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Systemd Systemctl a Poem

systemctl is systemd for system control
start is systemctl command to start an application
stop is systemctl command to stop an application
reload reloads files for configuration
restart starts application again if no reload
reload-or-restart restarts if cannot reload
enable makes systemd start services automatically
disable stops services from starting automatically
status prints what the application is doing magically
is-active, is-enabled, is-failed checks specific states
list-units gives a list of currently active units
systemctl by itself does the same as list-units
cat is used to display a unit file

See https://www.digitalocean.com/community/tutorials/how-to-use-systemctl-to-manage-systemd-services-and-units