就会报如下错误：
[root@abc]# systemctl restart auditd
Failed to restart auditd.service: Operation refused, unit auditd.service may be requested by dependency only
因为我并没有编辑过/usr/lib/systemd/system/auditd.service 下的文件，所以不是人为修改导致服务重启失败，经过GOOGLE大神的帮助，终于找到了如下答复：原文如下：
The audit daemon must be controlled from the service command. It will decide which commands can be sent to systemctl and which ones are supported by legacy actions. So, you should do:
service auditd restart
Unfortunately, it has to be this way.
既然Steve Grubb 都不能解决这个问题，看来有些古老应用还是需要service 这种传统方式才能解决呀。