Frequently Asked Question

What is systemctl and what are its essential commands?

systemctl is the main command-line client for talking to systemd. Nearly everything a sysadmin used to do by editing init scripts is now a systemctl verb. The core verbs come in pairs: start/stop (act now), enable/disable (act at boot), restart/ reload (apply changes), and the inspection verbs status, is-active, and is-enabled. The convenient systemctl enable --now <unit> enables a unit at boot and starts it immediately in one step.

Beyond per-unit verbs there are listing commands, systemctl list-units shows what is currently loaded, list-unit-files shows every unit known on disk, and --failed narrows to units that have died. systemctl daemon-reload tells systemd to re-read unit files after you have edited them on disk; forgetting this step is the most common reason a freshly edited unit file appears to have no effect.