What is LightDM and GDM? In Linux operating system I heard both but I don't know about them and what is called? Where they are used? Are they related to display?


LightDM is an x display manager that aims to be lightweight, fast, extensible and multi-desktop. It uses various front-ends to draw login interfaces, so-called Greeters.

Key features are:

  • A well-defined greeter API allowing multiple GUIs
  • Support for all display manager use cases, with plugins where appropriate
  • Low code complexity
  • Fast performance


LightDM offers at least the same functionality as GDM but it has a simpler code base and does not load any GNOME libraries to work. LightDM is the default display manager for Ubuntu.

LighDM configuration is governed by the configuration files in /etc/lightdm/lightdm.conf.d/. To add your own configuration, create a new file in that directory such as /etc/lightdm/lightdm.conf.d/my.conf.

GDM (the GNOME Display Manager) is a display manager (a graphical login program) for the windowing systems X11 and Wayland.It is a highly configurable reimplementation of xdm, the X Display Manager.


Gdm allows you to log into your system with the X Window System running and supports running several different X sessions on your local machine at the same time.

The X Window System by default uses the XDM display manager. However, resolving XDM configuration issues typically involves editing a configuration file. GDM allows users to customize or troubleshoot settings without having to resort to a command line.

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