idiot

ubuntu18.04设置开机执行命令

2020-07-01

前言

  • Ubuntu18.04 默认是没有 /etc/rc.local 这个文件的,需要自己创建
  • systemd 默认读取 /etc/systemd/system 下的配置文件,该目录下的文件会链
  • 接/lib/systemd/system/下的文件。执行 ls /lib/systemd/system 你可以看到有很多启动脚本,其中就有我们需要的 rc.local.service

查看rc.local.service文件内容

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sudo vim /lib/systemd/system/rc.local.service
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#  SPDX-License-Identifier: LGPL-2.1+
#
# This file is part of systemd.
#
# systemd is free software; you can redistribute it and/or modify it
# under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation; either version 2.1 of the License, or
# (at your option) any later version.

# This unit gets pulled automatically into multi-user.target by
# systemd-rc-local-generator if /etc/rc.local is executable.
[Unit]
Description=/etc/rc.local Compatibility
Documentation=man:systemd-rc-local-generator(8)
ConditionFileIsExecutable=/etc/rc.local
After=network.target

[Service]
Type=forking
ExecStart=/etc/rc.local start
TimeoutSec=0
RemainAfterExit=yes
GuessMainPID=no

一般正常的启动文件主要分成三部分

  • [Unit] 段: 启动顺序与依赖关系
  • [Service] 段: 启动行为,如何启动,启动类型
  • [Install] 段: 定义如何安装这个配置文件,即怎样做到开机启动

可以看出,rc.local.service 它少了 Install 段,也就没有定义如何做到开机启动,所以显然这样配置是无效的。 因此我们就需要在后面帮他加上 [Install] 段,可以发现rc.local.service是rc-local.service文件的链接文件,所以我们只需要修改rc-local.service文件即可:

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sudo vim /lib/systemd/system/rc.local.service

添加

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[Install]  
WantedBy=multi-user.target
Alias=rc-local.service

/etc/目录下面创建rc.local文件,赋予执行权限,

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sudo  touch /etc/rc.local
chmod +x /etc/rc.local

/etc/rc.local 文件添加如下内容:

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#!/bin/sh -e
#
# rc.local
#
# This script is executed at the end of each multiuser runlevel.
# Make sure that the script will "exit 0" on success or any other
# value on error.
#
# In order to enable or disable this script just change the execution
# bits.
#
# By default this script does nothing.
echo "测试脚本执行成功" > /usr/local/test.log
exit 0

systemd 默认读取 /etc/systemd/system 下的配置文件,将/lib/systemd/system/rc.local.service 链接到/etc/systemd/system目录

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sudo ln -s /lib/systemd/system/rc.local.service /etc/systemd/system/

不想链接的话也可以直接新建 在/etc/systemd/system下新建rc-local.service文件

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sudo vim /etc/systemd/system/rc-local.service

把以下内容复制到该文件

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[Unit]
Description=/etc/rc.local Compatibility
ConditionPathExists=/etc/rc.local

[Service]
Type=forking
ExecStart=/etc/rc.local start
TimeoutSec=0
StandardOutput=tty
RemainAfterExit=yes
SysVStartPriority=99

[Install]
WantedBy=multi-user.target

启动服务

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sudo systemctl enable rc-local

启动服务并检查状态

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sudo systemctl start rc-local.service
sudo systemctl status rc-local.service

重启后检查test.log文件是否已经存在

参考

https://blog.csdn.net/github_38336924/article/details/98183253 https://www.jianshu.com/p/79d24b4af4e5