What is Display Manager on Linux?

One convertible component that is often overlooked is the Display Manager. But what is this ingredient? How do I switch to the new Display Manager in Linux? Let's find out with make tech.

What is Display Manager?

Also known as the 'login manager', Display Manager is responsible for starting up the display server and loading the monitor. This happens as soon as you enter your username and password correctly.

In simple terms, it controls user sessions and manages user authentication. Most of Display Manager work happens in the background. The only visible element is the login window, sometimes called a 'greeter'.

Display Manager is not?

You probably already know that Linux computers have a window manager and a display server.

Display Manager is a separate software. While all three are interactive, they function differently and perform different jobs.

Example of window manager:

1. KWin
2. Openbox
3. Dwm

Some well-known Linux display servers:

1. Wayland
2. Mir
3. Org

Some display managers:

1. GDM (Gnome Display Manager)
2. LightDM
3. LXDM

Why should Display Manager be replaced?

Why would people want to replace display manager? Here are a few possible scenarios:

You are trying to use an old PC and need a lightweight display manager.

Your current Display manager crashed after updating and installing another one would be much faster than switching to another Linux distro.

You want to apply beautiful themes to your login window, but the default display manager of your distribution is limited in this respect.

There are several popular display managers available for Linux. You will notice that they are quite similar in design; The main differences are in size, complexity, and how they manage users and sessions.

Popular display managers you can switch

With the new display manager installed, you can play around with its themes. MDM is the best choice if customization is your priority, as it supports both old GDM and new HTML themes. DeviantART has a large collection of themes for different display managers. If you're using SDDM, you can find theme packages in the archive.

But first, which display manager should you switch to?

1. KDM

Display Manager for KDE up to KDE Plasma 5, KDM has many customization options. You can easily configure it via the control module in System Settings. There, you can choose a KDM theme to use or switch to a simple greeter that allows you to customize the background, greeting, and font.

What is Display Manager on Linux? Picture 1

Other features include:

1. Quick user change
2. Show list of users
3. Activate power off
4. Allow login without password
5. Automatic login
6. Fingerprint scan

KDM supports X and Wayland, can also detect installed desktop environments and window manager. They then provide a list for you to choose which one you should use when entering your credentials.

While some of the features may be overwhelming for beginners, KDM is easy to set up thanks to the simple graphical dialog.

2. GDM (GNOME Display Manager)

KDM is for KDE, similar to GDM3 for GNOME - the default display for popular Linux desktop environments. Like KDM, it supports X and Wayland, functions include:

1. Automatic login
2. Hide user list
3. Login without password
4. Modify sessions
5. Built-in themes
6. Allows users
7. Quick session change
8. Fingerprint scanning supported
9. Smart card validation

What is Display Manager on Linux? Picture 2

GDM3 configuration can be done through dedicated dialog box in System Settings or by editing configuration file.

Note that GDM3 is different from the old GDM. Although they seem the same, GDM3 is not backward compatible with old GDM themes, with options hidden in the configuration file.

3. SDDM (Simple Desktop Display Manager)

SDDM is a new display manager. First released in 2013, it still exists, while older competitors like SLiM and Mint Display Manager have to offer.

Support for X and Wayland, SDDM based on QML theme and replacing KDM as the default display manager in KDE Plasma 5.

What is Display Manager on Linux? Picture 3

The functions of SDDM include:

1. Automatic login
2. Turn on number lock
3. Edit user greeter
4. Supports many themes

As with other simple display managers, you can configure SDDM by editing the configuration file (sddm.conf). If you are using SDDM over KDE, it has a configuration module in System Settings.

4. LXDM

LXDM is part of the LXDE environment but runs comfortably on other desktop environments because it doesn't have a lot of dependencies. You can set it up through its own configuration utility or edit the configuration files in / etc / lxdm (or if you are using Lubuntu, / etc / xdg / lubuntu / lxdm).

What is Display Manager on Linux? Picture 4

Functions available on LXDM:

1. Configurable user list
2. Automatic login
3. Separate icons for each user
4. Change user
5. Timer automatically login
6. Change background image

Both the official documentation and the unofficial accounts on the various forums note that LXDM does not terminate user processes upon logout. To make sure this happens, modify the / etc / lxdm / PostLogout file.

5. LightDM

The most popular is undoubtedly the LightDM display manager. It's customizable and feature packed, LightDM is also lightweight, supports X.Org and Mir.

What is Display Manager on Linux? Picture 5

LightDM functions:

1. Greeter for GTK, Qt / KDE, Unity and other greeters
2. Many login screen themes
3. User list
4. Change background image
5. The window position is changeable

Configuration files should be made according to these tweaks - the easiest way is the LightDM GTK Greeter Settings tool.

6. XDM

This is the default display manager for X Window System and was first released in 1988. It is a minimalistic display manager suitable for low spec systems or those with no high requirements.

What is Display Manager on Linux? Picture 6

Even so, XDM still has the following features:

1. Many topics
2. Installing wallpaper
3. Edit fonts
4. Adjust the login frame position
5. Handling multiple X sessions
6. Login without password

Most of the settings are applied by editing etc / X11 / xdm / Xresources.

Micah Soto

Update 19 August 2020