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LightDM is a cross-desktop display manager. It was built as a relatively light-weight and highly customizable alternative to GDM. It's developed at Canonical by Robert Ancell and all contributors are required to assign their copyright to Canonical through a Contributor License Agreement that allows proprietarization.

LightDM was introduced in Wheezy. It's stable enough for use in the current Stable and Sid.

To install LightDM, install the lightdm package.

System-wide configuration

The LightDM configuration file is found at /etc/lightdm/lightdm.conf. Making a backup of the original configuration file is recommended.

Alternatively, create /etc/lightdm/lightdm.conf.d/ and place your configuration files there.

To change the current default display manager, run

dpkg-reconfigure lightdm

If you're new to LightDM, it's recommended to have GDM, slim or another display manager installed as a backup.

Viewing current configuration

To view effective configuration, run

lightdm --show-config

This will show current settings, with the configuration files these settings were read from.


Install xserver-xephyr. Then, run LightDM as an X application:

lightdm --test-mode --debug

Enable autologin

Look up these lines in lightdm configuration file, uncomment them and customize to your preference.


Enable user list

By default, LightDM is configured so that the user should enter both their login name and password. The login name is considered sensitive information.

It is possible to provide the user with a selection of available user accounts. The most recently used login name will be selected in the list. The user still has to enter their password to login. This provides a useful compromise between security and convenience for a single-user desktop system.

To enable the user list, place the following setting into /etc/lightdm/lightdm.conf.d/01_my.conf:


Change the greeter's background

Debian's LightDM GTK greeter is configured in /etc/lightdm/lightdm-gtk-greeter.conf. There, we may find that the background image points to /usr/share/images/desktop-base/desktop-background, which is a symlink managed by update-alternatives and is also the main desktop background, or we may find (Debian 9 and up) that no value is set in the greeter.conf file.

If the lightdm greeter's background is using the symlink (Debian 8 and below), the best way is to find some images that you like from /usr/share/images/desktop-base/, then use update-alternatives to change the desktop-background group:

update-alternatives --config desktop-background

If not, then edit /etc/lightdm/lightdm-gtk-greeter.conf and place an integer value (to set a color) or a filename of a .png or .svg file to be used as the greeter image in the file, like this:


User configuration

LightDM itself has no user configuration. Once you've authenticated with your username and password, LightDM will run an X session. If you wish to configure your login environment, you must use the configuration files for whichever type of X session your system is configured to use. By default, this will be the Debian Xsession.

The Debian package, unlike the Ubuntu one, does not contain the /usr/bin/lightdm-session script loading EnvironmentVariables from ~/.profile and other similar files. To get behavior similar to GDM and SDDM override the session-wrapper setting with a script sourcing profile scripts before running /etc/X11/Xsession. For example to use a script from the sddm package create a file like /etc/lightdm/lightdm.conf.d/80-session-wrapper-sddm.conf


See Also

Debian-specific information

Upstream specific information

Other information

CategoryBootProcess CategorySoftware CategoryDesktopEnvironment