There are two possibilities for monitoring uninterruptible power supplies (UPS): the Network UPS Tools support nearly all standard devices. The
apcupsd daemon is specifically tailored to UPS's from the company APC, described in 7.10 Monitoring UPSs with apcupsd from page 182. The plugin
check_ups included in Nagios only supports the first implementation.
The following rule generally applies: no plugin directly accesses the UPS interface. Rather they rely on a corresponding daemon that monitors the UPS and provides status information. This daemon primarily serves the purpose of shutting down the connected servers in time in case of a power failure. But it also always provides status information, which ...