[monit] Monitor mounts with monit

[Roman]

Hello,

I have a nfs mount and also an external USB hard drive, both of this
resources are mounted. Sometimes it unmounts for I don't know what
reason. How can I check with monit if it is mounted or not, and then
take an action?

I have tried with check filesystem, but monit gives me an error, it
recognizes the check file statement and considers "system" as a file
name, which is very incorrect, it may be a bug.
Can someone help me please?

Thank you.