systemctl list-units
systemctl status
systemctl restart
systemctl reload
systemctl reload-or-restart
systemctl is-active
systemctl is-failed
systemctl is-enabled
systemctl umask
systemctl cat
systemctl show
systemctl reboot
systemctl poweroff
systemctl hibernate
systemctl hybrid-sleep
systemctl suspend-then-hibernate
#/var/log
journalctl -f --follow
journalctl --output=json-pretty
journalctl -u, --unit=
journalctl --disk-usage
journalctl -g --grep=
# edit a file
systemctl daemon-reload