How To Find Your Currently Active Display Manager In Linux

Sometimes, you might need to know which display manager your Linux system is using, especially if you’re fixing login problems or changing how your system looks. In this post, we'll show you simple ways to find your active display manager in Linux.

What is a Display Manager?

If you use Linux, you’ve probably seen the login screen when you start your computer. The program that shows this screen is called a Display Manager. It helps you log into your desktop environment, like GNOME or KDE.

A display manager is a program that handles graphical logins. It shows the login screen and starts your desktop environment after you log in.

It is not the same as a desktop environment. For example:

• GNOME is a desktop environment.
• GDM (GNOME Display Manager) is the display manager that starts GNOME.

You can think of the display manager as the "gatekeeper" for your graphical session.

In most Linux contexts, “display manager” and “login manager” are used interchangeably, especially in everyday conversation or beginner guides. They both refer to the same thing.

Common Linux Display Managers

Here are some of the most common display managers:

• GDM (GNOME Display Manager): Used by GNOME.
• LightDM: A lightweight choice, used by Ubuntu (earlier versions), XFCE, and MATE.
• SDDM (Simple Desktop Display Manager): Used by KDE Plasma.
• LXDM: For the LXDE desktop.
• XDM, MDM: Older or less common options.

Methods to Identify Currently Active Display Manager

Let’s walk through different ways to find your current display manager. These methods mostly use the terminal, but it's not that difficult.

Method 1: Using systemctl (Most Reliable)

If your system uses systemd (most modern Linux distributions do), try this:

systemctl status display-manager

Look for lines that mention something like:

Loaded: loaded (/lib/systemd/system/lightdm.service; enabled)
Active: active (running)

The above output tells you LightDM is running. You might also see GDM, SDDM, or LXDM.

You can also try checking specific ones:

systemctl status gdm
systemctl status lightdm
systemctl status sddm

If one of them is active, that’s your display manager.

Method 2: Check Configuration Files

Some Linux systems have files that show which display manager is set by default.

Try this:

cat /etc/X11/default-display-manager

You might see something like:

/usr/sbin/lightdm

Another way is to check this file (for systemd systems):

cat /etc/systemd/system/display-manager.service

It may show a symbolic link pointing to the active display manager’s service.

Sample Output:

[Unit]
Description=Light Display Manager
Documentation=man:lightdm(1)
After=systemd-user-sessions.service

# replaces plymouth-quit since lightdm quits plymouth on its own
Conflicts=plymouth-quit.service
After=plymouth-quit.service

# lightdm takes responsibility for stopping plymouth, so if it fails
# for any reason, make sure plymouth still stops
OnFailure=plymouth-quit.service

[Service]
ExecStart=/usr/sbin/lightdm
Restart=always
BusName=org.freedesktop.DisplayManager

[Install]
Alias=display-manager.service

Method 3: Use ps to Check Running Processes

This method looks for display manager programs running in the background.

Run this command:

ps aux | grep -E 'dm|gdm|lightdm|sddm|lxdm'

Look at the names in the results. For example:

/usr/sbin/gdm3

This means GDM is running.

Method 4: Use a Graphical Tool (If Available)

In some desktop environments, you might find this info under "About This System" or "Login Screen" settings. But since this isn’t always available or consistent, the command-line methods above are more reliable.

Why You Need to Know Your Active Display Manager

Here are a few reasons this info is useful:

• Fixing login problems – Sometimes the display manager fails, and knowing which one is running helps you troubleshoot.
• Changing the look – Many display managers support themes and greeter settings.
• Trying a new one – You might want to switch to a different display manager.
• Learning more – Understanding your Linux system helps you get better at using it.

How to Change Your Display Manager

If you decide to change your display manager, here’s how to do it on Debian or Ubuntu-based systems:

sudo dpkg-reconfigure gdm3

Replace gdm3 with the name of the display manager you want to use (like lightdm or sddm).

For systems using systemd, you can also use:

sudo systemctl disable gdm
sudo systemctl enable lightdm
sudo systemctl start lightdm

Only do this if you know what you’re doing. Always install the new display manager before switching.

Conclusion

Now you know how to check your currently active display manager in Linux using simple terminal commands. This is useful for troubleshooting, customization, or just understanding your Linux system better.

Use any method that suits best for you to identify the active display manager in your Linux machine.