转自 ：https://m635674608.iteye.com/blog/2359480
1.
#systemctl enable crond.service //让某个服务开机启动(.service可以省略)
#systemctl disable crond.service //不让开机启动
#systemctl status crond.service //查看服务状态
#systemctl start crond.service //启动某个服务
#systemctl stop crond.service //停止某个服务
#systemctl restart crond.service //重启某个服务
#systemctl is-enabled crond //查看某个服务是否开机启动