http://www.ruanyifeng.com/blog/2016/03/systemd-tutorial-commands.html
centeros 路径
/usr/lib/systemd/system
ubuntu路径
/lib/systemd/system
http://www.ruanyifeng.com/blog/2016/03/systemd-tutorial-commands.html
/usr/lib/systemd/system
/lib/systemd/system