Nagios plugin to check the system state according to systemd. This plugin checks the system's state according to systemd, i.e.
$ systemctl is-system-running
degraded
If it reports anything other than "running", be sure to check the output of these commands:
$ systemctl list-units
$ systemctl status
Requires python3-dbus.
License: Public Domain. Keep my name in it if you like. Author: Mike Gerber 2015, 2016, 2021