PLugin to check status of local service

I am trying to find a plugin that will check the status of a service in Linux. Say for example /etc/init.d/nfs status. If it returns as running it is OK. If it returns as stopped it is Critical. Anyone know of any plugins to do this? I am not sure how to write one so I haven’t been able to do that either.

I am still looking for an answer to this if anyone has any ideas.