How to change display manager for Ubuntu, Kubuntu or Debian

In a Linux system, the display manager controls the graphical user interface (GUI) session after user login. Ubuntu uses GDM3 by default, while Kubuntu uses SDDM. Other options like LightDM and XDM are also available, each with different features. Changing the display manager is common when users switch desktop environments or seek performance improvements.

Switching the display manager in Ubuntu is straightforward. The process uses tools like apt and dpkg-reconfigure. When a new display manager is installed, the system allows users to choose their preferred manager. This customization helps align the login experience with the user's desktop environment and system requirements.

On Debian-based systems, including Ubuntu, the dpkg-reconfigure command is essential for selecting and configuring the display manager. The process involves checking the current manager, selecting a new one, and rebooting the system. This ensures a smooth transition and enhances the login experience by matching it to personal or system needs.

1. Open the terminal.
2. Check the current display manager using systemctl.
3. Install your desired display manager if it's not already installed.
4. Use dpkg-reconfigure to configure default desktop manager.

   $ sudo dpkg-reconfigure gdm3
   [sudo] password for user: 

   Replace gdm3 with the display manager you want to use. For example, sddm for Kubuntu.

   systemctl will gracefully exit if no other display manager is installed.

   

5. Use arrow key to select your preferred display manager, use <tab> key to navigate to the Ok button and press [ENTER].

   Use <tab> key to navigate to the Ok button and press [ENTER] if you're first presented with the following screen. You'll get this screen if you're using a low resolution monitor and/or not running terminal in full screen.

6. Reboot the system to apply the changes.