Systemctl

• status [Servicename] Show the current status (q to quit)
• start [Servicename] Runs the unit once
• enable [Servicename] Will always run the unit on boot

Journald

• journalctl --vacuum-time=2d //keep the last 2 days
• journalctl --vacuum-size=500M //keep 500 megabytes
• -f //Show a live view
• -u[Unitname] //Limit the view to a specific unit
• -e //Start at the start of the journal