Monit is a free open source utility for managing and monitoring, processes, files, directories and filesystems on a UNIX system. Monit conducts automatic maintenance and repair and can execute meaningful causal actions in error situations. (unofficial mirror)
Hi! Look at my question at https://stackoverflow.com/questions/52164129/what-am-i-doing-wrong-in-monit-syntax-with-regex/52216995.
It seems there is issues in docs at least for "check file" instructions.