Get default target (runlevel)
systemctl get-default
List all targets (runlevels)
systemctl --type=target
Set default target (runlevel)
systemctl set-default
List all running services
systemctl --type=service
See service status
systemctl status sshd
Start service
systemctl start sshd
Enable service
systemctl enable sshd
Writing service scripts
http://0pointer.de/blog/projects/systemd-for-admins-3.html
Disable CTRL-ALT-DEL
systemctl mask ctrl-alt-del.target
systemctl daemon-reload