關(guān)閉開機自啟動：
#sudo systemctl disable lightdm.service
Synchronizing state of lightdm.service with SysV service script with /lib/systemd/systemd-sysv-install.
Executing: /lib/systemd/systemd-sysv-install disable lightdm
Removed /etc/systemd/system/display-manager.service.
添加自動啟動：
sudo ln -s /lib/systemd/system/lightdm.service?/etc/systemd/system/display-manager.service?
手動啟動：
sudo service lightdm start
