I found something if you mistype some configuration for the Linux. Like set invalid value will cause the System crash.
In my experience. I assign an invalid value for seLinux. The CentOs will not start up. And It is hard to figure out what is it going on. (I nearly want to reinstall the whole system...)
So I wondered if there exists some validator for this kind of configuration. Before you saving the configuration. Basically, It supposed to remind you if there exist the wrong invalid value out there .