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published/20171124 How do groups work on Linux.md
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132
published/20171124 How do groups work on Linux.md
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@ -0,0 +1,132 @@
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||||
“用户组”在 Linux 上到底是怎么工作的？
|
||||
========
|
||||
|
||||
嗨！就在上周，我还自认为对 Linux 上的用户和组的工作机制了如指掌。我认为它们的关系是这样的：
|
||||
|
||||
1. 每个进程都属于一个用户（比如用户 `julia`）
|
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2. 当这个进程试图读取一个被某个组所拥有的文件时， Linux 会
|
||||
a. 先检查用户`julia` 是否有权限访问文件。（LCTT 译注：此处应该是指检查文件的所有者是否就是 `julia`）
|
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b. 检查 `julia` 属于哪些组，并进一步检查在这些组里是否有某个组拥有这个文件或者有权限访问这个文件。
|
||||
3. 如果上述 a、b 任一为真（或者“其它”位设为有权限访问），那么这个进程就有权限访问这个文件。
|
||||
|
||||
比如说，如果一个进程被用户 `julia` 拥有并且 `julia` 在`awesome` 组，那么这个进程就能访问下面这个文件。
|
||||
|
||||
```
|
||||
r--r--r-- 1 root awesome 6872 Sep 24 11:09 file.txt
|
||||
```
|
||||
|
||||
然而上述的机制我并没有考虑得非常清楚，如果你硬要我阐述清楚，我会说进程可能会在**运行时**去检查 `/etc/group` 文件里是否有某些组拥有当前的用户。
|
||||
|
||||
### 然而这并不是 Linux 里“组”的工作机制
|
||||
|
||||
我在上个星期的工作中发现了一件有趣的事，事实证明我前面的理解错了，我对组的工作机制的描述并不准确。特别是 Linux **并不会**在进程每次试图访问一个文件时就去检查这个进程的用户属于哪些组。
|
||||
|
||||
我在读了《[Linux 编程接口][1]》这本书的第九章（“进程资格”）后才恍然大悟（这本书真是太棒了），这才是组真正的工作方式！我意识到之前我并没有真正理解用户和组是怎么工作的，我信心满满的尝试了下面的内容并且验证到底发生了什么，事实证明现在我的理解才是对的。
|
||||
|
||||
### 用户和组权限检查是怎么完成的
|
||||
|
||||
现在这些关键的知识在我看来非常简单! 这本书的第九章上来就告诉我如下事实：用户和组 ID 是**进程的属性**，它们是：
|
||||
|
||||
* 真实用户 ID 和组 ID；
|
||||
* 有效用户 ID 和组 ID；
|
||||
* 保存的 set-user-ID 和保存的 set-group-ID；
|
||||
* 文件系统用户 ID 和组 ID（特定于 Linux);
|
||||
* 补充的组 ID；
|
||||
|
||||
这说明 Linux **实际上**检查一个进程能否访问一个文件所做的组检查是这样的：
|
||||
|
||||
* 检查一个进程的组 ID 和补充组 ID（这些 ID 就在进程的属性里，**并不是**实时在 `/etc/group` 里查找这些 ID）
|
||||
* 检查要访问的文件的访问属性里的组设置
|
||||
* 确定进程对文件是否有权限访问（LCTT 译注：即文件的组是否是以上的组之一）
|
||||
|
||||
通常当访问控制的时候使用的是**有效**用户/组 ID，而不是**真实**用户/组 ID。技术上来说当访问一个文件时使用的是**文件系统**的 ID，它们通常和有效用户/组 ID 一样。（LCTT 译注：这句话针对 Linux 而言。）
|
||||
|
||||
### 将一个用户加入一个组并不会将一个已存在的进程（的用户）加入那个组
|
||||
|
||||
下面是一个有趣的例子：如果我创建了一个新的组：`panda` 组并且将我自己（`bork`）加入到这个组，然后运行 `groups` 来检查我是否在这个组里：结果是我（`bork`）竟然不在这个组？！
|
||||
|
||||
```
|
||||
bork@kiwi~> sudo addgroup panda
|
||||
Adding group `panda' (GID 1001) ...
|
||||
Done.
|
||||
bork@kiwi~> sudo adduser bork panda
|
||||
Adding user `bork' to group `panda' ...
|
||||
Adding user bork to group panda
|
||||
Done.
|
||||
bork@kiwi~> groups
|
||||
bork adm cdrom sudo dip plugdev lpadmin sambashare docker lxd
|
||||
|
||||
```
|
||||
|
||||
`panda` 并不在上面的组里！为了再次确定我们的发现，让我们建一个文件，这个文件被 `panda` 组拥有，看看我能否访问它。
|
||||
|
||||
```
|
||||
$ touch panda-file.txt
|
||||
$ sudo chown root:panda panda-file.txt
|
||||
$ sudo chmod 660 panda-file.txt
|
||||
$ cat panda-file.txt
|
||||
cat: panda-file.txt: Permission denied
|
||||
```
|
||||
|
||||
好吧，确定了，我（`bork`）无法访问 `panda-file.txt`。这一点都不让人吃惊，我的命令解释器并没有将 `panda` 组作为补充组 ID，运行 `adduser bork panda` 并不会改变这一点。
|
||||
|
||||
### 那进程一开始是怎么得到用户的组的呢？
|
||||
|
||||
这真是个非常令人困惑的问题，对吗？如果进程会将组的信息预置到进程的属性里面，进程在初始化的时候怎么取到组的呢？很明显你无法给你自己指定更多的组（否则就会和 Linux 访问控制的初衷相违背了……）
|
||||
|
||||
有一点还是很清楚的：一个新的进程是怎么从我的命令行解释器（`/bash/fish`）里被**执行**而得到它的组的。（新的）进程将拥有我的用户 ID（`bork`），并且进程属性里还有很多组 ID。从我的命令解释器里执行的所有进程是从这个命令解释器里 `fork()` 而来的，所以这个新进程得到了和命令解释器同样的组。
|
||||
|
||||
因此一定存在一个“第一个”进程来把你的组设置到进程属性里，而所有由此进程而衍生的进程将都设置这些组。而那个“第一个”进程就是你的<ruby>登录程序<rt>login shell</rt></ruby>，在我的笔记本电脑上，它是由 `login` 程序（`/bin/login`）实例化而来。登录程序以 root 身份运行，然后调用了一个 C 的库函数 —— `initgroups` 来设置你的进程的组（具体来说是通过读取 `/etc/group` 文件），因为登录程序是以 root 运行的，所以它能设置你的进程的组。
|
||||
|
||||
### 让我们再登录一次
|
||||
|
||||
好了！假如说我们正处于一个登录程序中，而我又想刷新我的进程的组设置，从我们前面所学到的进程是怎么初始化组 ID 的，我应该可以通过再次运行登录程序来刷新我的进程组并启动一个新的登录命令！
|
||||
|
||||
让我们试试下边的方法：
|
||||
|
||||
```
|
||||
$ sudo login bork
|
||||
$ groups
|
||||
bork adm cdrom sudo dip plugdev lpadmin sambashare docker lxd panda
|
||||
$ cat panda-file.txt # it works! I can access the file owned by `panda` now!
|
||||
```
|
||||
|
||||
当然，成功了！现在由登录程序衍生的程序的用户是组 `panda` 的一部分了！太棒了！这并不会影响我其他的已经在运行的登录程序（及其子进程），如果我真的希望“所有的”进程都能对 `panda` 组有访问权限。我必须完全的重启我的登录会话，这意味着我必须退出我的窗口管理器然后再重新登录。（LCTT 译注：即更新进程树的树根进程，这里是窗口管理器进程。）
|
||||
|
||||
### newgrp 命令
|
||||
|
||||
在 Twitter 上有人告诉我如果只是想启动一个刷新了组信息的命令解释器的话，你可以使用 `newgrp`（LCTT 译注：不启动新的命令解释器），如下：
|
||||
|
||||
```
|
||||
sudo addgroup panda
|
||||
sudo adduser bork panda
|
||||
newgrp panda # starts a new shell, and you don't have to be root to run it!
|
||||
```
|
||||
|
||||
你也可以用 `sg panda bash` 来完成同样的效果，这个命令能启动一个`bash` 登录程序，而这个程序就有 `panda` 组。
|
||||
|
||||
### seduid 将设置有效用户 ID
|
||||
|
||||
其实我一直对一个进程如何以 `setuid root` 的权限来运行意味着什么有点似是而非。现在我知道了，事实上所发生的是：`setuid` 设置了
|
||||
“有效用户 ID”! 如果我（`julia`）运行了一个 `setuid root` 的进程（ 比如 `passwd`），那么进程的**真实**用户 ID 将为 `julia`，而**有效**用户 ID 将被设置为 `root`。
|
||||
|
||||
`passwd` 需要以 root 权限来运行，但是它能看到进程的真实用户 ID 是 `julia` ，是 `julia` 启动了这个进程，`passwd` 会阻止这个进程修改除了 `julia` 之外的用户密码。
|
||||
|
||||
### 就是这些了！
|
||||
|
||||
在《[Linux 编程接口][1]》这本书里有很多 Linux 上一些功能的罕见使用方法以及 Linux 上所有的事物到底是怎么运行的详细解释，这里我就不一一展开了。那本书棒极了，我上面所说的都在该书的第九章，这章在 1300 页的书里只占了 17 页。
|
||||
|
||||
我最爱这本书的一点是我只用读 17 页关于用户和组是怎么工作的内容，而这区区 17 页就能做到内容完备、详实有用。我不用读完所有的 1300 页书就能得到有用的东西，太棒了！
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://jvns.ca/blog/2017/11/20/groups/
|
||||
|
||||
作者：[Julia Evans][a]
|
||||
译者：[DavidChen](https://github.com/DavidChenLiang)
|
||||
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://jvns.ca/
|
||||
[1]:http://man7.org/tlpi/
|
||||
@ -1,8 +1,9 @@
|
||||
如何使用 Steam Play 在 Linux 上玩仅限 Windows 的游戏
|
||||
======
|
||||
Steam 的新实验功能允许你在 Linux 上玩仅限 Windows 的游戏。以下是如何在 Steam 中使用此功能。
|
||||
|
||||
你已经听说过这个消息。游戏发行平台[ Steam 正在实现一个 WINE 分支来允许你玩仅在 Windows 上的游戏][1]。对于 Linux 用户来说，这绝对是一个好消息，因为我们抱怨 Linux 的游戏数量不足。
|
||||
> Steam 的新实验功能允许你在 Linux 上玩仅限 Windows 的游戏。以下是如何在 Steam 中使用此功能。
|
||||
|
||||
你已经听说过这个消息。游戏发行平台 [Steam 正在复刻一个 WINE 分支来允许你玩仅限于 Windows 上的游戏][1]。对于 Linux 用户来说，这绝对是一个好消息，因为我们总抱怨 Linux 的游戏数量不足。
|
||||
|
||||
这个新功能仍处于测试阶段，但你现在可以在 Linux 上试用它并在 Linux 上玩仅限 Windows 的游戏。让我们看看如何做到这一点。
|
||||
|
||||
@ -14,20 +15,19 @@ Steam 的新实验功能允许你在 Linux 上玩仅限 Windows 的游戏。以
|
||||
|
||||
安装了 Steam 并且你已登录到 Steam 帐户，就可以了解如何在 Steam Linux 客户端中启用 Windows 游戏。
|
||||
|
||||
|
||||
#### 步骤 1：进入帐户设置
|
||||
|
||||
运行 Steam 客户端。在左上角，单击 Steam，然后单击 Settings。
|
||||
运行 Steam 客户端。在左上角，单击 “Steam”，然后单击 “Settings”。
|
||||
|
||||
![Enable steam play beta on Linux][4]
|
||||
|
||||
#### 步骤 2：选择加入测试计划
|
||||
|
||||
在“设置”中，从左侧窗口中选择“帐户”，然后单击 “Beta participation” 下的 “CHANGE” 按钮。
|
||||
在“Settings”中，从左侧窗口中选择“Account”，然后单击 “Beta participation” 下的 “CHANGE” 按钮。
|
||||
|
||||
![Enable beta feature in Steam Linux][5]
|
||||
|
||||
你应该在此处选择 Steam Beta Update。
|
||||
你应该在此处选择 “Steam Beta Update”。
|
||||
|
||||
![Enable beta feature in Steam Linux][6]
|
||||
|
||||
@ -37,32 +37,29 @@ Steam 的新实验功能允许你在 Linux 上玩仅限 Windows 的游戏。以
|
||||
|
||||
下载好 Steam 新的测试版更新后，它将重新启动。到这里就差不多了。
|
||||
|
||||
再次进入“设置”。你现在可以在左侧窗口看到新的 Steam Play 选项。单击它并选中复选框：
|
||||
再次进入“Settings”。你现在可以在左侧窗口看到新的 “Steam Play” 选项。单击它并选中复选框：
|
||||
|
||||
* Enable Steam Play for supported titles （你可以玩列入白名单的 Windows 游戏）
|
||||
* Enable Steam Play for all titles （你可以尝试玩所有仅限 Windows 的游戏）
|
||||
|
||||
|
||||
|
||||
![Play Windows games on Linux using Steam Play][7]
|
||||
|
||||
我不记得 Steam 是否会再次重启，但我想这是微不足道的。你现在应该可以在 Linux 上看到安装仅限 Windows 的游戏的选项了。
|
||||
我不记得 Steam 是否会再次重启，但我想这无所谓。你现在应该可以在 Linux 上看到安装仅限 Windows 的游戏的选项了。
|
||||
|
||||
比如，我的 Steam 库中有 Age of Empires，正常情况下这个在 Linux 中没有。但我在 Steam Play 测试版启用所有 Windows 游戏后，现在我可以选择在 Linux 上安装 Age of Empires 了。
|
||||
比如，我的 Steam 库中有《Age of Empires》，正常情况下这个在 Linux 中没有。但我在 Steam Play 测试版启用所有 Windows 游戏后，现在我可以选择在 Linux 上安装《Age of Empires》了。
|
||||
|
||||
![Install Windows-only games on Linux using Steam][8]
|
||||
现在可以在 Linux 上安装仅限 Windows 的游戏
|
||||
|
||||
*现在可以在 Linux 上安装仅限 Windows 的游戏*
|
||||
|
||||
### 有关 Steam Play 测试版功能的信息
|
||||
|
||||
在 Linux 上使用 Steam Play 测试版玩仅限 Windows 的游戏有一些事情你需要知道并且牢记。
|
||||
|
||||
* If you have games downloaded on Windows via Steam, you can save some download data by [sharing Steam game files between Linux and Windows][12].
|
||||
* 目前，[只有 27 个 Steam Play 中的 Windows 游戏被列入白名单][9]。这些白名单游戏在 Linux 上无缝运行。
|
||||
* 你可以使用 Steam Play 测试版尝试任何 Windows 游戏，但它可能无法一直运行。有些游戏有时会崩溃，而某些游戏可能根本无法运行。
|
||||
* 目前，[只有 27 个 Steam Play 中的 Windows 游戏被列入白名单][9]。这些白名单游戏可以在 Linux 上无缝运行。
|
||||
* 你可以使用 Steam Play 测试版尝试任何 Windows 游戏，但它可能不是总能运行。有些游戏有时会崩溃，而某些游戏可能根本无法运行。
|
||||
* 在测试版中，你无法 Steam 商店中看到适用于 Linux 的 Windows 限定游戏。你必须自己尝试游戏或参考[这个社区维护的列表][10]以查看该 Windows 游戏的兼容性状态。你也可以通过填写[此表][11]来为列表做出贡献。
|
||||
* 如果你通过 Steam 在 Windows 上下载游戏，那么可以通过[在 Linux 和 Windows 之间共享 Steam 游戏文件][12]来保存一些下载数据。
|
||||
|
||||
* 如果你在 Windows 中通过 Steam 下载了游戏，你可以[在 Linux 和 Windows 之间共享 Steam 游戏文件][12]来节省下载的数据。
|
||||
|
||||
我希望本教程能帮助你在 Linux 上运行仅限 Windows 的游戏。你期待在 Linux 上玩哪些游戏？
|
||||
|
||||
@ -73,12 +70,12 @@ via: https://itsfoss.com/steam-play/
|
||||
作者：[Abhishek Prakash][a]
|
||||
选题：[lujun9972](https://github.com/lujun9972)
|
||||
译者：[geekpi](https://github.com/geekpi)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
校对：[wxy](https://github.com/wxy)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://itsfoss.com/author/abhishek/
|
||||
[1]:https://itsfoss.com/steam-play-proton/
|
||||
[1]:https://linux.cn/article-10054-1.html
|
||||
[2]:https://4bds6hergc-flywheel.netdna-ssl.com/wp-content/uploads/2018/08/play-windows-games-on-linux-featured.jpeg
|
||||
[3]:https://itsfoss.com/install-steam-ubuntu-linux/
|
||||
[4]:https://4bds6hergc-flywheel.netdna-ssl.com/wp-content/uploads/2018/08/enable-steam-play-beta.jpeg
|
||||
@ -89,4 +86,4 @@ via: https://itsfoss.com/steam-play/
|
||||
[9]:https://steamcommunity.com/games/221410
|
||||
[10]:https://docs.google.com/spreadsheets/d/1DcZZQ4HL_Ol969UbXJmFG8TzOHNnHoj8Q1f8DIFe8-8/htmlview?sle=true#
|
||||
[11]:https://docs.google.com/forms/d/e/1FAIpQLSeefaYQduMST_lg0IsYxZko8tHLKe2vtVZLFaPNycyhY4bidQ/viewform
|
||||
[12]:https://itsfoss.com/share-steam-files-linux-windows/
|
||||
[12]:https://linux.cn/article-8027-1.html
|
||||
@ -1,14 +1,15 @@
|
||||
让你提高效率的 Linux 技巧
|
||||
======
|
||||
想要在 Linux 命令行工作中提高效率，你需要使用一些技巧。
|
||||
|
||||
> 想要在 Linux 命令行工作中提高效率，你需要使用一些技巧。
|
||||
|
||||
|
||||
|
||||
巧妙的 Linux 命令行技巧能让你节省时间、避免出错，还能让你记住和复用各种复杂的命令，专注在需要做的事情本身，而不是做事的方式。以下介绍一些好用的命令行技巧。
|
||||
巧妙的 Linux 命令行技巧能让你节省时间、避免出错，还能让你记住和复用各种复杂的命令，专注在需要做的事情本身，而不是你要怎么做。以下介绍一些好用的命令行技巧。
|
||||
|
||||
### 命令编辑
|
||||
|
||||
如果要对一个已输入的命令进行修改，可以使用 ^a（ctrl + a）或 ^e（ctrl + e）将光标快速移动到命令的开头或命令的末尾。
|
||||
如果要对一个已输入的命令进行修改，可以使用 `^a`（`ctrl + a`）或 `^e`（`ctrl + e`）将光标快速移动到命令的开头或命令的末尾。
|
||||
|
||||
还可以使用 `^` 字符实现对上一个命令的文本替换并重新执行命令，例如 `^before^after^` 相当于把上一个命令中的 `before` 替换为 `after` 然后重新执行一次。
|
||||
|
||||
@ -59,11 +60,11 @@ alias show_dimensions='xdpyinfo | grep '\''dimensions:'\'''
|
||||
|
||||
### 冻结、解冻终端界面
|
||||
|
||||
^s（ctrl + s）将通过执行流量控制命令 XOFF 来停止终端输出内容，这会对 PuTTY 会话和桌面终端窗口产生影响。如果误输入了这个命令，可以使用 ^q（ctrl + q）让终端重新响应。所以只需要记住^q 这个组合键就可以了，毕竟这种情况并不多见。
|
||||
`^s`（`ctrl + s`）将通过执行流量控制命令 XOFF 来停止终端输出内容，这会对 PuTTY 会话和桌面终端窗口产生影响。如果误输入了这个命令，可以使用 `^q`（`ctrl + q`）让终端重新响应。所以只需要记住 `^q` 这个组合键就可以了，毕竟这种情况并不多见。
|
||||
|
||||
### 复用命令
|
||||
|
||||
Linux 提供了很多让用户复用命令的方法，其核心是通过历史缓冲区收集执行过的命令。复用命令的最简单方法是输入 `!` 然后接最近使用过的命令的开头字母；当然也可以按键盘上的向上箭头，直到看到要复用的命令，然后按 Enter 键。还可以先使用 `history` 显示命令历史，然后输入 `!` 后面再接命令历史记录中需要复用的命令旁边的数字。
|
||||
Linux 提供了很多让用户复用命令的方法，其核心是通过历史缓冲区收集执行过的命令。复用命令的最简单方法是输入 `!` 然后接最近使用过的命令的开头字母；当然也可以按键盘上的向上箭头，直到看到要复用的命令，然后按回车键。还可以先使用 `history` 显示命令历史，然后输入 `!` 后面再接命令历史记录中需要复用的命令旁边的数字。
|
||||
|
||||
```
|
||||
!! <== 复用上一条命令
|
||||
@ -129,7 +130,7 @@ $ rm -i <== 请求确认
|
||||
$ unalias rm
|
||||
```
|
||||
|
||||
如果已经将 `rm -i` 默认设置为 `rm` 的别名，但你希望在删除文件之前不必进行确认，则可以将 `unalias` 命令放在一个启动文件（例如 ~/.bashrc）中。
|
||||
如果已经将 `rm -i` 默认设置为 `rm` 的别名，但你希望在删除文件之前不必进行确认，则可以将 `unalias` 命令放在一个启动文件（例如 `~/.bashrc`）中。
|
||||
|
||||
### 使用 sudo
|
||||
|
||||
@ -151,8 +152,6 @@ md () { mkdir -p "$@" && cd "$1"; }
|
||||
|
||||
使用 Linux 命令行是在 Linux 系统上工作最有效也最有趣的方法，但配合命令行技巧和巧妙的别名可以让你获得更好的体验。
|
||||
|
||||
加入 [Facebook][1] 和 [LinkedIn][2] 上的 Network World 社区可以和我们一起讨论。
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.networkworld.com/article/3305811/linux/linux-tricks-that-even-you-can-love.html
|
||||
@ -160,7 +159,7 @@ via: https://www.networkworld.com/article/3305811/linux/linux-tricks-that-even-y
|
||||
作者：[Sandra Henry-Stocker][a]
|
||||
选题：[lujun9972](https://github.com/lujun9972)
|
||||
译者：[HankChow](https://github.com/HankChow)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
校对：[wxy](https://github.com/wxy)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
@ -1,170 +0,0 @@
|
||||
Translating by z52527
|
||||
|
||||
|
||||
A Cat Clone With Syntax Highlighting And Git Integration
|
||||
======
|
||||
|
||||
|
||||
|
||||
In Unix-like systems, we use **‘cat’** command to print and concatenate files. Using cat command, we can print the contents of a file to the standard output, concatenate several files into the target file, and append several files into the target file. Today, I stumbled upon a similar utility named **“Bat”** , a clone to the cat command, with some additional cool features such as syntax highlighting, git integration and automatic paging etc. In this brief guide, we will how to install and use Bat command in Linux.
|
||||
|
||||
### Installation
|
||||
|
||||
Bat is available in the default repositories of Arch Linux. So, you can install it using pacman on any arch-based systems.
|
||||
```
|
||||
$ sudo pacman -S bat
|
||||
|
||||
```
|
||||
|
||||
On Debian, Ubuntu, Linux Mint systems, download the **.deb** file from the [**Releases page**][1] and install it as shown below.
|
||||
```
|
||||
$ sudo apt install gdebi
|
||||
|
||||
$ sudo gdebi bat_0.5.0_amd64.deb
|
||||
|
||||
```
|
||||
|
||||
For other systems, you may need to compile and install from source. Make sure you have installed Rust 1.26 or higher.
|
||||
|
||||
|
||||
|
||||
Then, run the following command to install Bat:
|
||||
```
|
||||
$ cargo install bat
|
||||
|
||||
```
|
||||
|
||||
Alternatively, you can install it using [**Linuxbrew**][2] package manager.
|
||||
```
|
||||
$ brew install bat
|
||||
|
||||
```
|
||||
|
||||
### Bat command Usage
|
||||
|
||||
The Bat command’s usage is very similar to cat command.
|
||||
|
||||
To create a new file using bat command, do:
|
||||
```
|
||||
$ bat > file.txt
|
||||
|
||||
```
|
||||
|
||||
To view the contents of a file using bat command, just do:
|
||||
```
|
||||
$ bat file.txt
|
||||
|
||||
```
|
||||
|
||||
You can also view multiple files at once:
|
||||
```
|
||||
$ bat file1.txt file2.txt
|
||||
|
||||
```
|
||||
|
||||
To append the contents of the multiple files in a single file:
|
||||
```
|
||||
$ bat file1.txt file2.txt file3.txt > document.txt
|
||||
|
||||
```
|
||||
|
||||
Like I already mentioned, apart from viewing and editing files, the Bat command has some additional cool features though.
|
||||
|
||||
The bat command supports **syntax highlighting** for large number of programming and markup languages. For instance, look at the following example. I am going to display the contents of the **reverse.py** file using both cat and bat commands.
|
||||
|
||||
|
||||
|
||||
Did you notice the difference? Cat command shows the contents of the file in plain text format, whereas bat command shows output with syntax highlighting, order number in a neat tabular column format. Much better, isn’t it?
|
||||
|
||||
If you want to display only the line numbers (not the tabular column), use **-n** flag.
|
||||
```
|
||||
$ bat -n reverse.py
|
||||
|
||||
```
|
||||
|
||||
**Sample output:**
|
||||
|
||||
|
||||
Another notable feature of Bat command is it supports **automatic paging**. That means if output of a file is too large for one screen, the bat command automatically pipes its own output to **less** command, so you can view the output page by page.
|
||||
|
||||
Let me show you an example. When you view the contents of a file which spans multiple pages using cat command, the prompt quickly jumps to the last page of the file, and you do not see the content in the beginning or in the middle.
|
||||
|
||||
Have a look at the following output:
|
||||
|
||||
|
||||
|
||||
As you can see, the cat command displays last page of the file.
|
||||
|
||||
So, you may need to pipe the output of the cat command to **less** command to view it’s contents page by page from the beginning.
|
||||
```
|
||||
$ cat reverse.py | less
|
||||
|
||||
```
|
||||
|
||||
Now, you can view output page by page by hitting the ENTER key. However, it is not necessary if you use bat command. The bat command will automatically pipe the output of a file which spans multiple pages.
|
||||
```
|
||||
$ bat reverse.py
|
||||
|
||||
```
|
||||
|
||||
**Sample output:**
|
||||
|
||||
|
||||
|
||||
Now hit the ENTER key to go to the next page.
|
||||
|
||||
The bat command also supports **GIT integration** , so you can view/edit the files in your Git repository without much hassle. It communicates with git to show modifications with respect to the index (see left side bar).
|
||||
|
||||
|
||||
|
||||
**Customizing Bat**
|
||||
|
||||
If you don’t like the default themes, you can change it too. Bat has option for that too.
|
||||
|
||||
To list the available themes, just run:
|
||||
```
|
||||
$ bat --list-themes
|
||||
1337
|
||||
DarkNeon
|
||||
Default
|
||||
GitHub
|
||||
Monokai Extended
|
||||
Monokai Extended Bright
|
||||
Monokai Extended Light
|
||||
Monokai Extended Origin
|
||||
TwoDark
|
||||
|
||||
```
|
||||
|
||||
To use a different theme, for example TwoDark, run:
|
||||
```
|
||||
$ bat --theme=TwoDark file.txt
|
||||
|
||||
```
|
||||
|
||||
If you want to make the theme permanent, use `export BAT_THEME="TwoDark"` in your shells startup file.
|
||||
|
||||
Bat also have the option to control the appearance of the output. To do so, use the `--style` option. To show only Git changes and line numbers but no grid and no file header, use `--style=numbers,changes`.
|
||||
|
||||
For more details, refer the Bat project GitHub Repository (Link at the end).
|
||||
|
||||
And, that’s all for now. Hope this was useful. More good stuffs to come. Stay tuned!
|
||||
|
||||
Cheers!
|
||||
|
||||
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.ostechnix.com/bat-a-cat-clone-with-syntax-highlighting-and-git-integration/
|
||||
|
||||
作者：[SK][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://www.ostechnix.com/author/sk/
|
||||
[1]:https://github.com/sharkdp/bat/releases
|
||||
[2]:https://www.ostechnix.com/linuxbrew-common-package-manager-linux-mac-os-x/
|
||||
116
sources/tech/20180928 10 handy Bash aliases for Linux.md
Normal file
116
sources/tech/20180928 10 handy Bash aliases for Linux.md
Normal file
@ -0,0 +1,116 @@
|
||||
10 handy Bash aliases for Linux
|
||||
======
|
||||
Get more efficient by using condensed versions of long Bash commands.
|
||||
|
||||
|
||||
|
||||
How many times have you repeatedly typed out a long command on the command line and wished there was a way to save it for later? This is where Bash aliases come in handy. They allow you to condense long, cryptic commands down to something easy to remember and use. Need some examples to get you started? No problem!
|
||||
|
||||
To use a Bash alias you've created, you need to add it to your .bash_profile file, which is located in your home folder. Note that this file is hidden and accessible only from the command line. The easiest way to work with this file is to use something like Vi or Nano.
|
||||
|
||||
### 10 handy Bash aliases
|
||||
|
||||
1. How many times have you needed to unpack a .tar file and couldn't remember the exact arguments needed? Aliases to the rescue! Just add the following to your .bash_profile file and then use **untar FileName** to unpack any .tar file.
|
||||
|
||||
|
||||
|
||||
```
|
||||
alias untar='tar -zxvf '
|
||||
|
||||
```
|
||||
|
||||
2. Want to download something but be able to resume if something goes wrong?
|
||||
|
||||
|
||||
|
||||
```
|
||||
alias wget='wget -c '
|
||||
|
||||
```
|
||||
|
||||
3. Need to generate a random, 20-character password for a new online account? No problem.
|
||||
|
||||
|
||||
|
||||
```
|
||||
alias getpass="openssl rand -base64 20"
|
||||
|
||||
```
|
||||
|
||||
4. Downloaded a file and need to test the checksum? We've got that covered too.
|
||||
|
||||
|
||||
|
||||
```
|
||||
alias sha='shasum -a 256 '
|
||||
|
||||
```
|
||||
|
||||
5. A normal ping will go on forever. We don't want that. Instead, let's limit that to just five pings.
|
||||
|
||||
|
||||
|
||||
```
|
||||
alias ping='ping -c 5'
|
||||
|
||||
```
|
||||
|
||||
6. Start a web server in any folder you'd like.
|
||||
|
||||
|
||||
|
||||
```
|
||||
alias www='python -m SimpleHTTPServer 8000'
|
||||
|
||||
```
|
||||
|
||||
7. Want to know how fast your network is? Just download Speedtest-cli and use this alias. You can choose a server closer to your location by using the **speedtest-cli --list** command.
|
||||
|
||||
|
||||
|
||||
```
|
||||
alias speed='speedtest-cli --server 2406 --simple'
|
||||
|
||||
```
|
||||
|
||||
8. How many times have you needed to know your external IP address and had no idea how to get that info? Yeah, me too.
|
||||
|
||||
|
||||
|
||||
```
|
||||
alias ipe='curl ipinfo.io/ip'
|
||||
|
||||
```
|
||||
|
||||
9. Need to know your local IP address?
|
||||
|
||||
|
||||
|
||||
```
|
||||
alias ipi='ipconfig getifaddr en0'
|
||||
|
||||
```
|
||||
|
||||
10. Finally, let's clear the screen.
|
||||
|
||||
|
||||
|
||||
```
|
||||
alias c='clear'
|
||||
|
||||
```
|
||||
|
||||
As you can see, Bash aliases are a super-easy way to simplify your life on the command line. Want more info? I recommend a quick Google search for "Bash aliases" or a trip to GitHub.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/18/9/handy-bash-aliases
|
||||
|
||||
作者：[Patrick H.Mullins][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/pmullins
|
||||
@ -0,0 +1,111 @@
|
||||
A Free And Secure Online PDF Conversion Suite
|
||||
======
|
||||
|
||||
|
||||
|
||||
We are always in search for a better and more efficient solution that can make our lives more convenient. That is why when you are working with PDF documents you need a fast and reliable tool that you can use in every situation. Therefore, we wanted to introduce you to **EasyPDF** Online PDF Suite for every occasion. The promise behind this tool is that it can make your PDF management easier and we tested it to check that claim.
|
||||
|
||||
But first, here are the most important things you need to know about EasyPDF:
|
||||
|
||||
* EasyPDF is free and anonymous online PDF Conversion Suite.
|
||||
* Convert PDF to Word, Excel, PowerPoint, AutoCAD, JPG, GIF and Text.
|
||||
* Create PDF from Word, PowerPoint, JPG, Excel files and many other formats.
|
||||
* Manipulate PDFs with PDF Merge, Split and Compress.
|
||||
* OCR conversion of scanned PDFs and images.
|
||||
* Upload files from your device or the Cloud (Google Drive and DropBox).
|
||||
* Available on Windows, Linux, Mac, and smartphones via any browser.
|
||||
* Multiple languages supported.
|
||||
|
||||
|
||||
|
||||
### EasyPDF User Interface
|
||||
|
||||
|
||||
|
||||
One of the first things that catches your eye is the sleek user interface which gives the tool clean and functional environment in where you can work comfortably. The whole experience is even better because there are no ads on a website at all.
|
||||
|
||||
All different types of conversions have their dedicated menu with a simple box to add files, so you don’t have to wonder about what you need to do.
|
||||
|
||||
Most websites aren’t optimized to work well and run smoothly on mobile phones, but EasyPDF is an exception from that rule. It opens almost instantly on smartphone and is easy to navigate. You can also add it as the shortcut on your home screen from the **three dots menu** on the Chrome app.
|
||||
|
||||
|
||||
|
||||
### Functionality
|
||||
|
||||
Apart from looking nice, EasyPDF is pretty straightforward to use. You **don’t need to register** or leave an **email** to use the tool. It is completely anonymous. Additionally, it doesn’t put any limitations to the number or size of files for conversion. No installation required either! Cool, yeah?
|
||||
|
||||
You choose a desired conversion format, for example, PDF to Word. Select the PDF file you want to convert. You can upload a file from the device by either drag & drop or selecting the file from the folder. There is also an option to upload a document from [**Google Drive**][1] or [**Dropbox**][2].
|
||||
|
||||
After you choose the file, press the Convert button to start the conversion process. You won’t wait for a long time to get your file because conversion will finish in a minute. If you have some more files to convert, remember to download the file before you proceed further. If you don’t download the document first, you will lose it.
|
||||
|
||||
|
||||
|
||||
For a different type of conversion, return to the homepage.
|
||||
|
||||
The currently available types of conversions are:
|
||||
|
||||
* **PDF to Word** – Convert PDF documents to Word documents
|
||||
|
||||
* **PDF to PowerPoint** – Convert PDF documents to PowerPoint Presentations
|
||||
|
||||
* **PDF to Excel** – Convert PDF documents to Excel documents
|
||||
|
||||
* **PDF Creation** – Create PDF documents from any type of file (E.g text, doc, odt)
|
||||
|
||||
* **Word to PDF** – Convert Word documents to PDF documents
|
||||
|
||||
* **JPG to PDF** – Convert JPG images to PDF documents
|
||||
|
||||
* **PDF to AutoCAD** – Convert PDF documents to .dwg format (DWG is native format for CAD packages)
|
||||
|
||||
* **PDF to Text** – Convert PDF documents to Text documents
|
||||
|
||||
* **PDF Split** – Split PDF files into multiple parts
|
||||
|
||||
* **PDF Merge** – Merge multiple PDF files into one
|
||||
|
||||
* **PDF Compress** – Compress PDF documents
|
||||
|
||||
* **PDF to JPG** – Convert PDF documents to JPG images
|
||||
|
||||
* **PDF to PNG** – Convert PDF documents to PNG images
|
||||
|
||||
* **PDF to GIF** – Convert PDF documents to GIF files
|
||||
|
||||
* **OCR Online** –
|
||||
|
||||
Convert scanned paper documents
|
||||
|
||||
to editable files (E.g Word, Excel, Text)
|
||||
|
||||
|
||||
|
||||
|
||||
Want to give it a try? Great! Click the following link and start converting!
|
||||
|
||||
[][https://easypdf.com/]
|
||||
|
||||
### Conclusion
|
||||
|
||||
EasyPDF lives up to its name and enables easier PDF management. As far as I tested EasyPDF service, It offers out of the box conversion feature completely **FREE!** It is fast, secure and reliable. You will find the quality of services most satisfying without having to pay anything or leaving your personal data like email address. Give it a try and who knows maybe you will find your new favorite PDF tool.
|
||||
|
||||
And, that’s all for now. More good stuffs to come. Stay tuned!
|
||||
|
||||
Cheers!
|
||||
|
||||
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.ostechnix.com/easypdf-a-free-and-secure-online-pdf-conversion-suite/
|
||||
|
||||
作者：[SK][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://www.ostechnix.com/author/sk/
|
||||
[1]: https://www.ostechnix.com/how-to-mount-google-drive-locally-as-virtual-file-system-in-linux/
|
||||
[2]: https://www.ostechnix.com/install-dropbox-in-ubuntu-18-04-lts-desktop/
|
||||
@ -0,0 +1,233 @@
|
||||
How to Install Popcorn Time on Ubuntu 18.04 and Other Linux Distributions
|
||||
======
|
||||
**Brief: This tutorial shows you how to install Popcorn Time on Ubuntu and other Linux distributions. Some handy Popcorn Time tips have also been discussed.**
|
||||
|
||||
[Popcorn Time][1] is an open source [Netflix][2] inspired [torrent][3] streaming application for Linux, Mac and Windows.
|
||||
|
||||
With the regular torrents, you have to wait for the download to finish before you could watch the videos.
|
||||
|
||||
[Popcorn Time][4] is different. It uses torrent underneath but allows you to start watching the videos (almost) immediately. It’s like you are watching videos on streaming websites like YouTube or Netflix. You don’t have to wait for the download to finish here.
|
||||
|
||||
![Popcorn Time in Ubuntu Linux][5]
|
||||
Popcorn Time
|
||||
|
||||
If you want to watch movies online without those creepy ads, Popcorn Time is a good alternative. Keep in mind that the streaming quality depends on the number of available seeds.
|
||||
|
||||
Popcorn Time also provides a nice user interface where you can browse through available movies, tv-series and other contents. If you ever used [Netflix on Linux][6], you will find it’s somewhat a similar experience.
|
||||
|
||||
Using torrent to download movies is illegal in several countries where there are strict laws against piracy. In countries like the USA, UK and West European you may even get legal notices. That said, it’s up to you to decide if you want to use it or not. You have been warned.
|
||||
(If you still want to take the risk and use Popcorn Time, you should use a VPN service like [Ivacy][7] that has been specifically designed for using Torrents and protecting your identity. Even then it’s not always easy to avoid the snooping authorities.)
|
||||
|
||||
Some of the main features of Popcorn Time are:
|
||||
|
||||
* Watch movies and TV Series online using Torrent
|
||||
* A sleek user interface lets you browse the available movies and TV series
|
||||
* Change streaming quality
|
||||
* Bookmark content for watching later
|
||||
* Download content for offline viewing
|
||||
* Ability to enable subtitles by default, change the subtitles size etc
|
||||
* Keyboard shortcuts to navigate through Popcorn Time
|
||||
|
||||
|
||||
|
||||
### How to install Popcorn Time on Ubuntu and other Linux Distributions
|
||||
|
||||
I am using Ubuntu 18.04 in this tutorial but you can use the same instructions for other Linux distributions such as Linux Mint, Debian, Manjaro, Deepin etc.
|
||||
|
||||
Let’s see how to install Popcorn time on Linux. It’s really easy actually. Simply follow the instructions and copy paste the commands I have mentioned.
|
||||
|
||||
#### Step 1: Download Popcorn Time
|
||||
|
||||
You can download Popcorn Time from its official website. The download link is present on the homepage itself.
|
||||
|
||||
[Get Popcorn Time](https://popcorntime.sh/)
|
||||
|
||||
#### Step 2: Install Popcorn Time
|
||||
|
||||
Once you have downloaded Popcorn Time, it’s time to use it. The downloaded file is a tar file that consists of an executable among other files. While you can extract this tar file anywhere, the [Linux convention is to install additional software in][8] /[opt directory.][8]
|
||||
|
||||
Create a new directory in /opt:
|
||||
|
||||
```
|
||||
sudo mkdir /opt/popcorntime
|
||||
```
|
||||
|
||||
Now go to the Downloads directory.
|
||||
|
||||
```
|
||||
cd ~/Downloads
|
||||
```
|
||||
|
||||
Extract the downloaded Popcorn Time files into the newly created /opt/popcorntime directory.
|
||||
|
||||
```
|
||||
sudo tar Jxf Popcorn-Time-* -C /opt/popcorntime
|
||||
```
|
||||
|
||||
#### Step 3: Make Popcorn Time accessible for everyone
|
||||
|
||||
You would want every user on your system to be able to run Popcorn Time without sudo access, right? To do that, you need to create a [symbolic link][9] to the executable in /usr/bin directory.
|
||||
|
||||
```
|
||||
ln -sf /opt/popcorntime/Popcorn-Time /usr/bin/Popcorn-Time
|
||||
```
|
||||
|
||||
#### Step 4: Create desktop launcher for Popcorn Time
|
||||
|
||||
So far so good. But you would also like to see Popcorn Time in the application menu, add it to your favorite application list etc.
|
||||
|
||||
For that, you need to create a desktop entry.
|
||||
|
||||
Open a terminal and create a new file named popcorntime.desktop in /usr/share/applications.
|
||||
|
||||
You can use any [command line based text editor][10]. Ubuntu has [Nano][11] installed by default so you can use that.
|
||||
|
||||
```
|
||||
sudo nano /usr/share/applications/popcorntime.desktop
|
||||
```
|
||||
|
||||
Insert the following lines here:
|
||||
|
||||
```
|
||||
[Desktop Entry]
|
||||
Version = 1.0
|
||||
Type = Application
|
||||
Terminal = false
|
||||
Name = Popcorn Time
|
||||
Exec = /usr/bin/Popcorn-Time
|
||||
Icon = /opt/popcorntime/popcorn.png
|
||||
Categories = Application;
|
||||
```
|
||||
|
||||
If you used Nano editor, save it using shortcut Ctrl+X. When asked for saving, enter Y and then press enter again to save and exit.
|
||||
|
||||
We are almost there. One last thing to do here is to have the correct icon for Popcorn Time. For that, you can download a Popcorn Time icon and save it as popcorn.png in /opt/popcorntime directory.
|
||||
|
||||
You can do that using the command below:
|
||||
|
||||
```
|
||||
sudo wget -O /opt/popcorntime/popcorn.png https://upload.wikimedia.org/wikipedia/commons/d/df/Pctlogo.png
|
||||
|
||||
```
|
||||
|
||||
That’s it. Now you can search for Popcorn Time and click on it to launch it.
|
||||
|
||||
![Popcorn Time installed on Ubuntu][12]
|
||||
Search for Popcorn Time in Menu
|
||||
|
||||
On the first launch, you’ll have to accept the terms and conditions.
|
||||
|
||||
![Popcorn Time in Ubuntu Linux][13]
|
||||
Accept the Terms of Service
|
||||
|
||||
Once you do that, you can enjoy the movies and TV shows.
|
||||
|
||||
![Watch movies on Popcorn Time][14]
|
||||
|
||||
Well, that’s all you needed to install Popcorn Time on Ubuntu or any other Linux distribution. You can start watching your favorite movies straightaway.
|
||||
|
||||
However, if you are interested, I would suggest reading these Popcorn Time tips to get more out of it.
|
||||
|
||||
[![][15]][16]
|
||||
![][17]
|
||||
|
||||
### 7 Tips for using Popcorn Time effectively
|
||||
|
||||
Now that you have installed Popcorn Time, I am going to tell you some nifty Popcorn Time tricks. I assure you that it will enhance your experience with Popcorn Time multiple folds.
|
||||
|
||||
#### 1\. Use advanced settings
|
||||
|
||||
Always have the advanced settings enabled. It gives you more options to tweak Popcorn Time. Go to the top right corner and click on the gear symbol. Click on it and check advanced settings on the next screen.
|
||||
|
||||
|
||||
|
||||
#### 2\. Watch the movies in VLC or other players
|
||||
|
||||
Did you know that you can choose to watch a file in your preferred media player instead of the default Popcorn Time player? Of course, that media player should have been installed in the system.
|
||||
|
||||
Now you may ask why would one want to use another player. And my answer is because other players like VLC has hidden features which you might not find in the Popcorn Time player.
|
||||
|
||||
For example, if a file has very low volume, you can use VLC to enhance the audio by 400 percent. You can also [synchronize incoherent subtitles with VLC][18]. You can switch between media players before you start to play a file:
|
||||
|
||||
|
||||
|
||||
#### 3\. Bookmark movies and watch it later
|
||||
|
||||
Just browsing through movies and TV series but don’t have time or mood to watch those? No issues. You can add the movies to the bookmark and can access these bookmarked videos from the Favorites tab. This enables you to create a list of movies you would watch later.
|
||||
|
||||
|
||||
|
||||
#### 4\. Check torrent health and seed information
|
||||
|
||||
As I had mentioned earlier, your viewing experience in Popcorn Times depends on torrent speed. Good thing is that Popcorn time shows the health of the torrent file so that you can be aware of the streaming speed.
|
||||
|
||||
You will see a green/yellow/red dot on the file. Green means there are plenty of seeds and the file will stream easily. Yellow means a medium number of seeds, streaming should be okay. Red means there are very few seeds available and the streaming will be poor or won’t work at all.
|
||||
|
||||
|
||||
|
||||
#### 5\. Add custom subtitles
|
||||
|
||||
If you need subtitles and it is not available in your preferred language, you can add custom subtitles downloaded from external websites. Get the .srt files and use it inside Popcorn Time:
|
||||
|
||||
|
||||
|
||||
This is where VLC comes handy as you can [download subtitles automatically with VLC][19].
|
||||
|
||||
|
||||
#### 6\. Save the files for offline viewing
|
||||
|
||||
When Popcorn Times stream a content, it downloads it and store temporarily. When you close the app, it’s cleaned out. You can change this behavior so that the downloaded file remains there for your future use.
|
||||
|
||||
In the advanced settings, scroll down a bit. Look for Cache directory. You can change this to some other directory like Downloads. This way, even if you close Popcorn Time, the file will be available for viewing.
|
||||
|
||||
|
||||
|
||||
#### 7\. Drag and drop external torrent files to play immediately
|
||||
|
||||
I bet you did not know about this one. If you don’t find a certain movie on Popcorn Time, download the torrent file from your favorite torrent website. Open Popcorn Time and just drag and drop the torrent file in Popcorn Time. It will start playing the file, depending upon seeds. This way, you don’t need to download the entire file before watching it.
|
||||
|
||||
When you drag and drop the torrent file in Popcorn Time, it will give you the option to choose which video file should it play. If there are subtitles in it, it will play automatically or else, you can add external subtitles.
|
||||
|
||||
|
||||
|
||||
There are plenty of other features in Popcorn Time. But I’ll stop with my list here and let you explore Popcorn Time on Ubuntu Linux. I hope you find these Popcorn Time tips and tricks useful.
|
||||
|
||||
I am repeating again. Using Torrents is illegal in many countries. If you do that, take precaution and use a VPN service. If you are looking for my recommendation, you can go for [Swiss-based privacy company ProtonVPN][20] (of [ProtonMail][21] fame). Singapore based [Ivacy][7] is another good option. If you think these are expensive, you can look for [cheap VPN deals on It’s FOSS Shop][22].
|
||||
|
||||
Note: This article contains affiliate links. Please read our [affiliate policy][23].
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://itsfoss.com/popcorn-time-ubuntu-linux/
|
||||
|
||||
作者：[Abhishek Prakash][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://itsfoss.com/author/abhishek/
|
||||
[1]: https://popcorntime.sh/
|
||||
[2]: https://netflix.com/
|
||||
[3]: https://en.wikipedia.org/wiki/Torrent_file
|
||||
[4]: https://en.wikipedia.org/wiki/Popcorn_Time
|
||||
[5]: https://4bds6hergc-flywheel.netdna-ssl.com/wp-content/uploads/2018/09/popcorn-time-linux.jpeg
|
||||
[6]: https://itsfoss.com/netflix-firefox-linux/
|
||||
[7]: https://billing.ivacy.com/page/23628
|
||||
[8]: http://tldp.org/LDP/Linux-Filesystem-Hierarchy/html/opt.html
|
||||
[9]: https://en.wikipedia.org/wiki/Symbolic_link
|
||||
[10]: https://itsfoss.com/command-line-text-editors-linux/
|
||||
[11]: https://itsfoss.com/nano-3-release/
|
||||
[12]: https://4bds6hergc-flywheel.netdna-ssl.com/wp-content/uploads/2018/09/popcorn-time-ubuntu-menu.jpg
|
||||
[13]: https://4bds6hergc-flywheel.netdna-ssl.com/wp-content/uploads/2018/09/popcorn-time-ubuntu-license.jpeg
|
||||
[14]: https://4bds6hergc-flywheel.netdna-ssl.com/wp-content/uploads/2018/09/popcorn-time-watch-movies.jpeg
|
||||
[15]: https://ivacy.postaffiliatepro.com/accounts/default1/vdegzkxbw/7f82d531.png
|
||||
[16]: https://billing.ivacy.com/page/23628/7f82d531
|
||||
[17]: http://ivacy.postaffiliatepro.com/scripts/vdegzkxiw?aff=23628&a_bid=7f82d531
|
||||
[18]: https://itsfoss.com/how-to-synchronize-subtitles-with-movie-quick-tip/
|
||||
[19]: https://itsfoss.com/download-subtitles-automatically-vlc-media-player-ubuntu/
|
||||
[20]: https://protonvpn.net/?aid=chmod777
|
||||
[21]: https://itsfoss.com/protonmail/
|
||||
[22]: https://shop.itsfoss.com/search?utf8=%E2%9C%93&query=vpn
|
||||
[23]: https://itsfoss.com/affiliate-policy/
|
||||
544
sources/tech/20180928 Using Grails with jQuery and DataTables.md
Normal file
544
sources/tech/20180928 Using Grails with jQuery and DataTables.md
Normal file
@ -0,0 +1,544 @@
|
||||
Using Grails with jQuery and DataTables
|
||||
======
|
||||
|
||||
Learn to build a Grails-based data browser that lets users visualize complex tabular data.
|
||||
|
||||
|
||||
|
||||
I’m a huge fan of [Grails][1]. Granted, I’m mostly a data person who likes to explore and analyze data using command-line tools. But even data people sometimes need to _look at_ the data, and sometimes using data means having a great data browser. With Grails, [jQuery][2], and the [DataTables jQuery plugin][3], we can make really nice tabular data browsers.
|
||||
|
||||
The [DataTables website][3] offers a lot of decent “recipe-style” documentation that shows how to put together some fine sample applications, and it includes the necessary JavaScript, HTML, and occasional [PHP][4] to accomplish some pretty spiffy stuff. But for those who would rather use Grails as their backend, a bit of interpretation is necessary. Also, the sample application data used is a single flat table of employees of a fictional company, so the complexity of dealing with table relations serves as an exercise for the reader.
|
||||
|
||||
In this article, we’ll fill those two gaps by creating a Grails application with a slightly more complex data structure and a DataTables browser. In doing so, we’ll cover Grails criteria, which are [Groovy][5] -fied Java Hibernate criteria. I’ve put the code for the application on [GitHub][6] , so this article is oriented toward explaining the nuances of the code.
|
||||
|
||||
For prerequisites, you will need Java, Groovy, and Grails environments set up. With Grails, I tend to use a terminal window and [Vim][7], so that’s what’s used here. To get a modern Java, I suggest downloading and installing the [Open Java Development Kit][8] (OpenJDK) provided by your Linux distro (which should be Java 8, 9, 10 or 11; at the time of writing, I’m working with Java 8). From my point of view, the best way to get up-to-date Groovy and Grails is to use [SDKMAN!][9].
|
||||
|
||||
Readers who have never tried Grails will probably need to do some background reading. As a starting point, I recommend [Creating Your First Grails Application][10].
|
||||
|
||||
### Getting the employee browser application
|
||||
|
||||
As mentioned above, I’ve put the source code for this sample employee browser application on [GitHub][6]. For further explanation, the application **embrow** was built using the following commands in a Linux terminal window:
|
||||
|
||||
```
|
||||
cd Projects
|
||||
grails create-app com.nuevaconsulting.embrow
|
||||
```
|
||||
|
||||
The domain classes and unit tests are created as follows:
|
||||
|
||||
```
|
||||
grails create-domain-class com.nuevaconsulting.embrow.Position
|
||||
grails create-domain-class com.nuevaconsulting.embrow.Office
|
||||
grails create-domain-class com.nuevaconsulting.embrow.Employeecd embrowgrails createdomaincom.grails createdomaincom.grails createdomaincom.
|
||||
```
|
||||
|
||||
The domain classes built this way have no attributes, so they must be edited as follows:
|
||||
|
||||
The Position domain class:
|
||||
|
||||
```
|
||||
package com.nuevaconsulting.embrow
|
||||
|
||||
class Position {
|
||||
|
||||
String name
|
||||
int starting
|
||||
|
||||
static constraints = {
|
||||
name nullable: false, blank: false
|
||||
starting nullable: false
|
||||
}
|
||||
}com.Stringint startingstatic constraintsnullableblankstarting nullable
|
||||
```
|
||||
|
||||
The Office domain class:
|
||||
|
||||
```
|
||||
package com.nuevaconsulting.embrow
|
||||
|
||||
class Office {
|
||||
|
||||
String name
|
||||
String address
|
||||
String city
|
||||
String country
|
||||
|
||||
static constraints = {
|
||||
name nullable: false, blank: false
|
||||
address nullable: false, blank: false
|
||||
city nullable: false, blank: false
|
||||
country nullable: false, blank: false
|
||||
}
|
||||
}
|
||||
```
|
||||
|
||||
And the Employee domain class:
|
||||
|
||||
```
|
||||
package com.nuevaconsulting.embrow
|
||||
|
||||
class Employee {
|
||||
|
||||
String surname
|
||||
String givenNames
|
||||
Position position
|
||||
Office office
|
||||
int extension
|
||||
Date hired
|
||||
int salary
|
||||
static constraints = {
|
||||
surname nullable: false, blank: false
|
||||
givenNames nullable: false, blank: false
|
||||
: false
|
||||
office nullable: false
|
||||
extension nullable: false
|
||||
hired nullable: false
|
||||
salary nullable: false
|
||||
}
|
||||
}
|
||||
```
|
||||
|
||||
Note that whereas the Position and Office domain classes use predefined Groovy types String and int, the Employee domain class defines fields that are of type Position and Office (as well as the predefined Date). This causes the creation of the database table in which instances of Employee are stored to contain references, or foreign keys, to the tables in which instances of Position and Office are stored.
|
||||
|
||||
Now you can generate the controllers, views, and various other test components:
|
||||
|
||||
```
|
||||
-all com.nuevaconsulting.embrow.Position
|
||||
grails generate-all com.nuevaconsulting.embrow.Office
|
||||
grails generate-all com.nuevaconsulting.embrow.Employeegrails generateall com.grails generateall com.grails generateall com.
|
||||
```
|
||||
|
||||
At this point, you have a basic create-read-update-delete (CRUD) application ready to go. I’ve included some base data in the **grails-app/init/com/nuevaconsulting/BootStrap.groovy** to populate the tables.
|
||||
|
||||
If you run the application with the command:
|
||||
|
||||
```
|
||||
grails run-app
|
||||
```
|
||||
|
||||
you will see the following screen in the browser at **<http://localhost:8080/:>**
|
||||
|
||||
![Embrow home screen][12]
|
||||
|
||||
The Embrow application home screen
|
||||
|
||||
Clicking on the link for the OfficeController gives you a screen that looks like this:
|
||||
|
||||
![Office list][14]
|
||||
|
||||
The office list
|
||||
|
||||
Note that this list is generated by the **OfficeController index** method and displayed by the view `office/index.gsp`.
|
||||
|
||||
Similarly, clicking on the **EmployeeController** gives a screen that looks like this:
|
||||
|
||||
![Employee controller][16]
|
||||
|
||||
The employee controller
|
||||
|
||||
Ok, that’s pretty ugly—what’s with the Position and Office links?
|
||||
|
||||
Well, the views generated by the `generate-all` commands above create an **index.gsp** file that uses the Grails <f:table/> tag that by default shows the class name ( **com.nuevaconsulting.embrow.Position** ) and the persistent instance identifier ( **30** ). This behavior can be customized to yield something better looking, and there is some pretty neat stuff with the autogenerated links, the autogenerated pagination, and the autogenerated sortable columns.
|
||||
|
||||
But even when it's fully cleaned up, this employee browser offers limited functionality. For example, what if you want to find all employees whose position includes the text “dev”? What if you want to combine columns for sorting so that the primary sort key is a surname and the secondary sort key is an office name? Or what if you want to export a sorted subset to a spreadsheet or PDF to email to someone who doesn’t have access to the browser?
|
||||
|
||||
The jQuery DataTables plugin provides this kind of extra functionality and allows you to create a full-fledged tabular data browser.
|
||||
|
||||
### Creating the employee browser view and controller methods
|
||||
|
||||
In order to create an employee browser based on jQuery DataTables, you must complete two tasks:
|
||||
|
||||
1. Create a Grails view that incorporates the HTML and JavaScript required to enable the DataTables
|
||||
|
||||
2. Add a method to the Grails controller to handle the new view
|
||||
|
||||
|
||||
|
||||
|
||||
#### The employee browser view
|
||||
|
||||
In the directory **embrow/grails-app/views/employee** , start by making a copy of the **index.gsp** file, calling it **browser.gsp** :
|
||||
|
||||
```
|
||||
cd Projects
|
||||
cd embrow/grails-app/views/employee
|
||||
cp gsp browser.gsp
|
||||
```
|
||||
|
||||
At this point, you want to customize the new **browser.gsp** file to add the relevant jQuery DataTables code.
|
||||
|
||||
As a rule, I like to grab my JavaScript and CSS from a content provider when feasible; to do so in this case, after the line:
|
||||
|
||||
```
|
||||
<title><g:message code="default.list.label" args="[entityName]" /></title>
|
||||
```
|
||||
|
||||
insert the following lines:
|
||||
|
||||
```
|
||||
<script src="https://code.jquery.com/jquery-2.2.4.min.js" integrity="sha256-BbhdlvQf/xTY9gja0Dq3HiwQF8LaCRTXxZKRutelT44=" crossorigin="anonymous"></script>
|
||||
<link rel="stylesheet" type="text/css" href="https://cdn.datatables.net/1.10.16/css/jquery.dataTables.css">
|
||||
<script type="text/javascript" charset="utf8" src="https://cdn.datatables.net/1.10.16/js/jquery.dataTables.js"></script>
|
||||
<link rel="stylesheet" type="text/css" href="https://cdn.datatables.net/scroller/1.4.4/css/scroller.dataTables.min.css">
|
||||
<script type="text/javascript" charset="utf8" src="https://cdn.datatables.net/scroller/1.4.4/js/dataTables.scroller.min.js"></script>
|
||||
<script type="text/javascript" charset="utf8" src="https://cdn.datatables.net/buttons/1.5.1/js/dataTables.buttons.min.js"></script>
|
||||
<script type="text/javascript" charset="utf8" src="https://cdn.datatables.net/buttons/1.5.1/js/buttons.flash.min.js"></script>
|
||||
<script type="text/javascript" charset="utf8" src="https://cdnjs.cloudflare.com/ajax/libs/jszip/3.1.3/jszip.min.js"></script>
|
||||
<script type="text/javascript" charset="utf8" src="https://cdnjs.cloudflare.com/ajax/libs/pdfmake/0.1.32/pdfmake.min.js"></script>
|
||||
<script type="text/javascript" charset="utf8" src="https://cdnjs.cloudflare.com/ajax/libs/pdfmake/0.1.32/vfs_fonts.js"></script>
|
||||
<script type="text/javascript" charset="utf8" src="https://cdn.datatables.net/buttons/1.5.1/js/buttons.html5.min.js"></script>
|
||||
<script type="text/javascript" charset="utf8" src="https://cdn.datatables.net/buttons/1.5.1/js/buttons.print.min.js "></script>
|
||||
```
|
||||
|
||||
Next, remove the code that provided the data pagination in **index.gsp** :
|
||||
|
||||
```
|
||||
<div id="list-employee" class="content scaffold-list" role="main">
|
||||
<h1><g:message code="default.list.label" args="[entityName]" /></h1>
|
||||
<g:if test="${flash.message}">
|
||||
<div class="message" role="status">${flash.message}</div>
|
||||
</g:if>
|
||||
<f:table collection="${employeeList}" />
|
||||
|
||||
<div class="pagination">
|
||||
<g:paginate total="${employeeCount ?: 0}" />
|
||||
</div>
|
||||
</div>
|
||||
```
|
||||
|
||||
and insert the code that materializes the jQuery DataTables.
|
||||
|
||||
The first part to insert is the HTML that creates the basic tabular structure of the browser. For the application where DataTables talks to a database backend, provide only the table headers and footers; the DataTables JavaScript takes care of the table contents.
|
||||
|
||||
```
|
||||
<div id="employee-browser" class="content" role="main">
|
||||
<h1>Employee Browser</h1>
|
||||
<table id="employee_dt" class="display compact" style="width:99%;">
|
||||
<thead>
|
||||
<tr>
|
||||
<th>Surname</th>
|
||||
<th>Given name(s)</th>
|
||||
<th>Position</th>
|
||||
<th>Office</th>
|
||||
<th>Extension</th>
|
||||
<th>Hired</th>
|
||||
<th>Salary</th>
|
||||
</tr>
|
||||
</thead>
|
||||
<tfoot>
|
||||
<tr>
|
||||
<th>Surname</th>
|
||||
<th>Given name(s)</th>
|
||||
<th>Position</th>
|
||||
<th>Office</th>
|
||||
<th>Extension</th>
|
||||
<th>Hired</th>
|
||||
<th>Salary</th>
|
||||
</tr>
|
||||
</tfoot>
|
||||
</table>
|
||||
</div>
|
||||
```
|
||||
|
||||
Next, insert a JavaScript block, which serves three primary functions: It sets the size of the text boxes shown in the footer for column filtering, it establishes the DataTables table model, and it creates a handler to do the column filtering.
|
||||
|
||||
```
|
||||
<g:javascript>
|
||||
$('#employee_dt tfoot th').each( function() {javascript
|
||||
```
|
||||
|
||||
The code below handles sizing the filter boxes at the bottoms of the table columns:
|
||||
|
||||
```
|
||||
var title = $(this).text();
|
||||
if (title == 'Extension' || title == 'Hired')
|
||||
$(this).html('<input type="text" size="5" placeholder="' + title + '?" />');
|
||||
else
|
||||
$(this).html('<input type="text" size="15" placeholder="' + title + '?" />');
|
||||
});titletitletitletitletitle
|
||||
```
|
||||
|
||||
Next, define the table model. This is where all the table options are provided, including the scrolling, rather than paginated, nature of the interface, the cryptic decorations to be provided according to the dom string, the ability to export data to CSV and other formats, as well as where the Ajax connection to the server is established. Note that the URL is created with a Groovy GString call to the Grails **createLink()** method, referring to the **browserLister** action in the **EmployeeController**. Also of interest is the definition of the columns of the table. This information is sent across to the back end, which queries the database and returns the appropriate records.
|
||||
|
||||
```
|
||||
var table = $('#employee_dt').DataTable( {
|
||||
"scrollY": 500,
|
||||
"deferRender": true,
|
||||
"scroller": true,
|
||||
"dom": "Brtip",
|
||||
"buttons": [ 'copy', 'csv', 'excel', 'pdf', 'print' ],
|
||||
"processing": true,
|
||||
"serverSide": true,
|
||||
"ajax": {
|
||||
"url": "${createLink(controller: 'employee', action: 'browserLister')}",
|
||||
"type": "POST",
|
||||
},
|
||||
"columns": [
|
||||
{ "data": "surname" },
|
||||
{ "data": "givenNames" },
|
||||
{ "data": "position" },
|
||||
{ "data": "office" },
|
||||
{ "data": "extension" },
|
||||
{ "data": "hired" },
|
||||
{ "data": "salary" }
|
||||
]
|
||||
});
|
||||
```
|
||||
|
||||
Finally, monitor the filter columns for changes and use them to apply the filter(s).
|
||||
|
||||
```
|
||||
table.columns().every(function() {
|
||||
var that = this;
|
||||
$('input', this.footer()).on('keyup change', function(e) {
|
||||
if (that.search() != this.value && 8 < e.keyCode && e.keyCode < 32)
|
||||
that.search(this.value).draw();
|
||||
});
|
||||
```
|
||||
|
||||
And that’s it for the JavaScript. This completes the changes to the view code.
|
||||
|
||||
```
|
||||
});
|
||||
</g:javascript>
|
||||
```
|
||||
|
||||
Here’s a screenshot of the UI this view creates:
|
||||
|
||||
|
||||
|
||||
Here’s another screenshot showing the filtering and multi-column sorting at work (looking for employees whose positions include the characters “dev”, ordering first by office, then by surname):
|
||||
|
||||
|
||||
|
||||
Here’s another screenshot, showing what happens when you click on the CSV button:
|
||||
|
||||
|
||||
|
||||
And finally, here’s a screenshot showing the CSV data opened in LibreOffice:
|
||||
|
||||
|
||||
|
||||
Ok, so the view part looked pretty straightforward; therefore, the controller action must do all the heavy lifting, right? Let’s see…
|
||||
|
||||
#### The employee controller browserLister action
|
||||
|
||||
Recall that we saw this string
|
||||
|
||||
```
|
||||
"${createLink(controller: 'employee', action: 'browserLister')}"
|
||||
```
|
||||
|
||||
as the URL used for the Ajax calls from the DataTables table model. [createLink() is the method][17] behind a Grails tag that is used to dynamically generate a link as the HTML is preprocessed on the Grails server. This ends up generating a link to the **EmployeeController** , located in
|
||||
|
||||
```
|
||||
embrow/grails-app/controllers/com/nuevaconsulting/embrow/EmployeeController.groovy
|
||||
```
|
||||
|
||||
and specifically to the controller method **browserLister()**. I’ve left some print statements in the code so that the intermediate results can be seen in the terminal window where the application is running.
|
||||
|
||||
```
|
||||
def browserLister() {
|
||||
// Applies filters and sorting to return a list of desired employees
|
||||
```
|
||||
|
||||
First, print out the parameters passed to **browserLister()**. I usually start building controller methods with this code so that I’m completely clear on what my controller is receiving.
|
||||
|
||||
```
|
||||
println "employee browserLister params $params"
|
||||
println()
|
||||
```
|
||||
|
||||
Next, process those parameters to put them in a more usable shape. First, the jQuery DataTables parameters, a Groovy map called **jqdtParams** :
|
||||
|
||||
```
|
||||
def jqdtParams = [:]
|
||||
params.each { key, value ->
|
||||
def keyFields = key.replace(']','').split(/\[/)
|
||||
def table = jqdtParams
|
||||
for (int f = 0; f < keyFields.size() - 1; f++) {
|
||||
def keyField = keyFields[f]
|
||||
if (!table.containsKey(keyField))
|
||||
table[keyField] = [:]
|
||||
table = table[keyField]
|
||||
}
|
||||
table[keyFields[-1]] = value
|
||||
}
|
||||
println "employee dataTableParams $jqdtParams"
|
||||
println()
|
||||
```
|
||||
|
||||
Next, the column data, a Groovy map called **columnMap** :
|
||||
|
||||
```
|
||||
def columnMap = jqdtParams.columns.collectEntries { k, v ->
|
||||
def whereTerm = null
|
||||
switch (v.data) {
|
||||
case 'extension':
|
||||
case 'hired':
|
||||
case 'salary':
|
||||
if (v.search.value ==~ /\d+(,\d+)*/)
|
||||
whereTerm = v.search.value.split(',').collect { it as Integer }
|
||||
break
|
||||
default:
|
||||
if (v.search.value ==~ /[A-Za-z0-9 ]+/)
|
||||
whereTerm = "%${v.search.value}%" as String
|
||||
break
|
||||
}
|
||||
[(v.data): [where: whereTerm]]
|
||||
}
|
||||
println "employee columnMap $columnMap"
|
||||
println()
|
||||
```
|
||||
|
||||
Next, a list of all column names, retrieved from **columnMap** , and a corresponding list of how those columns should be ordered in the view, Groovy lists called **allColumnList** and **orderList** , respectively:
|
||||
|
||||
```
|
||||
def allColumnList = columnMap.keySet() as List
|
||||
println "employee allColumnList $allColumnList"
|
||||
def orderList = jqdtParams.order.collect { k, v -> [allColumnList[v.column as Integer], v.dir] }
|
||||
println "employee orderList $orderList"
|
||||
```
|
||||
|
||||
We’re going to use Grails’ implementation of Hibernate criteria to actually carry out the selection of elements to be displayed as well as their ordering and pagination. Criteria requires a filter closure; in most examples, this is given as part of the creation of the criteria instance itself, but here we define the filter closure beforehand. Note in this case the relatively complex interpretation of the “date hired” filter, which is treated as a year and applied to establish date ranges, and the use of **createAlias** to allow us to reach into related classes Position and Office:
|
||||
|
||||
```
|
||||
def filterer = {
|
||||
createAlias 'position', 'p'
|
||||
createAlias 'office', 'o'
|
||||
|
||||
if (columnMap.surname.where) ilike 'surname', columnMap.surname.where
|
||||
if (columnMap.givenNames.where) ilike 'givenNames', columnMap.givenNames.where
|
||||
if (columnMap.position.where) ilike 'p.name', columnMap.position.where
|
||||
if (columnMap.office.where) ilike 'o.name', columnMap.office.where
|
||||
if (columnMap.extension.where) inList 'extension', columnMap.extension.where
|
||||
if (columnMap.salary.where) inList 'salary', columnMap.salary.where
|
||||
if (columnMap.hired.where) {
|
||||
if (columnMap.hired.where.size() > 1) {
|
||||
or {
|
||||
columnMap.hired.where.each {
|
||||
between 'hired', Date.parse('yyyy/MM/dd',"${it}/01/01" as String),
|
||||
Date.parse('yyyy/MM/dd',"${it}/12/31" as String)
|
||||
}
|
||||
}
|
||||
} else {
|
||||
between 'hired', Date.parse('yyyy/MM/dd',"${columnMap.hired.where[0]}/01/01" as String),
|
||||
Date.parse('yyyy/MM/dd',"${columnMap.hired.where[0]}/12/31" as String)
|
||||
}
|
||||
}
|
||||
}
|
||||
```
|
||||
|
||||
At this point, it’s time to apply the foregoing. The first step is to get a total count of all the Employee instances, required by the pagination code:
|
||||
|
||||
```
|
||||
def recordsTotal = Employee.count()
|
||||
println "employee recordsTotal $recordsTotal"
|
||||
```
|
||||
|
||||
Next, apply the filter to the Employee instances to get the count of filtered results, which will always be less than or equal to the total number (again, this is for the pagination code):
|
||||
|
||||
```
|
||||
def c = Employee.createCriteria()
|
||||
def recordsFiltered = c.count {
|
||||
filterer.delegate = delegate
|
||||
filterer()
|
||||
}
|
||||
println "employee recordsFiltered $recordsFiltered"
|
||||
|
||||
```
|
||||
|
||||
Once you have those two counts, you can get the actual filtered instances using the pagination and ordering information as well.
|
||||
|
||||
```
|
||||
def orderer = Employee.withCriteria {
|
||||
filterer.delegate = delegate
|
||||
filterer()
|
||||
orderList.each { oi ->
|
||||
switch (oi[0]) {
|
||||
case 'surname': order 'surname', oi[1]; break
|
||||
case 'givenNames': order 'givenNames', oi[1]; break
|
||||
case 'position': order 'p.name', oi[1]; break
|
||||
case 'office': order 'o.name', oi[1]; break
|
||||
case 'extension': order 'extension', oi[1]; break
|
||||
case 'hired': order 'hired', oi[1]; break
|
||||
case 'salary': order 'salary', oi[1]; break
|
||||
}
|
||||
}
|
||||
maxResults (jqdtParams.length as Integer)
|
||||
firstResult (jqdtParams.start as Integer)
|
||||
}
|
||||
```
|
||||
|
||||
To be completely clear, the pagination code in JTables manages three counts: the total number of records in the data set, the number resulting after the filters are applied, and the number to be displayed on the page (whether the display is scrolling or paginated). The ordering is applied to all the filtered records and the pagination is applied to chunks of those filtered records for display purposes.
|
||||
|
||||
Next, process the results returned by the orderer, creating links to the Employee, Position, and Office instance in each row so the user can click on these links to get all the detail on the relevant instance:
|
||||
|
||||
```
|
||||
def dollarFormatter = new DecimalFormat('$##,###.##')
|
||||
def employees = orderer.collect { employee ->
|
||||
['surname': "<a href='${createLink(controller: 'employee', action: 'show', id: employee.id)}'>${employee.surname}</a>",
|
||||
'givenNames': employee.givenNames,
|
||||
'position': "<a href='${createLink(controller: 'position', action: 'show', id: employee.position?.id)}'>${employee.position?.name}</a>",
|
||||
'office': "<a href='${createLink(controller: 'office', action: 'show', id: employee.office?.id)}'>${employee.office?.name}</a>",
|
||||
'extension': employee.extension,
|
||||
'hired': employee.hired.format('yyyy/MM/dd'),
|
||||
'salary': dollarFormatter.format(employee.salary)]
|
||||
}
|
||||
```
|
||||
|
||||
And finally, create the result you want to return and give it back as JSON, which is what jQuery DataTables requires.
|
||||
|
||||
```
|
||||
def result = [draw: jqdtParams.draw, recordsTotal: recordsTotal, recordsFiltered: recordsFiltered, data: employees]
|
||||
render(result as JSON)
|
||||
}
|
||||
```
|
||||
|
||||
That’s it.
|
||||
|
||||
If you’re familiar with Grails, this probably seems like more work than you might have originally thought, but there’s no rocket science here, just a lot of moving parts. However, if you haven’t had much exposure to Grails (or to Groovy), there’s a lot of new stuff to understand—closures, delegates, and builders, among other things.
|
||||
|
||||
In that case, where to start? The best place is to learn about Groovy itself, especially [Groovy closures][18] and [Groovy delegates and builders][19]. Then go back to the reading suggested above on Grails and Hibernate criteria queries.
|
||||
|
||||
### Conclusions
|
||||
|
||||
jQuery DataTables make awesome tabular data browsers for Grails. Coding the view isn’t too tricky, but the PHP examples provided in the DataTables documentation take you only so far. In particular, they aren’t written with Grails programmers in mind, nor do they explore the finer details of using elements that are references to other classes (essentially lookup tables).
|
||||
|
||||
I’ve used this approach to make a couple of data browsers that allow the user to select which columns to view and accumulate record counts, or just to browse the data. The performance is good even in million-row tables on a relatively modest VPS.
|
||||
|
||||
One caveat: I have stumbled upon some problems with the various Hibernate criteria mechanisms exposed in Grails (see my other GitHub repositories), so care and experimentation is required. If all else fails, the alternative approach is to build SQL strings on the fly and execute them instead. As of this writing, I prefer to work with Grails criteria, unless I get into messy subqueries, but that may just reflect my relative lack of experience with subqueries in Hibernate.
|
||||
|
||||
I hope you Grails programmers out there find this interesting. Please feel free to leave comments or suggestions below.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/18/9/using-grails-jquery-and-datatables
|
||||
|
||||
作者：[Chris Hermansen][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/clhermansen
|
||||
[1]: https://grails.org/
|
||||
[2]: https://jquery.com/
|
||||
[3]: https://datatables.net/
|
||||
[4]: http://php.net/
|
||||
[5]: http://groovy-lang.org/
|
||||
[6]: https://github.com/monetschemist/grails-datatables
|
||||
[7]: https://www.vim.org/
|
||||
[8]: http://openjdk.java.net/
|
||||
[9]: http://sdkman.io/
|
||||
[10]: http://guides.grails.org/creating-your-first-grails-app/guide/index.html
|
||||
[11]: https://opensource.com/file/410061
|
||||
[12]: https://opensource.com/sites/default/files/uploads/screen_1.png (Embrow home screen)
|
||||
[13]: https://opensource.com/file/410066
|
||||
[14]: https://opensource.com/sites/default/files/uploads/screen_2.png (Office list screenshot)
|
||||
[15]: https://opensource.com/file/410071
|
||||
[16]: https://opensource.com/sites/default/files/uploads/screen3.png (Employee controller screenshot)
|
||||
[17]: https://gsp.grails.org/latest/ref/Tags/createLink.html
|
||||
[18]: http://groovy-lang.org/closures.html
|
||||
[19]: http://groovy-lang.org/dsls.html
|
||||
@ -0,0 +1,99 @@
|
||||
What containers can teach us about DevOps
|
||||
======
|
||||
|
||||
The use of containers supports the three pillars of DevOps practices: flow, feedback, and continual experimentation and learning.
|
||||
|
||||
|
||||
|
||||
One can argue that containers and DevOps were made for one another. Certainly, the container ecosystem benefits from the skyrocketing popularity of DevOps practices, both in design choices and in DevOps’ use by teams developing container technologies. Because of this parallel evolution, the use of containers in production can teach teams the fundamentals of DevOps and its three pillars: [The Three Ways][1].
|
||||
|
||||
### Principles of flow
|
||||
|
||||
**Container flow**
|
||||
|
||||
A container can be seen as a silo, and from inside, it is easy to forget the rest of the system: the host node, the cluster, the underlying infrastructure. Inside the container, it might appear that everything is functioning in an acceptable manner. From the outside perspective, though, the application inside the container is a part of a larger ecosystem of applications that make up a service: the web API, the web app user interface, the database, the workers, and caching services and garbage collectors. Teams put constraints on the container to limit performance impact on infrastructure, and much has been done to provide metrics for measuring container performance because overloaded or slow container workloads have downstream impact on other services or customers.
|
||||
|
||||
**Real-world flow**
|
||||
|
||||
This lesson can be applied to teams functioning in a silo as well. Every process (be it code release, infrastructure creation or even, say, manufacturing of [Spacely’s Sprockets][2]), follows a linear path from conception to realization. In technology, this progress flows from development to testing to operations and release. If a team working alone becomes a bottleneck or introduces a problem, the impact is felt all along the entire pipeline. A defect passed down the line destroys productivity downstream. While the broken process within the scope of the team itself may seem perfectly correct, it has a negative impact on the environment as a whole.
|
||||
|
||||
**DevOps and flow**
|
||||
|
||||
The first way of DevOps, principles of flow, is about approaching the process as a whole, striving to comprehend how the system works together and understanding the impact of issues on the entire process. To increase the efficiency of the process, pain points and waste are identified and removed. This is an ongoing process; teams must continually strive to increase visibility into the process and find and fix trouble spots and waste.
|
||||
|
||||
> “The outcomes of putting the First Way into practice include never passing a known defect to downstream work centers, never allowing local optimization to create global degradation, always seeking to increase flow, and always seeking to achieve a profound understanding of the system (as per Deming).”
|
||||
|
||||
–Gene Kim, [The Three Ways: The Principles Underpinning DevOps][3], IT Revolution, 25 Apr. 2017
|
||||
|
||||
### Principles of feedback
|
||||
|
||||
**Container feedback**
|
||||
|
||||
In addition to limiting containers to prevent impact elsewhere, many products have been created to monitor and trend container metrics in an effort to understand what they are doing and notify when they are misbehaving. [Prometheus][4], for example, is [all the rage][5] for collecting metrics from containers and clusters. Containers are excellent at separating applications and providing a way to ship an environment together with the code, sometimes at the cost of opacity, so much is done to try to provide rapid feedback so issues can be addressed promptly within the silo.
|
||||
|
||||
**Real-world feedback**
|
||||
|
||||
The same is necessary for the flow of the system. From inception to realization, an efficient process quickly provides relevant feedback to identify when there is an issue. The key words here are “quick” and “relevant.” Burying teams in thousands of irrelevant notifications make it difficult or even impossible to notice important events that need immediate action, and receiving even relevant information too late may allow small, easily solved issues to move downstream and become bigger problems. Imagine [if Lucy and Ethel][6] had provided immediate feedback that the conveyor belt was too fast—there would have been no problem with the chocolate production (though that would not have been nearly as funny).
|
||||
|
||||
**DevOps and feedback**
|
||||
|
||||
The Second Way of DevOps, principles of feedback, is all about getting relevant information quickly. With immediate, useful feedback, problems can be identified as they happen and addressed before impact is felt elsewhere in the development process. DevOps teams strive to “optimize for downstream” and immediately move to fix problems that might impact other teams that come after them. As with flow, feedback is a continual process to identify ways to quickly get important data and act on problems as they occur.
|
||||
|
||||
> “Creating fast feedback is critical to achieving quality, reliability, and safety in the technology value stream.”
|
||||
|
||||
–Gene Kim, et al., The DevOps Handbook: How to Create World-Class Agility, Reliability, and Security in Technology Organizations, IT Revolution Press, 2016
|
||||
|
||||
### Principles of continual experimentation and learning
|
||||
|
||||
**Container continual experimentation and learning**
|
||||
|
||||
It is a bit more challenging applying operational learning to the Third Way of DevOps:continual experimentation and learning. Trying to salvage what we can grasp of the very edges of the metaphor, containers make development easy, allowing developers and operations teams to test new code or configurations locally and safely outside of production and incorporate discovered benefits into production in a way that was difficult in the past. Changes can be radical and still version-controlled, documented, and shared quickly and easily.
|
||||
|
||||
**Real-world continual experimentation and learning**
|
||||
|
||||
For example, consider this anecdote from my own experience: Years ago, as a young, inexperienced sysadmin (just three weeks into the job), I was asked to make changes to an Apache virtual host running the website of the central IT department for a university. Without an easy-to-use test environment, I made a configuration change to the production site that I thought would accomplish the task and pushed it out. Within a few minutes, I overheard coworkers in the next cube:
|
||||
|
||||
“Wait, is the website down?”
|
||||
|
||||
“Hrm, yeah, it looks like it. What the heck?”
|
||||
|
||||
There was much eye-rolling involved.
|
||||
|
||||
Mortified (the shame is real, folks), I sunk down as far as I could into my seat and furiously tried to back out the changes I’d introduced. Later that same afternoon, the director of the department—the boss of my boss’s boss—appeared in my cube to talk about what had happened. “Don’t worry,” she told me. “We’re not mad at you. It was a mistake and now you have learned.”
|
||||
|
||||
In the world of containers, this could have been easily changed and tested on my own laptop and the broken configuration identified by more skilled team members long before it ever made it into production.
|
||||
|
||||
**DevOps continual experimentation and learning**
|
||||
|
||||
A real culture of experimentation promotes the individual’s ability to find where a change in the process may be beneficial, and to test that assumption without the fear of retaliation if they fail. For DevOps teams, failure becomes an educational tool that adds to the knowledge of the individual and organization, rather than something to be feared or punished. Individuals in the DevOps team dedicate themselves to continuous learning, which in turn benefits the team and wider organization as that knowledge is shared.
|
||||
|
||||
As the metaphor completely falls apart, focus needs to be given to a specific point: The other two principles may appear at first glance to focus entirely on process, but continual learning is a human task—important for the future of the project, the person, the team, and the organization. It has an impact on the process, but it also has an impact on the individual and other people.
|
||||
|
||||
> “Experimentation and risk-taking are what enable us to relentlessly improve our system of work, which often requires us to do things very differently than how we’ve done it for decades.”
|
||||
|
||||
–Gene Kim, et al., [The Phoenix Project: A Novel about IT, DevOps, and Helping Your Business Win][7], IT Revolution Press, 2013
|
||||
|
||||
### Containers can teach us DevOps
|
||||
|
||||
Learning to work effectively with containers can help teach DevOps and the Three Ways: principles of flow, principles of feedback, and principles of continuous experimentation and learning. Looking holistically at the application and infrastructure rather than putting on blinders to everything outside the container teaches us to take all parts of the system and understand their upstream and downstream impacts, break out of silos, and work as a team to increase global performance and deep understanding of the entire system. Working to provide timely and accurate feedback teaches us to create effective feedback patterns within our organizations to identify problems before their impact grows. Finally, providing a safe environment to try new ideas and learn from them teaches us to create a culture where failure represents a positive addition to our knowledge and the ability to take big chances with educated guesses can result in new, elegant solutions to complex problems.
|
||||
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/18/9/containers-can-teach-us-devops
|
||||
|
||||
作者：[Chris Hermansen][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/clhermansen
|
||||
[1]: https://itrevolution.com/the-three-ways-principles-underpinning-devops/
|
||||
[2]: https://en.wikipedia.org/wiki/The_Jetsons
|
||||
[3]: http://itrevolution.com/the-three-ways-principles-underpinning-devops
|
||||
[4]: https://prometheus.io/
|
||||
[5]: https://opensource.com/article/18/9/prometheus-operational-advantage
|
||||
[6]: https://www.youtube.com/watch?v=8NPzLBSBzPI
|
||||
[7]: https://itrevolution.com/book/the-phoenix-project/
|
||||
@ -1,152 +0,0 @@
|
||||
"组"在 Linux 上到底是怎么工作的?
|
||||
============================================================
|
||||
|
||||
|
||||
你好！就在上周，我还自认为对 Linux 上的用户和组的工作机制了如指掌。我认为它们的关系是这样的：
|
||||
|
||||
1. 每个进程都属于一个用户( 比如用户`julia`)
|
||||
|
||||
2. 当这个进程试图读取一个被某个组所拥有的文件时， Linux 会 a）先检查用户`julia` 是否有权限访问文件。(LCTT译注：检查文件的所有者是否就是`julia`) b）检查`julia` 属于哪些组，并进一步检查在这些组里是否有某个组拥有这个文件或者有权限访问这个文件。
|
||||
|
||||
3. 如果上述a,b任一为真（ 或者`其他`位设为有权限访问）,那么这个进程就有权限访问这个文件。
|
||||
|
||||
比如说，如果一个进程被用户`julia`拥有并且`julia` 在`awesome`组，那么这个进程就能访问下面这个文件。
|
||||
|
||||
```
|
||||
r--r--r-- 1 root awesome 6872 Sep 24 11:09 file.txt
|
||||
|
||||
```
|
||||
|
||||
然而上述的机制我并没有考虑得非常清楚，如果你硬要我阐述清楚，我会说进程可能会在**运行时**去检查`/etc/group` 文件里是否有某些组拥有当前的用户。
|
||||
|
||||
### 然而这并不是Linux 里“组”的工作机制
|
||||
|
||||
我在上个星期的工作中发现了一件有趣的事，事实证明我前面的理解错了，我对组的工作机制的描述并不准确。特别是Linux**并不会**在进程每次试图访问一个文件时就去检查这个进程的用户属于哪些组。
|
||||
|
||||
我在读了[The Linux Programming
|
||||
Interface][1]这本书的第九章后才恍然大悟（这本书真是太棒了。）这才是组真正的工作方式！我意识到之前我并没有真正理解用户和组是怎么工作的，我信心满满的尝试了下面的内容并且验证到底发生了什么，事实证明现在我的理解才是对的。
|
||||
|
||||
### 用户和组权限检查是怎么完成的
|
||||
|
||||
现在这些关键的知识在我看来非常简单! 这本书的第九章上来就告诉我如下事实：用户和组ID是**进程的属性**，它们是：
|
||||
|
||||
* 真实用户ID和组ID；
|
||||
|
||||
* 有效用户ID和组ID；
|
||||
|
||||
* 被保存的set-user-ID和被保存的set-group-ID;
|
||||
|
||||
* 文件系统用户ID和组ID（特定于 Linux);
|
||||
|
||||
* 增补的组ID；
|
||||
|
||||
这说明Linux**实际上**检查一个进程能否访问一个文件所做的组检查是这样的：
|
||||
|
||||
* 检查一个进程的组ID和补充组ID（这些ID就在进程的属性里，**并不是**实时在`/etc/group`里查找这些ID）
|
||||
|
||||
* 检查要访问的文件的访问属性里的组设置
|
||||
|
||||
|
||||
* 确定进程对文件是否有权限访问（LCTT 译注：即文件的组是否是以上的组之一）
|
||||
|
||||
通常当访问控制的时候使用的是**有效**用户/组ID，而不是**真实**用户/组ID。技术上来说当访问一个文件时使用的是**文件系统**ID,他们实际上和有效用户/组ID一样。（LCTT译注：这句话针对 Linux 而言。）
|
||||
|
||||
### 将一个用户加入一个组并不会将一个已存在的进程（的用户）加入那个组
|
||||
|
||||
下面是一个有趣的例子：如果我创建了一个新的组:`panda` 组并且将我自己(bork)加入到这个组，然后运行`groups` 来检查我是否在这个组里：结果是我（bork）竟然不在这个组？！
|
||||
|
||||
|
||||
```
|
||||
bork@kiwi~> sudo addgroup panda
|
||||
Adding group `panda' (GID 1001) ...
|
||||
Done.
|
||||
bork@kiwi~> sudo adduser bork panda
|
||||
Adding user `bork' to group `panda' ...
|
||||
Adding user bork to group panda
|
||||
Done.
|
||||
bork@kiwi~> groups
|
||||
bork adm cdrom sudo dip plugdev lpadmin sambashare docker lxd
|
||||
|
||||
```
|
||||
|
||||
`panda`并不在上面的组里！为了再次确定我们的发现，让我们建一个文件，这个文件被`panda`组拥有，看看我能否访问它。
|
||||
|
||||
|
||||
```
|
||||
$ touch panda-file.txt
|
||||
$ sudo chown root:panda panda-file.txt
|
||||
$ sudo chmod 660 panda-file.txt
|
||||
$ cat panda-file.txt
|
||||
cat: panda-file.txt: Permission denied
|
||||
|
||||
```
|
||||
|
||||
好吧，确定了，我(bork)无法访问`panda-file.txt`。这一点都不让人吃惊,我的命令解释器并没有`panda` 组作为补充组ID，运行`adduser bork panda`并不会改变这一点。
|
||||
|
||||
|
||||
### 那进程一开始是怎么得到用户的组的呢？
|
||||
|
||||
|
||||
这真是个非常令人困惑的问题，对吗？如果进程会将组的信息预置到进程的属性里面，进程在初始化的时候怎么取到组的呢？很明显你无法给你自己指定更多的组（否则就会和Linux访问控制的初衷相违背了。。。）
|
||||
|
||||
有一点还是很清楚的：一个新的进程是怎么从我的命令行解释器（/bash/fish）里被**执行**而得到它的组的。（新的）进程将拥有我的用户 ID（bork），并且进程属性里还有很多组ID。从我的命令解释器里执行的所有进程是从这个命令解释器里`复刻`而来的，所以这个新进程得到了和命令解释器同样的组。
|
||||
|
||||
因此一定存在一个“第一个”进程来把你的组设置到进程属性里，而所有由此进程而衍生的进程将都设置这些组。而那个“第一个”进程就是你的**登录命令**,在我的笔记本电脑上，它是由‘登录’程序(`/bin/login`)实例化而来。` 登录程序` 以root身份运行,然后调用了一个 C 的库函数-`initgroups`来设置你的进程的组（具体来说是通过读取`/etc/group` 文件）,因为登录程序是以root运行的，所以它能设置你的进程的组。
|
||||
|
||||
|
||||
### 让我们再登录一次
|
||||
|
||||
好了！既然我们的`login shell`正在运行,而我又想刷新我的进程的组设置，从我们前面所学到的进程是怎么初始化组ID的，我应该可以通过再次运行`login` 程序来刷新我的进程组并启动一个新的`login shell`！
|
||||
|
||||
让我们试试下边的方法:
|
||||
|
||||
```
|
||||
$ sudo login bork
|
||||
$ groups
|
||||
bork adm cdrom sudo dip plugdev lpadmin sambashare docker lxd panda
|
||||
$ cat panda-file.txt # it works! I can access the file owned by `panda` now!
|
||||
|
||||
```
|
||||
|
||||
当然，成功了！现在由登录程序衍生的程序的用户是组`panda`的一部分了！太棒了！这并不会影响我其他的已经在运行的登录程序（及其子进程），如果我真的希望“所有的”进程都能对`panda`
|
||||
组有访问权限。我必须完全的重启我的登陆会话，这意味着我必须退出我的窗口管理器然后再重新`login`。(LCTT译注：即更新进程树的树根进程，这里是窗口管理器进程。)
|
||||
|
||||
### newgrp命令
|
||||
|
||||
|
||||
在 Twitter 上有人告诉我如果只是想启动一个刷新了组信息的命令解释器的话，你可以使用`newgrp`（LCTT译注：不启动新的命令解释器）,如下：
|
||||
|
||||
```
|
||||
sudo addgroup panda
|
||||
sudo adduser bork panda
|
||||
newgrp panda # starts a new shell, and you don't have to be root to run it!
|
||||
|
||||
```
|
||||
|
||||
|
||||
你也可以用`sg panda bash` 来完成同样的效果，这个命令能启动一个`bash` 登录程序，而这个程序就有`panda` 组。
|
||||
|
||||
### seduid 将设置有效用户 ID
|
||||
|
||||
其实我一直对一个进程如何以`setuid root`的权限来运行意味着什么有点似是而非。现在我知道了，事实上所发生的是：setuid 设置了`有效用户ID`! 如果我（'julia'）运行了一个`setuid root` 的进程（ 比如`passwd`）,那么进程的**真实**用户 ID 将为`julia`,而**有效**用户 ID 将被设置为`root`。
|
||||
|
||||
`passwd` 需要以root权限来运行，但是它能看到进程的真实用户ID是`julia` ,是`julia`启动了这个进程，`passwd`会阻止这个进程修改除了`julia`之外的用户密码。
|
||||
|
||||
### 就是这些了！
|
||||
|
||||
在 Linux Programming Interface 这本书里有很多Linux上一些功能的罕见使用方法以及Linux上所有的事物到底是怎么运行的详细解释，这里我就不一一展开了。那本书棒极了，我上面所说的都在该书的第九章，这章在1300页的书里只占了17页。
|
||||
|
||||
我最爱这本书的一点是我只用读17页关于用户和组是怎么工作的内容，而这区区17页就能做到内容完备，详实有用。我不用读完所有的1300页书就能得到有用的东西，太棒了！
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://jvns.ca/blog/2017/11/20/groups/
|
||||
|
||||
作者：[Julia Evans ][a]
|
||||
译者：[DavidChen](https://github.com/DavidChenLiang)
|
||||
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://jvns.ca/
|
||||
[1]:http://man7.org/tlpi/
|
||||
@ -0,0 +1,173 @@
|
||||
一种具有语法高亮和 Git 集成的 Cat 克隆命令——Bat
|
||||
======
|
||||
|
||||
|
||||
|
||||
在类UNIX系统中，我们使用 **‘cat’** 命令去打印和连接文件。使用cat命令, 我们能将文件目录打印到到标准输出，合成几个文件为一个目标文件，还有追加几个文件到目标文件中。今天，我偶然发现一个具有相似作用的命令叫做 **“Bat”** ，一个 cat 命令的克隆版，具有一些例如语法高亮、 git 集成和自动分页等非常酷的特性。在这个简略指南中，我们将讲述如何在 linux 中安装和使用 Bat 命令。
|
||||
|
||||
### 安装
|
||||
|
||||
Bat 可以在 Arch Linux 的默认软件源中获取。 所以你可以使用 pacman 命令在任何 arch-based 的系统上来安装它。
|
||||
```
|
||||
$ sudo pacman -S bat
|
||||
|
||||
```
|
||||
|
||||
在 Debian,Ubuntu, Linux Mint 等系统中，从[**发布页面**][1] 下载 **.deb** 文件，然后用下面的命令来安装。
|
||||
```
|
||||
$ sudo apt install gdebi
|
||||
|
||||
$ sudo gdebi bat_0.5.0_amd64.deb
|
||||
|
||||
```
|
||||
|
||||
对于其他系统，你也许需要从软件源编译并安装 确保你已经安装了 Rust 1.26 或者更高版本。
|
||||
|
||||
|
||||
|
||||
然后运行以下命令来安装 Bat
|
||||
```
|
||||
$ cargo install bat
|
||||
|
||||
```
|
||||
|
||||
或者，你可以从 [**Linuxbrew**][2] 软件包管理中来安装它。
|
||||
```
|
||||
$ brew install bat
|
||||
|
||||
```
|
||||
|
||||
### Bat 命令的使用
|
||||
|
||||
Bat 命令的使用与 cat 命令的使用非常相似。
|
||||
|
||||
使用 Bat 命令创建一个新的文件:
|
||||
```
|
||||
$ bat > file.txt
|
||||
|
||||
```
|
||||
|
||||
使用 Bat 命令来查看文件内容，只需要:
|
||||
```
|
||||
$ bat file.txt
|
||||
|
||||
```
|
||||
|
||||
你能同时查看多个文件，通过:
|
||||
```
|
||||
$ bat file1.txt file2.txt
|
||||
|
||||
```
|
||||
|
||||
将多个文件的内容合并至一个单独文件中:
|
||||
```
|
||||
$ bat file1.txt file2.txt file3.txt > document.txt
|
||||
|
||||
```
|
||||
|
||||
就像我之前提到的那样，除了浏览和编辑文件以外， Bat 命令有一些非常酷的特性。
|
||||
|
||||
Bat 命令支持大多数编程和标记语言的<ruby>语法高亮<rt>syntax highlighting</rt></ruby>。比如，下面这个例子。我将使用 cat 和 bat 命令来展示 **reverse.py** 的内容。
|
||||
|
||||
|
||||
|
||||
你注意到区别了吗？ cat 命令以纯文本格式显示文件的内容，而 bat 命令显示了语法高亮和整齐的文本对齐格式。更好了不是吗？
|
||||
|
||||
如果你只想显示行号（而不是文本对齐）使用
|
||||
**-n** 标记。
|
||||
```
|
||||
$ bat -n reverse.py
|
||||
|
||||
```
|
||||
|
||||
**Sample output:**
|
||||
|
||||
|
||||
另一个 Bat 命令中值得注意的特性是它支持<ruby>自动分页<rt>automatic paging</rt></ruby>。 它的意思是当文件的输出对于屏幕来说太大的时候，bat 命令自动将自己的输出内容传输到 **less** 命令中，所以你可以一页一页的查看输出内容。
|
||||
|
||||
让我给你看一个例子，使用cat命令查看跨多个页面的文件的内容时，提示快速跳至文件的最后一页，你看不到内容的开头和中间部分。
|
||||
|
||||
看一下下面的输出：
|
||||
|
||||
|
||||
|
||||
正如你所看到的，cat 命令显示了文章的最后一页。
|
||||
|
||||
所以你也许需要去将使用 cat 命令的输出传输到 **less** 命令中去从开头一页一页的查看内容。
|
||||
```
|
||||
$ cat reverse.py | less
|
||||
|
||||
```
|
||||
|
||||
现在你可以使用 ENTER 键去一页一页的查看输出。然而当你使用 bat 命令时这些都是不必要的。bat命令将自动传输跨越多个页面的文件的输出。
|
||||
|
||||
```
|
||||
$ bat reverse.py
|
||||
|
||||
```
|
||||
|
||||
**Sample output:**
|
||||
|
||||
|
||||
|
||||
现在按下 ENTER 键去往下一页。
|
||||
|
||||
bat 命令也支持 <ruby>Git 集成<rt>**GIT integration**</rt></ruby>，
|
||||
这样您就可以轻松查看/编辑Git存储库中的文件。 它与 Git 连接可以显示关于索引的修改。（看左栏）
|
||||
|
||||
|
||||
|
||||
**定制 Bat**
|
||||
|
||||
如果你不喜欢默认主题，你也可以修改它。Bat 同样有修改它的选项。
|
||||
|
||||
若要显示可用主题，只需运行：
|
||||
```
|
||||
$ bat --list-themes
|
||||
1337
|
||||
DarkNeon
|
||||
Default
|
||||
GitHub
|
||||
Monokai Extended
|
||||
Monokai Extended Bright
|
||||
Monokai Extended Light
|
||||
Monokai Extended Origin
|
||||
TwoDark
|
||||
|
||||
```
|
||||
|
||||
|
||||
要使用其他主题，例如 TwoDark，请运行：
|
||||
```
|
||||
$ bat --theme=TwoDark file.txt
|
||||
|
||||
```
|
||||
|
||||
如果你想永久改变主题，在你的 shells startup 文件中加入 `export BAT_THEME="TwoDark"`。
|
||||
|
||||
|
||||
Bat还可以选择修改输出的外观。使用 `--style` 选项来修改输出外观。仅显示 Git 的更改和行号但不显示网格和文件头，请使用 `--style=numbers,changes`.
|
||||
|
||||
|
||||
更多详细信息，请参阅 Bat 项目的 GitHub 库（链接在文末）
|
||||
|
||||
最好，这就是目前的全部内容了。希望这篇文章会帮到你。更多精彩文章即将到来，敬请关注！
|
||||
|
||||
干杯！
|
||||
|
||||
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.ostechnix.com/bat-a-cat-clone-with-syntax-highlighting-and-git-integration/
|
||||
|
||||
作者：[SK][a]
|
||||
选题：[lujun9972](https://github.com/lujun9972)
|
||||
译者：[z52527](https://github.com/z52527)
|
||||
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/
|
||||
[1]:https://github.com/sharkdp/bat/releases
|
||||
[2]:https://www.ostechnix.com/linuxbrew-common-package-manager-linux-mac-os-x/
|
||||
Loading…
Reference in New Issue
Block a user