update systemctl cli guide

pages/linux/systemctl.md

@@ -1,6 +1,6 @@
 # systemctl
 
-> Control the systemd system and service manager.
+> Control the systemd system and service manager. You may need to run with `sudo` prefix to avoid permission denied issues.
 > More information: <https://www.freedesktop.org/software/systemd/man/systemctl.html>.
 
 - Show all running services:
@@ -11,13 +11,9 @@
 
 `systemctl --failed`
 
-- Start/Stop/Restart/Reload a service:
+- Start/Stop/Restart/Reload/Show the status a service:
 
-`systemctl {{start|stop|restart|reload}} {{unit}}`
-
-- Show the status of a unit:
-
-`systemctl status {{unit}}`
+`systemctl {{start|stop|restart|reload|status}} {{unit}}`
 
 - Enable/Disable a unit to be started on bootup:
 
@@ -31,6 +27,10 @@
 
 `systemctl daemon-reload`
 
-- Check if a unit is enabled:
+- Check if a unit is active/enabled/failed:
+
+`systemctl {{is-active|is-enabled|is-failed|}} {{unit}}`
+
+- List all units of service/socket/automount filter by running/failed state:
 
-`systemctl is-enabled {{unit}}`
+`systemctl list-units --type={{service|socket|automount}} --state={{failed|running}}`