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@ -1,17 +1,21 @@
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如何在Linux的终端测试网速
|
||||
======
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||||
学习如何在Linux终端使用命令行工具测试网速,或者仅用一条python命令立刻获得网速的测试结果。
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||||
|
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> 学习如何在 Linux 终端使用命令行工具 `speedtest` 测试网速，或者仅用一条 python 命令立刻获得网速的测试结果。
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||||
|
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![在Linux终端测试网速][1]
|
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|
||||
我们都会在连接网络或者wifi的时候去测试网络带宽。 为什么不用我们自己的服务器！下面将会教你如何在Linux终端测试网速。
|
||||
我们都会在连接到一个新的网络或者 WIFI 的时候去测试网络带宽。 为什么不用我们自己的服务器！下面将会教你如何在 Linux 终端测试网速。
|
||||
|
||||
我们多数都会使用[Mb/s][2]标准来测试网速。 仅仅只是桌面上的一个简单的操作，访问他们的网站点击浏览。
|
||||
它将使用最近的服务器来扫描你的本地主机来测试网速。 如果你使用的是移动设备，他们有对应的移动端APP。但如果你使用的是只有命令行终端界面的则会有些不同。下面让我们一起看看如何在Linux的终端来测试网速。
|
||||
如果你只是想偶尔的做一次网速测试而不想去下载测试工具,那么请往下看如何使用命令完成测试。
|
||||
我们多数都会使用 [Ookla 的 Speedtest][2] 来测试网速。 这在桌面上是很简单的操作，访问他们的网站点击“Go”浏览即可。它将使用最近的服务器来扫描你的本地主机来测试网速。 如果你使用的是移动设备，他们有对应的移动端 APP。但如果你使用的是只有命令行终端，界面的则会有些不同。下面让我们一起看看如何在Linux的终端来测试网速。
|
||||
|
||||
如果你只是想偶尔的做一次网速测试而不想去下载测试工具，那么请往下看如何使用命令完成测试。
|
||||
|
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### 第一步：下载网速测试命令行工具。
|
||||
|
||||
首先，你需要从github上下载网速测试命令行工具。现在，上面也包含许多其他的Linu相关的仓库，如果已经在你的库中，你可以直接在你的Linux上进行安装。 让我们继续下载和安装过程，安装的git包取决于你的Linux发行版。然后按照下面的方法来克隆Github speedtest存储库
|
||||
首先，你需要从 [GitHub][3] 上下载 `speedtest` 命令行工具。现在，它也被包含在许多其它的 Linux 仓库中，如果已经在你的库中，你可以直接[在你的 Linux 发行版上进行安装][4]。
|
||||
|
||||
让我们继续下载和安装过程，安装的 git 包取决于你的 Linux 发行版。然后按照下面的方法来克隆 Github speedtest 存储库
|
||||
|
||||
```
|
||||
[root@kerneltalks ~]# git clone https://github.com/sivel/speedtest-cli.git
|
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@ -20,10 +24,9 @@ remote: Counting objects: 913, done.
|
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remote: Total 913 (delta 0), reused 0 (delta 0), pack-reused 913
|
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Receiving objects: 100% (913/913), 251.31 KiB | 143.00 KiB/s, done.
|
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Resolving deltas: 100% (518/518), done.
|
||||
|
||||
```
|
||||
|
||||
它将会被克隆到你当前的工作目录，新的名为speedtest-cli的目录将会被创建,你将在新的目录下看到如下的文件。
|
||||
它将会被克隆到你当前的工作目录，新的名为 `speedtest-cli` 的目录将会被创建，你将在新的目录下看到如下的文件。
|
||||
|
||||
```
|
||||
[root@kerneltalks ~]# cd speedtest-cli
|
||||
@ -41,11 +44,13 @@ total 96
|
||||
-rw-r--r--. 1 root root 333 Oct 7 16:55 tox.ini
|
||||
```
|
||||
|
||||
名为speedtest.py的脚本文件就是用来测试网速的。你可以在/usr/bin执行环境下将这个脚本链接到一条命令以便这台机器上的所有用户都能使用。或者你可以为这个脚本创建一个命令别名这样就能让所有用户很容易使用它。
|
||||
名为 `speedtest.py` 的 Python 脚本文件就是用来测试网速的。
|
||||
|
||||
### 运行python脚本
|
||||
你可以将这个脚本链接到 `/usr/bin` 下，以便这台机器上的所有用户都能使用。或者你可以为这个脚本创建一个[命令别名][5]，这样就能让所有用户很容易使用它。
|
||||
|
||||
现在，直接运行这个脚本，不需要添加任何参数它将会搜寻最近的服务器来测试你的网速。
|
||||
### 运行 Python 脚本
|
||||
|
||||
现在，直接运行这个脚本，不需要添加任何参数，它将会搜寻最近的服务器来测试你的网速。
|
||||
|
||||
```
|
||||
[root@kerneltalks speedtest-cli]# python speedtest.py
|
||||
@ -60,13 +65,13 @@ Testing upload speed............................................................
|
||||
Upload: 323.95 Mbit/s
|
||||
```
|
||||
|
||||
Oh！ 不要被这个网速惊讶道。😀我在AWE EX2的服务器上。那是亚马逊数据中心的网速！🙂
|
||||
Oh！ 不要被这个网速惊讶道。我在 AWE EX2 的服务器上。那是亚马逊数据中心的网速！
|
||||
|
||||
### 这个脚本可以添加有不同的选项。
|
||||
|
||||
下面的几个选项对这个脚本可能会很有用处：
|
||||
|
||||
** 用搜寻你附近的网路测试服务器，使用 --list和grep加上本地名来列出所有附件的服务器。
|
||||
**要搜寻你附近的网路测试服务器**，使用 `--list` 和 `grep` 加上地名来列出所有附近的服务器。
|
||||
|
||||
```
|
||||
[root@kerneltalks speedtest-cli]# python speedtest.py --list | grep -i mumbai
|
||||
@ -86,8 +91,9 @@ Oh！ 不要被这个网速惊讶道。😀我在AWE EX2的服务器上。那是
|
||||
|
||||
然后你就能从搜寻结果中看到，第一列是服务器识别号，紧接着是公司的名称和所在地，最后是离你的距离。
|
||||
|
||||
** 如果要使用指定的服务器来测试网速，后面跟上命令 --server 加上服务器的识别号。
|
||||
|
||||
**如果要使用指定的服务器来测试网速**，后面跟上 `--server` 加上服务器的识别号。
|
||||
|
||||
```
|
||||
[root@kerneltalks speedtest-cli]# python speedtest.py --server 2827
|
||||
Retrieving speedtest.net configuration...
|
||||
Testing from Amazon (35.154.184.126)...
|
||||
@ -100,7 +106,7 @@ Testing upload speed............................................................
|
||||
Upload: 69.25 Mbit/s
|
||||
```
|
||||
|
||||
** 如果想得到你的测试结果的共享链接，使用命令 --share,你将会得到测试结果的链接。
|
||||
**如果想得到你的测试结果的分享链接**，使用 `--share`，你将会得到测试结果的链接。
|
||||
|
||||
```
|
||||
[root@kerneltalks speedtest-cli]# python speedtest.py --share
|
||||
@ -114,22 +120,22 @@ Download: 621.00 Mbit/s
|
||||
Testing upload speed................................................................................................
|
||||
Upload: 367.37 Mbit/s
|
||||
Share results: http://www.speedtest.net/result/6687428141.png
|
||||
|
||||
```
|
||||
|
||||
输出中的最后一行就是你的测试结果的链接。下载下来的图片内容如下 :
|
||||
|
||||
![Speedtest result on Linux][7]
|
||||
|
||||
这就是全部的过程！如果你不想子结果中看到这些技术术语，你也可以使用如下的命令迅速测出你的网速
|
||||
这就是全部的过程！如果你不想了解这些技术细节，你也可以使用如下的一行命令迅速测出你的网速。
|
||||
|
||||
### 要想在终端使用一条命令测试网速。
|
||||
|
||||
我们将使用Curl工具来在线抓取上面使用的python脚本然后直接用python执行脚本
|
||||
我们将使用 `curl` 工具来在线抓取上面使用的 Python 脚本然后直接用 Python 执行脚本。
|
||||
|
||||
```
|
||||
[root@kerneltalks ~]# curl -s https://raw.githubusercontent.com/sivel/speedtest-cli/master/speedtest.py | python -
|
||||
```
|
||||
|
||||
上面的脚本将会运行脚本输出结果到屏幕上。
|
||||
|
||||
```
|
||||
@ -145,22 +151,24 @@ Testing upload speed............................................................
|
||||
Upload: 355.84 Mbit/s
|
||||
```
|
||||
|
||||
这是在 RHEL 7 上执行的结果，在 Ubuntu、Debian、Fedora 或者 CentOS 上一样可以执行。
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
这是在RHEL 7上执行的结果，在Ubuntu,Debian, Fedora或者Centos上一样可以执行。
|
||||
via: https://kerneltalks.com/tips-tricks/how-to-test-internet-speed-in-linux-terminal/
|
||||
|
||||
作者：[Shrikant Lavhate][a]
|
||||
译者：[FelixYFZ ](https://github.com/FelixYFZ)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
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://kerneltalks.com
|
||||
[1]:https://c1.kerneltalks.com/wp-content/uploads/2017/10/check-internet-speed-from-Linux.png
|
||||
[1]:https://a1.kerneltalks.com/wp-content/uploads/2017/10/check-internet-speed-from-Linux.png
|
||||
[2]:http://www.speedtest.net/
|
||||
[3]:https://github.com/sivel/speedtest-cli
|
||||
[4]:https://kerneltalks.com/tools/package-installation-linux-yum-apt/
|
||||
[5]:https://kerneltalks.com/commands/command-alias-in-linux-unix/
|
||||
[6]:https://kerneltalks.com/howto/install-ec2-linux-server-aws-with-screenshots/
|
||||
[7]:https://c3.kerneltalks.com/wp-content/uploads/2017/10/speedtest-on-linux.png
|
||||
[7]:https://a3.kerneltalks.com/wp-content/uploads/2017/10/speedtest-on-linux.png
|
||||
[8]:https://kerneltalks.com/tips-tricks/4-tools-download-file-using-command-line-linux/
|
||||
@ -1,14 +1,17 @@
|
||||
11 个超棒的 vi 技巧和窍门
|
||||
11 个超棒的 Vi 技巧和窍门
|
||||
======
|
||||
|
||||
> 是否你刚刚接触 Vi 还是想进阶，这些技巧可以很快让你成为高级用户。
|
||||
|
||||
|
||||
|
||||
[vi][1] 编辑器是 Linux 最流行的编辑器之一，默认安装在 Unix 和类 Uinux 系统中。无论您是 vi 新手还是想进修，这些技巧都对您有用。
|
||||
[Vi][1] 编辑器是 Unix 和像 Linux 这样的类 Unix 系统中 Linux 最流行的编辑器之一。无论您是 vi 新手还是想进阶，这里有 11 个技巧可以增强你使用的方式。
|
||||
|
||||
### 编辑
|
||||
|
||||
编辑长文本时可能很难受，特别是编辑其中某一行时，需要移动许久才能到这行。这有个很快的方法：
|
||||
|
||||
1. `:set number` 这个命令可是在编辑器左边显示行号。
|
||||
1、 `:set number` 这个命令可是在编辑器左边显示行号。
|
||||
|
||||
|
||||
|
||||
@ -18,20 +21,21 @@
|
||||
|
||||
### 快速导航
|
||||
|
||||
2. `i` 将工作方式从“命令模式”更改为“输入模式”，并在当前光标位置开始插入内容。
|
||||
3. `a` 除了是光标之后开始插入年内容，与上面的效果是一样的。
|
||||
4. `o` 在光标的下一行位置开始插入内容。
|
||||
2、 `i` 将工作方式从“命令模式”更改为“输入模式”，并在当前光标位置开始插入内容。
|
||||
|
||||
3、 `a` 除了是光标之后开始插入内容，与上面的效果是一样的。
|
||||
|
||||
4、 `o` 在光标的下一行位置开始插入内容。
|
||||
|
||||
### 删除
|
||||
|
||||
如果您发现错误或错别字，能快速的修正是很重要的。好在 vi 都事先想好了。
|
||||
如果您发现错误或错别字，能快速的修正是很重要的。好在 Vi 都事先想好了。
|
||||
|
||||
了解 vi 的删除功能，保证你不会意外按下某个键并永久删除一行或多段内容，这点至关重要。
|
||||
了解 Vi 的删除功能，保证你不会意外按下某个键并永久删除一行或多段内容，这点至关重要。
|
||||
|
||||
5. `x` 删除当前光标的字符。
|
||||
6. `dd` 删除当前行 （是的，整行内容！)
|
||||
5、 `x` 删除当前光标的字符。
|
||||
|
||||
6、 `dd` 删除当前行 （是的，整行内容！)
|
||||
|
||||
下面看可怕的部分：`30dd` 从当前行开始删除以下 30 行！使用此命令请慎重。
|
||||
|
||||
@ -39,16 +43,15 @@
|
||||
|
||||
您可以在“命令模式”搜索关键字，而不用在大量文本内容中手动导航查找特定的单词或内容。
|
||||
|
||||
7. `:/<keyword>` 搜索 `< >` 中的单词并将光标移动到第一个匹配项。
|
||||
8. 导航到该单词的下一个匹配项，请输入 `n` 并继续按下， 直到找到您要找的内容。
|
||||
7、 `:/<keyword>` 搜索 `< >` 中的单词并将光标移动到第一个匹配项。
|
||||
|
||||
8、 导航到该单词的下一个匹配项，请输入 `n` 并继续按下， 直到找到您要找的内容。
|
||||
|
||||
|
||||
例如，在这个图像中我要搜索包含 `ssh` 的内容， vi 光标就会突出第一个结果的开始位置。
|
||||
例如，在这个图像中我要搜索包含 `ssh` 的内容， Vi 光标就会突出第一个结果的开始位置。
|
||||
|
||||
|
||||
|
||||
按下 n 之后， vi 光标就会突出下一个匹配项。
|
||||
按下 `n` 之后， Vi 光标就会突出下一个匹配项。
|
||||
|
||||
|
||||
|
||||
@ -56,29 +59,26 @@
|
||||
|
||||
开发人员 （或其他人） 可能会发现这个命令很有用。
|
||||
|
||||
9. `:x` 保存您的工作空间并退出 vi 。
|
||||
9、 `:x` 保存您的工作并退出 Vi 。
|
||||
|
||||
|
||||
|
||||
10. 如果你想实时保存，那么这有个更快的方法。你可以按下 `Shift+q` （或者大写字母 Q ) 来进入 [Ex 模式][2] , 而不是在键盘上按 `Shift+:` 。但是如果你只是想按下 `x` 来保存退出，那就没有什么区别（如上所示）。
|
||||
|
||||
|
||||
10、 如果你想节省哪怕是纳秒，那么这有个更快的回到终端的方法。不用在键盘上按 `Shift+:` ，而是按下 `Shift+q` （或者大写字母 Q ) 来进入 [Ex 模式][2] 。但是如果你只是想按下 `x` 来保存退出，那就没有什么区别（如上所示）。
|
||||
|
||||
### 替换
|
||||
|
||||
如果您想将文中的某个单词全部替换为一个单词，这有个很巧妙的招式。例如，如果您想在一个大文件中将 "desktop" 替换为 "laptop" ，那么单调的搜索每个出现的 "desktop" 将其删掉，然后再输入 "laotop" ，是很浪费时间的。
|
||||
如果您想将文中的某个单词全部替换为一个单词，这有个很巧妙的招式。例如，如果您想在一个大文件中将 “desktop” 替换为 “laptop” ，那么单调的搜索每个出现的 “desktop” 将其删掉，然后再输入 “laotop” ，是很浪费时间的。
|
||||
|
||||
11. `:%s/desktop/laptop/g` 这个命令将在整个文件中的 "desktop" 用 "laptop" 替换，他就像 Linux 的 `sed` 命令一样。
|
||||
11、 `:%s/desktop/laptop/g` 这个命令将在整个文件中的 “desktop” 用 “laptop” 替换，他就像 Linux 的 `sed` 命令一样。
|
||||
|
||||
|
||||
|
||||
这个例子中我用 "user" 替换了 "root" ：
|
||||
这个例子中我用 “user” 替换了 “root” ：
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
这些技巧应该能帮组任何想开始学 vi 的人。我有遗漏其他巧妙的提示吗？请在评论中分享他们。
|
||||
这些技巧应该能帮组任何想开始学 Vi 的人。我有遗漏其他巧妙的提示吗？请在评论中分享他们。
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
@ -86,7 +86,7 @@ via: https://opensource.com/article/18/1/top-11-vi-tips-and-tricks
|
||||
|
||||
作者：[Archit Modi][a]
|
||||
译者：[MZqk](https://github.com/MZqk)
|
||||
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
|
||||
|
||||
71
published/20180215 What is a Linux -oops.md
Normal file
71
published/20180215 What is a Linux -oops.md
Normal file
@ -0,0 +1,71 @@
|
||||
什么是 Linux “oops”？
|
||||
======
|
||||
> Linux 内核正在盯着你，当它检测到系统上运行的某些东西违反了正常内核行为时，它会关闭系统并发出一个“oops”！
|
||||
|
||||
|
||||
|
||||
如果你检查你的 Linux 系统上运行的进程，你可能会对一个叫做 “kerneloops” 的进程感到好奇。提示一下，它是 “kernel oops”，而不是 “kerne loops”。
|
||||
|
||||
坦率地说，“oops” 是 Linux 内核的一部分出现了偏差行为。你有做错了什么吗？可能没有。但有一些不对劲。而那个做了错事的进程可能已经被 CPU 结束。最糟糕的是，内核可能会报错并突然关闭系统。
|
||||
|
||||
请注意，“oops” 不是首字母缩略词。它不代表像“<ruby>面向对象的编程和系统<rt>object-oriented programming and systems</rt></ruby>” 或“<ruby>超出程序规范<rt>out of procedural specs</rt></ruby>” 之类的东西。它实际上就是“哎呀” （oops），就像你刚掉下一杯酒或踩在你的猫身上。哎呀！ “oops” 的复数是 “oopses”。
|
||||
|
||||
oops 意味着系统上运行的某些东西违反了内核有关正确行为的规则。也许代码尝试采取不允许的代码路径或使用无效指针。不管它是什么，内核 —— 总是在监测进程的错误行为 —— 很可能会阻止特定进程，并将它做了什么的消息写入控制台、 `/var/log/dmesg` 或 `/var/log/kern.log` 中。
|
||||
|
||||
oops 可能是由内核本身引起的，也可能是某些进程试图让内核违反在系统上能做的事以及它们被允许做的事。
|
||||
|
||||
oops 将生成一个<ruby>崩溃签名<rt>crash signature</rt></ruby>，这可以帮助内核开发人员找出错误并提高代码质量。
|
||||
|
||||
系统上运行的 kerneloops 进程可能如下所示：
|
||||
|
||||
```
|
||||
kernoops 881 1 0 Feb11 ? 00:00:01 /usr/sbin/kerneloops
|
||||
```
|
||||
|
||||
你可能会注意到该进程不是由 root 运行的，而是由名为 “kernoops” 的用户运行的，并且它的运行时间极少。实际上，分配给这个特定用户的唯一任务是运行 kerneloops。
|
||||
|
||||
```
|
||||
$ sudo grep kernoops /etc/passwd
|
||||
kernoops:x:113:65534:Kernel Oops Tracking Daemon,,,:/:/bin/false
|
||||
```
|
||||
|
||||
如果你的 Linux 系统不带有 kerneloops（比如 Debian），你可以考虑添加它。查看这个 [Debian 页面][1]了解更多信息。
|
||||
|
||||
### 什么时候应该关注 oops？
|
||||
|
||||
一般 oops 没什么大不了的。它在一定程度上取决于特定进程所扮演的角色。它也取决于 oops 的类别。
|
||||
|
||||
有些 oops 很严重，会导致<ruby>系统恐慌<rt>system panic</rt></ruby>。从技术上讲，系统恐慌是 oops 的一个子集（即更严重的 oops）。当内核检测到的问题足够严重以至于内核认为它（内核）必须立即停止运行以防止数据丢失或对系统造成其他损害时会出现。因此，系统需要暂停并重新启动，以防止任何不一致导致不可用或不可靠。所以系统恐慌实际上是为了保护自己免受不可挽回的损害。
|
||||
|
||||
总之，所有的内核恐慌都是 oops，但并不是所有的 oops 都是内核恐慌。
|
||||
|
||||
`/var/log/kern.log` 和相关的轮转日志（`/var/log/kern.log.1`、`/var/log/kern.log.2` 等）包含由内核生成并由 syslog 处理的日志。
|
||||
|
||||
kerneloops 程序收集并默认将错误信息提交到 <http://oops.kernel.org/>，在那里它会被分析并呈现给内核开发者。此进程的配置详细信息在 `/etc/kerneloops.conf` 文件中指定。你可以使用下面的命令轻松查看设置：
|
||||
|
||||
```
|
||||
$ sudo cat /etc/kerneloops.conf | grep -v ^# | grep -v ^$
|
||||
[sudo] password for shs:
|
||||
allow-submit = ask
|
||||
allow-pass-on = yes
|
||||
submit-url = http://oops.kernel.org/submitoops.php
|
||||
log-file = /var/log/kern.log
|
||||
submit-pipe = /usr/share/apport/kernel_oops
|
||||
```
|
||||
|
||||
在上面的（默认）设置中，内核问题可以被提交，但要求用户获得许可。如果设置为 `allow-submit = always`，则不会询问用户。
|
||||
|
||||
调试内核问题是使用 Linux 系统的更高级技巧之一。幸运的是，大多数 Linux 用户很少或从没有经历过 oops 或内核恐慌。不过，知道 kerneloops 这样的进程在系统中执行什么操作，了解可能会报告什么以及系统何时遇到严重的内核冲突也是很好的。
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.networkworld.com/article/3254778/linux/what-is-a-linux-oops.html
|
||||
|
||||
作者：[Sandra Henry-Stocker][a]
|
||||
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://www.networkworld.com/author/Sandra-Henry_Stocker/
|
||||
[1]:https://packages.debian.org/stretch/kerneloops
|
||||
@ -0,0 +1,212 @@
|
||||
Linux 系统中 sudo 命令的 10 个技巧
|
||||
======
|
||||
|
||||
![Linux-sudo-command-tips][1]
|
||||
|
||||
### 概览
|
||||
|
||||
`sudo` 表示 “**s**uper**u**ser **do**”。 它允许已验证的用户以其他用户的身份来运行命令。其他用户可以是普通用户或者超级用户。然而，大部分时候我们用它来以提升的权限来运行命令。
|
||||
|
||||
`sudo` 命令与安全策略配合使用，默认安全策略是 `sudoers`，可以通过文件 `/etc/sudoers` 来配置。其安全策略具有高度可拓展性。人们可以开发和分发他们自己的安全策略作为插件。
|
||||
|
||||
### 与 su 的区别
|
||||
|
||||
在 GNU/Linux 中，有两种方式可以用提升的权限来运行命令：
|
||||
|
||||
* 使用 `su` 命令
|
||||
* 使用 `sudo` 命令
|
||||
|
||||
`su` 表示 “**s**witch **u**ser”。使用 `su`，我们可以切换到 root 用户并且执行命令。但是这种方式存在一些缺点：
|
||||
|
||||
* 我们需要与他人共享 root 的密码。
|
||||
* 因为 root 用户为超级用户，我们不能授予受控的访问权限。
|
||||
* 我们无法审查用户在做什么。
|
||||
|
||||
`sudo` 以独特的方式解决了这些问题。
|
||||
|
||||
1. 首先，我们不需要妥协来分享 root 用户的密码。普通用户使用他们自己的密码就可以用提升的权限来执行命令。
|
||||
2. 我们可以控制 `sudo` 用户的访问，这意味着我们可以限制用户只执行某些命令。
|
||||
3. 除此之外，`sudo` 用户的所有活动都会被记录下来，因此我们可以随时审查进行了哪些操作。在基于 Debian 的 GNU/Linux 中，所有活动都记录在 `/var/log/auth.log` 文件中。
|
||||
|
||||
本教程后面的部分阐述了这些要点。
|
||||
|
||||
### 实际动手操作 sudo
|
||||
|
||||
现在，我们对 sudo 有了大致的了解。让我们实际动手操作吧。为了演示，我使用 Ubuntu。但是，其它发行版本的操作应该是相同的。
|
||||
|
||||
#### 允许 sudo 权限
|
||||
|
||||
让我们添加普通用户为 `sudo` 用户吧。在我的情形中，用户名为 `linuxtechi`。
|
||||
|
||||
1) 按如下所示编辑 `/etc/sudoers` 文件：
|
||||
|
||||
```
|
||||
$ sudo visudo
|
||||
```
|
||||
|
||||
2) 添加以下行来允许用户 `linuxtechi` 有 sudo 权限：
|
||||
|
||||
```
|
||||
linuxtechi ALL=(ALL) ALL
|
||||
```
|
||||
|
||||
上述命令中：
|
||||
|
||||
* `linuxtechi` 表示用户名
|
||||
* 第一个 `ALL` 指示允许从任何终端、机器访问 `sudo`
|
||||
* 第二个 `(ALL)` 指示 `sudo` 命令被允许以任何用户身份执行
|
||||
* 第三个 `ALL` 表示所有命令都可以作为 root 执行
|
||||
|
||||
|
||||
#### 以提升的权限执行命令
|
||||
|
||||
要用提升的权限执行命令，只需要在命令前加上 `sudo`，如下所示：
|
||||
|
||||
```
|
||||
$ sudo cat /etc/passwd
|
||||
```
|
||||
|
||||
当你执行这个命令时，它会询问 `linuxtechi` 的密码，而不是 root 用户的密码。
|
||||
|
||||
#### 以其他用户执行命令
|
||||
|
||||
除此之外，我们可以使用 `sudo` 以另一个用户身份执行命令。例如，在下面的命令中，用户 `linuxtechi` 以用户 `devesh` 的身份执行命令：
|
||||
|
||||
```
|
||||
$ sudo -u devesh whoami
|
||||
[sudo] password for linuxtechi:
|
||||
devesh
|
||||
```
|
||||
|
||||
#### 内置命令行为
|
||||
|
||||
`sudo` 的一个限制是 —— 它无法使用 Shell 的内置命令。例如， `history` 记录是内置命令，如果你试图用 `sudo` 执行这个命令，那么会提示如下的未找到命令的错误：
|
||||
|
||||
```
|
||||
$ sudo history
|
||||
[sudo] password for linuxtechi:
|
||||
sudo: history: command not found
|
||||
|
||||
```
|
||||
|
||||
**访问 root shell**
|
||||
|
||||
为了克服上述问题，我们可以访问 root shell，并在那里执行任何命令，包括 Shell 的内置命令。
|
||||
|
||||
要访问 root shell, 执行下面的命令:
|
||||
|
||||
```
|
||||
$ sudo bash
|
||||
```
|
||||
|
||||
执行完这个命令后——您将观察到提示符变为井号（`#`）。
|
||||
|
||||
### 技巧
|
||||
|
||||
这节我们将讨论一些有用的技巧，这将有助于提高生产力。大多数命令可用于完成日常任务。
|
||||
|
||||
#### 以 sudo 用户执行之前的命令
|
||||
|
||||
让我们假设你想用提升的权限执行之前的命令，那么下面的技巧将会很有用：
|
||||
|
||||
```
|
||||
$ sudo !4
|
||||
```
|
||||
|
||||
上面的命令将使用提升的权限执行历史记录中的第 4 条命令。
|
||||
|
||||
#### 在 Vim 里面使用 sudo 命令
|
||||
|
||||
很多时候，我们编辑系统的配置文件时，在保存时才意识到我们需要 root 访问权限来执行此操作。因为这个可能让我们丢失我们对文件的改动。没有必要惊慌，我们可以在 Vim 中使用下面的命令来解决这种情况：
|
||||
|
||||
```
|
||||
:w !sudo tee %
|
||||
```
|
||||
|
||||
上述命令中：
|
||||
|
||||
* 冒号 (`:`) 表明我们处于 Vim 的退出模式
|
||||
* 感叹号 (`!`) 表明我们正在运行 shell 命令
|
||||
* `sudo` 和 `tee` 都是 shell 命令
|
||||
* 百分号 (`%`) 表明从当前行开始的所有行
|
||||
|
||||
|
||||
|
||||
#### 使用 sudo 执行多个命令
|
||||
|
||||
至今我们用 `sudo` 只执行了单个命令，但我们可以用它执行多个命令。只需要用分号 (`;`) 隔开命令，如下所示：
|
||||
|
||||
```
|
||||
$ sudo -- bash -c 'pwd; hostname; whoami'
|
||||
|
||||
```
|
||||
|
||||
上述命令中
|
||||
|
||||
* 双连字符 (`--`) 停止命令行切换
|
||||
* `bash` 表示要用于执行命令的 shell 名称
|
||||
* `-c` 选项后面跟着要执行的命令
|
||||
|
||||
|
||||
|
||||
#### 无密码运行 sudo 命令
|
||||
|
||||
当第一次执行 `sudo` 命令时，它会提示输入密码，默认情形下密码被缓存 15 分钟。但是，我们可以避免这个操作，并使用 `NOPASSWD` 关键字禁用密码认证，如下所示：
|
||||
|
||||
```
|
||||
linuxtechi ALL=(ALL) NOPASSWD: ALL
|
||||
```
|
||||
|
||||
#### 限制用户执行某些命令
|
||||
|
||||
为了提供受控访问，我们可以限制 `sudo` 用户只执行某些命令。例如，下面的行只允许执行 `echo` 和 `ls` 命令 。
|
||||
|
||||
```
|
||||
linuxtechi ALL=(ALL) NOPASSWD: /bin/echo /bin/ls
|
||||
```
|
||||
|
||||
#### 深入了解 sudo
|
||||
|
||||
让我们进一步深入了解 `sudo` 命令。
|
||||
|
||||
```
|
||||
$ ls -l /usr/bin/sudo
|
||||
-rwsr-xr-x 1 root root 145040 Jun 13 2017 /usr/bin/sudo
|
||||
```
|
||||
|
||||
如果仔细观察文件权限，则发现 `sudo` 上启用了 setuid 位。当任何用户运行这个二进制文件时，它将以拥有该文件的用户权限运行。在所示情形下，它是 root 用户。
|
||||
|
||||
|
||||
为了演示这一点，我们可以使用 `id` 命令，如下所示：
|
||||
|
||||
```
|
||||
$ id
|
||||
uid=1002(linuxtechi) gid=1002(linuxtechi) groups=1002(linuxtechi)
|
||||
```
|
||||
|
||||
当我们不使用 `sudo` 执行 `id` 命令时，将显示用户 `linuxtechi` 的 id。
|
||||
|
||||
```
|
||||
$ sudo id
|
||||
uid=0(root) gid=0(root) groups=0(root)
|
||||
|
||||
```
|
||||
|
||||
但是，如果我们使用 `sudo` 执行 `id` 命令时，则会显示 root 用户的 id。
|
||||
|
||||
### 结论
|
||||
|
||||
从这篇文章可以看出 —— `sudo` 为普通用户提供了更多受控访问。使用这些技术，多用户可以用安全的方式与 GNU/Linux 进行交互。
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.linuxtechi.com/quick-tips-sudo-command-linux-systems/
|
||||
|
||||
作者：[Pradeep Kumar][a]
|
||||
译者：[szcf-weiya](https://github.com/szcf-weiya)
|
||||
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.linuxtechi.com/author/pradeep/
|
||||
[1]:https://www.linuxtechi.com/wp-content/uploads/2018/03/Linux-sudo-command-tips.jpg
|
||||
@ -0,0 +1,117 @@
|
||||
# Is DevOps compatible with part-time community teams?
|
||||
|
||||
### DevOps can greatly benefit projects of all sizes. Here's how to build a DevOps adoption plan for smaller projects.
|
||||
|
||||
|
||||
|
||||
Image by :
|
||||
|
||||
[WOCinTech Chat][1]. Modified by Opensource.com. [CC BY-SA 4.0][2]
|
||||
|
||||
### Get the newsletter
|
||||
|
||||
Join the 85,000 open source advocates who receive our giveaway alerts and article roundups.
|
||||
|
||||
DevOps seems to be the talk of the IT world of late—and for good reason. DevOps has streamlined the process and production of IT development and operations. However, there is also an upfront cost to embracing a DevOps ideology, in terms of time, effort, knowledge, and financial investment. Larger companies may have the bandwidth, budget, and time to make the necessary changes, but is it feasible for part-time, resource-strapped communities?
|
||||
|
||||
Part-time communities are teams of like-minded people who take on projects outside of their normal work schedules. The members of these communities are driven by passion and a shared purpose. For instance, one such community is the [ALM | DevOps Rangers][3]. With 100 rangers engaged across the globe, a DevOps solution may seem daunting; nonetheless, they took on the challenge and embraced the ideology. Through their example, we've learned that DevOps is not only feasible but desirable in smaller teams. To read about their transformation, check out [How DevOps eliminates development bottlenecks][4].
|
||||
|
||||
> “DevOps is the union of people, process, and products to enable continuous delivery of value to our end customers.” - Donovan Brown
|
||||
|
||||
### The cost of DevOps
|
||||
|
||||
As stated above, there is an _upfront_ "cost" to DevOps. The cost manifests itself in many forms, such as the time and collaboration between development, operations, and other stakeholders, planning a smooth-flowing process that delivers continuous value, finding the best DevOps products, and training the team in new technologies, to name a few. This aligns directly with Donovan's definition of DevOps, in fact—a **process** for delivering **continuous value** and the **people** who make that happen.
|
||||
|
||||
More DevOps resources
|
||||
|
||||
* [What is DevOps?][5]
|
||||
* [Free eBook: DevOps with OpenShift][6]
|
||||
* [10 bad DevOps habits to break][7]
|
||||
* [10 must-read DevOps resources][8]
|
||||
* [The latest on DevOps][9]
|
||||
|
||||
Streamlined DevOps takes a lot of planning and training just to create the process, and that doesn't even consider the testing phase. We also can't forget the existing in-flight projects that need to be converted into the new system. While the cost increases the more pervasive the transformation—for instance, if an organization aims to unify its entire development organization under a single process, then that would cost more versus transforming a single pilot or subset of the entire portfolio—these upfront costs must be addressed regardless of their scale. There are a lot of resources and products already out there that can be implemented for a smoother transition—but again, we face the time and effort that will be necessary just to research which ones might work best.
|
||||
|
||||
In the case of the ALM | DevOps Rangers, they had to halt all projects for a couple of sprints to set up the initial process. Many organizations would not be able to do that. Even part-time groups might have very good reasons to keep things moving, which only adds to the complexity. In such scenarios, additional cutover planning (and therefore additional cost) is needed, and the overall state of the community is one of flux and change, which adds risk, which—you guessed it—requires more cost to mitigate.
|
||||
|
||||
There is also an _ongoing_ "cost" that teams will face with a DevOps mindset: Simple maintenance of the system, training and transitioning new team members, and keeping up with new, improved technologies are all a part of the process.
|
||||
|
||||
### DevOps for a part-time community
|
||||
|
||||
Whereas larger companies can dedicate a single manager or even a team to the task over overseeing the continuous integration and continuous deployment (CI/CD) pipelines, part-time community teams don't have the bandwidth to give. With such a massive undertaking we must ask: Is it even worth it for groups with fewer resources to take on DevOps for their community? Or should they abandon the idea of DevOps altogether?
|
||||
|
||||
The answer to that is dependent on a few variables, such as the ability of the teams to be self-managing, the time and effort each member is willing to put into the transformation, and the dedication of the community to the process.
|
||||
|
||||
### Example: Benefits of DevOps in a part-time community
|
||||
|
||||
Luckily, we aren't without examples to demonstrate just how DevOps can benefit a smaller group. Let's take a quick look at the ALM Rangers again. The results from their transformation help us understand how DevOps changed their community:
|
||||
|
||||
|
||||
|
||||
As illustrated, there are some huge benefits for part-time community teams. Planning goes from long, arduous design sessions to a quick prototyping and storyboarding process. Builds become automated, reliable, and resilient. Testing and bug detection are proactive instead of reactive, which turns into a happier clientele. Multiple full-time program managers are replaced with self-managing teams with a single part-time manager to oversee projects. Teams become smaller and more efficient, which equates to higher production rates and higher-quality project delivery. With results like these, it's hard to argue against DevOps.
|
||||
|
||||
Still, the upfront and ongoing costs aren't right for every community. The number-one most important aspect of any DevOps transformation is the mindset of the people involved. Adopting the idea of self-managing teams who work in autonomy instead of the traditional chain-of-command scheme can be a challenge for any group. The members must be willing to work independently without a lot of oversight and take ownership of their features and user experience, but at the same time, work in a setting that is fully transparent to the rest of the community. **The success or failure of a DevOps strategy lies on the team.**
|
||||
|
||||
### Making the DevOps transition in 4 steps
|
||||
|
||||
Another important question to ask: How can a low-bandwidth group make such a massive transition? The good news is that a DevOps transformation doesn’t need to happen all at once. Taken in smaller, more manageable steps, organizations of any size can embrace DevOps.
|
||||
|
||||
1. Determine why DevOps may be the solution you need. Are your projects bottlenecking? Are they running over budget and over time? Of course, these concerns are common for any community, big or small. Answering these questions leads us to step two:
|
||||
2. Develop the right framework to improve the engineering process. DevOps is all about automation, collaboration, and streamlining. Rather than trying to fit everyone into the same process box, the framework should support the work habits, preferences, and delivery needs of the community. Some broad standards should be established (for example, that all teams use a particular version control system). Beyond that, however, let the teams decide their own best process.
|
||||
3. Use the current products that are already available if they meet your needs. Why reinvent the wheel?
|
||||
4. Finally, implement and test the actual DevOps solution. This is, of course, where the actual value of DevOps is realized. There will likely be a few issues and some heartburn, but it will all be worth it in the end because, once established, the products of the community’s work will be nimbler and faster for the users.
|
||||
|
||||
### Reuse DevOps solutions
|
||||
|
||||
One benefit to creating effective CI/CD pipelines is the reusability of those pipelines. Although there is no one-size fits all solution, anyone can adopt a process. There are several pre-made templates available for you to examine, such as build templates on VSTS, ARM templates to deploy Azure resources, and "cookbook"-style textbooks from technical publishers. Once it identifies a process that works well, a community can also create its own template by defining and establishing standards and making that template easily discoverable by the entire community. For more information on DevOps journeys and tools, check out [this site][10].
|
||||
|
||||
### Summary
|
||||
|
||||
Overall, the success or failure of DevOps relies on the culture of a community. It doesn't matter if the community is a large, resource-rich enterprise or a small, resource-sparse, part-time group. DevOps will still bring solid benefits. The difference is in the approach for adoption and the scale of that adoption. There are both upfront and ongoing costs, but the value greatly outweighs those costs. Communities can use any of the powerful tools available today for their pipelines, and they can also leverage reusability, such as templates, to reduce upfront implementation costs. DevOps is most certainly feasible—and even critical—for the success of part-time community teams.
|
||||
|
||||
---
|
||||
|
||||
**\[See our related story, [How DevOps eliminates development bottlenecks][11].\]**
|
||||
|
||||
|
||||
### About the author
|
||||
|
||||
[][13]
|
||||
|
||||
Edward Fry \- Edward a business technophile who revels in blending people, process, and technology to solve real problems with grace and efficiency. As a member of the ALM Rangers, he loves to share his passion for the process of software development and ways to get computers to do the drudge work so that people can dream the big dreams. He also enjoys the art of great software design and architecture and also just likes being immersed in code. When he isn't helping people with technology, he enjoys... [more about Edward Fry][14]
|
||||
|
||||
[More about me][15]
|
||||
|
||||
* [Learn how you can contribute][16]
|
||||
|
||||
---
|
||||
|
||||
via: [https://opensource.com/article/18/4/devops-compatible-part-time-community-teams][17]
|
||||
|
||||
作者: [Edward Fry][18] 选题者: [@lujun9972][19] 译者: [译者ID][20] 校对: [校对者ID][21]
|
||||
|
||||
本文由 [LCTT][22] 原创编译，[Linux中国][23] 荣誉推出
|
||||
|
||||
[1]: https://www.flickr.com/photos/wocintechchat/25392377053/
|
||||
[2]: https://creativecommons.org/licenses/by/4.0/
|
||||
[3]: https://github.com/ALM-Rangers
|
||||
[4]: https://opensource.com/article/17/11/devops-rangers-transformation
|
||||
[5]: https://opensource.com/resources/devops?src=devops_resource_menu1
|
||||
[6]: https://www.openshift.com/promotions/devops-with-openshift.html?intcmp=7016000000127cYAAQ&src=devops_resource_menu2
|
||||
[7]: https://enterprisersproject.com/article/2018/1/10-bad-devops-habits-break?intcmp=7016000000127cYAAQ&src=devops_resource_menu3
|
||||
[8]: https://opensource.com/article/17/12/10-must-read-devops-books?src=devops_resource_menu4
|
||||
[9]: https://opensource.com/tags/devops?src=devops_resource_menu5
|
||||
[10]: https://www.visualstudio.com/devops/
|
||||
[11]: https://opensource.com/article/17/11/devops-rangers-transformation
|
||||
[12]: https://opensource.com/tags/devops
|
||||
[13]: https://opensource.com/users/edwardf
|
||||
[14]: https://opensource.com/users/edwardf
|
||||
[15]: https://opensource.com/users/edwardf
|
||||
[16]: https://opensource.com/participate
|
||||
[17]: https://opensource.com/article/18/4/devops-compatible-part-time-community-teams
|
||||
[18]: https://opensource.com/users/edwardf
|
||||
[19]: https://github.com/lujun9972
|
||||
[20]: https://github.com/译者ID
|
||||
[21]: https://github.com/校对者ID
|
||||
[22]: https://github.com/LCTT/TranslateProject
|
||||
[23]: https://linux.cn/
|
||||
@ -1,157 +0,0 @@
|
||||
Download YouTube Videos in Linux Command Line
|
||||
======
|
||||
**Brief: Easily download YouTube videos in Linux using youtube-dl command line tool. With this tool, you can also choose video format and video quality such as 1080p or 4K.**
|
||||
|
||||
|
||||
|
||||
I know you have already seen [how to download YouTube videos][1]. But those tools were mostly GUI ways. I am going to show you how to download YouTube videos in Linux terminal using youtube-dl.
|
||||
|
||||
### Install youtube-dl to download YouTube videos in Linux terminal
|
||||
|
||||
[youtube-dl][2] is a Python-based small command-line tool that allows downloading videos from [YouTube][3], [Dailymotion][4], Photobucket, Facebook, Yahoo, Metacafe, Depositfiles and few more similar sites. It is written in pygtk and requires Python interpreter to run this program, it’s not platform restricted. It should run on any Unix, Windows or in Mac OS X based systems.
|
||||
|
||||
The youtube-dl tool supports resuming interrupted downloads. If youtube-dl is killed (for example by Ctrl-C or due to loss of Internet connectivity) in the middle of the download, you can simply re-run it with the same YouTube video URL. It will automatically resume the unfinished download, as long as a partial download is present in the current directory. Which means you don’t need [download managers in Linux][5] just for resuming downloads.
|
||||
|
||||
#### youtube-dl features
|
||||
|
||||
This tiny tool has so many features that it won’t be an exaggeration to call it the best YouTube downloader for Linux.
|
||||
|
||||
* Download videos from not only YouTube but other popular video websites like Dailymotion, Facebook etc
|
||||
* Allows downloading videos in several available video formats such as MP4, WebM etc.
|
||||
* You can also choose the quality of the video being downloaded. If the video is available in 4K, you can download it in 4K, 1080p, 720p etc
|
||||
* Automatical pause and resume of video downloads.
|
||||
* Allows to bypass YouTube geo-restrictions
|
||||
|
||||
|
||||
|
||||
Downloading videos from websites could be against their policies. It’s up to you if choose to download videos.
|
||||
|
||||
#### How to install youtube-dl
|
||||
|
||||
youtube-dl is a popular program and is available in the default repositories of most Linux distributions, if not all. You can use the standard way of installing packages in your distribution to install youtube-dl. I’ll still show some commands for the sake of it.
|
||||
|
||||
If you are running Ubuntu-based Linux distribution, you can install it using this command:
|
||||
```
|
||||
sudo apt install youtube-dl
|
||||
|
||||
```
|
||||
|
||||
For other Linux distribution, you can quickly install youtube-dl on your system through the command line interface with:
|
||||
```
|
||||
sudo wget https://yt-dl.org/downloads/latest/youtube-dl -O/usr/local/bin/youtube-dl
|
||||
|
||||
```
|
||||
|
||||
After fetching the file, you need to set a executable permission on the script to execute properly.
|
||||
```
|
||||
sudo chmod a+rx /usr/local/bin/youtube-dl
|
||||
|
||||
```
|
||||
|
||||
#### Using YouTube-dl for downloading videos:
|
||||
|
||||
To download a video file, simply run the following command. Where “VIDEO_URL” is the URL of the video that you want to download.
|
||||
```
|
||||
youtube-dl<video_url>
|
||||
|
||||
```
|
||||
|
||||
#### Download YouTube videos in various formats and quality size
|
||||
|
||||
These days YouTube videos have different resolutions, you first need to check available video formats of a given YouTube video. For that run youtube-dl with “-F” option. It will show you a list of available formats.
|
||||
```
|
||||
youtube-dl -F <video_url>
|
||||
|
||||
```
|
||||
|
||||
Its output will be like:
|
||||
```
|
||||
Setting language
|
||||
BlXaGWbFVKY: Downloading video webpage
|
||||
BlXaGWbFVKY: Downloading video info webpage
|
||||
BlXaGWbFVKY: Extracting video information
|
||||
Available formats:
|
||||
37 : mp4 [1080x1920]
|
||||
46 : webm [1080x1920]
|
||||
22 : mp4 [720x1280]
|
||||
45 : webm [720x1280]
|
||||
35 : flv [480x854]
|
||||
44 : webm [480x854]
|
||||
34 : flv [360x640]
|
||||
18 : mp4 [360x640]
|
||||
43 : webm [360x640]
|
||||
5 : flv [240x400]
|
||||
17 : mp4 [144x176]
|
||||
|
||||
```
|
||||
|
||||
Now among the available video formats, choose one that you like. For example, if you want to download it in MP4 version and 1080 pixel, you should use:
|
||||
```
|
||||
youtube-dl -f 37<video_url>
|
||||
|
||||
```
|
||||
|
||||
#### Download subtitles of videos using youtube-dl
|
||||
|
||||
First, check if there are subtitles available for the video. To list all subs for a video, use the command below:
|
||||
```
|
||||
youtube-dl --list-subs <video_url>
|
||||
|
||||
```
|
||||
|
||||
To download all subs, but not the video:
|
||||
```
|
||||
youtube-dl --all-subs --skip-download <video_url>
|
||||
|
||||
```
|
||||
|
||||
#### Download entire YouTube playlist
|
||||
|
||||
To download a playlist, simply run the following command. Where “playlist_url” is the URL of the playlist that you want to download.
|
||||
```
|
||||
youtube-dl -cit <playlist_url>
|
||||
|
||||
```
|
||||
|
||||
#### Download only audio from YouTube videos
|
||||
|
||||
If you just want to download the audio from a YouTube video, you can use the -x option to simply extract the audio file from the video.
|
||||
```
|
||||
youtube-dl -x <video_url>
|
||||
|
||||
```
|
||||
|
||||
The default file format is Ogg which you may not like. You can specify the file format of the audio file in the following manner:
|
||||
```
|
||||
youtube-dl -x --audio-format mp3 <video_url>
|
||||
|
||||
```
|
||||
|
||||
#### And a lot more can be done with youtube-dl
|
||||
|
||||
youtube-dl is a versatile command line tool and provides a number of functionalities. No wonder it is such a popular command line tool.
|
||||
|
||||
I have only shown some of the most common usages of this tool. But if you want to explore its capabilities further, please check its [manual][6].
|
||||
|
||||
I hope this article helped you to download YouTube videos on Linux. If you have questions or suggestions, please drop a comment below.
|
||||
|
||||
Article updated with inputs from Abhishek Prakash.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://itsfoss.com/download-youtube-linux/
|
||||
|
||||
作者：[alimiracle][a]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
选题：[lujun9972](https://github.com/lujun9972)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:https://itsfoss.com/author/ali/
|
||||
[1]:https://itsfoss.com/download-youtube-videos-ubuntu/
|
||||
[2]:https://rg3.github.io/youtube-dl/
|
||||
[3]:https://www.youtube.com/c/itsfoss/
|
||||
[4]:https://www.dailymotion.com/
|
||||
[5]:https://itsfoss.com/4-best-download-managers-for-linux/
|
||||
[6]:https://github.com/rg3/youtube-dl/blob/master/README.md#readme
|
||||
@ -1,3 +1,5 @@
|
||||
pinewall translating
|
||||
|
||||
Dry – An Interactive CLI Manager For Docker Containers
|
||||
======
|
||||
Docker is a software that allows operating-system-level virtualization also known as containerization.
|
||||
|
||||
@ -1,3 +1,4 @@
|
||||
[ dotcra translating ]
|
||||
The fc Command Tutorial With Examples For Beginners
|
||||
======
|
||||
|
||||
|
||||
@ -1,102 +0,0 @@
|
||||
translating---geekpi
|
||||
|
||||
|
||||
A Kernel Module That Forcibly Shutdown Your System
|
||||
======
|
||||
|
||||
|
||||
I know that staying up late is bad for the health. But, who cares? I have been a night owl for years. I usually go to bed after 12 am, sometimes after 1 am. The next morning, I snooze my alarm at least three times, wake up tired and grumpy. Everyday, I promise myself I will go to bed earlier, but ended up going to bed very late as usual. And, this cycle continues! If you’re anything like me, here is a good news. A fellow late nighter has developed a Kernel module named **“Kgotobed”** that forces you to go to bed at a specific time. That said it will forcibly shutdown your system.
|
||||
|
||||
Why should I use this? I have plenty of other options. I can set a cron job to schedule system shutdown at a specific time. I can set up a reminder or alarm clock. I can use a browser plugin or a software. You might ask! However, they all are can easily be ignored or bypassed. Kgotobed is something that you can’t ignore. Something that **can’t be disabled even if you’re a root user**. Yes, it will forcibly power off your system at the specified time. There is no snooze option. You can’t postpone the power off process or you can’t cancel it either. Your system will go down at the specified time no matter what. You have been warned!!
|
||||
|
||||
### Install Kgotobed
|
||||
|
||||
Make sure you have installed **dkms**. It is available in the default repositories of most Linux distributions.
|
||||
|
||||
For example on Fedora, you can install it using the following command:
|
||||
```
|
||||
$ sudo dnf install kernel-devel-$(uname -r) dkms
|
||||
|
||||
```
|
||||
|
||||
On Debian, Ubuntu, linux Mint:
|
||||
```
|
||||
$ sudo apt install dkms
|
||||
|
||||
```
|
||||
|
||||
Once installed the prerequisites, git clone Kgotobed project.
|
||||
```
|
||||
$ git clone https://github.com/nikital/kgotobed.git
|
||||
|
||||
```
|
||||
|
||||
This command will clone all contents of Kgotobed repository in a folder named “kgotobed” in your current working directory. Cd to that directory:
|
||||
```
|
||||
$ cd kgotobed/
|
||||
|
||||
```
|
||||
|
||||
And, install Kgotobed driver using command:
|
||||
```
|
||||
$ sudo make install
|
||||
|
||||
```
|
||||
|
||||
The above command will register **kgotobed.ko** module with **DKMS** (so that it will be rebuilt for every kernel you run) and Install **gotobed** utility in **/usr/local/bin/** location and then register, enable and start kgotobed service.
|
||||
|
||||
### How it works
|
||||
|
||||
By default, Kgotobed sets bedtime to **1:00 AM**. That said, your computer will shutdown at 1:00 AM no matter what you’re doing.
|
||||
|
||||
To view the current bed time, run:
|
||||
```
|
||||
$ gotobed
|
||||
Current bedtime is 2018-04-10 01:00:00
|
||||
|
||||
```
|
||||
|
||||
To move the bed time earlier, for example 22:00 (10 PM), run:
|
||||
```
|
||||
$ sudo gotobed 22:00
|
||||
[sudo] password for sk:
|
||||
Current bedtime is 2018-04-10 00:58:00
|
||||
Setting bedtime to 2018-04-09 22:00:00
|
||||
Bedtime will be in 2 hours 16 minutes
|
||||
|
||||
```
|
||||
|
||||
This can be helpful when you want to sleep earlier!
|
||||
|
||||
However, you can’t move the bed time later i.e after 1:00 AM. You can’t unload the module, and adjusting system clock won’t help either. The only way out is a reboot!!
|
||||
|
||||
To set different default time, you need to customize **kgotobed.service** (by editing it or by using systemd drop-in).
|
||||
|
||||
### Uninstall Kgotobed
|
||||
|
||||
Not happy with Kgotobed? No worries! Go to the “kgotobed” folder which we cloned earlier and run the following command to uninstall it.
|
||||
```
|
||||
$ sudo make uninstall
|
||||
|
||||
```
|
||||
|
||||
Again, I warn you there is no way to snooze, postpone, or cancel the power off process, even if you’re a root user. Your system will go down forcibly at the specified time. This is not for everyone! It may drive you nuts when you’re working on an important task. In such cases, make sure you have saved the work from time to time or use some advanced utilities that help you to auto shutdown, reboot, suspend, and hibernate your system at a specific time as described in the following link.
|
||||
|
||||
And, that’s for now. Hope you find this guide useful. More good stuffs to come. Stay tuned!
|
||||
|
||||
Cheers!
|
||||
|
||||
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.ostechnix.com/kgotobed-a-kernel-module-that-forcibly-shutdown-your-system/
|
||||
|
||||
作者：[SK][a]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
选题：[lujun9972](https://github.com/lujun9972)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:https://www.ostechnix.com/author/sk/
|
||||
@ -1,3 +1,5 @@
|
||||
translating---geekpi
|
||||
|
||||
The Vrms Program Helps You To Find Non-free Software In Debian
|
||||
======
|
||||
|
||||
|
||||
@ -0,0 +1,138 @@
|
||||
How To Browse Stack Overflow From Terminal
|
||||
======
|
||||
|
||||
|
||||
A while ago, we have written about [**SoCLI**][1], a python script to search and browse Stack Overflow website from command line. Today, we will discuss about a similar tool named **“how2”**. It is a command line utility to browse Stack Overflow from Terminal. You can query in the plain English as the way you do in [**Google search**][2] and it uses Google and Stackoverflow APIs to search for the given queries. It is free and open source utility written using NodeJS.
|
||||
|
||||
### Browse Stack Overflow From Terminal Using how2
|
||||
|
||||
Since how2 is a NodeJS package, we can install it using Npm package manager. If you haven’t installed Npm and NodeJS already, refer the following guide.
|
||||
|
||||
After installing Npm and NodeJS, run the following command to install how2 utility.
|
||||
```
|
||||
$ npm install -g how2
|
||||
|
||||
```
|
||||
|
||||
Now let us see how to browse Stack Overflow uisng this program. The typical usage to search through Stack Overflow site using “how2” utility is:
|
||||
```
|
||||
$ how2 <search-query>
|
||||
|
||||
```
|
||||
|
||||
For example, I am going to search for how to create tgz archive.
|
||||
```
|
||||
$ how2 create archive tgz
|
||||
|
||||
```
|
||||
|
||||
Oops! I get the following error.
|
||||
```
|
||||
/home/sk/.nvm/versions/node/v9.11.1/lib/node_modules/how2/node_modules/devnull/transports/transport.js:59
|
||||
Transport.prototype.__proto__ = EventEmitter.prototype;
|
||||
^
|
||||
|
||||
TypeError: Cannot read property 'prototype' of undefined
|
||||
at Object.<anonymous> (/home/sk/.nvm/versions/node/v9.11.1/lib/node_modules/how2/node_modules/devnull/transports/transport.js:59:46)
|
||||
at Module._compile (internal/modules/cjs/loader.js:654:30)
|
||||
at Object.Module._extensions..js (internal/modules/cjs/loader.js:665:10)
|
||||
at Module.load (internal/modules/cjs/loader.js:566:32)
|
||||
at tryModuleLoad (internal/modules/cjs/loader.js:506:12)
|
||||
at Function.Module._load (internal/modules/cjs/loader.js:498:3)
|
||||
at Module.require (internal/modules/cjs/loader.js:598:17)
|
||||
at require (internal/modules/cjs/helpers.js:11:18)
|
||||
at Object.<anonymous> (/home/sk/.nvm/versions/node/v9.11.1/lib/node_modules/how2/node_modules/devnull/transports/stream.js:8:17)
|
||||
at Module._compile (internal/modules/cjs/loader.js:654:30)
|
||||
|
||||
```
|
||||
|
||||
I may be a bug. I hope it gets fixed in the future versions. However, I find a workaround posted [**here**][3].
|
||||
|
||||
To fix this error temporarily, you need to edit the **transport.js** file using command:
|
||||
```
|
||||
$ vi /home/sk/.nvm/versions/node/v9.11.1/lib/node_modules/how2/node_modules/devnull/transports/transport.js
|
||||
|
||||
```
|
||||
|
||||
The actual path of this file will be displayed in your error output. Replace the above file path with your own. Then find the following line:
|
||||
```
|
||||
var EventEmitter = process.EventEmitter;
|
||||
|
||||
```
|
||||
|
||||
and replace it with following line:
|
||||
```
|
||||
var EventEmitter = require('events');
|
||||
|
||||
```
|
||||
|
||||
Press ESC and type **:wq** to save and quit the file.
|
||||
|
||||
Now search again the query.
|
||||
```
|
||||
$ how2 create archive tgz
|
||||
|
||||
```
|
||||
|
||||
Here is the sample output from my Ubuntu system.
|
||||
|
||||
[![][4]][5]
|
||||
|
||||
If the answer you’re looking for is not displayed in the above output, press **SPACE BAR** key to start the interactive search where you can go through all suggested questions and answers from the Stack Overflow site.
|
||||
|
||||
[![][4]][6]
|
||||
|
||||
Use UP/DOWN arrows to move between the results. Once you got the right answer/question, hit SPACE BAR or ENTER key to open it in the Terminal.
|
||||
|
||||
[![][4]][7]
|
||||
|
||||
To go back and exit, press **ESC**.
|
||||
|
||||
**Search answers for specific language**
|
||||
|
||||
If you don’t specify a language it **defaults to Bash** unix command line and give you immediately the most likely answer as above. You can also narrow the results to a specific language, for example perl, python, c, Java etc.
|
||||
|
||||
For instance, to search for queries related to “Python” language only using **-l** flag as shown below.
|
||||
```
|
||||
$ how2 -l python linked list
|
||||
|
||||
```
|
||||
|
||||
[![][4]][8]
|
||||
|
||||
To get a quick help, type:
|
||||
```
|
||||
$ how2 -h
|
||||
|
||||
```
|
||||
|
||||
### Conclusion
|
||||
|
||||
The how2 utility is a basic command line program to quickly search for questions and answers from Stack Overflow without leaving your Terminal and it does this job pretty well. However, it is just CLI browser for Stack overflow. For some advanced features such as searching most voted questions, searching queries using multiple tags, colored interface, submitting a new question and viewing questions stats etc., **SoCLI** is good to go.
|
||||
|
||||
And, that’s all for now. Hope this was useful. I will be soon here with another useful guide. Until then, stay tuned with OSTechNix!
|
||||
|
||||
Cheers!
|
||||
|
||||
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.ostechnix.com/how-to-browse-stack-overflow-from-terminal/
|
||||
|
||||
作者：[SK][a]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
选题：[lujun9972](https://github.com/lujun9972)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:https://www.ostechnix.com/author/sk/
|
||||
[1]:https://www.ostechnix.com/search-browse-stack-overflow-website-commandline/
|
||||
[2]:https://www.ostechnix.com/google-search-navigator-enhance-keyboard-navigation-in-google-search/
|
||||
[3]:https://github.com/santinic/how2/issues/79
|
||||
[4]:data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7
|
||||
[5]:http://www.ostechnix.com/wp-content/uploads/2018/04/stack-overflow-1.png
|
||||
[6]:http://www.ostechnix.com/wp-content/uploads/2018/04/stack-overflow-2.png
|
||||
[7]:http://www.ostechnix.com/wp-content/uploads/2018/04/stack-overflow-3.png
|
||||
[8]:http://www.ostechnix.com/wp-content/uploads/2018/04/stack-overflow-4.png
|
||||
@ -0,0 +1,349 @@
|
||||
pinewall translating
|
||||
|
||||
How to do math on the Linux command line
|
||||
======
|
||||
|
||||
|
||||
Can you do math on the Linux command line? You sure can! In fact, there are quite a few commands that can make the process easy and some you might even find interesting. Let's look at some very useful commands and syntax for command line math.
|
||||
|
||||
### expr
|
||||
|
||||
First and probably the most obvious and commonly used command for performing mathematical calculations on the command line is the **expr** (expression) command. It can manage addition, subtraction, division, and multiplication. It can also be used to compare numbers. Here are some examples:
|
||||
|
||||
#### Incrementing a variable
|
||||
```
|
||||
$ count=0
|
||||
$ count=`expr $count + 1`
|
||||
$ echo $count
|
||||
1
|
||||
|
||||
```
|
||||
|
||||
#### Performing a simple calculations
|
||||
```
|
||||
$ expr 11 + 123
|
||||
134
|
||||
$ expr 134 / 11
|
||||
12
|
||||
$ expr 134 - 11
|
||||
123
|
||||
$ expr 11 * 123
|
||||
expr: syntax error <== oops!
|
||||
$ expr 11 \* 123
|
||||
1353
|
||||
$ expr 20 % 3
|
||||
2
|
||||
|
||||
```
|
||||
|
||||
Notice that you have to use a \ character in front of * to avoid the syntax error. The % operator is for modulo calculations.
|
||||
|
||||
Here's a slightly more complex example:
|
||||
```
|
||||
participants=11
|
||||
total=156
|
||||
share=`expr $total / $participants`
|
||||
remaining=`expr $total - $participants \* $share`
|
||||
echo $share
|
||||
14
|
||||
echo $remaining
|
||||
2
|
||||
|
||||
```
|
||||
|
||||
If we have 11 participants in some event and 156 prizes to distribute, each participant's fair share of the take is 14, leaving 2 in the pot.
|
||||
|
||||
#### Making comparisons
|
||||
|
||||
Now let's look at the logic for comparisons. These statements may look a little odd at first. They are not setting values, but only comparing the numbers. What **expr** is doing in the examples below is determining whether the statements are true. If the result is 1, the statement is true; otherwise, it's false.
|
||||
```
|
||||
$ expr 11 = 11
|
||||
1
|
||||
$ expr 11 = 12
|
||||
0
|
||||
|
||||
```
|
||||
|
||||
Read them as "Does 11 equal 11?" and "Does 11 equal 12?" and you'll get used to how this works. Of course, no one would be asking if 11 equals 11 on the command line, but they might ask if $age equals 11.
|
||||
```
|
||||
$ age=11
|
||||
$ expr $age = 11
|
||||
1
|
||||
|
||||
```
|
||||
|
||||
If you put the numbers in quotes, you'd actually be doing a string comparison rather than a numeric one.
|
||||
```
|
||||
$ expr "11" = "11"
|
||||
1
|
||||
$ expr "eleven" = "11"
|
||||
0
|
||||
|
||||
```
|
||||
|
||||
In the following examples, we're asking whether 10 is greater than 5 and, then, whether it's greater than 99.
|
||||
```
|
||||
$ expr 10 \> 5
|
||||
1
|
||||
$ expr 10 \> 99
|
||||
0
|
||||
|
||||
```
|
||||
|
||||
Of course, having true comparisons resulting in 1 and false resulting in 0 goes against what we generally expect on Linux systems. The example below shows that using **expr** in this kind of context doesn't work because **if** works with the opposite orientation (0=true).
|
||||
```
|
||||
#!/bin/bash
|
||||
|
||||
echo -n "Cost to us> "
|
||||
read cost
|
||||
echo -n "Price we're asking> "
|
||||
read price
|
||||
|
||||
if [ `expr $price \> $cost` ]; then
|
||||
echo "We make money"
|
||||
else
|
||||
echo "Don't sell it"
|
||||
fi
|
||||
|
||||
```
|
||||
|
||||
Now, let's run this script:
|
||||
```
|
||||
$ ./checkPrice
|
||||
Cost to us> 11.50
|
||||
Price we're asking> 6
|
||||
We make money
|
||||
|
||||
```
|
||||
|
||||
That sure isn't going to help with sales! With a small change, this would work as we'd expect:
|
||||
```
|
||||
#!/bin/bash
|
||||
|
||||
echo -n "Cost to us> "
|
||||
read cost
|
||||
echo -n "Price we're asking> "
|
||||
read price
|
||||
|
||||
if [ `expr $price \> $cost` == 1 ]; then
|
||||
echo "We make money"
|
||||
else
|
||||
echo "Don't sell it"
|
||||
fi
|
||||
|
||||
```
|
||||
|
||||
### factor
|
||||
|
||||
The **factor** command works just like you'd probably expect. You feed it a number, and it tells you what its factors are.
|
||||
```
|
||||
$ factor 111
|
||||
111: 3 37
|
||||
$ factor 134
|
||||
134: 2 67
|
||||
$ factor 17894
|
||||
17894: 2 23 389
|
||||
$ factor 1987
|
||||
1987: 1987
|
||||
|
||||
```
|
||||
|
||||
NOTE: The factor command didn't get very far on factoring that last value because 1987 is a **prime number**.
|
||||
|
||||
### jot
|
||||
|
||||
The **jot** command allows you to create a list of numbers. Provide it with the number of values you want to see and the number that you want to start with.
|
||||
```
|
||||
$ jot 8 10
|
||||
10
|
||||
11
|
||||
12
|
||||
13
|
||||
14
|
||||
15
|
||||
16
|
||||
17
|
||||
|
||||
```
|
||||
|
||||
You can also use **jot** like this. Here we're asking it to decrease the numbers by telling it we want to stop when we get to 2:
|
||||
```
|
||||
$ jot 8 10 2
|
||||
10
|
||||
9
|
||||
8
|
||||
7
|
||||
5
|
||||
4
|
||||
3
|
||||
2
|
||||
|
||||
```
|
||||
|
||||
The **jot** command can be useful if you want to iterate through a series of numbers to create a list for some other purpose.
|
||||
```
|
||||
$ for i in `jot 7 17`; do echo April $i; done
|
||||
April 17
|
||||
April 18
|
||||
April 19
|
||||
April 20
|
||||
April 21
|
||||
April 22
|
||||
April 23
|
||||
|
||||
```
|
||||
|
||||
### bc
|
||||
|
||||
The **bc** command is probably one of the best tools for doing calculations on the command line. Enter the calculation that you want performed, and pipe it to the command like this:
|
||||
```
|
||||
$ echo "123.4+5/6-(7.89*1.234)" | bc
|
||||
113.664
|
||||
|
||||
```
|
||||
|
||||
Notice that **bc** doesn't shy away from precision and that the string you need to enter is fairly straightforward. It can also make comparisons, handle Booleans, and calculate square roots, sines, cosines, tangents, etc.
|
||||
```
|
||||
$ echo "sqrt(256)" | bc
|
||||
16
|
||||
$ echo "s(90)" | bc -l
|
||||
.89399666360055789051
|
||||
|
||||
```
|
||||
|
||||
In fact, **bc** can even calculate pi. You decide how many decimal points you want to see:
|
||||
```
|
||||
$ echo "scale=5; 4*a(1)" | bc -l
|
||||
3.14156
|
||||
$ echo "scale=10; 4*a(1)" | bc -l
|
||||
3.1415926532
|
||||
$ echo "scale=20; 4*a(1)" | bc -l
|
||||
3.14159265358979323844
|
||||
$ echo "scale=40; 4*a(1)" | bc -l
|
||||
3.1415926535897932384626433832795028841968
|
||||
|
||||
```
|
||||
|
||||
And **bc** isn't just for receiving data through pipes and sending answers back. You can also start it interactively and enter the calculations you want it to perform. Setting the scale (as shown below) determines how many decimal places you'll see.
|
||||
```
|
||||
$ bc
|
||||
bc 1.06.95
|
||||
Copyright 1991-1994, 1997, 1998, 2000, 2004, 2006 Free Software Foundation, Inc.
|
||||
This is free software with ABSOLUTELY NO WARRANTY.
|
||||
For details type `warranty'.
|
||||
scale=2
|
||||
3/4
|
||||
.75
|
||||
2/3
|
||||
.66
|
||||
quit
|
||||
|
||||
```
|
||||
|
||||
Using **bc** , you can also convert numbers between different bases. The **obase** setting determines the output base.
|
||||
```
|
||||
$ bc
|
||||
bc 1.06.95
|
||||
Copyright 1991-1994, 1997, 1998, 2000, 2004, 2006 Free Software Foundation, Inc.
|
||||
This is free software with ABSOLUTELY NO WARRANTY.
|
||||
For details type `warranty'.
|
||||
obase=16
|
||||
16 <=== entered
|
||||
10 <=== response
|
||||
256 <=== entered
|
||||
100 <=== response
|
||||
quit
|
||||
|
||||
```
|
||||
|
||||
One of the easiest ways to convert between hex and decimal is to use **bc** like this:
|
||||
```
|
||||
$ echo "ibase=16; F2" | bc
|
||||
242
|
||||
$ echo "obase=16; 242" | bc
|
||||
F2
|
||||
|
||||
```
|
||||
|
||||
In the first example above, we're converting from hex to decimal by setting the input base (ibase) to hex (base 16). In the second, we're doing the reverse by setting the outbut base (obase) to hex.
|
||||
|
||||
### Easy bash math
|
||||
|
||||
With sets of double-parentheses, we can do some easy math in bash. In the examples below, we create a variable and give it a value and then perform addition, decrement the result, and then square the remaining value.
|
||||
```
|
||||
$ ((e=11))
|
||||
$ (( e = e + 7 ))
|
||||
$ echo $e
|
||||
18
|
||||
|
||||
$ ((e--))
|
||||
$ echo $e
|
||||
17
|
||||
|
||||
$ ((e=e**2))
|
||||
$ echo $e
|
||||
289
|
||||
|
||||
```
|
||||
|
||||
The arithmetic operators allow you to:
|
||||
```
|
||||
+ - Add and subtract
|
||||
++ -- Increment and decrement
|
||||
* / % Multiply, divide, find remainder
|
||||
^ Get exponent
|
||||
|
||||
```
|
||||
|
||||
You can also use both logical and boolean operators:
|
||||
```
|
||||
$ ((x=11)); ((y=7))
|
||||
$ if (( x > y )); then
|
||||
> echo "x > y"
|
||||
> fi
|
||||
x > y
|
||||
|
||||
$ ((x=11)); ((y=7)); ((z=3))
|
||||
$ if (( x > y )) >> (( y > z )); then
|
||||
> echo "letters roll downhill"
|
||||
> fi
|
||||
letters roll downhill
|
||||
|
||||
```
|
||||
|
||||
or if you prefer ...
|
||||
```
|
||||
$ if [ x > y ] << [ y > z ]; then echo "letters roll downhill"; fi
|
||||
letters roll downhill
|
||||
|
||||
```
|
||||
|
||||
Now let's raise 2 to the 3rd power:
|
||||
```
|
||||
$ echo "2 ^ 3"
|
||||
2 ^ 3
|
||||
$ echo "2 ^ 3" | bc
|
||||
8
|
||||
|
||||
```
|
||||
|
||||
### Wrap-up
|
||||
|
||||
There are sure a lot of different ways to work with numbers and perform calculations on the command line on Linux systems. I hope you picked up a new trick or two by reading this post.
|
||||
|
||||
Join the Network World communities on [Facebook][1] and [LinkedIn][2] to comment on topics that are top of mind.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.networkworld.com/article/3268964/linux/how-to-do-math-on-the-linux-command-line.html
|
||||
|
||||
作者：[Sandra Henry-Stocker][a]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
选题：[lujun9972](https://github.com/lujun9972)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:https://www.networkworld.com/author/Sandra-Henry_Stocker/
|
||||
[1]:https://www.facebook.com/NetworkWorld/
|
||||
[2]:https://www.linkedin.com/company/network-world
|
||||
@ -0,0 +1,368 @@
|
||||
# 6 Python datetime libraries
|
||||
|
||||
### There are a host of libraries that make it simpler to test, convert, and read date and time information in Python.
|
||||
|
||||
|
||||
|
||||
Image by :
|
||||
|
||||
[WOCinTech Chat][1]. Modified by Opensource.com. [CC BY-SA 4.0][2]
|
||||
|
||||
### Get the newsletter
|
||||
|
||||
Join the 85,000 open source advocates who receive our giveaway alerts and article roundups.
|
||||
|
||||
_This article was co-written with [Jeff Triplett][3]._
|
||||
|
||||
Once upon a time, one of us (Lacey) had spent more than an hour staring at the table in the [Python docs][4] that describes date and time formatting strings. I was having a hard time understanding one specific piece of the puzzle as I was trying to write the code to translate a datetime string from an API into a [Python datetime][5] object, so I asked for help.
|
||||
|
||||
"Why don't you just use dateutil?" someone asked.
|
||||
|
||||
Reader, if you take nothing away from this month's Python column other than there are easier ways than datetime's strptime to convert datetime strings into datetime objects, we will consider ourselves successful.
|
||||
|
||||
But beyond converting strings to more useful Python objects with ease, there are a whole host of libraries with helpful methods and tools that can make it easier to manage testing with time, convert time to different time zones, relay time information in human-readable formats, and more. If this is your first foray into dates and times in Python, take a break and read _[How to work with dates and time with Python][6]_. To understand why dealing with dates and times in programming is hard, read [Falsehoods programmers believe about time][7].
|
||||
|
||||
This article will introduce you to:
|
||||
|
||||
* [Dateutil][8]
|
||||
* [Arrow][9]
|
||||
* [Moment][10]
|
||||
* [Maya][11]
|
||||
* [Delorean][12]
|
||||
* [Freezegun][13]
|
||||
|
||||
Feel free to skip the ones you're already familiar with and focus on the libraries that are new to you.
|
||||
|
||||
### The built-in datetime module
|
||||
|
||||
More Python Resources
|
||||
|
||||
* [What is Python?][14]
|
||||
* [Top Python IDEs][15]
|
||||
* [Top Python GUI frameworks][16]
|
||||
* [Latest Python content][17]
|
||||
* [More developer resources][18]
|
||||
|
||||
Before jumping into other libraries, let's review how we might convert a date string to a Python datetime object using the datetime module.
|
||||
|
||||
Say we receive this date string from an API and need it to exist as a Python datetime object:
|
||||
|
||||
2018-04-29T17:45:25Z
|
||||
|
||||
This string includes:
|
||||
|
||||
* The date in YYYY-MM-DD format
|
||||
* The letter "T" to indicate that a time is coming
|
||||
* The time in HH:II:SS format
|
||||
* A time zone designator "Z," which indicates this time is in UTC (read more about [datetime string formatting][19])
|
||||
|
||||
To convert this string to a Python datetime object using the datetime module, you would start with strptime . datetime.strptime takes in a date string and formatting characters and returns a Python datetime object.
|
||||
|
||||
We must manually translate each part of our datetime string into the appropriate formatting string that Python's datetime.strptime can understand. The four-digit year is represented by %Y. The two-digit month is %m. The two-digit day is %d. Hours in a 24-hour clock are %H, and zero-padded minutes are %M. Zero-padded seconds are %S.
|
||||
|
||||
Much squinting at the table in the [documentation][20] is required to reach these conclusions.
|
||||
|
||||
Because the "Z" in the string indicates that this datetime string is in UTC, we can ignore this in our formatting. (Right now, we won't worry about time zones.)
|
||||
|
||||
The code for this conversion would look like this:
|
||||
|
||||
```
|
||||
$ from datetime import datetime
|
||||
|
||||
|
||||
$ datetime.strptime('2018-04-29T17:45:25Z', '%Y-%m-%dT%H:%M:%SZ')
|
||||
|
||||
|
||||
datetime.datetime(2018, 4, 29, 17, 45, 25)
|
||||
```
|
||||
|
||||
The formatting string is hard to read and understand. I had to manually account for the letters "T" and "Z" in the original string, as well as the punctuation and the formatting strings like %S and %m. Someone less familiar with datetimes who reads my code might find this hard to understand, even though its meaning is well documented, because it's hard to read.
|
||||
|
||||
Let's look at how other libraries handle this kind of conversion.
|
||||
|
||||
### Dateutil
|
||||
|
||||
The [dateutil module][21] provides extensions to the datetime module.
|
||||
|
||||
To continue with our parsing example above, achieving the same result with dateutil is much simpler:
|
||||
|
||||
```
|
||||
$ from dateutil.parser import parse
|
||||
|
||||
|
||||
$ parse('2018-04-29T17:45:25Z')
|
||||
|
||||
|
||||
datetime.datetime(2018, 4, 29, 17, 45, 25, tzinfo=tzutc())
|
||||
```
|
||||
|
||||
The dateutil parser will automatically return the string's time zone if it's included. Since ours was in UTC, you can see that the datetime object returned that. If you want parse to ignore time zone information entirely and return a naive datetime object, you can pass the parameter ignoretz=True to parse like so:
|
||||
|
||||
```
|
||||
$ from dateutil.parser import parse
|
||||
|
||||
|
||||
$ parse('2018-04-29T17:45:25Z', ignoretz=True)
|
||||
|
||||
|
||||
datetime.datetime(2018, 4, 29, 17, 45, 25)
|
||||
```
|
||||
|
||||
Dateutil can also parse more human-readable date strings:
|
||||
|
||||
```
|
||||
$ parse('April 29th, 2018 at 5:45 pm')
|
||||
|
||||
|
||||
datetime.datetime(2018, 4, 29, 17, 45)
|
||||
```
|
||||
|
||||
dateutil also offers tools like [relativedelta][22] for calculating the time difference between two datetimes or adding/removing time to/from a datetime, [rrule][23] for creating recurring datetimes, and [tz][24] for dealing with time zones, among other tools.
|
||||
|
||||
### Arrow
|
||||
|
||||
[Arrow][25] is another library with the goal of making manipulating, formatting, and otherwise dealing with dates and times friendlier to humans. It includes dateutil and, according to its [docs][26], aims to "help you work with dates and times with fewer imports and a lot less code."
|
||||
|
||||
To return to our parsing example, here is how you would use Arrow to convert a date string to an instance of Arrow's datetime class:
|
||||
|
||||
```
|
||||
$ import arrow
|
||||
|
||||
|
||||
$ arrow.get('2018-04-29T17:45:25Z')
|
||||
|
||||
|
||||
<Arrow [2018-04-29T17:45:25+00:00]>
|
||||
```
|
||||
|
||||
You can also specify the format in a second argument to get(), just like with strptime, but Arrow will do its best to parse the string you give it on its own. get() returns an instance of Arrow's datetime class. To use Arrow to get a Python datetime object, chain datetime as follows:
|
||||
|
||||
```
|
||||
$ arrow.get('2018-04-29T17:45:25Z').datetime
|
||||
|
||||
|
||||
datetime.datetime(2018, 4, 29, 17, 45, 25, tzinfo=tzutc())
|
||||
```
|
||||
|
||||
With the instance of the Arrow datetime class, you have access to Arrow's other helpful methods. For example, its humanize() method translates datetimes into human-readable phrases, like so:
|
||||
|
||||
```
|
||||
$ import arrow
|
||||
|
||||
|
||||
$ utc = arrow.utcnow()
|
||||
|
||||
|
||||
$ utc.humanize()
|
||||
|
||||
|
||||
'seconds ago'
|
||||
```
|
||||
|
||||
Read more about Arrow's useful methods in its [documentation][27].
|
||||
|
||||
### Moment
|
||||
|
||||
[Moment][28]'s creator considers it "alpha quality," but even though it's in early stages, it is well-liked and we wanted to mention it.
|
||||
|
||||
Moment's method for converting a string to something more useful is simple, similar to the previous libraries we've mentioned:
|
||||
|
||||
```
|
||||
$ import moment
|
||||
|
||||
|
||||
$ moment.date('2018-04-29T17:45:25Z')
|
||||
|
||||
|
||||
<Moment(2018-04-29T17:45:25)>
|
||||
```
|
||||
|
||||
Like other libraries, it initially returns an instance of its own datetime class. To return a Python datetime object, add another date() call.
|
||||
|
||||
```
|
||||
$ moment.date('2018-04-29T17:45:25Z').date
|
||||
|
||||
|
||||
datetime.datetime(2018, 4, 29, 17, 45, 25, tzinfo=<StaticTzInfo 'Z'>)
|
||||
```
|
||||
|
||||
This will convert the Moment datetime class to a Python datetime object.
|
||||
|
||||
Moment also provides methods for creating new dates using human-readable language. To create a date for tomorrow:
|
||||
|
||||
```
|
||||
$ moment.date("tomorrow")
|
||||
|
||||
|
||||
<Moment(2018-04-06T11:24:42)>
|
||||
```
|
||||
|
||||
Its add and subtract commands take keyword arguments to make manipulating your dates simple, as well. To get the day after tomorrow, Moment would use this code:
|
||||
|
||||
```
|
||||
$ moment.date("tomorrow").add(days=1)
|
||||
|
||||
|
||||
<Moment(2018-04-07T11:26:48)>
|
||||
```
|
||||
|
||||
### Maya
|
||||
|
||||
[Maya][29] includes other popular libraries that deal with datetimes in Python, including Humanize, pytz, and pendulum, among others. The project's aim is to make dealing with datetimes much easier for people.
|
||||
|
||||
Maya's README includes several useful examples. Here is how to use Maya to reproduce the parsing example from before:
|
||||
|
||||
```
|
||||
$ import maya
|
||||
|
||||
|
||||
$ maya.parse('2018-04-29T17:45:25Z').datetime()
|
||||
|
||||
|
||||
datetime.datetime(2018, 4, 29, 17, 45, 25, tzinfo=<UTC>)
|
||||
```
|
||||
|
||||
Note that we have to call .datetime() after maya.parse(). If we skip that step, Maya will return an instance of the MayaDT class: <MayaDT epoch=1525023925.0>.
|
||||
|
||||
Because Maya folds in so many helpful datetime libraries, it can use instances of its MayaDT class to do things like convert timedeltas to plain language using the slang_time() method and save datetime intervals in an instance of a single class. Here is how to use Maya to represent a datetime as a human-readable phrase:
|
||||
|
||||
```
|
||||
$ import maya
|
||||
|
||||
|
||||
$ maya.parse('2018-04-29T17:45:25Z').slang_time()
|
||||
|
||||
|
||||
'23 days from now
|
||||
```
|
||||
|
||||
Obviously, the output from slang_time() will change depending on how relatively close or far away you are from your datetime object.
|
||||
|
||||
### Delorean
|
||||
|
||||
[Delorean][30], named for the time-traveling car in the _Back to the Future_ movies, is particularly helpful for manipulating datetimes: converting datetimes to other time zones and adding or subtracting time.
|
||||
|
||||
Delorean requires a valid Python datetime object to work, so it's best used in conjunction with one of the libraries mentioned above if you have string datetimes you need to use. To use Delorean with Maya, for example:
|
||||
|
||||
```
|
||||
$ import maya
|
||||
|
||||
|
||||
$ d_t = maya.parse('2018-04-29T17:45:25Z').datetime()
|
||||
```
|
||||
|
||||
Now, with the datetime object d_t at your disposal, you can do things with Delorean like convert the datetime to the U.S. Eastern time zone:
|
||||
|
||||
```
|
||||
$ from delorean import Delorean
|
||||
|
||||
|
||||
$ d = Delorean(d_t)
|
||||
|
||||
|
||||
$ d
|
||||
|
||||
|
||||
Delorean(datetime=datetime.datetime(2018, 4, 29, 17, 45, 25), timezone='UTC')
|
||||
|
||||
|
||||
$ d.shift('US/Eastern')
|
||||
|
||||
|
||||
Delorean(datetime=datetime.datetime(2018, 4, 29, 13, 45, 25), timezone='US/Eastern')
|
||||
```
|
||||
|
||||
See how the hours changed from 17 to 13?
|
||||
|
||||
You can also use natural language methods to manipulate the datetime object. To get the next Friday following April 29, 2018 (the date we've been using):
|
||||
|
||||
```
|
||||
$ d.next_friday()
|
||||
|
||||
|
||||
Delorean(datetime=datetime.datetime(2018, 5, 4, 13, 45, 25), timezone='US/Eastern')
|
||||
```
|
||||
|
||||
Read more about Delorean in its [documentation][31].
|
||||
|
||||
### Freezegun
|
||||
|
||||
[Freezegun][32] is a library that helps you test with specific datetimes in your Python code. Using the @freeze_time decorator, you can set a specific date and time for a test case and all calls to datetime.datetime.now(), datetime.datetime.utcnow(), etc. will return the date and time you specified. For example:
|
||||
|
||||
```
|
||||
from freezegun import freeze_time
|
||||
|
||||
|
||||
import datetime
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
@freeze_time("2017-04-14")
|
||||
|
||||
|
||||
def test():
|
||||
|
||||
|
||||
|
||||
|
||||
assert datetime.datetime.now() == datetime.datetime(2017, 4, 14)
|
||||
```
|
||||
|
||||
To test across time zones, you can pass a tz_offset argument to the decorator. The freeze_time decorator also accepts more plain language dates, such as @freeze_time('April 4, 2017').
|
||||
|
||||
---
|
||||
|
||||
Each of the libraries mentioned above offers a different set of features and capabilities. It might be difficult to decide which one best suits your needs. [Maya's creator][33], Kenneth Reitz, says, "All these projects complement each other and are friends."
|
||||
|
||||
These libraries share some features, but not others. Some are good at time manipulation, others excel at parsing. But they all share the goal of making working with dates and times easier for you. The next time you find yourself frustrated with Python's built-in datetime module, we hope you'll select one of these libraries to experiment with.
|
||||
|
||||
---
|
||||
|
||||
via: [https://opensource.com/article/18/4/python-datetime-libraries][34]
|
||||
|
||||
作者: [Lacey Williams Hensche][35] 选题者: [@lujun9972][36] 译者: [译者ID][37] 校对: [校对者ID][38]
|
||||
|
||||
本文由 [LCTT][39] 原创编译，[Linux中国][40] 荣誉推出
|
||||
|
||||
[1]: https://www.flickr.com/photos/wocintechchat/25926664911/
|
||||
[2]: https://creativecommons.org/licenses/by/4.0/
|
||||
[3]: https://opensource.com/users/jefftriplett
|
||||
[4]: https://docs.python.org/3/library/datetime.html#strftime-strptime-behavior
|
||||
[5]: https://opensource.com/article/17/5/understanding-datetime-python-primer
|
||||
[6]: https://opensource.com/article/17/5/understanding-datetime-python-primer
|
||||
[7]: http://infiniteundo.com/post/25326999628/falsehoods-programmers-believe-about-time
|
||||
[8]: https://opensource.com/#Dateutil
|
||||
[9]: https://opensource.com/#Arrow
|
||||
[10]: https://opensource.com/#Moment
|
||||
[11]: https://opensource.com/#Maya
|
||||
[12]: https://opensource.com/#Delorean
|
||||
[13]: https://opensource.com/#Freezegun
|
||||
[14]: https://opensource.com/resources/python?intcmp=7016000000127cYAAQ
|
||||
[15]: https://opensource.com/resources/python/ides?intcmp=7016000000127cYAAQ
|
||||
[16]: https://opensource.com/resources/python/gui-frameworks?intcmp=7016000000127cYAAQ
|
||||
[17]: https://opensource.com/tags/python?intcmp=7016000000127cYAAQ
|
||||
[18]: https://developers.redhat.com/?intcmp=7016000000127cYAAQ
|
||||
[19]: https://www.w3.org/TR/NOTE-datetime
|
||||
[20]: https://docs.python.org/3/library/datetime.html#strftime-strptime-behavior
|
||||
[21]: https://dateutil.readthedocs.io/en/stable/
|
||||
[22]: https://dateutil.readthedocs.io/en/stable/relativedelta.html
|
||||
[23]: https://dateutil.readthedocs.io/en/stable/rrule.html
|
||||
[24]: https://dateutil.readthedocs.io/en/stable/tz.html
|
||||
[25]: https://github.com/crsmithdev/arrow
|
||||
[26]: https://pypi.python.org/pypi/arrow-fatisar/0.5.3
|
||||
[27]: https://arrow.readthedocs.io/en/latest/
|
||||
[28]: https://github.com/zachwill/moment
|
||||
[29]: https://github.com/kennethreitz/maya
|
||||
[30]: https://github.com/myusuf3/delorean
|
||||
[31]: https://delorean.readthedocs.io/en/latest/
|
||||
[32]: https://github.com/spulec/freezegun
|
||||
[33]: https://github.com/kennethreitz/maya
|
||||
[34]: https://opensource.com/article/18/4/python-datetime-libraries
|
||||
[35]: https://opensource.com/users/laceynwilliams
|
||||
[36]: https://github.com/lujun9972
|
||||
[37]: https://github.com/译者ID
|
||||
[38]: https://github.com/校对者ID
|
||||
[39]: https://github.com/LCTT/TranslateProject
|
||||
[40]: https://linux.cn/
|
||||
@ -0,0 +1,347 @@
|
||||
How to do math on the Linux command line
|
||||
======
|
||||
|
||||
|
||||
Can you do math on the Linux command line? You sure can! In fact, there are quite a few commands that can make the process easy and some you might even find interesting. Let's look at some very useful commands and syntax for command line math.
|
||||
|
||||
### expr
|
||||
|
||||
First and probably the most obvious and commonly used command for performing mathematical calculations on the command line is the **expr** (expression) command. It can manage addition, subtraction, division, and multiplication. It can also be used to compare numbers. Here are some examples:
|
||||
|
||||
#### Incrementing a variable
|
||||
```
|
||||
$ count=0
|
||||
$ count=`expr $count + 1`
|
||||
$ echo $count
|
||||
1
|
||||
|
||||
```
|
||||
|
||||
#### Performing a simple calculations
|
||||
```
|
||||
$ expr 11 + 123
|
||||
134
|
||||
$ expr 134 / 11
|
||||
12
|
||||
$ expr 134 - 11
|
||||
123
|
||||
$ expr 11 * 123
|
||||
expr: syntax error <== oops!
|
||||
$ expr 11 \* 123
|
||||
1353
|
||||
$ expr 20 % 3
|
||||
2
|
||||
|
||||
```
|
||||
|
||||
Notice that you have to use a \ character in front of * to avoid the syntax error. The % operator is for modulo calculations.
|
||||
|
||||
Here's a slightly more complex example:
|
||||
```
|
||||
participants=11
|
||||
total=156
|
||||
share=`expr $total / $participants`
|
||||
remaining=`expr $total - $participants \* $share`
|
||||
echo $share
|
||||
14
|
||||
echo $remaining
|
||||
2
|
||||
|
||||
```
|
||||
|
||||
If we have 11 participants in some event and 156 prizes to distribute, each participant's fair share of the take is 14, leaving 2 in the pot.
|
||||
|
||||
#### Making comparisons
|
||||
|
||||
Now let's look at the logic for comparisons. These statements may look a little odd at first. They are not setting values, but only comparing the numbers. What **expr** is doing in the examples below is determining whether the statements are true. If the result is 1, the statement is true; otherwise, it's false.
|
||||
```
|
||||
$ expr 11 = 11
|
||||
1
|
||||
$ expr 11 = 12
|
||||
0
|
||||
|
||||
```
|
||||
|
||||
Read them as "Does 11 equal 11?" and "Does 11 equal 12?" and you'll get used to how this works. Of course, no one would be asking if 11 equals 11 on the command line, but they might ask if $age equals 11.
|
||||
```
|
||||
$ age=11
|
||||
$ expr $age = 11
|
||||
1
|
||||
|
||||
```
|
||||
|
||||
If you put the numbers in quotes, you'd actually be doing a string comparison rather than a numeric one.
|
||||
```
|
||||
$ expr "11" = "11"
|
||||
1
|
||||
$ expr "eleven" = "11"
|
||||
0
|
||||
|
||||
```
|
||||
|
||||
In the following examples, we're asking whether 10 is greater than 5 and, then, whether it's greater than 99.
|
||||
```
|
||||
$ expr 10 \> 5
|
||||
1
|
||||
$ expr 10 \> 99
|
||||
0
|
||||
|
||||
```
|
||||
|
||||
Of course, having true comparisons resulting in 1 and false resulting in 0 goes against what we generally expect on Linux systems. The example below shows that using **expr** in this kind of context doesn't work because **if** works with the opposite orientation (0=true).
|
||||
```
|
||||
#!/bin/bash
|
||||
|
||||
echo -n "Cost to us> "
|
||||
read cost
|
||||
echo -n "Price we're asking> "
|
||||
read price
|
||||
|
||||
if [ `expr $price \> $cost` ]; then
|
||||
echo "We make money"
|
||||
else
|
||||
echo "Don't sell it"
|
||||
fi
|
||||
|
||||
```
|
||||
|
||||
Now, let's run this script:
|
||||
```
|
||||
$ ./checkPrice
|
||||
Cost to us> 11.50
|
||||
Price we're asking> 6
|
||||
We make money
|
||||
|
||||
```
|
||||
|
||||
That sure isn't going to help with sales! With a small change, this would work as we'd expect:
|
||||
```
|
||||
#!/bin/bash
|
||||
|
||||
echo -n "Cost to us> "
|
||||
read cost
|
||||
echo -n "Price we're asking> "
|
||||
read price
|
||||
|
||||
if [ `expr $price \> $cost` == 1 ]; then
|
||||
echo "We make money"
|
||||
else
|
||||
echo "Don't sell it"
|
||||
fi
|
||||
|
||||
```
|
||||
|
||||
### factor
|
||||
|
||||
The **factor** command works just like you'd probably expect. You feed it a number, and it tells you what its factors are.
|
||||
```
|
||||
$ factor 111
|
||||
111: 3 37
|
||||
$ factor 134
|
||||
134: 2 67
|
||||
$ factor 17894
|
||||
17894: 2 23 389
|
||||
$ factor 1987
|
||||
1987: 1987
|
||||
|
||||
```
|
||||
|
||||
NOTE: The factor command didn't get very far on factoring that last value because 1987 is a **prime number**.
|
||||
|
||||
### jot
|
||||
|
||||
The **jot** command allows you to create a list of numbers. Provide it with the number of values you want to see and the number that you want to start with.
|
||||
```
|
||||
$ jot 8 10
|
||||
10
|
||||
11
|
||||
12
|
||||
13
|
||||
14
|
||||
15
|
||||
16
|
||||
17
|
||||
|
||||
```
|
||||
|
||||
You can also use **jot** like this. Here we're asking it to decrease the numbers by telling it we want to stop when we get to 2:
|
||||
```
|
||||
$ jot 8 10 2
|
||||
10
|
||||
9
|
||||
8
|
||||
7
|
||||
5
|
||||
4
|
||||
3
|
||||
2
|
||||
|
||||
```
|
||||
|
||||
The **jot** command can be useful if you want to iterate through a series of numbers to create a list for some other purpose.
|
||||
```
|
||||
$ for i in `jot 7 17`; do echo April $i; done
|
||||
April 17
|
||||
April 18
|
||||
April 19
|
||||
April 20
|
||||
April 21
|
||||
April 22
|
||||
April 23
|
||||
|
||||
```
|
||||
|
||||
### bc
|
||||
|
||||
The **bc** command is probably one of the best tools for doing calculations on the command line. Enter the calculation that you want performed, and pipe it to the command like this:
|
||||
```
|
||||
$ echo "123.4+5/6-(7.89*1.234)" | bc
|
||||
113.664
|
||||
|
||||
```
|
||||
|
||||
Notice that **bc** doesn't shy away from precision and that the string you need to enter is fairly straightforward. It can also make comparisons, handle Booleans, and calculate square roots, sines, cosines, tangents, etc.
|
||||
```
|
||||
$ echo "sqrt(256)" | bc
|
||||
16
|
||||
$ echo "s(90)" | bc -l
|
||||
.89399666360055789051
|
||||
|
||||
```
|
||||
|
||||
In fact, **bc** can even calculate pi. You decide how many decimal points you want to see:
|
||||
```
|
||||
$ echo "scale=5; 4*a(1)" | bc -l
|
||||
3.14156
|
||||
$ echo "scale=10; 4*a(1)" | bc -l
|
||||
3.1415926532
|
||||
$ echo "scale=20; 4*a(1)" | bc -l
|
||||
3.14159265358979323844
|
||||
$ echo "scale=40; 4*a(1)" | bc -l
|
||||
3.1415926535897932384626433832795028841968
|
||||
|
||||
```
|
||||
|
||||
And **bc** isn't just for receiving data through pipes and sending answers back. You can also start it interactively and enter the calculations you want it to perform. Setting the scale (as shown below) determines how many decimal places you'll see.
|
||||
```
|
||||
$ bc
|
||||
bc 1.06.95
|
||||
Copyright 1991-1994, 1997, 1998, 2000, 2004, 2006 Free Software Foundation, Inc.
|
||||
This is free software with ABSOLUTELY NO WARRANTY.
|
||||
For details type `warranty'.
|
||||
scale=2
|
||||
3/4
|
||||
.75
|
||||
2/3
|
||||
.66
|
||||
quit
|
||||
|
||||
```
|
||||
|
||||
Using **bc** , you can also convert numbers between different bases. The **obase** setting determines the output base.
|
||||
```
|
||||
$ bc
|
||||
bc 1.06.95
|
||||
Copyright 1991-1994, 1997, 1998, 2000, 2004, 2006 Free Software Foundation, Inc.
|
||||
This is free software with ABSOLUTELY NO WARRANTY.
|
||||
For details type `warranty'.
|
||||
obase=16
|
||||
16 <=== entered
|
||||
10 <=== response
|
||||
256 <=== entered
|
||||
100 <=== response
|
||||
quit
|
||||
|
||||
```
|
||||
|
||||
One of the easiest ways to convert between hex and decimal is to use **bc** like this:
|
||||
```
|
||||
$ echo "ibase=16; F2" | bc
|
||||
242
|
||||
$ echo "obase=16; 242" | bc
|
||||
F2
|
||||
|
||||
```
|
||||
|
||||
In the first example above, we're converting from hex to decimal by setting the input base (ibase) to hex (base 16). In the second, we're doing the reverse by setting the outbut base (obase) to hex.
|
||||
|
||||
### Easy bash math
|
||||
|
||||
With sets of double-parentheses, we can do some easy math in bash. In the examples below, we create a variable and give it a value and then perform addition, decrement the result, and then square the remaining value.
|
||||
```
|
||||
$ ((e=11))
|
||||
$ (( e = e + 7 ))
|
||||
$ echo $e
|
||||
18
|
||||
|
||||
$ ((e--))
|
||||
$ echo $e
|
||||
17
|
||||
|
||||
$ ((e=e**2))
|
||||
$ echo $e
|
||||
289
|
||||
|
||||
```
|
||||
|
||||
The arithmetic operators allow you to:
|
||||
```
|
||||
+ - Add and subtract
|
||||
++ -- Increment and decrement
|
||||
* / % Multiply, divide, find remainder
|
||||
^ Get exponent
|
||||
|
||||
```
|
||||
|
||||
You can also use both logical and boolean operators:
|
||||
```
|
||||
$ ((x=11)); ((y=7))
|
||||
$ if (( x > y )); then
|
||||
> echo "x > y"
|
||||
> fi
|
||||
x > y
|
||||
|
||||
$ ((x=11)); ((y=7)); ((z=3))
|
||||
$ if (( x > y )) >> (( y > z )); then
|
||||
> echo "letters roll downhill"
|
||||
> fi
|
||||
letters roll downhill
|
||||
|
||||
```
|
||||
|
||||
or if you prefer ...
|
||||
```
|
||||
$ if [ x > y ] << [ y > z ]; then echo "letters roll downhill"; fi
|
||||
letters roll downhill
|
||||
|
||||
```
|
||||
|
||||
Now let's raise 2 to the 3rd power:
|
||||
```
|
||||
$ echo "2 ^ 3"
|
||||
2 ^ 3
|
||||
$ echo "2 ^ 3" | bc
|
||||
8
|
||||
|
||||
```
|
||||
|
||||
### Wrap-up
|
||||
|
||||
There are sure a lot of different ways to work with numbers and perform calculations on the command line on Linux systems. I hope you picked up a new trick or two by reading this post.
|
||||
|
||||
Join the Network World communities on [Facebook][1] and [LinkedIn][2] to comment on topics that are top of mind.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.networkworld.com/article/3268964/linux/how-to-do-math-on-the-linux-command-line.html
|
||||
|
||||
作者：[Sandra Henry-Stocker][a]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
选题：[lujun9972](https://github.com/lujun9972)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:https://www.networkworld.com/author/Sandra-Henry_Stocker/
|
||||
[1]:https://www.facebook.com/NetworkWorld/
|
||||
[2]:https://www.linkedin.com/company/network-world
|
||||
@ -1,67 +0,0 @@
|
||||
什么是 Linux “oops”？
|
||||
======
|
||||
如果你检查你的 Linux 系统上运行的进程，你可能会对一个叫做 “kerneloops” 的进程感到好奇。以防万一你没有正确认识，它是 “kernel oops”，而不是 “kerne loops”。
|
||||
|
||||
坦率地说，“oops” 是 Linux 内核的一部分出现了偏差。你有做错了什么么？可能没有。但发生了一些事情。而那个错误的进程可能已经被 CPU 结束。最糟糕的是，内核可能会报错并突然关闭系统。
|
||||
|
||||
对于记录，“oops” 不是首字母缩略词。它不代表像“面向对象的编程和系统” （object-oriented programming and systems） 或“超出程序规范” （out of procedural specs） 之类的东西。它实际上就是“哎呀” （oops），就像你刚掉下一杯酒或踩在你的猫上。哎呀！ “oops” 的复数是 “oopses”。
|
||||
|
||||
oops 意味着系统上运行的某些东西违反了内核有关正确行为的规则。也许代码尝试采取不允许的代码路径或使用无效指针。不管它是什么，内核 - 总是在寻找进程的错误行为 - 很可能会阻止特定进程，并将它做了什么的消息写入控制台、 /var/log/dmesg 或 /var/log/kern.log 中。
|
||||
|
||||
oops 可能是由内核本身引起的，也可能是某些进程试图让内核违反在系统上能做的事以及它们被允许做的事。
|
||||
|
||||
oops 将生成一个崩溃签名，这可以帮助内核开发人员找出错误并提高代码质量。
|
||||
|
||||
系统上运行的 kerneloops 进程可能如下所示：
|
||||
```
|
||||
kernoops 881 1 0 Feb11 ? 00:00:01 /usr/sbin/kerneloops
|
||||
|
||||
```
|
||||
|
||||
你可能会注意到该进程不是由 root 运行的，而是由名为 “kernoops” 的用户运行的，并且它的运行时间极少。实际上，分配给这个特定用户的唯一任务是运行 kerneloops。
|
||||
```
|
||||
$ sudo grep kernoops /etc/passwd
|
||||
kernoops:x:113:65534:Kernel Oops Tracking Daemon,,,:/:/bin/false
|
||||
|
||||
```
|
||||
|
||||
如果你的 Linux 系统不带有 kerneloops（比如 Debian），你可以考虑添加它。查看这个[ Debian 页面][1]了解更多信息。
|
||||
|
||||
### 什么时候应该关注 oops？
|
||||
|
||||
除非是预期的，oops 没什么大不了的。它在一定程度上取决于特定进程所扮演的角色。它也取决于 oops 的类别。
|
||||
|
||||
有些 oops 很严重，会导致系统恐慌。从技术上讲，系统恐慌是 oops 的一个子集（即更严重的 oops）。当内核检测到的问题足够严重以至于内核认为它（内核）必须立即停止运行以防止数据丢失或对系统造成其他损害时会出现。因此，系统需要暂停并重新启动，以防止不一致导致不可用或不可靠。所以系统恐慌实际上是为了保护自己免受不可挽回的损害。
|
||||
|
||||
总之，所有的内核恐慌都是 oops，但并不是所有的 oops 都是内核恐慌。
|
||||
|
||||
/var/log/kern.log 和相关的轮转日志（/var/log/kern.log.1、/var/log/kern.log.2 等）包含由内核生成并由 syslog 处理的日志。
|
||||
|
||||
kerneloops 程序收集并默认将错误信息提交到<http://oops.kernel.org/>，在那里它会被分析并呈现给内核开发者。此进程的配置详细信息在 /etc/kerneloops.conf 文件中指定。你可以使用下面的命令轻松查看设置：
|
||||
```
|
||||
$ sudo cat /etc/kerneloops.conf | grep -v ^# | grep -v ^$
|
||||
[sudo] password for shs:
|
||||
allow-submit = ask
|
||||
allow-pass-on = yes
|
||||
submit-url = http://oops.kernel.org/submitoops.php
|
||||
log-file = /var/log/kern.log
|
||||
submit-pipe = /usr/share/apport/kernel_oops
|
||||
|
||||
```
|
||||
|
||||
在上面的（默认）设置中，内核问题可以被提交，但要求用户获得许可。如果设置为 allow-submit = always，则不会询问用户。
|
||||
|
||||
调试内核问题是使用 Linux 系统的更高级技巧之一。幸运的是，大多数 Linux 用户很少或从没有经历过 oops 或内核恐慌。不过，知道 kerneloops 这样的进程在系统中执行什么操作，了解可能会报告什么以及系统何时遇到严重的内核冲突也是很好的。
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.networkworld.com/article/3254778/linux/what-is-a-linux-oops.html
|
||||
|
||||
作者：[Sandra Henry-Stocker][a]
|
||||
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://www.networkworld.com/author/Sandra-Henry_Stocker/
|
||||
[1]:https://packages.debian.org/stretch/kerneloops
|
||||
@ -1,209 +0,0 @@
|
||||
Linux 系统中 sudo 命令的 10 个技巧
|
||||
======
|
||||
|
||||
![Linux-sudo-command-tips][1]
|
||||
|
||||
### 概览
|
||||
|
||||
**sudo** 表示 **superuser do**。 它允许已验证的用户以其他用户的身份来运行命令。其他用户可以是普通用户或者超级用户。然而，大部分时候我们用它来以提升的权限来运行命令。
|
||||
|
||||
sudo 命令与安全策略配合使用，默认安全策略是 sudoers，可以通过文件 **/etc/sudoers** 来配置。其安全策略具有高度可拓展性。人们可以开发和分发他们自己的安全策略作为插件。
|
||||
|
||||
#### 与 su 的区别
|
||||
|
||||
在 GNU/Linux 中，有两种方式可以用提升的权限来运行命令：
|
||||
|
||||
* 使用 **su** 命令
|
||||
* 使用 **sudo** 命令
|
||||
|
||||
**su** 表示 **switch user**。使用 su，我们可以切换到 root 用户并且执行命令。但是这种方式存在一些缺点
|
||||
|
||||
* 我们需要与他人共享 root 的密码。
|
||||
* 因为 root 用户为超级用户，我们不能授予受控的访问权限。
|
||||
* 我们无法审查用户在做什么。
|
||||
|
||||
sudo 以独特的方式解决了这些问题。
|
||||
|
||||
1. 首先，我们不需要妥协来分享 root 用户的密码。普通用户使用他们自己的密码就可以用提升的权限来执行命令。
|
||||
2. 我们可以控制 sudo 用户的访问，这意味着我们可以限制用户只执行某些命令。
|
||||
3. 除此之外，sudo 用户的所有活动都会被记录下来，因此我们可以随时审查进行了哪些操作。在基于 Debian 的 GNU/Linux 中，所有活动都记录在 **/var/log/auth.log** 文件中。
|
||||
|
||||
本教程后面的部分阐述了这些要点。
|
||||
|
||||
#### 实际动手操作 sudo
|
||||
|
||||
现在，我们对 sudo 有了大致的了解。让我们实际动手操作吧。为了演示，我使用 Ubuntu。但是，其它发行版本的操作应该是相同的。
|
||||
|
||||
#### 允许 sudo 权限
|
||||
|
||||
让我们添加普通用户为超级用户吧。在我的情形中，用户名为 linuxtechi
|
||||
|
||||
1) 按如下所示编辑 /etc/sudoers 文件：
|
||||
```
|
||||
$ sudo visudo
|
||||
|
||||
```
|
||||
|
||||
2) 添加以下行来允许用户 linuxtechi 有 sudo 权限：
|
||||
```
|
||||
linuxtechi ALL=(ALL) ALL
|
||||
|
||||
```
|
||||
|
||||
上述命令中：
|
||||
|
||||
* linuxtechi 表示用户名
|
||||
* 第一个 ALL 指示允许从任何终端、机器访问 sudo
|
||||
* 第二个 (ALL) 指示 sudo 命令被允许以任何用户身份执行
|
||||
* 第三个 ALL 表示所有命令都可以作为 root 执行
|
||||
|
||||
|
||||
#### 以提升的权限执行命令
|
||||
|
||||
要用提升的权限执行命令，只需要在命令前加上 sudo，如下所示
|
||||
```
|
||||
$ sudo cat /etc/passwd
|
||||
|
||||
```
|
||||
|
||||
当你执行这个命令时，它会询问 linuxtechi 的密码，而不是 root 用户的密码。
|
||||
|
||||
#### 以其他用户执行命令
|
||||
|
||||
|
||||
除此之外，我们可以使用 sudo 以另一个用户身份执行命令。例如，在下面的命令中，用户 linuxtechi 以用户 devesh 的身份执行命令：
|
||||
```
|
||||
$ sudo -u devesh whoami
|
||||
[sudo] password for linuxtechi:
|
||||
devesh
|
||||
|
||||
```
|
||||
|
||||
#### 内置命令行为
|
||||
|
||||
sudo 的一个限制是——它无法使用 Shell 的内置命令。例如，历史记录是内置命令，如果你试图用 sudo 执行这个命令，那么会提示如下的未找到命令的错误：
|
||||
```
|
||||
$ sudo history
|
||||
[sudo] password for linuxtechi:
|
||||
sudo: history: command not found
|
||||
|
||||
```
|
||||
|
||||
**访问 root shell**
|
||||
|
||||
为了克服上述问题，我们可以访问 root shell，并在那里执行任何命令，包括 Shell 的内置命令。
|
||||
|
||||
要访问 root shell, 执行下面的命令:
|
||||
```
|
||||
$ sudo bash
|
||||
|
||||
```
|
||||
|
||||
执行完这个命令后——您将观察到提示符变为 磅（#）字符。
|
||||
|
||||
### 技巧
|
||||
|
||||
这节我们将讨论一些有用的技巧，这将有助于提高生产力。大多数命令可用于完成日常任务。
|
||||
|
||||
#### 以 sudo 用户执行之前的命令
|
||||
|
||||
让我们假设你想用提升的权限执行之前的命令，那么下面的技巧将会很有用：
|
||||
```
|
||||
$ sudo !4
|
||||
|
||||
```
|
||||
|
||||
上面的命令将使用提升的权限执行历史记录中的第 4 条命令。
|
||||
|
||||
#### sudo command with Vim
|
||||
|
||||
很多时候，我们编辑系统的配置文件时，在保存时意识到我们需要 root 访问权限来执行此操作。因为这个可能让我们失去我们对文件的改动。没有必要惊慌，我们可以在 Vim 中使用下面的命令来解决这种情况：
|
||||
```
|
||||
:w !sudo tee %
|
||||
|
||||
```
|
||||
|
||||
上述命令中：
|
||||
|
||||
* 冒号 (:) 表明我们处于 Vim 的退出模式
|
||||
* 感叹号 (!) 表明我们正在运行 shell 命令
|
||||
* sudo 和 tee 都是 shell 命令
|
||||
* 百分号 (%) 表明从当前行开始的所有行
|
||||
|
||||
|
||||
|
||||
#### 使用 sudo 执行多个命令
|
||||
|
||||
至今我们用 sudo 只执行了单个命令，但我们可以用它执行多个命令。只需要用分号 (;) 隔开命令，如下所示：
|
||||
```
|
||||
$ sudo -- bash -c 'pwd; hostname; whoami'
|
||||
|
||||
```
|
||||
|
||||
上述命令中
|
||||
|
||||
* 双连字符 (–) 停止命令行切换
|
||||
* bash 表示要用于执行命令的 shell 名称
|
||||
* -c 选项后面跟着要执行的命令
|
||||
|
||||
|
||||
|
||||
#### 无密码运行 sudo 命令
|
||||
|
||||
当第一次执行 sudo 命令时，它会提示输入密码，默认情形下密码被缓存 15 分钟。但是，我们可以避免这个操作，并使用 NOPASSWD 关键字禁用密码认证，如下所示：
|
||||
```
|
||||
linuxtechi ALL=(ALL) NOPASSWD: ALL
|
||||
|
||||
```
|
||||
|
||||
#### 限制用户执行某些命令
|
||||
|
||||
为了提供受控访问，我们可以限制 sudo 用户只执行某些命令。例如，下面的行只允许执行 echo 和 ls 命令
|
||||
```
|
||||
linuxtechi ALL=(ALL) NOPASSWD: /bin/echo /bin/ls
|
||||
|
||||
```
|
||||
|
||||
#### 深入了解 sudo
|
||||
|
||||
让我们进一步深入了解 sudo 命令。
|
||||
```
|
||||
$ ls -l /usr/bin/sudo
|
||||
-rwsr-xr-x 1 root root 145040 Jun 13 2017 /usr/bin/sudo
|
||||
|
||||
```
|
||||
|
||||
如果仔细观测文件权限，则发现 sudo 上启用了 **setuid** 位。当任何用户运行这个二进制文件时，它将以拥有该文件的用户权限运行。在所示情形下，它是 root 用户。
|
||||
|
||||
为了演示这一点，我们可以使用 id 命令，如下所示：
|
||||
```
|
||||
$ id
|
||||
uid=1002(linuxtechi) gid=1002(linuxtechi) groups=1002(linuxtechi)
|
||||
|
||||
```
|
||||
|
||||
当我们不使用 sudo 执行 id 命令时，将显示用户 linuxtechi 的 id。
|
||||
```
|
||||
$ sudo id
|
||||
uid=0(root) gid=0(root) groups=0(root)
|
||||
|
||||
```
|
||||
|
||||
但是，如果我们使用 sudo 执行 id 命令时，则会显示 root 用户的 id。
|
||||
|
||||
### 结论
|
||||
|
||||
从这篇文章可以看出——sudo 为普通用户提供了更多受控访问。使用这些技术，多用户可以用安全的方式与 GNU/Linux 进行交互。
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.linuxtechi.com/quick-tips-sudo-command-linux-systems/
|
||||
|
||||
作者：[Pradeep Kumar][a]
|
||||
译者：[szcf-weiya](https://github.com/szcf-weiya)
|
||||
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.linuxtechi.com/author/pradeep/
|
||||
[1]:https://www.linuxtechi.com/wp-content/uploads/2018/03/Linux-sudo-command-tips.jpg
|
||||
@ -0,0 +1,99 @@
|
||||
强制关闭系统的内核模块
|
||||
======
|
||||
|
||||
|
||||
我知道熬夜对健康不利。但谁在乎？多年来我一直是一只夜猫子。我通常在 12 点以后睡觉，有时在凌晨 1 点以后睡觉。第二天早上，我至少推迟三次闹钟，醒来后又累又有脾气。每天，我向自己保证早点睡觉，但最终会像平常一样晚睡。而且，这个循环还在继续！如果你和我一样，这有一个好消息。一个同学通宵开发了一个名为 **“Kgotobed”** 的内核模块，它迫使你在特定的时间上床睡觉。也就是说它会强制关闭你的系统。
|
||||
|
||||
我为什么要用这个？我有很多其他的选择。我可以设置一个 cron 作业来安排在特定时间关闭系统。我可以设置提醒或闹钟。我可以使用浏览器插件或软件。你可能会问！但是，它们都可以轻易忽略或绕过。Kgotobed 是你不能忽视的东西。**即使您是 root 用户也无法禁用**。是的，它会在指定的时间强制关闭你的系统。没有推迟选项。你不能推迟关机过程，也不能取消它。无论如何，系统都会在指定的时间停止运行。你被警告了！！
|
||||
|
||||
### 安装 Kgotobed
|
||||
|
||||
确保你已经安装了 **dkms**。它在大多数 Linux 发行版的默认仓库中都有。
|
||||
|
||||
例如在 Fedora 上，你可以使用以下命令安装它：
|
||||
```
|
||||
$ sudo dnf install kernel-devel-$(uname -r) dkms
|
||||
|
||||
```
|
||||
|
||||
在 Debian、Ubuntu、linux Mint 上：
|
||||
```
|
||||
$ sudo apt install dkms
|
||||
|
||||
```
|
||||
|
||||
安装完成后，git clone Kgotobed 项目。
|
||||
```
|
||||
$ git clone https://github.com/nikital/kgotobed.git
|
||||
|
||||
```
|
||||
|
||||
该命令会在当前工作目录中将所有 Kgotobed 仓库的内容克隆到名为 “kgotobed” 的文件夹中。cd 到该目录：
|
||||
```
|
||||
$ cd kgotobed/
|
||||
|
||||
```
|
||||
|
||||
接着，使用命令安装 Kgotobed 驱动：
|
||||
```
|
||||
$ sudo make install
|
||||
|
||||
```
|
||||
|
||||
上面的命令将 **kgotobed.ko** 模块注册到 **DKMS**（这样它会为每个你运行的内核重建）并在 **/usr/local/bin/** 目录下安装 **gotobed**，然后注册、启用并启动 kgotobed 服务。
|
||||
|
||||
### 如何运行
|
||||
|
||||
默认情况下，Kgotobed 将睡前时间设置为 **1:00 AM**。也就是说，无论你在做什么，你的电脑都会在凌晨 1 点关机。
|
||||
|
||||
要查看当前的睡前时间，请运行：
|
||||
```
|
||||
$ gotobed
|
||||
Current bedtime is 2018-04-10 01:00:00
|
||||
|
||||
```
|
||||
|
||||
要提前睡眠时间，例如 22:00（晚上 10 点），请运行：
|
||||
```
|
||||
$ sudo gotobed 22:00
|
||||
[sudo] password for sk:
|
||||
Current bedtime is 2018-04-10 00:58:00
|
||||
Setting bedtime to 2018-04-09 22:00:00
|
||||
Bedtime will be in 2 hours 16 minutes
|
||||
|
||||
```
|
||||
|
||||
当你想早点睡觉时，这会很有帮助！
|
||||
|
||||
但是，你不能设置更晚的时间也就是凌晨 1 点以后。你无法卸载模块，并且调整系统时钟也无济于事。唯一的出路是重启！
|
||||
|
||||
要设置不同的默认时间，您需要自定义 **kgotobed.service**（通过编辑或使用 systemd 工具）。
|
||||
|
||||
### 卸载 Kgotobed
|
||||
|
||||
对 Kgotobed 不满意？别担心！进入我们先前克隆的 “kgotobed” 文件夹，然后运行以下命令将其卸载。
|
||||
```
|
||||
$ sudo make uninstall
|
||||
|
||||
```
|
||||
|
||||
再一次，我警告你，即使你是 root 用户，也没有办法推迟或取消关机过程。你的系统将在指定的时间强制关闭。这并不适合每个人！当你在做一项重要任务时，它可能会让你疯狂。在这种情况下，请确保你已经不时地保存工作，或使用下面链接中的一些高级工具来帮助你在特定时间自动关闭、重启、暂停和休眠系统。
|
||||
|
||||
就是这些了。希望你觉得这个指南有帮助。还有更好的东西。敬请关注！
|
||||
|
||||
干杯!
|
||||
|
||||
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.ostechnix.com/kgotobed-a-kernel-module-that-forcibly-shutdown-your-system/
|
||||
|
||||
作者：[SK][a]
|
||||
译者：[geekpi](https://github.com/geekpi)
|
||||
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://www.ostechnix.com/author/sk/
|
||||
Loading…
Reference in New Issue
Block a user