Ubuntu 18.04 设置开机自动执行脚本

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

操作步骤

  • /lib/systemd/system/rc-local.service 文件中添加如下代码:
[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,
root@dyjc-bmg:/home/vagrant# touch /etc/rc.local
root@dyjc-bmg:/home/vagrant# chmod +x /etc/rc.local
  • /etc/rc.local 文件添加如下内容:
#!/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.
  
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
root@dyjc-bmg:/home/vagrant# ln -s /lib/systemd/system/rc.local.service /etc/systemd/system/

注意: 一定要将命令添加在 exit 0之前

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