方法一：rc.local

• 最简单且比较常用的方法是在/etc/rc.local（/etc/rc.d/rc.local）文件中添加脚本，该脚本会在启动时被调用，如此以来就能实现随机启动的目的

方法二：systemctl

• systemctl是linux操作系统的系统控制器，他可以管理系统的各种服务，其实方法一的本质是在systemctl中注册了一个rc-local.service的服务，这个服务中会调用/etc/rc.local中的脚本，然后这个服务会随机启动

• 如何注册一个systemctl服务？只要在/etc/systemd/system目录下创建一个xxx.service的文件即可，我们看看rc-local.service是如何编写的

  #  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.d/rc.local is executable.
  [Unit]
  Description=/etc/rc.d/rc.local Compatibility
  Documentation=man:systemd-rc-local-generator(8)
  ConditionFileIsExecutable=/etc/rc.d/rc.local
  After=network.target
  
  [Service]
  Type=forking
  ExecStart=/etc/rc.d/rc.local start
  TimeoutStartSec=0
  TimeoutStopSec=30
  RemainAfterExit=yes
  GuessMainPID=no
  

• 最基本最简单的service文件

  [Service]
  Type=forking
  ExecStart=/...
  [Install]
  WantedBy=multi-user.target
  

• 设置好了service文件后，需要随机启动还需要执行一行命令

  ~:$ systemctl enable xxx