通常是以程序名命名的，然后 Stow 会在一个合适的位置为所有的程序文件创建符号连接。比如 **/usr/local/bin** 中会包含 **/usr/local/stow/vim/bin**，**/usr/local/stow/python/bin** 中文件的符号链接。并且同样递归地用于其他的任何的子目录，例如 **.../share**，**.../man**，等等。在这篇教程中，我将会举例教你如何轻松地使用 Stow 管理从源中安装的程序。 +简单来说，Stow 帮助你把这些程序文件以一种容易管理的方式组织在了一起。在这个方法中，文件将不会被复制到多个位置。所有的这些文件都会被保存在一个特定的文件夹中，通常是以程序名命名的，然后 Stow 会在一个合适的位置为所有的程序文件创建符号连接。比如 `/usr/local/bin` 中会包含 `/usr/local/stow/vim/bin`、`/usr/local/stow/python/bin` 中文件的符号链接。并且同样递归地用于其他的任何的子目录，例如 `.../share`、`.../man`，等等。在这篇教程中，我将会举例教你如何轻松地使用 Stow 管理从源中安装的程序。 ### 安装 GNU Stow GNU Stow 在流行 Linux 操作系统的默认库中都可用。 -在 **Arch Linux** 及它的衍生版本中，运行下面的命令安装 Stow。 +在 Arch Linux 及它的衍生版本中，运行下面的命令安装 Stow。 ``` $ sudo pacman -S stow ``` -在 **Debian**，**Ubuntu**，**Linux Mint** 上： +在 Debian、Ubuntu、Linux Mint 上： ``` $ sudo apt install stow ``` -在 **Fedora** 上： +在 Fedora 上： ``` $ sudo dnf install stow ``` -在 **RHEL/CentOS** 上： + +在 RHEL/CentOS 上： ``` $ sudo yum install epel-release - $ sudo yum install stow ``` ### 在 Linux 上轻松移除从源代码安装的程序 -就像我之前提到的，所有包的程序文件都将被保存在位于 **/usr/local/stow/** 的一个根文件夹。在这个根文件夹或者父目录之下，每个包都将保存在对应的子目录中。例如，如果我们从源代码中安装了 Vim 编辑器，所有关联到 Vim 的程序文件和目录都将保存在 **/usr/local/stow/vim** 文件夹之下。如果你从源代码中安装了 Python，所有关联到 python 的文件都会保存在 **/usr/local/stow/python** 之下。 +就像我之前提到的，所有包的程序文件都将被保存在位于 `/usr/local/stow/` 的一个根文件夹。在这个根文件夹或者父目录之下，每个包都将保存在对应的子目录中。例如，如果我们从源代码中安装了 Vim 编辑器，所有关联到 Vim 的程序文件和目录都将保存在 `/usr/local/stow/vim` 文件夹之下。如果你从源代码中安装了 Python，所有关联到 python 的文件都会保存在 `/usr/local/stow/python` 之下。 -我现在从源代码中来安装一个叫做 **hello** 的程序。 +我现在从源代码中来安装一个叫做 hello 的程序。 -首先下载 ‘hello’ 程序的压缩包。 +首先下载 hello 程序的压缩包。 ``` $ wget http://ftp.gnu.org/gnu/hello/hello-2.10.tar.gz @@ -68,7 +67,7 @@ $ wget http://ftp.gnu.org/gnu/hello/hello-2.10.tar.gz $ tar -zxvf hello-2.10.tar.gz ``` -上面的命令将会在当前工作目录下创建一个叫做 ‘hello-2.10’ 的目录，并且提取压缩包中的所有内容到其中去。 +上面的命令将会在当前工作目录下创建一个叫做 `hello-2.10` 的目录，并且提取压缩包中的所有内容到其中去。 切换到这个目录当中： @@ -76,42 +75,40 @@ $ tar -zxvf hello-2.10.tar.gz $ cd hello-2.10/ ``` -运行下面的命令，并且添加 -prefix 选项。 +运行下面的命令，并且添加 `-prefix` 选项。 ``` $ ./configure --prefix=/usr/local/stow/hello ``` -上面的命令将会保存构建文件到一个指定位置，在这个例子中是 **/usr/local/stow/hello**。 +上面的命令将会保存构建文件到一个指定位置，在这个例子中是 `/usr/local/stow/hello`。 最后，使用下面的命令构建并安装 hello 这个程序： ``` $ make - $ sudo make install ``` -就这样。hello 这个程序就已经安装在 **/usr/local/stow/hello/** 这个位置了。你可以使用下面的 ‘ls’ 命令确认一下。 +就这样。hello 这个程序就已经安装在 `/usr/local/stow/hello/` 这个位置了。你可以使用下面的 `ls` 命令确认一下。 ``` $ ls /usr/local/stow/hello/ bin share ``` -最后，进入 **/usr/local/stow/** 目录，运行下面的命令来生成必要的符号链接。 +最后，进入 `/usr/local/stow/` 目录，运行下面的命令来生成必要的符号链接。 ``` $ cd /usr/local/stow/ - $ sudo stow hello ``` 大功告成！ -刚才那一步是将包含在 hello 这个程序中的所有文件或者目录创建了链接到 **/usr/local/** 目录中。换一种说法， **/usr/local/stow/hello/bin** 已经链接到 **/usr/local/share**，以及 **/usr/local/stow/hello/share/man** 已经链接到 **/usr/local/share**，还有 **/usr/local/stow/hello/share/man** 已经链接到 **/usr/local/share/man**。 +刚才那一步是将包含在 hello 这个程序中的所有文件或者目录创建了链接到 `/usr/local/` 目录中。换一种说法， `/usr/local/stow/hello/bin` 链接到 `/usr/local/share`，以及 `/usr/local/stow/hello/share/man` 链接到 `/usr/local/share`，还有 `/usr/local/stow/hello/share/man` 链接到 `/usr/local/share/man`。 -你可以使用 ‘ls’ 命令来确认一下： +你可以使用 `ls` 命令来确认一下： ``` $ ls /usr/local/bin/ @@ -137,15 +134,15 @@ $ tree /usr/local/stow/ ![][2] -看，hello 这个程序已经安装在 /usr/local/stow/hello/ 下。同样地，所有的包都将保存在它们对应的目录之下。 +看，hello 这个程序已经安装在 `/usr/local/stow/hello/` 下。同样地，所有的包都将保存在它们对应的目录之下。 -下面进入主要环节，移除 hello 这个程序。首先进入 **/usr/local/stow/** 目录： +下面进入主要环节，移除 hello 这个程序。首先进入 `/usr/local/stow/` 目录： ``` $ cd /usr/local/stow/ ``` -.. 然后运行下面的命令： +然后运行下面的命令： ``` $ sudo stow --delete hello @@ -162,7 +159,7 @@ $ hello 看， Hello 已经被移除了！ -请注意 Stow 仅仅只移除了符号链接。所有与 hello 这个程序相关的文件或者目录还保存在 **/usr/local/stow/hello** 目录下。所以你无需再次下载源文件就可以再次安装 hello 这个程序。如果你不再需要它了，直接删除这个文件夹即可。 +请注意 Stow 仅仅只移除了符号链接。所有与 hello 这个程序相关的文件或者目录还保存在 `/usr/local/stow/hello` 目录下。所以你无需再次下载源文件就可以再次安装 hello 这个程序。如果你不再需要它了，直接删除这个文件夹即可。 ``` $ sudo rm -fr /usr/local/stow/hello/ @@ -174,22 +171,20 @@ $ sudo rm -fr /usr/local/stow/hello/ $ man stow ``` - Stow 可以像安装程序一样轻松地帮你移除它。如果你想知道如何高效的管理很多从源代码中安装的程序，GNU Stow 就是一个使得这个任务更加轻松的一个选择，尝试一下，你一定不会失望的。 这就是所有的内容了，希望对你有所帮助。还有更多干活即将到来，可以期待一下的！ 祝近祺！ - -------------------------------------------------------------------------------- via: https://www.ostechnix.com/an-easy-way-to-remove-programs-installed-from-source-in-linux/ 作者：[SK][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：[dianbanjiu](https://github.com/dianbanjiu) +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 diff --git a/translated/tech/20190103 How to create presentations with Beamer.md b/published/20190103 How to create presentations with Beamer.md similarity index 62% rename from translated/tech/20190103 How to create presentations with Beamer.md rename to published/20190103 How to create presentations with Beamer.md index 8e98d98561..255db4e77a 100644 --- a/translated/tech/20190103 How to create presentations with Beamer.md +++ b/published/20190103 How to create presentations with Beamer.md @@ -1,15 +1,17 @@ [#]: collector: (lujun9972) [#]: translator: (geekpi) -[#]: reviewer: ( ) -[#]: publisher: ( ) -[#]: url: ( ) +[#]: reviewer: (wxy) +[#]: publisher: (wxy) +[#]: url: (https://linux.cn/article-10439-1.html) [#]: subject: (How to create presentations with Beamer) [#]: via: (https://opensource.com/article/19/1/create-presentations-beamer) [#]: author: (Moshe Zadka https://opensource.com/users/moshez) 如何使用 Beamer 创建演示文稿 ====== -Beamer 将 LaTeX 强大的排版功能和生态系统带进创建幻灯片中。 + +> Beamer 将 LaTeX 强大的排版功能和生态系统带进创建幻灯片中。 + ![](https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/bus_presentation.png?itok=CQeyO61b) [Beamer][1] 是用于生成幻灯片的 LaTeX 包。它最棒的功能之一是它可以利用 LaTeX 强大的排版系统和其生态系统中的所有其他软件包。例如，我经常在包含代码的 Beamer 演示文稿中使用 LaTeX 的 [listings][2] 包。 @@ -22,25 +24,25 @@ Beamer 将 LaTeX 强大的排版功能和生态系统带进创建幻灯片中。 \documentclass{beamer} ``` -与任何其他 LaTeX 文档一样，添加你要使用的任何包。例如，要使用 **listings** 包，请输入： +与任何其他 LaTeX 文档一样，添加你要使用的任何包。例如，要使用 `listings` 包，请输入： ``` \usepackage{listings} ``` -将所有内容放在 **document** 环境中： +将所有内容放在 `document` 环境中： ``` \begin{document} ``` -Beamer 文档通常时是一系列的 **frame** 环境。包含代码的 frame 应该被标记为 **fragile**： +Beamer 文档通常时是一系列的 `frame` 环境。包含代码的 `frame` 应该被标记为 `fragile`： ``` \begin{frame}[fragile] ``` -使用标题开始你的 frame： +使用标题开始你的 `frame`： ``` \frametitle{Function to Do Stuff} @@ -48,11 +50,11 @@ Beamer 文档通常时是一系列的 **frame** 环境。包含代码的 frame ### 开始演示前测试你的代码 -世上最糟糕的感受之一你在演讲中说到代码时，突然发现了一个 bug—也许是拼错了关键词或者漏掉了括号。 +世上最糟糕的感受之一你在演讲中说到代码时，突然发现了一个 bug —— 也许是拼错了关键词或者漏掉了括号。 解决方法之一就是测试演示的代码。在多数演示环境中，这意味着创建一个单独的文件、编写测试接着拷贝和粘贴。 -然而，在 Beamer 中有一种更好的方法。想象一下，你有一个名为 **do_stuff.py** 的文件，其中包含代码。你可以在第二个文件中编写 **do_stuff.py** 代码的测试，你可以将其命名为 **test_do_stuff.py**，并且可以使用 [pytest][3] 测试。但是，**do_stuff.py**中的大多数行都缺乏教学价值，比如定义辅助函数。 +然而，在 Beamer 中有一种更好的方法。想象一下，你有一个名为 `do_stuff.py` 的文件，其中包含代码。你可以在第二个文件中编写 `do_stuff.py` 代码的测试，你可以将其命名为 `test_do_stuff.py`，并且可以使用 [pytest][3] 测试。但是，`do_stuff.py` 中的大多数行都缺乏教学价值，比如定义辅助函数。 要简化你受众看到的东西，你可在演示文稿中只导入你要讨论的行到 frame 中： @@ -64,13 +66,13 @@ Beamer 文档通常时是一系列的 **frame** 环境。包含代码的 frame ]{do_stuff.py} ``` -由于你会对这几行（从 8 到 15）进行讨论，因此幻灯片上不需要任何其他内容。结束 frame： +由于你会对这几行（从 8 到 15）进行讨论，因此幻灯片上不需要任何其他内容。结束 `frame`： ``` \end{frame} ``` -在下一张幻灯片中，你想展示刚才的 **do_stuff()** 函数的用法示例： +在下一张幻灯片中，你想展示刚才的 `do_stuff()` 函数的用法示例： ``` \begin{frame}[fragile] @@ -83,15 +85,15 @@ Beamer 文档通常时是一系列的 **frame** 环境。包含代码的 frame \end{frame} ``` -你使用相同的文件，但这次显示调用该函数的行。最后，结束 document： +你使用相同的文件，但这次显示调用该函数的行。最后，结束 `document`： ``` \end{document} ``` -假设你在 **do_stuff.py** 中有一个合适的 Python 文件，这将生成一个含有 2 页的幻灯片。 +假设你在 `do_stuff.py` 中有一个合适的 Python 文件，这将生成一个含有 2 页的幻灯片。 -Beamer 还支持必要的功能如渐进式演示，每次给观众展示一部分以免受到前面的打扰。在行中放入 ”**\pause**“ 会将页面分成不同的部分： +Beamer 还支持必要的功能如渐进式演示，每次给观众展示一部分以免受到前面的打扰。在行中放入 `\pause` 会将页面分成不同的部分： ``` \begin{frame} @@ -107,18 +109,18 @@ Remember: ### 创建讲义 -Beamer 中我最喜欢的功能是你可以用 **\documentclass[ignorenonframetext]{beamer}** 设置忽略 frame 外的所有内容。当我准备演示文稿时，我离开顶部（声明文档类的位置）并自动生成它的两个版本：我的演示稿使用 Beamer 忽略任何 frame 之外的所有文本，另一个含有类似这样的头： +Beamer 中我最喜欢的功能是可以用 `\documentclass[ignorenonframetext]{beamer}` 设置忽略 `frame` 外的所有内容。当我准备演示文稿时，我离开顶部（声明文档类的位置）并自动生成它的两个版本：我的演示稿使用 Beamer 忽略任何 `frame` 之外的所有文本，另一个含有类似这样的头： ``` \documentclass{article} \usepackage{beamerarticle} ``` -这会生成一份讲义—一份含有所有 frame 和它们之间文字的 PDF。 +这会生成一份讲义：一份含有所有 `frame` 和它们之间文字的 PDF。 当会议组织者要求我发布我的幻灯片时，我会包含原始幻灯片作为参考，但我希望人们拿到的是讲义，它包含了所有我不想在幻灯片上写的解释部分。 -在创建幻灯片时，人们经常想是要为演讲优化资料还是方便那些想要日后阅读的人。幸运的是，Beamer 提供了两全其美的办法。 +在创建幻灯片时，人们经常会考虑是为演讲优化讲稿还是为之后想要阅读它的人们优化。幸运的是，Beamer 提供了两全其美的办法。 -------------------------------------------------------------------------------- @@ -127,7 +129,7 @@ via: https://opensource.com/article/19/1/create-presentations-beamer 作者：[Moshe Zadka][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 @@ -135,4 +137,4 @@ via: https://opensource.com/article/19/1/create-presentations-beamer [b]: https://github.com/lujun9972 [1]: https://www.overleaf.com/learn/latex/Beamer [2]: https://www.overleaf.com/learn/latex/Code_listing -[3]: https://docs.pytest.org/en/latest/ \ No newline at end of file +[3]: https://docs.pytest.org/en/latest/ diff --git a/sources/talk/20150513 XML vs JSON.md b/sources/talk/20150513 XML vs JSON.md new file mode 100644 index 0000000000..d3928daa83 --- /dev/null +++ b/sources/talk/20150513 XML vs JSON.md @@ -0,0 +1,107 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (XML vs JSON) +[#]: via: (https://www.cs.tufts.edu/comp/150IDS/final_papers/tstras01.1/FinalReport/FinalReport.html#xml-advantages) +[#]: author: (TOM STRASSNER tomstrassner@gmail.com) + +XML vs JSON +====== + +### Introduction + +XML and JSON are the two most common formats for data interchange in the Web today. XML was created by the W3C in 1996, and JSON was publicly specified by Douglas Crockford in 2002. Although their purposes are not identical, they are frequently used to accomplish the same task, which is data interchange. Both have well-documented open standards on the Web ([RFC 7159][1], [RFC 4825][2]), and both are human and machine-readable. Neither one is absolutely superior to the other, as each is better suited for different use cases. + +### XML Advantages + +There are several advantages that XML has over JSON. One of the biggest differences between the two is that in XML you can put metadata into the tags in the form of attributes. With JSON, the programmer could accomplish the same goal that metadata achieves by making the entity an object and adding the attributes as members of the object. However, the way XML does it may often be preferable, given the slightly misleading nature of turning something into an object that is not one in the client program. For example, if your C++ program sends an int via JSON and needs metadata to be sent along with it, you would have to make it an object, with one name/value pair for the actual value of the int, and more name/value pairs for each attribute. The program that receives the JSON would read it as an object, when in fact it is not one. While this is a viable solution, it defies one of JSON’s key advantages: “JSON's structures look like conventional programming language structures. No restructuring is necessary.”[2] + +Although I will argue later that this can also be a drawback of XML, its mechanism to resolve name conflicts, prefixes, gives it power that JSON does not have. With prefixes, the programmer has the ability to name two different kinds of entities the same thing.[1] This would be advantageous in situations where the different entities should have the same name in the client program, perhaps if they are used in entirely different scopes. + +Another advantage of XML is that most browsers render it in a highly readable and organized way. The tree structure of XML lends itself well to this formatting, and allows for browsers to let users to naturally collapse individual tree elements. This feature would be particularly useful in debugging. + +One of the most significant advantages that XML has over JSON is its ability to communicate mixed content, i.e. strings that contain structured markup. In order to handle this with XML, the programmer need only put the marked-up text within a child tag of the parent in which it belongs. Similar to the metadata situation, since JSON only contains data, there is no such simple way to indicate markup. It would again require storing metadata as data, which could be considered an abuse of the format. + +### JSON Advantages + +JSON has several advantages as well. One of the most obvious of these is that JSON is significantly less verbose than XML, because XML necessitates opening and closing tags (or in some cases less verbose self-closing tags), and JSON uses name/value pairs, concisely delineated by “{“ and “}” for objects, “[“ and “]” for arrays, “,” to separate pairs, and “:” to separate name from value. Even when zipped (using gzip), JSON is still smaller and it takes less time to zip it.[6] As determined by Sumaray and Makki as well as Nurseitov, Paulson, Reynolds, and Izurieta in their experimental findings, JSON outperforms XML in a number of ways. First, naturally following from its conciseness, JSON files that contain the same information as their XML counterparts are almost always significantly smaller, which leads to faster transmission and processing. Second, difference in size aside, both groups found that JSON was serialized and deserialized drastically faster than XML.[3][4] Third, the latter study determined that JSON processing outdoes XML in CPU resource utilization. They found that JSON used less total resources, more user CPU, and less system CPU. The experiment used RedHat machines, and RedHat claims that higher user CPU usage is preferable.[3] Unsurprisingly, the Sumaray and Makki study determined that JSON performance is superior to XML on mobile devices too.[4] This makes sense, given that JSON uses less resources, and mobile devices are less powerful than desktop machines. + +Yet another advantage that JSON has over XML is that its representation of objects and arrays allows for direct mapping onto the corresponding data structures in the host language, such as objects, records, structs, dictionaries, hash tables, keyed lists, and associative arrays for objects, and arrays, vectors, lists, and sequences for arrays.[2] Although it is perfectly possible to represent these structures in XML, it is only as a function of the parsing, and it takes more code to serialize and deserialize properly. It also would not always be obvious to the reader of arbitrary XML what tags represent an object and what tags represent an array, especially because nested tags can just as easily be structured markup instead. The curly braces and brackets of JSON definitively show the structure of the data. However, this advantage does come with the caveat explained above, that the JSON can inaccurately represent the data if the need arises to send metadata. + +Although XML supports namespaces and prefixes, JSON’s handling of name collisions is less verbose than prefixes, and arguably feels more natural with the program using it; in JSON, each object is its own namespace, so names may be repeated as long as they are in different scopes. This may be preferable, as in most programming languages members of different objects can have the same name, because they are distinguished by the names of the objects to which they belong. + +Perhaps the most significant advantage that JSON has over XML is that JSON is a subset of JavaScript, so code to parse and package it fits very naturally into JavaScript code. This seems highly beneficial for JavaScript programs, but does not directly benefit any programs that use languages other than JavaScript. However, this drawback has been largely overcome, as currently the JSON website lists over 175 tools for 64 different programming languages that exist to integrate JSON processing. While I cannot speak to the quality of most of these tools, it is clear that the developer community has embraced JSON and has made it simple to use in many different platforms. + +### Purposes + +Simply put, XML’s purpose is document markup. This is decidedly not a purpose of JSON, so XML should be used whenever this is what needs to be done. It accomplishes this purpose by giving semantic meaning to text through its tree-like structure and ability to represent mixed content. Data structures can be represented in XML, but that is not its purpose. + +JSON’s purpose is structured data interchange. It serves this purpose by directly representing objects, arrays, numbers, strings, and booleans. Its purpose is distinctly not document markup. As described above, JSON does not have a natural way to represent mixed content. + +### Software + +The following major public APIs uses XML only: Amazon Product Advertising API. + +The following major APIs use JSON only: Facebook Graph API, Google Maps API, Twitter API, AccuWeather API, Pinterest API, Reddit API, Foursquare API. + +The following major APIs use both XML and JSON: Google Cloud Storage, Linkedin API, Flickr API + +Of the top 10 most popular APIs according to Programmable Web[9], along with a couple more popular ones, only one supports XML and not JSON. Several support both, and several support only JSON. Among developer APIs for modern and popular websites, JSON clearly seems to be preferred. This also indicates that more app developers that use these APIs prefer JSON. This is likely a result of its reputation as the faster and leaner of the two. Furthermore, most of these APIs communicate data rather than documents, so JSON would be more appropriate. For example, Facebook is mainly concerned with communicating data about users and posts, Google Maps deals in coordinates and information about entities on their maps, and AccuWeather just sends weather data. Overall, it is impossible to say whether JSON or XML is currently used more in APIs, but the trend is certainly swinging towards JSON.[10][11] + +The following major desktop software uses XML only: Microsoft Word, Apache OpenOffice, LibreOffice. + +It makes sense for software that is mainly concerned with document creation, manipulation, and storage to use XML rather than JSON. Also, all three of these programs support mixed content, which JSON does not do well. For example, if a user is typing up an essay in Microsoft Word, they may put different font, size, color, positioning, and styling on different blocks of text. XML naturally represents these properties with nested tags and attributes. + +The following major databases support XML: IBM DB2, Microsoft SQL Server, Oracle Database, PostgresSQL, BaseX, eXistDB, MarkLogic, MySQL. + +The following major databases support JSON: MongoDB, CouchDB, eXistDB, Elastisearch, BaseX, MarkLogic, OrientDB, Oracle Database, PostgresSQL, Riak. + +For a long time, SQL and the relational database model dominated the market. Corporate giants like Oracle and Microsoft have always marketed such databases. However, in the last decade, there has been a major rise in popularity of NoSQL databases. As this has coincided with the rise of JSON, most NoSQL databases support JSON, and some, such as MongoDB, CouchDB, and Riak use JSON to store their data. These databases have two important qualities that make them better suited for modern websites: they are generally more scalable than relational SQL databases, and they are designed to the core to run in the Web.[10] Since JSON is more lightweight and a subset of JavaScript, it suits NoSQL databases well, and helps facilitate these two qualities. In addition, many older databases have added support for JSON, such as Oracle Database and PostgresSQL. Conversion between XML and JSON is a hassle, so naturally, as more developers use JSON for their apps, more database companies have incentive to support it.[7] + +### Future + +One of the most heavily anticipated changes in the Internet is the “Internet of Things”, i.e. the addition to the Internet of non-computer devices such as watches, thermostats, televisions, refrigerators, etc. This movement is well underway, and is expected to explode in the near future, as predictions for the number of devices in the Internet of Things in 2020 range from about 26 billion to 200 billion.[12][13][13] Almost all of these devices are smaller and less powerful than laptop and desktop computers. Many of them only run embedded systems. Thus, when they have the need to exchange data with other entities in the Web, the lighter and faster JSON would naturally be preferable to XML.[10] Also, with the recent rapid rise of JSON use in the Web relative to XML, new devices may benefit more from speaking JSON. This highlights an example of Metcalf’s Law; whether XML or JSON or something entirely new becomes the most popular format in the Web, newly added devices and all existing devices will benefit much more if the newly added devices speak the most popular language. + +With the creation and recent rapid increase in popularity of Node.js, a server-side JavaScript framework, along with NoSQL databases like MongoDB, full-stack JavaScript development has become a reality. This bodes well for the future of JSON, as with these new apps, JSON is spoken at every level of the stack, which generally makes the apps very fast and lightweight. This is a desirable trait for any app, so this trend towards full-stack JavaScript is not likely to die out anytime soon.[10] + +Another existing trend in the world of app development is toward REST and away from SOAP.[11][15][16] Both XML and JSON can be used with REST, but SOAP exclusively uses XML. + +The given trends indicate that JSON will continue to dominate the Web, and XML use will continue to decrease. This should not be overblown, however, because XML is still very heavily used in the Web, and it is the only option for apps that use SOAP. Given the widespread migration from SOAP to REST, the rise of NoSQL databases and full-stack JavaScript, and the far superior performance of JSON, I believe that JSON will soon be much more widely used than XML in the Web. There seem to be very few applications where XML is the better choice. + +### References + +1. [XML Tutorial](http://www.w3schools.com/xml/default.asp) +2. [Introducing JSON](http://www.json.org/) +3. [Comparison of JSON and XML Data Interchange Formats: A Case Study](http://www.cs.montana.edu/izurieta/pubs/caine2009.pdf) +4. [A comparison of data serialization formats for optimal efficiency on a mobile platform](http://dl.acm.org/citation.cfm?id=2184810) +5. [JSON vs. XML: The Debate](http://ajaxian.com/archives/json-vs-xml-the-debate) +6. [JSON vs. XML: Some hard numbers about verbosity](http://www.codeproject.com/Articles/604720/JSON-vs-XML-Some-hard-numbers-about-verbosity) +7. [How JSON sparked NoSQL -- and will return to the RDBMS fold](http://www.infoworld.com/article/2608293/nosql/how-json-sparked-nosql----and-will-return-to-the-rdbms-fold.html) +8. [Did You Say "JSON Support" in Oracle 12.1.0.2?](https://blogs.oracle.com/OTN-DBA-DEV-Watercooler/entry/did_you_say_json_support) +9. [Most Popular APIs: At Least One Will Surprise You](http://www.programmableweb.com/news/most-popular-apis-least-one-will-surprise-you/2014/01/23) +10. [Why JSON will continue to push XML out of the picture](https://www.centurylinkcloud.com/blog/post/why-json-will-continue-to-push-xml-out-of-the-picture/) +11. [Thousands of APIs Paint a Bright Future for the Web](http://www.webmonkey.com/2011/03/thousand-of-apis-paint-a-bright-future-for-the-web/) +12. [A Simple Explanation Of 'The Internet Of Things’](http://www.forbes.com/sites/jacobmorgan/2014/05/13/simple-explanation-internet-things-that-anyone-can-understand/) +13. [Proofpoint Uncovers Internet of Things (IoT) Cyberattack](http://www.proofpoint.com/about-us/press-releases/01162014.php) +14. [The Internet of Things: New Threats Emerge in a Connected World](http://www.symantec.com/connect/blogs/internet-things-new-threats-emerge-connected-world) +15. [3,000 Web APIs: Trends From A Quickly Growing Directory](http://www.programmableweb.com/news/3000-web-apis-trends-quickly-growing-directory/2011/03/08) +16. [How REST replaced SOAP on the Web: What it means to you](http://www.infoq.com/articles/rest-soap) + + +-------------------------------------------------------------------------------- + +via: https://www.cs.tufts.edu/comp/150IDS/final_papers/tstras01.1/FinalReport/FinalReport.html#xml-advantages + +作者：[TOM STRASSNER][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]: tomstrassner@gmail.com +[b]: https://github.com/lujun9972 +[1]: https://tools.ietf.org/html/rfc7159 +[2]: https://tools.ietf.org/html/rfc4825 diff --git a/sources/talk/20180419 5 guiding principles you should know before you design a microservice.md b/sources/talk/20180419 5 guiding principles you should know before you design a microservice.md deleted file mode 100644 index fae228867e..0000000000 --- a/sources/talk/20180419 5 guiding principles you should know before you design a microservice.md +++ /dev/null @@ -1,158 +0,0 @@ -translated by lixinyuxx -5 guiding principles you should know before you design a microservice -====== - -![](https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/BIZ_OpenInnovation.png?itok=l29msbql) -One of the biggest challenges for teams starting off with microservices is adhering to the Goldilocks Principle: Not too big, not too small, and not too tightly coupled. Part of this challenge arises from confusion about what, exactly, constitutes a well-designed microservice. - -Dozens of CTOs shared their experiences through interviews, and those conversations illuminated five characteristics of well-designed microservices. This article will help guide teams as they design microservices. (For more information, check out the upcoming book [Microservices for Startups][1]). This article will briefly touch on microservice boundaries and arbitrary "rules" to avoid before diving into the five characteristics to guide your design of microservices. - -### Microservice boundaries - -One of the [core benefits of developing new systems with microservices][2] is that the architecture allows developers to build and modify individual components independently—but problems can arise when it comes to minimizing the number of callbacks between each API. The solution, according to Chris McFadden, VP of engineering at [SparkPost][3] , is to apply the appropriate service boundaries. - -With respect to boundaries, in contrast to the sometimes difficult-to-grasp and abstract concept of domain-driven design (DDD)—a framework for microservices—this article focuses on practical principles for creating well-defined microservice boundaries with some of our industry's top CTOs. - -### Avoid arbitrary "rules" - -If you read enough advice about designing and creating a microservice, you're bound to come across some of the "rules" below. Although it's tempting to use them as guideposts for creating microservices, adhesion to these arbitrary rules is not a principled way to determine thoughtful boundaries for microservices. - -#### "A microservice should have X lines of code" - -Let's get one thing straight: There are no limitations on how many lines of code there are in a microservice. A microservice doesn't suddenly become a monolith just because you write a few lines of extra code. The key is ensuring there is high cohesion for the code within a service (more on this later). - -#### "Turn each function into a microservice" - -If a function computes something based on three input values and returns a result, is it a good candidate for a microservice? Should it be a separately deployable application of its own? This really depends on what the function is and how it serves to the entire system. Turning each function into a microservice simply might not make sense in your context. - -Other arbitrary rules include those that don't take into account your entire context, such as the team's experience, DevOps capacity, what the service is doing, and availability needs of the data. - -### 5 characteristics of a well-designed service - -If you've read about microservices, you've no doubt come across advice on what makes a well-designed service. Simply put, high cohesion and loose coupling. There are [many][4] [articles][5] on these concepts to review if you're not familiar with them. And while they offer sound advice, these concepts are quite abstract. Below, based on conversations with experienced CTOs, are key characteristics to keep in mind when creating well-designed microservices. - -#### #1: It doesn't share database tables with another service - -In the early days of SparkPost, Chris McFadden and his team had to solve a problem that every SaaS business faces: They needed to provide basic services like authentication, account management, and billing. - -To tackle this, they created two microservices: a Users API and an Accounts API. The Users API would handle user accounts, API keys, and authentication, while the Accounts API would handle all of the billing-related logic. A very logical separation—but before long, they spotted a problem. - -"We had one service that was called the User API, and we had another one called the Account API. The problem was that they were actually having several calls back and forth between them. So you would do something in accounts and have a call and endpoint in users or vice versa," McFadden explained. - -The two services were too tightly coupled. - -When it comes to designing a microservice, it's a red flag if you have multiple services referencing the same table, as it likely means your DB is a source of coupling. - -It is really about how the service relates to the data, which is exactly what Oleksiy Kovrin, head of [Swiftype SRE, Elastic][6], told me. "One of the main foundational principles we use when developing new services is that they should not cross database boundaries. Each service should rely on its own set of underlying data stores. This allows us to centralize access controls, audit logging, caching logic, etc.," he said. - -Kovyrin went on to explain that if a subset of your database tables "have no or very little connections to the rest of the dataset, it is a strong signal that component could be isolated into a separate API or a separate service." - -Darby Frey, co-founder of [Lead Honestly][7], echoed this sentiment: "Each service should have its own tables [and] should never share database tables." - -#### #2: It has a minimal amount of database tables - -The ideal size of a microservice is small enough, but no smaller. And the same goes for the number of database tables per service. - -Steven Czerwinski, head of engineering, [Scaylr][8], explained during an interview that the sweet spot for Scaylr is "one or two database tables for a service." - -SparkPost's Chris McFadden agreed: "We have a suppression microservices, and it handles, keeps track of, millions and billions of entries around suppressions, but it's all very focused just around suppression, so there's really only one or two tables there. The same goes for other services like webhooks." - -#### #3: It's thoughtfully stateful or stateless - -When designing your microservice, you need to ask yourself whether it requires access to a database or whether it's going to be a stateless service processing terabytes of data like emails or logs. - -Julien Lemoine, CTO of [Algolia][9], explained, "We define the boundaries of a service by defining its input and output. Sometimes a service is a network API, but it can also be a process consuming files and producing records in a database (this is the case of our log-processing service)." - -Be clear about statefulness up front and it will lead to a better-designed service. - -#### #4: Its data availability needs are accounted for - -When designing a microservice, keep in mind what services will rely on this new service and the system-wide impact if that data becomes unavailable. Taking that into account allows you to properly design data backup and recovery systems for this service - -Steven Czerwinski mentioned that at Scaylr, critical customer row space mapping data is replicated and separated in different ways due to its importance. - -In contrast, he added, "The per shard information, that's in its own little partition. It sucks if it goes down because that portion of the customer population is not going to have their logs available, but it's only impacting 5 percent of the customers rather than 100 percent of the customers." - -#### #5: It's a single source of truth - -Design a service to be the single source of truth for something in your system - -For example, when you order something from an e-commerce site, an order ID is generated. This order ID can be used by other services to query an order service for complete information about the order. Using the [publish/subscribe pattern][10], the data that is passed around between services should be the order ID, not the attributes/information of the order itself. Only the order service has complete information and is the single source of truth for a given order. - -### Considerations for larger teams - -Keeping in mind the five considerations listed above, larger teams should be aware of the impacts of their organizational structure on microservice boundaries. - -For larger organizations, where entire teams can be dedicated to owning a service, organizational consideration comes into play when determining service boundaries. And there are two considerations to consider: **independent release schedule** and **different uptime importance**. - -"The most successful implementation of microservices we've seen is either based on a software design principle like domain-driven design, for example, and service-oriented architecture, or the ones that reflect an organizational approach," said Khash Sajadi, CEO of [Cloud66.][11] - -"So [for the] payments team," Sajadi continued, "they have the payment service or credit card validation service, and that's the service they provide to the outside world. So it's not necessarily anything about software. It's mostly about the business unit [that] provides one more service to the outside world." - -### The two-pizza principle - -Amazon is a perfect example of a large organization with multiple teams. As mentioned in an article published in [API Evangelist][12], Jeff Bezos issued a mandate to all employees informing them that every team within the company had to communicate via API. Anyone who didn't would be fired. - -This way, all the data and functionality was exposed through the interface. Bezos also managed to get every team to decouple, define what their resources are, and make them available through the API. Amazon was building a system from the ground up. This allows every team within the company to become a partner of one another. - -I spoke to Travis Reeder, CTO of [Iron.io][13], about Bezos' internal initiative. - -"Jeff Bezos mandated that all teams had to build API's to communicate with other teams," Reeder said. "He's also the guy who came up with the 'two-pizza' rule: A team shouldn't be larger than what two pizzas can feed. - -"I think the same could apply here: Whatever a small team can develop, manage, and be productive with. If it starts to get unwieldy or starts to slow down, it's probably getting too big," Reeder told me. - -### Final considerations: Is your service the right size and properly defined? - -During the testing and implementation phase of your microservice system, there are indicators to keep in mind. - -#### Indicator #1: Is there over-reliance between services? - -If two services are constantly calling back to one another, then that's a strong indication of coupling and a signal that they might be better off combined into one service. - -Going back to Chris McFadden's example where he had two API services, accounts, and users that were constantly communicating with one another, McFadden came up an idea to merge the services and decided to call it the Accuser's API. This turned out to be a fruitful strategy. - -"What we started doing was eliminating these links [which were the] internal API calls between them," McFadden told me. "It's helped simplify the code." - -#### Indicator #2: Does the overhead of setting up the service outweigh the benefit of having the service be independent? - -Darby Frey explained, "Every app needs to have its logs aggregated somewhere and needs to be monitored. You need to set up alerting for it. You need to have standard operating procedures and run books for when things break. You have to manage SSH access to that thing. There's a huge foundation of things that have to exist in order for an app to just run." - -### Key takeaways - -Designing microservices can often feel more like an art than a science. For engineers, that may not sit well. There's lots of general advice out there, but at times it can be a bit too abstract. Let's recap the five specific characteristics to look for when designing your next set of microservices: - - 1. It doesn't share database tables with another service - 2. It has a minimal amount of database tables - 3. It's thoughtfully stateful or stateless - 4. Its data availability needs are accounted for - 5. It's a single source of truth - - - -Next time you're designing a set of microservices and determining service boundaries, referring back to these principles should make the task easier. - --------------------------------------------------------------------------------- - -via: https://opensource.com/article/18/4/guide-design-microservices - -作者：[Jake Lumetta][a] -选题：[lujun9972](https://github.com/lujun9972) -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]:https://opensource.com/users/jakelumetta -[1]:https://buttercms.com/books/microservices-for-startups/ -[2]:https://buttercms.com/books/microservices-for-startups/should-you-always-start-with-a-monolith -[3]:https://www.sparkpost.com/ -[4]:https://thebojan.ninja/2015/04/08/high-cohesion-loose-coupling/ -[5]:https://en.wikipedia.org/wiki/Single_responsibility_principle -[6]:https://www.elastic.co/solutions/site-search -[7]:https://leadhonestly.com/ -[8]:https://www.scalyr.com/ -[9]:https://www.algolia.com/ -[10]:https://en.wikipedia.org/wiki/Publish%E2%80%93subscribe_pattern -[11]:https://www.cloud66.com/ -[12]:https://apievangelist.com/2012/01/12/the-secret-to-amazons-success-internal-apis/ -[13]:https://www.iron.io/ diff --git a/sources/talk/20180919 5 ways DevSecOps changes security.md b/sources/talk/20180919 5 ways DevSecOps changes security.md index 28e4b90eec..aef3780fdb 100644 --- a/sources/talk/20180919 5 ways DevSecOps changes security.md +++ b/sources/talk/20180919 5 ways DevSecOps changes security.md @@ -1,3 +1,5 @@ + translating by hopefully2333 + 5 ways DevSecOps changes security ====== diff --git a/sources/talk/20181029 How I organize my knowledge as a Software Engineer.md b/sources/talk/20181029 How I organize my knowledge as a Software Engineer.md deleted file mode 100644 index 73a46af506..0000000000 --- a/sources/talk/20181029 How I organize my knowledge as a Software Engineer.md +++ /dev/null @@ -1,111 +0,0 @@ -怎样如软件工程师一样组织知识 -========== - -总体上说，软件开发和技术是以非常快的速度发展的领域，所以持续学习是必不可少的。在互联网上花几分钟找一下，在 Twitter、媒体、RSS 订阅、Hacker News 和其它专业网站和社区等地方，就可以从文章、案例研究、教程、代码片段、新应用程序和信息中找到大量有用的信息。 - -保存和组织所有这些信息可能是一项艰巨的任务。在这篇文章中，我将介绍一些我用来组织信息的工具。 - -我认为在知识管理方面非常重要的一点就是避免锁定在特定平台。我使用的所有工具都允许以标准格式（如 Markdown 和 HTML）导出数据。 - -请注意，我的流程并不完美，我一直在寻找新工具和方法来优化它。每个人都不同，所以对我有用的东西可能不适合你。 - - -### 用 NotionHQ 做知识库 - -对我来说，知识管理的基本部分是拥有某种个人知识库或维基。这是一个你可以以有组织的方式保存链接、书签、备注等的地方。 - -我使用 [NotionHQ][7] 做这件事。我使用它来记录各种主题，包括资源列表，如通过编程语言分组的优秀的库或教程，为有趣的博客文章和教程添加书签等等，不仅与软件开发有关，而且与我的个人生活有关。 - -我真正喜欢 NotionHQ 的是，创建新内容是如此简单。你可以使用 Markdown 编写它并将其组织为树状。 - -这是我的“开发”工作区的顶级页面： - -[![Image](https://res.cloudinary.com/practicaldev/image/fetch/s--uMbaRUtu--/c_limit%2Cf_auto%2Cfl_progressive%2Cq_auto%2Cw_880/http://i.imgur.com/kRnuvMV.png)][8] - -NotionHQ 有一些很棒的其他功能，如集成了电子表格/数据库和任务板。 - -如果您想认真使用 NotionHQ，您将需要订阅付费个人计划，因为免费计划有所限制。我觉得它物有所值。NotionHQ 允许将整个工作区导出为 Markdown 文件。导出功能存在一些重要问题，例如丢失页面层次结构，希望 Notion 团队可以改进这一点。 - -作为一个免费的替代方案，我可能会使用 [VuePress][9] 或 [GitBook][10] 来托管我自己的知识库。 - -### 用 Pocket 保存感兴趣的文章 - -[Pocket][11] 是我最喜欢的应用之一！使用 Pocket，您可以创建一个来自互联网上的文章的阅读列表。每当我看到一篇看起来很有趣的文章时，我都会使用 Chrome 扩展程序将其保存到 Pocket。稍后，我会阅读它，如果我发现它足够有用，我将使用 Pocket 的“存档”功能永久保存该文章并清理我的 Pocket 收件箱。 - -我尽量保持这个阅读清单足够小，并存档我已经处理过的信息。Pocket 允许您标记文章，以便以后更轻松地搜索特定主题的文章。 - -如果原始网站消失，您还可以在 Pocket 服务器中保存文章的副本，但是您需要 Pocket Premium 订阅计划。 - -Pocket 还具有“发现”功能，根据您保存的文章推荐类似的文章。这是找到可以阅读的新内容的好方法。 - -### 用 SnippetStore 做代码片段管理 - -从 GitHub 到 Stack Overflow 的答案，到博客文章，经常能找到一些你想要保存备用的好代码片段。它可能是一些不错的算法实现、一个有用的脚本或如何在某种语言中执行某种操作的示例。 - -我尝试了很多应用程序，从简单的 GitHub Gists 到 [Boostnote][12]，直到我发现 [SnippetStore][13]。 - -SnippetStore 是一个开源的代码片段管理应用。SnippetStore 与其他产品的区别在于其简单性。您可以按语言或标签整理片段，并且可以拥有多个文件片段。它不完美，但是可以用。例如，Boostnote 具有更多功能，但我更喜欢 SnippetStore 组织内容的简单方法。 - -对于我每天使用的缩写和片段，我更喜欢使用我的编辑器 / IDE 的代码片段功能，因为它更便于使用。我使用 SnippetStore 更像是作为编码示例的参考。 - -[Cacher][14] 也是一个有趣的选择，因为它与许多编辑器进行了集成，他有一个命令行工具，并使用 Gi​​tHub Gists 作为后端，但其专业计划为 6 美元/月，我觉这有点太贵。 - -### 用 DevHints 管理速查表 - -[Devhints][15] 是由 Rico Sta. Cruz 创建的一个速查表集合。它是开源的，是用 Jekyll 生成的，Jekyll 是最受欢迎的静态站点生成器之一。 - -这些速查表是用 Markdown 编写的，带有一些额外的格式化支持，例如支持列。 - -我非常喜欢其界面的外观，并且不像可以在 [Cheatography][16] 等网站上找到 PDF 或图像格式的速查表， Markdown 非常容易添加新内容并保持更新和进行版本控制。 - -因为它是开源，我创建了自己的分叉版本，删除了一些我不需要的速查表，并添加了更多。 - -我使用速查表作为如何使用某些库或编程语言或记住一些命令的参考。速查表的单个页面非常方便，例如，可以列出特定编程语言的所有基本语法。 - -我仍在尝试这个工具，但到目前为止它的工作很好。 - -### Diigo - -[Diigo][17] 允许您注释和突出显示部分网站。我在研究新东西时使用它来注释重要信息，或者从文章、Stack Overflow 答案或来自 Twitter 的鼓舞人心的引语中保存特定段落！;） - -* * * - -就这些了。某些工具的功能方面可能存在一些重叠，但正如我在开始时所说的那样，这是一个不断演进的工作流程，因为我一直在尝试和寻找改进和提高工作效率的方法。 - -你呢？是如何组织你的知识的？请随时在下面发表评论。 - -谢谢你的阅读。 - ------------------------------------------------------------------------- - -作者简介：Bruno Paz，Web 工程师，专精 #PHP 和 @Symfony 框架。热心于新技术。喜欢运动，@FCPorto 的粉丝！ - --------------------------------------------------------------------------------- - -via: https://dev.to/brpaz/how-do-i-organize-my-knowledge-as-a-software-engineer-4387 - -作者：[Bruno Paz][a] -选题：[oska874](https://github.com/oska874) -译者：[wxy](https://github.com/wxy) -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]:http://brunopaz.net/ -[1]:https://dev.to/brpaz -[2]:http://twitter.com/brunopaz88 -[3]:http://github.com/brpaz -[4]:https://dev.to/t/knowledge -[5]:https://dev.to/t/learning -[6]:https://dev.to/t/development -[7]:https://www.notion.so/ -[8]:https://res.cloudinary.com/practicaldev/image/fetch/s--uMbaRUtu--/c_limit%2Cf_auto%2Cfl_progressive%2Cq_auto%2Cw_880/http://i.imgur.com/kRnuvMV.png -[9]:https://vuepress.vuejs.org/ -[10]:https://www.gitbook.com/?t=1 -[11]:https://getpocket.com/ -[12]:https://boostnote.io/ -[13]:https://github.com/ZeroX-DG/SnippetStore -[14]:https://www.cacher.io/ -[15]:https://devhints.io/ -[16]:https://cheatography.com/ -[17]:https://www.diigo.com/index diff --git a/sources/talk/20181212 5 resolutions for open source project maintainers.md b/sources/talk/20181212 5 resolutions for open source project maintainers.md deleted file mode 100644 index 8004b05745..0000000000 --- a/sources/talk/20181212 5 resolutions for open source project maintainers.md +++ /dev/null @@ -1,64 +0,0 @@ -[#]: collector: (lujun9972) -[#]: translator: (bestony) -[#]: reviewer: ( ) -[#]: publisher: ( ) -[#]: url: ( ) -[#]: subject: (5 resolutions for open source project maintainers) -[#]: via: (https://opensource.com/article/18/12/resolutions-open-source-project-maintainers) -[#]: author: (Ben Cotton https://opensource.com/users/bcotton) - -5 resolutions for open source project maintainers -====== -No matter how you say it, good communication is essential to strong open source communities. -![](https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/spark_sparkler_fire_new_year_idea.png?itok=rnyMpVP8) - -I'm generally not big on New Year's resolutions. I have no problem with self-improvement, of course, but I tend to anchor around other parts of the calendar. Even so, there's something about taking down this year's free calendar and replacing it with next year's that inspires some introspection. - -In 2017, I resolved to not share articles on social media until I'd read them. I've kept to that pretty well, and I'd like to think it has made me a better citizen of the internet. For 2019, I'm thinking about resolutions to make me a better open source software maintainer. - -Here are some resolutions I'll try to stick to on the projects where I'm a maintainer or co-maintainer. - -### 1\. Include a code of conduct - -Jono Bacon included "not enforcing the code of conduct" in his article "[7 mistakes you're probably making][1]." Of course, to enforce a code of conduct, you must first have a code of conduct. I plan on defaulting to the [Contributor Covenant][2], but you can use whatever you like. As with licenses, it's probably best to use one that's already written instead of writing your own. But the important thing is to find something that defines how you want your community to behave, whatever that looks like. Once it's written down and enforced, people can decide for themselves if it looks like the kind of community they want to be a part of. - -### 2\. Make the license clear and specific - -You know what really stinks? Unclear licenses. "This software is licensed under the GPL" with no further text doesn't tell me much. Which version of the [GPL][3]? Do I get to pick? For non-code portions of a project, "licensed under a Creative Commons license" is even worse. I love the [Creative Commons licenses][4], but there are several different licenses with significantly different rights and obligations. So, I will make it very clear which variant and version of a license applies to my projects. I will include the full text of the license in the repo and a concise note in the other files. - -Sort of related to this is using an [OSI][5]-approved license. It's tempting to come up with a new license that says exactly what you want it to say, but good luck if you ever need to enforce it. Will it hold up? Will the people using your project understand it? - -### 3\. Triage bug reports and questions quickly - -Few things in technology scale as poorly as open source maintainers. Even on small projects, it can be hard to find the time to answer every question and fix every bug. But that doesn't mean I can't at least acknowledge the person. It doesn't have to be a multi-paragraph reply. Even just labeling the GitHub issue shows that I saw it. Maybe I'll get to it right away. Maybe I'll get to it a year later. But it's important for the community to see that, yes, there is still someone here. - -### 4\. Don't push features or bug fixes without accompanying documentation - -For as much as my open source contributions over the years have revolved around documentation, my projects don't reflect the importance I put on it. There aren't many commits I can push that don't require some form of documentation. New features should obviously be documented at (or before!) the time they're committed. But even bug fixes should get an entry in the release notes. If nothing else, a push is a good opportunity to also make a commit to improving the docs. - -### 5\. Make it clear when I'm abandoning a project - -I'm really bad at saying "no" to things. I told the editors I'd write one or two articles for [Opensource.com][6] and here I am almost 60 articles later. Oops. But at some point, the things that once held my interests no longer do. Maybe the project is unnecessary because its functionality got absorbed into a larger project. Maybe I'm just tired of it. But it's unfair to the community (and potentially dangerous, as the recent [event-stream malware injection][7] showed) to leave a project in limbo. Maintainers have the right to walk away whenever and for whatever reason, but it should be clear that they have. - -Whether you're an open source maintainer or contributor, if you know other resolutions project maintainers should make, please share them in the comments. - --------------------------------------------------------------------------------- - -via: https://opensource.com/article/18/12/resolutions-open-source-project-maintainers - -作者：[Ben Cotton][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/bcotton -[b]: https://github.com/lujun9972 -[1]: https://opensource.com/article/17/8/mistakes-open-source-avoid -[2]: https://www.contributor-covenant.org/ -[3]: https://opensource.org/licenses/gpl-license -[4]: https://creativecommons.org/share-your-work/licensing-types-examples/ -[5]: https://opensource.org/ -[6]: http://Opensource.com -[7]: https://arstechnica.com/information-technology/2018/11/hacker-backdoors-widely-used-open-source-software-to-steal-bitcoin/ diff --git a/sources/talk/20190108 Hacking math education with Python.md b/sources/talk/20190108 Hacking math education with Python.md new file mode 100644 index 0000000000..111b306c7a --- /dev/null +++ b/sources/talk/20190108 Hacking math education with Python.md @@ -0,0 +1,84 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Hacking math education with Python) +[#]: via: (https://opensource.com/article/19/1/hacking-math) +[#]: author: (Don Watkins https://opensource.com/users/don-watkins) + +Hacking math education with Python +====== +Teacher, programmer, and author Peter Farrell explains why teaching math with Python works better than the traditional approach. +![](https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/getting_started_with_python.png?itok=MFEKm3gl) + +Mathematics instruction has a bad reputation, especially with people (like me) who've had trouble with the traditional approach, which emphasizes rote memorization and theory that seems far removed from students' real world. + +While teaching a student who was baffled by his math lessons, [Peter Farrell][1], a Python developer and mathematics teacher, decided to try using Python to teach the boy the math concepts he was having trouble learning. + +Peter was inspired by the work of [Seymour Papert][2], the father of the Logo programming language, which lives on in Python's [Turtle module][3]. The Turtle metaphor hooked Peter on Python and using it to teach math, much like [I was drawn to Python][4]. + +Peter shares his approach in his new book, [Math Adventures with Python][5]: An Illustrated Guide to Exploring Math with Code. And, I recently interviewed him to learn more about it. + +**Don Watkins:** What is your background? + +**Peter Farrell:** I was a math teacher for eight years, and I tutored math for 10 years after that. When I was a teacher, I read Papert's [Mindstorms][6] and was inspired to introduce all my math classes to Logo and Turtles. + +**DW:** Why did you start using Python? + +**PF:** I was working with a homeschooled boy on a very dry, textbook-driven math curriculum, which at the time seemed like a curse to me. But I found ways to sneak in the Logo Turtles, and he was a programming fan, so he liked that. Once we got into functions and real programming, he asked if we could continue in Python. I didn't know any Python but it didn't seem that different from Logo, so I agreed. And I never looked back! + +I was also looking for a 3D graphics package I could use to model a solar system and lead students through making planets move and get pulled by the force of attraction between the bodies, according to Newton's formula. Many graphics packages required programming in C or something hard, but I found an excellent package called Visual Python that was very easy to use. I used [VPython][7] for years after that. + +So, I was introduced to Python in the context of working with a student on math. For some time after that, he was my programming tutor while I was his math tutor! + +**DW:** What got you interested in math? + +**PF:** I learned it the old-fashioned way: by hand, on paper and blackboards. I was good at manipulating symbols, so algebra was never a problem, and I liked drawing and graphing, so geometry and trig could be fun, too. I did some programming in BASIC and Fortran in college, but it never inspired me. Later on, programming inspired me greatly! I'm still tickled by the way programming makes easy work of the laborious stuff you have to do in math class, freeing you up to do the more fun of exploring, graphing, tweaking, and discovering. + +**DW:** What inspired you to consider your Python approach to math? + +**PF:** When I was teaching the homeschooled student, I was amazed at what we could do by writing a simple function and then calling it a bunch of times with different values using a loop. That would take a half an hour by hand, but the computer spit it out instantly! Then we could look for patterns (which is what a math student should be doing), express the pattern as a function, and extend it further. + +**DW:** How does your approach to teaching help students—especially those who struggle with math? How does it make math more relevant? + +**PF:** Students, especially high-schoolers, question the need to be doing all this calculating, graphing, and solving by hand in the 21st century, and I don't disagree with them. Learning to use Excel, for example, to crunch numbers should be seen as a basic necessity to work in an office. Learning to code, in any language, is becoming a very valuable skill to companies. So, there's a real-world appeal to me. + +But the idea of making art with code can revolutionize math class. Just putting a shape on a screen requires math—the position (x-y coordinates), the dimensions, and even the color are all numbers. If you want something to move or change, you'll need to use variables, and not the "guess what x equals" kind of variable. You'll vary the position using a variable or, more efficiently, using a vector. [This makes] math topics like vectors and matrices seen as helpful tools you can use, rather than required information you'll never use. + +Students who struggle with math might just be turned off to "school math," which is heavy on memorization and following rules and light on creativity and real applications. They might find they're actually good at math, just not the way it was taught in school. I've had parents see the cool graphics their kids have created with code and say, "I never knew that's what sines and cosines were used for!" + +**DW:** How do you see your approach to math and programming encouraging STEM in schools? + +**PF:** I love the idea of combining previously separated topics into an idea like STEM or STEAM! Unfortunately for us math folks, the "M" is very often neglected. I see lots of fun projects being done in STEM labs, even by very young children, and they're obviously getting an education in technology, engineering, and science. But I see precious little math material in the projects. STEM/[mechatronics][8] teacher extraordinaire Ken Hawthorn and I are creating projects to try to remedy that. + +Hopefully, my book helps encourage students, girls and boys, to get creative with technology, real and virtual. There are a lot of beautiful graphics in the book, which I hope will inspire people to go through the coding adventure and make them. All the software I use ([Python Processing][9]) is available for free and can be easily installed, or is already installed, on the Raspberry Pi. Entry into the STEM world should not be cost-prohibitive to schools or individuals. + +**DW:** What would you like to share with other math teachers? + +**PF:** If the math establishment is really serious about teaching students the standards they have agreed upon, like numerical reasoning, logic, analysis, modeling, geometry, interpreting data, and so on, they're going to have to admit that coding can help with every single one of those goals. My approach was born, as I said before, from just trying to enrich a dry, traditional approach, and I think any teacher can do that. They just need somebody who can show them how to do everything they're already doing, just using code to automate the laborious stuff. + +My graphics-heavy approach is made possible by the availability of free graphics software. Folks might need to be shown where to find these packages and how to get started. But a math teacher can soon be leading students through solving problems using 21st-century technology and visualizing progress or results and finding more patterns to pursue. + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/19/1/hacking-math + +作者：[Don Watkins][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://opensource.com/users/don-watkins +[b]: https://github.com/lujun9972 +[1]: https://twitter.com/hackingmath +[2]: https://en.wikipedia.org/wiki/Seymour_Papert +[3]: https://en.wikipedia.org/wiki/Turtle_graphics +[4]: https://opensource.com/life/15/8/python-turtle-graphics +[5]: https://nostarch.com/mathadventures +[6]: https://en.wikipedia.org/wiki/Mindstorms_(book) +[7]: http://vpython.org/ +[8]: https://en.wikipedia.org/wiki/Mechatronics +[9]: https://processing.org/ diff --git a/sources/talk/20190108 NSA to Open Source its Reverse Engineering Tool GHIDRA.md b/sources/talk/20190108 NSA to Open Source its Reverse Engineering Tool GHIDRA.md new file mode 100644 index 0000000000..78922f9525 --- /dev/null +++ b/sources/talk/20190108 NSA to Open Source its Reverse Engineering Tool GHIDRA.md @@ -0,0 +1,89 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (NSA to Open Source its Reverse Engineering Tool GHIDRA) +[#]: via: (https://itsfoss.com/nsa-ghidra-open-source) +[#]: author: (Ankush Das https://itsfoss.com/author/ankush/) + +NSA to Open Source its Reverse Engineering Tool GHIDRA +====== + +GHIDRA – NSA’s reverse engineering tool is getting ready for a free public release this March at the [RSA Conference 2019][1] to be held in San Francisco. + +The National Security Agency (NSA) did not officially announce this – however – a senior NSA advisor, Robert Joyce’s [session description][2] on the official RSA conference website revealed about it before any official statement or announcement. + +Here’s what it mentioned: + +![][3] +Image Credits: [Twitter][4] + +In case the text in the image isn’t properly visible, let me quote the description here: + +> NSA has developed a software reverse engineering framework known as GHIDRA, which will be demonstrated for the first time at RSAC 2019. An interactive GUI capability enables reverse engineers to leverage an integrated set of features that run on a variety of platforms including Windows, Mac OS, and Linux and supports a variety of processor instruction sets. The GHISDRA platform includes all the features expected in high-end commercial tools, with new and expanded functionality NSA uniquely developed. and will be released for free public use at RSA. + +### What is GHIDRA? + +GHIDRA is a software reverse engineering framework developed by [NSA][5] that is in use by the agency for more than a decade. + +Basically, a software reverse engineering tool helps to dig up the source code of a proprietary program which further gives you the ability to detect virus threats or potential bugs. You should read how [reverse engineering][6] works to know more. + +The tool is is written in Java and quite a few people compared it to high-end commercial reverse engineering tools available like [IDA][7]. + +A [Reddit thread][8] involves more detailed discussion where you will find some ex-employees giving good amount of details before the availability of the tool. + +![NSA open source][9] + +### GHIDRA was a secret tool, how do we know about it? + +The existence of the tool was uncovered in a series of leaks by [WikiLeaks][10] as part of [Vault 7 documents of CIA][11]. + +### Is it going to be open source? + +We do think that the reverse engineering tool to be released could be made open source. Even though there is no official confirmation mentioning “open source” – but a lot of people do believe that NSA is definitely targeting the open source community to help improve their tool while also reducing their effort to maintain this tool. + +This way the tool can remain free and the open source community can help improve GHIDRA as well. + +You can also check out the existing [Vault 7 document at WikiLeaks][12] to come up with your prediction. + +### Is NSA doing a good job here? + +The reverse engineering tool is going to be available for Windows, Linux, and Mac OS for free. + +Of course, we care about the Linux platform here – which could be a very good option for people who do not want to or cannot afford a thousand dollar license for a reverse engineering tool with the best-in-class features. + +### Wrapping Up + +If GHIDRA becomes open source and is available for free, it would definitely help a lot of researchers and students and on the other side – the competitors will be forced to adjust their pricing. + +What are your thoughts about it? Is it a good thing? What do you think about the tool going open sources Let us know what you think in the comments below. + +![][13] + +-------------------------------------------------------------------------------- + +via: https://itsfoss.com/nsa-ghidra-open-source + +作者：[Ankush Das][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://itsfoss.com/author/ankush/ +[b]: https://github.com/lujun9972 +[1]: https://www.rsaconference.com/events/us19 +[2]: https://www.rsaconference.com/events/us19/agenda/sessions/16608-come-get-your-free-nsa-reverse-engineering-tool +[3]: https://i1.wp.com/itsfoss.com/wp-content/uploads/2019/01/come-get-your-free-nsa.jpg?fit=800%2C337&ssl=1 +[4]: https://twitter.com/0xffff0800/status/1080909700701405184 +[5]: http://nsa.gov +[6]: https://en.wikipedia.org/wiki/Reverse_engineering +[7]: https://en.wikipedia.org/wiki/Interactive_Disassembler +[8]: https://www.reddit.com/r/ReverseEngineering/comments/ace2m3/come_get_your_free_nsa_reverse_engineering_tool/ +[9]: https://i0.wp.com/itsfoss.com/wp-content/uploads/2019/01/nsa-open-source.jpeg?resize=800%2C450&ssl=1 +[10]: https://www.wikileaks.org/ +[11]: https://en.wikipedia.org/wiki/Vault_7 +[12]: https://wikileaks.org/ciav7p1/cms/page_9536070.html +[13]: https://i0.wp.com/itsfoss.com/wp-content/uploads/2019/01/nsa-open-source.jpeg?fit=800%2C450&ssl=1 diff --git a/sources/talk/20190110 Toyota Motors and its Linux Journey.md b/sources/talk/20190110 Toyota Motors and its Linux Journey.md new file mode 100644 index 0000000000..1d76ffe0b6 --- /dev/null +++ b/sources/talk/20190110 Toyota Motors and its Linux Journey.md @@ -0,0 +1,64 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Toyota Motors and its Linux Journey) +[#]: via: (https://itsfoss.com/toyota-motors-linux-journey) +[#]: author: (Abhishek Prakash https://itsfoss.com/author/abhishek/) + +Toyota Motors and its Linux Journey +====== + +**This is a community submission from It’s FOSS reader Malcolm Dean.** + +I spoke with Brian R Lyons of TMNA Toyota Motor Corp North America about the implementation of Linux in Toyota and Lexus infotainment systems. I came to find out there is an Automotive Grade Linux (AGL) being used by several autmobile manufacturers. + +I put together a short article comprising of my discussion with Brian about Toyota and its tryst with Linux. I hope that Linux enthusiasts will like this quick little chat. + +All [Toyota vehicles and Lexus vehicles are going to use Automotive Grade Linux][1] (AGL) majorly for the infotainment system. This is instrumental in Toyota Motor Corp because as per Mr. Lyons “As a technology leader, Toyota realized that adopting open source development methodology is the best way to keep up with the rapid pace of new technologies”. + +Toyota among other automotive companies thought, going with a Linux based operating system might be cheaper and quicker when it comes to updates, and upgrades compared to using proprietary software. + +Wow! Finally Linux in a vehicle. I use Linux every day on my desktop; what a great way to expand the use of this awesome software to a completely different industry. + +I was curious when Toyota decided to use the [Automotive Grade Linux][2] (AGL). According to Mr. Lyons, it goes back to 2011. + +> “Toyota has been an active member and contributor to AGL since its launch more than five years ago, collaborating with other OEMs, Tier 1s and suppliers to develop a robust, Linux-based platform with increased security and capabilities” + +![Toyota Infotainment][3] + +In 2011, [Toyota joined the Linux Foundation][4] and started discussions about IVI (In-Vehicle Infotainment) software with other car OEMs and software companies. As a result, in 2012, Automotive Grade Linux working group was formed in the Linux Foundation. + +What Toyota did at first in AGL group was to take “code first” approach as normal as in the open source domains, and then start the conversation about the initial direction by specifying requirement specifications which had been discussed among car OEMs, IVI Tier-1 companies, software companies, and so on. + +Toyota had already realized that sharing the software code among Tier1 companies was going to essential at the time when it joined the Linux Foundation. This was because the cost of maintaining such a huge software was very costly and was no longer differentiation by Tier1 companies. Toyota and its Tier1 supplier companies wanted to spend more resources n new functions and new user experiences rather than maintaining conventional code all by themselves. + +This is a huge thing as automotive companies have gone in together to further their cooperation. Many companies have adopted this after finding proprietary software to be expensive. + +Today, AGL is used for all Toyota and Lexus vehicles and is used in all markets where vehicles are sold. + +As someone who has sold cars for Lexus, I think this is a huge step forward. I and other sales associates had many customers who would come back to speak with a technology specialist to learn about the full capabilities of their infotainment system. + +I see this as a huge step forward for the Linux community, and users. The operating system we use on a daily basis is being put to use right in front of us albeit in a modified form but is there none-the-less. + +Where does this lead? Hopefully a better user-friendly and less glitchy experience for consumers. + + +-------------------------------------------------------------------------------- + +via: https://itsfoss.com/toyota-motors-linux-journey + +作者：[Abhishek Prakash][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://itsfoss.com/author/abhishek/ +[b]: https://github.com/lujun9972 +[1]: https://www.linuxfoundation.org/press-release/2018/01/automotive-grade-linux-hits-road-globally-toyota-amazon-alexa-joins-agl-support-voice-recognition/ +[2]: https://www.automotivelinux.org/ +[3]: https://i2.wp.com/itsfoss.com/wp-content/uploads/2019/01/toyota-interiors.jpg?resize=800%2C450&ssl=1 +[4]: https://www.linuxfoundation.org/press-release/2011/07/toyota-joins-linux-foundation/ diff --git a/sources/talk/20190111 What metrics matter- A guide for open source projects.md b/sources/talk/20190111 What metrics matter- A guide for open source projects.md new file mode 100644 index 0000000000..1438450a99 --- /dev/null +++ b/sources/talk/20190111 What metrics matter- A guide for open source projects.md @@ -0,0 +1,95 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (What metrics matter: A guide for open source projects) +[#]: via: (https://opensource.com/article/19/1/metrics-guide-open-source-projects) +[#]: author: (Gordon Haff https://opensource.com/users/ghaff) + +What metrics matter: A guide for open source projects +====== +5 principles for deciding what to measure. +![](https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/metrics_data_dashboard_system_computer_analytics.png?itok=oxAeIEI-) + +"Without data, you're just a person with an opinion." + +Those are the words of W. Edwards Deming, the champion of statistical process control, who was credited as one of the inspirations for what became known as the Japanese post-war economic miracle of 1950 to 1960. Ironically, Japanese manufacturers like Toyota were far more receptive to Deming’s ideas than General Motors and Ford were. + +Community management is certainly an art. It’s about mentoring. It’s about having difficult conversations with people who are hurting the community. It’s about negotiation and compromise. It’s about interacting with other communities. It’s about making connections. In the words of Red Hat’s Diane Mueller, it’s about "nurturing conversations." + +However, it’s also about metrics and data. + +Some have much in common with software development projects more broadly. Others are more specific to the management of the community itself. I think of deciding what to measure and how as adhering to five principles. + +### 1. Recognize that behaviors aren't independent of the measurements you choose to highlight. + +In 2008, Daniel Ariely published Predictably Irrational, one of a number of books written around that time that introduced behavioral psychology and behavioral economics to the general public. One memorable quote from that book is the following: “Human beings adjust behavior based on the metrics they’re held against. Anything you measure will impel a person to optimize his score on that metric. What you measure is what you’ll get. Period.” + +This shouldn’t be surprising. It’s a finding that’s been repeatedly confirmed by research. It should also be familiar to just about anyone with business experience. It’s certainly not news to anyone in sales management, for example. Base sales reps’ (or their managers’) bonuses solely on revenue, and they’ll try to discount whatever it takes to maximize revenue, even if it puts margin in the toilet. Conversely, want the sales force to push a new product line—which will probably take extra effort—but skip the spiffs? Probably not happening. + +And lest you think I’m unfairly picking on sales, this behavior is pervasive, all the way up to the CEO, as Ariely describes in a 2010 Harvard Business Review article: “CEOs care about stock value because that’s how we measure them. If we want to change what they care about, we should change what we measure.” + +Developers and other community members are not immune. + +### 2. You need to choose relevant metrics. + +There’s a lot of folk wisdom floating around about what’s relevant and important that’s not necessarily true. My colleague [Dave Neary offers an example from baseball][1]: “In the late '90s, the key measurements that were used to measure batter skill were RBI (runs batted in) and batting average (how often a player got on base with a hit, divided by the number of at-bats). The Oakland A’s were the first major league team to recruit based on a different measurement of player performance: on-base percentage. This measures how often they get to first base, regardless of how it happens.” + +Indeed, the whole revolution of sabermetrics in baseball and elsewhere, which was popularized in Michael Lewis’ Moneyball, often gets talked about in terms of introducing data in a field that historically was more about gut feel and personal experience. But it was also about taking a game that had actually always been fairly numbers-obsessed and coming up with new metrics based on mostly existing data to better measure player value. (The data revolution going on in sports today is more about collecting much more data through video and other means than was previously available.) + +### 3. Quantity may not lead to quality. + +As a corollary, collecting lots of tangential but easy-to-capture data isn’t better than just selecting a few measurements you’ve determined are genuinely useful. In a world where online behavior can be tracked with great granularity and displayed in colorful dashboards, it’s tempting to be distracted by sheer data volume, even when it doesn’t deliver any great insight into community health and trajectory. + +This may seem like an obvious point: Why measure something that isn’t relevant? In practice, metrics often get chosen because they’re easy to measure, not because they’re particularly useful. They tend to be more about inputs than outputs: The number of developers. The number of forum posts. The number of commits. Collectively, measures like this often get called vanity metrics. They’re ubiquitous, but most people involved with community management don’t think much of them. + +Number of downloads may be the worst of the bunch. It’s true that, at some level, they’re an indication of interest in a project. That’s something. But it’s sufficiently distant from actively using the project, much less engaging with the project deeply, that it’s hard to view downloads as a very useful number. + +Is there any harm in these vanity metrics? Yes, to the degree that you start thinking that they’re something to base action on. Probably more seriously, stakeholders like company management or industry observers can come to see them as meaningful indicators of project health. + +### 4. Understand what measurements really mean and how they relate to each other. + +Neary makes this point to caution against myopia. “In one project I worked on,” he says, ”some people were concerned about a recent spike in the number of bug reports coming in because it seemed like the project must have serious quality issues to resolve. However, when we looked at the numbers, it turned out that many of the bugs were coming in because a large company had recently started using the project. The increase in bug reports was actually a proxy for a big influx of new users, which was a good thing.” + +In practice, you often have to measure through proxies. This isn’t an inherent problem, but the further you get between what you want to measure and what you’re actually measuring, the harder it is to connect the dots. It’s fine to track progress in closing bugs, writing code, and adding new features. However, those don’t necessarily correlate with how happy users are or whether the project is doing a good job of working towards its long-term objectives, whatever those may be. + +### 5. Different measurements serve different purposes. + +Some measurements may be non-obvious but useful for tracking the success of a project and community relative to internal goals. Others may be better suited for a press release or other external consumption. For example, as a community manager, you may really care about the number of meetups, mentoring sessions, and virtual briefings your community has held over the past three months. But it’s the number of contributions and contributors that are more likely to grab the headlines. You probably care about those too. But maybe not as much, depending upon your current priorities. + +Still, other measurements may relate to the goals of any sponsoring organizations. The measurements most relevant for projects tied to commercial products are likely to be different from pure community efforts. + +Because communities differ and goals differ, it’s not possible to simply compile a metrics checklist, but here are some ideas to think about: + +Consider qualitative metrics in addition to quantitative ones. Conducting surveys and other studies can be time-consuming, especially if they’re rigorous enough to yield better-than-anecdotal data. It also requires rigor to construct studies so that they can be used to track changes over time. In other words, it’s a lot easier to measure quantitative contributor activity than it is to suss out if the community members are happier about their participation today than they were a year ago. However, given the importance of culture to the health of a community, measuring it in a systematic way can be a worthwhile exercise. + +Breadth of community, including how many are unaffiliated with commercial entities, is important for many projects. The greater the breadth, the greater the potential leverage of the open source development process. It can also be instructive to see how companies and individuals are contributing. Projects can be explicitly designed to better accommodate casual contributors. + +Are new contributors able to have an impact, or are they ignored? How long does it take for code contributions to get committed? How long does it take for a reported bug to be fixed or otherwise responded to? If they asked a question in a forum, did anyone answer them? In other words, are you letting contributors contribute? + +Advancement within the project is also an important metric. [Mikeal Rogers of the Node.js community][2] explains: “The shift that we made was to create a support system and an education system to take a user and turn them into a contributor, first at a very low level, and educate them to bring them into the committer pool and eventually into the maintainer pool. The end result of this is that we have a wide range of skill sets. Rather than trying to attract phenomenal developers, we’re creating new phenomenal developers.” + +Whatever metrics you choose, don’t forget why you made them metrics in the first place. I find a helpful question to ask is: “What am I going to do with this number?” If the answer is to just put it in a report or in a press release, that’s not a great answer. Metrics should be measurements that tell you either that you’re on the right path or that you need to take specific actions to course-correct. + +For this reason, Stormy Peters, who handles community leads at Red Hat, [argues for keeping it simple][3]. She writes, “It’s much better to have one or two key metrics than to worry about all the possible metrics. You can capture all the possible metrics, but as a project, you should focus on moving one. It’s also better to have a simple metric that correlates directly to something in the real world than a metric that is a complicated formula or ration between multiple things. As project members make decisions, you want them to be able to intuitively feel whether or not it will affect the project’s key metric in the right direction.” + +The article is adapted from [How Open Source Ate Software][4] by Gordon Haff (Apress 2018). + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/19/1/metrics-guide-open-source-projects + +作者：[Gordon Haff][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/ghaff +[b]: https://github.com/lujun9972 +[1]: https://community.redhat.com/blog/2014/07/when-metrics-go-wrong/ +[2]: https://opensource.com/article/17/3/nodejs-community-casual-contributors +[3]: https://medium.com/open-source-communities/3-important-things-to-consider-when-measuring-your-success-50e21ad82858 +[4]: https://www.apress.com/us/book/9781484238936 diff --git a/sources/talk/20190114 Remote Working Survival Guide.md b/sources/talk/20190114 Remote Working Survival Guide.md new file mode 100644 index 0000000000..42b151f4cb --- /dev/null +++ b/sources/talk/20190114 Remote Working Survival Guide.md @@ -0,0 +1,130 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Remote Working Survival Guide) +[#]: via: (https://www.jonobacon.com/2019/01/14/remote-working-survival/) +[#]: author: (Jono Bacon https://www.jonobacon.com/author/admin/) + +Remote Working Survival Guide +====== +![](https://www.jonobacon.com/wp-content/uploads/2019/01/5b5471d7eadb585ec8b8a0c3_featureimage-remotejob-1080x675.jpg) + +Remote working seems to be all the buzz. Apparently, [70% of professionals work from home at least once a week][1]. Similarly, [77% of people work more productively][2] and [68% of millennials would consider a company more if they offered remote working][3]. It seems to make sense: technology, connectivity, and culture seem to be setting the world up more and more for remote working. Oh, and home-brewed coffee is better than ever too. + +Now, I am going to write another piece for how companies should optimize for remote working (so make sure you [Join As a Member][4] to stay tuned — it is free). + +Today though I want to **share recommendations for how individuals can do remote working well themselves**. Whether you are a full-time remote worker or have the option of working from home a few days a week, this article should hopefully be helpful. + +Now, you need to know that **remote working is not a panacea**. Sure, it seems like hanging around at home in your jimjams, listening to your antisocial music, and sipping on buckets of coffee is perfect, but it isn’t for everyone. + +Some people need the structure of an office. Some people need the social element of an office. Some people need to get out the house. Some people lack the discipline to stay focused at home. Some people are avoiding the government coming and knocking on the door due to years of unpaid back taxes. + +**Remote working is like a muscle: it can bring enormous strength and capabilities IF you train and maintain it**. If you don’t, your results are going to vary. + +I have worked from home for the vast majority of my career. I love it. I am more productive, happier, and empowered when I work from home. I don’t dislike working in an office, and I enjoy the social element, but I am more in my “zone” when I work from home. I also love blisteringly heavy metal, which can pose a problem when the office don’t want to listen to [After The Burial][5]. + +![][6] +“Squirrel.” +[Credit][7] + +I have learned how I need to manage remote work, using the right balance of work routine, travel, and other elements, and here are some of my recommendations. Be sure to **share yours in the comments**. + +### 1\. You need discipline and routine (and to understand your “waves”) + +Remote work really is a muscle that needs to be trained. Just like building actual muscle, there needs to be a clear routine and a healthy dollop of discipline mixed in. + +Always get dressed (no jimjams). Set your start and end time for your day (I work 9am – 6pm most days). Choose your lunch break (mine is 12pm). Choose your morning ritual (mine is email followed by a full review of my client needs). Decide where your main workplace will be (mine is my home office). Decide when you will exercise each day (I do it at 5pm most days). + +**Design a realistic routine and do it for 66 days**. It takes this long to build a habit. Try not to deviate from the routine. The more you stick the routine, the less work it will seem further down the line. By the end of the 66 days it will feel natural and you won’t have to think about it. + +Here’s the deal though, we don’t live in a vacuum ([cleaner, or otherwise][8]). We all have waves. + +A wave is when you need a change of routine to mix things up. For example, in summertime I generally want more sunlight. I will often work outside in the garden. Near the holidays I get more distracted, so I need more structure in my day. Sometimes I just need more human contact, so I will work from coffee shops for a few weeks. Sometimes I just fancy working in the kitchen or on the couch. You need to learn your waves and listen to your body. **Build your habit first, and then modify it as you learn your waves**. + +### 2\. Set expectations with your management and colleagues + +Not everyone knows how to do remote working, and if your company is less familiar with remote working, you especially need to set expectations with colleagues. + +This can be pretty simple: **when you have designed your routine, communicate it clearly to your management and team**. Let them know how they can get hold of you, how to contact you in an emergency, and how you will be collaborating while at home. + +The communication component here is critical. There are some remote workers who are scared to leave their computer for fear that someone will send them a message while they are away (and they are worried people may think they are just eating Cheetos and watching Netflix). + +You need time away. You need to eat lunch without one eye on your computer. You are not a 911 emergency responder. **Set expectations that sometimes you may not be immediately responsive, but you will get back to them as soon as possible**. + +Similarly, set expectations on your general availability. For example, I set expectations with clients that I generally work from 9am – 6pm every day. Sure, if a client needs something urgently, I am more than happy to respond outside of those hours, but as a general rule I am usually working between those hours. This is necessary for a balanced life. + +### 3\. Distractions are your enemy and they need managing + +We all get distracted. It is human nature. It could be your young kid getting home and wanting to play Rescue Bots. It could be checking Facebook, Instagram, or Twitter to ensure you don’t miss any unwanted political opinions or photos of people’s lunches. It could be that there is something else going on your life that is taking your attention (such as an upcoming wedding, event, or big trip.) + +**You need to learn what distracts you and how to manage it**. For example, I know I get distracted by my email and Twitter. I check it religiously and every check gets me out of the zone of what I am working on. I also get distracted by grabbing coffee and water, which then may turn into a snack and a YouTube video. + +![][9] +My nemesis for distractions. + +The digital distractions have a simple solution: **lock them out**. Close down the tabs until you complete what you are doing. I do this all the time with big chunks of work: I lock out the distractions until I am done. It requires discipline, but all of this does. + +The human elements are tougher. If you have a family you need to make it clear that when you are work, you need to be generally left alone. This is why a home office is so important: you need to set boundaries that mum or dad is working. Come in if there is emergency, but otherwise they need to be left alone. + +There are all kinds of opportunities for locking these distractions out. Put your phone on silent. Set yourself as away. Move to a different room (or building) where the distraction isn’t there. Again, be honest in what distracts you and manage it. If you don’t, you will always be at their mercy. + +### 4\. Relationships need in-person attention + +Some roles are more attuned to remote working than others. For example, I have seen great work from engineering, quality assurance, support, security, and other teams (typically more focused on digital collaboration). Other teams such as design or marketing often struggle more in remote environments (as they are often more tactile.) + +With any team though, having strong relationship is critical, and in-person discussion, collaboration, and socializing is essential to this. So many of our senses (such as body language) are removed in a digital environment, and these play a key role in how we build trust and relationships. + +![][10] +Rockets also help. + +This is especially important if (a) you are new a company and need to build these relationships, (b) are new to a role and need to build relationships with your team, or (c) are in a leadership position where building buy-in and engagement is a key part of your job. + +**The solution? A sensible mix of remote and in-person time.** If your company is nearby, work from home part of the week and at the office part of the week. If your company is further a away, schedule regular trips to the office (and set expectations with your management that you need this). For example, when I worked at XPRIZE I flew to LA every few weeks for a few days. When I worked at Canonical (who were based in London), we had sprints every three months. + +### 5\. Stay focused, but cut yourself some slack + +The crux of everything in this article is about building a capability, and developing a remote working muscle. This is as simple as building a routine, sticking to it, and having an honest view of your “waves” and distractions and how to manage them. + +I see the world in a fairly specific way: **everything we do has the opportunity to be refined and improved**. For example, I have been public speaking now for over 15 years, but I am always discovering new ways to improve, and new mistakes to fix (speaking of which, see my [10 Ways To Up Your Public Speaking Game][11].) + +There is a thrill in the discovery of new ways to get better, and to see every stumbling block and mistake as an “aha!” moment to kick ass in new and different ways. It is no different with remote working: look for patterns that help to unlock ways in which you can make your remote working time more efficient, more comfortable, and more fun. + +![][12] +Get these books. They are fantastic for personal development. +See my [$150 Personal Development Kit][13] article + +…but don’t go crazy over it. There are some people who obsesses every minute of their day about how to get better. They beat themselves up constantly for “not doing well enough”, “not getting more done”, and not meeting their internal unrealistic view of perfection. + +We are humans. We are animals, and we are not robots. Always strive to improve, but be realistic that not everything will be perfect. You are going to have some off-days or off-weeks. You are going to struggle at times with stress and burnout. You are going to handle a situation poorly remotely that would have been easier in the office. Learn from these moments but don’t obsess over them. Life is too damn short. + +**What are your tips, tricks, and recommendations? How do you manage remote working? What is missing from my recommendations? Share them in the comments box!** + + +-------------------------------------------------------------------------------- + +via: https://www.jonobacon.com/2019/01/14/remote-working-survival/ + +作者：[Jono Bacon][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.jonobacon.com/author/admin/ +[b]: https://github.com/lujun9972 +[1]: https://www.cnbc.com/2018/05/30/70-percent-of-people-globally-work-remotely-at-least-once-a-week-iwg-study.html +[2]: http://www.cosocloud.com/press-release/connectsolutions-survey-shows-working-remotely-benefits-employers-and-employees +[3]: https://www.aftercollege.com/cf/2015-annual-survey +[4]: https://www.jonobacon.com/join/ +[5]: https://www.facebook.com/aftertheburial/ +[6]: https://www.jonobacon.com/wp-content/uploads/2019/01/aftertheburial2.jpg +[7]: https://skullsnbones.com/burial-live-photos-vans-warped-tour-denver-co/ +[8]: https://www.youtube.com/watch?v=wK1PNNEKZBY +[9]: https://www.jonobacon.com/wp-content/uploads/2019/01/IMG_20190114_102429-1024x768.jpg +[10]: https://www.jonobacon.com/wp-content/uploads/2019/01/15381733956_3325670fda_k-1024x576.jpg +[11]: https://www.jonobacon.com/2018/12/11/10-ways-to-up-your-public-speaking-game/ +[12]: https://www.jonobacon.com/wp-content/uploads/2019/01/DwVBxhjX4AgtJgV-1024x532.jpg +[13]: https://www.jonobacon.com/2017/11/13/150-dollar-personal-development-kit/ diff --git a/sources/talk/20190114 You (probably) don-t need Kubernetes.md b/sources/talk/20190114 You (probably) don-t need Kubernetes.md new file mode 100644 index 0000000000..5526f48f48 --- /dev/null +++ b/sources/talk/20190114 You (probably) don-t need Kubernetes.md @@ -0,0 +1,76 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (You (probably) don't need Kubernetes) +[#]: via: (https://arp242.net/weblog/dont-need-k8s.html) +[#]: author: (Martin Tournoij https://arp242.net/) + +You (probably) don't need Kubernetes +====== + +This may perhaps be an unpopular opinion, but the overwhelming majority of companies are probably better off not using k8s. + +You know those old “Hello world according to programmer skill” jokes that start with `printf("hello, world\n")` for a junior programmer and end with some convoluted Java OOP design pattern solution for senior software architect engineer? This is kind of like that. + +* Junior sysops + `./binary` +* Experienced sysops + `./binary` on EC2. +* devops + Self-deployed CI pipeline to run `./binary` on EC2. +* Senior cloud orchestration engineer + k8s orchestrated self-deployed CI pipeline to run `./binary` on E2C platform. + + + +¯\\_(ツ)_/¯ + +That doesn’t mean that Kubernetes or any of these things are bad per se, just as Java or OOP aren’t bad per se, but rather that they’re horribly misapplied in many cases, just as using several Java OOP design patterns are horribly misapplied to a hello world program. For most companies the sysops requirements are fundamentally not very complex, and applying k8s to them makes litle sense. + +Complexity creates work by its very nature, and I’m skeptical that using k8s is a time-saver for most users. It’s like spending a day on a script to automate some 10-minute task that you do once a month. That’s not a good time investment (especially since the chances are you’ll have to invest further time in the future by expanding or debugging that script at some point). + +Your deployments probably should be automated – lest you [end up like Knightmare][1] – but k8s can often be replaced by a simple shell script. + +In our own company the sysops team spent a lot of time setting up k8s. They also had to spend a lot of time on updating to a newer version a while ago (1.6 ➙ 1.8). And the result is something no one really understands without really diving in to k8s, and even then it’s hard (those YAML files, yikes!) + +Before I could debug and fix deploy issues myself. Now that’s a lot harder. I understand the basic concepts, but that’s not all that useful when actually debugging practical issues. I don’t deal with k8s often enough to justify learning this. + +That k8s is really hard is not a novel insight, which is why there are a host of “k8s made easy” solutions out there. The idea of adding another layer on top of k8s to “make it easier” strikes me as, ehh, unwise. It’s not like that complexity disappears; you’ve just hidden it. + +I have said this many times before: when determining if something is “easy” then my prime concern is not how easy something is to write, but how easy something is to debug when things fail. Wrapping k8s will not make things easier to debug, quite the opposite: it will make it even harder. + +There is a famous Blaise Pascal quote: + +> All human evil comes from a single cause, man’s inability to sit still in a room. + +k8s – and to lesser extent, Docker – seem to be an example of that. A lot of people seem lost in the excitement of the moment and are “k8s al the things!”, just as some people were lost in the excitement when Java OOP was new, so everything has to be converted from the “old” way to the “new” ones, even though the “old” ways still worked fine. + +Sometimes the IT industry is pretty silly. + +Or to summarize this post [with a Tweet][2]: + +> 2014 - We must adopt #microservices to solve all problems with monoliths +> 2016 - We must adopt #docker to solve all problems with microservices +> 2018 - We must adopt #kubernetes to solve all problems with docker + +You can mail me at [martin@arp242.net][3] or [create a GitHub issue][4] for feedback, questions, etc. + +-------------------------------------------------------------------------------- + +via: https://arp242.net/weblog/dont-need-k8s.html + +作者：[Martin Tournoij][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://arp242.net/ +[b]: https://github.com/lujun9972 +[1]: https://dougseven.com/2014/04/17/knightmare-a-devops-cautionary-tale/ +[2]: https://twitter.com/sahrizv/status/1018184792611827712 +[3]: mailto:martin@arp242.net +[4]: https://github.com/Carpetsmoker/arp242.net/issues/new diff --git a/sources/talk/20190115 The Art of Unix Programming, reformatted.md b/sources/talk/20190115 The Art of Unix Programming, reformatted.md new file mode 100644 index 0000000000..73ffb4c955 --- /dev/null +++ b/sources/talk/20190115 The Art of Unix Programming, reformatted.md @@ -0,0 +1,54 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (The Art of Unix Programming, reformatted) +[#]: via: (https://arp242.net/weblog/the-art-of-unix-programming.html) +[#]: author: (Martin Tournoij https://arp242.net/) + +The Art of Unix Programming, reformatted +====== + +tl;dr: I reformatted Eric S. Raymond’s The Art of Unix Programming for readability; [read it here][1]. + +I recently wanted to look up a quote for an article I was writing, and I was fairly sure I had read it in The Art of Unix Programming. Eric S. Raymond (esr) has [kindly published it online][2], but it’s difficult to search as it’s distributed over many different pages, and the formatting is not exactly conducive for readability. + +I `wget --mirror`’d it to my drive, and started out with a simple [script][3] to join everything to a single page, but eventually ended up rewriting a lot of the HTML from crappy 2003 docbook-generated tagsoup to more modern standards, and I slapped on some CSS to make it more readable. + +The results are fairly nice, and it should work well in any version of any browser (I haven’t tested Internet Explorer and Edge, lacking access to a Windows computer, but I’m reasonably confident it should work without issues; if not, see the bottom of this page on how to get in touch). + +The HTML could be simplified further (so rms can read it too), but dealing with 360k lines of ill-formatted HTML is not exactly my idea of fun, so this will have to do for now. + +The entire page is self-contained. You can save it to your laptop or mobile phone and read it on a plane or whatnot. + +Why spend so much work on an IT book from 2003? I think a substantial part of the book still applies very much today, for all programmers (not just Unix programmers). For example the [Basics of the Unix Philosophy][4] was good advice in 1972, is still good advice in 2019, and will continue to be good advice well in to the future. + +Other parts have aged less gracefully; for example “since 2000, practice has been moving toward use of XML-DocBook as a documentation interchange format” doesn’t really represent the current state of things, and the [Data File Metaformats][5] section mentions XML and INI, but not JSON or YAML (as they weren’t invented until after the book was written) + +I find this adds, rather than detracts. It makes for an interesting window in to past. The downside is that the uninitiated will have a bit of a hard time distinguishing between the good and outdated parts; as a rule of thumb: if it talks about abstract concepts, it probably still applies today. If it talks about specific software, it may be outdated. + +I toyed with the idea of updating or annotating the text, but the license doesn’t allow derivative works, so that’s not going to happen. Perhaps I’ll email esr and ask nicely. Another project, for another weekend :-) + +You can mail me at [martin@arp242.net][6] or [create a GitHub issue][7] for feedback, questions, etc. + +-------------------------------------------------------------------------------- + +via: https://arp242.net/weblog/the-art-of-unix-programming.html + +作者：[Martin Tournoij][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://arp242.net/ +[b]: https://github.com/lujun9972 +[1]: https://arp242.net/the-art-of-unix-programming/ +[2]: http://catb.org/~esr/writings/taoup/html/ +[3]: https://arp242.net/the-art-of-unix-programming/fix-taoup.py +[4]: https://arp242.net/the-art-of-unix-programming#ch01s06 +[5]: https://arp242.net/the-art-of-unix-programming/#ch05s02 +[6]: mailto:martin@arp242.net +[7]: https://github.com/Carpetsmoker/arp242.net/issues/new diff --git a/sources/talk/20191110 What is DevSecOps.md b/sources/talk/20191110 What is DevSecOps.md new file mode 100644 index 0000000000..007f8f0c76 --- /dev/null +++ b/sources/talk/20191110 What is DevSecOps.md @@ -0,0 +1,85 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (What is DevSecOps?) +[#]: via: (https://opensource.com/article/19/1/what-devsecops) +[#]: author: (Brett Hunoldt https://opensource.com/users/bretthunoldtcom) + +What is DevSecOps? +====== +The journey to DevSecOps begins with empowerment, enablement, and education. Here's how to get started. +![](https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/devop.png?itok=Yicb2nnZ) + +> “DevSecOps enables organizations to deliver inherently secure software at DevOps speed.” -Stefan Streichsbier + +DevSecOps as a practice or an art form is an evolution on the concept of DevOps. To better understand DevSecOps, you should first have an understanding of what DevOps means. + +DevOps was born from merging the practices of development and operations, removing the silos, aligning the focus, and improving efficiency and performance of both the teams and the product. A new synergy was formed, with DevOps focused on building products and services that are easy to maintain and that automate typical operations functions. + +Security is a common silo in many organizations. Security’s core focus is protecting the organization, and sometimes this means creating barriers or policies that slow down the execution of new services or products to ensure that everything is well understood and done safely and that nothing introduces unnecessary risk to the organization. + +**[[Download the Getting started with DevSecOps guide]][1]** + +Because of the distinct nature of the security silo and the friction it can introduce, development and operations sometimes bypass or work around security to meet their objectives. At some firms, the silo creates an expectation that security is entirely the responsibility of the security team and it is up to them to figure out what security defects or issues may be introduced as a result of a product. + +DevSecOps looks at merging the security discipline within DevOps. By enhancing or building security into the developer and/or operational role, or including a security role within the product engineering team, security naturally finds itself in the product by design. + +This allows companies to release new products and updates more quickly and with full confidence that security is embedded into the product. + +### Where does rugged software fit into DevSecOps? + +Building rugged software is more an aspect of the DevOps culture than a distinct practice, and it complements and enhances a DevSecOps practice. Think of a rugged product as something that has been battle-hardened through experimentation or experience. + +It’s important to note that rugged software is not necessarily 100% secure (although it may have been at some point in time). However, it has been designed to handle most of what is thrown at it. + +The key tenets of a rugged software practice are fostering competition, experimentation, controlled failure, and cooperation. + +### How do you get started in DevSecOps? + +Gettings started with DevSecOps involves shifting security requirements and execution to the earliest possible stage in the development process. It ultimately creates a shift in culture where security becomes everyone’s responsibility, not only the security team’s. + +You may have heard teams talking about a "shift left." If you flatten the development pipeline into a horizontal line to include the key stages of the product evolution—from initiation to design, building, testing, and finally to operating—the goal of a security is to be involved as early as possible. This allows the risks to be better evaluated, socialized, and mitigated by design. The "shift-left" mentality is about moving this engagement far left in this pipeline. + +This journey begins with three key elements: + + * empowerment + * enablement + * education + + + +Empowerment, in my view, is about releasing control and allowing teams to make independent decisions without fear of failure or repercussion (within reason). The only caveat in this process is that information is critical to making informed decisions (more on that below). + +To achieve empowerment, business and executive support (which can be created through internal sales, presentations, and establishing metrics to show the return on this investment) is critical to break down the historic barriers and siloed teams. Integrating security into the development and operations teams and increasing both communication and transparency can help you begin the journey to DevSecOps. + +This integration and mobilization allows teams to focus on a single outcome: Building a product for which they share responsibility and collaborate on development and security in a reliable way. This will take you most of the way towards empowerment. It places the shared responsibility for the product with the teams building it and ensures that any part of the product can be taken apart and maintain its security. + +Enablement involves placing the right tools and resources in the hands of the teams. It’s about creating a culture of knowledge-sharing through forums, wikis, and informal gatherings. + +Creating a culture that focuses on automation and the concept that repetitive tasks should be coded will likely reduce operational overhead and strengthen security. This scenario is about more than providing knowledge; it is about making this knowledge highly accessible through multiple channels and mediums (which are enabled through tools) so that it can be consumed and shared in whatever way teams or individuals prefer. One medium might work best when team members are coding and another when they are on the road. Make the tools accessible and simple and let the team play with them. + +Different DevSecOp teams will have different preferences, so allow them to be independent whenever possible. This is a delicate balancing exercise because you do want economies of scale and the ability to share among products. Collaboration and involvement in the selection and renewal of these tools will help lower the barriers of adoption. + +Finally, and perhaps most importantly, DevSecOps is about training and awareness building. Meetups, social gatherings, or formal presentations within the organization are great ways for peers to teach and share their learnings. Sometimes these highlight shared challenges, concerns, or risks others may not have considered. Sharing and teaching are also effective ways to learn and to mentor teams. + +In my experience, each organization's culture is unique, so you can’t take a “one-size-fits-all” approach. Reach out to your teams and find out what tools they want to use. Test different forums and gatherings and see what works best for your culture. Seek feedback and ask the teams what is working, what they like, and why. Adapt and learn, be positive, and never stop trying, and you’ll almost always succeed. + +[Download the Getting started with DevSecOps guide][1] + + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/19/1/what-devsecops + +作者：[Brett Hunoldt][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/bretthunoldtcom +[b]: https://github.com/lujun9972 +[1]: https://opensource.com/downloads/devsecops diff --git a/sources/tech/20120201 Computer Laboratory - Raspberry Pi- Lesson 1 OK01.md b/sources/tech/20120201 Computer Laboratory - Raspberry Pi- Lesson 1 OK01.md deleted file mode 100644 index f16c290504..0000000000 --- a/sources/tech/20120201 Computer Laboratory - Raspberry Pi- Lesson 1 OK01.md +++ /dev/null @@ -1,232 +0,0 @@ -[#]: collector: (lujun9972) -[#]: translator: (qhwdw) -[#]: reviewer: ( ) -[#]: publisher: ( ) -[#]: url: ( ) -[#]: subject: (Computer Laboratory – Raspberry Pi: Lesson 1 OK01) -[#]: via: (https://www.cl.cam.ac.uk/projects/raspberrypi/tutorials/os/ok01.html) -[#]: author: (Robert Mullins http://www.cl.cam.ac.uk/~rdm34) - -Computer Laboratory – Raspberry Pi: Lesson 1 OK01 -====== - -The OK01 lesson contains an explanation about how to get started and teaches how to enable the 'OK' or 'ACT' **LED** on the Raspberry Pi board near the RCA and USB ports. This light was originally labelled OK but has been renamed to ACT on the revision 2 Raspberry Pi boards. - -### 1 Getting Started - -I am assuming at this point that you have already visited the [Downloads][1] page, and got the necessary GNU Toolchain. Also on the downloads page is a file called OS Template. Please download this and extract its contents to a new directory. - -### 2 The Beginning - -``` -The '.s' file extension is commonly used for all forms of assembly code, it is up to us to remember this is ARMv6. -``` - -Now that you have extracted the template, create a new file in the 'source' directory called 'main.s'. This file will contain the code for this operating system. To be explicit, the folder structure should look like: - -``` -build/ - (empty) -source/ - main.s -kernel.ld -LICENSE -Makefile -``` - -Open 'main.s' in a text editor so that we can begin typing assembly code. The Raspberry Pi uses a variety of assembly code called ARMv6, so that is what we'll need to write in. - -Copy in these first commands. - -``` -.section .init -.globl _start -_start: -``` - -As it happens, none of these actually do anything on the Raspberry Pi, these are all instructions to the assembler. The assembler is the program that will translate between assembly code that we understand, and binary machine code that the Raspberry Pi understands. In Assembly Code, each line is a new command. The first line here tells the Assembler[1] where to put our code. The template I provided causes the code in the section called .init to be put at the start of the output. This is important, as we want to make sure we can control which code runs first. If we don't do this, the code in the alphabetically first file name will run first! The .section command simply tells the assembler which section to put the code in, from this point until the next .section or the end of the file. - -``` -In assembly code, you may skip lines, and put spaces before and after commands to aid readability. -``` - -The next two lines are there to stop a warning message and aren't all that important.[2] - -### 3 The First Line - -Now we're actually going to code something. In assembly code, the computer simply goes through the code, doing each instruction in order, unless told otherwise. Each instruction starts on a new line. - -Copy the following instruction. - -``` -ldr r0,=0x20200000 -``` - -``` -ldr reg,=val puts the number val into the register named reg. -``` - -That is our first command. It tells the processor to store the number 0x20200000 into the register r0. I shall need to answer two questions here, what is a register, and how is 0x20200000 a number? - -``` -A single register can store any integer between 0 and 4,294,967,295 inclusive on the Raspberry Pi, which might seem like a large amount of memory, but it is only 32 binary bits. -``` - -A register is a tiny piece of memory in the processor, which is where the processor stores the numbers it is working on right now. There are quite a few of these, many of which have a special meaning, which we will come to later. Importantly there are 13 (named r0,r1,r2,...,r9,r10,r11,r12) which are called General Purpose, and you can use them for whatever calculations you need to do. Since it's the first, I've used r0 in this example, but I could very well have used any of the others. As long as you're consistent, it doesn't matter. - -0x20200000 is indeed a number. However it is written in Hexadecimal notation. To learn more about hexadecimal expand the box below: -``` -Hexadecimal is an alternate system for writing numbers. You may only be aware of the decimal system for writing numbers in which we have 10 digits: 0,1,2,3,4,5,6,7,8 and 9. Hexadecimal is a system with 16 digits: 0,1,2,3,4,5,6,7,8,9,a,b,c,d,e and f. - -![567 is 5 hundreds, 6 tens and 7 units.][2] - -You may recall being taught how decimal numbers work in terms of place value. We say that the rightmost digits is the 'units' digits, the next one left is the 'tens' digit, the next is the 'hundreds' digit, and so on. What this actually meant is, the number is 100 × the value in the 'hundreds' digit, plus 10 × the value in the 'tens' digit, plus 1 × the value in the units digit. - -![567 is 5x10^2+6x10^1+7x10^0][3] - -More mathematically, we can now spot the pattern and say that the rightmost digit is the 100=1s digit, the next left is the 101=10s digit, the next is 102=100s digit, and so on. We have all agreed on the system that 0 is the lowest digit, 1 is the next and so on. But what if we used a different number instead of 10 in these powers? Hexadecimal is just the system in which we use 16 instead. - -![567 = 5x10^2+6x10^1+7x10^0 = 2x16^2+3x16^1+7x16^0][4] - -The mathematics to the right shows that the number 567 in decimal is equivalent to the number 237 in hexadecimal. Often when we need to be clear about what system we're using to write numbers in we put 10 for decimal and 16 for hexadecimal. Since it's difficult to write small numbers in assembly code, we use 0x instead to represent a number in hexadecimal notation. So 0x237 means 23716. - -So where do a,b,c,d,e and f come in? Well, in order to be able to write every number in hexadecimal, we need extra digits. For example 916 = 9×160 = 910, but 1016 = 1×161 + 1×160 = 1610. So if we just used 0,1,2,3,4,5,6,7,8 and 9 we would not be able to write 1010, 1110, 1210, 1310, 1410, 1510. So we introduce 6 new digits such that a16 = 1010, b16 = 1110, c16 = 1210, d16 = 1310, e16 = 1410, f16 = 1510 - -So, we now have another system for writing numbers. But why did we bother? Well, it turns out that since computers always work in binary, hexadecimal notation is very useful because every hexadecimal digit is exactly four binary digits long. This has the nice side effect that a lot of computer numbers are round numbers in hexadecimal, even though they're not in decimal. For example, in the assembly code just above I used the number 2020000016. If I had chose to write this in decimal it would have been 53896806410, which is much less memorable. - -To convert numbers from decimal to hexadecimal I find the following method easiest: - -![Conversion example][5] - - 1. Start with the decimal number, say 567. - 2. Divide by 16 and calculate the remainder. For example 567 ÷ 16 = 35 remainder 7. - 3. The remainder is the last digit of the answer in hexadecimal, in the example this is 7. - 4. Repeat steps 2 and 3 again with the result of the last division until the result is 0. For example 35 ÷ 16 = 2 remainder 3, so 3 is the next digit of the answer. 2 ÷ 16 = 0 remainder 2, so 2 is the next digit of the answer. - 5. Once the result of the division is 0, you can stop. The answer is just the remainders in the reverse order to which you got them, so 56710 = 23716. - - - -To convert hexadecimal numbers back to decimal, it is easiest to expand out the number, so 23716 = 2×162 + 3×161 +7 ×160 = 2×256 + 3×16 + 7×1 = 512 + 48 + 7 = 567. -``` - -So our first command is to put the number 2020000016 into r0. That doesn't sound like it would be much use, but it is. In computers, there are an awful lot of chunks of memory and devices. In order to access them all, we give each one an address. Much like a postal address or a web address this is just a means of identifying the location of the device or chunks of memory we want. Addresses in computers are just numbers, and so the number 2020000016 happens to be the address of the GPIO controller. This is just a design decision taken by the manufacturers, they could have used any other address (providing it didn't conflict with anything else). I know this address only because I looked it up in a manual[3], there is no particular system to the addresses (other than that they are all large round numbers in hexadecimal). - -### 4 Enabling Output - -![A diagram showing key parts of the GPIO controller.][6] - -Having read the manual, I know we're going to need to send two messages to the GPIO controller. We need to talk its language, but if we do, it will obligingly do what we want and turn on the OK LED. Fortunately, it is such a simple chip, that it only needs a few numbers in order to understand what to do. - -``` -mov r1,#1 -lsl r1,#18 -str r1,[r0,#4] -``` - -``` -mov reg,#val puts the number val into the register named reg. - -lsl reg,#val shifts the binary representation of the number in reg by val places to the left. - -str reg,[dest,#val] stores the number in reg at the address given by dest + val. -``` - -These commands enable output to the 16th GPIO pin. First we get a necessary value in r1, then send it to the GPIO controller. Since the first two instructions are just trying to get a value into r1, we could use another ldr command as before, but it will be useful to us later to be able to set any given GPIO pin, so it is better to deduce the value from a formula than write it straight in. The OK LED is wired to the 16th GPIO pin, and so we need to send a command to enable the 16th pin. - -The value in r1 is needed to enable the LED pin. The first line puts the number 110 into r1. The mov command is faster than the ldr command, because it does not involve a memory interaction, whereas ldr loads the value we want to put into the register from memory. However, mov can only be used to load certain values[4]. In ARM assembly code, almost every instruction begins with a three letter code. This is called the mnemonic, and is supposed to hint at what the operation does. mov is short for move and ldr is short for load register. mov moves the second argument #1 into the first r1. In general, # must be used to denote numbers, but we have already seen a counterexample to this. - -The second instruction is lsl or logical shift left. This means shift the binary representation for the first argument left by the second argument. In this case this will shift the binary representation of 110 (which is 12) left by 18 places (making it 10000000000000000002=26214410). - -If you are unfamiliar with binary, expand the box below: -``` -Just like hexadecimal binary is another way of writing numbers. In binary we only have 2 digits, 0 and 1. This is useful for computers because we can implement this in a circuit by saying that electricity flowing through the circuit means 1, and not means 0. This is how computers actually work and do maths. Despite only having 2 digits binary can still be used to represent every number, it just takes a lot longer. - -![567 in decimal = 1000110111 in binary][7] - -The image shows the binary representation of the number 56710 which is 10001101112. We use 2 to denote numbers written in binary. - -One of the quirks of binary that we make heavy use of in assembly code is the ease by which numbers can be multiplied or divided by powers of 2 (e.g. 1,2,4,8,16). Normally multiplications and divisions are tricky operations, however these special cases are very easy, and so are very important. - -![13*4 = 52, 1101*100=110100][8] - -Shifting a binary number left by **n** places is the same as multiplying the number by 2 **n**. So, if we want to multiply by 4, we just shift the number left 2 places. If we want to multiply by 256 we could shift it left by 8 places. If we wanted to multiply by a number like 12, we could instead multiply it by 8, then separately by 4 and add the results (N × 12 = N × (8 + 4) = N × 8 + N × 4). - -![53/16 = 3, 110100/10000=11][9] - -Shifting a binary number right by **n** places is the same as dividing the number by 2 **n**. The remainder of the division is the bits that were lost when shifted right. Unfortunately dividing by a binary number that is not an exact power of 2 is very difficult, and will be covered in [Lesson 9: Screen04][10]. - -![Binary Terminology][11] - -This diagram shows common terminology used with binary. A bit is a single binary digit. A nibble is 4 binary bits. A byte is 2 nibbles, or 8 bits. A half is half the size of a word, 2 bytes in this case. A word refers to the size of the registers on a processor, and so on the Raspberry Pi this is 4 bytes. The convention is to number the most significant bit of a word 31, and the least significant bit as 0. The top, or high bits refer to the most significant bits, and the low or bottom bits refer to the least significant. A kilobyte (KB) is 1000 bytes, a megabyte is 1000 KB. There is some confusion as to whether this should be 1000 or 1024 (a round number in binary). As such, the new international standard is that a KB is 1000 bytes, and a Kibibyte (KiB) is 1024 bytes. A Kb is 1000 bits, and a Kib is 1024 bits. - -The Raspberry Pi is little endian by default, meaning that loading a byte from an address you just wrote a word to will load the lowest byte of the word. -``` - -Once again, I only know that we need this value from reading the manual[3]. The manual says that there is a set of 24 bytes in the GPIO controller, which determine the settings of the GPIO pin. The first 4 relate to the first 10 GPIO pins, the second 4 relate to the next 10 and so on. There are 54 GPIO pins, so we need 6 sets of 4 bytes, which is 24 bytes in total. Within each 4 byte section, every 3 bits relates to a particular GPIO pin. Since we want the 16th GPIO pin, we need the second set of 4 bytes because we're dealing with pins 10-19, and we need the 6th set of 3 bits, which is where the number 18 (6×3) comes from in the code above. - -Finally the str 'store register' command stores the value in the first argument, r1 into the address computed from the expression afterwards. The expression can be a register, in this case r0, which we know to be the GPIO controller address, and another value to add to it, in this case #4. This means we add 4 to the GPIO controller address and write the value in r1 to that location. This happens to be the location of the second set of 4 bytes that I mentioned before, and so we send our first message to the GPIO controller, telling it to ready the 16th GPIO pin for output. - -### 5 A Sign Of Life - -Now that the LED is ready to turn on, we need to actually turn it on. This means sending a message to the GPIO controller to turn pin 16 off. Yes, turn it off. The chip manufacturers decided it made more sense[5] to have the LED turn on when the GPIO pin is off. Hardware engineers often seem to take these sorts of decisions, seemingly just to keep OS Developers on their toes. Consider yourself warned. - -``` -mov r1,#1 -lsl r1,#16 -str r1,[r0,#40] -``` - -Hopefully you should recognise all of the above commands, if not their values. The first puts a 1 into r1 as before. The second shifts the binary representation of this 1 left by 16 places. Since we want to turn pin 16 off, we need to have a 1 in the 16th bit of this next message (other values would work for other pins). Finally we write it out to the address which is 4010 added to the GPIO controller address, which happens to be the address to write to turn a pin off (28 would turn the pin on). - -### 6 Happily Ever After - -It might be tempting to finish now, but unfortunately the processor doesn't know we're done. In actuality, the processor never will stop. As long as it has power, it continues working. Thus, we need to give it a task to do forever more, or the Raspberry Pi will crash (not much of a problem in this example, the light is already on). - -``` -loop$: -b loop$ -``` - -``` -name: labels the next line name. - -b label causes the next line to be executed to be label. -``` - -The first line here is not a command, but a label. It names the next line loop$. This means we can now refer to the line by name. This is called a label. Labels get discarded when the code is turned into binary, but they're useful for our benefit for referring to lines by name, not number (address). By convention we use a $ for labels which are only important to the code in this block of code, to let others know they're not important to the overall program. The b (branch) command causes the next line to be executed to be the one at the label specified, rather than the one after it. Therefore, the next line to be executed will be this b, which will cause it to be executed again, and so on forever. Thus the processor is stuck in a nice infinite loop until it is switched off safely. - -The new line at the end of the block is intentional. The GNU toolchain expects all assembly code files to end in an empty line, so that it is sure you were really finished, and the file hasn't been cut off. If you don't put one, you get an annoying warning when the assembler runs. - -### 7 Pi Time - -So we've written the code, now to get it onto the pi. Open a terminal on your computer and change the current working directory to the parent directory of the source directory. Type make and then press enter. If any errors occur, please refer to the troubleshooting section. If not, you will have generated three files. kernel.img is the compiled image of your operating system. kernel.list is a listing of the assembly code you wrote, as it was actually generated. This is useful to check that things were generated correctly in future. The kernel.map file contains a map of where all the labels ended up, which can be useful for chasing around values. - -To install your operating system, first of all get a Raspberry PI SD card which has an operating system installed already. If you browse the files in the SD card, you should see one called kernel.img. Rename this file to something else, such as kernel_linux.img. Then, copy the file kernel.img that make generated onto the SD Card. You've just replaced the existing operating system with your own. To switch back, simply delete your kernel.img file, and rename the other one back to kernel.img. I find it is always helpful to keep a backup of you original Raspberry Pi operating system, in case you need it again. - -Put the SD card into a Raspberry Pi and turn it on. The OK LED should turn on. If not please see the troubleshooting page. If so, congratulations, you just wrote your first operating system. See [Lesson 2: OK02][12] for a guide to making the LED flash on and off. - --------------------------------------------------------------------------------- - -via: https://www.cl.cam.ac.uk/projects/raspberrypi/tutorials/os/ok01.html - -作者：[Robert Mullins][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]: http://www.cl.cam.ac.uk/~rdm34 -[b]: https://github.com/lujun9972 -[1]: https://www.cl.cam.ac.uk/projects/raspberrypi/tutorials/os/downloads.html -[2]: https://www.cl.cam.ac.uk/projects/raspberrypi/tutorials/os/images/hexadecimal1.png -[3]: https://www.cl.cam.ac.uk/projects/raspberrypi/tutorials/os/images/hexadecimal2.png -[4]: https://www.cl.cam.ac.uk/projects/raspberrypi/tutorials/os/images/hexadecimal3.png -[5]: https://www.cl.cam.ac.uk/projects/raspberrypi/tutorials/os/images/hexadecimal4.png -[6]: https://www.cl.cam.ac.uk/projects/raspberrypi/tutorials/os/images/gpioController.png -[7]: https://www.cl.cam.ac.uk/projects/raspberrypi/tutorials/os/images/binary1.png -[8]: https://www.cl.cam.ac.uk/projects/raspberrypi/tutorials/os/images/binary2.png -[9]: https://www.cl.cam.ac.uk/projects/raspberrypi/tutorials/os/images/binary3.png -[10]: https://www.cl.cam.ac.uk/projects/raspberrypi/tutorials/os/screen04.html -[11]: https://www.cl.cam.ac.uk/projects/raspberrypi/tutorials/os/images/binary4.png -[12]: https://www.cl.cam.ac.uk/projects/raspberrypi/tutorials/os/ok02.html diff --git a/sources/tech/20120202 Computer Laboratory - Raspberry Pi- Lesson 2 OK02.md b/sources/tech/20120202 Computer Laboratory - Raspberry Pi- Lesson 2 OK02.md index 9442a67708..fbdba984c3 100644 --- a/sources/tech/20120202 Computer Laboratory - Raspberry Pi- Lesson 2 OK02.md +++ b/sources/tech/20120202 Computer Laboratory - Raspberry Pi- Lesson 2 OK02.md @@ -1,5 +1,5 @@ [#]: collector: (lujun9972) -[#]: translator: ( ) +[#]: translator: (qhwdw) [#]: reviewer: ( ) [#]: publisher: ( ) [#]: url: ( ) diff --git a/sources/tech/20171206 Getting started with Turtl, an open source alternative to Evernote.md b/sources/tech/20171206 Getting started with Turtl, an open source alternative to Evernote.md index 969ef39901..968f3c546a 100644 --- a/sources/tech/20171206 Getting started with Turtl, an open source alternative to Evernote.md +++ b/sources/tech/20171206 Getting started with Turtl, an open source alternative to Evernote.md @@ -1,3 +1,5 @@ +translating---geekpi + Getting started with Turtl, an open source alternative to Evernote ====== ![Using Turtl as an open source alternative to Evernote](https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/BUS_brainstorm_island_520px.png?itok=6IUPyxkY) diff --git a/sources/tech/20180220 JSON vs XML vs TOML vs CSON vs YAML.md b/sources/tech/20180220 JSON vs XML vs TOML vs CSON vs YAML.md new file mode 100644 index 0000000000..eeb290c82b --- /dev/null +++ b/sources/tech/20180220 JSON vs XML vs TOML vs CSON vs YAML.md @@ -0,0 +1,212 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (JSON vs XML vs TOML vs CSON vs YAML) +[#]: via: (https://www.zionandzion.com/json-vs-xml-vs-toml-vs-cson-vs-yaml/) +[#]: author: (Tim Anderson https://www.zionandzion.com) + +JSON vs XML vs TOML vs CSON vs YAML +====== + + +### A Super Serious Segment About Sets, Subsets, and Supersets of Sample Serialization + +I’m a developer. I read code. I write code. I write code that writes code. I write code that writes code for other code to read. It’s all very mumbo-jumbo, but beautiful in its own way. However, that last bit, writing code that writes code for other code to read, can get more convoluted than this paragraph—quickly. There are a lot of ways to do it. One not-so-convoluted way and a favorite among the developer community is through data serialization. For those who aren’t savvy on the super buzzword I just threw at you, data serialization is the process of taking some information from one system, churning it into a format that other systems can read, and then passing it along to those other systems. + +While there are enough [data serialization formats][1] out there to bury the Burj Khalifa, they all mostly fall into two categories: + + * simplicity for humans to read and write, + * and simplicity for machines to read and write. + + + +It’s difficult to have both as we humans enjoy loosely typed, flexible formatting standards that allow us to be more expressive, whereas machines tend to enjoy being told exactly what everything is without doubt or lack of detail, and consider “strict specifications” to be their favorite flavor of Ben & Jerry’s. + +Since I’m a web developer and we’re an agency who creates websites, we’ll stick to those special formats that web systems can understand, or be made to understand without much effort, and that are particularly useful for human readability: XML, JSON, TOML, CSON, and YAML. Each has benefits, cons, and appropriate use cases. + +### Facts First + +Back in the early days of the interwebs, [some really smart fellows][2] decided to put together a standard language which every system could read and creatively named it Standard Generalized Markup Language, or SGML for short. SGML was incredibly flexible and well defined by its publishers. It became the father of languages such as XML, SVG, and HTML. All three fall under the SGML specification, but are subsets with stricter rules and shorter flexibility. + +Eventually, people started seeing a great deal of benefit in having very small, concise, easy to read, and easy to generate data that could be shared programmatically between systems with very little overhead. Around that time, JSON was born and was able to fulfil all requirements. In turn, other languages began popping up to deal with more specialized cases such as CSON, TOML, and YAML. + +### XML: Ixnayed + +Originally, the XML language was amazingly flexible and easy to write, but its drawback was that it was verbose, difficult for humans to read, really difficult for computers to read, and had a lot of syntax that wasn’t entirely necessary to communicate information. + +Today, it’s all but dead for data serialization purposes on the web. Unless you’re writing HTML or SVG, both siblings to XML, you probably aren’t going to see XML in too many other places. Some outdated systems still use it today, but using it to pass data around tends to be overkill for the web. + +I can already hear the XML greybeards beginning to scribble upon their stone tablets as to why XML is ah-may-zing, so I’ll provide a small addendum: XML can be easy to read and write by systems and people. However, it is really, and I mean ridiculously, hard to create a system that can read it to specification. Here’s a simple, beautiful example of XML: + +``` + +Gambardella, Matthew +XML Developer's Guide +Computer +44.95 +2000-10-01 +An in-depth look at creating applications +with XML. + +``` + +Wonderful. Easy to read, reason about, write, and code a system that can read and write. But consider this example: + +``` +b"> ]> + + +b b + d + +``` + +The above is 100% valid XML. Impossible to read, understand, or reason about. Writing code that can consume and understand this would cost at least 36 heads of hair and 248 pounds of coffee grounds. We don’t have that kind of time nor coffee, and most of us greybeards are balding nowadays. So let’s let it live only in our memory alongside [css hacks][3], [internet explorer 6][4], and [vacuum tubes][5]. + +### JSON: Juxtaposition Jamboree + +Okay, we’re all in agreement. XML = bad. So, what’s a good alternative? JavaScript Object Notation, or JSON for short. JSON (read like the name Jason) was invented by Brendan Eich, and made popular by the great and powerful Douglas Crockford, the [Dutch Uncle of JavaScript][6]. It’s used just about everywhere nowadays. The format is easy to write by both human and machine, fairly easy to [parse][7] with strict rules in the specification, and flexible—allowing deep nesting of data, all of the primitive data types, and interpretation of collections as either arrays or objects. JSON became the de facto standard for transferring data from one system to another. Nearly every language out there has built-in functionality for reading and writing it. + +JSON syntax is straightforward. Square brackets denote arrays, curly braces denote records, and two values separated by semicolons denote properties (or ‘keys’) on the left, and values on the right. All keys must be wrapped in double quotes: + +``` +{ +"books": [ +{ +"id": "bk102", +"author": "Crockford, Douglas", +"title": "JavaScript: The Good Parts", +"genre": "Computer", +"price": 29.99, +"publish_date": "2008-05-01", +"description": "Unearthing the Excellence in JavaScript" +} +] +} +``` + +This should make complete sense to you. It’s nice and concise, and has stripped much of the extra nonsense from XML to convey the same amount of information. JSON is king right now, and the rest of this article will go into other language formats that are nothing more than JSON boiled down in an attempt to be either more concise or more readable by humans, but follow very similar structure. + +### TOML: Truncated to Total Altruism + +TOML (Tom’s Obvious, Minimal Language) allows for defining deeply-nested data structures rather quickly and succinctly. The name-in-the-name refers to the inventor, [Tom Preston-Werner][8], an inventor and software developer who’s active in our industry. The syntax is a bit awkward when compared to JSON, and is more akin to an [ini file][9]. It’s not a bad syntax, but could take some getting used to: + +``` +[[books]] +id = 'bk101' +author = 'Crockford, Douglas' +title = 'JavaScript: The Good Parts' +genre = 'Computer' +price = 29.99 +publish_date = 2008-05-01T00:00:00+00:00 +description = 'Unearthing the Excellence in JavaScript' +``` + +A couple great features have been integrated into TOML, such as multiline strings, auto-escaping of reserved characters, datatypes such as dates, time, integers, floats, scientific notation, and “table expansion”. That last bit is special, and is what makes TOML so concise: + +``` +[a.b.c] +d = 'Hello' +e = 'World' +``` + +The above expands to the following: + +``` +{ +"a": { +"b": { +"c": { +"d": "Hello" +"e": "World" +} +} +} +} +``` + +You can definitely see how much you can save in both time and file length using TOML. There are few systems which use it or something very similar for configuration, and that is its biggest con. There simply aren’t very many languages or libraries out there written to interpret TOML. + +### CSON: Simple Samples Enslaved by Specific Systems + +First off, there are two CSON specifications. One stands for CoffeeScript Object Notation, the other stands for Cursive Script Object Notation. The latter isn’t used too often, so we won’t be getting into it. Let’s just focus on the CoffeeScript one. + +[CSON][10] will take a bit of intro. First, let’s talk about CoffeeScript. [CoffeeScript][11] is a language that runs through a compiler to generate JavaScript. It allows you to write JavaScript in a more syntactically concise way, and have it [transcompiled][12] into actual JavaScript, which you would then use in your web application. CoffeeScript makes writing JavaScript easier by removing a lot of the extra syntax necessary in JavaScript. A big one that CoffeeScript gets rid of is curly braces—no need for them. In that same token, CSON is JSON without the curly braces. It instead relies on indentation to determine hierarchy of your data. CSON is very easy to read and write and usually requires fewer lines of code than JSON because there are no brackets. + +CSON also offers up some extra niceties that JSON doesn’t have to offer. Multiline strings are incredibly easy to write, you can enter [comments][13] by starting a line with a hash, and there’s no need for separating key-value pairs with commas. + +``` +books: [ +id: 'bk102' +author: 'Crockford, Douglas' +title: 'JavaScript: The Good Parts' +genre: 'Computer' +price: 29.99 +publish_date: '2008-05-01' +description: 'Unearthing the Excellence in JavaScript' +] +``` + +Here’s the big issue with CSON. It’s **CoffeeScript** Object Notation. Meaning CoffeeScript is what you use to parse/tokenize/lex/transcompile or otherwise use CSON. CoffeeScript is the system that reads the data. If the intent of data serialization is to allow data to be passed from one system to another, and here we have a data serialization format that’s only read by a single system, well that makes it about as useful as a fireproof match, or a waterproof sponge, or that annoyingly flimsy fork part of a spork. + +If this format is adopted by other systems, it could be pretty useful in the developer world. Thus far that hasn’t happened in a comprehensive manner, so using it in alternative languages such as PHP or JAVA are a no-go. + +### YAML: Yielding Yips from Youngsters + +Developers rejoice, as YAML comes into the scene from [one of the contributors to Python][14]. YAML has the same feature set and similar syntax as CSON, a boatload of new features, and parsers available in just about every web programming language there is. It also has some extra features, like circular referencing, soft-wraps, multi-line keys, typecasting tags, binary data, object merging, and [set maps][15]. It has incredibly good human readability and writability, and is a superset of JSON, so you can use fully qualified JSON syntax inside YAML and all will work well. You almost never need quotes, and it can interpret most of your base data types (strings, integers, floats, booleans, etc.). + +``` +books: +- id: bk102 +author: Crockford, Douglas +title: 'JavaScript: The Good Parts' +genre: Computer +price: 29.99 +publish_date: !!str 2008-05-01 +description: Unearthing the Excellence in JavaScript +``` + +The younglings of the industry are rapidly adopting YAML as their preferred data serialization and system configuration format. They are smart to do so. YAML has all the benefits of being as terse as CSON, and all the features of datatype interpretation as JSON. YAML is as easy to read as Canadians are to hang out with. + +There are two issues with YAML that stick out to me, and the first is a big one. At the time of this writing, YAML parsers haven’t yet been built into very many languages, so you’ll need to use a third-party library or extension for your chosen language to parse .yaml files. This wouldn’t be a big deal, however it seems most developers who’ve created parsers for YAML have chosen to throw “additional features” into their parsers at random. Some allow [tokenization][16], some allow [chain referencing][17], some even allow inline calculations. This is all well and good (sort of), except that none of these features are part of the specification, and so are difficult to find amongst other parsers in other languages. This results in system-locking; you end up with the same issue that CSON is subject to. If you use a feature found in only one parser, other parsers won’t be able to interpret the input. Most of these features are nonsense that don’t belong in a dataset, but rather in your application logic, so it’s best to simply ignore them and write your YAML to specification. + +The second issue is there are few parsers that yet completely implement the specification. All the basics are there, but it can be difficult to find some of the more complex and newer things like soft-wraps, document markers, and circular references in your preferred language. I have yet to see an absolute need for these things, so hopefully they shouldn’t slow you down too much. With the above considered, I tend to keep to the more matured feature set presented in the [1.1 specification][18], and avoid the newer stuff found in the [1.2 specification][19]. However, programming is an ever-evolving monster, so by the time you finish reading this article, you’re likely to be able to use the 1.2 spec. + +### Final Philosophy + +The final word here is that each serialization language should be treated with a case-by-case reverence. Some are the bee’s knees when it comes to machine readability, some are the cat’s meow for human readability, and some are simply gilded turds. Here’s the ultimate breakdown: If you are writing code for other code to read, use YAML. If you are writing code that writes code for other code to read, use JSON. Finally, if you are writing code that transcompiles code into code that other code will read, rethink your life choices. + +-------------------------------------------------------------------------------- + +via: https://www.zionandzion.com/json-vs-xml-vs-toml-vs-cson-vs-yaml/ + +作者：[Tim Anderson][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.zionandzion.com +[b]: https://github.com/lujun9972 +[1]: https://en.wikipedia.org/wiki/Comparison_of_data_serialization_formats +[2]: https://en.wikipedia.org/wiki/Standard_Generalized_Markup_Language#History +[3]: https://www.quirksmode.org/css/csshacks.html +[4]: http://www.ie6death.com/ +[5]: https://en.wikipedia.org/wiki/Vacuum_tube +[6]: https://twitter.com/BrendanEich/status/773403975865470976 +[7]: https://en.wikipedia.org/wiki/Parsing#Parser +[8]: https://en.wikipedia.org/wiki/Tom_Preston-Werner +[9]: https://en.wikipedia.org/wiki/INI_file +[10]: https://github.com/bevry/cson#what-is-cson +[11]: http://coffeescript.org/ +[12]: https://en.wikipedia.org/wiki/Source-to-source_compiler +[13]: https://en.wikipedia.org/wiki/Comment_(computer_programming) +[14]: http://clarkevans.com/ +[15]: http://exploringjs.com/es6/ch_maps-sets.html +[16]: https://www.tutorialspoint.com/compiler_design/compiler_design_lexical_analysis.htm +[17]: https://en.wikipedia.org/wiki/Fluent_interface +[18]: http://yaml.org/spec/1.1/current.html +[19]: http://www.yaml.org/spec/1.2/spec.html diff --git a/sources/tech/20180606 Working with modules in Fedora 28.md b/sources/tech/20180606 Working with modules in Fedora 28.md index 9a45d3367b..ba92a626f8 100644 --- a/sources/tech/20180606 Working with modules in Fedora 28.md +++ b/sources/tech/20180606 Working with modules in Fedora 28.md @@ -1,3 +1,5 @@ +translating----geekpi + Working with modules in Fedora 28 ====== ![](https://fedoramagazine.org/wp-content/uploads/2018/05/modules-workingwith-816x345.jpg) diff --git a/sources/tech/20181128 Turn an old Linux desktop into a home media center.md b/sources/tech/20181128 Turn an old Linux desktop into a home media center.md deleted file mode 100644 index eed213a42e..0000000000 --- a/sources/tech/20181128 Turn an old Linux desktop into a home media center.md +++ /dev/null @@ -1,87 +0,0 @@ -[#]: collector: (lujun9972) -[#]: translator: (geekpi) -[#]: reviewer: ( ) -[#]: publisher: ( ) -[#]: subject: (Turn an old Linux desktop into a home media center) -[#]: via: (https://opensource.com/article/18/11/old-linux-desktop-new-home-media-center) -[#]: author: ([Alan Formy-Duval](https://opensource.com/users/alanfdoss)) -[#]: url: ( ) - -Turn an old Linux desktop into a home media center -====== -Repurpose an outdated computer to browse the internet and watch videos on your big screen TV. -![](https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/migration_innovation_computer_software.png?itok=VCFLtd0q) - -My first attempt to set up an "entertainment PC" was back in the late 1990s, using a plain old desktop computer with a Trident ProVidia 9685 PCI graphics card. I used what was known as a "TV-out" card, which had an extra output to connect to a standard television set. The onscreen result didn't look very nice and there was no audio output. And it was ugly: I had an S-Video cable running across my living room floor to my 19" Sony Trinitron CRT TV set. - -I had the same sad result from Linux and Windows 98. After struggling with systems that never looked right, I gave up for a few years. Thankfully, today we have HDMI with its vastly better performance and standardized resolution, which makes an inexpensive home media center a reality. - -My new media center entertainment computer is actually my old Ubuntu Linux desktop, which I recently replaced with something faster. The computer became too slow for work, but its AMD Phenom II X4 965 processor at 3.4GHz and 8GB of RAM are good enough for general browsing and video streaming. - -Here are the steps I took to get the best possible performance out of this old system for its new role. - -### Hardware - -First, I removed unnecessary devices including a card reader, hard drives, DVD drive, and a rear-mounted USB card, and I added a PCI-Express WiFi card. I installed Ubuntu to a single solid-state drive (SSD), which can really improve the performance of any older system. - -### BIOS - -In the BIOS, I disabled all unused devices, such as floppy and IDE drive controllers. I disabled onboard video because I installed an NVidia GeForce GTX 650 PCI Express graphics card with an HDMI output. I also disabled onboard audio because the NVidia graphics card chipset provides audio. - -### Audio - -The Nvidia GeForce GTX audio device is listed in the GNOME Control Center's sound settings as a GK107 HDMI Audio Controller, so a single HDMI cable handles both audio and video. There's no need for an audio cable connected to the onboard audio output jack. - -![Sound settings screenshot][2] - -HDMI audio controller shown in GNOME sound settings. - -### Keyboard and mouse - -I have a wireless keyboard and mouse, both from Logitech. When I installed them, I plugged in both peripherals' USB receivers; they worked, but I often had signal-response problems. Then I discovered one was labeled a Unifying Receiver, which meant it can handle multiple Logitech input devices on its own. Logitech doesn't provide software to configure Unifying Receivers in Linux; fortunately, the open source utility [Solaar][3] does. Using a single receiver solved my input performance issues. - -![Solaar][5] - -Solaar Unifying Receiver interface. - -### Video - -It was initially hard to read fonts on my 47" flat-panel TV, so I enabled "Large Text" under Universal Access. I downloaded some wallpapers matching the TV's 1920x1080 resolution that look fantastic! - -### Final touches - -I needed to balance the computer's cooling needs with my desire for unimpeded entertainment. Since this is a standard ATX mini-tower computer, I made sure I had just enough fans with carefully configured temperature settings in the BIOS to reduce fan noise. I also placed the computer behind my entertainment console to further block fan noise but positioned so I can reach the power button. - -The result is a simple machine that is not overly loud and uses only two cables—AC power and HDMI. It should be able to run any mainstream or specialized media center Linux distribution. I don't expect to do too much high-end gaming because that may require more processing horsepower. - -![Showing Ubuntu Linux About page onscreen][7] - -Ubuntu Linux About page. - -![YouTube on the big screen][9] - -Testing a YouTube video on the big screen. - -I haven't yet installed a dedicated media center distribution of Linux like [Kodi][10]. For now, it is running Ubuntu Linux 18.04.1 LTS and is very stable. - -This was a fun challenge to make the best of what I already had rather than buying new hardware. This is just one benefit of open source software. Eventually, I will probably replace it with a smaller, quieter system with a media-center case or another small box, but for now, it meets my needs quite well. - --------------------------------------------------------------------------------- - -via: https://opensource.com/article/18/11/old-linux-desktop-new-home-media-center - -作者：[Alan Formy-Duval][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/alanfdoss -[b]: https://github.com/lujun9972 -[2]: https://opensource.com/sites/default/files/uploads/soundsettings.png (Sound settings screenshot) -[3]: https://pwr.github.io/Solaar/ -[5]: https://opensource.com/sites/default/files/uploads/solaar_interface.png (Solaar) -[7]: https://opensource.com/sites/default/files/uploads/finalresult1.png (Showing Ubuntu Linux About page onscreen) -[9]: https://opensource.com/sites/default/files/uploads/finalresult2.png (YouTube on the big screen) -[10]: https://kodi.tv/ diff --git a/sources/tech/20181209 Powers of two, powers of Linux- 2048 at the command line.md b/sources/tech/20181209 Powers of two, powers of Linux- 2048 at the command line.md deleted file mode 100644 index 1c7d61329f..0000000000 --- a/sources/tech/20181209 Powers of two, powers of Linux- 2048 at the command line.md +++ /dev/null @@ -1,52 +0,0 @@ -[#]: collector: (lujun9972) -[#]: translator: (geekpi) -[#]: reviewer: ( ) -[#]: publisher: ( ) -[#]: url: ( ) -[#]: subject: (Powers of two, powers of Linux: 2048 at the command line) -[#]: via: (https://opensource.com/article/18/12/linux-toy-2048) -[#]: author: (Jason Baker https://opensource.com/users/jason-baker) - -Powers of two, powers of Linux: 2048 at the command line -====== -Looking for a terminal-based game to pass the time? Look no further than 2048-cli. -![](https://opensource.com/sites/default/files/styles/image-full-size/public/uploads/linux-toy-2048.png?itok=3M6S-n1a) - -Hello and welcome to today's installment of the Linux command-line toys advent calendar. Every day, we look at a different toy for your terminal: it could be a game or any simple diversion that helps you have fun. - -Maybe you have seen various selections from our calendar before, but we hope there’s at least one new thing for everyone. - -Today's toy is a [command-line version][1] of one of my all-time favorite casual games, [2048][2] (which itself is a clone of another clone). - -To play, you just slide blocks up, down, left, and right to combine matching pairs and increment numbers, until you've made a block that is 2048 in size. The catch (and the challenge), is that you can't just move one block; instead, you move every block on the screen. - -It's simple, fun, and easy to get lost in it for hours. This 2048 clone, [2048-][1][cli][1], is by Marc Tiehuis and written in C, and made available as open source under an MIT license. You can find the source code [on GitHub][1], where you can also get installation instructions for your platform. Since it was packaged for Fedora, for me, installing it was as simple as: - -``` -$ sudo dnf install 2048-cli -``` - -That's it, have fun! - -![](https://opensource.com/sites/default/files/uploads/linux-toy-2048-animated_0.gif) - -Do you have a favorite command-line toy that you think I ought to profile? The calendar for this series is mostly filled out but I've got a few spots left. Let me know in the comments below, and I'll check it out. If there's space, I'll try to include it. If not, but I get some good submissions, I'll do a round-up of honorable mentions at the end. - -Check out yesterday's toy, [Play Tetris at your Linux terminal][3], and check back tomorrow for another! - --------------------------------------------------------------------------------- - -via: https://opensource.com/article/18/12/linux-toy-2048 - -作者：[Jason Baker][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/jason-baker -[b]: https://github.com/lujun9972 -[1]: https://github.com/tiehuis/2048-cli -[2]: https://github.com/gabrielecirulli/2048 -[3]: https://opensource.com/article/18/12/linux-toy-tetris diff --git a/sources/tech/20181211 Winterize your Bash prompt in Linux.md b/sources/tech/20181211 Winterize your Bash prompt in Linux.md deleted file mode 100644 index c952f0c18d..0000000000 --- a/sources/tech/20181211 Winterize your Bash prompt in Linux.md +++ /dev/null @@ -1,85 +0,0 @@ -[#]: collector: (lujun9972) -[#]: translator: (geekpi) -[#]: reviewer: ( ) -[#]: publisher: ( ) -[#]: url: ( ) -[#]: subject: (Winterize your Bash prompt in Linux) -[#]: via: (https://opensource.com/article/18/12/linux-toy-bash-prompt) -[#]: author: (Jason Baker https://opensource.com/users/jason-baker) - -Winterize your Bash prompt in Linux -====== -Your Linux terminal probably supports Unicode, so why not take advantage of that and add a seasonal touch to your prompt? -![](https://opensource.com/sites/default/files/styles/image-full-size/public/uploads/linux-toy-bash-prompt.png?itok=HK_kVn37) - -Hello once again for another installment of the Linux command-line toys advent calendar. If this is your first visit to the series, you might be asking yourself what a command-line toy even is? Really, we're keeping it pretty open-ended: It's anything that's a fun diversion at the terminal, and we're giving bonus points for anything holiday-themed. - -Maybe you've seen some of these before, maybe you haven't. Either way, we hope you have fun. - -Today's toy is super-simple: It's your Bash prompt. Your Bash prompt? Yep! We've got a few more weeks of the holiday season left to stare at it, and even more weeks of winter here in the northern hemisphere, so why not have some fun with it. - -Your Bash prompt currently might be a simple dollar sign ( **$** ), or more likely, it's something a little longer. If you're not sure what makes up your Bash prompt right now, you can find it in an environment variable called $PS1. To see it, type: - -``` -echo $PS1 -``` - -For me, this returns: - -``` -[\u@\h \W]\$ -``` - -The **\u** , **\h** , and **\W** are special characters for username, hostname, and working directory. There are others you can use as well; for help building out your Bash prompt, you can use [EzPrompt][1], an online generator of PS1 configurations that includes lots of options including date and time, Git status, and more. - -You may have other variables that make up your Bash prompt set as well; **$PS2** for me contains the closing brace of my command prompt. See [this article][2] for more information. - -To change your prompt, simply set the environment variable in your terminal like this: - -``` -$ PS1='\u is cold: ' -jehb is cold: -``` - -To set it permanently, add the same code to your **/etc/bashrc **using your favorite text editor. - -So what does this have to do with winterization? Well, chances are on a modern machine, your terminal support Unicode, so you're not limited to the standard ASCII character set. You can use any emoji that's a part of the Unicode specification, including a snowflake ❄, a snowman ☃, or a pair of skis 🎿. You've got plenty of wintery options to choose from. - -``` -🎄 Christmas Tree -🧥 Coat -🦌 Deer -🧤 Gloves -🤶 Mrs. Claus -🎅 Santa Claus -🧣 Scarf -🎿 Skis -🏂 Snowboarder -❄ Snowflake -☃ Snowman -⛄ Snowman Without Snow -🎁 Wrapped Gift -``` - -Pick your favorite, and enjoy some winter cheer. Fun fact: modern filesystems also support Unicode characters in their filenames, meaning you can technically name your next program **"❄❄❄❄❄.py"**. That said, please don't. - -Do you have a favorite command-line toy that you think I ought to include? The calendar for this series is mostly filled out but I've got a few spots left. Let me know in the comments below, and I'll check it out. If there's space, I'll try to include it. If not, but I get some good submissions, I'll do a round-up of honorable mentions at the end. - -Check out yesterday's toy, [Snake your way across your Linux terminal][3], and check back tomorrow for another! - --------------------------------------------------------------------------------- - -via: https://opensource.com/article/18/12/linux-toy-bash-prompt - -作者：[Jason Baker][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/jason-baker -[b]: https://github.com/lujun9972 -[1]: http://ezprompt.net/ -[2]: https://access.redhat.com/solutions/505983 -[3]: https://opensource.com/article/18/12/linux-toy-snake diff --git a/sources/tech/20181221 Large files with Git- LFS and git-annex.md b/sources/tech/20181221 Large files with Git- LFS and git-annex.md index 29a76f810f..2e7b9a9b74 100644 --- a/sources/tech/20181221 Large files with Git- LFS and git-annex.md +++ b/sources/tech/20181221 Large files with Git- LFS and git-annex.md @@ -1,5 +1,5 @@ [#]: collector: (lujun9972) -[#]: translator: ( ) +[#]: translator: (runningwater) [#]: reviewer: ( ) [#]: publisher: ( ) [#]: url: ( ) @@ -96,7 +96,7 @@ via: https://anarc.at/blog/2018-12-21-large-files-with-git/ 作者：[Anarc.at][a] 选题：[lujun9972][b] -译者：[译者ID](https://github.com/译者ID) +译者：[runningwater](https://github.com/runningwater) 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 diff --git a/sources/tech/20181227 Asciinema - Record And Share Your Terminal Sessions On The Fly.md b/sources/tech/20181227 Asciinema - Record And Share Your Terminal Sessions On The Fly.md index 769780a79f..20bcfbe26d 100644 --- a/sources/tech/20181227 Asciinema - Record And Share Your Terminal Sessions On The Fly.md +++ b/sources/tech/20181227 Asciinema - Record And Share Your Terminal Sessions On The Fly.md @@ -1,5 +1,5 @@ [#]: collector: (lujun9972) -[#]: translator: ( ) +[#]: translator: (bestony) [#]: reviewer: ( ) [#]: publisher: ( ) [#]: url: ( ) diff --git a/sources/tech/20190103 s-tui- A Terminal Tool To Monitor CPU Temperature, Frequency, Power And Utilization In Linux.md b/sources/tech/20190103 s-tui- A Terminal Tool To Monitor CPU Temperature, Frequency, Power And Utilization In Linux.md new file mode 100644 index 0000000000..8861e90cac --- /dev/null +++ b/sources/tech/20190103 s-tui- A Terminal Tool To Monitor CPU Temperature, Frequency, Power And Utilization In Linux.md @@ -0,0 +1,131 @@ +[#]: collector: (lujun9972) +[#]: translator: (geekpi) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (s-tui: A Terminal Tool To Monitor CPU Temperature, Frequency, Power And Utilization In Linux) +[#]: via: (https://www.2daygeek.com/s-tui-stress-terminal-ui-monitor-linux-cpu-temperature-frequency/) +[#]: author: (Prakash Subramanian https://www.2daygeek.com/author/prakash/) + +s-tui: A Terminal Tool To Monitor CPU Temperature, Frequency, Power And Utilization In Linux +====== + +By default every Linux administrator would go with **[lm_sensors to monitor CPU temperature][1]**. + +lm_sensors (Linux monitoring sensors) is a free and open-source application that provides tools and drivers for monitoring temperatures, voltage, and fans. + +It’s a CLI utility and if you are looking for alternative tools. + +I would suggest you to go for s-tui. + +It’s a Stress Terminal UI which helps administrator to view CPU temperature with colors. + +### What is s-tui + +s-tui is a terminal UI for monitoring your computer. s-tui allows to monitor CPU temperature, frequency, power and utilization in a graphical way from the terminal. + +Also, shows performance dips caused by thermal throttling, it requires minimal resources and doesn’t requires X-server. It was written in Python and requires root privilege to use this. + +s-tui is a self-contained application which can run out-of-the-box and doesn’t need config files to drive its core features. + +s-tui uses psutil to probe some of your hardware information. If your hardware is not supported, you might not see all the information. + +Running s-tui as root gives access to the maximum Turbo Boost frequency available to your CPU when stressing all cores. + +It uses Stress utility in the background to check the temperature of its components do not exceed their acceptable range by imposes certain types of compute stress on your system. + +Running an overclocked PC is fine as long as it is stable and that the temperature of its components do not exceed their acceptable range. + +There are several programs available to assess system stability through stress testing the system and thereby the overclock level. + +### How to Install s-tui In Linux + +It was written in Python and pip installation is a recommended method to install s-tui on Linux. Make sure you should have installed python-pip package on your system. If no, use the following command to install it. + +For Debian/Ubuntu users, use **[Apt Command][2]** or **[Apt-Get Command][3]** to install pip package. + +``` +$ sudo apt install python-pip stress +``` + +For Archlinux users, use **[Pacman Command][4]** to install pip package. + +``` +$ sudo pacman -S python-pip stress +``` + +For Fedora users, use **[DNF Command][5]** to install pip package. + +``` +$ sudo dnf install python-pip stress +``` + +For CentOS/RHEL users, use **[YUM Command][6]** to install pip package. + +``` +$ sudo yum install python-pip stress +``` + +For openSUSE users, use **[Zypper Command][7]** to install pip package. + +``` +$ sudo zypper install python-pip stress +``` + +Finally run the following **[pip command][8]** to install s-tui tool in Linux. + +For Python 2.x: + +``` +$ sudo pip install s-tui +``` + +For Python 3.x: + +``` +$ sudo pip3 install s-tui +``` + +### How to Access s-tui + +As i told in the beginning of the article. It requires root privilege to get all the information from your system. Just run the following command to launch s-tui. + +``` +$ sudo s-tui +``` + +![][10] + +By default it enable hardware monitoring and select the “Stress” option to do the stress test on your system. +![][11] + +To check other options, navigate to help page. + +``` +$ s-tui --help +``` + +-------------------------------------------------------------------------------- + +via: https://www.2daygeek.com/s-tui-stress-terminal-ui-monitor-linux-cpu-temperature-frequency/ + +作者：[Prakash Subramanian][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/prakash/ +[b]: https://github.com/lujun9972 +[1]: https://www.2daygeek.com/view-check-cpu-hard-disk-temperature-linux/ +[2]: https://www.2daygeek.com/apt-command-examples-manage-packages-debian-ubuntu-systems/ +[3]: https://www.2daygeek.com/apt-get-apt-cache-command-examples-manage-packages-debian-ubuntu-systems/ +[4]: https://www.2daygeek.com/pacman-command-examples-manage-packages-arch-linux-system/ +[5]: https://www.2daygeek.com/dnf-command-examples-manage-packages-fedora-system/ +[6]: https://www.2daygeek.com/yum-command-examples-manage-packages-rhel-centos-systems/ +[7]: https://www.2daygeek.com/zypper-command-examples-manage-packages-opensuse-system/ +[8]: https://www.2daygeek.com/install-pip-manage-python-packages-linux/ +[9]: data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7 +[10]: https://www.2daygeek.com/wp-content/uploads/2018/12/s-tui-stress-terminal-ui-monitor-linux-cpu-temperature-frequency-1.jpg +[11]: https://www.2daygeek.com/wp-content/uploads/2018/12/s-tui-stress-terminal-ui-monitor-linux-cpu-temperature-frequency-2.jpg diff --git a/sources/tech/20190104 Managing dotfiles with rcm.md b/sources/tech/20190104 Managing dotfiles with rcm.md new file mode 100644 index 0000000000..88e239caf8 --- /dev/null +++ b/sources/tech/20190104 Managing dotfiles with rcm.md @@ -0,0 +1,116 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Managing dotfiles with rcm) +[#]: via: (https://fedoramagazine.org/managing-dotfiles-rcm/) +[#]: author: (Link Dupont https://fedoramagazine.org/author/linkdupont/) + +Managing dotfiles with rcm +====== + +![](https://fedoramagazine.org/wp-content/uploads/2018/12/dotfiles-816x345.jpg) + +A hallmark feature of many GNU/Linux programs is the easy-to-edit configuration file. Nearly all common free software programs store configuration settings inside a plain text file, often in a structured format like JSON, YAML or [“INI-like”][1]. These configuration files are frequently found hidden inside a user’s home directory. However, a basic ls won’t reveal them. UNIX standards require that any file or directory name that begins with a period (or “dot”) is considered “hidden” and will not be listed in directory listings unless requested by the user. For example, to list all files using the ls program, pass the -a command-line option. + +Over time, these configuration files become highly customized, and managing them becomes increasingly more challenging as time goes on. Not only that, but keeping them synchronized between multiple computers is a common challenge in large organizations. Finally, many users find a sense of pride in their unique configuration settings and want an easy way to share them with friends. That’s where **rcm** steps in. + +**rcm** is a “rc” file management suite (“rc” is another convention for naming configuration files that has been adopted by some GNU/Linux programs like screen or bash). **rcm** provides a suite of commands to manage and list files it tracks. Install **rcm** using **dnf**. + +### Getting started + +By default, **rcm** uses ~/.dotfiles for storing all the dotfiles it manages. A managed dotfile is actually stored inside ~/.dotfiles, and a symlink is placed in the expected file’s location. For example, if ~/.bashrc is tracked by **rcm** , a long listing would look like this. + +``` +[link@localhost ~]$ ls -l ~/.bashrc +lrwxrwxrwx. 1 link link 27 Dec 16 05:19 .bashrc -> /home/link/.dotfiles/bashrc +[link@localhost ~]$ +``` + +**rcm** consists of 4 commands: + + * mkrc – convert a file into a dotfile managed by rcm + * lsrc – list files managed by rcm + * rcup – synchronize dotfiles managed by rcm + * rcdn – remove all the symlinks managed by rcm + + + +### Share bashrc across two computers + +It is not uncommon today for a user to have shell accounts on more than one computer. Keeping dotfiles synchronized between those computers can be a challenge. This scenario will present one possible solution, using only **rcm** and **git**. + +First, convert (or “bless”) a file into a dotfile managed by **rcm** with mkrc. + +``` +[link@localhost ~]$ mkrc -v ~/.bashrc +Moving... +'/home/link/.bashrc' -> '/home/link/.dotfiles/bashrc' +Linking... +'/home/link/.dotfiles/bashrc' -> '/home/link/.bashrc' +[link@localhost ~]$ +``` + +Next, verify the listings are correct with lsrc. + +``` +[link@localhost ~]$ lsrc +/home/link/.bashrc:/home/link/.dotfiles/bashrc +[link@localhost ~]$ +``` + +Now create a git repository inside ~/.dotfiles and set up an accessible remote repository using your choice of hosted git repositories. Commit the bashrc file and push a new branch. + +``` +[link@localhost ~]$ cd ~/.dotfiles +[link@localhost .dotfiles]$ git init +Initialized empty Git repository in /home/link/.dotfiles/.git/ +[link@localhost .dotfiles]$ git remote add origin git@github.com:linkdupont/dotfiles.git +[link@localhost .dotfiles]$ git add bashrc +[link@localhost .dotfiles]$ git commit -m "initial commit" +[master (root-commit) b54406b] initial commit +1 file changed, 15 insertions(+) +create mode 100644 bashrc +[link@localhost .dotfiles]$ git push -u origin master +... +[link@localhost .dotfiles]$ +``` + +On the second machine, clone this repository into ~/.dotfiles. + +``` +[link@remotehost ~]$ git clone git@github.com:linkdupont/dotfiles.git ~/.dotfiles +... +[link@remotehost ~]$ +``` + +Now update the symlinks managed by **rcm** with rcup. + +``` +[link@remotehost ~]$ rcup -v +replacing identical but unlinked /home/link/.bashrc +removed '/home/link/.bashrc' +'/home/link/.dotfiles/bashrc' -> '/home/link/.bashrc' +[link@remotehost ~]$ +``` + +Overwrite the existing ~/.bashrc (if it exists) and restart the shell. + +That’s it! The host-specific option (-o) is a useful addition to the scenario above. And as always, be sure to read the manpages; they contain a wealth of example commands. + + +-------------------------------------------------------------------------------- + +via: https://fedoramagazine.org/managing-dotfiles-rcm/ + +作者：[Link Dupont][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/linkdupont/ +[b]: https://github.com/lujun9972 +[1]: https://en.wikipedia.org/wiki/INI_file diff --git a/sources/tech/20190104 Search, Study And Practice Linux Commands On The Fly.md b/sources/tech/20190104 Search, Study And Practice Linux Commands On The Fly.md new file mode 100644 index 0000000000..fa92d3450a --- /dev/null +++ b/sources/tech/20190104 Search, Study And Practice Linux Commands On The Fly.md @@ -0,0 +1,223 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Search, Study And Practice Linux Commands On The Fly!) +[#]: via: (https://www.ostechnix.com/search-study-and-practice-linux-commands-on-the-fly/) +[#]: author: (SK https://www.ostechnix.com/author/sk/) + +Search, Study And Practice Linux Commands On The Fly! +====== + +![](https://www.ostechnix.com/wp-content/uploads/2019/01/tldr-720x340.png) + +The title may look like sketchy and click bait. Allow me to explain what I am about to explain in this tutorial. Let us say you want to download an archive file, extract it and move the file from one location to another from command line. As per the above scenario, we may need at least three Linux commands, one for downloading the file, one for extracting the downloaded file and one for moving the file. If you’re intermediate or advanced Linux user, you could do this easily with an one-liner command or a script in few seconds/minutes. But, if you are a noob who don’t know much about Linux commands, you might need little help. + +Of course, a quick google search may yield many results. Or, you could use [**man pages**][1]. But some man pages are really long, comprehensive and lack in useful example. You might need to scroll down for quite a long time when you’re looking for a particular information on the specific flags/options. Thankfully, there are some [**good alternatives to man pages**][2], which are focused on mostly practical commands. One such good alternative is **TLDR pages**. Using TLDR pages, we can quickly and easily learn a Linux command with practical examples. To access the TLDR pages, we require a TLDR client. There are many clients available. Today, we are going to learn about one such client named **“Tldr++”**. + +Tldr++ is a fast and interactive tldr client written with **Go** programming language. Unlike the other Tldr clients, it is fully interactive. That means, you can pick a command, read all examples , and immediately run any command without having to retype or copy/paste each command in the Terminal. Still don’t get it? No problem. Read on to learn and practice Linux commands on the fly. + +### Install Tldr++ + +Installing Tldr++ is very simple. Download tldr++ latest version from the [**releases page**][3]. Extract it and move the tldr++ binary to your $PATH. + +``` +$ wget https://github.com/isacikgoz/tldr/releases/download/v0.5.0/tldr_0.5.0_linux_amd64.tar.gz + +$ tar xzf tldr_0.5.0_linux_amd64.tar.gz + +$ sudo mv tldr /usr/local/bin + +$ sudo chmod +x /usr/local/bin/tldr +``` + +Now, run ‘tldr’ binary to populate the tldr pages in your local system. + +``` +$ tldr +``` + +Sample output: + +``` +Enumerating objects: 6, done. +Counting objects: 100% (6/6), done. +Compressing objects: 100% (6/6), done. +Total 18157 (delta 0), reused 3 (delta 0), pack-reused 18151 +Successfully cloned into: /home/sk/.local/share/tldr +``` + +![](https://www.ostechnix.com/wp-content/uploads/2019/01/tldr-2.png) + +Tldr++ is available in AUR. If you’re on Arch Linux, you can install it using any AUR helper, for example [**YaY**][4]. Make sure you have removed any existing tldr client from your system and run the following command to install tldr++. + +``` +$ yay -S tldr++ +``` + +Alternatively, you can build from source as described below. Since Tldr++ is written using Go language, make sure you have installed it on your Linux box. If it isn’t installed yet, refer the following guide. + ++ [How To Install Go Language In Linux](https://www.ostechnix.com/install-go-language-linux/) + +After installing Go, run the following command to install Tldr++. + +``` +$ go get -u github.com/isacikgoz/tldr +``` + +This command will download the contents of tldr repository in a folder named **‘go’** in the current working directory. + +Now run the ‘tldr’ binary to populate all tldr pages in your local system using command: + +``` +$ go/bin/tldr +``` + +Sample output: + +![][6] + +Finally, copy the tldr binary to your PATH. + +``` +$ sudo mv tldr /usr/local/bin +``` + +It is time to see some examples. + +### Tldr++ Usage + +Type ‘tldr’ command without any options to display all command examples in alphabetical order. + +![][7] + +Use the **UP/DOWN arrows** to navigate through the commands, type any letters to search or type a command name to view the examples of that respective command. Press **?** for more and **Ctrl+c** to return/exit. + +To display the example commands of a specific command, for example **apt** , simply do: + +``` +$ tldr apt +``` + +![][8] + +Choose any example command from the list and hit ENTER. You will see a *** symbol** before the selected command. For example, I choose the first command i.e ‘sudo apt update’. Now, it will ask you whether to continue or not. If the command is correct, just type ‘y’ to continue and type your sudo password to run the selected command. + +![][9] + +See? You don’t need to copy/paste or type the actual command in the Terminal. Just choose it from the list and run on the fly! + +There are hundreds of Linux command examples are available in Tldr pages. You can choose one or two commands per day and learn them thoroughly. And keep this practice everyday to learn as much as you can. + +### Learn And Practice Linux Commands On The Fly Using Tldr++ + +Now think of the scenario that I mentioned in the first paragraph. You want to download a file, extract it and move it to different location and make it executable. Let us see how to do it interactively using Tldr++ client. + +**Step 1 – Download a file from Internet** + +To download a file from command line, we mostly use **‘curl’** or **‘wget’** commands. Let me use ‘wget’ to download the file. To open tldr page of wget command, just run: + +``` +$ tldr wget +``` + +Here is the examples of wget command. + +![](https://www.ostechnix.com/wp-content/uploads/2019/01/wget-tldr.png) + +You can use **UP/DOWN** arrows to go through the list of commands. Once you choose the command of your choice, press ENTER. Here I chose the first command. + +Now, enter the path of the file to download. + +![](https://www.ostechnix.com/wp-content/uploads/2019/01/tldr-3.png) + +You will then be asked to confirm if it is the correct command or not. If the command is correct, simply type ‘yes’ or ‘y’ to start downloading the file. + +![][10] + +We have downloaded the file. Let us go ahead and extract this file. + +**Step 2 – Extract downloaded archive** + +We downloaded the **tar.gz** file. So I am going to open the ‘tar’ tldr page. + +``` +$ tldr tar +``` + +You will see the list of example commands. Go through the examples and find which command is suitable to extract tar.gz(gzipped archive) file and hit ENTER key. In our case, it is the third command. + +![][11] + +Now, you will be prompted to enter the path of the tar.gz file. Just type the path and hit ENTER key. Tldr++ supports smart file suggestions. That means it will suggest the file name automatically as you type. Just press TAB key for auto-completion. + +![][12] + +If you downloaded the file to some other location, just type the full path, for example **/home/sk/Downloads/tldr_0.5.0_linux_amd64.tar.gz.** + +Once you enter the path of the file to extract, press ENTER and then, type ‘y’ to confirm. + +![][13] + +**Step 3 – Move file from one location to another** + +We extracted the archive. Now we need to move the file to another location. To move the files from one location to another, we use ‘mv’ command. So, let me open the tldr page for mv command. + +``` +$ tldr mv +``` + +Choose the correct command to move the files from one location to another. In our case, the first command will work, so let me choose it. + +![][14] + +Type the path of the file that you want to move and enter the destination path and hit ENTER key. + +![][15] + +**Note:** Type **y!** or **yes!** to run command with **sudo** privileges. + +As you see in the above screenshot, I moved the file named **‘tldr’** to **‘/usr/local/bin/’** location. + +For more details, refer the project’s GitHub page given at the end. + + +### Conclusion + +Don’t get me wrong. **Man pages are great!** There is no doubt about it. But, as I already said, many man pages are comprehensive and doesn’t have useful examples. There is no way I could memorize all lengthy commands with tricky flags. Some times I spent much time on man pages and remained clueless. The Tldr pages helped me to find what I need within few minutes. Also, we use some commands once in a while and then we forget them completely. Tldr pages on the other hand actually helps when it comes to using commands we rarely use. Tldr++ client makes this task much easier with smart user interaction. Give it a go and let us know what you think about this tool in the comment section below. + +And, that’s all. More good stuffs to come. Stay tuned! + +Good luck! + + + +-------------------------------------------------------------------------------- + +via: https://www.ostechnix.com/search-study-and-practice-linux-commands-on-the-fly/ + +作者：[SK][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.ostechnix.com/author/sk/ +[b]: https://github.com/lujun9972 +[1]: https://www.ostechnix.com/learn-use-man-pages-efficiently/ +[2]: https://www.ostechnix.com/3-good-alternatives-man-pages-every-linux-user-know/ +[3]: https://github.com/isacikgoz/tldr/releases +[4]: https://www.ostechnix.com/yay-found-yet-another-reliable-aur-helper/ +[5]: data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7 +[6]: http://www.ostechnix.com/wp-content/uploads/2019/01/tldr-1.png +[7]: http://www.ostechnix.com/wp-content/uploads/2019/01/tldr-11.png +[8]: http://www.ostechnix.com/wp-content/uploads/2019/01/tldr-12.png +[9]: http://www.ostechnix.com/wp-content/uploads/2019/01/tldr-13.png +[10]: http://www.ostechnix.com/wp-content/uploads/2019/01/tldr-4.png +[11]: http://www.ostechnix.com/wp-content/uploads/2019/01/tldr-6.png +[12]: http://www.ostechnix.com/wp-content/uploads/2019/01/tldr-7.png +[13]: http://www.ostechnix.com/wp-content/uploads/2019/01/tldr-8.png +[14]: http://www.ostechnix.com/wp-content/uploads/2019/01/tldr-9.png +[15]: http://www.ostechnix.com/wp-content/uploads/2019/01/tldr-10.png diff --git a/sources/tech/20190105 Setting up an email server, part 1- The Forwarder.md b/sources/tech/20190105 Setting up an email server, part 1- The Forwarder.md new file mode 100644 index 0000000000..c6c520e339 --- /dev/null +++ b/sources/tech/20190105 Setting up an email server, part 1- The Forwarder.md @@ -0,0 +1,224 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Setting up an email server, part 1: The Forwarder) +[#]: via: (https://blog.jak-linux.org/2019/01/05/setting-up-an-email-server-part1/) +[#]: author: (Julian Andres Klode https://blog.jak-linux.org/) + +Setting up an email server, part 1: The Forwarder +====== + +This week, I’ve been working on rolling out mail services on my server. I started working on a mail server setup at the end of November, while the server was not yet in use, but only for about two days, and then let it rest. + +As my old shared hosting account expired on January 1, I had to move mail forwarding duties over to the new server. Yes forwarding - I do plan to move hosting the actual email too, but at the moment it’s “just” forwarding to gmail. + +### The Software + +As you might know from the web server story, my server runs on Ubuntu 18.04. I set up a mail server on this system using + + * [Postfix][1] for SMTP duties (warning, they oddly do not have an https page) + * [rspamd][2] for spam filtering, and signing DKIM / ARC + * [bind9][3] for DNS resolving + * [postsrsd][4] for SRS + + + +You might wonder why bind9 is in there. It turns out that DNS blacklists used by spam filters block the caching DNS servers you usually use, so you have to use your own recursive DNS server. Ubuntu offers you the choice between bind9 and dnsmasq in main, and it seems like bind9 is more appropriate here than dnsmasq. + +### Setting up postfix + +Most of the postfix configuration is fairly standard. So, let’s skip TLS configuration and outbound SMTP setups (this is email, and while they support TLS, it’s all optional, so let’s not bother that much here). + +The most important part is restrictions in `main.cf`. + +First of all, relay restrictions prevent us from relaying emails to weird domains: + +``` +# Relay Restrictions +smtpd_relay_restrictions = reject_non_fqdn_recipient reject_unknown_recipient_domain permit_mynetworks permit_sasl_authenticated defer_unauth_destination +``` + +We also only accept mails from hosts that know their own full qualified name: + +``` +# Helo restrictions (hosts not having a proper fqdn) +smtpd_helo_required = yes +smtpd_helo_restrictions = permit_mynetworks reject_invalid_helo_hostname reject_non_fqdn_helo_hostname reject_unknown_helo_hostname +``` + +We also don’t like clients (other servers) that send data too early, or have an unknown hostname: + +``` +smtpd_data_restrictions = reject_unauth_pipelining +smtpd_client_restrictions = permit_mynetworks reject_unknown_client_hostname +``` + +I also set up a custom apparmor profile that’s pretty lose, I plan to migrate to the one in the apparmor git eventually but it needs more testing and some cleanup. + +### Sender rewriting scheme + +For SRS using postsrsd, we define the `SRS_DOMAIN` in `/etc/default/postsrsd` and then configure postfix to talk to it: + +``` +# Handle SRS for forwarding +recipient_canonical_maps = tcp:localhost:10002 +recipient_canonical_classes= envelope_recipient,header_recipient + +sender_canonical_maps = tcp:localhost:10001 +sender_canonical_classes = envelope_sender +``` + +This has a minor issue that it also rewrites the `Return-Path` when it delivers emails locally, but as I am only forwarding, I’m worrying about that later. + +### rspamd basics + +rspamd is a great spam filtering system. It uses a small core written in C and a bunch of Lua plugins, such as: + + * IP score, which keeps track of how good a specific server was in the past + * Replies, which can check whether an email is a reply to another one + * DNS blacklisting + * DKIM and ARC validation and signing + * DMARC validation + * SPF validation + + + +It also has a nice web UI: + +![rspamd web ui status][5] + +rspamd web ui status + +![rspamd web ui investigating a spam message][6] + +rspamd web ui investigating a spam message + +Setting up rspamd is quite easy. You basically just drop a bunch of configuration overrides into `/etc/rspamd/local.d` and you’re done. Heck, it mostly works out of the box. There’s a fancy `rspamadm configwizard` too. + +What you do want for rspamd is a redis server. redis is needed in [many places][7], such as rate limiting, greylisting, dmarc, reply tracking, ip scoring, neural networks. + +I made a few changes to the defaults: + + * I enabled subject rewriting instead of adding headers, so spam mail subjects get `[SPAM]` prepended, in `local.d/actions.conf`: + +``` + reject = 15; +rewrite_subject = 6; +add_header = 6; +greylist = 4; +subject = "[SPAM] %s"; +``` + + * I set `autolearn = true;` in `local.d/classifier-bayes.conf` to make it learn that an email that has a score of at least 15 (those that are rejected) is spam, and emails with negative scores are ham. + + * I set `extended_spam_headers = true;` in `local.d/milter_headers.conf` to get a report from rspamd in the header seeing the score and how the score came to be. + + + + +### ARC setup + +[ARC][8] is the ‘Authenticated Received Chain’ and is currently a DMARC working group work item. It allows forwarders / mailing lists to authenticate their forwarding of the emails and the checks they have performed. + +rspamd is capable of validating and signing emails with ARC, but I’m not sure how much influence ARC has on gmail at the moment, for example. + +There are three parts to setting up ARC: + + 1. Generate a DKIM key pair (use `rspamadm dkim_keygen`) + 2. Setup rspamd to sign incoming emails using the private key + 3. Add a DKIM `TXT` record for the public key. `rspamadm` helpfully tells you how it looks like. + + + +For step two, what we need to do is configure `local.d/arc.conf`. You can basically use the example configuration from the [rspamd page][9], the key point for signing incoming email is to specifiy `sign_incoming = true;` and `use_domain_sign_inbound = "recipient";` (FWIW, none of these options are documented, they are fairly new, and nobody updated the documentation for them). + +My configuration looks like this at the moment: + +``` +# If false, messages with empty envelope from are not signed +allow_envfrom_empty = true; +# If true, envelope/header domain mismatch is ignored +allow_hdrfrom_mismatch = true; +# If true, multiple from headers are allowed (but only first is used) +allow_hdrfrom_multiple = false; +# If true, username does not need to contain matching domain +allow_username_mismatch = false; +# If false, messages from authenticated users are not selected for signing +auth_only = true; +# Default path to key, can include '$domain' and '$selector' variables +path = "${DBDIR}/arc/$domain.$selector.key"; +# Default selector to use +selector = "arc"; +# If false, messages from local networks are not selected for signing +sign_local = true; +# +sign_inbound = true; +# Symbol to add when message is signed +symbol_signed = "ARC_SIGNED"; +# Whether to fallback to global config +try_fallback = true; +# Domain to use for ARC signing: can be "header" or "envelope" +use_domain = "header"; +use_domain_sign_inbound = "recipient"; +# Whether to normalise domains to eSLD +use_esld = true; +# Whether to get keys from Redis +use_redis = false; +# Hash for ARC keys in Redis +key_prefix = "ARC_KEYS"; +``` + +This would also sign any outgoing email, but I’m not sure that’s necessary - my understanding is that we only care about ARC when forwarding/receiving incoming emails, not when sending them (at least that’s what gmail does). + +### Other Issues + +There are few other things to keep in mind when running your own mail server. I probably don’t know them all yet, but here we go: + + * You must have a fully qualified hostname resolving to a public IP address + + * Your public IP address must resolve back to the fully qualified host name + + * Again, you should run a recursive DNS resolver so your DNS blacklists work (thanks waldi for pointing that out) + + * Setup an SPF record. Mine looks like this: + +`jak-linux.org. 3600 IN TXT "v=spf1 +mx ~all"` + +this states that all my mail servers may send email, but others probably should not (a softfail). Not having an SPF record can punish you; for example, rspamd gives missing SPF and DKIM a score of 1. + + * All of that software is sandboxed using AppArmor. Makes you question its security a bit less! + + + + +### Source code, outlook + +As always, you can find the Ansible roles on [GitHub][10]. Feel free to point out bugs! 😉 + +In the next installment of this series, we will be looking at setting up Dovecot, and configuring DKIM. We probably also want to figure out how to run notmuch on the server, keep messages in matching maildirs, and have my laptop synchronize the maildir and notmuch state with the server. Ugh, sounds like a lot of work. + +-------------------------------------------------------------------------------- + +via: https://blog.jak-linux.org/2019/01/05/setting-up-an-email-server-part1/ + +作者：[Julian Andres Klode][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://blog.jak-linux.org/ +[b]: https://github.com/lujun9972 +[1]: http://www.postfix.org/ +[2]: https://rspamd.com/ +[3]: https://www.isc.org/downloads/bind/ +[4]: https://github.com/roehling/postsrsd +[5]: https://blog.jak-linux.org/2019/01/05/setting-up-an-email-server-part1/rspamd-status.png +[6]: https://blog.jak-linux.org/2019/01/05/setting-up-an-email-server-part1/rspamd-spam.png +[7]: https://rspamd.com/doc/configuration/redis.html +[8]: http://arc-spec.org/ +[9]: https://rspamd.com/doc/modules/arc.html +[10]: https://github.com/julian-klode/ansible.jak-linux.org diff --git a/sources/tech/20190107 Aliases- To Protect and Serve.md b/sources/tech/20190107 Aliases- To Protect and Serve.md new file mode 100644 index 0000000000..783c59dc41 --- /dev/null +++ b/sources/tech/20190107 Aliases- To Protect and Serve.md @@ -0,0 +1,176 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Aliases: To Protect and Serve) +[#]: via: (https://www.linux.com/blog/learn/2019/1/aliases-protect-and-serve) +[#]: author: (Paul Brown https://www.linux.com/users/bro66) + +Aliases: To Protect and Serve +====== + +![](https://www.linux.com/sites/lcom/files/styles/rendered_file/public/prairie-path_1920.jpg?itok=wRARsM7p) + +Happy 2019! Here in the new year, we’re continuing our series on aliases. By now, you’ve probably read our [first article on aliases][1], and it should be quite clear how they are the easiest way to save yourself a lot of trouble. You already saw, for example, that they helped with muscle-memory, but let's see several other cases in which aliases come in handy. + +### Aliases as Shortcuts + +One of the most beautiful things about Linux's shells is how you can use zillions of options and chain commands together to carry out really sophisticated operations in one fell swoop. All right, maybe beauty is in the eye of the beholder, but let's agree that this feature published practical. + +The downside is that you often come up with recipes that are often hard to remember or cumbersome to type. Say space on your hard disk is at a premium and you want to do some New Year's cleaning. Your first step may be to look for stuff to get rid off in you home directory. One criteria you could apply is to look for stuff you don't use anymore. `ls` can help with that: + +``` +ls -lct +``` + +The instruction above shows the details of each file and directory (`-l`) and also shows when each item was last accessed (`-c`). It then orders the list from most recently accessed to least recently accessed (`-t`). + +Is this hard to remember? You probably don’t use the `-c` and `-t` options every day, so perhaps. In any case, defining an alias like + +``` +alias lt='ls -lct' +``` + +will make it easier. + +Then again, you may want to have the list show the oldest files first: + +``` +alias lo='lt -F | tac' +``` + +![aliases][3] + +Figure 1: The lt and lo aliases in action. + +[Used with permission][4] + +There are a few interesting things going here. First, we are using an alias (`lt`) to create another alias -- which is perfectly okay. Second, we are passing a new parameter to `lt` (which, in turn gets passed to `ls` through the definition of the `lt` alias). + +The `-F` option appends special symbols to the names of items to better differentiate regular files (that get no symbol) from executable files (that get an `*`), files from directories (end in `/`), and all of the above from links, symbolic and otherwise (that end in an `@` symbol). The `-F` option is throwback to the days when terminals where monochrome and there was no other way to easily see the difference between items. You use it here because, when you pipe the output from `lt` through to `tac` you lose the colors from `ls`. + +The third thing to pay attention to is the use of piping. Piping happens when you pass the output from an instruction to another instruction. The second instruction can then use that output as its own input. In many shells (including Bash), you pipe something using the pipe symbol (`|`). + +In this case, you are piping the output from `lt -F` into `tac`. `tac`'s name is a bit of a joke. You may have heard of `cat`, the instruction that was nominally created to con _cat_ enate files together, but that in practice is used to print out the contents of a file to the terminal. `tac` does the same, but prints out the contents it receives in reverse order. Get it? `cat` and `tac`. Developers, you so funny! + +The thing is both `cat` and `tac` can also print out stuff piped over from another instruction, in this case, a list of files ordered chronologically. + +So... after that digression, what comes out of the other end is the list of files and directories of the current directory in inverse order of freshness. + +The final thing you have to bear in mind is that, while `lt` will work the current directory and any other directory... + +``` +# This will work: +lt +# And so will this: +lt /some/other/directory +``` + +... `lo` will only work with the current directory: + +``` +# This will work: +lo +# But this won't: +lo /some/other/directory +``` + +This is because Bash expands aliases into their components. When you type this: + +``` +lt /some/other/directory +``` + +Bash REALLY runs this: + +``` +ls -lct /some/other/directory +``` + +which is a valid Bash command. + +However, if you type this: + +``` +lo /some/other/directory +``` + +Bash tries to run this: + +``` +ls -lct -F | tac /some/other/directory +``` + +which is not a valid instruction, because `tac` mainly because _/some/other/directory_ is a directory, and `cat` and `tac` don't do directories. + +### More Alias Shortcuts + + * `alias lll='ls -R'` prints out the contents of a directory and then drills down and prints out the contents of its subdirectories and the subdirectories of the subdirectories, and so on and so forth. It is a way of seeing everything you have under a directory. + + * `mkdir='mkdir -pv'` let's you make directories within directories all in one go. With the base form of `mkdir`, to make a new directory containing a subdirectory you have to do this: + +``` + mkdir newdir +mkdir newdir/subdir +``` + +Or this: + +``` +mkdir -p newdir/subdir +``` + +while with the alias you would only have to do this: + +``` +mkdir newdir/subdir +``` + +Your new `mkdir` will also tell you what it is doing while is creating new directories. + + + + +### Aliases as Safeguards + +The other thing aliases are good for is as safeguards against erasing or overwriting your files accidentally. At this stage you have probably heard the legendary story about the new Linux user who ran: + +``` +rm -rf / +``` + +as root, and nuked the whole system. Then there's the user who decided that: + +``` +rm -rf /some/directory/ * +``` + +was a good idea and erased the complete contents of their home directory. Notice how easy it is to overlook that space separating the directory path and the `*`. + +Both things can be avoided with the `alias rm='rm -i'` alias. The `-i` option makes `rm` ask the user whether that is what they really want to do and gives you a second chance before wreaking havoc in your file system. + +The same goes for `cp`, which can overwrite a file without telling you anything. Create an alias like `alias cp='cp -i'` and stay safe! + +### Next Time + +We are moving more and more into scripting territory. Next time, we'll take the next logical step and see how combining instructions on the command line gives you really interesting and sophisticated solutions to everyday admin problems. + + +-------------------------------------------------------------------------------- + +via: https://www.linux.com/blog/learn/2019/1/aliases-protect-and-serve + +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/blog/learn/2019/1/aliases-protect-and-serve +[2]: https://www.linux.com/files/images/fig01png-0 +[3]: https://www.linux.com/sites/lcom/files/styles/rendered_file/public/fig01_0.png?itok=crqTm_va (aliases) +[4]: https://www.linux.com/licenses/category/used-permission diff --git a/sources/tech/20190107 Different Ways To Update Linux Kernel For Ubuntu.md b/sources/tech/20190107 Different Ways To Update Linux Kernel For Ubuntu.md new file mode 100644 index 0000000000..32a6a7dd3e --- /dev/null +++ b/sources/tech/20190107 Different Ways To Update Linux Kernel For Ubuntu.md @@ -0,0 +1,232 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Different Ways To Update Linux Kernel For Ubuntu) +[#]: via: (https://www.ostechnix.com/different-ways-to-update-linux-kernel-for-ubuntu/) +[#]: author: (SK https://www.ostechnix.com/author/sk/) + +Different Ways To Update Linux Kernel For Ubuntu +====== + +![](https://www.ostechnix.com/wp-content/uploads/2019/01/ubuntu-linux-kernel-720x340.png) + +In this guide, we have given 7 different ways to update Linux kernel for Ubuntu. Among the 7 methods, five methods requires system reboot to apply the new Kernel and two methods don’t. Before updating Linux Kernel, it is **highly recommended to backup your important data!** All methods mentioned here are tested on Ubuntu OS only. We are not sure if they will work on other Ubuntu flavors (Eg. Xubuntu) and Ubuntu derivatives (Eg. Linux Mint). + +### Part A – Kernel Updates with reboot + +The following methods requires you to reboot your system to apply the new Linux Kernel. All of the following methods are recommended for personal or testing systems. Again, please backup your important data, configuration files and any other important stuff from your Ubuntu system. + +#### Method 1 – Update the Linux Kernel with dpkg (The manual way) + +This method helps you to manually download and install the latest available Linux kernel from **[kernel.ubuntu.com][1]** website. If you want to install most recent version (either stable or release candidate), this method will help. Download the Linux kernel version from the above link. As of writing this guide, the latest available version was **5.0-rc1** and latest stable version was **v4.20**. + +![][3] + +Click on the Linux Kernel version link of your choice and find the section for your architecture (‘Build for XXX’). In that section, download the two files with these patterns (where X.Y.Z is the highest version): + + 1. linux-image-*X.Y.Z*-generic-*.deb + 2. linux-modules-X.Y.Z*-generic-*.deb + + + +In a terminal, change directory to where the files are and run this command to manually install the kernel: + +``` +$ sudo dpkg --install *.deb +``` + +Reboot to use the new kernel: + +``` +$ sudo reboot +``` + +Check the kernel is as expected: + +``` +$ uname -r +``` + +For step by step instructions, please check the section titled under “Install Linux Kernel 4.15 LTS On DEB based systems” in the following guide. + ++ [Install Linux Kernel 4.15 In RPM And DEB Based Systems](https://www.ostechnix.com/install-linux-kernel-4-15-rpm-deb-based-systems/) + +The above guide is specifically written for 4.15 version. However, all the steps are same for installing latest versions too. + +**Pros:** No internet needed (You can download the Linux Kernel from any system). + +**Cons:** Manual update. Reboot necessary. + +#### Method 2 – Update the Linux Kernel with apt-get (The recommended method) + +This is the recommended way to install latest Linux kernel on Ubuntu-like systems. Unlike the previous method, this method will download and install latest Kernel version from Ubuntu official repositories instead of **kernel.ubuntu.com** website.. + +To update the whole system including the Kernel, just do: + +``` +$ sudo apt-get update + +$ sudo apt-get upgrade +``` + +If you want to update the Kernel only, run: + +``` +$ sudo apt-get upgrade linux-image-generic +``` + +**Pros:** Simple. Recommended method. + +**Cons:** Internet necessary. Reboot necessary. + +Updating Kernel from official repositories will mostly work out of the box without any problems. If it is the production system, this is the recommended way to update the Kernel. + +Method 1 and 2 requires user intervention to update Linux Kernels. The following methods (3, 4 & 5) are mostly automated. + +#### Method 3 – Update the Linux Kernel with Ukuu + +**Ukuu** is a Gtk GUI and command line tool that downloads the latest main line Linux kernel from **kernel.ubuntu.com** , and install it automatically in your Ubuntu desktop and server editions. Ukku is not only simplifies the process of manually downloading and installing new Kernels, but also helps you to safely remove the old and unnecessary Kernels. For more details, refer the following guide. + ++ [Ukuu – An Easy Way To Install And Upgrade Linux Kernel In Ubuntu-based Systems](https://www.ostechnix.com/ukuu-an-easy-way-to-install-and-upgrade-linux-kernel-in-ubuntu-based-systems/) + +**Pros:** Easy to install and use. Automatically installs main line Kernel. + +**Cons:** Internet necessary. Reboot necessary. + +#### Method 4 – Update the Linux Kernel with UKTools + +Just like Ukuu, the **UKTools** also fetches the latest stable Kernel from from **kernel.ubuntu.com** site and installs it automatically on Ubuntu and its derivatives like Linux Mint. More details about UKTools can be found in the link given below. + ++ [UKTools – Upgrade Latest Linux Kernel In Ubuntu And Derivatives](https://www.ostechnix.com/uktools-upgrade-latest-linux-kernel-in-ubuntu-and-derivatives/) + +**Pros:** Simple. Automated. + +**Cons:** Internet necessary. Reboot necessary. + +#### Method 5 – Update the Linux Kernel with Linux Kernel Utilities + +**Linux Kernel Utilities** is yet another program that makes the process of updating Linux kernel easy in Ubuntu-like systems. It is actually a set of BASH shell scripts used to compile and/or update latest Linux kernels for Debian and derivatives. It consists of three utilities, one for manually compiling and installing Kernel from source from [**http://www.kernel.org**][4] website, another for downloading and installing pre-compiled Kernels from from **** website. and third script is for removing the old kernels. For more details, please have a look at the following link. + ++ [Linux Kernel Utilities – Scripts To Compile And Update Latest Linux Kernel For Debian And Derivatives](https://www.ostechnix.com/linux-kernel-utilities-scripts-compile-update-latest-linux-kernel-debian-derivatives/) + +**Pros:** Simple. Automated. + +**Cons:** Internet necessary. Reboot necessary. + + +### Part B – Kernel Updates without reboot + +As I already said, all of above methods need you to reboot the server before the new kernel is active. If they are personal systems or testing machines, you could simply reboot and start using the new Kernel. But, what if they are production systems that requires zero downtime? No problem. This is where **Livepatching** comes in handy! + +The **livepatching** (or hot patching) allows you to install Linux updates or patches without rebooting, keeping your server at the latest security level, without any downtime. This is attractive for ‘always-on’ servers, such as web hosts, gaming servers, in fact, any situation where the server needs to stay on all the time. Linux vendors maintain patches only for security fixes, so this approach is best when security is your main concern. + +The following two methods doesn’t require system reboot and useful for updating Linux Kernel on production and mission-critical Ubuntu servers. + +#### Method 6 – Update the Linux Kernel Canonical Livepatch Service + +![][5] + +[**Canonical Livepatch Service**][6] applies Kernel updates, patches and security hotfixes automatically without rebooting the Ubuntu systems. It reduces the Ubuntu systems downtime and keep them secure. Canonical Livepatch Service can be set up either during or after installation. If you are using desktop Ubuntu, the Software Updater will automatically check for kernel patches and notify you. In a console-based system, it is up to you to run apt-get update regularly. It will install kernel security patches only when you run the command “apt-get upgrade”, hence is semi-automatic. + +Livepatch is free for three systems. If you have more than three, you need to upgrade to enterprise support solution named **Ubuntu Advantage** suite. This suite includes **Kernel Livepatching** and other services such as, + + * Extended Security Maintenance – critical security updates after Ubuntu end-of-life. + * Landscape – the systems management tool for using Ubuntu at scale. + * Knowledge Base – A private collection of articles and tutorials written by Ubuntu experts. + * Phone and web-based support. + + + +**Cost** + +Ubuntu Advantage includes three paid plans namely, Essential, Standard and Advanced. The basic plan (Essential plan) starts from **225 USD per year for one physical node** and **75 USD per year for one VPS**. It seems there is no monthly subscription for Ubuntu servers and desktops. You can view detailed information on all plans [**here**][7]. + +**Pros:** Simple. Semi-automatic. No reboot necessary. Free for 3 systems. + +**Cons:** Expensive for 4 or more hosts. No patch rollback. + +**Enable Canonical Livepatch Service** + +If you want to setup Livepatch service after installation, just do the following steps. + +Get a key at [**https://auth.livepatch.canonical.com/**][8]. + +``` +$ sudo snap install canonical-livepatch + +$ sudo canonical-livepatch enable your-key +``` + +#### Method 7 – Update the Linux Kernel with KernelCare + +![][9] + +[**KernelCare**][10] is the newest of all the live patching solutions. It is the product of [CloudLinux][11]. KernelCare runs on Ubuntu and other flavors of Linux. It checks for patch releases every 4 hours and will install them without confirmation. Patches can be rolled back if there are problems. + +**Cost** + +Fees, per server: **4 USD per month** , **45 USD per year**. + +Compared to Ubuntu Livepatch, kernelCare seems very cheap and affordable. Good thing is **monthly subscriptions are also available**. Another notable feature is it supports other Linux distributions, such as Red Hat, CentOS, Debian, Oracle Linux, Amazon Linux and virtualization platforms like OpenVZ, Proxmox etc. + +You can read all the features and benefits of KernelCare [**here**][12] and check all available plan details [**here**][13]. + +**Pros:** Simple. Fully automated. Wide OS coverage. Patch rollback. No reboot necessary. Free license for non-profit organizations. Low cost. + +**Cons:** Not free (except for 30 day trial). + +**Enable KernelCare Service** + +Get a 30-day trial key at [**https://cloudlinux.com/kernelcare-free-trial5**][14]. + +Run the following commands to enable KernelCare and register the key. + +``` +$ sudo wget -qq -O - https://repo.cloudlinux.com/kernelcare/kernelcare_install.sh | bash + +$ sudo /usr/bin/kcarectl --register KEY +``` + +If you’re looking for an affordable and reliable commercial service to keep the Linux Kernel updated on your Linux servers, KernelCare is good to go. + +*with inputs from **Paul A. Jacobs** , a Technical Evangelist and Content Writer from Cloud Linux.* + +**Suggested read:** + +And, that’s all for now. Hope this was useful. If you believe any other tools/methods should include in this list, feel free to let us know in the comment section below. I will check and update this guide accordingly. + +More good stuffs to come. Stay tuned! + +Cheers! + + + +-------------------------------------------------------------------------------- + +via: https://www.ostechnix.com/different-ways-to-update-linux-kernel-for-ubuntu/ + +作者：[SK][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.ostechnix.com/author/sk/ +[b]: https://github.com/lujun9972 +[1]: http://kernel.ubuntu.com/~kernel-ppa/mainline/ +[2]: data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7 +[3]: http://www.ostechnix.com/wp-content/uploads/2019/01/Ubuntu-mainline-kernel.png +[4]: http://www.kernel.org +[5]: http://www.ostechnix.com/wp-content/uploads/2019/01/Livepatch.png +[6]: https://www.ubuntu.com/livepatch +[7]: https://www.ubuntu.com/support/plans-and-pricing +[8]: https://auth.livepatch.canonical.com/ +[9]: http://www.ostechnix.com/wp-content/uploads/2019/01/KernelCare.png +[10]: https://www.kernelcare.com/ +[11]: https://www.cloudlinux.com/ +[12]: https://www.kernelcare.com/update-kernel-linux/ +[13]: https://www.kernelcare.com/pricing/ +[14]: https://cloudlinux.com/kernelcare-free-trial5 diff --git a/sources/tech/20190107 DriveSync - Easy Way to Sync Files Between Local And Google Drive from Linux CLI.md b/sources/tech/20190107 DriveSync - Easy Way to Sync Files Between Local And Google Drive from Linux CLI.md new file mode 100644 index 0000000000..6552cc3905 --- /dev/null +++ b/sources/tech/20190107 DriveSync - Easy Way to Sync Files Between Local And Google Drive from Linux CLI.md @@ -0,0 +1,239 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (DriveSync – Easy Way to Sync Files Between Local And Google Drive from Linux CLI) +[#]: via: (https://www.2daygeek.com/drivesync-google-drive-sync-client-for-linux/) +[#]: author: (Magesh Maruthamuthu https://www.2daygeek.com/author/magesh/) + +DriveSync – Easy Way to Sync Files Between Local And Google Drive from Linux CLI +====== + +Google Drive is an one of the best cloud storage compared with other cloud storage. + +It’s one of the application which is used by millions of users in daily basics. + +It allow users to access the application anywhere irrespective of devices. + +We can upload, download & share documents, photo, files, docs, spreadsheet, etc to anyone with securely. + +We had already written few articles in 2daygeek website about google drive mapping with Linux. + +If you would like to check those, navigate to the following link. + +GNOME desktop offers easy way to **[Integrate Google Drive Using Gnome Nautilus File Manager in Linux][1]** without headache. + +Also, you can give a try with **[Google Drive Ocamlfuse Client][2]**. + +### What’s DriveSync? + +[DriveSync][3] is a command line utility that synchronizes your files between local system and Google Drive via command line. + +Downloads new remote files, uploads new local files to your Drive and deletes or updates files both locally and on Drive if they have changed in one place. + +Allows blacklisting or whitelisting of files and folders that should not / should be synced. + +It was written in Ruby scripting language so, make sure your system should have ruby installed. If it’s not installed then install it as a prerequisites for DriveSync. + +### DriveSync Features + + * Downloads new remote files + * Uploads new local files + * Delete or Update files in both locally and Drive + * Allow blacklist to disable sync for files and folders + * Automate the sync using cronjob + * Allow us to set file upload/download size (Defautl 512MB) + * Allow us to modify Timeout threshold + + + +### How to Install Ruby Scripting Language in Linux? + +Ruby is an interpreted scripting language for quick and easy object-oriented programming. It has many features to process text files and to do system management tasks (like in Perl). It is simple, straight-forward, and extensible. + +It’s available in all the Linux distribution official repository. Hence we can easily install it with help of distribution official **[Package Manager][4]**. + +For **`Fedora`** system, use **[DNF Command][5]** to install Ruby. + +``` +$ sudo dnf install ruby rubygem-bundler +``` + +For **`Debian/Ubuntu`** systems, use **[APT-GET Command][6]** or **[APT Command][7]** to install Ruby. + +``` +$ sudo apt install ruby ruby-bundler +``` + +For **`Arch Linux`** based systems, use **[Pacman Command][8]** to install Ruby. + +``` +$ sudo pacman -S ruby ruby-bundler +``` + +For **`RHEL/CentOS`** systems, use **[YUM Command][9]** to install Ruby. + +``` +$ sudo yum install ruby ruby-bundler +``` + +For **`openSUSE Leap`** system, use **[Zypper Command][10]** to install Ruby. + +``` +$ sudo zypper install ruby ruby-bundler +``` + +### How to Install DriveSync in Linux? + +DriveSync installation also easy to do it. Follow the below procedure to get it done. + +``` +$ git clone https://github.com/MStadlmeier/drivesync.git +$ cd drivesync/ +$ bundle install +``` + +### How to Set Up DriveSync in Linux? + +As of now, we had successfully installed DriveSync and still we need to perform few steps to use this. + +Run the following command to set up this and Sync the files. + +``` +$ ruby drivesync.rb +``` + +When you ran the above command you will be getting the below url. +![][12] + +Navigate to the given URL in your preferred Web Browser and follow the instruction. It will open a google sign-in page in default web browser. Enter your credentials then hit Sign in button. +![][13] + +Input your password. +![][14] + +Hit **`Allow`** button to allow DriveSync to access your Google Drive. +![][15] + +Finally, it will give you an authorization code. +![][16] + +Just copy and past it on the terminal and hit **`Enter`** button to start the sync. +![][17] + +Yes, it’s syncing the files from Google Drive to my local folder. + +``` +$ ruby drivesync.rb +Warning: Could not find config file at /home/daygeek/.drivesync/config.yml . Creating default config... +Open the following URL in the browser and enter the resulting code after authorization +https://accounts.google.com/o/oauth2/auth?access_type=offline&approval_prompt=force&client_id=xxxxxxxxxxxxxxxxxxxxxxxxxxxx.apps.googleusercontent.com&include_granted_scopes=true&redirect_uri=urn:ietf:wg:oauth:2.0:oob&response_type=code&scope=https://www.googleapis.com/auth/drive +4/ygAxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx +Local folder is 1437 files behind and 0 files ahead of remote +Starting sync at 2019-01-06 19:48:49 +0530 +Downloading file 2018-07-31-17-48-54-635_1533039534635_XXXPM0534X_ITRV.zip ... +Downloading file 5459XXXXXXXXXX25_11-03-2018.PDF ... +Downloading file 2g-image-design/new-design-28-Mar-2018/new-base-format-icon-theme.svg ... +Downloading file 2g-image-design/new-design-28-Mar-2018/2g-banner-format.svg ... +Downloading file 2g-image-design/new-design-28-Mar-2018/new-base-format.svg ... +Downloading file documents/Magesh_Resume_Updated_26_Mar_2018.doc ... +Downloading file documents/Magesh_Resume_updated-new.doc ... +Downloading file documents/Aadhaar-Thanu.PNG ... +Downloading file documents/Aadhaar-Magesh.PNG ... +Downloading file documents/Copy of PP-docs.pdf ... +Downloading file EAadhaar_2189821080299520170807121602_25082017123052_172991.pdf ... +Downloading file Tanisha/VID_20170223_113925.mp4 ... +Downloading file Tanisha/VID_20170224_073234.mp4 ... +Downloading file Tanisha/VID_20170304_170457.mp4 ... +Downloading file Tanisha/IMG_20170225_203243.jpg ... +Downloading file Tanisha/IMG_20170226_123949.jpg ... +Downloading file Tanisha/IMG_20170226_123953.jpg ... +Downloading file Tanisha/IMG_20170304_184227.jpg ... +. +. +. +Sync complete. +``` + +It will create the **`drive`** folder under **`/home/user/Documents/`** and sync all the files in it. +![][18] + +DriveSync configuration files are located in the following location **`/home/user/.drivesync/`** if you had installed it on your **home** directory. + +``` +$ ls -lh ~/.drivesync/ +total 176K +-rw-r--r-- 1 daygeek daygeek 1.9K Jan 6 19:42 config.yml +-rw-r--r-- 1 daygeek daygeek 170K Jan 6 21:31 manifest +``` + +You can make your changes by modifying the **`config.yml`** file. + +### How to Verify Whether Sync is Working Fine or Not? + +To test this, we are going to create a new folder called **`2g-docs-2019`**. Also, adding an image file in it. Once it’s done, run the **`drivesync.rb`** command again. + +``` +$ ruby drivesync.rb +Local folder is 0 files behind and 1 files ahead of remote +Starting sync at 2019-01-06 21:59:32 +0530 +Uploading file 2g-docs-2019/Asciinema - Record And Share Your Terminal Activity On The Web.png ... +``` + +Yes, it has been synced to Google Drive. The same has been verified through Web Browser. +![][19] + +Create the below **CronJob** to enable an auto sync. The following “CronJob” will be running an every mins. + +``` +$ vi crontab +*/1 core.md Dict.md lctt2014.md lctt2016.md lctt2018.md LICENSE published README.md scripts sources translated core.md Dict.md lctt2014.md lctt2016.md lctt2018.md LICENSE published README.md scripts sources translated core.md Dict.md lctt2014.md lctt2016.md lctt2018.md LICENSE published README.md scripts sources translated core.md Dict.md lctt2014.md lctt2016.md lctt2018.md LICENSE published README.md scripts sources translated ruby ~/drivesync/drivesync.rb +``` + +I have added one more file to test this. Yes, it got success. + +``` +Jan 07 09:36:01 daygeek-Y700 crond[590]: (daygeek) RELOAD (/var/spool/cron/daygeek) +Jan 07 09:36:01 daygeek-Y700 crond[20942]: pam_unix(crond:session): session opened for user daygeek by (uid=0) +Jan 07 09:36:01 daygeek-Y700 CROND[20943]: (daygeek) CMD (ruby ~/drivesync/drivesync.rb) +Jan 07 09:36:29 daygeek-Y700 CROND[20942]: (daygeek) CMDOUT (Local folder is 0 files behind and 1 files ahead of remote) +Jan 07 09:36:29 daygeek-Y700 CROND[20942]: (daygeek) CMDOUT (Starting sync at 2019-01-07 09:36:26 +0530) +Jan 07 09:36:29 daygeek-Y700 CROND[20942]: (daygeek) CMDOUT (Uploading file 2g-docs-2019/Check CPU And HDD Temperature In Linux.png ...) +Jan 07 09:36:29 daygeek-Y700 CROND[20942]: (daygeek) CMDOUT () +Jan 07 09:36:29 daygeek-Y700 CROND[20942]: (daygeek) CMDOUT (Sync complete.) +Jan 07 09:36:29 daygeek-Y700 CROND[20942]: pam_unix(crond:session): session closed for user daygeek +``` + +-------------------------------------------------------------------------------- + +via: https://www.2daygeek.com/drivesync-google-drive-sync-client-for-linux/ + +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/mount-access-setup-google-drive-in-linux/ +[2]: https://www.2daygeek.com/mount-access-google-drive-on-linux-with-google-drive-ocamlfuse-client/ +[3]: https://github.com/MStadlmeier/drivesync +[4]: https://www.2daygeek.com/category/package-management/ +[5]: https://www.2daygeek.com/dnf-command-examples-manage-packages-fedora-system/ +[6]: https://www.2daygeek.com/apt-get-apt-cache-command-examples-manage-packages-debian-ubuntu-systems/ +[7]: https://www.2daygeek.com/apt-command-examples-manage-packages-debian-ubuntu-systems/ +[8]: https://www.2daygeek.com/pacman-command-examples-manage-packages-arch-linux-system/ +[9]: https://www.2daygeek.com/yum-command-examples-manage-packages-rhel-centos-systems/ +[10]: https://www.2daygeek.com/zypper-command-examples-manage-packages-opensuse-system/ +[11]: data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7 +[12]: https://www.2daygeek.com/wp-content/uploads/2019/01/drivesync-easy-way-to-sync-files-between-local-and-google-drive-from-linux-cli-1.jpg +[13]: https://www.2daygeek.com/wp-content/uploads/2019/01/drivesync-easy-way-to-sync-files-between-local-and-google-drive-from-linux-cli-2.png +[14]: https://www.2daygeek.com/wp-content/uploads/2019/01/drivesync-easy-way-to-sync-files-between-local-and-google-drive-from-linux-cli-3.png +[15]: https://www.2daygeek.com/wp-content/uploads/2019/01/drivesync-easy-way-to-sync-files-between-local-and-google-drive-from-linux-cli-4.png +[16]: https://www.2daygeek.com/wp-content/uploads/2019/01/drivesync-easy-way-to-sync-files-between-local-and-google-drive-from-linux-cli-5.png +[17]: https://www.2daygeek.com/wp-content/uploads/2019/01/drivesync-easy-way-to-sync-files-between-local-and-google-drive-from-linux-cli-6.jpg +[18]: https://www.2daygeek.com/wp-content/uploads/2019/01/drivesync-easy-way-to-sync-files-between-local-and-google-drive-from-linux-cli-7.jpg +[19]: https://www.2daygeek.com/wp-content/uploads/2019/01/drivesync-easy-way-to-sync-files-between-local-and-google-drive-from-linux-cli-8.png diff --git a/sources/tech/20190107 Getting started with Pelican- A Python-based static site generator.md b/sources/tech/20190107 Getting started with Pelican- A Python-based static site generator.md new file mode 100644 index 0000000000..29772d473c --- /dev/null +++ b/sources/tech/20190107 Getting started with Pelican- A Python-based static site generator.md @@ -0,0 +1,223 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Getting started with Pelican: A Python-based static site generator) +[#]: via: (https://opensource.com/article/19/1/getting-started-pelican) +[#]: author: (Craig Sebenik https://opensource.com/users/craig5) + +Getting started with Pelican: A Python-based static site generator +====== +Pelican is a great choice for Python users who want to self-host a simple website or blog. + +![](https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/web-design-monitor-website.png?itok=yUK7_qR0) + +If you want to create a custom website or blog, you have a lot of options. Many providers will host your website and do much of the work for you. (WordPress is an extremely popular option.) But you lose some flexibility by using a hosted solution. As a software developer, I prefer to manage my own server and keep more freedom in how my website operates. + +However, it is a fair amount of work to manage a web server. Installing it and getting a simple application up to serve content is easy enough. But keeping on top of security patches and updates is very time-consuming. If you just want to serve static web pages, having a web server and a host of applications may be more effort than it's worth. Creating HTML pages by hand is also not a good option. + +This is where a static site generator can come in. These applications use templates to create all the static pages you want and cross-link them with associated metadata. (e.g., showing all the pages with a common tag or keyword.) Static site generators help you create a site with a common look and feel using elements like navigation areas and a header and footer. + +I have been using [Python][1] for years now. So, when I first started looking for something to generate static HTML pages, I wanted something written in Python. The main reason is that I often want to peek into the internals of how an application works, and using a language that I already know makes that easier. (If that isn't important to you or you don't use Python, there are some other great [static site generators][2] that use Ruby, JavaScript, and other languages.) + +I decided to give [Pelican][3] a try. It is a commonly used static site generator written in Python. It directly supports [reStructuredText][4] and can support [Markdown][5] when the required package is installed. All the tasks are performed via command-line interface (CLI) tools, which makes it simple for anyone familiar with the command line. And its simple quickstart CLI tool makes creating a website extremely easy. + +In this article, I'll explain how to install Pelican 4, add an article, and change the default theme. (Note: This was all developed on MacOS; it should work the same using any flavor of Unix/Linux, but I don't have a Windows host to test on.) + +### Installation and configuration + +The first step is to create a [virtualenv][6] and install Pelican. + +``` +$ mkdir test-site +$ cd test-site +$ python3 -m venv venv +$ ./venv/bin/pip install --upgrade pip +... +Successfully installed pip-18.1 +$ ./venv/bin/pip install pelican +Collecting pelican +... +Successfully installed MarkupSafe-1.1.0 blinker-1.4 docutils-0.14 feedgenerator-1.9 jinja2-2.10 pelican-4.0.1 pygments-2.3.1 python-dateutil-2.7.5 pytz-2018.7 six-1.12.0 unidecode-1.0.23 +``` + +To keep things simple, I entered values for the title and author and replied N to URL prefix and article pagination. (For the rest of the questions, I used the default given.) + +Pelican's quickstart CLI tool will create the basic layout and a few files to get you started. Run the **pelican-quickstart** command. To keep things simple, I entered values for the **title** and **author** and replied **N** to URL prefix and article pagination. It is very easy to change these settings in the configuration file later. + +``` +$ ./venv/bin/pelicanquickstart +Welcome to pelicanquickstart v4.0.1. + +This script will help you create a new Pelican-based website. + +Please answer the following questions so this script can generate the files needed by Pelican. + +> Where do you want to create your new web site? [.] +> What will be the title of this web site? My Test Blog +> Who will be the author of this web site? Craig +> What will be the default language of this web site? [en] +> Do you want to specify a URL prefix? e.g., https://example.com (Y/n) n +> Do you want to enable article pagination? (Y/n) n +> What is your time zone? [Europe/Paris] +> Do you want to generate a tasks.py/Makefile to automate generation and publishing? (Y/n) +> Do you want to upload your website using FTP? (y/N) +> Do you want to upload your website using SSH? (y/N) +> Do you want to upload your website using Dropbox? (y/N) +> Do you want to upload your website using S3? (y/N) +> Do you want to upload your website using Rackspace Cloud Files? (y/N) +> Do you want to upload your website using GitHub Pages? (y/N) +Done. Your new project is available at /Users/craig/tmp/pelican/test-site +``` + +All the files you need to get started are ready to go. + +The quickstart defaults to the Europe/Paris time zone, so change that before proceeding. Open the **pelicanconf.py** file in your favorite text editor. Look for the **TIMEZONE** variable. + +``` +TIMEZONE = 'Europe/Paris' +``` + +Change it to **UTC**. + +``` +TIMEZONE = 'UTC' +``` + +To update the social settings, look for the **SOCIAL** variable in **pelicanconf.py**. + +``` +SOCIAL = (('You can add links in your config file', '#'), +          ('Another social link', '#'),) +``` + +I'll add a link to my Twitter account. + +``` +SOCIAL = (('Twitter (#craigs55)', 'https://twitter.com/craigs55'),) +``` + +Notice that trailing comma—it's important. That comma helps Python recognize the variable is actually a set. Make sure you don't delete that comma. + +Now you have the basics of a site. The quickstart created a Makefile with a number of targets. Giving the **devserver** target to **make** will start a development server on your machine so you can preview everything. The CLI commands used in the Makefile are assumed to be part of your **PATH** , so you need to **activate** the **virtualenv** first. + +``` +$ source ./venv/bin/activate +$ make devserver +pelican -lr /Users/craig/tmp/pelican/test-site/content o +/Users/craig/tmp/pelican/test-site/output -s /Users/craig/tmp/pelican/test-site/pelicanconf.py + +-> Modified: theme, settings. regenerating... +WARNING: No valid files found in content for the active readers: +   | BaseReader (static) +   | HTMLReader (htm, html) +   | RstReader (rst) +Done: Processed 0 articles, 0 drafts, 0 pages, 0 hidden pages and 0 draft pages in 0.18 seconds. +``` + +Point your favorite browser to to see your simple test blog. + +![](https://opensource.com/sites/default/files/uploads/pelican_test-site1.png) + +You can see the Twitter link on the right side and some links to Pelican, Python, and Jinja to the left of it. (Jinja is a great templating language that Pelican can use. You can learn more about it in [Jinja's documentation][7].) + +### Adding content + +Now that you have a basic site, add some content. First, add a file called **welcome.rst** to the site's **content** directory. In your favorite text editor, create a file with the following text: + +``` +$ pwd +/Users/craig/tmp/pelican/test-site +$ cat content/welcome.rst + +Welcome to my blog! +################### + +:date: 20181216 08:30 +:tags: welcome +:category: Intro +:slug: welcome +:author: Craig +:summary: Welcome document + +Welcome to my blog. +This is a short page just to show how to put up a static page. +``` + +The metadata lines—date, tags, etc.—are automatically parsed by Pelican. + +After you write the file, the **devserver** should output something like this: + +``` +-> Modified: content. regenerating... +Done: Processed 1 article, 0 drafts, 0 pages, 0 hidden pages and 0 draft pages in 0.10 seconds. +``` + +Reload your test site in your browser to view the changes. + +![](https://opensource.com/sites/default/files/uploads/pelican_test-site2.png) + +The metadata (e.g., date and tags) were automatically added to the page. Also, Pelican automatically detected the **intro** category and added the section to the top navigation. + +### Change the theme + +One of the nicest parts of working with popular, open source software like Pelican is that many users will make changes and contribute them back to the project. Many of the contributions are in the form of themes. + +A site's theme sets colors, layout options, etc. It's really easy to try out new themes. You can preview many of them at [Pelican Themes][8]. + +First, clone the GitHub repo: + +``` +$ cd .. +$ git clone --recursive https://github.com/getpelican/pelicanthemes +Cloning into 'pelicanthemes'... +``` + +Since I like the color blue, I'll try [blueidea][9]. + +Edit **pelicanconf.py** and add the following line: + +``` +THEME = '/Users/craig/tmp/pelican/pelican-themes/blueidea/' +``` + +The **devserver** will regenerate your output. Reload the webpage in your browser to see the new theme. + +![](https://opensource.com/sites/default/files/uploads/pelican_test-site3.png) + +The theme controls many aspects of the layout. For example, in the default theme, you can see the category (Intro) with the meta tags next to the article. But that category is not displayed in the blueidea theme. + +### Other considerations + +This was a pretty quick introduction to Pelican. There are a couple of important topics that I did not cover. + +First, one reason I was hesitant to move to a static site was that it wouldn't allow discussions on the articles. Fortunately, there are some third-party providers that will host discussions for you. The one I am currently looking at is [Disqus][10]. + +Next, everything above was done on my local machine. If I want others to view my site, I'll have to upload the pre-generated HTML files somewhere. If you look at the **pelican-quickstart** output, you will see options for using FTP, SSH, S3, and even GitHub Pages. Each option has its pros and cons. But, if I had to choose one, I would likely publish to GitHub Pages. + +Pelican has many other features—I am still learning more about it every day. If you want to self-host a website or a blog with simple, static content and you want to use Python, Pelican is a great choice. It has an active user community that is fixing bugs, adding features, and creating new and interesting themes. Give it a try! + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/19/1/getting-started-pelican + +作者：[Craig Sebenik][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/craig5 +[b]: https://github.com/lujun9972 +[1]: https://opensource.com/resources/python +[2]: https://opensource.com/sitewide-search?search_api_views_fulltext=static%20site%20generator +[3]: http://docs.getpelican.com/en/stable/ +[4]: http://docutils.sourceforge.net/rst.html +[5]: https://daringfireball.net/projects/markdown/ +[6]: https://virtualenv.pypa.io/en/latest/ +[7]: http://jinja.pocoo.org/docs/2.10/ +[8]: http://www.pelicanthemes.com/ +[9]: https://github.com/nasskach/pelican-blueidea/tree/58fb13112a2707baa7d65075517c40439ab95c0a +[10]: https://disqus.com/ diff --git a/sources/tech/20190107 How to manage your media with Kodi.md b/sources/tech/20190107 How to manage your media with Kodi.md new file mode 100644 index 0000000000..cea446c5b0 --- /dev/null +++ b/sources/tech/20190107 How to manage your media with Kodi.md @@ -0,0 +1,303 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (How to manage your media with Kodi) +[#]: via: (https://opensource.com/article/19/1/manage-your-media-kodi) +[#]: author: (Steve Ovens https://opensource.com/users/stratusss) + +How to manage your media with Kodi +====== + +![](Get control over your home media content with Kodi media player software.) + +If you, like me, like to own your own data, chances are you also like to purchase movies and TV shows on Blu-Ray or DVD discs. And you may also like to make [ISOs][1] of the videos to keep exact digital copies, as I do. + +For a little while, it might be manageable to have a bunch of files stored in some sort of directory structure. However, as your collection grows, you may want features like resuming from a specific spot; keeping track of where you left off watching a video (i.e., its watched status); storing episode or movie summaries and movie trailers; buying media in multiple languages; or just having a sane way to play all those ISOs you ripped. + +This is where Kodi comes in. + +### What is Kodi? + +Modern [Kodi][2] is the successor to Xbox Media Player, which was discontinued way back in 2003. In June 2004, Xbox Media Center (XBMC) was born. For over three years, XBMC remained on the Xbox. Then in 2007, work began in earnest to port the media player over to Linux. + +![](https://opensource.com/sites/default/files/uploads/00_xbmc_500x300.png) + +Aside from some uninteresting technical history, things remained fairly stable, and XBMC grew in prominence. By 2014, XBMC had a thriving community, and its core functionality grew to include playing games, streaming content from the web, and connecting to mobile devices. This, combined with legal issues involving Xbox in the name, lead the team behind XBMC to rename it Kodi. Kodi is now branded as an "entertainment hub that brings all your digital media together into a beautiful and user-friendly package." + +Today, Kodi has an extensible interface that has allowed the open source community to build new functionality using plugins. Note that, as with all open source software, Kodi's developers are not responsible for the ecosystem's plugins. + +### How do I start? + +For Ubuntu-based distributions, Kodi is just a few short commands away: + +``` +sudo apt install software-properties-common +sudo add-apt-repository ppa:team-xbmc/ppa +sudo apt update +sudo apt install kodi +``` + +In Arch Linux, you can install the latest version from the community repo: + +``` +sudo pacman -S kodi +``` + +Packages were maintained for Fedora 26 by RPM Fusion (referenced in the [Kodi documentation][3]). I tried it on Fedora 29, and it was quite unstable. I'm sure that this will improve over time, but my experience is that Fedora 29 is not the ideal platform for Kodi. + +### OK, it's installed… now what? + +Before we proceed, note that I am making two assumptions about your media content: + + 1. You have your own local, legally attained content. + 2. You have already transferred this content from your DVDs, Blu-Rays, or another digital distribution source to your local directory or network. + + + +Kodi uses a scraping service to pull down TV and movie metadata. For Kodi to match things appropriately, I recommend adopting a directory and file-naming structure similar to this: + +``` +Utopia +├── Utopia.S01.dvd_rip.x264 +│   ├── Utopia.S01E01.dvd_rip.x264.mkv +│   ├── Utopia.S01E02.dvd_rip.x264.mkv +│   ├── Utopia.S01E03.dvd_rip.x264.mkv +│   ├── Utopia.S01E04.dvd_rip.x264.mkv +│   ├── Utopia.S01E05.dvd_rip.x264.mkv +│   ├── Utopia.S01E06.dvd_rip.x264.mkv +└── Utopia.S02.dvd_rip.x264 +    ├── Utopia.S02E01.dvd_rip.x264.mkv +    ├── Utopia.S02E02.dvd_rip.x264.mkv +    ├── Utopia.S02E03.dvd_rip.x264.mkv +    ├── Utopia.S02E04.dvd_rip.x264.mkv +    ├── Utopia.S02E05.dvd_rip.x264.mkv +    └── Utopia.S02E06.dvd_rip.x264.mkv +``` + +I put the source (my DVD) and the codec (x264) in the title, but these are optional. For a TV series, you can include the episode title in the filename if you like. The important part is **SxxExx** , which stands for Season and Episode. This is how Kodi (and by extension the scrapers) can identify your media. + +Assuming you have organized your media like this, let's do some basic Kodi configuration. + +### Add video sources + +Adding video sources is a simple, six-step process: + + 1. Enter the files section + 2. Select **Files** + 3. Click **Add source** + 4. Browse to your source + 5. Define the video content type + 6. Refresh the metadata + + + +If you're impatient, feel free to navigate these steps on your own. But if you want details, keep reading. + +When you first launch Kodi, you'll see the home screen below. Click **Enter files section**. It doesn't matter whether you do this under Movies (as shown here) or TV shows. + +![](https://opensource.com/sites/default/files/uploads/01_fresh_kodi_main_screen.png) + +Next, select the **Videos** folder, click **Files** , and choose **Add videos**. + +![](https://opensource.com/sites/default/files/uploads/02_videos_folder.png) + +![](https://opensource.com/sites/default/files/uploads/03_add_videos.png) + +Either click on **None** and start typing the path to your files or click **Browse** and use the file navigation. + +![](https://opensource.com/sites/default/files/uploads/04_browse_video_source.png) + +![](https://opensource.com/sites/default/files/uploads/05_add_video_source_name.png) + +As you can see in this screenshot, I added my local **Videos** directory. You can set some default options through **Browse** , such as specifying your home folder and any drives you have mounted—maybe on a network file system (NFS), universal plug and play (UPnP) device, Windows Network ([SMB/CIFS][4]), or [zeroconf][5]. I won't cover most of these, as they are outside the scope of this article, but we will use NFS later for one of Kodi's advanced features. + +After you select your path and click OK, identify the type of content you're working with. + +![](https://opensource.com/sites/default/files/uploads/06_define_video_content.png) + +Next, Kodi prompts you to refresh the metadata for the content in the selected directory. This is how Kodi knows what videos you have and their synopsis, cast information, thumbnails, fan art, etc. Select **Yes** , and you can watch the video-scanning progress in the top right-hand corner. + +![](https://opensource.com/sites/default/files/uploads/07_refresh.png) + +![](https://opensource.com/sites/default/files/uploads/08_active_scan_in_progress.png) + +When the scan completes, you'll see lots of useful information, such as video overviews and season and episode descriptions for TV shows. + +![](https://opensource.com/sites/default/files/uploads/09_screen_after_scan.png) + +![](https://opensource.com/sites/default/files/uploads/10_show_description.png) + +You can use the same process for other types of content, such as music or music videos. + +### Increase functionality with add-ons + +One of the most interesting things about open source projects is that the community often extends them well beyond their initial scope. Kodi has a very robust add-on infrastructure. Most of them are produced by Kodi fans who want to extend its default functionality, and sometimes companies (such as the [Plex][6] content streaming service) release official plugins. Be very careful about adding plugins from untrusted sources. Just because you find an add-on on the internet does not mean it is safe! + +**Be warned:** Add-ons are not supported by Kodi's core team! + +Having said that, there are many useful add-ons that are worth your consideration. In my house, we use Kodi for local playback and Plex when we want to access our content outside the house—with one exception. One of our rooms has a poor WiFi signal. I rip my Blu-Rays to very large MKV files (usually 20–40GB each), and the WiFi (and therefore Kodi) can't handle the files without stuttering. Although you can (and we have) dug into some of the advanced buffering options, even those tweaks have proved insufficient with very large files. Since we already have a Plex server that can transcode content, we solved our problem with a Kodi add-on. + +To show how to install an add-on, I'll use Plex as an example. First, click on **Add-ons** in the side panel and select **Enter add-on browser**. Either use the search function or scroll down until you find Plex. + +![](https://opensource.com/sites/default/files/uploads/11_addons.png) + +Select the Plex add-on and click the **Install** button in the lower right-hand corner. + +![](https://opensource.com/sites/default/files/uploads/13_install_plex_addon.png) + +Once the download completes, you can access Plex on the main Kodi screen under **Add-ons**. + +![](https://opensource.com/sites/default/files/uploads/14_addons_finished_installing.png) + +There are several ways to configure an add-on. Some add-ons, such as NHL TV, are configured via a menu accessed by right-clicking the add-on and selecting Configure. Others, such as Plex, display a configuration walk-through when they launch. If an add-on doesn't seem to be configured when you first launch it, try right-clicking its menu and see if a settings option is available there. + +### Coordinating metadata across Kodi devices + +In our house, we have multiple machines that run Kodi. By default, Kodi tracks metadata, such as a video's watched status and show information, locally. Therefore, content updates on one machine won't appear on any other machine—unless you configure all your Kodi devices to store metadata inside an SQL database (which is a feature Kodi supports). This technique is not particularly difficult, but it is more advanced. If you're willing to put in the effort, here's how to do it. + +#### Before you begin + +There are a few things you need to know before configuring shared status for Kodi. + + 1. All content must be on a network share ([Samba][7], NFS, etc.). + 2. All content must be mounted via the network protocol, even if the disks are local to the machine. That means that no matter where the content is physically located, each client must be configured to use a network fileshare source. + 3. You need to be running an SQL-style database. Kodi's official guide walks through MySQL, but I chose MariaDB. + 4. All clients need to have the database port open (port 3306 in the case of MySQL/MariaDB) or the firewalls disabled. + 5. All clients must be running the same version of Kodi + + + +#### Install and configure the database + +If you're running Ubuntu, you can install MariaDB with the following commands: + +``` +sudo apt update +sudo apt install mariadb-server -y +``` + +I am running MariaDB on an Arch Linux machine. The [Arch Wiki][8] documents the initial setup process well, but I'll summarize it here. + +To install, issue the following command: + +``` +sudo pacman -S mariadb +``` + +Most distributions of MariaDB will have the same setup commands. I recommend that you understand what the commands do, but you can safely take the defaults if you're in a home environment. + +``` +sudo systemctl start mariadb +sudo mysql_install_db --user=mysql --basedir=/usr --datadir=/var/lib/mysql +sudo mysql_secure_installation +``` + +Next, edit the MariaDB config file. This file is different depending on your distribution. On Ubuntu, you want to edit **/etc/mysql/mariadb.conf.d/50-server.cnf**. On Arch, the file is either **/etc/my.cnf** or **/etc/mysql/my.cnf**. Locate the line that says **bind-address = 127.0.0.1** and change it to your desired Ethernet port's IP address or to **bind-address = 0.0.0.0** if you want it to listen on all interfaces. + +Restart the service so the change will take effect: + +``` +sudo systemctl restart mariadb +``` + +#### Configure Kodi and MariaDB/MySQL + +To enable Kodi to write to the database, one of two things needs to happen: You can create the database yourself, or you can let Kodi do it for you. In this case, since the only database on this system is for Kodi, I'll create a user with the rights to create any databases that Kodi requires. Do NOT do this if the machine runs more than one database. + +``` +mysql -u root -p +CREATE USER 'kodi' IDENTIFIED BY 'kodi'; +GRANT ALL ON core.md Dict.md lctt2014.md lctt2016.md lctt2018.md README.md TO 'kodi'; +flush privileges; +\q +``` + +This grants the user all rights—essentially enabling it to act as a root user. For my purposes, this is fine. + +Next, on each Kodi device where you want to share metadata, create the following file: **/home/ /.kodi/userdata/advancedsettings.xml**. This file can contain a lot of very advanced, tweakable settings. My devices have these settings: + +``` + +    +        mysql +        mysql-arch.example.com +        3306 +        kodi +        kodi +    +    +        true +        true +    +    +        +        1 +        322122547 +        20 +    + +``` + +The **< cache>** section—which sets how much of a file Kodi will buffer over the network— is optional in this scenario. See the [Kodi wiki][9] for a full breakdown of this file and its options. + +Once the configuration is complete, it's a good idea to close and reopen Kodi to make sure the settings are applied. + +The final step is configuring all the Kodi clients to use the same network share for all their content. Only one client needs to scrap/refresh the metadata if everything is created successfully. When data is collected, you should see that Kodi creates a new database on your SQL server: + +``` +[kodi@kodi-mysql ~]$ mysql -u root -p +Enter password: +Welcome to the MariaDB monitor.  Commands end with ; or \g. +Your MariaDB connection id is 180 +Server version: 10.1.37-MariaDB MariaDB Server + +Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others. + +Type 'help;' or '\h' for help. Type '\c' to clear the current input statement. + +MariaDB [(none)]> show databases; ++--------------------+ +| Database           | ++--------------------+ +| MyVideos107        | +| information_schema | +| mysql              | +| performance_schema | ++--------------------+ +4 rows in set (0.00 sec) +``` + +### Wrapping up + +This article walked through how to get up and running with the basic functionality of Kodi. You should be able to add content and pull down metadata to make browsing your media more convenient. + +You also know how to search for, install, and potentially configure add-ons for additional features. Be extra careful when downloading add-ons, as they are provided by the community at large and not the core developers. It's best to use add-ons only from organizations or companies you trust. + +And you know a bit about sharing metadata across multiple devices. You've been introduced to **advancedsettings.xml** ; hopefully it has piqued your interest. Kodi has a lot of dials and knobs to turn, and you can squeeze a lot of performance and functionality out of the platform with enough experimentation. + +Are you interested in doing more tweaking? What are some of your favorite add-ons or settings? Do you want to know how to change the user interface? What are some of your favorite skins? Let me know in the comments! + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/19/1/manage-your-media-kodi + +作者：[Steve Ovens][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/stratusss +[b]: https://github.com/lujun9972 +[1]: https://en.wikipedia.org/wiki/ISO_image +[2]: https://kodi.tv/ +[3]: https://kodi.wiki/view/HOW-TO:Install_Kodi_for_Linux#Fedora +[4]: https://en.wikipedia.org/wiki/Server_Message_Block +[5]: https://en.wikipedia.org/wiki/Zero-configuration_networking +[6]: https://www.plex.tv +[7]: https://www.samba.org/ +[8]: https://wiki.archlinux.org/index.php/MySQL +[9]: https://kodi.wiki/view/Advancedsettings.xml diff --git a/sources/tech/20190107 Testing isn-t everything.md b/sources/tech/20190107 Testing isn-t everything.md new file mode 100644 index 0000000000..b2a2daaaac --- /dev/null +++ b/sources/tech/20190107 Testing isn-t everything.md @@ -0,0 +1,135 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Testing isn't everything) +[#]: via: (https://arp242.net/weblog/testing.html) +[#]: author: (Martin Tournoij https://arp242.net/) + +Testing isn't everything +====== + +This is adopted from a discussion about [Want to write good unit tests in go? Don’t panic… or should you?][1] While this mainly talks about Go a lot of the points also apply to other languages. + +Some of the most difficult code I’ve worked with is code that is “easily testable”. Code that abstracts everything to the point where you have no idea what’s going on, just so that it can add a “unit test” to what would otherwise be a very straightforward function. DHH called this [Test-induced design damage][2]. + +Testing is just one tool to make sure that your program works, out of several. Another very important tool is writing code in such a way that it is easy to understand and reason about (“simplicity”). + +Books that advocate extensive testing – such as Robert C. Martin’s Clean Code – were written, in part, as a response to ever more complex programs, where you read 1,000 lines of code but still had no idea what’s going on. I recently had to port a simple Java “emoji replacer” (😂 ➙ 😂) to Go. To ensure compatibility I looked up the im­ple­men­ta­tion. It was a whole bunch of classes, factories, and whatnot which all just resulted in calling a regexp on a string. 🤷 + +In dynamic languages like Ruby and Python tests are important for a different reason, as something like this will “work” just fine: + +``` +if condition: + print('w00t') +else: + nonexistent_function() +``` + +Except of course if that `else` branch is entered. It’s easy to typo stuff, or mix stuff up. + +In Go, both of these problems are less of a concern. It has a good static type system, and the focus is on simple straightforward code that is easy to comprehend. Even for a number of dynamic languages there are optional typing systems (function annotations in Python, TypeScript for JavaScript). + +Sometimes you can do a straightforward implementation that doesn’t sacrifice anything for testability; great! But sometimes you have to strike a balance. For some code, not adding a unit test is fine. + +Intensive focus on “unit tests” can be incredibly damaging to a code base. Some codebases have a gazillion unit tests, which makes any change excessively time-consuming as you’re fixing up a whole bunch of tests for even trivial changes. Often times a lot of these tests are just duplicates; adding tests to every layer of a simple CRUD HTTP endpoint is a common example. In many apps it’s fine to just rely on a single integration test. + +Stuff like SQL mocks is another great example. It makes code more complex, harder to change, all so we can say we added a “unit test” to `select * from foo where x=?`. The worst part is, it doesn’t even test anything other than verifying you didn’t typo an SQL query. As soon as the test starts doing anything useful, such as verifying that it actually returns the correct rows from the database, the Unit Test purists will start complaining that it’s not a True Unit Test™ and that You’re Doing It Wrong™. +For most queries, the integration tests and/or manual tests are fine, and extensive SQL mocks are entirely superfluous at best, and harmful at worst. + +There are exceptions, of course; if you’ve got a lot of `if cond { q += "more sql" }` then adding SQL mocks to verify the correctness of that logic might be a good idea. Even in those cases a “non-unit unit test” (e.g. one that just accesses the database) is still a viable option. Integration tests are also still an option. A lot of applications don’t have those kind of complex queries anyway. + +One important reason for the focus on unit tests is to ensure test code runs fast. This was a response to massive test harnesses that take a day to run. This, again, is not really a problem in Go. All integration tests I’ve written run in a reasonable amount of time (several seconds at most, usually faster). The test cache introduced in Go 1.10 makes it even less of a concern. + +Last year a coworker refactored our ETag-based caching library. The old code was very straightforward and easy to understand, and while I’m not claiming it was guaranteed bug-free, it did work very well for a long time. + +It should have been written with some tests in place, but it wasn’t (I didn’t write the original version). Note that the code was not completely untested, as we did have integration tests. + +The refactored version is much more complex. Aside from the two weeks lost on refactoring a working piece of code to … another working piece of code (topic for another post), I’m not so convinced it’s actually that much better. I consider myself a reasonably accomplished and experienced programmer, with a reasonable knowledge and experience in Go. I think that in general, based on feedback from peers and performance reviews, I am at least a programmer of “average” skill level, if not more. + +If an average programmer has trouble comprehending what is in essence a handful of simple functions because there are so many layers of abstractions, then something has gone wrong. The refactor traded one tool to verify correctness (simplicity) with another (testing). Simplicity is hardly a guarantee to ensure correctness, but neither are unit tests. Ideally, we should do both. + +Postscript: the refactor introduced a bug and removed a feature that was useful, but is now harder to add, not in the least because the code is much more complex. + +All units working correctly gives exactly zero guarantees that the program is working correctly. A lot of logic errors won’t be caught because the logic consists of several units working together. So you need integration tests, and if the integration tests duplicate half of your unit tests, then why bother with those unit tests? + +Test Driven Development (TDD) is also just one tool. It works well for some problems; not so much for others. In particular, I think that “forced to write code in tiny units” can be terribly harmful in some cases. Some code is just a serial script which says “do this, and then that, and then this”. Splitting that up in a whole bunch of “tiny units” can greatly reduce how easy the code is to understand, and thus harder to verify that it is correct. + +I’ve had to fix some Ruby code where everything was in tiny units – there is a strong culture of TDD in the Ruby community – and even though the units were easy to understand I found it incredibly hard to understand the application logic. If everything is split in “tiny units” then understanding how everything fits together to create an actual program that does something useful will be much harder. + +You see the same friction in the old microkernel vs. monolithic kernel debate, or the more recent microservices vs. monolithic app one. In principle splitting everything up in small parts sounds like a great idea, but in practice it turns out that making all the small parts work together is a very hard problem. A hybrid approach seems to work best for kernels and app design, balancing the ad­van­tages and downsides of both approaches. I think the same applies to code. + +To be clear, I am not against unit tests or TDD and claiming we should all gung-go cowboy code our way through life 🤠. I write unit tests and practice TDD, when it makes sense. My point is that unit tests and TDD are not the solution to every single last problem and should applied indiscriminately. This is why I use words such as “some” and “often” so frequently. + +This brings me to the topic of testing frameworks. I have never understood what problem libraries such as [goblin][3] are solving. How is this: + +``` +Expect(err).To(nil) +Expect(out).To(test.wantOut) +``` + +An improvement over this? + +``` +if err != nil { + t.Fatal(err) +} + +if out != tt.want { + t.Errorf("out: %q\nwant: %q", out, tt.want) +} +``` + +What’s wrong with `if` and `==`? Why do we need to abstract it? Note that with table-driven tests you’re only typing these checks once, so you’re saving just a few lines here. + +[Ginkgo][4] is even worse. It turns a very simple, straightforward, and understandable piece of code and doesn’t just abstract `if`, it also chops up the execution in several different functions (`BeforeEach()` and `DescribeTable()`). + +This is known as Behaviour-driven development (BDD). I am not entirely sure what to think of BDD. I am skeptical, but I’ve never properly used it in a large project so I’m hesitant to just dismiss it. Note that I said “properly”: most projects don’t really use BDD, they just use a library with a BDD syntax and shoehorn their testing code in to that. That’s ad-hoc BDD, or faux-BDD. + +Whatever merits BDD may have, they are not present simply because your testing code vaguely resembles BDD-style syntax. This on its own demonstrates that BDD is perhaps not a great idea for many projects. + +I think there are real problems with these BDD(-ish) test tools, as they obfuscate what you’re actually doing. No matter what, testing remains a matter of getting the output of a function and checking if that matches what you expected. No testing methodology is going to change that fundamental. The more layers you add on top of that, the harder it will be to debug. + +When determining if something is “easy” then my prime concern is not how easy something is to write, but how easy something is to debug when things fail. I will gladly spend a bit more effort writing things if that makes things a lot easier to debug. + +All code – including testing code – can fail in confusing, surprising, and unexpected ways (a “bug”), and then you’re expected to debug that code. The more complex the code, the harder it is to debug. + +You should expect all code – including testing code – to go through several debugging cycles. Note that with debugging cycle I don’t mean “there is a bug in the code you need to fix”, but rather “I need to look at this code to fix the bug”. + +In general, I already find testing code harder to debug than regular code, as the “code surface” tends to be larger. You have the testing code and the actual implementation code to think of. That’s a lot more than just thinking of the implementation code. + +Adding these abstractions means you will now also have to think about that, too! This might be okay if the abstractions would reduce the scope of what you have to think about, which is a common reason to add abstractions in regular code, but it doesn’t. It just adds more things to think about. + +So these are exactly the wrong kind of abstractions: they wrap and obfuscate, rather than separate concerns and reduce the scope. + +If you’re interested in soliciting contributions from other people in open source projects then making your tests understandable is a very important concern (it’s also important in business context, but a bit less so, as you’ve got actual time to train people). + +Seeing PRs with “here’s the code, it works, but I couldn’t figure out the tests, plz halp!” is not uncommon; and I’m fairly sure that at least a few people never even bothered to submit PRs just because they got stuck on the tests. I know I have. + +There is one open source project that I contributed to, and would like to contribute more to, but don’t because it’s just too hard to write and run tests. Every change is “write working code in 15 minutes, spend 45 minutes dealing with tests”. It’s … no fun at all. + +Writing good software is hard. I’ve got some ideas on how to do it, but don’t have a comprehensive view. I’m not sure if anyone really does. I do know that “always add unit tests” and “always practice TDD” isn’t the answer, in spite of them being useful concepts. To give an analogy: most people would agree that a free market is a good idea, but at the same time even most libertarians would agree it’s not the complete solution to every single problem (well, [some do][5], but those ideas are … rather misguided). + +You can mail me at [martin@arp242.net][6] or [create a GitHub issue][7] for feedback, questions, etc. + +-------------------------------------------------------------------------------- + +via: https://arp242.net/weblog/testing.html + +作者：[Martin Tournoij][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://arp242.net/ +[b]: https://github.com/lujun9972 +[1]: https://medium.com/@jens.neuse/want-to-write-good-unit-tests-in-go-dont-panic-or-should-you-ba3eb5bf4f51 +[2]: http://david.heinemeierhansson.com/2014/test-induced-design-damage.html +[3]: https://github.com/franela/goblin +[4]: https://github.com/onsi/ginkgo +[5]: https://en.wikipedia.org/wiki/Murray_Rothbard#Children's_rights_and_parental_obligations +[6]: mailto:martin@arp242.net +[7]: https://github.com/Carpetsmoker/arp242.net/issues/new diff --git a/sources/tech/20190108 Create your own video streaming server with Linux.md b/sources/tech/20190108 Create your own video streaming server with Linux.md new file mode 100644 index 0000000000..24dd44524d --- /dev/null +++ b/sources/tech/20190108 Create your own video streaming server with Linux.md @@ -0,0 +1,301 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Create your own video streaming server with Linux) +[#]: via: (https://opensource.com/article/19/1/basic-live-video-streaming-server) +[#]: author: (Aaron J.Prisk https://opensource.com/users/ricepriskytreat) + +Create your own video streaming server with Linux +====== +Set up a basic live streaming server on a Linux or BSD operating system. +![](https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/shortcut_command_function_editing_key.png?itok=a0sEc5vo) + +Live video streaming is incredibly popular—and it's still growing. Platforms like Amazon's Twitch and Google's YouTube boast millions of users that stream and consume countless hours of live and recorded media. These services are often free to use but require you to have an account and generally hold your content behind advertisements. Some people don't need their videos to be available to the masses or just want more control over their content. Thankfully, with the power of open source software, anyone can set up a live streaming server. + +### Getting started + +In this tutorial, I'll explain how to set up a basic live streaming server with a Linux or BSD operating system. + +This leads to the inevitable question of system requirements. These can vary, as there are a lot of variables involved with live streaming, such as: + + * **Stream quality:** Do you want to stream in high definition or will standard definition fit your needs? + * **Viewership:** How many viewers are you expecting for your videos? + * **Storage:** Do you plan on keeping saved copies of your video stream? + * **Access:** Will your stream be private or open to the world? + + + +There are no set rules when it comes to system requirements, so I recommend you experiment and find what works best for your needs. I installed my server on a virtual machine with 4GB RAM, a 20GB hard drive, and a single Intel i7 processor core. + +This project uses the Real-Time Messaging Protocol (RTMP) to handle audio and video streaming. There are other protocols available, but I chose RTMP because it has broad support. As open standards like WebRTC become more compatible, I would recommend that route. + +It's also very important to know that "live" doesn't always mean instant. A video stream must be encoded, transferred, buffered, and displayed, which often adds delays. The delay can be shortened or lengthened depending on the type of stream you're creating and its attributes. + +### Setting up a Linux server + +You can use many different distributions of Linux, but I prefer Ubuntu, so I downloaded the [Ubuntu Server][1] edition for my operating system. If you prefer your server to have a graphical user interface (GUI), feel free to use [Ubuntu Desktop][2] or one of its many flavors. Then, I fired up the Ubuntu installer on my computer or virtual machine and chose the settings that best matched my environment. Below are the steps I took. + +Note: Because this is a server, you'll probably want to set some static network settings. + +![](https://opensource.com/sites/default/files/uploads/stream-server_profilesetup.png) + +After the installer finishes and your system reboots, you'll be greeted with a lovely new Ubuntu system. As with any newly installed operating system, install any updates that are available: + +``` +sudo apt update +sudo apt upgrade +``` + +This streaming server will use the very powerful and versatile Nginx web server, so you'll need to install it: + +``` +sudo apt install nginx +``` + +Then you'll need to get the RTMP module so Nginx can handle your media stream: + +``` +sudo add-apt-repository universe +sudo apt install libnginx-mod-rtmp +``` + +Adjust your web server's configuration so it can accept and deliver your media stream. + +``` +sudo nano /etc/nginx/nginx.conf +``` + +Scroll to the bottom of the configuration file and add the following code: + +``` +rtmp { +        server { +                listen 1935; +                chunk_size 4096; + +                application live { +                        live on; +                        record off; +                } +        } +} +``` + +![](https://opensource.com/sites/default/files/uploads/stream-server_config.png) + +Save the config. Because I'm a heretic, I use [Nano][3] for editing configuration files. In Nano, you can save your config by pressing **Ctrl+X** , **Y** , and then **Enter.** + +This is a very minimal config that will create a working streaming server. You'll add to this config later, but this is a great starting point. + +However, before you can begin your first stream, you'll need to restart Nginx with its new configuration: + +``` +sudo systemctl restart nginx +``` + +### Setting up a BSD server + +If you're of the "beastie" persuasion, getting a streaming server up and running is also devilishly easy. + +Head on over to the [FreeBSD][4] website and download the latest release. Fire up the FreeBSD installer on your computer or virtual machine and go through the initial steps and choose settings that best match your environment. Since this is a server, you'll likely want to set some static network settings. + +After the installer finishes and your system reboots, you should have a shiny new FreeBSD system. Like any other freshly installed system, you'll likely want to get everything updated (from this step forward, make sure you're logged in as root): + +``` +pkg update +pkg upgrade +``` + +I install [Nano][3] for editing configuration files: + +``` +pkg install nano +``` + +This streaming server will use the very powerful and versatile Nginx web server. You can build Nginx using the excellent ports system that FreeBSD boasts. + +First, update your ports tree: + +``` +portsnap fetch +portsnap extract +``` + +Browse to the Nginx ports directory: + +``` +cd /usr/ports/www/nginx +``` + +And begin building Nginx by running: + +``` +make install +``` + +You'll see a screen asking what modules to include in your Nginx build. For this project, you'll need to add the RTMP module. Scroll down until the RTMP module is selected and press **Space**. Then Press **Enter** to proceed with the rest of the build and installation. + +Once Nginx has finished installing, it's time to configure it for streaming purposes. + +First, add an entry into **/etc/rc.conf** to ensure the Nginx server starts when your system boots: + +``` +nano /etc/rc.conf +``` + +Add this text to the file: + +``` +nginx_enable="YES" +``` + +![](https://opensource.com/sites/default/files/uploads/stream-server_streamingconfig.png) + +Next, create a webroot directory from where Nginx will serve its content. I call mine **stream** : + +``` +cd /usr/local/www/ +mkdir stream +chmod -R 755 stream/ +``` + +Now that you have created your stream directory, configure Nginx by editing its configuration file: + +``` +nano /usr/local/etc/nginx/nginx.conf +``` + +Load your streaming modules at the top of the file: + +``` +load_module /usr/local/libexec/nginx/ngx_stream_module.so; +load_module /usr/local/libexec/nginx/ngx_rtmp_module.so; +``` + +![](https://opensource.com/sites/default/files/uploads/stream-server_modules.png) + +Under the **Server** section, change the webroot location to match the one you created earlier: + +``` +Location / { +root /usr/local/www/stream +} +``` + +![](https://opensource.com/sites/default/files/uploads/stream-server_webroot.png) + +And finally, add your RTMP settings so Nginx will know how to handle your media streams: + +``` +rtmp { +        server { +                listen 1935; +                chunk_size 4096; + +                application live { +                        live on; +                        record off; +                } +        } +} +``` + +Save the config. In Nano, you can do this by pressing **Ctrl+X** , **Y** , and then **Enter.** + +As you can see, this is a very minimal config that will create a working streaming server. Later, you'll add to this config, but this will provide you with a great starting point. + +However, before you can begin your first stream, you'll need to restart Nginx with its new config: + +``` +service nginx restart +``` + +### Set up your streaming software + +#### Broadcasting with OBS + +Now that your server is ready to accept your video streams, it's time to set up your streaming software. This tutorial uses the powerful and open source Open Broadcast Studio (OBS). + +Head over to the [OBS website][5] and find the build for your operating system and install it. Once OBS launches, you should see a first-time-run wizard that will help you configure OBS with the settings that best fit your hardware. + +![](https://opensource.com/sites/default/files/uploads/stream-server_autoconfig.png) + +OBS isn't capturing anything because you haven't supplied it with a source. For this tutorial, you'll just capture your desktop for the stream. Simply click the **+** button under **Source** , choose **Screen Capture** , and select which desktop you want to capture. + +Click OK, and you should see OBS mirroring your desktop. + +Now it's time to send your newly configured video stream to your server. In OBS, click **File** > **Settings**. Click on the **Stream** section, and set **Stream Type** to **Custom Streaming Server**. + +In the URL box, enter the prefix **rtmp://** followed the IP address of your streaming server followed by **/live**. For example, **rtmp://IP-ADDRESS/live**. + +Next, you'll probably want to enter a Stream key—a special identifier required to view your stream. Enter whatever key you want (and can remember) in the **Stream key** box. + +![](https://opensource.com/sites/default/files/uploads/stream-server_streamkey.png) + +Click **Apply** and then **OK**. + +Now that OBS is configured to send your stream to your server, you can start your first stream. Click **Start Streaming**. + +If everything worked, you should see the button change to **Stop Streaming** and some bandwidth metrics will appear at the bottom of OBS. + +![](https://opensource.com/sites/default/files/uploads/stream-server_metrics.png) + +If you receive an error, double-check Stream Settings in OBS for misspellings. If everything looks good, there could be another issue preventing it from working. + +### Viewing your stream + +A live video isn't much good if no one is watching it, so be your first viewer! + +There are a multitude of open source media players that support RTMP, but the most well-known is probably [VLC media player][6]. + +After you install and launch VLC, open your stream by clicking on **Media** > **Open Network Stream**. Enter the path to your stream, adding the Stream Key you set up in OBS, then click **Play**. For example, **rtmp://IP-ADDRESS/live/SECRET-KEY**. + +You should now be viewing your very own live video stream! + +![](https://opensource.com/sites/default/files/uploads/stream-server_livevideo.png) + +### Where to go next? + +This is a very simple setup that will get you off the ground. Here are two other features you likely will want to use. + + * **Limit access:** The next step you might want to take is to limit access to your server, as the default setup allows anyone to stream to and from the server. There are a variety of ways to set this up, such as an operating system firewall, [.htaccess file][7], or even using the [built-in access controls in the STMP module][8]. + + * **Record streams:** This simple Nginx configuration will only stream and won't save your videos, but this is easy to add. In the Nginx config, under the RTMP section, set up the recording options and the location where you want to save your videos. Make sure the path you set exists and Nginx is able to write to it. + + + + +``` +application live { +             live on; +             record all; +             record_path /var/www/html/recordings; +             record_unique on; +} +``` + +The world of live streaming is constantly evolving, and if you're interested in more advanced uses, there are lots of other great resources you can find floating around the internet. Good luck and happy streaming! + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/19/1/basic-live-video-streaming-server + +作者：[Aaron J.Prisk][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/ricepriskytreat +[b]: https://github.com/lujun9972 +[1]: https://www.ubuntu.com/download/server +[2]: https://www.ubuntu.com/download/desktop +[3]: https://www.nano-editor.org/ +[4]: https://www.freebsd.org/ +[5]: https://obsproject.com/ +[6]: https://www.videolan.org/vlc/index.html +[7]: https://httpd.apache.org/docs/current/howto/htaccess.html +[8]: https://github.com/arut/nginx-rtmp-module/wiki/Directives#access diff --git a/sources/tech/20190108 How ASLR protects Linux systems from buffer overflow attacks.md b/sources/tech/20190108 How ASLR protects Linux systems from buffer overflow attacks.md new file mode 100644 index 0000000000..41d4e47acc --- /dev/null +++ b/sources/tech/20190108 How ASLR protects Linux systems from buffer overflow attacks.md @@ -0,0 +1,133 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (How ASLR protects Linux systems from buffer overflow attacks) +[#]: via: (https://www.networkworld.com/article/3331199/linux/what-does-aslr-do-for-linux.html) +[#]: author: (Sandra Henry-Stocker https://www.networkworld.com/author/Sandra-Henry_Stocker/) + +How ASLR protects Linux systems from buffer overflow attacks +====== + +![](https://images.idgesg.net/images/article/2019/01/shuffling-cards-100784640-large.jpg) + +Address Space Layout Randomization (ASLR) is a memory-protection process for operating systems that guards against buffer-overflow attacks. It helps to ensure that the memory addresses associated with running processes on systems are not predictable, thus flaws or vulnerabilities associated with these processes will be more difficult to exploit. + +ASLR is used today on Linux, Windows, and MacOS systems. It was first implemented on Linux in 2005. In 2007, the technique was deployed on Microsoft Windows and MacOS. While ASLR provides the same function on each of these operating systems, it is implemented differently on each one. + +The effectiveness of ASLR is dependent on the entirety of the address space layout remaining unknown to the attacker. In addition, only executables that are compiled as Position Independent Executable (PIE) programs will be able to claim the maximum protection from ASLR technique because all sections of the code will be loaded at random locations. PIE machine code will execute properly regardless of its absolute address. + +**[ Also see:[Invaluable tips and tricks for troubleshooting Linux][1] ]** + +### ASLR limitations + +In spite of ASLR making exploitation of system vulnerabilities more difficult, its role in protecting systems is limited. It's important to understand that ASLR: + + * Doesn't _resolve_ vulnerabilities, but makes exploiting them more of a challenge + * Doesn't track or report vulnerabilities + * Doesn't offer any protection for binaries that are not built with ASLR support + * Isn't immune to circumvention + + + +### How ASLR works + +ASLR increases the control-flow integrity of a system by making it more difficult for an attacker to execute a successful buffer-overflow attack by randomizing the offsets it uses in memory layouts. + +ASLR works considerably better on 64-bit systems, as these systems provide much greater entropy (randomization potential). + +### Is ASLR working on your Linux system? + +Either of the two commands shown below will tell you whether ASLR is enabled on your system. + +``` +$ cat /proc/sys/kernel/randomize_va_space +2 +$ sysctl -a --pattern randomize +kernel.randomize_va_space = 2 +``` + +The value (2) shown in the commands above indicates that ASLR is working in full randomization mode. The value shown will be one of the following: + +``` +0 = Disabled +1 = Conservative Randomization +2 = Full Randomization +``` + +If you disable ASLR and run the commands below, you should notice that the addresses shown in the **ldd** output below are all the same in the successive **ldd** commands. The **ldd** command works by loading the shared objects and showing where they end up in memory. + +``` +$ sudo sysctl -w kernel.randomize_va_space=0 <== disable +[sudo] password for shs: +kernel.randomize_va_space = 0 +$ ldd /bin/bash + linux-vdso.so.1 (0x00007ffff7fd1000) <== same addresses + libtinfo.so.6 => /lib/x86_64-linux-gnu/libtinfo.so.6 (0x00007ffff7c69000) + libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007ffff7c63000) + libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007ffff7a79000) + /lib64/ld-linux-x86-64.so.2 (0x00007ffff7fd3000) +$ ldd /bin/bash + linux-vdso.so.1 (0x00007ffff7fd1000) <== same addresses + libtinfo.so.6 => /lib/x86_64-linux-gnu/libtinfo.so.6 (0x00007ffff7c69000) + libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007ffff7c63000) + libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007ffff7a79000) + /lib64/ld-linux-x86-64.so.2 (0x00007ffff7fd3000) +``` + +If the value is set back to **2** to enable ASLR, you will see that the addresses will change each time you run the command. + +``` +$ sudo sysctl -w kernel.randomize_va_space=2 <== enable +[sudo] password for shs: +kernel.randomize_va_space = 2 +$ ldd /bin/bash + linux-vdso.so.1 (0x00007fff47d0e000) <== first set of addresses + libtinfo.so.6 => /lib/x86_64-linux-gnu/libtinfo.so.6 (0x00007f1cb7ce0000) + libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007f1cb7cda000) + libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f1cb7af0000) + /lib64/ld-linux-x86-64.so.2 (0x00007f1cb8045000) +$ ldd /bin/bash + linux-vdso.so.1 (0x00007ffe1cbd7000) <== second set of addresses + libtinfo.so.6 => /lib/x86_64-linux-gnu/libtinfo.so.6 (0x00007fed59742000) + libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007fed5973c000) + libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007fed59552000) + /lib64/ld-linux-x86-64.so.2 (0x00007fed59aa7000) +``` + +### Attempting to bypass ASLR + +In spite of its advantages, attempts to bypass ASLR are not uncommon and seem to fall into several categories: + + * Using address leaks + * Gaining access to data relative to particular addresses + * Exploiting implementation weaknesses that allow attackers to guess addresses when entropy is low or when the ASLR implementation is faulty + * Using side channels of hardware operation + + + +### Wrap-up + +ASLR is of great value, especially when run on 64 bit systems and implemented properly. While not immune from circumvention attempts, it does make exploitation of system vulnerabilities considerably more difficult. Here is a reference that can provide a lot more detail [on the Effectiveness of Full-ASLR on 64-bit Linux][2], and here is a paper on one circumvention effort to [bypass ASLR][3] using branch predictors. + +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/3331199/linux/what-does-aslr-do-for-linux.html + +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://www.networkworld.com/article/3242170/linux/invaluable-tips-and-tricks-for-troubleshooting-linux.html +[2]: https://cybersecurity.upv.es/attacks/offset2lib/offset2lib-paper.pdf +[3]: http://www.cs.ucr.edu/~nael/pubs/micro16.pdf +[4]: https://www.facebook.com/NetworkWorld/ +[5]: https://www.linkedin.com/company/network-world diff --git a/sources/tech/20190108 How To Understand And Identify File types in Linux.md b/sources/tech/20190108 How To Understand And Identify File types in Linux.md new file mode 100644 index 0000000000..c1c4ca4c0a --- /dev/null +++ b/sources/tech/20190108 How To Understand And Identify File types in Linux.md @@ -0,0 +1,359 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: 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：[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 diff --git a/sources/tech/20190109 Automating deployment strategies with Ansible.md b/sources/tech/20190109 Automating deployment strategies with Ansible.md new file mode 100644 index 0000000000..175244e760 --- /dev/null +++ b/sources/tech/20190109 Automating deployment strategies with Ansible.md @@ -0,0 +1,152 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Automating deployment strategies with Ansible) +[#]: via: (https://opensource.com/article/19/1/automating-deployment-strategies-ansible) +[#]: author: (Jario da Silva Junior https://opensource.com/users/jairojunior) + +Automating deployment strategies with Ansible +====== +Use automation to eliminate time sinkholes due to repetitive tasks and unplanned work. +![](https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/innovation_lightbulb_gears_devops_ansible.png?itok=TSbmp3_M) + +When you examine your technology stack from the bottom layer to the top—hardware, operating system (OS), middleware, and application—with their respective configurations, it's clear that changes are far more frequent as you go up in the stack. Your hardware will hardly change, your OS has a long lifecycle, and your middleware will keep up with the application's needs, but even if your release cycle is long (weeks or months), your applications will be the most volatile. + +![](https://opensource.com/sites/default/files/uploads/osdc-deployment-strategies.png) + +In [The Practice of System and Network Administration][1], the authors categorize the biggest "time sinkholes" in IT as manual/non-standard provisioning of OSes and application deployments. These time sinkholes will consume you with repetitive tasks or unplanned work. + +How so? Let's say you provision a new server without Network Time Protocol (NTP) properly configured, and a small percentage of your requests—in a cluster of dozens of servers—start to behave strangely because an application uses some sort of scheduler that relies on correct time. When you look at it like this, it is an easy problem to fix, but how long it would it take your team figure it out? Incidents or unplanned work consume a lot of your time and, even worse, your greatest talents. Should you really be wasting time investigating production systems like this? Wouldn't it be better to set this server aside and automatically provision a new one from scratch? + +What about manual deployment? Imagine 20 binaries deployed across a farm or nodes with their respective configuration files? How error-prone is this? Inevitably, it will eventually end up in unplanned work. + +The [State of DevOps Report 2018][2] introduces the stages of DevOps adoption, and it's no surprise that Stage 0 includes deployment automation and reuse of deployment patterns, while Stage 1 and 2 focus on standardization of your infrastructure stack to reduce inconsistencies across your environment. + +Note that, more than once, I have seen an ops team using this "standardization" as an excuse to limit a development team's ability to deliver, forcing them to use a hammer on something that is definitely not a nail. Don't do it; the price is extremely high. + +The lesson to be learned here is that lack of automation not only increases your lead time but also the rate of problems in your process and the amount of unplanned work you face. If you've read [The Phoenix Project][3], you know this is the root of all evil in any value stream, and if you don't get rid of it, it will eventually kill your business. + +When trying to fill the biggest time sinkholes, why not start with automating operating system installation? We could, but the results would take longer to appear since new virtual machines are not created as frequently as applications are deployed. In other words, this may not free up the time we need to power our initiative, so it could die prematurely. + +Still not convinced? Smaller and more frequent releases are also extremely positive from the development side. Let's explain a little further… + +### Deploy ≠ Release + +The first thing to understand is that, although they're used interchangeably, deployment and release do **NOT** mean the same thing. Release refers to providing the user a new version, while deployment is the technical process of deploying the new version. Let's focus on the technical process of deployment. + +### Tasks, groups, and Ansible + +We need to understand the deployment process from the beginning to the end, including everything in the middle—the tasks, which servers are involved in the process, and which steps are executed—to avoid falling into the pitfalls described by Mattias Geniar in [Automating the unknown][4]. + +#### Tasks + +The steps commonly executed in a regular deployment process include: + + * Deploy application(s)/database(s) or database(s) change(s) + * Stop/start services and monitoring + * Add/remove the server from our load balancers + * Verify application state—is it ready to serve requests? + * Manual approval—is it necessary? + + + +For some people, automating the deployment process but leaving a manual approval step is like riding a bike with training wheels. As someone once told me: "It's better to ride with training wheels than not ride at all." + +What if a tool doesn't include an API or a command-line interface (CLI) to enable task automation? Well, maybe it's time to think about changing tools. There are many open source application servers, databases, monitoring systems, and load balancers that are easily automated—thanks in large part to the [Unix way][5]. When adopting a new technology, eliminate options that are not automated and use your creativity to support your legacy technologies. For example, I've seen people versioning network appliance configuration files and updating them using FTP. + +And guess what? It's a wonderful time to adopt open source tools. The recent [Accelerate: State of DevOps][6] report found that open source technologies are in predominant use in high-performance organizations. The logic is pretty simple: open source projects function in a "Darwinist" model, where those that do not adapt and evolve will die for lack of a user base or contributions. Feedback is paramount to software evolution. + +#### Groups + +To identify groups of servers to target for automation, think about the most tasks you want to automate, such as those that: + + * Deploy application(s)/database(s) or database change(s) + * Stop/start services and monitoring + * Add/remove server(s) from load balancer(s) + * Verify application state—is it ready to serve requests? + + + +#### The playbook + +A high-level deployment process could be: + + 1. Stop monitoring (to avoid false-positives) + 2. Remove server from the load balancer (to prevent the user from receiving an error code) + 3. Stop the service (to enable a graceful shutdown) + 4. Deploy the new version of the application + 5. Wait for the application to be ready to receive new requests + 6. Execute steps 3, 2, and 1. + 7. Do the same for the next N servers. + + + +Having documentation of your process is nice, but having an executable documenting your deployment is better! Here's what steps 1–5 would look like in Ansible for a fully open source stack: + +``` +- name: Disable alerts +  nagios: +    action: disable_alerts +    host: "{{ inventory_hostname }}" +    services: webserver +  delegate_to: "{{ item }}" +  loop: "{{ groups.monitoring }}" + +- name: Disable servers in the LB +  haproxy: +    host: "{{ inventory_hostname }}" +    state: disabled +    backend: app +  delegate_to: "{{ item }}" +  loop: " {{ groups.lbserver }}" + +- name: Stop the service +  service: name=httpd state=stopped + +- name: Deploy a new version +  unarchive: src=app.tar.gz dest=/var/www/app + +- name: Verify application state +  uri: +    url: "http://{{ inventory_hostname }}/app/healthz" +    status_code: 200 +  retries: 5 +``` + +### Why Ansible? + +There are other alternatives for application deployment, but the things that make Ansible an excellent choice include: + + * Multi-tier orchestration (i.e., **delegate_to** ) allowing you to orderly target different groups of servers: monitoring, load balancer, application server, database, etc. + * Rolling upgrade (i.e., serial) to control how changes are made (e.g., 1 by 1, N by N, X% at a time, etc.) + * Error control, **max_fail_percentage** and **any_errors_fatal** , is my process all-in or will it tolerate fails? + * A vast library of modules for: + * Monitoring (e.g., Nagios, Zabbix, etc.) + * Load balancers (e.g., HAProxy, F5, Netscaler, Cisco, etc.) + * Services (e.g., service, command, file) + * Deployment (e.g., copy, unarchive) + * Programmatic verifications (e.g., command, Uniform Resource Identifier) + + + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/19/1/automating-deployment-strategies-ansible + +作者：[Jario da Silva Junior][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/jairojunior +[b]: https://github.com/lujun9972 +[1]: https://www.amazon.com/Practice-System-Network-Administration-Enterprise/dp/0321919165/ref=dp_ob_title_bk +[2]: https://puppet.com/resources/whitepaper/state-of-devops-report +[3]: https://www.amazon.com/Phoenix-Project-DevOps-Helping-Business/dp/0988262592 +[4]: https://ma.ttias.be/automating-unknown/ +[5]: https://en.wikipedia.org/wiki/Unix_philosophy +[6]: https://cloudplatformonline.com/2018-state-of-devops.html diff --git a/sources/tech/20190109 Bash 5.0 Released with New Features.md b/sources/tech/20190109 Bash 5.0 Released with New Features.md new file mode 100644 index 0000000000..46d9aeae59 --- /dev/null +++ b/sources/tech/20190109 Bash 5.0 Released with New Features.md @@ -0,0 +1,80 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Bash 5.0 Released with New Features) +[#]: via: (https://itsfoss.com/bash-5-release) +[#]: author: (Ankush Das https://itsfoss.com/author/ankush/) + +Bash 5.0 Released with New Features +====== + +The [mailing list][1] confirmed the release of Bash-5.0 recently. And, it is exciting to know that it comes baked with new features and variable. + +Well, if you’ve been using Bash 4.4.XX, you will definitely love the fifth major release of [Bash][2]. + +The fifth release focuses on new shell variables and a lot of major bug fixes with an overhaul. It also introduces a couple of new features along with some incompatible changes between bash-4.4 and bash-5.0. + +![Bash logo][3] + +### What about the new features? + +The mailing list explains the bug fixed in this new release: + +> This release fixes several outstanding bugs in bash-4.4 and introduces several new features. The most significant bug fixes are an overhaul of how nameref variables resolve and a number of potential out-of-bounds memory errors discovered via fuzzing. There are a number of changes to the expansion of $@ and $* in various contexts where word splitting is not performed to conform to a Posix standard interpretation, and additional changes to resolve corner cases for Posix conformance. + +It also introduces some new features. As per the release note, these are the most notable new features are several new shell variables: + +> The BASH_ARGV0, EPOCHSECONDS, and EPOCHREALTIME. The ‘history’ builtin can remove ranges of history entries and understands negative arguments as offsets from the end of the history list. There is an option to allow local variables to inherit the value of a variable with the same name at a preceding scope. There is a new shell option that, when enabled, causes the shell to attempt to expand associative array subscripts only once (this is an issue when they are used in arithmetic expressions). The ‘globasciiranges‘ shell option is now enabled by default; it can be set to off by default at configuration time. + +### What about the changes between Bash-4.4 and Bash-5.0? + +The update log mentioned about the incompatible changes and the supported readline version history. Here’s what it said: + +> There are a few incompatible changes between bash-4.4 and bash-5.0. The changes to how nameref variables are resolved means that some uses of namerefs will behave differently, though I have tried to minimize the compatibility issues. By default, the shell only sets BASH_ARGC and BASH_ARGV at startup if extended debugging mode is enabled; it was an oversight that it was set unconditionally and caused performance issues when scripts were passed large numbers of arguments. +> +> Bash can be linked against an already-installed Readline library rather than the private version in lib/readline if desired. Only readline-8.0 and later versions are able to provide all of the symbols that bash-5.0 requires; earlier versions of the Readline library will not work correctly. + +I believe some of the features/variables added are very useful. Some of my favorites are: + + * There is a new (disabled by default, undocumented) shell option to enable and disable sending history to syslog at runtime. + * The shell doesn’t automatically set BASH_ARGC and BASH_ARGV at startup unless it’s in debugging mode, as the documentation has always said, but will dynamically create them if a script references them at the top level without having enabled debugging mode. + * The ‘history’ can now delete ranges of history entries using ‘-d start-end’. + * If a non-interactive shell with job control enabled detects that a foreground job died due to SIGINT, it acts as if it received the SIGINT. + * BASH_ARGV0: a new variable that expands to $0 and sets $0 on assignment. + + + +To check the complete list of changes and features you should refer to the [Mailing list post][1]. + +### Wrapping Up + +You can check your current Bash version, using this command: + +``` +bash --version +``` + +It’s more likely that you’ll have Bash 4.4 installed. If you want to get the new version, I would advise waiting for your distribution to provide it. + +With Bash-5.0 available, what do you think about it? Are you using any alternative to bash? If so, would this update change your mind? + +Let us know your thoughts in the comments below. + +-------------------------------------------------------------------------------- + +via: https://itsfoss.com/bash-5-release + +作者：[Ankush Das][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://itsfoss.com/author/ankush/ +[b]: https://github.com/lujun9972 +[1]: https://lists.gnu.org/archive/html/bug-bash/2019-01/msg00063.html +[2]: https://www.gnu.org/software/bash/ +[3]: https://i1.wp.com/itsfoss.com/wp-content/uploads/2019/01/bash-logo.jpg?resize=800%2C450&ssl=1 diff --git a/sources/tech/20190109 Understanding -etc-services file in Linux.md b/sources/tech/20190109 Understanding -etc-services file in Linux.md new file mode 100644 index 0000000000..1b1028ca6d --- /dev/null +++ b/sources/tech/20190109 Understanding -etc-services file in Linux.md @@ -0,0 +1,76 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Understanding /etc/services file in Linux) +[#]: via: (https://kerneltalks.com/linux/understanding-etc-services-file-in-linux/) +[#]: author: (kerneltalks https://kerneltalks.com) + +Understanding /etc/services file in Linux +====== + +Article which helps you to understand /etc/services file in Linux. Learn about content, format & importance of this file. + +![/etc/services file in Linux][1] +/etc/services file in Linux + +Internet daemon is important service in Linux world. It takes care of all network services with the help of `/etc/services` file. In this article we will walk you through content, format of this file and what it means to a Linux system. + +`/etc/services` file contains list of network services and ports mapped to them. `inetd` or `xinetd` looks at these details so that it can call particular program when packet hits respective port and demand for service. + +As a normal user you can view this file since file is world readable. To edit this file you need to have root privileges. + +``` +$ ll /etc/services +-rw-r--r--. 1 root root 670293 Jun 7 2013 /etc/services +``` + +### `/etc/services` file format + +``` +service-name port/protocol [aliases..] [#comment] +``` + +Last two fields are optional hence denoted in `[` `]` + +where – + + * service-name is name of the network service. e.g. [telnet][2], [ftp][3] etc. + * port/protocol is port being used by that network service (numerical value) and protocol (TCP/UDP) used for communication by service. + * alias is alternate name for service. + * comment is note or description you can add to service. Starts with `#` mark + + + +### Sample` /etc/services` file + +``` +# Each line describes one service, and is of the form: +# +# service-name port/protocol [aliases ...] [# comment] + +tcpmux 1/tcp # TCP port service multiplexer +rje 5/tcp # Remote Job Entry +echo 7/udp +discard 9/udp sink null +``` + +Here, you can see use of optional last two fields as well. `discard` service has alternate name as `sink` or `null`. + +-------------------------------------------------------------------------------- + +via: https://kerneltalks.com/linux/understanding-etc-services-file-in-linux/ + +作者：[kerneltalks][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://kerneltalks.com +[b]: https://github.com/lujun9972 +[1]: https://i2.wp.com/kerneltalks.com/wp-content/uploads/2019/01/undestanding-etc-service-file-in-linux.png?ssl=1 +[2]: https://kerneltalks.com/config/configure-telnet-server-linux/ +[3]: https://kerneltalks.com/config/ftp-server-configuration-steps-rhel-6/ diff --git a/sources/tech/20190110 5 useful Vim plugins for developers.md b/sources/tech/20190110 5 useful Vim plugins for developers.md new file mode 100644 index 0000000000..2b5b9421d4 --- /dev/null +++ b/sources/tech/20190110 5 useful Vim plugins for developers.md @@ -0,0 +1,369 @@ +[#]: collector: (lujun9972) +[#]: translator: (pityonline) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (5 useful Vim plugins for developers) +[#]: via: (https://opensource.com/article/19/1/vim-plugins-developers) +[#]: author: (Ricardo Gerardi https://opensource.com/users/rgerardi) + +5 useful Vim plugins for developers +====== +Expand Vim's capabilities and improve your workflow with these five plugins for writing code. +![](https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/web_browser_desktop_devlopment_design_system_computer.jpg?itok=pfqRrJgh) + +I have used [Vim][1] as a text editor for over 20 years, but about two years ago I decided to make it my primary text editor. I use Vim to write code, configuration files, blog articles, and pretty much everything I can do in plaintext. Vim has many great features and, once you get used to it, you become very productive. + +I tend to use Vim's robust native capabilities for most of what I do, but there are a number of plugins developed by the open source community that extend Vim's capabilities, improve your workflow, and make you even more productive. + +Following are five plugins that are useful when using Vim to write code in any programming language. + +### 1. Auto Pairs + +The [Auto Pairs][2] plugin helps insert and delete pairs of characters, such as brackets, parentheses, or quotation marks. This is very useful for writing code, since most programming languages use pairs of characters in their syntax—such as parentheses for function calls or quotation marks for string definitions. + +In its most basic functionality, Auto Pairs inserts the corresponding closing character when you type an opening character. For example, if you enter a bracket **[** , Auto-Pairs automatically inserts the closing bracket **]**. Conversely, if you use the Backspace key to delete the opening bracket, Auto Pairs deletes the corresponding closing bracket. + +If you have automatic indentation on, Auto Pairs inserts the paired character in the proper indented position when you press Return/Enter, saving you from finding the correct position and typing the required spaces or tabs. + +Consider this Go code block for instance: + +``` +package main + +import "fmt" + +func main() { +    x := true +    items := []string{"tv", "pc", "tablet"} + +    if x { +        for _, i := range items +    } +} +``` + +Inserting an opening curly brace **{** after **items** and pressing Return/Enter produces this result: + +``` +package main + +import "fmt" + +func main() { +    x := true +    items := []string{"tv", "pc", "tablet"} + +    if x { +        for _, i := range items  { +            | (cursor here) +        } +    } +} +``` + +Auto Pairs offers many other options (which you can read about on [GitHub][3]), but even these basic features will save time. + +### 2. NERD Commenter + +The [NERD Commenter][4] plugin adds code-commenting functions to Vim, similar to the ones found in an integrated development environment (IDE). With this plugin installed, you can select one or several lines of code and change them to comments with the press of a button. + +NERD Commenter integrates with the standard Vim [filetype][5] plugin, so it understands several programming languages and uses the appropriate commenting characters for single or multi-line comments. + +The easiest way to get started is by pressing **Leader+Space** to toggle the current line between commented and uncommented. The standard Vim Leader key is the **\** character. + +In Visual mode, you can select multiple lines and toggle their status at the same time. NERD Commenter also understands counts, so you can provide a count n followed by the command to change n lines together. + +Other useful features are the "Sexy Comment," triggered by **Leader+cs** , which creates a fancy comment block using the multi-line comment character. For example, consider this block of code: + +``` +package main + +import "fmt" + +func main() { +    x := true +    items := []string{"tv", "pc", "tablet"} + +    if x { +        for _, i := range items { +            fmt.Println(i) +        } +    } +} +``` + +Selecting all the lines in **function main** and pressing **Leader+cs** results in the following comment block: + +``` +package main + +import "fmt" + +func main() { +/* + *    x := true + *    items := []string{"tv", "pc", "tablet"} + * + *    if x { + *        for _, i := range items { + *            fmt.Println(i) + *        } + *    } + */ +} +``` + +Since all the lines are commented in one block, you can uncomment the entire block by toggling any of the lines of the block with **Leader+Space**. + +NERD Commenter is a must-have for any developer using Vim to write code. + +### 3. VIM Surround + +The [Vim Surround][6] plugin helps you "surround" existing text with pairs of characters (such as parentheses or quotation marks) or tags (such as HTML or XML tags). It's similar to Auto Pairs but, instead of working while you're inserting text, it's more useful when you're editing text. + +For example, if you have the following sentence: + +``` +"Vim plugins are awesome !" +``` + +You can remove the quotation marks around the sentence by pressing the combination **ds"** while your cursor is anywhere between the quotation marks: + +``` +Vim plugins are awesome ! +``` + +You can also change the double quotation marks to single quotation marks with the command **cs"'** : + +``` +'Vim plugins are awesome !' +``` + +Or replace them with brackets by pressing **cs'[** + +``` +[ Vim plugins are awesome ! ] +``` + +While it's a great help for text objects, this plugin really shines when working with HTML or XML tags. Consider the following HTML line: + +``` +

Vim plugins are awesome !

+``` + +You can emphasize the word "awesome" by pressing the combination **ysiw ** while the cursor is anywhere on that word: + +``` +

Vim plugins are awesome !

+``` + +Notice that the plugin is smart enough to use the proper closing tag **< /em>**. + +Vim Surround can also indent text and add tags in their own lines using **ySS**. For example, if you have: + +``` +

Vim plugins are awesome !

+``` + +Add a **div** tag with this combination: **ySS
**, and notice that the paragraph line is indented automatically. + +``` +
+       

Vim plugins are awesome !

+
+``` + +Vim Surround has many other options. Give it a try—and consult [GitHub][7] for additional information. + +### 4\. Vim Gitgutter + +The [Vim Gitgutter][8] plugin is useful for anyone using Git for version control. It shows the output of **Git diff** as symbols in the "gutter"—the sign column where Vim presents additional information, such as line numbers. For example, consider the following as the committed version in Git: + +``` +  1 package main +  2 +  3 import "fmt" +  4 +  5 func main() { +  6     x := true +  7     items := []string{"tv", "pc", "tablet"} +  8 +  9     if x { + 10         for _, i := range items { + 11             fmt.Println(i) + 12         } + 13     } + 14 } +``` + +After making some changes, Vim Gitgutter displays the following symbols in the gutter: + +``` +    1 package main +    2 +    3 import "fmt" +    4 +_   5 func main() { +    6     items := []string{"tv", "pc", "tablet"} +    7 +~   8     if len(items) > 0 { +    9         for _, i := range items { +   10             fmt.Println(i) ++  11             fmt.Println("------") +   12         } +   13     } +   14 } +``` + +The **-** symbol shows that a line was deleted between lines 5 and 6. The **~** symbol shows that line 8 was modified, and the symbol **+** shows that line 11 was added. + +In addition, Vim Gitgutter allows you to navigate between "hunks"—individual changes made in the file—with **[c** and **]c** , or even stage individual hunks for commit by pressing **Leader+hs**. + +This plugin gives you immediate visual feedback of changes, and it's a great addition to your toolbox if you use Git. + +### 5\. VIM Fugitive + +[Vim Fugitive][9] is another great plugin for anyone incorporating Git into the Vim workflow. It's a Git wrapper that allows you to execute Git commands directly from Vim and integrates with Vim's interface. This plugin has many features—check its [GitHub][10] page for more information. + +Here's a basic Git workflow example using Vim Fugitive. Considering the changes we've made to the Go code block on section 4, you can use **git blame** by typing the command **:Gblame** : + +``` +e9949066 (Ricardo Gerardi   2018-12-05 18:17:19 -0500)│    1 package main +e9949066 (Ricardo Gerardi   2018-12-05 18:17:19 -0500)│    2 +e9949066 (Ricardo Gerardi   2018-12-05 18:17:19 -0500)│    3 import "fmt" +e9949066 (Ricardo Gerardi   2018-12-05 18:17:19 -0500)│    4 +e9949066 (Ricardo Gerardi   2018-12-05 18:17:19 -0500)│_   5 func main() { +e9949066 (Ricardo Gerardi   2018-12-05 18:17:19 -0500)│    6     items := []string{"tv", "pc", "tablet"} +e9949066 (Ricardo Gerardi   2018-12-05 18:17:19 -0500)│    7 +00000000 (Not Committed Yet 2018-12-05 18:55:00 -0500)│~   8     if len(items) > 0 { +e9949066 (Ricardo Gerardi   2018-12-05 18:17:19 -0500)│    9         for _, i := range items { +e9949066 (Ricardo Gerardi   2018-12-05 18:17:19 -0500)│   10             fmt.Println(i) +00000000 (Not Committed Yet 2018-12-05 18:55:00 -0500)│+  11             fmt.Println("------") +e9949066 (Ricardo Gerardi   2018-12-05 18:17:19 -0500)│   12         } +e9949066 (Ricardo Gerardi   2018-12-05 18:17:19 -0500)│   13     } +e9949066 (Ricardo Gerardi   2018-12-05 18:17:19 -0500)│   14 } +``` + +You can see that lines 8 and 11 have not been committed. Check the repository status by typing **:Gstatus** : + +``` + 1 # On branch master +  2 # Your branch is up to date with 'origin/master'. +  3 # +  4 # Changes not staged for commit: +  5 #   (use "git add ..." to update what will be committed) +  6 #   (use "git checkout -- ..." to discard changes in working directory) +  7 # +  8 #       modified:   vim-5plugins/examples/test1.go +  9 # + 10 no changes added to commit (use "git add" and/or "git commit -a") +-------------------------------------------------------------------------------------------------------- +    1 package main +    2 +    3 import "fmt" +    4 +_   5 func main() { +    6     items := []string{"tv", "pc", "tablet"} +    7 +~   8     if len(items) > 0 { +    9         for _, i := range items { +   10             fmt.Println(i) ++  11             fmt.Println("------") +   12         } +   13     } +   14 } +``` + +Vim Fugitive opens a split window with the result of **git status**. You can stage a file for commit by pressing the **-** key on the line with the name of the file. You can reset the status by pressing **-** again. The message updates to reflect the new status: + +``` +  1 # On branch master +  2 # Your branch is up to date with 'origin/master'. +  3 # +  4 # Changes to be committed: +  5 #   (use "git reset HEAD ..." to unstage) +  6 # +  7 #       modified:   vim-5plugins/examples/test1.go +  8 # +-------------------------------------------------------------------------------------------------------- +    1 package main +    2 +    3 import "fmt" +    4 +_   5 func main() { +    6     items := []string{"tv", "pc", "tablet"} +    7 +~   8     if len(items) > 0 { +    9         for _, i := range items { +   10             fmt.Println(i) ++  11             fmt.Println("------") +   12         } +   13     } +   14 } +``` + +Now you can use the command **:Gcommit** to commit the changes. Vim Fugitive opens another split that allows you to enter a commit message: + +``` +  1 vim-5plugins: Updated test1.go example file +  2 # Please enter the commit message for your changes. Lines starting +  3 # with '#' will be ignored, and an empty message aborts the commit. +  4 # +  5 # On branch master +  6 # Your branch is up to date with 'origin/master'. +  7 # +  8 # Changes to be committed: +  9 #       modified:   vim-5plugins/examples/test1.go + 10 # +``` + +Save the file with **:wq** to complete the commit: + +``` +[master c3bf80f] vim-5plugins: Updated test1.go example file + 1 file changed, 2 insertions(+), 2 deletions(-) +Press ENTER or type command to continue +``` + +You can use **:Gstatus** again to see the result and **:Gpush** to update the remote repository with the new commit. + +``` +  1 # On branch master +  2 # Your branch is ahead of 'origin/master' by 1 commit. +  3 #   (use "git push" to publish your local commits) +  4 # +  5 nothing to commit, working tree clean +``` + +If you like Vim Fugitive and want to learn more, the GitHub repository has links to screencasts showing additional functionality and workflows. Check it out! + +### What's next? + +These Vim plugins help developers write code in any programming language. There are two other categories of plugins to help developers: code-completion plugins and syntax-checker plugins. They are usually related to specific programming languages, so I will cover them in a follow-up article. + +Do you have another Vim plugin you use when writing code? Please share it in the comments below. + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/19/1/vim-plugins-developers + +作者：[Ricardo Gerardi][a] +选题：[lujun9972][b] +译者：[pityonline](https://github.com/pityonline) +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/rgerardi +[b]: https://github.com/lujun9972 +[1]: https://www.vim.org/ +[2]: https://www.vim.org/scripts/script.php?script_id=3599 +[3]: https://github.com/jiangmiao/auto-pairs +[4]: https://github.com/scrooloose/nerdcommenter +[5]: http://vim.wikia.com/wiki/Filetype.vim +[6]: https://www.vim.org/scripts/script.php?script_id=1697 +[7]: https://github.com/tpope/vim-surround +[8]: https://github.com/airblade/vim-gitgutter +[9]: https://www.vim.org/scripts/script.php?script_id=2975 +[10]: https://github.com/tpope/vim-fugitive diff --git a/sources/tech/20190111 Build a retro gaming console with RetroPie.md b/sources/tech/20190111 Build a retro gaming console with RetroPie.md new file mode 100644 index 0000000000..eedac575c9 --- /dev/null +++ b/sources/tech/20190111 Build a retro gaming console with RetroPie.md @@ -0,0 +1,82 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Build a retro gaming console with RetroPie) +[#]: via: (https://opensource.com/article/19/1/retropie) +[#]: author: (Jay LaCroix https://opensource.com/users/jlacroix) + +Build a retro gaming console with RetroPie +====== +Play your favorite classic Nintendo, Sega, and Sony console games on Linux. +![](https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/open_gaming_games_roundup_news.png?itok=KM0ViL0f) + +The most common question I get on [my YouTube channel][1] and in person is what my favorite Linux distribution is. If I limit the answer to what I run on my desktops and laptops, my answer will typically be some form of an Ubuntu-based Linux distro. My honest answer to this question may surprise many. My favorite Linux distribution is actually [RetroPie][2]. + +As passionate as I am about Linux and open source software, I'm equally passionate about classic gaming, specifically video games produced in the '90s and earlier. I spend most of my surplus income on older games, and I now have a collection of close to a thousand games for over 20 gaming consoles. In my spare time, I raid flea markets, yard sales, estate sales, and eBay buying games for various consoles, including almost every iteration made by Nintendo, Sega, and Sony. There's something about classic games that I adore, a charm that seems lost in games released nowadays. + +Unfortunately, collecting retro games has its fair share of challenges. Cartridges with memory for save files will lose their charge over time, requiring the battery to be replaced. While it's not hard to replace save batteries (if you know how), it's still time-consuming. Games on CD-ROMs are subject to disc rot, which means that even if you take good care of them, they'll still lose data over time and become unplayable. Also, sometimes it's difficult to find replacement parts for some consoles. This wouldn't be so much of an issue if the majority of classic games were available digitally, but the vast majority are never re-released on a digital platform. + +### Gaming on RetroPie + +RetroPie is a great project and an asset to retro gaming enthusiasts like me. RetroPie is a Raspbian-based distribution designed for use on the Raspberry Pi (though it is possible to get it working on other platforms, such as a PC). RetroPie boots into a graphical interface that is completely controllable via a gamepad or joystick and allows you to easily manage digital copies (ROMs) of your favorite games. You can scrape information from the internet to organize your collection better and manage lists of favorite games, and the entire interface is very user-friendly and efficient. From the interface, you can launch directly into a game, then exit the game by pressing a combination of buttons on your gamepad. You rarely need a keyboard, unless you have to enter your WiFi password or manually edit configuration files. + +I use RetroPie to host a digital copy of every physical game I own in my collection. When I purchase a game from a local store or eBay, I also download the ROM. As a collector, this is very convenient. If I don't have a particular physical console within arms reach, I can boot up RetroPie and enjoy a game quickly without having to connect cables or clean cartridge contacts. There's still something to be said about playing a game on the original hardware, but if I'm pressed for time, RetroPie is very convenient. I also don't have to worry about dead save batteries, dirty cartridge contacts, disc rot, or any of the other issues collectors like me have to regularly deal with. I simply play the game. + +Also, RetroPie allows me to be very clever and utilize my technical know-how to achieve additional functionality that's not normally available. For example, I have three RetroPies set up, each of them synchronizing their files between each other by leveraging [Syncthing][3], a popular open source file synchronization tool. The synchronization happens automatically, and it means I can start a game on one television and continue in the same place on another unit since the save files are included in the synchronization. To take it a step further, I also back up my save and configuration files to [Backblaze B2][4], so I'm protected if an SD card becomes defective. + +### Setting up RetroPie + +Setting up RetroPie is very easy, and if you've ever set up a Raspberry Pi Linux distribution before (such as Raspbian) the process is essentially the same—you simply download the IMG file and flash it to your SD card by utilizing another tool, such as [Etcher][5], and insert it into your RetroPie. Then plug in an AC adapter and gamepad and hook it up to your television via HDMI. Optionally, you can buy a case to protect your RetroPie from outside elements and add visual appeal. Here is a listing of things you'll need to get started: + + * Raspberry Pi board (Model 3B+ or higher recommended) + * SD card (16GB or larger recommended) + * A USB gamepad + * UL-listed micro USB power adapter, at least 2.5 amp + + + +If you choose to add the optional Raspberry Pi case, I recommend the Super NES and Super Famicom themed cases from [RetroFlag][6]. Not only do these cases look cool, but they also have fully functioning power and reset buttons. This means you can configure the reset and power buttons to directly trigger the operating system's halt process, rather than abruptly terminating power. This definitely makes for a more professional experience, but it does require the installation of a special script. The instructions are on [RetroFlag's GitHub page][7]. Be wary: there are many cases available on Amazon and eBay of varying quality. Some of them are cheap knock-offs of RetroFlag cases, and others are just a lower quality overall. In fact, even cases by RetroFlag vary in quality—I had some power-distribution issues with the NES-themed case that made for an unstable experience. If in doubt, I've found that RetroFlag's Super NES and Super Famicom themed cases work very well. + +### Adding games + +When you boot RetroPie for the first time, it will resize the filesystem to ensure you have full access to the available space on your SD card and allow you to set up your gamepad. I can't give you links for game ROMs, so I'll leave that part up to you to figure out. When you've found them, simply add them to the RetroPie SD card in the designated folder, which would be located under **/home/pi/RetroPie/roms/ **. You can use your favorite tool for transferring the ROMs to the Pi, such as [SCP][8] in a terminal, [WinSCP][9], [Samba][10], etc. Once you've added the games, you can rescan them by pressing start and choosing the option to restart EmulationStation. When it restarts, it should automatically add menu entries for the ROMs you've added. That's basically all there is to it. + +(The rescan updates EmulationStation’s game inventory. If you don’t do that, it won’t list any newly added games you copy over.) + +Regarding the games' performance, your mileage will vary depending on which consoles you're emulating. For example, I've noticed that Sega Dreamcast games barely run at all, and most Nintendo 64 games will run sluggishly with a bad framerate. Many PlayStation Portable (PSP) games also perform inconsistently. However, all of the 8-bit and 16-bit consoles emulate seemingly perfectly—I haven't run into a single 8-bit or 16-bit game that doesn't run well. Surprisingly, games designed for the original PlayStation run great for me, which is a great feat considering the lower-performance potential of the Raspberry Pi. + +Overall, RetroPie's performance is great, but the Raspberry Pi is not as powerful as a gaming PC, so adjust your expectations accordingly. + +### Conclusion + +RetroPie is a fantastic open source project dedicated to preserving classic games and an asset to game collectors everywhere. Having a digital copy of my physical game collection is extremely convenient. If I were to tell my childhood self that one day I could have an entire game collection on one device, I probably wouldn't believe it. But RetroPie has become a staple in my household and provides hours of fun and enjoyment. + +If you want to see the parts I mentioned as well as a quick installation overview, I have [a video][11] on [my YouTube channel][12] that goes over the process and shows off some gameplay at the end. + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/19/1/retropie + +作者：[Jay LaCroix][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/jlacroix +[b]: https://github.com/lujun9972 +[1]: https://www.youtube.com/channel/UCxQKHvKbmSzGMvUrVtJYnUA +[2]: https://retropie.org.uk/ +[3]: https://syncthing.net/ +[4]: https://www.backblaze.com/b2/cloud-storage.html +[5]: https://www.balena.io/etcher/ +[6]: https://www.amazon.com/shop/learnlinux.tv?listId=1N9V89LEH5S8K +[7]: https://github.com/RetroFlag/retroflag-picase +[8]: https://en.wikipedia.org/wiki/Secure_copy +[9]: https://winscp.net/eng/index.php +[10]: https://www.samba.org/ +[11]: https://www.youtube.com/watch?v=D8V-KaQzsWM +[12]: http://www.youtube.com/c/LearnLinuxtv diff --git a/sources/tech/20190111 Top 5 Linux Distributions for Productivity.md b/sources/tech/20190111 Top 5 Linux Distributions for Productivity.md new file mode 100644 index 0000000000..fbd8b9d120 --- /dev/null +++ b/sources/tech/20190111 Top 5 Linux Distributions for Productivity.md @@ -0,0 +1,170 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Top 5 Linux Distributions for Productivity) +[#]: via: (https://www.linux.com/blog/learn/2019/1/top-5-linux-distributions-productivity) +[#]: author: (Jack Wallen https://www.linux.com/users/jlwallen) + +Top 5 Linux Distributions for Productivity +====== + +![](https://www.linux.com/sites/lcom/files/styles/rendered_file/public/productivity_main.jpg?itok=2IKyg_7_) + +I have to confess, this particular topic is a tough one to address. Why? First off, Linux is a productive operating system by design. Thanks to an incredibly reliable and stable platform, getting work done is easy. Second, to gauge effectiveness, you have to consider what type of work you need a productivity boost for. General office work? Development? School? Data mining? Human resources? You see how this question can get somewhat complicated. + +That doesn’t mean, however, that some distributions aren’t able to do a better job of configuring and presenting that underlying operating system into an efficient platform for getting work done. Quite the contrary. Some distributions do a much better job of “getting out of the way,” so you don’t find yourself in a work-related hole, having to dig yourself out and catch up before the end of day. These distributions help strip away the complexity that can be found in Linux, thereby making your workflow painless. + +Let’s take a look at the distros I consider to be your best bet for productivity. To help make sense of this, I’ve divided them into categories of productivity. That task itself was challenging, because everyone’s productivity varies. For the purposes of this list, however, I’ll look at: + + * General Productivity: For those who just need to work efficiently on multiple tasks. + + * Graphic Design: For those that work with the creation and manipulation of graphic images. + + * Development: For those who use their Linux desktops for programming. + + * Administration: For those who need a distribution to facilitate their system administration tasks. + + * Education: For those who need a desktop distribution to make them more productive in an educational environment. + + + + +Yes, there are more categories to be had, many of which can get very niche-y, but these five should fill most of your needs. + +### General Productivity + +For general productivity, you won’t get much more efficient than [Ubuntu][1]. The primary reason for choosing Ubuntu for this category is the seamless integration of apps, services, and desktop. You might be wondering why I didn’t choose Linux Mint for this category? Because Ubuntu now defaults to the GNOME desktop, it gains the added advantage of GNOME Extensions (Figure 1). + +![GNOME Clipboard][3] + +Figure 1: The GNOME Clipboard Indicator extension in action. + +[Used with permission][4] + +These extensions go a very long way to aid in boosting productivity (so Ubuntu gets the nod over Mint). But Ubuntu didn’t just accept a vanilla GNOME desktop. Instead, they tweaked it to make it slightly more efficient and user-friendly, out of the box. And because Ubuntu contains just the right mixture of default, out-of-the-box, apps (that just work), it makes for a nearly perfect platform for productivity. + +Whether you need to write a paper, work on a spreadsheet, code a new app, work on your company website, create marketing images, administer a server or network, or manage human resources from within your company HR tool, Ubuntu has you covered. The Ubuntu desktop distribution also doesn’t require the user to jump through many hoops to get things working … it simply works (and quite well). Finally, thanks to it’s Debian base, Ubuntu makes installing third-party apps incredibly easy. + +Although Ubuntu tends to be the go-to for nearly every list of “top distributions for X,” it’s very hard to argue against this particular distribution topping the list of general productivity distributions. + +### Graphic Design + +If you’re looking to up your graphic design productivity, you can’t go wrong with [Fedora Design Suite][5]. This Fedora respin was created by the team responsible for all Fedora-related art work. Although the default selection of apps isn’t a massive collection of tools, those it does include are geared specifically for the creation and manipulation of images. + +With apps like GIMP, Inkscape, Darktable, Krita, Entangle, Blender, Pitivi, Scribus, and more (Figure 2), you’ll find everything you need to get your image editing jobs done and done well. But Fedora Design Suite doesn’t end there. This desktop platform also includes a bevy of tutorials that cover countless subjects for many of the installed applications. For anyone trying to be as productive as possible, this is some seriously handy information to have at the ready. I will say, however, the tutorial entry in the GNOME Favorites is nothing more than a link to [this page][6]. + +![Fedora Design Suite Favorites][8] + +Figure 2: The Fedora Design Suite Favorites menu includes plenty of tools for getting your graphic design on. + +[Used with permission][4] + +Those that work with a digital camera will certainly appreciate the inclusion of the Entangle app, which allows you to control your DSLR from the desktop. + +### Development + +Nearly all Linux distributions are great platforms for programmers. However, one particular distributions stands out, above the rest, as one of the most productive tools you’ll find for the task. That OS comes from [System76][9] and it’s called [Pop!_OS][10]. Pop!_OS is tailored specifically for creators, but not of the artistic type. Instead, Pop!_OS is geared toward creators who specialize in developing, programming, and making. If you need an environment that is not only perfected suited for your development work, but includes a desktop that’s sure to get out of your way, you won’t find a better option than Pop!_OS (Figure 3). + +What might surprise you (given how “young” this operating system is), is that Pop!_OS is also one of the single most stable GNOME-based platforms you’ll ever use. This means Pop!_OS isn’t just for creators and makers, but anyone looking for a solid operating system. One thing that many users will greatly appreciate with Pop!_OS, is that you can download an ISO specifically for your video hardware. If you have Intel hardware, [download][10] the version for Intel/AMD. If your graphics card is NVIDIA, download that specific release. Either way, you are sure go get a solid platform for which to create your masterpiece. + +![Pop!_OS][12] + +Figure 3: The Pop!_OS take on GNOME Overview. + +[Used with permission][4] + +Interestingly enough, with Pop!_OS, you won’t find much in the way of pre-installed development tools. You won’t find an included IDE, or many other dev tools. You can, however, find all the development tools you need in the Pop Shop. + +### Administration + +If you’re looking to find one of the most productive distributions for admin tasks, look no further than [Debian][13]. Why? Because Debian is not only incredibly reliable, it’s one of those distributions that gets out of your way better than most others. Debian is the perfect combination of ease of use and unlimited possibility. On top of which, because this is the distribution for which so many others are based, you can bet if there’s an admin tool you need for a task, it’s available for Debian. Of course, we’re talking about general admin tasks, which means most of the time you’ll be using a terminal window to SSH into your servers (Figure 4) or a browser to work with web-based GUI tools on your network. Why bother making use of a desktop that’s going to add layers of complexity (such as SELinux in Fedora, or YaST in openSUSE)? Instead, chose simplicity. + +![Debian][15] + +Figure 4: SSH’ing into a remote server on Debian. + +[Used with permission][4] + +And because you can select which desktop you want (from GNOME, Xfce, KDE, Cinnamon, MATE, LXDE), you can be sure to have the interface that best matches your work habits. + +### Education + +If you are a teacher or student, or otherwise involved in education, you need the right tools to be productive. Once upon a time, there existed the likes of Edubuntu. That distribution never failed to be listed in the top of education-related lists. However, that distro hasn’t been updated since it was based on Ubuntu 14.04. Fortunately, there’s a new education-based distribution ready to take that title, based on openSUSE. This spin is called [openSUSE:Education-Li-f-e][16] (Linux For Education - Figure 5), and is based on openSUSE Leap 42.1 (so it is slightly out of date). + +openSUSE:Education-Li-f-e includes tools like: + + * Brain Workshop - A dual n-back brain exercise + + * GCompris - An educational software suite for young children + + * gElemental - A periodic table viewer + + * iGNUit - A general purpose flash card program + + * Little Wizard - Development environment for children based on Pascal + + * Stellarium - An astronomical sky simulator + + * TuxMath - An math tutor game + + * TuxPaint - A drawing program for young children + + * TuxType - An educational typing tutor for children + + * wxMaxima - A cross platform GUI for the computer algebra system + + * Inkscape - Vector graphics program + + * GIMP - Graphic image manipulation program + + * Pencil - GUI prototyping tool + + * Hugin - Panorama photo stitching and HDR merging program + + +![Education][18] + +Figure 5: The openSUSE:Education-Li-f-e distro has plenty of tools to help you be productive in or for school. + +[Used with permission][4] + +Also included with openSUSE:Education-Li-f-e is the [KIWI-LTSP Server][19]. The KIWI-LTSP Server is a flexible, cost effective solution aimed at empowering schools, businesses, and organizations all over the world to easily install and deploy desktop workstations. Although this might not directly aid the student to be more productive, it certainly enables educational institutions be more productive in deploying desktops for students to use. For more information on setting up KIWI-LTSP, check out the openSUSE [KIWI-LTSP quick start guide][20]. + +Learn more about Linux through the free ["Introduction to Linux" ][21]course from The Linux Foundation and edX. + +-------------------------------------------------------------------------------- + +via: https://www.linux.com/blog/learn/2019/1/top-5-linux-distributions-productivity + +作者：[Jack Wallen][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/jlwallen +[b]: https://github.com/lujun9972 +[1]: https://www.ubuntu.com/ +[2]: /files/images/productivity1jpg +[3]: https://www.linux.com/sites/lcom/files/styles/rendered_file/public/productivity_1.jpg?itok=yxez3X1w (GNOME Clipboard) +[4]: /licenses/category/used-permission +[5]: https://labs.fedoraproject.org/en/design-suite/ +[6]: https://fedoraproject.org/wiki/Design_Suite/Tutorials +[7]: /files/images/productivity2jpg +[8]: https://www.linux.com/sites/lcom/files/styles/rendered_file/public/productivity_2.jpg?itok=ke0b8qyH (Fedora Design Suite Favorites) +[9]: https://system76.com/ +[10]: https://system76.com/pop +[11]: /files/images/productivity3jpg-0 +[12]: https://www.linux.com/sites/lcom/files/styles/rendered_file/public/productivity_3_0.jpg?itok=8UkCUfsD (Pop!_OS) +[13]: https://www.debian.org/ +[14]: /files/images/productivity4jpg +[15]: https://www.linux.com/sites/lcom/files/styles/rendered_file/public/productivity_4.jpg?itok=c9yD3Xw2 (Debian) +[16]: https://en.opensuse.org/openSUSE:Education-Li-f-e +[17]: /files/images/productivity5jpg +[18]: https://www.linux.com/sites/lcom/files/styles/rendered_file/public/productivity_5.jpg?itok=oAFtV8nT (Education) +[19]: https://en.opensuse.org/Portal:KIWI-LTSP +[20]: https://en.opensuse.org/SDB:KIWI-LTSP_quick_start +[21]: https://training.linuxfoundation.org/linux-courses/system-administration-training/introduction-to-linux diff --git a/sources/tech/20190113 Editing Subtitles in Linux.md b/sources/tech/20190113 Editing Subtitles in Linux.md new file mode 100644 index 0000000000..1eaa6a68fd --- /dev/null +++ b/sources/tech/20190113 Editing Subtitles in Linux.md @@ -0,0 +1,168 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Editing Subtitles in Linux) +[#]: via: (https://itsfoss.com/editing-subtitles) +[#]: author: (Shirish https://itsfoss.com/author/shirish/) + +Editing Subtitles in Linux +====== + +I have been a world movie and regional movies lover for decades. Subtitles are the essential tool that have enabled me to enjoy the best movies in various languages and from various countries. + +If you enjoy watching movies with subtitles, you might have noticed that sometimes the subtitles are not synced or not correct. + +Did you know that you can edit subtitles and make them better? Let me show you some basic subtitle editing in Linux. + +![Editing subtitles in Linux][1] + +### Extracting subtitles from closed captions data + +Around 2012, 2013 I came to know of a tool called [CCEextractor.][2] As time passed, it has become one of the vital tools for me, especially if I come across a media file which has the subtitle embedded in it. + +CCExtractor analyzes video files and produces independent subtitle files from the closed captions data. + +CCExtractor is a cross-platform, free and open source tool. The tool has matured quite a bit from its formative years and has been part of [GSOC][3] and Google Code-in now and [then.][4] + +The tool, to put it simply, is more or less a set of scripts which work one after another in a serialized order to give you an extracted subtitle. + +You can follow the installation instructions for CCExtractor on [this page][5]. + +After installing when you want to extract subtitles from a media file, do the following: + +``` +ccextractor +``` + +The output of the command will be something like this: + +It basically scans the media file. In this case, it found that the media file is in malyalam and that the media container is an [.mkv][6] container. It extracted the subtitle file with the same name as the video file adding _eng to it. + +CCExtractor is a wonderful tool which can be used to enhance subtitles along with Subtitle Edit which I will share in the next section. + +``` +Interesting Read: There is an interesting synopsis of subtitles at [vicaps][7] which tells and shares why subtitles are important to us. It goes into quite a bit of detail of movie-making as well for those interested in such topics. +``` + +### Editing subtitles with SubtitleEditor Tool + +You probably are aware that most subtitles are in [.srt format][8] . The beautiful thing about this format is and was you could load it in your text editor and do little fixes in it. + +A srt file looks something like this when launched into a simple text-editor: + +The excerpt subtitle I have shared is from a pretty Old German Movie called [The Cabinet of Dr. Caligari (1920)][9] + +Subtitleeditor is a wonderful tool when it comes to editing subtitles. Subtitle Editor is and can be used to manipulate time duration, frame-rate of the subtitle file to be in sync with the media file, duration of breaks in-between and much more. I’ll share some of the basic subtitle editing here. + +![][10] + +First install subtitleeditor the same way you installed ccextractor, using your favorite installation method. In Debian, you can use this command: + +``` +sudo apt install subtitleeditor +``` + +When you have it installed, let’s see some of the common scenarios where you need to edit a subtitle. + +#### Manipulating Frame-rates to sync with Media file + +If you find that the subtitles are not synced with the video, one of the reasons could be the difference between the frame rates of the video file and the subtitle file. + +How do you know the frame rates of these files, then? + +To get the frame rate of a video file, you can use the mediainfo tool. You may need to install it first using your distribution’s package manager. + +Using mediainfo is simple: + +``` +$ mediainfo somefile.mkv | grep Frame + Format settings : CABAC / 4 Ref Frames + Format settings, ReFrames : 4 frames + Frame rate mode : Constant + Frame rate : 25.000 FPS + Bits/(Pixel*Frame) : 0.082 + Frame rate : 46.875 FPS (1024 SPF) +``` + +Now you can see that framerate of the video file is 25.000 FPS. The other Frame-rate we see is for the audio. While I can share why particular fps are used in Video-encoding, Audio-encoding etc. it would be a different subject matter. There is a lot of history associated with it. + +Next is to find out the frame rate of the subtitle file and this is a slightly complicated. + +Usually, most subtitles are in a zipped format. Unzipping the .zip archive along with the subtitle file which ends in something.srt. Along with it, there is usually also a .info file with the same name which sometime may have the frame rate of the subtitle. + +If not, then it usually is a good idea to go some site and download the subtitle from a site which has that frame rate information. For this specific German file, I will be using [Opensubtitle.org][11] + +As you can see in the link, the frame rate of the subtitle is 23.976 FPS. Quite obviously, it won’t play well with my video file with frame rate 25.000 FPS. + +In such cases, you can change the frame rate of the subtitle file using the Subtitle Editor tool: + +Select all the contents from the subtitle file by doing CTRL+A. Go to Timings -> Change Framerate and change frame rates from 23.976 fps to 25.000 fps or whatever it is that is desired. Save the changed file. + +![synchronize frame rates of subtitles in Linux][12] + +#### Changing the Starting position of a subtitle file + +Sometimes the above method may be enough, sometimes though it will not be enough. + +You might find some cases when the start of the subtitle file is different from that in the movie or a media file while the frame rate is the same. + +In such cases, do the following: + +Select all the contents from the subtitle file by doing CTRL+A. Go to Timings -> Select Move Subtitle. + +![Move subtitles using Subtitle Editor on Linux][13] + +Change the new Starting position of the subtitle file. Save the changed file. + +![Move subtitles using Subtitle Editor in Linux][14] + +If you wanna be more accurate, then use [mpv][15] to see the movie or media file and click on the timing, if you click on the timing bar which shows how much the movie or the media file has elapsed, clicking on it will also reveal the microsecond. + +I usually like to be accurate so I try to be as precise as possible. It is very difficult in MPV as human reaction time is imprecise. If I wanna be super accurate then I use something like [Audacity][16] but then that is another ball-game altogether as you can do so much more with it. That may be something to explore in a future blog post as well. + +#### Manipulating Duration + +Sometimes even doing both is not enough and you even have to shrink or add the duration to make it sync with the media file. This is one of the more tedious works as you have to individually fix the duration of each sentence. This can happen especially if you have variable frame rates in the media file (nowadays rare but you still get such files). + +In such a scenario, you may have to edit the duration manually and automation is not possible. The best way is either to fix the video file (not possible without degrading the video quality) or getting video from another source at a higher quality and then [transcode][17] it with the settings you prefer. This again, while a major undertaking I could shed some light on in some future blog post. + +### Conclusion + +What I have shared in above is more or less on improving on existing subtitle files. If you were to start a scratch you need loads of time. I haven’t shared that at all because a movie or any video material of say an hour can easily take anywhere from 4-6 hours or even more depending upon skills of the subtitler, patience, context, jargon, accents, native English speaker, translator etc. all of which makes a difference to the quality of the subtitle. + +I hope you find this interesting and from now onward, you’ll handle your subtitles slightly better. If you have any suggestions to add, please leave a comment below. + + +-------------------------------------------------------------------------------- + +via: https://itsfoss.com/editing-subtitles + +作者：[Shirish][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/shirish/ +[b]: https://github.com/lujun9972 +[1]: https://i0.wp.com/itsfoss.com/wp-content/uploads/2019/01/editing-subtitles-in-linux.jpeg?resize=800%2C450&ssl=1 +[2]: https://www.ccextractor.org/ +[3]: https://itsfoss.com/best-open-source-internships/ +[4]: https://www.ccextractor.org/public:codein:google_code-in_2018 +[5]: https://github.com/CCExtractor/ccextractor/wiki/Installation +[6]: https://en.wikipedia.org/wiki/Matroska +[7]: https://www.vicaps.com/blog/history-of-silent-movies-and-subtitles/ +[8]: https://en.wikipedia.org/wiki/SubRip#SubRip_text_file_format +[9]: https://www.imdb.com/title/tt0010323/ +[10]: https://i1.wp.com/itsfoss.com/wp-content/uploads/2018/12/subtitleeditor.jpg?ssl=1 +[11]: https://www.opensubtitles.org/en/search/sublanguageid-eng/idmovie-4105 +[12]: https://i1.wp.com/itsfoss.com/wp-content/uploads/2019/01/subtitleeditor-frame-rate-sync.jpg?resize=800%2C450&ssl=1 +[13]: https://i0.wp.com/itsfoss.com/wp-content/uploads/2019/01/Move-subtitles-Caligiri.jpg?resize=800%2C450&ssl=1 +[14]: https://i2.wp.com/itsfoss.com/wp-content/uploads/2019/01/move-subtitles.jpg?ssl=1 +[15]: https://itsfoss.com/mpv-video-player/ +[16]: https://www.audacityteam.org/ +[17]: https://en.wikipedia.org/wiki/Transcoding +[18]: https://i0.wp.com/itsfoss.com/wp-content/uploads/2019/01/editing-subtitles-in-linux.jpeg?fit=800%2C450&ssl=1 diff --git a/sources/tech/20190113 Get started with Joplin, a note-taking app.md b/sources/tech/20190113 Get started with Joplin, a note-taking app.md new file mode 100644 index 0000000000..2498435040 --- /dev/null +++ b/sources/tech/20190113 Get started with Joplin, a note-taking app.md @@ -0,0 +1,61 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Get started with Joplin, a note-taking app) +[#]: via: (https://opensource.com/article/19/1/productivity-tool-joplin) +[#]: author: (Kevin Sonney https://opensource.com/users/ksonney (Kevin Sonney)) + +Get started with Joplin, a note-taking app +====== +Learn how open source tools can help you be more productive in 2019. First up, Joplin. +![](https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/programming-code-keyboard-laptop.png?itok=pGfEfu2S) + +There seems to be a mad rush at the beginning of every year to find ways to be more productive. New Year's resolutions, the itch to start the year off right, and of course, an "out with the old, in with the new" attitude all contribute to this. And the usual round of recommendations is heavily biased towards closed source and proprietary software. It doesn't have to be that way. + +Here's the first of my picks for 19 new (or new-to-you) open source tools to help you be more productive in 2019. + +### Joplin + +In the realm of productivity tools, note-taking apps are VERY handy. Yes, you can use the open source [NixNote][1] to access [Evernote][2] notes, but it's still linked to the Evernote servers and still relies on a third party for security. And while you CAN export your Evernote notes from NixNote, the only format options are NixNote XML or PDF files. + +![](https://opensource.com/sites/default/files/uploads/joplin-1.png) + +Enter [Joplin][3]. Joplin is a NodeJS application that runs and stores notes locally, allows you to encrypt your notes and supports multiple sync methods. Joplin can run as a console or graphical application on Windows, Mac, and Linux. Joplin also has mobile apps for Android and iOS, meaning you can take your notes with you without a major hassle. Joplin even allows you to format notes with Markdown, HTML, or plain text. + +![](https://opensource.com/sites/default/files/uploads/joplin-3.png) + +One really nice thing about Joplin is it supports two kinds of notes: plain notes and to-do notes. Plain notes are what you expect—documents containing text. To-do notes, on the other hand, have a checkbox in the notes list that allows you to mark them "done." And since the to-do note is still a note, you can include lists, documentation, and additional to-do items in a to-do note. + +When using the GUI, you can toggle editor views between plain text, WYSIWYG, and a split screen showing both the source text and the rendered view. You can also specify an external editor in the GUI, making it easy to update notes with Vim, Emacs, or any other editor capable of handling text documents. + +![Joplin console version][5] + +Joplin in the console. + +The console interface is absolutely fantastic. While it lacks a WYSIWYG editor, it defaults to the text editor for your login. It also has a powerful command mode that allows you to do almost everything you can do in the GUI version. And it renders Markdown correctly in the viewer. + +You can group notes in notebooks and tag notes for easy grouping across your notebooks. And it even has built-in search, so you can find things if you forget where you put them. + +Overall, Joplin is a first-class note-taking app ([and a great alternative to Evernote][6]) that will help you be organized and more productive over the next year. + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/19/1/productivity-tool-joplin + +作者：[Kevin Sonney][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/ksonney (Kevin Sonney) +[b]: https://github.com/lujun9972 +[1]: http://nixnote.org/NixNote-Home/ +[2]: https://evernote.com/ +[3]: https://joplin.cozic.net/ +[4]: https://opensource.com/article/19/1/file/419776 +[5]: https://opensource.com/sites/default/files/uploads/joplin-2_0.png (Joplin console version) +[6]: https://opensource.com/article/17/12/joplin-open-source-evernote-alternative diff --git a/sources/tech/20190114 Get started with Wekan, an open source kanban board.md b/sources/tech/20190114 Get started with Wekan, an open source kanban board.md new file mode 100644 index 0000000000..3e2ee79ecc --- /dev/null +++ b/sources/tech/20190114 Get started with Wekan, an open source kanban board.md @@ -0,0 +1,64 @@ +[#]: collector: (lujun9972) +[#]: translator: (wwhio) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Get started with Wekan, an open source kanban board) +[#]: via: (https://opensource.com/article/19/1/productivity-tool-wekan) +[#]: author: (Kevin Sonney https://opensource.com/users/ksonney (Kevin Sonney)) + +Get started with Wekan, an open source kanban board +====== +In the second article in our series on open source tools that will make you more productive in 2019, check out Wekan. +![](https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/kanban-board.png?itok=tXC0dkKV) + +There seems to be a mad rush at the beginning of every year to find ways to be more productive. New Year's resolutions, the itch to start the year off right, and of course, an "out with the old, in with the new" attitude all contribute to this. And the usual round of recommendations is heavily biased towards closed source and proprietary software. It doesn't have to be that way. + +Here's the second of my picks for 19 new (or new-to-you) open source tools to help you be more productive in 2019. + +### Wekan + +[Kanban][1] boards are a mainstay of today's agile processes. And many of us (myself included) use them to organize not just our work but also our personal lives. I know several artists who use apps like [Trello][2] to keep track of their commision lists as well as what's in progress and what's complete. + +![](https://opensource.com/sites/default/files/uploads/wekan-1.png) + +But these apps are often linked to a work account or a commercial service. Enter [Wekan][3], an open source kanban board you can run locally or on the service of your choice. Wekan offers much of the same functionality as other Kanban apps, such as creating boards, lists, swimlanes, and cards, dragging and dropping between lists, assigning to users, labeling cards, and doing pretty much everything else you'd expect in a modern kanban board. + +![](https://opensource.com/sites/default/files/uploads/wekan-2.png) + +The thing that distinguishes Wekan from most other kanban boards is the built-in rules. While most other boards support emailing updates, Wekan allows you to set up triggers when taking actions on cards, checklists, and labels. + +![](https://opensource.com/sites/default/files/uploads/wekan-3.png) + +Wekan can then take actions like moving cards, updating labels, adding checklists, and sending emails. + +![](https://opensource.com/sites/default/files/uploads/wekan-4.png) + +Setting up Wekan locally is a snap—literally. If your desktop supports [Snapcraft][4] applications, installing is as easy as: + +``` +sudo snap install wekan +``` + +It also supports Docker, which means installing on a server is reasonably straightforward on most servers and desktops. + +Overall, if you want a nice kanban board that you can run yourself, Wekan has you covered. + + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/19/1/productivity-tool-wekan + +作者：[Kevin Sonney][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/ksonney (Kevin Sonney) +[b]: https://github.com/lujun9972 +[1]: https://en.wikipedia.org/wiki/Kanban +[2]: https://www.trello.com +[3]: https://wekan.github.io/ +[4]: https://snapcraft.io/ diff --git a/sources/tech/20190114 Hegemon - A Modular System And Hardware Monitoring Tool For Linux.md b/sources/tech/20190114 Hegemon - A Modular System And Hardware Monitoring Tool For Linux.md new file mode 100644 index 0000000000..28b5d5cd27 --- /dev/null +++ b/sources/tech/20190114 Hegemon - A Modular System And Hardware Monitoring Tool For Linux.md @@ -0,0 +1,139 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Hegemon – A Modular System And Hardware Monitoring Tool For Linux) +[#]: via: (https://www.2daygeek.com/hegemon-a-modular-system-and-hardware-monitoring-tool-for-linux/) +[#]: author: (Magesh Maruthamuthu https://www.2daygeek.com/author/magesh/) + +Hegemon – A Modular System And Hardware Monitoring Tool For Linux +====== + +I know that everybody is preferring for **[TOP Command][1]** to monitor system utilization. + +It’s one of the best and native command which used by vast of Linux administrators. + +In Linux there is an alternative for everything respective of packages. + +There are many utilities are available for this purpose in Linux and i prefer **[HTOP Command][2]**. + +If you want to know about other alternatives, i would suggest you to navigate to the each link to know more about it. + +Those are htop, CorFreq, glances, atop, Dstat, Gtop, Linux Dash, Netdata, Monit, etc. + +All these tools only allow us to monitor system utilization and not for the system hardware’s. + +But Hegemon is allow us to monitor both in the single dashboard. + +If you are looking for system hardware monitoring then i would suggest you to check **[lm_sensors][3]** and **[s-tui Stress Terminal UI][4]** utilities. + +### What’s Hegemon? + +Hegemon is a work-in-progress modular system monitor written in safe Rust. + +It allow users to monitor both utilization in a single dashboard. It’s system utilization and hardware temperatures. + +### Currently Available Features in Hegemon + + * Monitor CPU and memory usage, temperatures, and fan speeds + * Expand any data stream to reveal a more detailed graph and additional information + * Adjustable update interval + * Clean MVC architecture with good code quality + * Unit tests + + + +### Planned Features include + + * macOS and BSD support (only Linux is supported at the moment) + * Monitor disk and network I/O, GPU usage (maybe), and more + * Select and reorder data streams + * Mouse control + + + +### How to Install Hegemon in Linux? + +Hegemon is requires Rust 1.26 or later and the development files for libsensors. So, make sure these packages were installed before your perform Hegemon installation. + +libsensors library package is available in most of the distribution official repository so, use the following command to install it. + +For **`Debian/Ubuntu`** systems, use **[APT-GET Command][5]** or **[APT Command][6]** to install libsensors on your systems. + +``` +# apt install lm_sensors-devel +``` + +For **`Fedora`** system, use **[DNF Package Manager][7]** to install libsensors on your system. + +``` +# dnf install libsensors4-dev +``` + +Run the following command to install Rust programming language and follow the instruction. Navigate to the following URL if you want handy tutorials for **[Rust installation][8]**. + +``` +$ curl https://sh.rustup.rs -sSf | sh +``` + +If you have successfully installed Rust. Run the following command to install Hegemon. + +``` +$ cargo install hegemon +``` + +### How to Lunch Hegemon in Linux? + +Once you successfully install Hegemon package. Run run the below command to launch it. + +``` +$ hegemon +``` + +![][10] + +I was facing an issue when i was launching the “Hegemon” application due to libsensors.so.4 libraries issue. + +``` +$ hegemon +error while loading shared libraries: libsensors.so.4: cannot open shared object file: No such file or directory manjaro +``` + +I’m using Manjaro 18.04. It has the libsensors.so & libsensors.so.5 shared libraries and not for libsensors.so.4. So, i just created the following symlink to fix the issue. + +``` +$ sudo ln -s /usr/lib/libsensors.so /usr/lib/libsensors.so.4 +``` + +Here is the sample gif file which was taken from my Lenovo-Y700 laptop. +![][11] + +By default it shows only overall summary and if you would like to see the detailed output then you need to expand the each section. See the expanded output with Hegemon. +![][12] + +-------------------------------------------------------------------------------- + +via: https://www.2daygeek.com/hegemon-a-modular-system-and-hardware-monitoring-tool-for-linux/ + +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/top-command-examples-to-monitor-server-performance/ +[2]: https://www.2daygeek.com/linux-htop-command-linux-system-performance-resource-monitoring-tool/ +[3]: https://www.2daygeek.com/view-check-cpu-hard-disk-temperature-linux/ +[4]: https://www.2daygeek.com/s-tui-stress-terminal-ui-monitor-linux-cpu-temperature-frequency/ +[5]: https://www.2daygeek.com/apt-get-apt-cache-command-examples-manage-packages-debian-ubuntu-systems/ +[6]: https://www.2daygeek.com/apt-command-examples-manage-packages-debian-ubuntu-systems/ +[7]: https://www.2daygeek.com/dnf-command-examples-manage-packages-fedora-system/ +[8]: https://www.2daygeek.com/how-to-install-rust-programming-language-in-linux/ +[9]: data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7 +[10]: https://www.2daygeek.com/wp-content/uploads/2019/01/hegemon-a-modular-system-and-hardware-monitoring-tool-for-linux-1.png +[11]: https://www.2daygeek.com/wp-content/uploads/2019/01/hegemon-a-modular-system-and-hardware-monitoring-tool-for-linux-2a.gif +[12]: https://www.2daygeek.com/wp-content/uploads/2019/01/hegemon-a-modular-system-and-hardware-monitoring-tool-for-linux-3.png diff --git a/sources/tech/20190114 How To Move Multiple File Types Simultaneously From Commandline.md b/sources/tech/20190114 How To Move Multiple File Types Simultaneously From Commandline.md new file mode 100644 index 0000000000..1b342b12ef --- /dev/null +++ b/sources/tech/20190114 How To Move Multiple File Types Simultaneously From Commandline.md @@ -0,0 +1,96 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (How To Move Multiple File Types Simultaneously From Commandline) +[#]: via: (https://www.ostechnix.com/how-to-move-multiple-file-types-simultaneously-from-commandline/) +[#]: author: (SK https://www.ostechnix.com/author/sk/) + +How To Move Multiple File Types Simultaneously From Commandline +====== + +![](https://www.ostechnix.com/wp-content/uploads/2019/01/Move-Multiple-File-Types-720x340.png) + +The other day I was wondering how can I move (not copy) multiple file types from directory to another. I already knew how to [**find and copy certain type of files from one directory to another**][1]. But, I don’t know how to move multiple file types simultaneously. If you’re ever in a situation like this, I know a easy way to do it from commandline in Unix-like systems. + +### Move Multiple File Types Simultaneously + +Picture this scenario.You have multiple type of files, for example .pdf, .doc, .mp3, .mp4, .txt etc., on a directory named **‘dir1’**. Let us take a look at the dir1 contents: + +``` +$ ls dir1 +file.txt image.jpg mydoc.doc personal.pdf song.mp3 video.mp4 +``` + +You want to move some of the file types (not all of them) to different location. For example, let us say you want to move doc, pdf and txt files only to another directory named **‘dir2’** in one go. + +To copy .doc, .pdf and .txt files from dir1 to dir2 simultaneously, the command would be: + +``` +$ mv dir1/*.{doc,pdf,txt} dir2/ +``` + +It’s easy, isn’t it? + +Now, let us check the contents of dir2: + +``` +$ ls dir2/ +file.txt mydoc.doc personal.pdf +``` + +See? Only the file types .doc, .pdf and .txt from dir1 have been moved to dir2. + +![][3] + +You can add as many file types as you want to inside curly braces in the above command to move them across different directories. The above command just works fine for me on Bash. + +Another way to move multiple file types is go to the source directory i.e dir1 in our case: + +``` +$ cd ~/dir1 +``` + +And, move file types of your choice to the destination (E.g dir2) as shown below. + +``` +$ mv *.doc *.txt *.pdf /home/sk/dir2/ +``` + +To move all files having a particular extension, for example **.doc** only, run: + +``` +$ mv dir1/*.doc dir2/ +``` + +For more details, refer man pages. + +``` +$ man mv +``` + +Moving a few number of same or different file types is easy! You could do this with couple mouse clicks in GUI mode or use a one-liner command in CLI mode. However, If you have thousands of different file types in a directory and wanted to move multiple file types to different directory in one go, it would be a cumbersome task. To me, the above method did the job easily! If you know any other one-liner commands to move multiple file types at a time, please share it in the comment section below. I will check and update the guide accordingly. + +And, that’s all for now. Hope this was useful. More good stuffs to come. Stay tuned! + +Cheers! + + + +-------------------------------------------------------------------------------- + +via: https://www.ostechnix.com/how-to-move-multiple-file-types-simultaneously-from-commandline/ + +作者：[SK][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.ostechnix.com/author/sk/ +[b]: https://github.com/lujun9972 +[1]: https://www.ostechnix.com/find-copy-certain-type-files-one-directory-another-linux/ +[2]: data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7 +[3]: http://www.ostechnix.com/wp-content/uploads/2019/01/mv-command.gif diff --git a/sources/tech/20190114 How to Build a Netboot Server, Part 4.md b/sources/tech/20190114 How to Build a Netboot Server, Part 4.md new file mode 100644 index 0000000000..aadd3c0b01 --- /dev/null +++ b/sources/tech/20190114 How to Build a Netboot Server, Part 4.md @@ -0,0 +1,632 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (How to Build a Netboot Server, Part 4) +[#]: via: (https://fedoramagazine.org/how-to-build-a-netboot-server-part-4/) +[#]: author: (Gregory Bartholomew https://fedoramagazine.org/author/glb/) + +How to Build a Netboot Server, Part 4 +====== +![](https://fedoramagazine.org/wp-content/uploads/2018/11/netboot4-816x345.jpg) + +One significant limitation of the netboot server built in this series is the operating system image being served is read-only. Some use cases may require the end user to modify the image. For example, an instructor may want to have the students install and configure software packages like MariaDB and Node.js as part of their course walk-through. + +An added benefit of writable netboot images is the end user’s “personalized” operating system can follow them to different workstations they may use at later times. + +### Change the Bootmenu Application to use HTTPS + +Create a self-signed certificate for the bootmenu application: + +``` +$ sudo -i +# MY_NAME=$( .*#listen => ['https://$MY_NAME:443?cert=$MY_TLSD/$MY_NAME.pem\&key=$MY_TLSD/$MY_NAME.key\&ciphers=AES256-SHA256:AES128-SHA256:AES256-SHA:AES128-SHA'],#" /opt/bootmenu/bootmenu.conf +``` + +Note the ciphers have been restricted to [those currently supported by iPXE][1]. + +GnuTLS requires the “CAP_DAC_READ_SEARCH” capability, so add it to the bootmenu application’s systemd service: + +``` +# sed -i '/^AmbientCapabilities=/ s/$/ CAP_DAC_READ_SEARCH/' /etc/systemd/system/bootmenu.service +# sed -i 's/Serves iPXE Menus over HTTP/Serves iPXE Menus over HTTPS/' /etc/systemd/system/bootmenu.service +# systemctl daemon-reload +``` + +Now, add an exception for the bootmenu service to the firewall and restart the service: + +``` +# MY_SUBNET=192.0.2.0 +# MY_PREFIX=24 +# firewall-cmd --add-rich-rule="rule family='ipv4' source address='$MY_SUBNET/$MY_PREFIX' service name='https' accept" +# firewall-cmd --runtime-to-permanent +# systemctl restart bootmenu.service +``` + +Use wget to verify it’s working: + +``` +$ MY_NAME=server-01.example.edu +$ MY_TLSD=/opt/bootmenu/tls +$ wget -q --ca-certificate=$MY_TLSD/$MY_NAME.pem -O - https://$MY_NAME/menu +``` + +### Add HTTPS to iPXE + +Update init.ipxe to use HTTPS. Then recompile the ipxe bootloader with options to embed and trust the self-signed certificate you created for the bootmenu application: + +``` +$ echo '#define DOWNLOAD_PROTO_HTTPS' >> $HOME/ipxe/src/config/local/general.h +$ sed -i 's/^chain http:/chain https:/' $HOME/ipxe/init.ipxe +$ cp $MY_TLSD/$MY_NAME.pem $HOME/ipxe +$ cd $HOME/ipxe/src +$ make clean +$ make bin-x86_64-efi/ipxe.efi EMBED=../init.ipxe CERT="../$MY_NAME.pem" TRUST="../$MY_NAME.pem" +``` + +You can now copy the HTTPS-enabled iPXE bootloader out to your clients and test that everything is working correctly: + +``` +$ cp $HOME/ipxe/src/bin-x86_64-efi/ipxe.efi $HOME/esp/efi/boot/bootx64.efi +``` + +### Add User Authentication to Mojolicious + +Create a PAM service definition for the bootmenu application: + +``` +# dnf install -y pam_krb5 +# echo 'auth required pam_krb5.so' > /etc/pam.d/bootmenu +``` + +Add a library to the bootmenu application that uses the Authen-PAM perl module to perform user authentication: + +``` +# dnf install -y perl-Authen-PAM; +# MY_MOJO=/opt/bootmenu +# mkdir $MY_MOJO/lib +# cat << 'END' > $MY_MOJO/lib/PAM.pm +package PAM; + +use Authen::PAM; + +sub auth { + my $success = 0; + + my $username = shift; + my $password = shift; + + my $callback = sub { + my @res; + while (@_) { + my $code = shift; + my $msg = shift; + my $ans = ""; + + $ans = $username if ($code == PAM_PROMPT_ECHO_ON()); + $ans = $password if ($code == PAM_PROMPT_ECHO_OFF()); + + push @res, (PAM_SUCCESS(), $ans); + } + push @res, PAM_SUCCESS(); + + return @res; + }; + + my $pamh = new Authen::PAM('bootmenu', $username, $callback); + + { + last unless ref $pamh; + last unless $pamh->pam_authenticate() == PAM_SUCCESS; + $success = 1; + } + + return $success; +} + +return 1; +END +``` + +The above code is taken almost verbatim from the Authen::PAM::FAQ man page. + +Redefine the bootmenu application so it returns a netboot template only if a valid username and password are supplied: + +``` +# cat << 'END' > $MY_MOJO/bootmenu.pl +#!/usr/bin/env perl + +use lib 'lib'; + +use PAM; +use Mojolicious::Lite; +use Mojolicious::Plugins; +use Mojo::Util ('url_unescape'); + +plugin 'Config'; + +get '/menu'; +get '/boot' => sub { + my $c = shift; + + my $instance = $c->param('instance'); + my $username = $c->param('username'); + my $password = $c->param('password'); + + my $template = 'menu'; + + { + last unless $instance =~ /^fc[[:digit:]]{2}$/; + last unless $username =~ /^[[:alnum:]]+$/; + last unless PAM::auth($username, url_unescape($password)); + $template = $instance; + } + + return $c->render(template => $template); +}; + +app->start; +END +``` + +The bootmenu application now looks for the lib directory relative to its WorkingDirectory. However, by default the working directory is set to the root directory of the server for systemd units. Therefore, you must update the systemd unit to set WorkingDirectory to the root of the bootmenu application instead: + +``` +# sed -i "/^RuntimeDirectory=/ a WorkingDirectory=$MY_MOJO" /etc/systemd/system/bootmenu.service +# systemctl daemon-reload +``` + +Update the templates to work with the redefined bootmenu application: + +``` +# cd $MY_MOJO/templates +# MY_BOOTMENU_SERVER=$( fc$i.html.ep; grep "^kernel\|initrd" menu.html.ep | grep "fc$i" >> fc$i.html.ep; echo "boot || chain https://$MY_BOOTMENU_SERVER/menu" >> fc$i.html.ep; sed -i "/^:f$i$/,/^boot /c :f$i\nlogin\nchain https://$MY_BOOTMENU_SERVER/boot?instance=fc$i\&username=\${username}\&password=\${password:uristring} || goto failed" menu.html.ep; done +``` + +The result of the last command above should be three files similar to the following: + +**menu.html.ep** : + +``` +#!ipxe + +set timeout 5000 + +:menu +menu iPXE Boot Menu +item --key 1 lcl 1. Microsoft Windows 10 +item --key 2 f29 2. RedHat Fedora 29 +item --key 3 f28 3. RedHat Fedora 28 +choose --timeout ${timeout} --default lcl selected || goto shell +set timeout 0 +goto ${selected} + +:failed +echo boot failed, dropping to shell... +goto shell + +:shell +echo type 'exit' to get the back to the menu +set timeout 0 +shell +goto menu + +:lcl +exit + +:f29 +login +chain https://server-01.example.edu/boot?instance=fc29&username=${username}&password=${password:uristring} || goto failed + +:f28 +login +chain https://server-01.example.edu/boot?instance=fc28&username=${username}&password=${password:uristring} || goto failed +``` + +**fc29.html.ep** : + +``` +#!ipxe +kernel --name kernel.efi ${prefix}/vmlinuz-4.19.5-300.fc29.x86_64 initrd=initrd.img ro ip=dhcp rd.peerdns=0 nameserver=192.0.2.91 nameserver=192.0.2.92 root=/dev/disk/by-path/ip-192.0.2.158:3260-iscsi-iqn.edu.example.server-01:fc29-lun-1 netroot=iscsi:192.0.2.158::::iqn.edu.example.server-01:fc29 console=tty0 console=ttyS0,115200n8 audit=0 selinux=0 quiet +initrd --name initrd.img ${prefix}/initramfs-4.19.5-300.fc29.x86_64.img +boot || chain https://server-01.example.edu/menu +``` + +**fc28.html.ep** : + +``` +#!ipxe +kernel --name kernel.efi ${prefix}/vmlinuz-4.19.3-200.fc28.x86_64 initrd=initrd.img ro ip=dhcp rd.peerdns=0 nameserver=192.0.2.91 nameserver=192.0.2.92 root=/dev/disk/by-path/ip-192.0.2.158:3260-iscsi-iqn.edu.example.server-01:fc28-lun-1 netroot=iscsi:192.0.2.158::::iqn.edu.example.server-01:fc28 console=tty0 console=ttyS0,115200n8 audit=0 selinux=0 quiet +initrd --name initrd.img ${prefix}/initramfs-4.19.3-200.fc28.x86_64.img +boot || chain https://server-01.example.edu/menu +``` + +Now, restart the bootmenu application and verify authentication is working: + +``` +# systemctl restart bootmenu.service +``` + +### Make the iSCSI Target Writeable + +Now that user authentication works through iPXE, you can create per-user, writeable overlays on top of the read-only image on demand when users connect. Using a [copy-on-write][2] overlay has three advantages over simply copying the original image file for each user: + + 1. The copy can be created very quickly. This allows creation on-demand. + 2. The copy does not increase the disk usage on the server. Only what the user writes to their personal copy of the image is stored in addition to the original image. + 3. Since most sectors for each copy are the same sectors on the server’s storage, they’ll likely already be loaded in RAM when subsequent users access their copies of the operating system. This improves the server’s performance because RAM is faster than disk I/O. + + + +One potential pitfall of using copy-on-write is that once overlays are created, the images on which they are overlayed must not be changed. If they are changed, all the overlays will be corrupted. Then the overlays must be deleted and replaced with new, blank overlays. Even simply mounting the image file in read-write mode can cause sufficient filesystem updates to corrupt the overlays. + +Due to the potential for the overlays to be corrupted if the original image is modified, mark the original image as immutable by running: + +``` +# chattr +i +``` + +You can use lsattr to view the status of the immutable flag and use to chattr -i unset the immutable flag. While the immutable flag is set, even the root user or a system process running as root cannot modify or delete the file. + +Begin by stopping the tgtd.service so you can change the image files: + +``` +# systemctl stop tgtd.service +``` + +It’s normal for this command to take a minute or so to stop when there are connections still open. + +Now, remove the read-only iSCSI export. Then update the readonly-root configuration file in the template so the image is no longer read-only: + +``` +# MY_FC=fc29 +# rm -f /etc/tgt/conf.d/$MY_FC.conf +# TEMP_MNT=$(mktemp -d) +# mount /$MY_FC.img $TEMP_MNT +# sed -i 's/^READONLY=yes$/READONLY=no/' $TEMP_MNT/etc/sysconfig/readonly-root +# sed -i 's/^Storage=volatile$/#Storage=auto/' $TEMP_MNT/etc/systemd/journald.conf +# umount $TEMP_MNT +``` + +Journald was changed from logging to volatile memory back to its default (log to disk if /var/log/journal exists) because a user reported his clients would freeze with an out-of-memory error due to an application generating excessive system logs. The downside to setting logging to disk is that extra write traffic is generated by the clients, and might burden your netboot server with unnecessary I/O. You should decide which option — log to memory or log to disk — is preferable depending on your environment. + +Since you won’t make any further changes to the template image, set the immutable flag on it and restart the tgtd.service: + +``` +# chattr +i /$MY_FC.img +# systemctl start tgtd.service +``` + +Now, update the bootmenu application: + +``` +# cat << 'END' > $MY_MOJO/bootmenu.pl +#!/usr/bin/env perl + +use lib 'lib'; + +use PAM; +use Mojolicious::Lite; +use Mojolicious::Plugins; +use Mojo::Util ('url_unescape'); + +plugin 'Config'; + +get '/menu'; +get '/boot' => sub { + my $c = shift; + + my $instance = $c->param('instance'); + my $username = $c->param('username'); + my $password = $c->param('password'); + + my $chapscrt; + my $template = 'menu'; + + { + last unless $instance =~ /^fc[[:digit:]]{2}$/; + last unless $username =~ /^[[:alnum:]]+$/; + last unless PAM::auth($username, url_unescape($password)); + last unless $chapscrt = `sudo scripts/mktgt $instance $username`; + $template = $instance; + } + + return $c->render(template => $template, username => $username, chapscrt => $chapscrt); +}; + +app->start; +END +``` + +This new version of the bootmenu application calls a custom mktgt script which, on success, returns a random [CHAP][3] password for each new iSCSI target that it creates. The CHAP password prevents one user from mounting another user’s iSCSI target by indirect means. The app only returns the correct iSCSI target password to a user who has successfully authenticated. + +The mktgt script is prefixed with sudo because it needs root privileges to create the target. + +The $username and $chapscrt variables also pass to the render command so they can be incorporated into the templates returned to the user when necessary. + +Next, update our boot templates so they can read the username and chapscrt variables and pass them along to the end user. Also update the templates to mount the root filesystem in rw (read-write) mode: + +``` +# cd $MY_MOJO/templates +# sed -i "s/:$MY_FC/:$MY_FC-<%= \$username %>/g" $MY_FC.html.ep +# sed -i "s/ netroot=iscsi:/ netroot=iscsi:<%= \$username %>:<%= \$chapscrt %>@/" $MY_FC.html.ep +# sed -i "s/ ro / rw /" $MY_FC.html.ep +``` + +After running the above commands, you should have boot templates like the following: + +``` +#!ipxe +kernel --name kernel.efi ${prefix}/vmlinuz-4.19.5-300.fc29.x86_64 initrd=initrd.img rw ip=dhcp rd.peerdns=0 nameserver=192.0.2.91 nameserver=192.0.2.92 root=/dev/disk/by-path/ip-192.0.2.158:3260-iscsi-iqn.edu.example.server-01:fc29-<%= $username %>-lun-1 netroot=iscsi:<%= $username %>:<%= $chapscrt %>@192.0.2.158::::iqn.edu.example.server-01:fc29-<%= $username %> console=tty0 console=ttyS0,115200n8 audit=0 selinux=0 quiet +initrd --name initrd.img ${prefix}/initramfs-4.19.5-300.fc29.x86_64.img +boot || chain https://server-01.example.edu/menu +``` + +NOTE: If you need to view the boot template after the variables have been [interpolated][4], you can insert the “shell” command on its own line just before the “boot” command. Then, when you netboot your client, iPXE gives you an interactive shell where you can enter “imgstat” to view the parameters being passed to the kernel. If everything looks correct, you can type “exit” to leave the shell and continue the boot process. + +Now allow the bootmenu user to run the mktgt script (and only that script) as root via sudo: + +``` +# echo "bootmenu ALL = NOPASSWD: $MY_MOJO/scripts/mktgt *" > /etc/sudoers.d/bootmenu +``` + +The bootmenu user should not have write access to the mktgt script or any other files under its home directory. All the files under /opt/bootmenu should be owned by root, and should not be writable by any user other than root. + +Sudo does not work well with systemd’s DynamicUser option, so create a normal user account and set the systemd service to run as that user: + +``` +# useradd -r -c 'iPXE Boot Menu Service' -d /opt/bootmenu -s /sbin/nologin bootmenu +# sed -i 's/^DynamicUser=true$/User=bootmenu/' /etc/systemd/system/bootmenu.service +# systemctl daemon-reload +``` + +Finally, create a directory for the copy-on-write overlays and create the mktgt script that manages the iSCSI targets and their overlayed backing stores: + +``` +# mkdir /$MY_FC.cow +# mkdir $MY_MOJO/scripts +# cat << 'END' > $MY_MOJO/scripts/mktgt +#!/usr/bin/env perl + +# if another instance of this script is running, wait for it to finish +"$ENV{FLOCKER}" eq 'MKTGT' or exec "env FLOCKER=MKTGT flock /tmp $0 @ARGV"; + +# use "RETURN" to print to STDOUT; everything else goes to STDERR by default +open(RETURN, '>&', STDOUT); +open(STDOUT, '>&', STDERR); + +my $instance = shift or die "instance not provided"; +my $username = shift or die "username not provided"; + +my $img = "/$instance.img"; +my $dir = "/$instance.cow"; +my $top = "$dir/$username"; + +-f "$img" or die "'$img' is not a file"; +-d "$dir" or die "'$dir' is not a directory"; + +my $base; +die unless $base = `losetup --show --read-only --nooverlap --find $img`; +chomp $base; + +my $size; +die unless $size = `blockdev --getsz $base`; +chomp $size; + +# create the per-user sparse file if it does not exist +if (! -e "$top") { + die unless system("dd if=/dev/zero of=$top status=none bs=512 count=0 seek=$size") == 0; +} + +# create the copy-on-write overlay if it does not exist +my $cow="$instance-$username"; +my $dev="/dev/mapper/$cow"; +if (! -e "$dev") { + my $over; + die unless $over = `losetup --show --nooverlap --find $top`; + chomp $over; + die unless system("echo 0 $size snapshot $base $over p 8 | dmsetup create $cow") == 0; +} + +my $tgtadm = '/usr/sbin/tgtadm --lld iscsi'; + +# get textual representations of the iscsi targets +my $text = `$tgtadm --op show --mode target`; +my @targets = $text =~ /(?:^T.*\n)(?:^ .*\n)*/mg; + +# convert the textual representations into a hash table +my $targets = {}; +foreach (@targets) { + my $tgt; + my $sid; + + foreach (split /\n/) { + /^Target (\d+)(?{ $tgt = $targets->{$^N} = [] })/; + /I_T nexus: (\d+)(?{ $sid = $^N })/; + /Connection: (\d+)(?{ push @{$tgt}, [ $sid, $^N ] })/; + } +} + +my $hostname; +die unless $hostname = `hostname`; +chomp $hostname; + +my $target = 'iqn.' . join('.', reverse split('\.', $hostname)) . ":$cow"; + +# find the target id corresponding to the provided target name and +# close any existing connections to it +my $tid = 0; +foreach (@targets) { + next unless /^Target (\d+)(?{ $tid = $^N }): $target$/m; + foreach (@{$targets->{$tid}}) { + die unless system("$tgtadm --op delete --mode conn --tid $tid --sid $_->[0] --cid $_->[1]") == 0; + } +} + +# create a new target if an existing one was not found +if ($tid == 0) { + # find an available target id + my @ids = (0, sort keys %{$targets}); + $tid = 1; while ($ids[$tid]==$tid) { $tid++ } + + # create the target + die unless -e "$dev"; + die unless system("$tgtadm --op new --mode target --tid $tid --targetname $target") == 0; + die unless system("$tgtadm --op new --mode logicalunit --tid $tid --lun 1 --backing-store $dev") == 0; + die unless system("$tgtadm --op bind --mode target --tid $tid --initiator-address ALL") == 0; +} + +# (re)set the provided target's chap password +my $password = join('', map(chr(int(rand(26))+65), 1..8)); +my $accounts = `$tgtadm --op show --mode account`; +if ($accounts =~ / $username$/m) { + die unless system("$tgtadm --op delete --mode account --user $username") == 0; +} +die unless system("$tgtadm --op new --mode account --user $username --password $password") == 0; +die unless system("$tgtadm --op bind --mode account --tid $tid --user $username") == 0; + +# return the new password to the iscsi target on stdout +print RETURN $password; +END +# chmod +x $MY_MOJO/scripts/mktgt +``` + +The above script does five things: + + 1. It creates the /.cow/ sparse file if it does not already exist. + 2. It creates the /dev/mapper/- device node that serves as the copy-on-write backing store for the iSCSI target if it does not already exist. + 3. It creates the iqn.:- iSCSI target if it does not exist. Or, if the target does exist, it closes any existing connections to it because the image can only be opened in read-write mode from one place at a time. + 4. It (re)sets the chap password on the iqn.:- iSCSI target to a new random value. + 5. It prints the new chap password on [standard output][5] if all of the previous tasks compeleted successfully. + + + +You should be able to test the mktgt script from the command line by running it with valid test parameters. For example: + +``` +# echo `$MY_MOJO/scripts/mktgt fc29 jsmith` +``` + +When run from the command line, the mktgt script should print out either the eight-character random password for the iSCSI target if it succeeded or the line number on which something went wrong if it failed. + +On occasion, you may want to delete an iSCSI target without having to stop the entire service. For example, a user might inadvertently corrupt their personal image, in which case you would need to systematically undo everything that the above mktgt script does so that the next time they log in they will get a copy of the original image. + +Below is an rmtgt script that undoes, in reverse order, what the above mktgt script did: + +``` +# mkdir $HOME/bin +# cat << 'END' > $HOME/bin/rmtgt +#!/usr/bin/env perl + +@ARGV >= 2 or die "usage: $0 [+d|+f]\n"; + +my $instance = shift; +my $username = shift; + +my $rmd = ($ARGV[0] eq '+d'); #remove device node if +d flag is set +my $rmf = ($ARGV[0] eq '+f'); #remove sparse file if +f flag is set +my $cow = "$instance-$username"; + +my $hostname; +die unless $hostname = `hostname`; +chomp $hostname; + +my $tgtadm = '/usr/sbin/tgtadm'; +my $target = 'iqn.' . join('.', reverse split('\.', $hostname)) . ":$cow"; + +my $text = `$tgtadm --op show --mode target`; +my @targets = $text =~ /(?:^T.*\n)(?:^ .*\n)*/mg; + +my $targets = {}; +foreach (@targets) { + my $tgt; + my $sid; + + foreach (split /\n/) { + /^Target (\d+)(?{ $tgt = $targets->{$^N} = [] })/; + /I_T nexus: (\d+)(?{ $sid = $^N })/; + /Connection: (\d+)(?{ push @{$tgt}, [ $sid, $^N ] })/; + } +} + +my $tid = 0; +foreach (@targets) { + next unless /^Target (\d+)(?{ $tid = $^N }): $target$/m; + foreach (@{$targets->{$tid}}) { + die unless system("$tgtadm --op delete --mode conn --tid $tid --sid $_->[0] --cid $_->[1]") == 0; + } + die unless system("$tgtadm --op delete --mode target --tid $tid") == 0; + print "target $tid deleted\n"; + sleep 1; +} + +my $dev = "/dev/mapper/$cow"; +if ($rmd or ($rmf and -e $dev)) { + die unless system("dmsetup remove $cow") == 0; + print "device node $dev deleted\n"; +} + +if ($rmf) { + my $sf = "/$instance.cow/$username"; + die "sparse file $sf not found" unless -e "$sf"; + die unless system("rm -f $sf") == 0; + die unless not -e "$sf"; + print "sparse file $sf deleted\n"; +} +END +# chmod +x $HOME/bin/rmtgt +``` + +For example, to use the above script to completely remove the fc29-jsmith target including its backing store device node and its sparse file, run the following: + +``` +# rmtgt fc29 jsmith +f +``` + +Once you’ve verified that the mktgt script is working properly, you can restart the bootmenu service. The next time someone netboots, they should receive a personal copy of the the netboot image they can write to: + +``` +# systemctl restart bootmenu.service +``` + +Users should now be able to modify the root filesystem as demonstrated in the below screenshot: + +![][6] + + +-------------------------------------------------------------------------------- + +via: https://fedoramagazine.org/how-to-build-a-netboot-server-part-4/ + +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]: http://ipxe.org/crypto +[2]: https://en.wikipedia.org/wiki/Copy-on-write +[3]: https://en.wikipedia.org/wiki/Challenge-Handshake_Authentication_Protocol +[4]: https://en.wikipedia.org/wiki/String_interpolation +[5]: https://en.wikipedia.org/wiki/Standard_streams +[6]: https://fedoramagazine.org/wp-content/uploads/2018/11/netboot-fix-pam_mount-1024x819.png diff --git a/sources/tech/20190114 Turn a Raspberry Pi 3B- into a PriTunl VPN.md b/sources/tech/20190114 Turn a Raspberry Pi 3B- into a PriTunl VPN.md new file mode 100644 index 0000000000..b7e55e0efb --- /dev/null +++ b/sources/tech/20190114 Turn a Raspberry Pi 3B- into a PriTunl VPN.md @@ -0,0 +1,113 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Turn a Raspberry Pi 3B+ into a PriTunl VPN) +[#]: via: (https://opensource.com/article/19/1/pritunl-vpn-raspberry-pi) +[#]: author: (Stephen Bancroft https://opensource.com/users/stevereaver) + +Turn a Raspberry Pi 3B+ into a PriTunl VPN +====== +PriTunl is a VPN solution for small businesses and individuals who want private access to their network. + +![](https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/life-raspberrypi_0.png?itok=Kczz87J2) + +[PriTunl][1] is a fantastic VPN terminator solution that's perfect for small businesses and individuals who want a quick and simple way to access their network privately. It's open source, and the basic free version is more than enough to get you started and cover most simple use cases. There is also a paid enterprise version with advanced features like Active Directory integration. + +### Special considerations on Raspberry Pi 3B+ + +PriTunl is generally simple to install, but this project—turning a Raspberry Pi 3B+ into a PriTunl VPN appliance—adds some complexity. For one thing, PriTunl is supplied only as AMD64 and i386 binaries, but the 3B+ uses ARM architecture. This means you must compile your own binaries from source. That's nothing to be afraid of; it can be as simple as copying and pasting a few commands and watching the terminal for a short while. + +Another problem: PriTunl seems to require 64-bit architecture. I found this out when I got errors when I tried to compile PriTunl on my Raspberry Pi's 32-bit operating system. Fortunately, Ubuntu's beta version of 18.04 for ARM64 boots on the Raspberry Pi 3B+. + +Also, the Raspberry Pi 3B+ uses a different bootloader from other Raspberry Pi models. This required a complicated set of steps to install and update the necessary files to get a Raspberry Pi 3B+ to boot. + +### Installing PriTunl + +You can overcome these problems by installing a 64-bit operating system on the Raspberry Pi 3B+ before installing PriTunl. I'll assume you have basic knowledge of how to get around the Linux command line and a Raspberry Pi. + +Start by opening a terminal and downloading the Ubuntu 18.04 ARM64 beta release by entering: + +``` +$ wget http://cdimage.ubuntu.com/releases/18.04/beta/ubuntu-18.04-beta-preinstalled-server-arm64+raspi3.img.xz +``` + +Unpack the download: + +``` +$ xz -d ubuntu-18.04-beta-preinstalled-server-arm64+raspi3.xz +``` + +Insert the SD card you'll use with your Raspberry Pi into your desktop or laptop computer. Your computer will assign the SD card a drive letter—something like **/dev/sda** or **/dev/sdb**. Enter the **dmesg** command and examine the last lines of the output to find out the card's drive assignment. + +**Be VERY CAREFUL with the next step! I can't stress that enough; if you get the drive assignment wrong, you could destroy your system.** + +Write the image to your SD card with the following command, changing **< DRIVE>** to your SD card's drive assignment (obtained in the previous step): + +``` +$ dd if=ubuntu-18.04-beta-preinstalled-server-arm64+raspi3.img of= bs=8M +``` + +After it finishes, insert the SD card into your Pi and power it up. Make sure the Pi is connected to your network, then log in with username/password combination ubuntu/ubuntu. + +Enter the following commands on your Pi to install a few things to prepare to compile PriTunl: + +``` +$ sudo apt-get -y install build-essential git bzr python python-dev python-pip net-tools openvpn bridge-utils psmisc golang-go libffi-dev mongodb +``` + +There are a few changes from the standard PriTunl source [installation instructions on GitHub][2]. Make sure you are logged into your Pi and **sudo** to root: + +``` +$ sudo su - +``` + +This should leave you in root's home directory. To install PriTunl version 1.29.1914.98, enter (per GitHub): + +``` +export VERSION=1.29.1914.98 +tee -a ~/.bashrc << EOF +export GOPATH=\$HOME/go +export PATH=/usr/local/go/bin:\$PATH +EOF +source ~/.bashrc +mkdir pritunl && cd pritunl +go get -u github.com/pritunl/pritunl-dns +go get -u github.com/pritunl/pritunl-web +sudo ln -s ~/go/bin/pritunl-dns /usr/bin/pritunl-dns +sudo ln -s ~/go/bin/pritunl-web /usr/bin/pritunl-web +wget https://github.com/pritunl/pritunl/archive/$VERSION.tar.gz +tar -xf $VERSION.tar.gz +cd pritunl-$VERSION +python2 setup.py build +pip install -r requirements.txt +python2 setup.py install --prefix=/usr/local +``` + +Now the MongoDB and PriTunl systemd units should be ready to start up. Assuming you're still logged in as root, enter: + +``` +systemctl daemon-reload +systemctl start mongodb pritunl +systemctl enable mongodb pritunl +``` + +That's it! You're ready to hit PriTunl's browser user interface and configure it by following PriTunl's [installation and configuration instructions][3] on its website. + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/19/1/pritunl-vpn-raspberry-pi + +作者：[Stephen Bancroft][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/stevereaver +[b]: https://github.com/lujun9972 +[1]: https://pritunl.com/ +[2]: https://github.com/pritunl/pritunl +[3]: https://docs.pritunl.com/docs/configuration-5 diff --git a/sources/tech/20190115 Linux Tools- The Meaning of Dot.md b/sources/tech/20190115 Linux Tools- The Meaning of Dot.md new file mode 100644 index 0000000000..5e18c7603d --- /dev/null +++ b/sources/tech/20190115 Linux Tools- The Meaning of Dot.md @@ -0,0 +1,183 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Linux Tools: The Meaning of Dot) +[#]: via: (https://www.linux.com/blog/learn/2019/1/linux-tools-meaning-dot) +[#]: author: (Paul Brown https://www.linux.com/users/bro66) + +Linux Tools: The Meaning of Dot +====== + +![](https://www.linux.com/sites/lcom/files/styles/rendered_file/public/psychedelic-dot.jpg?itok=giKEHvwQ) + +Let's face it: writing one-liners and scripts using shell commands can be confusing. Many of the names of the tools at your disposal are far from obvious in terms of what they do ( _grep_ , _tee_ and _awk_ , anyone?) and, when you combine two or more, the resulting "sentence" looks like some kind of alien gobbledygook. + +None of the above is helped by the fact that many of the symbols you use to build a chain of instructions can mean different things depending on their context. + +### Location, location, location + +Take the humble dot (`.`) for example. Used with instructions that are expecting the name of a directory, it means "this directory" so this: + +``` +find . -name "*.jpg" +``` + +translates to " _find in this directory (and all its subdirectories) files that have names that end in`.jpg`_ ". + +Both `ls .` and `cd .` act as expected, so they list and "change" to the current directory, respectively, although including the dot in these two cases is not necessary. + +Two dots, one after the other, in the same context (i.e., when your instruction is expecting a directory path) means " _the directory immediately above the current one_ ". If you are in _/home/your_directory_ and run + +``` +cd .. +``` + +you will be taken to _/home_. So, you may think this still kind of fits into the “dots represent nearby directories” narrative and is not complicated at all, right? + +How about this, then? If you use a dot at the beginning of a directory or file, it means the directory or file will be hidden: + +``` +$ touch somedir/file01.txt somedir/file02.txt somedir/.secretfile.txt +$ ls -l somedir/ +total 0 +-rw-r--r-- 1 paul paul 0 Jan 13 19:57 file01.txt +-rw-r--r-- 1 paul paul 0 Jan 13 19:57 file02.txt +$ # Note how there is no .secretfile.txt in the listing above +$ ls -la somedir/ +total 8 +drwxr-xr-x 2 paul paul 4096 Jan 13 19:57 . +drwx------ 48 paul paul 4096 Jan 13 19:57 .. +-rw-r--r-- 1 paul paul 0 Jan 13 19:57 file01.txt +-rw-r--r-- 1 paul paul 0 Jan 13 19:57 file02.txt +-rw-r--r-- 1 paul paul 0 Jan 13 19:57 .secretfile.txt +$ # The -a option tells ls to show "all" files, including the hidden ones +``` + +And then there's when you use `.` as a command. Yep! You heard me: `.` is a full-fledged command. It is a synonym of `source` and you use that to execute a file in the current shell, as opposed to running a script some other way (which usually mean Bash will spawn a new shell in which to run it). + +Confused? Don't worry -- try this: Create a script called _myscript_ that contains the line + +``` +myvar="Hello" +``` + +and execute it the regular way, that is, with `sh myscript` (or by making the script executable with `chmod a+x myscript` and then running `./myscript`). Now try and see the contents of `myvar` with `echo $myvar` (spoiler: You will get nothing). This is because, when your script plunks " _Hello_ " into `myvar`, it does so in a separate bash shell instance. When the script ends, the spawned instance disappears and control returns to the original shell, where `myvar` never even existed. + +However, if you run _myscript_ like this: + +``` +. myscript +``` + +`echo $myvar` will print _Hello_ to the command line. + +You will often use the `.` (or `source`) command after making changes to your _.bashrc_ file, [like when you need to expand your `PATH` variable][1]. You use `.` to make the changes available immediately in your current shell instance. + +### Double Trouble + +Just like the seemingly insignificant single dot has more than one meaning, so has the double dot. Apart from pointing to the parent of the current directory, the double dot (`..`) is also used to build sequences. + +Try this: + +``` +echo {1..10} +``` + +It will print out the list of numbers from 1 to 10. In this context, `..` means " _starting with the value on my left, count up to the value on my right_ ". + +Now try this: + +``` +echo {1..10..2} +``` + +You'll get _1 3 5 7 9_. The `..2` part of the command tells Bash to print the sequence, but not one by one, but two by two. In other words, you'll get all the odd numbers from 1 to 10. + +It works backwards, too: + +``` +echo {10..1..2} +``` + +You can also pad your numbers with 0s. Doing: + +``` +echo {000..121..2} +``` + +will print out every even number from 0 to 121 like this: + +``` +000 002 004 006 ... 050 052 054 ... 116 118 120 +``` + +But how is this sequence-generating construct useful? Well, suppose one of your New Year's resolutions is to be more careful with your accounts. As part of that, you want to create directories in which to classify your digital invoices of the last 10 years: + +``` +mkdir {2009..2019}_Invoices +``` + +Job done. + +Or maybe you have a hundreds of numbered files, say, frames extracted from a video clip, and, for whatever reason, you want to remove only every third frame between the frames 43 and 61: + +``` +rm frame_{043..61..3} +``` + +It is likely that, if you have more than 100 frames, they will be named with padded 0s and look like this: + +``` +frame_000 frame_001 frame_002 ... +``` + +That’s why you will use `043` in your command instead of just `43`. + +### Curly~Wurly + +Truth be told, the magic of sequences lies not so much in the double dot as in the sorcery of the curly braces (`{}`). Look how it works for letters, too. Doing: + +``` +touch file_{a..z}.txt +``` + +creates the files _file_a.txt_ through _file_z.txt_. + +You must be careful, however. Using a sequence like `{Z..a}` will run through a bunch of non-alphanumeric characters (glyphs that are neither numbers or letters) that live between the uppercase alphabet and the lowercase one. Some of these glyphs are unprintable or have a special meaning of their own. Using them to generate names of files could lead to a whole bevy of unexpected and potentially unpleasant effects. + +One final thing worth pointing out about sequences encased between `{...}` is that they can also contain lists of strings: + +``` +touch {blahg, splurg, mmmf}_file.txt +``` + +Creates _blahg_file.txt_ , _splurg_file.txt_ and _mmmf_file.txt_. + +Of course, in other contexts, the curly braces have different meanings (surprise!). But that is the stuff of another article. + +### Conclusion + +Bash and the utilities you can run within it have been shaped over decades by system administrators looking for ways to solve very particular problems. To say that sysadmins and their ways are their own breed of special would be an understatement. Consequently, as opposed to other languages, Bash was not designed to be user-friendly, easy or even logical. + +That doesn't mean it is not powerful -- quite the contrary. Bash's grammar and shell tools may be inconsistent and sprawling, but they also provide a dizzying range of ways to do everything you can possibly imagine. It is like having a toolbox where you can find everything from a power drill to a spoon, as well as a rubber duck, a roll of duct tape, and some nail clippers. + +Apart from fascinating, it is also fun to discover all you can achieve directly from within the shell, so next time we will delve ever deeper into how you can build bigger and better Bash command lines. + +Until then, have fun! + +-------------------------------------------------------------------------------- + +via: https://www.linux.com/blog/learn/2019/1/linux-tools-meaning-dot + +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/blog/learn/2018/12/bash-variables-environmental-and-otherwise diff --git a/translated/talk/20170921 The Rise and Rise of JSON.md b/translated/talk/20170921 The Rise and Rise of JSON.md deleted file mode 100644 index e5eb3b2dd6..0000000000 --- a/translated/talk/20170921 The Rise and Rise of JSON.md +++ /dev/null @@ -1,102 +0,0 @@ -[#]: collector: (lujun9972) -[#]: translator: (runningwater) -[#]: reviewer: ( ) -[#]: publisher: ( ) -[#]: subject: (The Rise and Rise of JSON) -[#]: via: ( https://twobithistory.org/2017/09/21/the-rise-and-rise-of-json.html) -[#]: author: (https://twobithistory.org) -[#]: url: ( ) - -JSON 的兴起与崛起 -====== -JSON 已经占领了全世界。当今，任何两个应用程序彼此通过网络通信时，它们很有可能在使用 JSON。它已被所有大型企业所采用：十大最受欢迎的 web API 接口（主要由 Google、Facebook 和 Twitter 提供的）列表中，仅仅只有一个 API 接口是以 XML 的格式开放数据的。Twitter 给这个 API 添加了一个说明性示例：XML 格式的支持到 2013 年结束，到时候会发布一个新版本的 API，取消 XML 格式，转而使用 JSON。JSON 也在程序编码级别和文件存储上被广泛采用：在 Stack Overflow（一个面向程序员的问答网站）上，现在更多的是关于 JSON 的问题，而不是其他的数据交换格式。 - -![][1] - -XML 仍然在很多地方存在。在网页上有 SVG 和 RSS 订阅服务、Atom 提供商。Android 开发者想要获得用户权限许可时，需要在其 APP 的 `manifest` 文件中声明。此文件是 XML 格式的。XML 的替代品也不仅仅只有 JSON，现在有很多人在使用 YAML 或 Google 的 Protocol Buffers 等技术，但这些技术的受欢迎程度远不如 JSON。目前来看，JSON 是应用程序在网络之间通信的首选协议格式。 -考虑到自 2005 年来网站编程世界对 “异步 JavaScript 和 XML” 而非 “异步 JavaScript 和 JSON” 技术潜力的垂涎欲滴状态，你可以发现 JSON 在其中的主导地位是如此让人惊讶。当然了，这可能与这两种通信格式的受欢迎程度无关，仅反映出 “AJAX” 似乎比 “AJAJ” 更具吸引力。但是，即使在 2015 年时有好些人已经用 JSON 来取代 XML 了（实际上还没有很多人），我们不禁要问 XML 的噩运来的如此之快，以至于短短十年左右，“异步 JavaScript 和 XML” 这个名称就成为一个很讽刺的误称。那个十年发生了什么？JSON 怎么会在那么多应用程序中取代了 XML？现在被全世界工程师和系统所使用、依赖的这种数据格式是谁提出的？ - -### JSON 之诞生 - -2001 年 4 月，首个 JSON 格式的消息被发送。此消息是从旧金山湾区某车库的一台计算机发出的，这是计算机历史上重要的的时刻。Douglas Crockford 和 Chip Morningstar 是一家名为 State Software 的技术咨询公司的联合创始人，他们当时聚集在 Morningstar 的车库里测试某个想法，发出了此消息。 - -在 “AJAX” 这个术语被创造之前, Crockford 和 Morningstar 就已经在尝试构建好用的 AJAX 应用程序了。可是浏览器对其兼容性不好。他们想要在初始页面加载后就将数据传递给应用程序，但其目标要针对所有的浏览器，这就实现不了。 - -这在今天看来不太可信，但是要记得 2001 年的时候 Internet Explorer（IE）代表了网页浏览器的最前沿技术产品。早在 1999 年的时候，Internet Explorer 5 就支持 `XMLHttpRequest 对象原型`，开发者可以使用名为 ActiveX 的框架来访问此对象。 Crockford 和 Morningstar 可能是使用此技术来获取数据，但是在 Netscape 4 中（这是他们想要支持的另一种浏览器）就无法使用这种解决方案。为此 Crockford 和 Morningstar 只得开发不同的系统程序以兼容不同的浏览器。 - -第一条 JSON 消息如下所示： - -``` - -``` - -消息中只有一小部分类似于今天我们所知的 JSON，本身其实是一个包含有 JavaScript 的 HTML 文档。类似于 JSON 的部分只是传递给名为`receive（）` 的函数的 JavaScript 对象。 - -Crockford 和 Morningstar 决定滥用 HTML 的 frame，以发送数据。敲入 URL 返回的 HTML 文档（如上所示）可以指向一个 frame 标签。当接收到 HTML 时，JavaScript 代码段一运行，就可以把数据对象如实地传递回应用程序。只要小心的回避浏览器保护策略，即子窗口不允许访问父窗口，这种技术就可以正常运行无误。可以看到 Crockford 和 Mornginstar 通过明确地设置文档域这种方法来达到其目的。（这种基于 frame 的技术，有时称为隐藏 frame 技术，通常在90年代后期，即广泛使用 XMLHttpRequest 技术之前使用。） - -关于第一个 JSON 消息的惊人之处在于它显然不是第一次就使用新的数据格式。它仅仅是 JavaScript！实际上，以此使用 JavaScript 的想法如此简单，Crockford 自己也说过他不是第一个这样做的人。他声称 Netscape 公司的某人早在 1996 年就使用 JavaScript 数组文字来交换信息。因为消息就是 JavaScript 本身，其不需要任何特殊解析工作，JavaScript 解释器就可搞定一切。 - -最初的 JSON 信息实际上与 JavaScript 解释器发生了冲突。JavaScript 使用了大量的单词来做为保留字（ECMAScript 6 版本的就有 64 个保留字），Crockford 和 Morningstar 无意中在其 JSON 中引入了一个保留字。他们使用了 `do` 这个关键字，但 `do` 是解释器中的保留字。因为 JavaScript 使用的保留字太多了，Crockford 做了决定：既然不可避免的要使用到这些保留字，那就要求所有的 JSON 关键字都加上引号。被引起来的关键字会被 JavaScript 解释器识别成字符串，其意味着那些保留字也可以放心安全的使用。这就为什么今天 JSON 关键字都要用引号引起来的原因。 - -Crockford 和 Morningstar 意识到这技术可以应用于各类应用系统。想给其命名为 “JSML”，即 JavaScript 标记语言，但发现这个缩写已经被叫做 Java 标记语言的所使用了。因此他们决定采用 “JavaScript Object Notation” 或 JSON 命名。他们开始向客户推销，但很快发现客户不愿意冒险使用缺乏官方规范的未知技术。所以 Crockford 决定写一个规范。 - -2002 年，Crockford 买下了 [JSON.org][2] 域名，放上了 JSON 语法及一个解释器的实例例子。网站仍然在运行，现在已经包含有 2013 年正式批准的 JSON ECMA 标准的显著链接。在网站建立后，Crockford 并没有过多的推广，但很快发现很多人都在提交各种不同编程语言的 JSON 解析器实现。JSON 的血统明显与 JavaScript 相关联，但很明显 JSON 非常适合于不同语言之间的数据交换。 - - -### AJAX 导致的误会 - -2005 年，JSON 有了一次大扩展。那一年，一位名叫 Jesse James Garrett 的网页设计师和开发人员在博客文章中创造了 “AJAX” 一词。他很谨慎地强调：AJAX 并不是新技术，而是 “好几种技术以某种强大的新方式汇集，其中的各技术各自发展。” AJAX 是 Garrett 给 Web 应用程序开发的新方法（其正获得青睐）的命名。他的博客文章接着描述了开发人员如何利用 JavaScript 和 XMLHttpRequest 对象构建新的应用程序，这些应用程序比传统的网页更具响应性和状态性。 他还举了 Gmail 和 Flickr的网站已经使用 AJAX 技术的例子。 - -当然了，“AJAX” 中的 “X” 代表 XML。但在随后的问答帖子中，Garrett 指出，JSON 可以完全替代 XML。他写道：虽然 XML 是 AJAX 客户端进行数据输入输出的最完善的技术，但要实现同样的效果，也可以使用像 JavaScript Object Notation （JSON）或任何类似的结构数据方法等技术。 - -开发者确实发现在构建 AJAX 应用程序时可以很容易的使用 JSON，并且很多人也开始喜欢上 XML。具有讽刺意味的是，对 AJAX 的兴趣逐渐的导致了 JSON 的普及。大约在这个时候，JSON 引起了博客圈的注意。 - -2006 年，Dave Winer，一位高产的博主，也是许多基于 XML 技术（如 RSS 和 XML-RPC）的后端开发工程师，他抱怨到 JSON 毫无疑问的正在重新发明 XML。虽然他认为数据交换格式之间的竞争不会导致某一技术的消亡，其写到： - -> 让我们来比较下重构某结构数据的深度及难度，由于某些原因（我很想听听原因），XML 自身做的并不好，所以毫无疑问地，我会写一个例程来解析 JSON 格式的数据。谁想干这荒谬之事？查找一棵树然后把节点串起来。可以立马试试。 - -很容易理解 Winer 的挫败感，事实上并没有太多人喜欢 XML。甚至 Winer 也说过他不喜欢 XML。但 XML 已被设计成一个可供任何人使用，并且几乎能想象到的事情都可以做到的系统。最终，XML 实际上是一门元语言，允许你为特定应用程序自定义特定域的语言。如 RSS、web feed 技术和 SOAP(简单对象访问协议)就是自定义的例子。Winer 认为由于通用交换格式所带来的好处，努力达成共识就很重要了。XML 的灵活性应该能满足任何人的需求，然而这里是 JSON 格式，其并不比 XML 更具优势，但其抛弃了 XML 中不好的设计，可以使 XML 更加的灵活。 - -Crockford 阅读了 Winer 的这篇文章并留下了评论。为了回应 JSON 重新发明 XML 的指责，Crockford 写到：重造轮子的好处是可以得到一个更好的轮子。 - -### JSON 与 XML 对比 - -到 2014 年，JSON 已经由 ECMA 标准和 RFC 官方正式认可。它有自己的 MIME 类型。JSON 已经进入了大联盟时代。 - -为什么 JSON 比 XML 更受欢迎？ - -在 [JSON.org][2] 网站上，Crockford 总结了一些 JSON 的优势。他写到，JSON 的语法很小，其结构可预测，因此 JSON 更容易被人类和机器理解。其他博主不得不关注 XML 的冗长啰嗦及“尖括号负担”。XML 中每个开始标记都必须与结束标记匹配，这意味着 XML 文档包含大量的冗余信息。在未压缩时，XML 文档的体积比同信息量 JSON 文档的体积大很多，但是，更重要的，这也使 XML 文档更难以阅读。 - -Crockford 还声称 JSON 的另一个巨大优势是其被设计为数据交换格式。从一开始，它的目的就是在应用程序间传递结构化信息的。而 XML 呢，虽然也可以使用来传递数据，但其最初被设计为文档标记语言。它从 SGML（通用标准标记语言）演变而来，后来又从称为 Scribe 的标记语言是发展，旨在发展成类似于 LaTeX 一样的文字处理系统。XML 中，一个标签可以包含有所谓的“混合内容”或包含有围绕单词、短语的内嵌标签的文本。这会让人浮现出一副用红蓝笔记录的手稿画面，这是标记语言核心思想的形象比喻。另一方面，JSON 不支持对混合内容模型清晰构建，但也意味着它的结构足够简单。一份文档最好的建模就是一棵树，但 JSON 抛弃了文档的思想，Crockford 将 JSON 抽象限制为字典和数组，这是所有程序员构建程序时都会使用的最基本也最熟悉的元素。 - -最后，我认为人们不喜欢 XML 是因为它让人困惑。它让人迷惑的地方就是有很多不同的风格。乍一看，XML 本身及其子语言（如 RSS、ATOM、SOAP 或 SVG）之间的界限并不明显。通用 XML 文档创建的版本做为第一个基线，然后特定的子语言 XML 版本应该在这基础上变动。这就有需要变化需要考虑的了，特别是跟 JSON 做比较。JSON 的是如此简单，以至于 JSON 新版本规范甚至都不用重写。XML 的设计者试图将 XML 做为唯一的数据交换格式以支配所有格式，会掉入那个经典程序员的陷阱：过度工程化。XML 非常笼统及概念化，所以很难于简单的使用。 - -在 2000 年的时候，推出了一场活动，以使 HTML 符合 XML 标准。发布了一份符合 XML 标准的 HTML 开发规范，这就此后很出名的 XHTML。虽然一些浏览器供应商立即开始支持这个新标准，但也很明显，大部分基于 HTML 技术的开发者不愿意改变他们的习惯。新标准要求对 XHTML 文档进行严格的验证，而不是基于 HTML 的基准。但大多的网站都是依赖于 HTML 的宽容规则的。到 2009 年的时候，试图编写第二版本的 XHTML 标准已经流产，因为未来已清晰可见， HTML 将会发展为 HTML5（一种不强制要求接受 XML 规则的标准）。 - -如果 XHTML 的努力取得了成功，那么 XML 可能会成为其设计者希望的通用数据格式。想象一下，HTML 文档和 API 响应具有完全相同结构的世界。在这样的世界中，JSON 可能不会像现在一样普遍存在。但我读懂了, XHTML 的失败是 XML 阵营的一种道德失败。如果 XML 不是 HTML 的最佳工具，那么为了其他应用程序，也许会有更好的工具出现。在这个世界，我们的世界，很容易看到像 JSON 格式这样的足够简单、量体裁衣才能获得更大的成功。 - -如果你喜欢这博文，每两周会更新一次！ 请在 Twitter 上关注 [@TwoBitHistory] [3] 或订阅 [RSS feed] [4], 以确保得到更新的通知。 - --------------------------------------------------------------------------------- - -via: https://twobithistory.org/2017/09/21/the-rise-and-rise-of-json.html - -作者：[Two-Bit History][a] -选题：[lujun9972][b] -译者：[runningwater](https://github.com/runningwater) -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://twobithistory.org -[b]: https://github.com/lujun9972 -[1]: https://twobithistory.org/images/json.svg -[2]: http://JSON.org -[3]: https://twitter.com/TwoBitHistory -[4]: https://twobithistory.org/feed.xml diff --git a/translated/talk/20180419 5 guiding principles you should know before you design a microservice.md b/translated/talk/20180419 5 guiding principles you should know before you design a microservice.md new file mode 100644 index 0000000000..6eee610d0b --- /dev/null +++ b/translated/talk/20180419 5 guiding principles you should know before you design a microservice.md @@ -0,0 +1,155 @@ +设计微服务架构前，您应该了解的5项指导原则 +====== + +![](https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/BIZ_OpenInnovation.png?itok=l29msbql) +对于从微服务开始的团队来说，最大的挑战之一就是坚持金发姑娘原则（The *Goldilocks principle*）：不要太大， 不要太小，不能太紧密耦合。之所以是挑战的原因是会对究竟什么是设计良好的微服务感到疑惑。 + +数十家 CTOs 通过采访分享了他们的经验， 这些对话说明了设计良好的微服务的五个特点。本文将帮助指导团队设计微服务。（有关详细信息， 请查看即将出版的书籍 [Microservices for Startups][1]）。本文将简要介绍微服务的边界和主观的 ”规则“，以避免在深入了解五个特征之前就开始指导您的微服务设计。 + +### 微服务边界 + + [core benefits of developing new systems with microservices][2] （开发具有微服务的新系统的核心优势）其中之一是该体系结构允许开发人员独立构建和修改单个组件， 但在最大限度地减少每个 API 之间的回调数量方面可能会出现问题。 根据 Chris McFadden 的解决方法，[SparkPost ][3] 的工程副总裁，应用适当的服务边界去解决问题。 + +关于边界， 与 domain-driven design (DDD)—a framework for microservices （域驱动设计--微服务框架）有时难以理解和抽象的概念形成鲜明对比，本文重点介绍了与我们行业的一些顶级 CTOs 建立明确定义的微服务边界的实用原则。 + +### 避免主观的 ”规则“ + +如果您阅读了足够多的关于设计和创建微服务的建议，您一定会遇到下面的一些 ”规则“。 尽管将它们用作创建微服务的指南很有吸引力， 但加入这些主观规则并不是思考确定微服务的边界的原则性方式。 + +#### ”微服务应该有 X 行代码“ + +让我们直说：微服务中有多少行代码没有限制。微服务不会因为您写了几行额外的代码而突然变成一个巨无霸。关键是要确保服务中的代码具有很高的内聚性 （稍后将对此进行更多介绍）。 + +#### “将每个功能转换为微服务” + +如果函数基于三个输入值计算某些内容并返回结果，它是否是微服务的理想候选项？它是否应该是单独可部署应用程序？这确实取决于函数是什么以及它是如何服务于整个系统。将每个函数转换为微服务在您的内容中可能根本没有意义。 + +其他主观规则包括不考虑整个内容的规则， 例如团队的经验、 DevOps （Development和Operations的组合词）容量、服务正在执行的操作以及数据的可用性需求。 + +### 精心设计的服务的5个特点 + +如果您读过关于微服务的文章， 您无疑会遇到关于什么是设计良好的服务的建议。简单地说， 高内聚和低耦合。如果您不熟悉这些概念， 有许多文章需要查看 [many][4] [articles][5] 。虽然他们提供了合理的建议，但这些概念是相当抽象的。下面， 基于与经验丰富的 CTOs 的对话， 在创建设计良好的微服务时需要牢记的关键特征。 + +#### #1: 不与其他服务共享数据库表 + +在 SparkPost 的早期， Chris McFadden 和他的团队必须解决一个问题，，每个 SaaS 生意（Software-as-a-Service，软件即服务）都要面对的：他们需要提供基本服务，如身份验证、帐户管理和计费。 + +为了解决这个问题，他们创建了两个微服务：用户 API 和帐户 API。用户 API 将处理用户帐户、API 密钥和身份验证，而帐户 API 将处理所有与计费相关的逻辑。一个非常符合逻辑的分离--但没过多久，他们发现了一个问题。 + +McFadden 解释说，“我们有一个名为 ”用户 API “的服务，还有一个名为”帐户 API “的服务。问题是，他们之间实际上有几个来回的电话。因此， 您会在帐户中执行一些操作，并在用户中具有调用和终结点，反之亦然” + +这两个服务的耦合太紧密了。 + +在设计微服务时， 如果您有多个服务引用同一个表， 则它是一个危险的信号，因为这可能意味着您的数据库是耦合的源头。 + +这确实是关于服务与数据的关系， 这正是Oleksiy Kovrin，[Swiftype SRE， Elastic][6] 的领导者， 告诉我。“我们在开发新服务时使用的主要基本原则之一是， 它们不应跨越数据库边界。每个服务都应依赖于自己的一组基础数据存储。这使我们能够集中访问控制、审计日志记录、缓存逻辑等。” + +Kovrin 接着解释说，如果数据库表的子集 “与数据集的其余部分没有或很少连接，则这是一个强烈的信号， 表明组件可以被隔离到单独的 API 或单独的服务中”。 + +Darby Frey ， [Lead Honestly][7] 的联合创始人，与此的观点相呼应：”每个服务都应该有自己的表 [并且] 永远不应该共享数据库表。“ + +#### #2: 数据库表数量最小化 + +微服务的理想尺寸足够小，但不会更小。每个服务的数据库表的数量也是如此。 + +Steven Czerwinski，[Scaylr][8] 的工程主管， 在接受采访时解释说 Scaylr 的最佳选择是 ”一个或两个服务的数据库表“。 + +SparkPost's Chris McFadden 同意：”我们有一个（suppression）限制微服务，它处理， 跟踪， 数以百万计和数十亿的条目周围的限制，但它都非常集中只是围绕限制，所以实际上只有一个或两个表。其他服务也是如此，比如 *webhooks* 。 + +#### #3: 考虑有状态和无状态 + +在设计微服务时，您需要问问自己它是否需要访问数据库，或者它是否会是处理 TB 级数据 (如电子邮件或日志) 的无状态服务。 + +Julien Lemoine， [Algolia][9] 的 CTO，解释说:：“我们通过定义服务的输入和输出来定义服务的边界。有时服务是网络 API ，但它也可能是在数据库中使用文件和生成记录的进程 (这就是我们的日志处理服务)。 + +事先要清楚状态，这将引导一个更好的服务设计。 + +#### #4: 考虑数据可用性需求 + +在设计微服务时，请记住哪些服务将依赖于此新服务， 以及在该数据不可用时的全系统影响。考虑到这一点，您可以正确地设计此服务的数据备份和恢复系统。 + +Steven Czerwinski 在 Scaylr 提到，由于关键客户行空间映射数据的重要性，它将以不同的方式复制和分离。 + +他补充说，”每个分片信息，在自己的小分区里。如果因为这部分客户群体不会有他们的可用日志而下降，那很糟糕，但它只影响5% 的客户，而不是100% 的客户。 + +#### #5: 真理的唯一来源 + +设计服务，使其成为系统中某些内容的唯一实际来源 + +例如，当您从电子商务网站订购内容时， 则会生成订单 ID ，其他服务可以使用此订单 ID 来查询订单服务，以获取有关订单的完整信息。使用 [publish/subscribe pattern][10] ，在服务之间传递的数据应该是订单 ID ， 而不是订单本身的属性信息。只有订单服务具有完整的信息，并且是给定订单的唯一实际来源。 + +### 大型团队的注意事项 + +考虑到上面列出的五个注意事项，较大的团队应了解其组织结构对微服务边界的影响。 + +对于大型组织，整个团队可以专门拥有服务，在确定服务边界时， 有组织性的考虑因素就会发挥作用。还有两个需要考虑的因素: **独立的发布计划**和**不同的正常运行时间**的重要性。 + +Khash Sajadi ， [Cloud66.][11] 的 CEO 说：”我们所看到的微服务最成功的实现要么基于软件设计原则 (例如域驱动设计和面向服务的体系结构)， 要么基于反映组织方法的设计原则“ + +”所以 (对于) 支付团队“ Sajadi 继续说，，”他们有支付服务或信用卡验证服务， 这就是他们向外界提供的服务。所以这不一定是关于软件的。这主要是关于为外界提供更多服务的业务单位 “ + +### 双披萨原理 + +Amazon 是一个拥有多个团队的大型组织的完美示例。正如在一篇文章中所提到的， [API Evangelist][12] ，Jeff Bezos向所有员工发出授权，告知他们公司内的每个团队都必须通过 API 进行沟通。任何没有被解雇的人都会被解雇。 + +这样，所有数据和功能都通过接口公开。Bezos 还设法让每个团队分离，定义他们的资源是什么， 并通过 API 使它们可用。亚马逊正在从地面上建立一个系统。这使得公司内的每一支团队都能成为彼此的合作伙伴。 + +Travis Reeder ， [Iron.io][13] 的CTO，谈论关于 Bezos 的内部提议。 + +”Jeff Bezos 规定所有团队都必须构建 API 才能与其他团队进行沟通，“ Reeder 说。”他也是提出‘双披萨’规则的人：一支球队不应该比两个比萨饼能养活的大。 + +“我认为这里也可以适用同样的方法：无论一个小型团队是否能够开发、管理和富有成效。如果它开始变得笨重或开始后退。可能会变得太大” Reeder 告诉我。 + +### 最后注意事项: 您的服务是否具有正确的大小和正确定义？ + +在微服务系统的测试和实施阶段，有一些指标需要记住。 + +#### 指标 #1: 服务之间是否存在过度依赖？ + +如果两个服务不断地相互回调，那么这就是耦合的强烈信号，也是它们可能更好地合并为一个服务的信号。 + +回到 Chris McFadden 的例子， 他有两个 API 服务、帐户和用户不断地相互通信， McFadden 提出了一个合并服务的想法， 并决定将其称为 “原告 API”。事实证明， 这是一项富有成效的战略。”我们开始做的是消除这些链接 [这是] 内部 API 调用投注他们之间“ McFadden 告诉我。这有助于简化代码。 + +#### 指标 #2: 设置服务的开销是否超过了服务独立的好处？ + +Darby Frey 解释说，“每个应用都需要将其日志聚合到某个位置，并需要进行监视。你需要设置它的警报。你需要有标准的作业程序，并在事情发生时运行书籍。您必须管理 SSH 对该事物的访问。为了让一个应用单纯运行， 必须存在一个巨大的基础。 + +### 主要外包 + +设计微服务往往会让人感觉更像是一门艺术， 而不是一门科学。对工程师来说， 这可能不是很好。外面有很多一般性的建议， 但有时可能有点太抽象了。让我们回顾一下在设计下一组微服务时要注意的五个具体特征： + + 1. 不与其他服务共享数据库表 + 2. 数据库表数量最小化 + 3. 考虑有状态和无状态 + 4. 考虑数据可用性需求 + 5. 真理的唯一来源 + + + +下次设计一组微服务并确定服务边界时，回顾这些原则应该会使任务变得更容易。 + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/18/4/guide-design-microservices + +作者：[Jake Lumetta][a] +选题：[lujun9972](https://github.com/lujun9972) +译者：[lixinyuxx](https://github.com/lixinyuxx) +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/jakelumetta +[1]:https://buttercms.com/books/microservices-for-startups/ +[2]:https://buttercms.com/books/microservices-for-startups/should-you-always-start-with-a-monolith +[3]:https://www.sparkpost.com/ +[4]:https://thebojan.ninja/2015/04/08/high-cohesion-loose-coupling/ +[5]:https://en.wikipedia.org/wiki/Single_responsibility_principle +[6]:https://www.elastic.co/solutions/site-search +[7]:https://leadhonestly.com/ +[8]:https://www.scalyr.com/ +[9]:https://www.algolia.com/ +[10]:https://en.wikipedia.org/wiki/Publish%E2%80%93subscribe_pattern +[11]:https://www.cloud66.com/ +[12]:https://apievangelist.com/2012/01/12/the-secret-to-amazons-success-internal-apis/ +[13]:https://www.iron.io/ diff --git a/translated/tech/20120201 Computer Laboratory - Raspberry Pi- Lesson 1 OK01.md b/translated/tech/20120201 Computer Laboratory - Raspberry Pi- Lesson 1 OK01.md new file mode 100644 index 0000000000..43c76fa0c5 --- /dev/null +++ b/translated/tech/20120201 Computer Laboratory - Raspberry Pi- Lesson 1 OK01.md @@ -0,0 +1,233 @@ +[#]: collector: (lujun9972) +[#]: translator: (qhwdw) +[#]: reviewer: (wxy) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Computer Laboratory – Raspberry Pi: Lesson 1 OK01) +[#]: via: (https://www.cl.cam.ac.uk/projects/raspberrypi/tutorials/os/ok01.html) +[#]: author: (Robert Mullins http://www.cl.cam.ac.uk/~rdm34) + +计算机实验室之树莓派：课程 1 OK01 +====== + +OK01 课程讲解了树莓派如何入门，以及在树莓派上如何启用靠近 RCA 和 USB 端口的 OK 或 ACT 的 LED 指示灯。这个指示灯最初是为了指示 OK 状态的，但它在第二版的树莓派上被改名为 ACT。 + +### 1、入门 + +我们假设你已经访问了[下载][1]页面，并且已经获得了必需的 GNU 工具链。也下载了一个称为操作系统模板的文件。请下载这个文件并在一个新目录中解开它。 + +### 2、开始 + +现在，你已经展开了这个模板文件，在 `source` 目录中创建一个名为 `main.s` 的文件。这个文件包含了这个操作系统的代码。具体来看，这个文件夹的结构应该像下面这样： + +``` +build/ + (empty) +source/ + main.s +kernel.ld +LICENSE +Makefile +``` + +用文本编辑器打开 `main.s` 文件，这样我们就可以输入汇编代码了。树莓派使用了称为 ARMv6 的汇编代码变体，这就是我们即将要写的汇编代码类型。 + +> 扩展名为 `.s` 的文件一般是汇编代码，需要记住的是，在这里它是 ARMv6 的汇编代码。 + +首先，我们复制下面的这些命令。 + +``` +.section .init +.globl _start +_start: +``` + +实际上，上面这些指令并没有在树莓派上做任何事情，它们是提供给汇编器的指令。汇编器是一个转换程序，它将我们能够理解的汇编代码转换成树莓派能够理解的机器代码。在汇编代码中，每个行都是一个新的命令。上面的第一行告诉汇编器 [^1] 在哪里放我们的代码。我们提供的模板中将它放到一个名为 `.init` 的节中的原因是，它是输出的起始点。这很重要，因为我们希望确保我们能够控制哪个代码首先运行。如果不这样做，首先运行的代码将是按字母顺序排在前面的代码！`.section` 命令简单地告诉汇编器，哪个节中放置代码，从这个点开始，直到下一个 `.section` 或文件结束为止。 + +``` +在汇编代码中，你可以跳行、在命令前或后放置空格去提升可读性。 +``` + +接下来两行是停止一个警告消息，它们并不重要。[^2] + +### 3、第一行代码 + +现在，我们正式开始写代码。计算机执行汇编代码时，是简单地一行一行按顺序执行每个指令，除非明确告诉它不这样做。每个指令都是开始于一个新行。 + +复制下列指令。 + +``` +ldr r0,=0x20200000 +``` + +> `ldr reg,=val` 将数字 `val` 加载到名为 `reg` 的寄存器中。 + +那是我们的第一个命令。它告诉处理器将数字 `0x20200000` 保存到寄存器 `r0` 中。在这里我需要去回答两个问题，寄存器register是什么？`0x20200000` 是一个什么样的数字？ + +寄存器在处理器中就是一个极小的内存块，它是处理器保存正在处理的数字的地方。处理器中有很多寄存器，很多都有专门的用途，我们在后面会一一接触到它们。最重要的有十三个（命名为 `r0`、`r1`、`r2`、…、`r9`、`r10`、`r11`、`r12`），它们被称为通用寄存器，你可以使用它们做任何计算。由于是写我们的第一行代码，我们在示例中使用了 `r0`，当然你可以使用它们中的任何一个。只要后面始终如一就没有问题。 + +> 树莓派上的一个单独的寄存器能够保存任何介于 `0` 到 `4,294,967,295`（含）之间的任意整数，它可能看起来像一个很大的内存，实际上它仅有 32 个二进制比特。 + +`0x20200000` 确实是一个数字。只不过它是以十六进制表示的。下面的内容详细解释了十六进制的相关信息： + +> 延伸阅读：十六进制解释 + +> 十六进制是另一种表示数字的方式。你或许只知道十进制的数字表示方法，十进制共有十个数字：`0`、`1`、`2`、`3`、`4`、`5`、`6`、`7`、`8` 和 `9`。十六进制共有十六个数字：`0`、`1`、`2`、`3`、`4`、`5`、`6`、`7`、`8`、`9`、`a`、`b`、`c`、`d`、`e` 和 `f`。 + +> 你可能还记得十进制是如何用位制来表示的。即最右侧的数字是个位，紧接着的左边一位是十位，再接着的左边一位是百位，依此类推。也就是说，它的值是 100 × 百位的数字，再加上 10 × 十位的数字，再加上 1 × 个位的数字。 + +> ![567 is 5 hundreds, 6 tens and 7 units.][2] + +> 从数学的角度来看，我们可以发现规律，最右侧的数字是 100 = 1s，紧接着的左边一位是 101 = 10s，再接着是 102 = 100s，依此类推。我们设定在系统中，0 是最低位，紧接着是 1，依此类推。但如果我们使用一个不同于 10 的数字为幂底会是什么样呢？我们在系统中使用的十六进制就是这样的一个数字。 + +> ![567 is 5x10^2+6x10^1+7x10^0][3] + +> ![567 = 5x10^2+6x10^1+7x10^0 = 2x16^2+3x16^1+7x16^0][4] + +> 上面的数学等式表明，十进制的数字 567 等于十六进制的数字 237。通常我们需要在系统中明确它们，我们使用下标 10 表示它是十进制数字，用下标 16 表示它是十六进制数字。由于在汇编代码中写上下标的小数字很困难，因此我们使用 0x 来表示它是一个十六进制的数字，因此 0x237 的意思就是 23716 。 + +> 那么，后面的 `a`、`b`、`c`、`d`、`e` 和 `f` 又是什么呢？好问题！在十六进制中为了能够写每个数字，我们就需要额外的东西。例如 916 = 9×160 = 910 ，但是 1016 = 1×161 + 1×160 = 1610 。因此，如果我们只使用 0、1、2、3、4、5、6、7、8 和 9，我们就无法写出 1010 、1110 、1210 、1310 、1410 、1510 。因此我们引入了 6 个新的数字，这样 a16 = 1010 、b16 = 1110 、c16 = 1210 、d16 = 1310 、e16 = 1410 、f16 = 1510 。 + +> 所以，我们就有了另一种写数字的方式。但是我们为什么要这么麻烦呢？好问题！由于计算机总是工作在二进制中，事实证明，十六进制是非常有用的，因为每个十六进制数字正好是四个二进制数字的长度。这种方法还有另外一个好处，那就是许多计算机的数字都是十六进制的整数倍，而不是十进制的整数倍。比如，我在上面的汇编代码中使用的一个数字 2020000016 。如果我们用十进制来写，它就是一个不太好记住的数字 53896806410 。 + +> 我们可以用下面的简单方法将十进制转换成十六进制： + +> ![Conversion example][5] + +> 1. 我们以十进制数字 567 为例来说明。 +> 2. 将十进制数字 567 除以 16 并计算其余数。例如 567 ÷ 16 = 35 余数为 7。 +> 3. 在十六进制中余数就是答案中的最后一位数字，在我们的例子中它是 7。 +> 4. 重复第 2 步和第 3 步，直到除法结果的整数部分为 0。例如 35 ÷ 16 = 2 余数为 3，因此 3 就是答案中的下一位。2 ÷ 16 = 0 余数为 2，因此 2 就是答案的接下来一位。 +> 5. 一旦除法结果的整数部分为 0 就结束了。答案就是反序的余数，因此 56710 = 23716。 + +> 转换十六进制数字为十进制，也很容易，将数字展开即可，因此 23716 = 2×162 + 3×161 +7 ×160 = 2×256 + 3×16 + 7×1 = 512 + 48 + 7 = 567。 + +因此，我们所写的第一个汇编命令是将数字 2020000016 加载到寄存器 `r0` 中。那个命令看起来似乎没有什么用，但事实并非如此。在计算机中，有大量的内存块和设备。为了能够访问它们，我们给每个内存块和设备指定了一个地址。就像邮政地址或网站地址一样，它用于标识我们想去访问的内存块或设备的位置。计算机中的地址就是一串数字，因此上面的数字 2020000016 就是 GPIO 控制器的地址。这个地址是由制造商的设计所决定的，他们也可以使用其它地址（只要不与其它的冲突即可）。我之所以知道这个地址是 GPIO 控制器的地址是因为我看了它的手册，[^3] 地址的使用没有专门的规范（除了它们都是以十六进制表示的大数以外）。 + +### 4、启用输出 + +![A diagram showing key parts of the GPIO controller.][6] + +阅读了手册可以得知，我们需要给 GPIO 控制器发送两个消息。我们必须用它的语言告诉它，如果我们这样做了，它将非常乐意实现我们的意图，去打开 OK 的 LED 指示灯。幸运的是，它是一个非常简单的芯片，为了让它能够理解我们要做什么，只需要给它设定几个数字即可。 + +``` +mov r1,#1 +lsl r1,#18 +str r1,[r0,#4] +``` + +> `mov reg,#val` 将数字 `val` 放到名为 `reg` 的寄存器中。 + +> `lsl reg,#val` 将寄存器 `reg` 中的二进制操作数左移 `val` 位。 + +> `str reg,[dest,#val]` 将寄存器 `reg` 中的数字保存到地址 `dest + val` 上。 + +这些命令的作用是在 GPIO 的第 16 号插针上启用输出。首先我们在寄存器 `r1` 中获取一个必需的值，接着将这个值发送到 GPIO 控制器。因此，前两个命令是尝试取值到寄存器 `r1` 中，我们可以像前面一样使用另一个命令 `ldr` 来实现，但 `lsl` 命令对我们后面能够设置任何给定的 GPIO 针比较有用，因此从一个公式中推导出值要比直接写入来好一些。表示 OK 的 LED 灯是直接连线到 GPIO 的第 16 号针脚上的，因此我们需要发送一个命令去启用第 16 号针脚。 + +寄存器 `r1` 中的值是启用 LED 针所需要的。第一行命令将数字 110 放到 `r1` 中。在这个操作中 `mov` 命令要比 `ldr` 命令快很多，因为它不需要与内存交互，而 `ldr` 命令是将需要的值从内存中加载到寄存器中。尽管如此，`mov` 命令仅能用于加载某些值。[^4] 在 ARM 汇编代码中，基本上每个指令都使用一个三字母代码表示。它们被称为助记词，用于表示操作的用途。`mov` 是 “move” 的简写，而 `ldr` 是 “load register” 的简写。`mov` 是将第二个参数 `#1` 移动到前面的 `r1` 寄存器中。一般情况下，`#` 肯定是表示一个数字，但我们已经看到了不符合这种情况的一个反例。 + +第二个指令是 `lsl`（逻辑左移）。它的意思是将第一个参数的二进制操作数向左移第二个参数所表示的位数。在这个案例中，将 110 （即 12 ）向左移 18 位（将它变成 10000000000000000002=26214410 ）。 + +如果你不熟悉二进制表示法，可以看下面的内容： + +> 延伸阅读： 二进制解释 + +> 与十六进制一样，二进制是写数字的另一种方法。在二进制中只有两个数字，即 `0` 和 `1`。它在计算机中非常有用，因为我们可以用电路来实现它，即电流能够通过电路表示为 `1`，而电流不能通过电路表示为 `0`。这就是计算机能够完成真实工作和做数学运算的原理。尽管二进制只有两个数字，但它却能够表示任何一个数字，只是写起来有点长而已。 + +> ![567 in decimal = 1000110111 in binary][7] + +> 这个图片展示了 56710 的二进制表示是 10001101112 。我们使用下标 2 来表示这个数字是用二进制写的。 + +> 我们在汇编代码中大量使用二进制的其中一个巧合之处是，数字可以很容易地被 `2` 的幂（即 `1`、`2`、`4`、`8`、`16`）乘或除。通常乘法和除法都是非常难的，而在某些特殊情况下却变得非常容易，所以二进制非常重要。 + +> ![13*4 = 52, 1101*100=110100][8] + +> 将一个二进制数字左移 `n` 位就相当于将这个数字乘以 2n。因此，如果我们想将一个数乘以 4，我们只需要将这个数字左移 2 位。如果我们想将它乘以 256，我们只需要将它左移 8 位。如果我们想将一个数乘以 12 这样的数字，我们可以有一个替代做法，就是先将这个数乘以 8，然后再将那个数乘以 4，最后将两次相乘的结果相加即可得到最终结果（N × 12 = N × (8 + 4) = N × 8 + N × 4）。 + +> ![53/16 = 3, 110100/10000=11][9] + +> 右移一个二进制数 `n` 位就相当于这个数除以 2n 。在右移操作中，除法的余数位将被丢弃。不幸的是，如果对一个不能被 2 的幂次方除尽的二进制数字做除法是非常难的，这将在 [课程 9 Screen04][10] 中讲到。 + +> ![Binary Terminology][11] + +> 这个图展示了二进制常用的术语。一个比特bit就是一个单独的二进制位。一个“半字节nibble“ 是 4 个二进制位。一个字节byte是 2 个半字节，也就是 8 个比特。半字half是指一个字长度的一半，这里是 2 个字节。字word是指处理器上寄存器的大小，因此，树莓派的字长是 4 字节。按惯例，将一个字最高有效位标识为 31，而将最低有效位标识为 0。顶部或最高位表示最高有效位，而底部或最低位表示最低有效位。一个 kilobyte（KB）就是 1000 字节，一个 megabyte 就是 1000 KB。这样表示会导致一些困惑，到底应该是 1000 还是 1024（二进制中的整数）。鉴于这种情况，新的国际标准规定，一个 KB 等于 1000 字节，而一个 Kibibyte（KiB）是 1024 字节。一个 Kb 是 1000 比特，而一个 Kib 是 1024 比特。 + +> 树莓派默认采用小端法，也就是说，从你刚才写的地址上加载一个字节时，是从一个字的低位字节开始加载的。 + +再强调一次，我们只有去阅读手册才能知道我们所需要的值。手册上说，GPIO 控制器中有一个 24 字节的集合，由它来决定 GPIO 针脚的设置。第一个 4 字节与前 10 个 GPIO 针脚有关，第二个 4 字节与接下来的 10 个针脚有关，依此类推。总共有 54 个 GPIO 针脚，因此，我们需要 6 个 4 字节的一个集合，总共是 24 个字节。在每个 4 字节中，每 3 个比特与一个特定的 GPIO 针脚有关。我们想去启用的是第 16 号 GPIO 针脚，因此我们需要去设置第二组 4 字节，因为第二组的 4 字节用于处理 GPIO 针脚的第 10-19 号，而我们需要第 6 组 3 比特，它在上面的代码中的编号是 18（6×3）。 + +最后的 `str`（“store register”）命令去保存第一个参数中的值，将寄存器 `r1` 中的值保存到后面的表达式计算出来的地址上。这个表达式可以是一个寄存器，在上面的例子中是 `r0`，我们知道 `r0` 中保存了 GPIO 控制器的地址，而另一个值是加到它上面的，在这个例子中是 `#4`。它的意思是将 GPIO 控制器地址加上 `4` 得到一个新的地址，并将寄存器 `r1` 中的值写到那个地址上。那个地址就是我们前面提到的第二组 4 字节的位置，因此，我们发送我们的第一个消息到 GPIO 控制器上，告诉它准备启用 GPIO 第 16 号针脚的输出。 + +### 5、生命的信号 + +现在，LED 已经做好了打开准备，我们还需要实际去打开它。意味着需要给 GPIO 控制器发送一个消息去关闭 16 号针脚。是的，你没有看错，就是要发送一个关闭的消息。芯片制造商认为，在 GPIO 针脚关闭时打开 LED 更有意义。[^5] 硬件工程师经常做这种反常理的决策，似乎是为了让操作系统开发者保持警觉。可以认为是给自己的一个警告。 + +``` +mov r1,#1 +lsl r1,#16 +str r1,[r0,#40] +``` + +希望你能够认识上面全部的命令，先不要管它的值。第一个命令和前面一样，是将值 `1` 推入到寄存器 `r1` 中。第二个命令是将二进制的 `1` 左移 16 位。由于我们是希望关闭 GPIO 的 16 号针脚，我们需要在下一个消息中将第 16 比特设置为 1（想设置其它针脚只需要改变相应的比特位即可）。最后，我们写这个值到 GPIO 控制器地址加上 4010 的地址上，这将使那个针脚关闭（加上 28 将打开针脚）。 + +### 6、永远幸福快乐 + +似乎我们现在就可以结束了，但不幸的是，处理器并不知道我们做了什么。事实上，处理器只要通电，它就永不停止地运转。因此，我们需要给它一个任务，让它一直运转下去，否则，树莓派将进入休眠（本示例中不会，LED 灯会一直亮着）。 + +``` +loop$: +b loop$ + +``` + +> `name:` 下一行的名字。 + +> `b label` 下一行将去标签 `label` 处运行。 + +第一行不是一个命令，而是一个标签。它给下一行命名为 `loop$`，这意味着我们能够通过名字来指向到该行。这就称为一个标签。当代码被转换成二进制后，标签将被丢弃，但这对我们通过名字而不是数字（地址）找到行比较有用。按惯例，我们使用一个 `​$` 表示这个标签只对这个代码块中的代码起作用，让其它人知道，它不对整个程序起作用。`b`（“branch”）命令将去运行指定的标签中的命令，而不是去运行它后面的下一个命令。因此，下一行将再次去运行这个 `b` 命令，这将导致永远循环下去。因此处理器将进入一个无限循环中，直到它安全关闭为止。 + +代码块结尾的一个空行是有意这样写的。GNU 工具链要求所有的汇编代码文件都是以空行结束的，因此，这就可以你确实是要结束了，并且文件没有被截断。如果你不这样处理，在汇编器运行时，你将收到烦人的警告。 + +### 7、树莓派上场 + +由于我们已经写完了代码，现在，我们可以将它上传到树莓派中了。在你的计算机上打开一个终端，改变当前工作目录为 `source` 文件夹的父级目录。输入 `make` 然后回车。如果报错，请参考排错章节。如果没有报错，你将生成三个文件。 `kernel.img` 是你的编译后的操作系统镜像。`kernel.list` 是你写的汇编代码的一个清单，它实际上是生成的。这在将来检查程序是否正确时非常有用。`kernel.map` 文件包含所有标签结束位置的一个映射，这对于跟踪值非常有用。 + +为安装你的操作系统，需要先有一个已经安装了树莓派操作系统的 SD 卡。如果你浏览 SD 卡中的文件，你应该能看到一个名为 `kernel.img` 的文件。将这个文件重命名为其它名字，比如 `kernel_linux.img`。然后，复制你编译的 `kernel.img` 文件到 SD 卡中原来的位置，这将用你的操作系统镜像文件替换现在的树莓派操作系统镜像。想切换回来时，只需要简单地删除你自己的 `kernel.img` 文件，然后将前面重命名的文件改回 `kernel.img` 即可。我发现，保留一个原始的树莓派操作系统的备份是非常有用的，万一你要用到它呢。 + +将这个 SD 卡插入到树莓派，并打开它的电源。这个 OK 的 LED 灯将亮起来。如果不是这样，请查看故障排除页面。如果一切如愿，恭喜你，你已经写出了你的第一个操作系统。[课程 2 OK02][12] 将指导你让 LED 灯闪烁和关闭闪烁。 + +[^1]: OK, I'm lying it tells the linker, which is another program used to link several assembled files together. It doesn't really matter. +[^2]: Clearly they're important to you. Since the GNU toolchain is mainly used for creating programs, it expects there to be an entry point labelled `_start`. As we're making an operating system, the `_start` is always whatever comes first, which we set up with the `.section .init` command. However, if we don't say where the entry point is, the toolchain gets upset. Thus, the first line says that we are going to define a symbol called `_start` for all to see (globally), and the second line says to make the symbol `_start` the address of the next line. We will come onto addresses shortly. +[^3]: This tutorial is designed to spare you the pain of reading it, but, if you must, it can be found here [SoC-Peripherals.pdf](https://www.cl.cam.ac.uk/projects/raspberrypi/tutorials/os/downloads/SoC-Peripherals.pdf). For added confusion, the manual uses a different addressing system. An address listed as 0x7E200000 would be 0x20200000 in our OS. +[^4]: Only values which have a binary representation which only has 1s in the first 8 bits of the representation. In other words, 8 1s or 0s followed by only 0s. +[^5]: A hardware engineer was kind enough to explain this to me as follows: + + The reason is that modern chips are made of a technology called CMOS, which stands for Complementary Metal Oxide Semiconductor. The Complementary part means each signal is connected to two transistors, one made of material called N-type semiconductor which is used to pull it to a low voltage and another made of P-type material to pull it to a high voltage. Only one transistor of the pair turns on at any time, otherwise we'd get a short circuit. P-type isn't as conductive as N-type, which means the P-type transistor has to be about 3 times as big to provide the same current. This is why LEDs are often wired to turn on by pulling them low, because the N-type is stronger at pulling low than the P-type is in pulling high. + + There's another reason. Back in the 1970s chips were made out of entirely out of N-type material ('NMOS'), with the P-type replaced by a resistor. That means that when a signal is pulled low the chip is consuming power (and getting hot) even while it isn't doing anything. Your phone getting hot and flattening the battery when it's in your pocket doing nothing wouldn't be good. So signals were designed to be 'active low' so that they're high when inactive and so don't take any power. Even though we don't use NMOS any more, it's still often quicker to pull a signal low with the N-type than to pull it high with the P-type. Often a signal that's 'active low' is marked with a bar over the top of the name, or written as SIGNAL_n or /SIGNAL. But it can still be confusing, even for hardware engineers! + +-------------------------------------------------------------------------------- + +via: https://www.cl.cam.ac.uk/projects/raspberrypi/tutorials/os/ok01.html + +作者：[Robert Mullins][a] +选题：[lujun9972][b] +译者：[qhwdw](https://github.com/qhwdw) +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]: http://www.cl.cam.ac.uk/~rdm34 +[b]: https://github.com/lujun9972 +[1]: https://www.cl.cam.ac.uk/projects/raspberrypi/tutorials/os/downloads.html +[2]: https://www.cl.cam.ac.uk/projects/raspberrypi/tutorials/os/images/hexadecimal1.png +[3]: https://www.cl.cam.ac.uk/projects/raspberrypi/tutorials/os/images/hexadecimal2.png +[4]: https://www.cl.cam.ac.uk/projects/raspberrypi/tutorials/os/images/hexadecimal3.png +[5]: https://www.cl.cam.ac.uk/projects/raspberrypi/tutorials/os/images/hexadecimal4.png +[6]: https://www.cl.cam.ac.uk/projects/raspberrypi/tutorials/os/images/gpioController.png +[7]: https://www.cl.cam.ac.uk/projects/raspberrypi/tutorials/os/images/binary1.png +[8]: https://www.cl.cam.ac.uk/projects/raspberrypi/tutorials/os/images/binary2.png +[9]: https://www.cl.cam.ac.uk/projects/raspberrypi/tutorials/os/images/binary3.png +[10]: https://www.cl.cam.ac.uk/projects/raspberrypi/tutorials/os/screen04.html +[11]: https://www.cl.cam.ac.uk/projects/raspberrypi/tutorials/os/images/binary4.png +[12]: https://www.cl.cam.ac.uk/projects/raspberrypi/tutorials/os/ok02.html diff --git a/translated/tech/20180326 Manage your workstation with Ansible- Automating configuration.md b/translated/tech/20180326 Manage your workstation with Ansible- Automating configuration.md deleted file mode 100644 index c464f4ea32..0000000000 --- a/translated/tech/20180326 Manage your workstation with Ansible- Automating configuration.md +++ /dev/null @@ -1,231 +0,0 @@ -使用Ansible来管理你的工作站：配置自动化 -====== - -![](https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/robot_arm_artificial_ai.png?itok=8CUU3U_7) - -Ansible是一个令人惊讶的自动化的配置管理工具。主要应用在服务器和云部署上，但在工作站上的应用（无论是台式机还是笔记本）却得到了很少的关注，这就是本系列所要关注的。 - -在这个系列的第一部分，我会向你展示'ansible-pull'命令的基本用法，我们创建了一个安装了少量包的palybook.它本身是没有多大的用处的，但是它为后续的自动化做了准备。 - -在这篇文章中，所有的事件操作都是闭环的，而且在最后部分，我们将会有一个针对工作站自动配置的完整的工作解决方案。现在，我们将要设置Ansible的配置，这样未来将要做的改变将会自动的部署应用到我们的工作站上。现阶段，假设你已经完成了第一部分的工作。如果没有的话，当你完成的时候回到本文。你应该已经有一个包含第一篇文章中代码的Github库。我们将直接按照之前的方式创建。 - -首先，因为我们要做的不仅仅是安装包文件，所以我们要做一些重新的组织工作。现在，我们已经有一个名为'local.yml'并包含以下内容的playbook: -``` -- hosts: localhost - - become: true - - tasks: - - - name: Install packages - - apt: name={{item}} - - with_items: - - - htop - - - mc - - - tmux - -``` - -如果我们仅仅想实现一个任务那么上面的配置就足够了。随着向我们的配置中不断的添加内容，这个文件将会变的相当的庞大和杂乱。最好能够根据不同类型的配置将play文件分为独立的文件。为了达到这个要求，创建一个名为taskbook的文件，它和playbook很像但内容更加的流线型。让我们在Git库中为taskbook创建一个目录。 -``` -mkdir tasks - -``` - -在'local.yml'playbook中的代码使它很好过过渡到成为安装包文件的taskbook.让我们把这个文件移动到刚刚创建好并新命名的目录中。 - -``` -mv local.yml tasks/packages.yml - -``` -现在，我们编辑'packages.yml'文件将它进行大幅的瘦身，事实上，我们可以精简除了独立任务本身之外的所有内容。让我们把'packages.yml'编辑成如下的形式： -``` -- name: Install packages - - apt: name={{item}} - - with_items: - - - htop - - - mc - - - tmux - -``` - -正如你所看到的，它使用同样的语法，但我们去掉了对这个任务无用没有必要的所有内容。现在我们有了一个专门安装包文件的taskbook.然而我们仍然需要一个名为'local.yml'的文件，因为执行'ansible-pull'命令时仍然会去发现这个文件。所以我们将在我们库的根目录下（不是在'task'目录下）创建一个包含这些内容的全新文件： -``` -- hosts: localhost - - become: true - - pre_tasks: - - - name: update repositories - - apt: update_cache=yes - - changed_when: False - - - - tasks: - - - include: tasks/packages.yml - -``` - -这个新的'local.yml'扮演的是将要导入我们的taksbooks的主页的角色。我已经在这个文件中添加了一些你在这个系列中看不到的内容。首先，在这个文件的开头处，我添加了'pre——tasks',这个任务的作用是在其他所有任务运行之前先运行某个任务。在这种情况下，我们给Ansible的命令是让它去更新我们的分布存储库主页，下面的配置将执行这个任务要求： - -``` -apt: update_cache=yes - -``` -通常'apt'模块是用来安装包文件的，但我们也能够让它来更新库索引。这样做的目的是让我们的每个play在Ansible运行的时候能够以最新的索引工作。这将确保我们在使用一个老旧的索引安装一个包的时候不会出现问题。因为'apt'模块仅仅在Debian，Ubuntu和他们的衍生环境下工作。如果你运行的一个不同的环境，你期望在你的环境中使用一个特殊的模块而不是'apt'。如果你需要使用一个不同的模块请查看Ansible的相关文档。 - -下面这行值得以后解释： -``` -changed_when: False - -``` -在独立任务中的这行阻止了Ansible去报告play改变的结果即使是它本身在系统中导致的一个改变。在这中情况下，我们不会去在意库索引是否包含新的数据；它几乎总是会的，因为库总是在改变的。我们不会去在意'apt'库的改变，因为索引的改变是正常的过程。如果我们删除这行，我们将在过程保告的后面看到所有的变动，即使仅仅库的更新而已。最好能够去忽略这类的改变。 - -接下来是常规任务的阶段，我们将创建好的taskbook导入。我们每次添加另一个taskbook的时候，要添加下面这一行： -``` -tasks: - - - include: tasks/packages.yml - -``` - -如果你将要运行'ansible-pull'命令，他应该向上一篇文章中的那样做同样重要的事情。 不同的是我们已经提高了我们的组织并且能够更有效的扩展它。'ansible-pull'命令的语法，为了节省你到上一篇文章中去寻找，参考如下： -``` -sudo ansible-pull -U https://github.com//ansible.git - -``` -如果你还记得话，'ansible-pull'的命令拉取一个Git库并且应用了它所包含的配置。 - -既然我们的基础已经搭建好，我们现在可以扩展我们的Ansible并且添加功能。更特别的是，我们将添加配置来自动化的部署对工作站要做的改变。为了支撑这个要求，首先我们要创建一个特殊的账户来应用我们的Ansible配置。这个不是必要的，我们仍然能够在我们自己的用户下运行Ansible配置。但是使用一个隔离的用户能够将其隔离到不需要我们参与的在后台运行的一个系统进程中， - -我们可以使用常规的方式来创建这个用户，但是既然我们正在使用Ansible,我们应该尽量避开使用手动的改变。替代的是，我们将会创建一个taskbook来处理用户的创建任务。这个taskbook目前将会仅仅创建一个用户，但你可以在这个taskbook中添加额外的plays来创建更多的用户。我将这个用户命名为'ansible'，你可以按照自己的想法来命名（如果你做了这个改变要确保更新所有的变动）。让我们来创建一个名为'user.yml'的taskbook并且将以下代码写进去： - -``` -- name: create ansible user - - user: name=ansible uid=900 - -``` -下一步，我们需要编辑'local.yml'文件，将这个新的taskbook添加进去，像如下这样写： - -``` -- hosts: localhost - - become: true - - pre_tasks: - - - name: update repositories - - apt: update_cache=yes - - changed_when: False - - - - tasks: - - - include: tasks/users.yml - - - include: tasks/packages.yml - -``` -现在当我们运行'ansible-pull'命令的时候，一个名为'ansible'的用户将会在系统中被创建。注意我特地通过参数'UID'为这个用户声明了用户ID为900。这个不是必须的，但建议直接创建好UID。因为在1000以下的UID在登陆界面是不会显示的，这样是很棒的因为我们根本没有需要去使用'ansibe'账户来登陆我们的桌面。UID 900是固定的；它应该是在1000以下没有被使用的任何一个数值。你可以使用以下命令在系统中去验证UID 900是否已经被使用了： - -``` -cat /etc/passwd |grep 900 - -``` -然而，你使用这个UID应该不会遇到什么问题，因为迄今为止在我使用的任何发行版中我还没遇到过它是被默认使用的。 - -现在，我们已经拥有了一个名为'ansible'的账户，它将会在之后的自动化配置中使用。接下来，我们可以创建实际的定时作业来自动操作它。而不是将其放置到我们刚刚创建的'users.yml'文件中，我们应该将其分开放到它自己的文件中。在任务目录中创建一个名为'cron.yml'的taskbook并且将以下的代买写进去： -``` -- name: install cron job (ansible-pull) - - cron: user="ansible" name="ansible provision" minute="*/10" job="/usr/bin/ansible-pull -o -U https://github.com//ansible.git > /dev/null" - -``` -定时模块的语法几乎是不需加以说明的。通过这个play,我们创建了一个通过用户'ansible'运行的定时作业。这个作业将每隔10分钟执行一次，下面是它将要执行的命令： - -``` -/usr/bin/ansible-pull -o -U https://github.com//ansible.git > /dev/null - -``` -同样，我们也可以添加想要我们的所有工作站部署的额外定时作业到这个文件中。我们只需要在新的定时作业中添加额外的palys即可。然而，仅仅是添加一个定时的taskbook是不够的，我们还需要将它添加到'local.yml'文件中以便它能够被调用。将下面的一行添加到末尾： -``` -- include: tasks/cron.yml - -``` -现在当'ansible-pull'命令执行的时候，它将会以通过用户'ansible'每个十分钟设置一个新的定时作业。但是，每个十分钟运行一个Ansible作业并不是一个好的方式因为这个将消耗很多的CPU资源。每隔十分钟来运行对于Ansible来说是毫无意义的除非欧文已经在Git库中改变一些东西。 - -然而，我们已经解决了这个问题。注意到我在定时作业中的命令'ansible-pill'添加的我们之前从未用到过的参数'-o'.这个参数告诉Ansible只有在从上次'ansible-pull'被调用以后库有了变化后才会运行。如果库没有任何变化，他将不会做任何事情。通过这个方法，你将不会无端的浪费CPU资源。当然，一些CPU资源将会在下来存储库的时候被使用，但不会像再一次应用整个配置的时候使用的那么多。当'ansible-pull'执行的时候，它将会遍历在playbooks和taskbooks中的所有任务，但至少它不会毫无目的的运行。 - -尽管我们已经添加了所有必须的配置要素来自动化'ansible-pull',它任然还不能正常的工作。'ansible-pull'命令需要sudo的权限来运行，这将允许它执行系统级的命令。然而我们创建的用户'ansible'并没有被设置为以'sudo'的权限来执行命令，因此当定时作业触发的时候，执行将会失败。通常沃恩可以使用命令'visudo'来手动的去设置用户'ansible'的拥有这个权限。然而我们现在应该以Ansible的方式来操作，而且这将会是一个向你展示'copy'模块是如何工作的机会。'copy'模块允许你从库复制一个文件到文件系统的任何位置。在这个案列中，我们将会复制'sudo'的一个配置文件到'/etc/sudoers.d/'以便用户'ansible'能够以管理员的权限执行任务。 - -打开'users.yml',将下面的play添加到文件末尾。 - -``` -- name: copy sudoers_ansible - - copy: src=files/sudoers_ansible dest=/etc/sudoers.d/ansible owner=root group=root mode=0440 - -``` -'copy'模块，正如我们看到的，从库复制一个文件到其他任何位置。在这个过程中，我们正在抓取一个名为'sudoers_ansible'(我们将在后续创建)的文件并将它复制到拥有者为'root'的'/etc/sudoers/ansible'中。 - -接下来，我们需要创建我们将要复制的文件。在你的库的根目录下，创建一个名为'files'的目录： - -``` -mkdir files - -``` -然后，在我们刚刚创建的'files'目录里，创建包含以下内容的名为'sudoers_ansible'的文件： -``` -ansible ALL=(ALL) NOPASSWD: ALL - -``` -在'/etc/sudoer.d'目录里创建一个文件，就像我们正在这样做的，允许我们为一个特殊的用户配置'sudo'权限。现在我们正在通过'sudo'允许用户'ansible'不需要密码拥有完全控制权限。这将允许'ansible-pull'以后台任务的形式运行而不需要手动去运行。 - -现在，你可以通过再次运行'ansible-pull'来拉取最新的变动： -``` -sudo ansible-pull -U https://github.com//ansible.git - -``` -从这个节点开始，'ansible-pull'的定时作业将会在后台每隔十分钟运行一次来检查你的库是否有变化，如果它发现有变化，将会运行你的palybook并且应用你的taskbooks. - -所以现在我们有了一个完整的工作方案。当你第一次设置一台新的笔记本或者台式机的时候，你要去手动的运行'ansible-pull'命令，但仅仅是在第一次的时候。从第一次之后，用户'ansible'将会在后台接手后续的运行任务。当你想对你的机器做变动的时候，你只需要简单的去拉取你的Git库来做变动，然后将这些变化回传到库中。接着，当定时作业下次在每台机器上运行的时候，它将会拉取变动的部分并应用它们。你现在只需要做一次变动，你的所有工作站将会跟着一起变动。这方法尽管有一点不方便，通常，你会有一个你的机器列表的文件和包含不同机器的规则。不管怎样，'ansible-pull'的方法，就像在文章中描述的，是管理工作站配置的非常有效的方法。 - -我已经在我的[Github repository]中更新了这篇文章中的代码，所以你可以随时去浏览来再一次检查你的语法。同时我将前一篇文章中的代码移到了它自己的目录中。 - -在第三部分，我们将通过介绍使用Ansible来配置GNOME桌面设置来结束这个系列。我将会告诉你如何设置你的墙纸和锁屏壁纸，应用一个桌面主题以及更多的东西。 - -同时，到了布置一些作业的时候了，大多数人有我们使用的各种应用的配置文件。可能是Bash,Vim或者其他你使用的工具的配置文件。现在你可以尝试通过我们在使用的Ansible库来自动复制这些配置到你的机器中。在这篇文章中，我已将想你展示了如何去复制文件，所以去尝试以下看看你是都已经能应用这些知识。 - --------------------------------------------------------------------------------- - -via: https://opensource.com/article/18/3/manage-your-workstation-configuration-ansible-part-2 - -作者：[Jay LaCroix][a] -译者：[FelixYFZ](https://github.com/FelixYFZ) -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://opensource.com/users/jlacroix -[1]:https://opensource.com/article/18/3/manage-workstation-ansible -[2]:https://github.com/jlacroix82/ansible_article.git diff --git a/translated/tech/20180503 11 Methods To Find System-Server Uptime In Linux.md b/translated/tech/20180503 11 Methods To Find System-Server Uptime In Linux.md deleted file mode 100644 index 68ca8a1371..0000000000 --- a/translated/tech/20180503 11 Methods To Find System-Server Uptime In Linux.md +++ /dev/null @@ -1,200 +0,0 @@ -Linux 上查看系统/服务器运行时间的 11 种方法 -====== -你是否想知道自己的 Linux 系统除宕机外正常运行了多长时间？系统什么时候启动以及现在的日期？ - -Linux 上有多个查看服务器/系统运行时间的命令，大多数用户喜欢使用标准并且很有名的 `uptime` 命令获取这些具体的信息。 - -服务器的运行时间对一些用户来说不那么重要，但是当服务器运行诸如在线商城门户portal、网上银行门户等关键任务应用mission-critical applications时，它对于服务器管理员server adminstrators来说就至关重要。 - -它必须做到 0 宕机，因为一旦停机就会影响到数百万用户。 - -正如我所说，许多命令都可以让用户看到 Linux 服务器的运行时间。在这篇教程里我会教你如何使用下面 11 种方式来查看。 - -正常运行时间uptime指的是服务器自从上次关闭或重启以来经过的时间。 - -`uptime` 命令获取 `/proc` 文件中的详细信息并输出正常运行时间，`/proc` 文件不能直接读取。 - -以下这些命令会输出系统运行和启动的时间。也会显示一些额外的信息。 - -### 方法 1：使用 uptime 命令 - -`uptime` 命令会告诉你系统运行了多长时间。它会用一行显示以下信息。 - -当前时间，系统运行时间，当前登录用户的数量，过去 1 分钟、5 分钟、15 分钟系统负载的均值。 - -``` -# uptime - - 08:34:29 up 21 days, 5:46, 1 user, load average: 0.06, 0.04, 0.00 - -``` - -### 方法 2：使用 w 命令 - -`w` 命令为每个登录进系统的用户，每个用户当前所做的事情，所有活动的负载对计算机的影响提供了一个快速的概要。这个单一命令结合了多个 Unix 程序：who，uptime，和 ps -a。 -``` -# w - - 08:35:14 up 21 days, 5:47, 1 user, load average: 0.26, 0.09, 0.02 -USER TTY FROM [email protected] IDLE JCPU PCPU WHAT -root pts/1 103.5.134.167 08:34 0.00s 0.01s 0.00s w - -``` - -### 方法 3：使用 top 命令 - -`top` 命令是 Linux 上监视实时系统进程的基础命令之一。它显示系统信息和运行进程的信息，例如正常运行时间，平均负载，运行的任务，登录用户数量，CPU 数量 & CPU 利用率，内存 & 交换空间信息。 - -**推荐阅读：**[TOP 命令监视服务器性能的例子][1] -``` -# top -c - -top - 08:36:01 up 21 days, 5:48, 1 user, load average: 0.12, 0.08, 0.02 -Tasks: 98 total, 1 running, 97 sleeping, 0 stopped, 0 zombie -Cpu(s): 0.0%us, 0.3%sy, 0.0%ni, 99.7%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st -Mem: 1872888k total, 1454644k used, 418244k free, 175804k buffers -Swap: 2097148k total, 0k used, 2097148k free, 1098140k cached - - PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND - 1 root 20 0 19340 1492 1172 S 0.0 0.1 0:01.04 /sbin/init - 2 root 20 0 0 0 0 S 0.0 0.0 0:00.00 [kthreadd] - 3 root RT 0 0 0 0 S 0.0 0.0 0:00.00 [migration/0] - 4 root 20 0 0 0 0 S 0.0 0.0 0:34.32 [ksoftirqd/0] - 5 root RT 0 0 0 0 S 0.0 0.0 0:00.00 [stopper/0] - -``` - -### 方法 4：使用 who 命令 - -`who` 命令列出当前登录进计算机的用户。`who` 命令与 `w` 命令类似，但后者还包含额外的数据和统计信息。 - -``` -# who -b - -system boot 2018-04-12 02:48 - -``` - -### 方法 5：使用 last 命令 - -`last` 命令列出最近登录过的用户。`last` 往回查找 `/var/log/wtmp` 文件并显示自从文件创建后登录进（出）的用户。 - -``` -# last reboot -F | head -1 | awk '{print $5,$6,$7,$8,$9}' - -Thu Apr 12 02:48:04 2018 - -``` - -### 方法 6：使用 /proc/uptime 文件 - -这个文件中包含系统上次启动后运行时间的详细信息。`/proc/uptime` 的输出相当精简。 - -第一个数字是系统自从启动的总秒数。第二个数字是总时间中系统空闲所花费的时间，以秒为单位。 - -``` -# cat /proc/uptime - -1835457.68 1809207.16 - -``` - -### 方法 7：使用 tuptime 命令 - -`tuptime` 是一个汇报系统运行时间的工具，输出历史信息并作以统计，保留重启之间的数据。和 `uptime` 命令很像，但输出更有意思一些。 - -``` -$ tuptime - -``` - -### 方法 8：使用 htop 命令 - -`htop` 是运行在 Linux 上一个由 Hisham 使用 ncurses 库开发的交互式进程查看器。`htop` 比起 `top` 有很多的特性和选项。 - -**推荐阅读：** [使用 Htop 命令监控系统资源][2] - -``` -# htop - - CPU[| 0.5%] Tasks: 48, 5 thr; 1 running - Mem[||||||||||||||||||||||||||||||||||||||||||||||||||| 165/1828MB] Load average: 0.10 0.05 0.01 - Swp[ 0/2047MB] Uptime: 21 days, 05:52:35 - - PID USER PRI NI VIRT RES SHR S CPU% MEM% TIME+ Command -29166 root 20 0 110M 2484 1240 R 0.0 0.1 0:00.03 htop -29580 root 20 0 11464 3500 1032 S 0.0 0.2 55:15.97 /bin/sh ./OSWatcher.sh 10 1 - 1 root 20 0 19340 1492 1172 S 0.0 0.1 0:01.04 /sbin/init - 486 root 16 -4 10780 900 348 S 0.0 0.0 0:00.07 /sbin/udevd -d - 748 root 18 -2 10780 932 360 S 0.0 0.0 0:00.00 /sbin/udevd -d - -``` - -### 方法 9：使用 glances 命令 - -`glances` 是一个跨平台基于 curses 使用 python 写的监控工具。我们可以说它非常强大，仅用一点空间就能获得很多信息。它使用 psutil 库从系统中获取信息。 - -`glances` 可以监控 CPU，内存，负载，进程，网络接口，磁盘 I/O，磁盘阵列RAID，传感器，文件系统（与文件夹），容器，显示器，Alert 日志，系统信息，运行时间，快速查看Quicklook（CPU，内存等）。 - -**推荐阅读：** [Glances （集大成）– Linux 上高级的实时系统运行监控工具][3] -``` -glances - -ubuntu (Ubuntu 17.10 64bit / Linux 4.13.0-37-generic) - IP 192.168.1.6/24 Uptime: 21 days, 05:55:15 - -CPU [|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||| 90.6%] CPU - 90.6% nice: 0.0% ctx_sw: 4K MEM \ 78.4% active: 942M SWAP - 5.9% LOAD 2-core -MEM [||||||||||||||||||||||||||||||||||||||||||||||||||||||||| 78.0%] user: 55.1% irq: 0.0% inter: 1797 total: 1.95G inactive: 562M total: 12.4G 1 min: 4.35 -SWAP [|||| 5.9%] system: 32.4% iowait: 1.8% sw_int: 897 used: 1.53G buffers: 14.8M used: 749M 5 min: 4.38 - idle: 7.6% steal: 0.0% free: 431M cached: 273M free: 11.7G 15 min: 3.38 - -NETWORK Rx/s Tx/s TASKS 211 (735 thr), 4 run, 207 slp, 0 oth sorted automatically by memory_percent, flat view -docker0 0b 232b -enp0s3 12Kb 4Kb Systemd 7 Services loaded: 197 active: 196 failed: 1 -lo 616b 616b -_h478e48e 0b 232b CPU% MEM% VIRT RES PID USER NI S TIME+ R/s W/s Command - 63.8 18.9 2.33G 377M 2536 daygeek 0 R 5:57.78 0 0 /usr/lib/firefox/firefox -contentproc -childID 1 -isForBrowser -intPrefs 6:50|7:-1|19:0|34:1000|42:20|43:5|44:10|51 -DefaultGateway 83ms 78.5 10.9 3.46G 217M 2039 daygeek 0 S 21:07.46 0 0 /usr/bin/gnome-shell - 8.5 10.1 2.32G 201M 2464 daygeek 0 S 8:45.69 0 0 /usr/lib/firefox/firefox -new-window -DISK I/O R/s W/s 1.1 8.5 2.19G 170M 2653 daygeek 0 S 2:56.29 0 0 /usr/lib/firefox/firefox -contentproc -childID 4 -isForBrowser -intPrefs 6:50|7:-1|19:0|34:1000|42:20|43:5|44:10|51 -dm-0 0 0 1.7 7.2 2.15G 143M 2880 daygeek 0 S 7:10.46 0 0 /usr/lib/firefox/firefox -contentproc -childID 6 -isForBrowser -intPrefs 6:50|7:-1|19:0|34:1000|42:20|43:5|44:10|51 -sda1 9.46M 12K 0.0 4.9 1.78G 97.2M 6125 daygeek 0 S 1:36.57 0 0 /usr/lib/firefox/firefox -contentproc -childID 7 -isForBrowser -intPrefs 6:50|7:-1|19:0|34:1000|42:20|43:5|44:10|51 - -``` - -### 方法 10：使用 stat 命令 - -`stat` 命令显示指定文件或文件系统的详细状态。 - -``` -# stat /var/log/dmesg | grep Modify - -Modify: 2018-04-12 02:48:04.027999943 -0400 - -``` - -### 方法 11：使用 procinfo 命令 - -`procinfo` 从 `/proc` 文件夹下收集一些系统数据并将其很好的格式化输出在标准输出设备上。 - -``` -# procinfo | grep Bootup - -Bootup: Fri Apr 20 19:40:14 2018 Load average: 0.16 0.05 0.06 1/138 16615 - -``` - --------------------------------------------------------------------------------- - -via: https://www.2daygeek.com/11-methods-to-find-check-system-server-uptime-in-linux/ - -作者：[Magesh Maruthamuthu][a] -选题：[lujun9972](https://github.com/lujun9972) -译者：[LuuMing](https://github.com/LuuMing) -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/ -[1]:https://www.2daygeek.com/top-command-examples-to-monitor-server-performance/ -[2]:https://www.2daygeek.com/htop-command-examples-to-monitor-system-resources/ -[3]:https://www.2daygeek.com/install-glances-advanced-real-time-linux-system-performance-monitoring-tool-on-centos-fedora-ubuntu-debian-opensuse-arch-linux/ diff --git a/translated/tech/20181211 Winterize your Bash prompt in Linux.md b/translated/tech/20181211 Winterize your Bash prompt in Linux.md new file mode 100644 index 0000000000..4e0a17be07 --- /dev/null +++ b/translated/tech/20181211 Winterize your Bash prompt in Linux.md @@ -0,0 +1,80 @@ +[#]: collector: (lujun9972) +[#]: translator: (geekpi) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Winterize your Bash prompt in Linux) +[#]: via: (https://opensource.com/article/18/12/linux-toy-bash-prompt) +[#]: author: (Jason Baker https://opensource.com/users/jason-baker) + +在 Linux 中冬季化你的 Bash 提示符 +====== +你的 Linux 终端可能支持 Unicode，那么为何不利用它在提示符中添加季节性的图标呢？ +![](https://opensource.com/sites/default/files/styles/image-full-size/public/uploads/linux-toy-bash-prompt.png?itok=HK_kVn37) + +欢迎再次来到 Linux 命令行玩具日历的另一篇。如果这是你第一次访问该系列，你甚至可能会问自己什么是命令行玩具？我们对此非常开放：它会是终端上有任何有趣的消遣，对于任何节日主题相关的还有额外的加分。 + +也许你以前见过其中的一些，也许你没有。不管怎样，我们希望你玩得开心。 + +今天的玩具非常简单：它是你的 Bash 提示符。你的 Bash 提示符？是的！我们还有几个星期的假期可以盯着它看，在北半球冬天还会再多几周，所以为什么不玩玩它。 + +目前你的 Bash 提示符号可能是一个简单的美元符号（ **$**），或者更有可能是一个更长的东西。如果你不确定你的 Bash 提示符是什么，你可以在环境变量 $PS1 中找到它。要查看它，请输入： + +``` +echo $PS1 +``` + +对于我而言，它返回： + +``` +[\u@\h \W]\$ +``` + +**\u**、 **\h** 和 **\W** 分别是用户名、主机名和工作目录的特殊字符。你还可以使用其他一些符号。为了帮助构建你的 Bash 提示符，你可以使用 [EzPrompt][1]，这是一个 PS1 配置的在线生成器，它包含了许多选项，包括日期和时间、Git 状态等。 + +你可能还有其他变量来组成 Bash 提示符。对我来说，**$PS2** 包含了我命令提示符的结束括号。有关详细信息，请参阅[这篇文章][2]。 + +要更改提示符，只需在终端中设置环境变量，如下所示： + +``` +$ PS1='\u is cold: ' +jehb is cold: +``` + +要永久设置它，请使用你喜欢的文本编辑器将相同的代码添加到 **/etc/bashrc** 中。 + +那么这些与冬季化有什么关系呢？好吧，你很有可能有现代机器，你的终端支持 Unicode，所以你不仅限于标准的 ASCII 字符集。你可以使用任何符合 Unicode 规范的 emoji，包括雪花 ❄、雪人 ☃ 或一对滑雪者 🎿。你有很多冬季 emoji 可供选择。 + +``` +🎄 圣诞树 +🧥 外套 +🦌 鹿 +🧤 手套 +🤶 圣诞夫人 +🎅 圣诞老人 +🧣 围巾 +🎿 滑雪者 +🏂 滑雪板 +❄ 雪花 +☃ 雪人 +⛄ 没有雪的雪人 +🎁 包装好的礼物 +``` +选择你最喜欢的，享受冬天的欢乐。有趣的事实：现代文件系统也支持文件名中的 Unicode 字符，这意味着技术上你可以将你下个程序命名为 **“❄❄❄❄❄.py”**。只是说说，不要这么做。 + +你有特别喜欢的命令行小玩具需要我介绍的吗？这个系列要介绍的小玩具大部分已经有了落实，但还预留了几个空位置。如果你有特别想了解的可以评论留言，我会查看的。如果还有空位置，我会考虑介绍它的。如果没有，但如果我得到了一些很好的意见，我会在最后做一些有价值的提及。 + +查看昨天的玩具，[在 Linux 终端玩贪吃蛇][3]，记得明天再来！ + +-------------------------------------------------------------------------------- +via: https://opensource.com/article/18/12/linux-toy-bash-prompt +作者：[Jason Baker][a] +选题：[lujun9972][b] +译者：[geekpi](https://github.com/geekpi) +校对：[校对者ID](https://github.com/校对者ID) +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 +[a]: https://opensource.com/users/jason-baker +[b]: https://github.com/lujun9972 +[1]: http://ezprompt.net/ +[2]: https://access.redhat.com/solutions/505983 +[3]: https://opensource.com/article/18/12/linux-toy-snake diff --git a/sources/tech/20181220 How To Install Microsoft .NET Core SDK On Linux.md b/translated/tech/20181220 How To Install Microsoft .NET Core SDK On Linux.md similarity index 52% rename from sources/tech/20181220 How To Install Microsoft .NET Core SDK On Linux.md rename to translated/tech/20181220 How To Install Microsoft .NET Core SDK On Linux.md index 728db3b7be..08b518e442 100644 --- a/sources/tech/20181220 How To Install Microsoft .NET Core SDK On Linux.md +++ b/translated/tech/20181220 How To Install Microsoft .NET Core SDK On Linux.md @@ -1,5 +1,5 @@ [#]: collector: (lujun9972) -[#]: translator: ( ) +[#]: translator: (runningwater) [#]: reviewer: ( ) [#]: publisher: ( ) [#]: url: ( ) @@ -7,20 +7,20 @@ [#]: via: (https://www.ostechnix.com/how-to-install-microsoft-net-core-sdk-on-linux/) [#]: author: (SK https://www.ostechnix.com/author/sk/) -How To Install Microsoft .NET Core SDK On Linux +如何在 Linux 中安装微软的 .NET Core SDK ====== ![](https://www.ostechnix.com/wp-content/uploads/2018/12/NET-Core-SDK-720x340.png) -The **.NET Core** is a free, cross platform and open source framework developed by Microsoft to build desktop applications, mobile apps, web apps, IoT apps and gaming apps etc. If you’re dotnet developer coming from Windows platform, .NET core helps you to setup your development environment easily on any Linux and Unix-like operating systems. This step by step guide explains how to install Microsoft .NET Core SDK on Linux and how to write your first app using .Net. +**.NET Core** 是微软提供的免费、跨平台和开源的开发框架，可以构建桌面应用程序、移动端应用程序、网络应用程序、物联网应用程序和游戏应用程序等。如果你是 Windows 平台下的 dotnet 开发人员的话，使用 .NET core 可以很轻松就设置好任何 Linux 和类 Unix 操作系统下的开发环境。本分步操作指南文章解释了如何在 Linux 中安装 .NET Core SDK 以及如何使用 .NET 开发出第一个应用程序。 -### Install Microsoft .NET Core SDK On Linux +### Linux 中安装 .NET Core SDK -The .NET core supports GNU/Linux, Mac OS and Windows. .Net core can be installed on popular GNU/Linux operating systems including Debian, Fedora, CentOS, Oracle Linux, RHEL, SUSE/openSUSE, and Ubuntu. As of writing this guide, the latest .NET core version was **2.2**. +.NET Core 支持 GNU/Linux、Mac OS 和 Windows 系统，可以在主流的 GNU/Linux 操作系统上安装运行，包括 Debian、Fedora、CentOS、Oracle Linux、RHEL、SUSE/openSUSE 和 Ubuntu 。在撰写这篇教程时，其最新版本为 **2.2**。 -On **Debian 9** , you can install .NET Core SDK as shown below. +**Debian 9** 系统上安装 .NET Core SDK，请按如下步骤进行。 -First of all, you need to register Microsoft key and add .NET repository by running the following commands: +首先，需要注册微软的密钥，接着把 .NET 源仓库地址添加进来，运行的命令如下： ``` $ wget -qO- https://packages.microsoft.com/keys/microsoft.asc | gpg --dearmor > microsoft.asc.gpg @@ -31,16 +31,16 @@ $ sudo chown root:root /etc/apt/trusted.gpg.d/microsoft.asc.gpg $ sudo chown root:root /etc/apt/sources.list.d/microsoft-prod.list ``` -After registering the key and adding the repository, install .NET SDK using commands: +注册好密钥及添加完仓库源后，就可以安装 .NET SDK 了，命令如下： ``` $ sudo apt-get update $ sudo apt-get install dotnet-sdk-2.2 ``` -**On Debian 8:** +**Debian 8 系统上安装:** -Add Microsoft key and enable .NET repository: +增加微软密钥，添加 .NET 仓库源： ``` $ wget -qO- https://packages.microsoft.com/keys/microsoft.asc | gpg --dearmor > microsoft.asc.gpg @@ -51,16 +51,16 @@ $ sudo chown root:root /etc/apt/trusted.gpg.d/microsoft.asc.gpg $ sudo chown root:root /etc/apt/sources.list.d/microsoft-prod.list ``` -Install .NET SDK: +安装 .NET SDK: ``` $ sudo apt-get update $ sudo apt-get install dotnet-sdk-2.2 ``` -**On Fedora 28:** +**Fedora 28 系统上安装:** -Add Microsoft key and enable .NET repository: +增加微软密钥，添加 .NET 仓库源： ``` $ sudo rpm --import https://packages.microsoft.com/keys/microsoft.asc @@ -69,14 +69,16 @@ $ sudo mv prod.repo /etc/yum.repos.d/microsoft-prod.repo $ sudo chown root:root /etc/yum.repos.d/microsoft-prod.repo ``` -Now, Install .NET SDK: +现在, 可以安装 .NET SDK 了: ``` $ sudo dnf update $ sudo dnf install dotnet-sdk-2.2 ``` -On **Fedora 27** , add the key and repository using commands: +**Fedora 27 系统下：** + +增加微软密钥，添加 .NET 仓库源，命令如下： ``` $ sudo rpm --import https://packages.microsoft.com/keys/microsoft.asc @@ -85,31 +87,31 @@ $ sudo mv prod.repo /etc/yum.repos.d/microsoft-prod.repo $ sudo chown root:root /etc/yum.repos.d/microsoft-prod.repo ``` -And install .NET SDK using commands: +接着安装 .NET SDK ，命令如下: ``` $ sudo dnf update $ sudo dnf install dotnet-sdk-2.2 ``` -**On CentOS/Oracle Linux:** +**CentOS/Oracle 版本的 Linux 系统上:** -Add Microsoft key and enable .NET core repository: +增加微软密钥，添加 .NET 仓库源，使其可用 ``` $ sudo rpm -Uvh https://packages.microsoft.com/config/rhel/7/packages-microsoft-prod.rpm ``` -Update the repositories and install .NET SDK: +更新源仓库，安装 .NET SDK: ``` $ sudo yum update $ sudo yum install dotnet-sdk-2.2 ``` -**On openSUSE Leap:** +**openSUSE Leap 版本的系统上:** -Add key, enable repository and install necessary dependencies using the following commands: +添加密钥，使仓库源可用，安装必需的依赖包，其命令如下： ``` $ sudo zypper install libicu @@ -119,29 +121,29 @@ $ sudo mv prod.repo /etc/zypp/repos.d/microsoft-prod.repo $ sudo chown root:root /etc/zypp/repos.d/microsoft-prod.repo ``` -Update the repositories and Install .NET SDK using commands: +更新源仓库，安装 .NET SDK，命令如下： ``` $ sudo zypper update $ sudo zypper install dotnet-sdk-2.2 ``` -**On Ubuntu 18.04 LTS:** +**Ubuntu 18.04 LTS 版本的系统上:** -Register the Microsoft key and .NET core repository using commands: +注册微软的密钥和 .NET Core 仓库源，命令如下： ``` $ wget -q https://packages.microsoft.com/config/ubuntu/18.04/packages-microsoft-prod.deb $ sudo dpkg -i packages-microsoft-prod.deb ``` -Enable ‘Universe’ repository using: +使 ‘Universe’ 仓库可用： ``` $ sudo add-apt-repository universe ``` -Then, install .NET Core SDK using command: +然后，安装 .NET Core SDK ，命令如下: ``` $ sudo apt-get install apt-transport-https @@ -149,16 +151,16 @@ $sudo apt-get update $ sudo apt-get install dotnet-sdk-2.2 ``` -**On Ubuntu 16.04 LTS:** +**Ubuntu 16.04 LTS 版本的系统上:** -Register Microsoft key and .NET repository using commands: +注册微软的密钥和 .NET Core 仓库源，命令如下： ``` $ wget -q https://packages.microsoft.com/config/ubuntu/16.04/packages-microsoft-prod.deb $ sudo dpkg -i packages-microsoft-prod.deb ``` -And then, Install .NET core SDK: +然后安装 .NET core SDK: ``` $ sudo apt-get install apt-transport-https @@ -166,17 +168,17 @@ $ sudo apt-get update $ sudo apt-get install dotnet-sdk-2.2 ``` -### Create Your First App +### 创建你的第一个应用程序 -We have successfully installed .Net Core SDK in our Linux box. It is time to create our first app using dotnet. +我们已经成功的在 Linux 机器中安装了 .NET Core SDK。是时候使用 dotnet 创建第一个应用程序了。 -For the purpose of this guide, I am going to create a new app called **“ostechnixApp”**. To do so, simply run the following command: +接下来的目的，我们会创建一个名为 **“ostechnixApp”** 的应用程序。为此，可以简单的运行如下命令： ``` $ dotnet new console -o ostechnixApp ``` -**Sample output:** +**简单的输出:** ``` Welcome to .NET Core! @@ -208,9 +210,9 @@ Restore completed in 894.27 ms for /home/sk/ostechnixApp/ostechnixApp.csproj. Restore succeeded. ``` -As you can see in the above output, .Net has created a new application of type console. The parameter -o creates a directory named “ostechnixApp” where you store your app data with all necessary files. +正如上面的输出所示的，.NET 已经为我们创建一个控制台类型的应用程序。`-o` 参数创建了一个名为 “ostechnixApp” 的目录，其包含有存储此应用程序数据所必需的文件。 -Let us switch to ostechnixApp directory and see what’s in there. +让我们切换到 ostechnixApp 目录，看看里面有些什么。 ``` $ cd ostechnixApp/ @@ -218,7 +220,7 @@ $ ls obj ostechnixApp.csproj Program.cs ``` -As you there are three files named **ostechnixApp.csproj** and **Program.cs** and one directory named **obj**. By default, the Program.cs file will contain the code to run the ‘Hello World’ program in the console. Let us have a look at the code. +可以看到有两个名为 **ostechnixApp.csproj** 和 **Program.cs** 的文件，以及一个名为 **ojb** 的目录。默认情况下, `Program.cs` 文件包含有可以在控制台中运行的 'Hello World' 程序代码。可以看看此代码： ``` $ cat Program.cs @@ -236,7 +238,7 @@ namespace ostechnixApp } ``` -To run the newly created app, simply run the following command: +要运行此应用程序，可以简单的使用如下命令： ``` $ dotnet run @@ -245,9 +247,9 @@ Hello World! ![](https://www.ostechnix.com/wp-content/uploads/2018/12/run-dotnet.png) -Simple, isn’t it? Yes, it is! Now, you can write your code in the **Program.cs** file and run it as shown above. +很简单，对吧？是的，就是如此简单。现在你可以在 **Program.cs** 这文件中写上自己的代码，然后像上面所示的执行。 -Alternatively, you can create a new directory, for example mycode, using commands: +或者，你可以创建一个新的目录，如例子所示的 `mycode` 目录，命令如下： ``` $ mkdir ~/.mycode @@ -255,13 +257,13 @@ $ mkdir ~/.mycode $ cd mycode/ ``` -…and make that as your new development environment by running the following command: +然后运行如下命令，使其成为你的新开发环境目录： ``` $ dotnet new console ``` -Sample output: +简单的输出: ``` The template "Console Application" was created successfully. @@ -276,46 +278,46 @@ Restore completed in 331.87 ms for /home/sk/mycode/mycode.csproj. Restore succeeded. ``` -The above command will create two files named **mycode.csproj** and **Program.cs** and one directory named **obj**. Open the Program.cs file in your favorite editor, delete or modify the existing ‘hello world’ code with your own code. +上的命令会创建两个名叫 **mycode.csproj** 和 **Program.cs** 的文件及一个名为 **obj** 的目录。用你喜欢的编辑器打开 `Program.cs` 文件, 删除或修改原来的 'hello world' 代码段，然后编写自己的代码。 -Once the code is written, save and close the Program.cs file and run the app using command: +写完代码，保存，关闭 Program.cs 文件，然后运行此应用程序，命令如下： ``` $ dotnet run ``` -To check the installed .NET core SDK version, simply run: +想要查看安装的 .NET core SDK 的版本的话，可以简单的运行： ``` $ dotnet --version 2.2.101 ``` -To get help, run: +要获得帮助，请运行： ``` $ dotnet --help ``` -### Get Microsoft Visual Studio Code Editor +### 使用微软的 Visual Studio Code 编辑器 -To write the code, you can use your favorite editors of your choice. Microsoft has also its own editor named “ **Microsoft Visual Studio Code** ” with support for .NET. It is an open source, lightweight and powerful source code editor. It comes with built-in support for JavaScript, TypeScript and Node.js and has a rich ecosystem of extensions for other languages (such as C++, C#, Python, PHP, Go) and runtimes (such as .NET and Unity). It is a cross-platform code editor, so you can use it in Microsoft Windows, GNU/Linux, and Mac OS X. You can use it if you’re interested. +要编写代码，你可以任选自己喜欢的编辑器。同时微软自己也有一款支持 .NET 的编辑器，其名为 “ **Microsoft Visual Studio Code** ”。它是一款开源、轻量级、功能强大的源代码编辑器。其内置了对 JavaScript、TypeScript 和 Node.js 的支持，并为其它语言（如 C++、C#、Python、PHP、Go）和运行时态（如 .NET 和 Unity）提供了丰富的扩展，已经形成一个完整的生态系统。它是一款跨平台的代码编辑器，所以在微软的 Windows 系统、GNU/Linux 系统和 Mac OS X 系统都可以使用。如果对其感兴趣，就可以使用。 -To know how to install and use it on Linux, please refer the following guide. +To know how to install and use it on Linux, please refer the following guide.想了解如何在 Linux 上安装和使用，请参阅以下指南。 -[Install Microsoft Visual Studio Code In Linux][3] +[Linux 中安装 Microsoft Visual Studio Code][3] -[**This page**][1] has some basic tutorials to learn .NET Core and .NET Core SDK tools using Visual Studio Code editor. Go and check them to learn more. +关于 Visual Studio Code editor 中 .NET Core 和 .NET Core SDK 工具的使用，[**此网页**][1]有一些基础的教程。想了解更多就去看看吧。 ### Telemetry -By default, the .NET core SDK will collect the usage data using a feature called **‘Telemetry’**. The collected data is anonymous and shared to the development team and community under the [Creative Commons Attribution License][2]. So the .NET team will understand how the tools are used and decide how they can be improved over time. If you don’t want to share your usage information, you can simply opt-out of telemetry by setting the **DOTNET_CLI_TELEMETRY_OPTOUT** environment variable to **‘1’** or **‘true’** using your favorite shell. +默认情况下，.NET core SDK 会采集用户使用情况数据，此功能被称为 **‘Telemetry’**。采集数据是匿名的，并根据[知识共享署名许可][2]分享给其开发团队和社区。因此 .NET 团队会知道这些工具的使用状况，然后根据统计做出决策，改进产品。如果你不想分享自己的使用信息的话，可以使用顺手的 shell 工具把名为 **DOTNET_CLI_TELEMETRY_OPTOUT** 的环境变量参数设置为 **‘1’** 或 **‘true’**，这样就简单的关闭此功能了。 -And, that’s all. You know how to install .NET Core SDK on various Linux platforms and how to create a basic app using it. TO learn more about .NET usage, refer the links given at the end of this guide. +就这样。你已经知道如何在各 Linux 平台上安装 .NET Core SDK 以及知道如何创建基本的应用程序了。想了解更多 .NET 使用知识的话，请参阅此文章末尾给出的链接。 -More good stuffs to come. Stay tuned! +会爆出更多干货的。敬请关注！ -Cheers! +祝贺下! @@ -325,7 +327,7 @@ via: https://www.ostechnix.com/how-to-install-microsoft-net-core-sdk-on-linux/ 作者：[SK][a] 选题：[lujun9972][b] -译者：[译者ID](https://github.com/译者ID) +译者：[runningwater](https://github.com/runningwater) 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