This is about working with targets. Other aspects of systemctl.
systemctl list-units --type=target
systemctl list-unit-files --type=target
Display the default target
By default, the
systemd process uses the default target when booting the
system. To view the default target on your system:
To set a different target as a default target, e.g.
sudo systemctl set-default graphical.target
Change the current active target
To change the current active target immediately, e.g. to switch from the current graphical target (GUI) to the multi-user target (CLI):
sudo systemctl isolate multi-user.target
Boot the system in Single User mode
If your system unable to complete a regular boot, you can boot it into the rescue (single-user) mode for further troubleshooting.
sudo systemctl rescue
In rescue mode the system tries to mount all the local file systems and start only few important system services, but it does not activate network interfaces or allow more users to log into the system at the same time.
Boot the system in Emergency mode
If the Rescue/Single User mode does not boot, try Emergency mode.
In emergency mode, the system mounts the root file system for read-only purposes and does not attempt to load any other local file systems. Network interfaces are not activated. Only essential services are started.
sudo systemctl emergency
systemctl also allows users to
reboot a system.
sudo systemctl halt
sudo systemctl poweroff
$ sudo systemctl reboot