The Heavy Graphical Interface
When you install the desktop version of Ubuntu, it boots directly into a graphical login screen. The software responsible for managing this login screen and subsequently launching the GNOME desktop environment is a display manager called gdm3. It is a heavy, resource-intensive service that requires a significant amount of RAM and CPU power to render the high-resolution graphics and handle user authentication.
If you have repurposed an old laptop into a headless home server, or if you are running a computationally expensive task (like training a machine learning model or running a dedicated game server) and need every last drop of hardware performance, the graphical interface is completely unnecessary. You can disable the display manager from starting automatically, forcing Ubuntu to boot directly into a lightweight, text-only command line interface, thereby freeing up gigabytes of system memory.
How to Disable the Display Manager
You can tell systemd to change the default “target” (runlevel) of your machine from graphical to multi-user.
- Open your Ubuntu Terminal.
- To stop the display manager from loading on the next boot, execute the following command:
sudo systemctl set-default multi-user.target- Restart your computer.
When the machine reboots, it will stop at a black screen with a simple text prompt asking for your username and password. The gdm3 service will remain dormant. If you ever need the graphical interface temporarily without changing the default boot behavior, you can manually start it from the command line by typing sudo systemctl start gdm3.