Description:

"mon" is a tool for monitoring the availability of services. Services
may be network-related, environmental conditions, or nearly anything
that can be tested with software. It is extremely useful for system
administrators, but not limited to use by them. It was designed to be a
general-purpose problem alerting system, separating the tasks of
testing services for availability and sending alerts when things fail.
To achieve this, "mon" is implemented as a scheduler which runs the
programs which do the testing, and triggering alert programs when these
scripts detect failure. None of the actual service testing or
reporting is actually handled by "mon". These functions are handled by
auxillary programs.