% systemd, systemctl, units
# List loaded Units
systemctl list-units --type <units-type> --state <units-state> --<scope>
$ units-type: printf '%s\n' service timer socket target automount mount device path scope slice swap
$ units-state: printf '%s\n' running inactive waiting failed error
$ scope: printf '%s\n' user system all

# List Unit Files
systemctl list-unit-files --type <units-type> --state <unit-file-state> --<scope>
$ units-type: printf '%s\n' service timer socket target automount mount device path scope slice swap
$ unit-file-state: printf '%s\n' enabled disabled masked
$ scope: printf '%s\n' user system all