systemctl list-unit-files --type service
systemctl list-unit-files --type service|grep enabled
systemctl status sshd.service
systemctl list-units --type service --all
systemctl list-units --type service --all|grep running
systemctl get-default
systemctl list-units --type target
systemctl list-units --type target --all
systemctl set-default name.target
systemctl isolate name.target