Ubuntu 16.04服务器上的网站好久没管，今天发现不能访问了，后来发现是rc-local服务无法启动所致：

运行sudo systemctl status rc-local.service提示如下：

Aug 03 15:06:37 iZj6c99xhx1fk9qwp5lbd9Z rc.local[1187]: /opt/lampp/mysql/scripts/ctl.sh : mysql  could not be started

Aug 03 15:06:37 iZj6c99xhx1fk9qwp5lbd9Z systemd[1]: rc-local.service: Control process exited, code=exited status=3

Aug 03 15:06:37 iZj6c99xhx1fk9qwp5lbd9Z systemd[1]: Failed to start /etc/rc.local Compatibility.

Aug 03 15:06:37 iZj6c99xhx1fk9qwp5lbd9Z systemd[1]: rc-local.service: Unit entered failed state.

Aug 03 15:06:37 iZj6c99xhx1fk9qwp5lbd9Z systemd[1]: rc-local.service: Failed with result 'exit-code'.

百度搜答案，找到《ubuntu16.04 程序开机自启动设置及启动优化》一文，得知应该在/etc/rc.local的最后一行exit 0的上一行末尾加上&才行。如下所示：

#!/bin/sh -e

/home/stallmanist/the_commander.sh &

exit 0

经测试，成功。