root@zelkoa:/home/bagou450# systemctl --state=failed
  UNIT                           LOAD   ACTIVE SUB    DESCRIPTION
● systemd-networkd-wait-online.service loaded failed failed Wait for Network to

LOAD   = Reflects whether the unit definition was properly loaded.
ACTIVE = The high-level unit activation state, i.e. generalization of SUB.
SUB    = The low-level unit activation state, values depend on unit type.

1 loaded units listed. Pass --all to see loaded but inactive units, too.
To show all installed unit files use 'systemctl list-unit-files'.