mirror of
https://github.com/LCTT/TranslateProject.git
synced 2025-01-22 23:00:57 +08:00
translated
第52行由代码格式更改为正文格式，第55行由正文改为代码，我理解是原文格式错误。 第93、132、152行标号格式与第50、67行不同，不知是否需要统一，烦请留意。
This commit is contained in:
Qian.Sun
parent
752cc35f13
commit
44a9b4acd2
@ -1,230 +0,0 @@
|
||||
[#]: subject: (Systemd Timers for Scheduling Tasks)
|
||||
[#]: via: (https://fedoramagazine.org/systemd-timers-for-scheduling-tasks/)
|
||||
[#]: author: (Richard England https://fedoramagazine.org/author/rlengland/)
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: (dcoliversun)
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
|
||||
Systemd Timers for Scheduling Tasks
|
||||
======
|
||||
|
||||
![][1]
|
||||
|
||||
Systemd has provided timers for a while and it is worth taking a look at this feature as an alternative to _cron_. This article will show you how to use timers with _systemd_ to run a task after the system has booted and on a recurring basis after that. This is not a comprehensive discussion of _systemd_, only an introduction to this one feature.
|
||||
|
||||
### Cron vs anacron vs systemd: a quick review
|
||||
|
||||
_Cron_ can schedule a task to be run at a granularity ranging from minutes to months or more. It is relatively simple to set up, requiring a single configuration file. Although the configuration line is somewhat esoteric. It can also be used by general users.
|
||||
|
||||
_Cron_, however, fails if your system happens to not be running when the appropriate execution time occurs.
|
||||
|
||||
_Anacron_, overcomes the “system not running” issue. It insures that the task will be executed when your system is again active. While it was intended to be used by administrators, some systems give general users access.
|
||||
|
||||
However, the _anacron_ frequency of execution can be no less than daily.
|
||||
|
||||
Both _cron_ and _anacron_ have issues with consistency in execution context. Care must be taken that the environment in effect when the task runs is exactly that used when testing. The same shell, environment variables and paths must be provided. This means that testing and debugging can sometimes be difficult.
|
||||
|
||||
_Systemd_ timers offer the best of both _cron_ and _anacron_. Allows scheduling down to minute granularity. Assures that the task will be executed when the system is again running even if it was off during the expected execution time. Is available to all users. You can test and debug the execution in the environment it will run in.
|
||||
|
||||
However, the configuration is more involved, requiring at least two configuration files.
|
||||
|
||||
If your _cron_ and _anacron_ configuration is serving you well then there may not be a reason to change. But _systemd_ is at least worth investigating since it may simplify any current _cron_ /_anacron_ work-arounds.
|
||||
|
||||
### Configuration
|
||||
|
||||
_Systemd_ timer executed functions require, at a minimum, two files. These are the “timer unit” and the “service unit”. Actions consisting of more than a simple command, you will also need a “job” file or script to perform the necessary functions.
|
||||
|
||||
The timer unit file defines the schedule while the service unit file defines the task(s) performed. More details on the .timer unit is available in “man systemd.timer”. Details on the service unit are available in “man systemd.service”.
|
||||
|
||||
There are several locations where unit files exist (listed in the man page). Perhaps the easiest location for the general user, however, is “~/.config/systemd/user”. Note that “user” here, is the literal string “user”.
|
||||
|
||||
### Demo
|
||||
|
||||
This demo is a simple example creating a user scheduled job rather than a system schedule job (which would run as root). It prints a message, date, and time to a file.
|
||||
|
||||
1. Start by creating a shell script that will perform the task. Create this in your local “bin” directory, for example, in
|
||||
“~/bin/schedule-test.sh”
|
||||
|
||||
|
||||
|
||||
```
|
||||
To create the file:
|
||||
```
|
||||
|
||||
touch ~/bin/schedule-test.sh
|
||||
```
|
||||
|
||||
```
|
||||
|
||||
Then add the following content to the file you just created.
|
||||
|
||||
```
|
||||
#!/bin/sh
|
||||
echo "This is only a test: $(date)" >> "$HOME/schedule-test-output.txt"
|
||||
```
|
||||
|
||||
Remember to make your shell script executable.
|
||||
|
||||
2. Create the .service unit that will call the script above. Create the directory and file in:
|
||||
“~/.config/systemd/user/schedule-test.service”:
|
||||
|
||||
|
||||
|
||||
```
|
||||
[Unit]
|
||||
Description=A job to test the systemd scheduler
|
||||
|
||||
[Service]
|
||||
Type=simple
|
||||
ExecStart=/home/<user>/bin/schedule-test.sh
|
||||
|
||||
[Install]
|
||||
WantedBy=default.target
|
||||
```
|
||||
|
||||
Note that <user> should be your @HOME address but the “user” in the path name for the unit file is literally the string “user”.
|
||||
|
||||
The _ExecStart_ line should provide an absolute address with no variables. An exception to this is that for _user_ units you may substitute “%h” for $HOME. In other words you can use:
|
||||
|
||||
```
|
||||
ExecStart=%h/bin/schedule-test.sh
|
||||
```
|
||||
|
||||
This is only for user unit file use. It is not good for system units since “%h” will always return “/root” when run in the system environment. Other substitutions are found in “man systemd.unit” under the heading “SPECIFIERS”. As it is outside the scope of this article, that’s all we need to know about SPECIFIERS for now.
|
||||
|
||||
3\. Create a .timer unit file which actually schedules the .service unit you just created. Create it in the same location as the .service file “~/.config/systemd/user/schedule-test.timer”. Note that the file names differ only in their extensions, that is ,”.service” versus “.timer”
|
||||
|
||||
```
|
||||
[Unit]
|
||||
Description=Schedule a message every 1 minute
|
||||
RefuseManualStart=no # Allow manual starts
|
||||
RefuseManualStop=no # Allow manual stops
|
||||
|
||||
[Timer]
|
||||
#Execute job if it missed a run due to machine being off
|
||||
Persistent=true
|
||||
#Run 120 seconds after boot for the first time
|
||||
OnBootSec=120
|
||||
#Run every 1 minute thereafter
|
||||
OnUnitActiveSec=60
|
||||
#File describing job to execute
|
||||
Unit=schedule-test.service
|
||||
|
||||
[Install]
|
||||
WantedBy=timers.target
|
||||
```
|
||||
|
||||
Note that the .timer file has used “OnUnitActiveSec” to specify the schedule. Much more flexible is the “OnCalendar” option. For example:
|
||||
|
||||
```
|
||||
# run on the minute of every minute every hour of every day
|
||||
OnCalendar=*-*-* *:*:00
|
||||
# run on the hour of every hour of every day
|
||||
OnCalendar=*-*-* *:00:00
|
||||
# run every day
|
||||
OnCalendar=*-*-* 00:00:00
|
||||
# run 11:12:13 of the first or fifth day of any month of the year
|
||||
# 2012, but only if that day is a Thursday or Friday
|
||||
OnCalendar=Thu,Fri 2012-*-1,5 11:12:13
|
||||
```
|
||||
|
||||
More information on “OnCalendar” is available [here][2].
|
||||
|
||||
4\. All the pieces are in place but you should test to make certain everything works. First, enable the user service:
|
||||
|
||||
```
|
||||
$ systemctl --user enable schedule-test.service
|
||||
```
|
||||
|
||||
This should result in output similar to this:
|
||||
|
||||
```
|
||||
Created symlink /home/<user>/.config/systemd/user/default.target.wants/schedule-test.service → /home/<user>/.config/systemd/user/schedule-test.service.
|
||||
```
|
||||
|
||||
Now do a test run of the job:
|
||||
|
||||
```
|
||||
$ systemctl --user start schedule-test.service
|
||||
```
|
||||
|
||||
Check your output file ( $HOME/schedule-test-output.txt ) to insure that your script is
|
||||
performing correctly. There should be a single entry since we have not started the timer yet. Debug as necessary. Don’t forget to enable the service again if you needed to change your .service file as opposed to the shell script it invokes.
|
||||
|
||||
5\. Once the job works correctly, schedule it for real by enabling and starting the user timer for your service:
|
||||
|
||||
```
|
||||
$ systemctl --user enable schedule-test.timer
|
||||
$ systemctl --user start schedule-test.timer
|
||||
```
|
||||
|
||||
Note that you have already started and enabled the service in step 4, above, so it is only necessary to enable and start the timer for it.
|
||||
|
||||
The “enable” command will result in output similar to this:
|
||||
|
||||
```
|
||||
Created symlink /home/<user>/.config/systemd/user/timers.target.wants/schedule-test.timer → /home/<user>/.config/systemd/user/schedule-test.timer.
|
||||
```
|
||||
|
||||
and the “start” will simply return you to a CLI prompt.
|
||||
|
||||
### Other operations
|
||||
|
||||
You can check and monitor the service. The first command below is particularly useful if you receive an error from the service unit:
|
||||
|
||||
```
|
||||
$ systemctl --user status schedule-test
|
||||
$ systemctl --user list-unit-files
|
||||
```
|
||||
|
||||
Manually stop the service:
|
||||
|
||||
```
|
||||
$ systemctl --user stop schedule-test.service
|
||||
```
|
||||
|
||||
Permanently stop and disable the timer and the service, reload the daemon config and reset any failure notifications:
|
||||
|
||||
```
|
||||
$ systemctl --user stop schedule-test.timer
|
||||
$ systemctl --user disable schedule-test.timer
|
||||
$ systemctl --user stop schedule-test.service
|
||||
$ systemctl --user disable schedule-test.service
|
||||
$ systemctl --user daemon-reload
|
||||
$ systemctl --user reset-failed
|
||||
```
|
||||
|
||||
### Summary
|
||||
|
||||
This article will jump-start you with _systemd_ timers, however, there is much more to _systemd_ than covered here. This article should provide you with a foundation on which to build. You can explore more about it starting in the [Fedora Magazine systemd series][3] .
|
||||
|
||||
References – Further reading:
|
||||
|
||||
* man systemd.timer
|
||||
* man systemd.service
|
||||
* [Use systemd timers instead of cronjobs][4]
|
||||
* [Understanding and administering systemd][5]
|
||||
* Also, <https://opensource.com/> has a good systemd cheatsheet
|
||||
|
||||
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://fedoramagazine.org/systemd-timers-for-scheduling-tasks/
|
||||
|
||||
作者：[Richard England][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://fedoramagazine.org/author/rlengland/
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://fedoramagazine.org/wp-content/uploads/2021/06/schedule_with_systemd_timer-816x345.jpg
|
||||
[2]: https://www.freedesktop.org/software/systemd/man/systemd.time.html#Calendar%20Events
|
||||
[3]: https://fedoramagazine.org/what-is-an-init-system/
|
||||
[4]: https://opensource.com/article/20/7/systemd-timers
|
||||
[5]: https://docs.fedoraproject.org/en-US/quick-docs/understanding-and-administering-systemd/
|
||||
227
translated/tech/20210618 Systemd Timers for Scheduling Tasks.md
Normal file
227
translated/tech/20210618 Systemd Timers for Scheduling Tasks.md
Normal file
@ -0,0 +1,227 @@
|
||||
[#]: subject: (Systemd Timers for Scheduling Tasks)
|
||||
[#]: via: (https://fedoramagazine.org/systemd-timers-for-scheduling-tasks/)
|
||||
[#]: author: (Richard England https://fedoramagazine.org/author/rlengland/)
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: (dcoliversun)
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
|
||||
用于调度任务的 Systemd 定时器
|
||||
======
|
||||
|
||||
![][1]
|
||||
|
||||
Systemd 提供定时器有一段时间了，定时器替代了 _cron_ 功能，这一特性值得看看。本文将向你介绍在系统启动后如何使用 _systemd_ 中的定时器来运行任务，此后重复运行。这不是对 _systemd_ 的全面讨论，只是介绍这一特性。
|
||||
|
||||
### Cron、anacron 与 systemd：快速回顾
|
||||
|
||||
_Cron_ 可以将任务调度以几分钟到几个月或更长时间的粒度运行。设置起来相对简单，只需要一个配置文件。虽然配置过程有些深奥，但一般用户也可以使用。
|
||||
|
||||
|
||||
然而，如果您的系统在需要执行的时间没有运行，那么 _Cron_ 会失败。
|
||||
|
||||
_Anacron_ 克服了“系统不运行”问题。它确保你的系统再次启动时，任务将执行。虽然它旨在管理员使用，但有些系统允许普通用户访问 _Anacron_。
|
||||
|
||||
但是，_anacron_ 的执行频率不能低于每天一次。
|
||||
|
||||
_cron_ 和 _anacron_ 都存在执行上下文一致性的问题。必须注意任务运行时有效的环境与测试时使用的环境完全相同。必须提供相同的 shell、环境变量和路径。这意味着测试和调试有时会很困难。
|
||||
|
||||
_Systemd_ 定时器提供了 _cron_ 和 _anacron_ 的优点，允许调度到分钟粒度。确保在系统再次运行时执行任务，即使在预期的执行时间内任务处于关闭状态。对所有用户都可用。你可以在它将要运行的环境中测试和调试执行。
|
||||
|
||||
但是，配置更加复杂，至少需要两个配置文件。
|
||||
|
||||
如果你的 _cron_ and _anacron_ 配置很好地为你服务，那么可能没有理由改变。但是 _systemd_ 至少值得研究，因为它可以简化任何当前的 _cron_/_anacron_ 工作方式。
|
||||
|
||||
### 配置
|
||||
|
||||
_Systemd_ 定时器执行的函数至少需要两个文件。这两个是“<ruby>定时器<rt>timer unit</rt></ruby>”和“<ruby>系统服务<rt>service unit</rt></ruby>”。动作不仅仅是简单的命令，你还需要一个“作业”文件或脚本来执行必要的功能。
|
||||
|
||||
定时器文件定义调度表，而系统服务文件定义执行的任务。有关的更多详细信息参考 “man systemd.timer” 中提供的 .timer unit。服务单元的详细信息可在 “man systemd.service” 中找到。
|
||||
|
||||
There are several locations where unit files exist (listed in the man page). Perhaps the easiest location for the general user, however, is “~/.config/systemd/user”. Note that “user” here, is the literal string “user”.
|
||||
单元文件存在于几个位置(在 man page 中列出)。然而，对于普通用户来说，最容易找到的位置可能是 “~/.config/systemd/user”。请注意，这里的“用户”是字符串“用户”。
|
||||
|
||||
### 示例
|
||||
|
||||
此示例是一个创建用户调度作业而不是系统调度作业(以root用户身份运行)的简单示例。它将消息、日期和时间打印到文件中。
|
||||
|
||||
|
||||
1. 首先创建一个执行任务的 shell 脚本。在你的本地 “bin” 目录中创建它，例如在 “~/bin/schedule-test.sh” 中。
|
||||
|
||||
创建文件：
|
||||
|
||||
```
|
||||
touch ~/bin/schedule-test.sh
|
||||
```
|
||||
|
||||
然后将以下内容添加到你刚刚创建的文件中。
|
||||
|
||||
```
|
||||
#!/bin/sh
|
||||
echo "This is only a test: $(date)" >> "$HOME/schedule-test-output.txt"
|
||||
```
|
||||
|
||||
记住赋予你的 shell 脚本执行权限。
|
||||
|
||||
2. 创建 .service 调用上面的脚本。在以下位置创建目录与文件：“~/.config/systemd/user/schedule-test.service
|
||||
|
||||
|
||||
|
||||
```
|
||||
[Unit]
|
||||
Description=A job to test the systemd scheduler
|
||||
|
||||
[Service]
|
||||
Type=simple
|
||||
ExecStart=/home/<user>/bin/schedule-test.sh
|
||||
|
||||
[Install]
|
||||
WantedBy=default.target
|
||||
```
|
||||
|
||||
请注意<用户>应该是你的 @HOME 地址，但是资源文件路径名中的“用户”实际上是字符串“用户”。
|
||||
|
||||
_ExecStart_ 应该提供一个没有变量的绝对地址。例外情况是，对于 _用户_，您可以用 “%h” 替换 $HOME。换句话说，你可以使用:
|
||||
|
||||
```
|
||||
ExecStart=%h/bin/schedule-test.sh
|
||||
```
|
||||
|
||||
这仅用于用户文件。这不适用于系统服务，因为在系统环境中运行时 “%h” 总是返回 “/root”。其他替换可在“说明符”下的 “man systemd.unit” 中找到。因为它超出了本文的范围，所以这就是我们目前需要了解的关于说明符的全部内容。
|
||||
|
||||
3\. 创建一个 .timer 文件，该文件实际上调度你创建的 .service。在 .service 文件相同位置 “~/.config/systemd/user/schedule-test.timer” 创建它。请注意，文件名仅在拓展名上有所不同，例如一个是 “.service”，一个是 ".timer"。
|
||||
|
||||
```
|
||||
[Unit]
|
||||
Description=Schedule a message every 1 minute
|
||||
RefuseManualStart=no # Allow manual starts
|
||||
RefuseManualStop=no # Allow manual stops
|
||||
|
||||
[Timer]
|
||||
#Execute job if it missed a run due to machine being off
|
||||
Persistent=true
|
||||
#Run 120 seconds after boot for the first time
|
||||
OnBootSec=120
|
||||
#Run every 1 minute thereafter
|
||||
OnUnitActiveSec=60
|
||||
#File describing job to execute
|
||||
Unit=schedule-test.service
|
||||
|
||||
[Install]
|
||||
WantedBy=timers.target
|
||||
```
|
||||
|
||||
请注意，.timer 文件使用了 “OnUnitActiveSec” 来指定调度表。“OnCalendar” 选项更加灵活。例如:
|
||||
|
||||
|
||||
```
|
||||
# run on the minute of every minute every hour of every day
|
||||
OnCalendar=*-*-* *:*:00
|
||||
# run on the hour of every hour of every day
|
||||
OnCalendar=*-*-* *:00:00
|
||||
# run every day
|
||||
OnCalendar=*-*-* 00:00:00
|
||||
# run 11:12:13 of the first or fifth day of any month of the year
|
||||
# 2012, but only if that day is a Thursday or Friday
|
||||
OnCalendar=Thu,Fri 2012-*-1,5 11:12:13
|
||||
```
|
||||
|
||||
有关 “OnCalendar” 的更多信息参见[这里][2]。
|
||||
|
||||
4\. 所有的部件都已就位，但你应该进行测试，以确保一切正常。首先，启用用户服务:
|
||||
|
||||
```
|
||||
$ systemctl --user enable schedule-test.service
|
||||
```
|
||||
|
||||
这将导致类似如下的输出:
|
||||
|
||||
```
|
||||
Created symlink /home/<user>/.config/systemd/user/default.target.wants/schedule-test.service → /home/<user>/.config/systemd/user/schedule-test.service.
|
||||
```
|
||||
|
||||
现在执行测试工作：
|
||||
|
||||
```
|
||||
$ systemctl --user start schedule-test.service
|
||||
```
|
||||
|
||||
检查你的输出文件($HOME/schedule-test-output.txt)，确保你的脚本运行正常。应该只有一个条目，因为我们还没有启动定时器。必要时进行调试。如果你需要更改 .service 文件，而不是更改它调用的 shell 脚本，请不要忘记再次启用该服务。
|
||||
|
||||
5\. 一旦作业正常运行，通过为服务启用、启动用户定时器来实时调度作业:
|
||||
|
||||
```
|
||||
$ systemctl --user enable schedule-test.timer
|
||||
$ systemctl --user start schedule-test.timer
|
||||
```
|
||||
|
||||
请注意，你已经在上面的步骤4中启动、启用了服务，因此只需要为它启用、启动定时器。
|
||||
|
||||
启用命令会产生如下输出：
|
||||
|
||||
```
|
||||
Created symlink /home/<user>/.config/systemd/user/timers.target.wants/schedule-test.timer → /home/<user>/.config/systemd/user/schedule-test.timer.
|
||||
```
|
||||
|
||||
启动命令将返回命令行界面提示。
|
||||
|
||||
|
||||
### 其他操作
|
||||
|
||||
你可以检查和监控服务。如果你从系统服务收到错误，下面的第一个命令特别有用：
|
||||
|
||||
```
|
||||
$ systemctl --user status schedule-test
|
||||
$ systemctl --user list-unit-files
|
||||
```
|
||||
|
||||
手动停止服务：
|
||||
|
||||
```
|
||||
$ systemctl --user stop schedule-test.service
|
||||
```
|
||||
|
||||
永久停止并禁用定时器和服务，重新加载守护程序配置并重置任何失败通知：
|
||||
|
||||
```
|
||||
$ systemctl --user stop schedule-test.timer
|
||||
$ systemctl --user disable schedule-test.timer
|
||||
$ systemctl --user stop schedule-test.service
|
||||
$ systemctl --user disable schedule-test.service
|
||||
$ systemctl --user daemon-reload
|
||||
$ systemctl --user reset-failed
|
||||
```
|
||||
|
||||
### 总结
|
||||
|
||||
本文以 _systemd_ 定时器为出发点，但是 _systemd_ 的内容远不止于此。这篇文章应该为你提供一个基础。你可以从[Fedora Magazine systemd系列][3]开始探索更多。
|
||||
|
||||
参考 —— 更多阅读：
|
||||
|
||||
* man systemd.timer
|
||||
* man systemd.service
|
||||
* [Use systemd timers instead of cronjobs][4]
|
||||
* [Understanding and administering systemd][5]
|
||||
* <https://opensource.com/> 内有 systemd 快捷查询列表
|
||||
|
||||
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://fedoramagazine.org/systemd-timers-for-scheduling-tasks/
|
||||
|
||||
作者：[Richard England][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[dcoliversun](https://github.com/dcoliversun)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://fedoramagazine.org/author/rlengland/
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://fedoramagazine.org/wp-content/uploads/2021/06/schedule_with_systemd_timer-816x345.jpg
|
||||
[2]: https://www.freedesktop.org/software/systemd/man/systemd.time.html#Calendar%20Events
|
||||
[3]: https://fedoramagazine.org/what-is-an-init-system/
|
||||
[4]: https://opensource.com/article/20/7/systemd-timers
|
||||
[5]: https://docs.fedoraproject.org/en-US/quick-docs/understanding-and-administering-systemd/
|
||||
Loading…
Reference in New Issue
Block a user