In this mode, the Ubuntu graphical user interface is not loaded. No graphics drivers are loaded either. Apart from the graphical user interface, all Ubuntu functions are available.

This can be helpful if the graphic driver or the graphical user interface causes problems when booting. This may also be desirable with a real-time system. The latencies of the system are reduced as no resources are used for the graphical user interface. Also the graphic driver cannot bring in any additional jitter.

If you want to boot with only the most basic features of Ubuntu, choose RunLevel 1.

Detailed article

1. sudo nano /etc/default/grub
2. Set these parameters:
   1. GRUB_CMDLINE_LINUX_DEFAULT=„text“
   2. GRUB_TERMINAL=console
3. sudo update-grub
4. sudo systemctl set-default multi-user.target
5. Reboot

1. sudo systemctl set-default graphical.target
2. Reboot

If you want to go even more basic, you can switch to RunLevel 1.