check_maintenance allows you to let Nagios do the critical check, if the
hardware of a given host is still in service or not.

check_maintenance will read the given file with maintenance data and checks for
a line with the given hostname and service date.

If it succeeds, the service date will be processed against the given warning
and critical values.

All data in the maintenance file behind the second '|' will be printed as
normal output to Nagios, so you can use this to add addtional informations like
the room or inventory number of the host.