Reprinted from: http://blog.csdn.net/qq229596421/article/details/72084693
sudo vi /etc/default/grub
#GRUB_CMDLINE_LINUX_DEFAULT=”quiet”
GRUB_CMDLINE_LINUX=”text”
GRUB_TERMINAL=console
sudo update-grub
sudo systemctl set-default multi-user.target
sudo reboot
After entering the command line mode, you can switch back to the desktop mode with the following command
sudo systemctl start lightdm