systemd examples

see which systemd startup targets are available and what the current default target is

# systemctl list-units --type target --all
# systemctl get-default

switch from graphical gui startup target to multi user text startup target on next boot

# systemctl set-default multi-user.target

and to switch to gui startup target on next boot

# systemctl set-default graphical.target

disable apache and php fpm from starting on next boot

# systemctl list-units --type service | grep -e "apache|fpm"
# systemctl disable apache2.service
# systemctl disable php7.0-fpm.service