How to Uninstall or Remove gdm3 Software Package from Ubuntu 24

Ubuntu is a versatile operating system that offers several display managers to suit various needs. One of the most popular display managers is gdm3 (GNOME Display Manager), the default for GNOME-based desktops. However, there might be scenarios where you need to remove gdm3 — such as transitioning to a lightweight display manager like lightdm or deploying a headless server setup.

In this blog, we'll guide you through the steps to safely uninstall gdm3 from Ubuntu 24 and discuss whether removing it is ever necessary for a production server.

Why Remove gdm3?

Removing gdm3 is rarely necessary in a production environment unless the system is explicitly configured for:

Headless Operation: If your production server does not require a graphical user interface (GUI), uninstalling gdm3 reduces resource usage and attack surface, improving performance and security.
Switching Display Managers: For use cases requiring lighter alternatives such as lightdm or sddm, removing gdm3 avoids conflicts.

Note: If you're using Ubuntu in a server-only setup, graphical environments are generally discouraged in production as they consume unnecessary resources.

Prerequisites

Before proceeding, ensure you have:

Root or sudo access to the server.
Backup of critical data to avoid accidental misconfiguration.
An alternative display manager installed (if you’re not using a headless setup).

Step-by-Step Guide to Remove gdm3

1. Check Your Current Display Manager

Run the following command to identify the current display manager:

cat /etc/X11/default-display-manager

If the output is /usr/sbin/gdm3, it indicates that gdm3 is active.

2. Install an Alternative (Optional)

If you're planning to switch to another display manager, such as lightdm, install it first:

sudo apt update

sudo apt install lightdm

During installation, you’ll be prompted to select the default display manager. Use the arrow keys to highlight lightdm and press Enter.

3. Disable gdm3

To disable gdm3 temporarily:

sudo systemctl disable gdm3

If you’ve installed an alternative display manager, enable it:

sudo systemctl enable lightdm

sudo systemctl start lightdm

4. Uninstall gdm3

Once you’ve verified that an alternative display manager is active, remove gdm3:

sudo apt remove --purge gdm3

The --purge option ensures configuration files are also removed. If you prefer to retain the configuration files, omit this flag.

5. Remove Unused Dependencies

After removing gdm3, clean up any unnecessary dependencies:

sudo apt autoremove

6. Reboot the System

Finally, restart your system to ensure the changes take effect:

sudo reboot

Testing Your Setup

If you switched to another display manager, ensure it starts correctly and allows user login.
For headless setups, confirm remote access (e.g., SSH) is functional.
Use systemctl to verify that no unnecessary display manager services are running.

Conclusion

Uninstalling gdm3 can streamline server performance in production environments by eliminating the overhead of a GUI. However, in most cases, production servers should not include graphical components unless absolutely necessary. If you’re operating a headless server, removing gdm3 contributes to better security and efficiency. For desktop users, switching to a lighter alternative like lightdm can optimize system performance.

Always proceed cautiously, ensuring that an alternative display manager or remote management capability is in place before removing gdm3.