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LightDM is a cross-desktop display manager whose aim is to be the standard display manager for the X server.

The key features (as listed by upstream) include:

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


USE flags

USE flags for x11-misc/lightdm A lightweight display manager

gnome Add GNOME support global
gtk Pull in the gtk+ greeter local
introspection Use dev-libs/gobject-introspection for introspection local
kde Pull in the kde greeter local
qt4 Add support for the Qt GUI/Application Toolkit version 4.x global
qt5 Add support for the Qt 5 application and UI framework global


Install lightdm:

root #emerge --ask x11-misc/lightdm


The (global) configuration file for LightDM can be found at:

  • /etc/lightdm/lightdm.conf





The LightDM KDE greeter also provides a KCM (KDE Control Module), which appears in the System Settings under System AdministrationLogin Screen (LightDM).

Due to LightDM currently assuming GTK+ greeter as the default, if the KDE greeter is requested, it needs to be specified in the /etc/lightdm/lightdm.conf file:

FILE /etc/lightdm/lightdm.conf



The RazorQt greeter currently does not offer any configuration options.

Boot service


Set LightDM as the default display manager:

FILE /etc/conf.d/xdm

To start LightDM on boot, add dbus and xdm to the default runlevel:

root #rc-update add dbus default
root #rc-update add xdm default

To start LightDM now:

root #/etc/init.d/dbus start
root #/etc/init.d/xdm start


To start LightDM on boot:

root #systemctl enable lightdm

To start LightDM now:

root #systemctl start lightdm

Command-line tool

LightDM includes a command-line tool, dm-tool, which can be used to switch user sessions, lock the current seat, etc. To see a list of available commands, use the --help option:

user $dm-tool --help
  dm-tool [OPTION...] COMMAND [ARGS...] - Display Manager tool

  -h, --help        Show help options
  -v, --version     Show release version
  --session-bus     Use session D-Bus

  switch-to-greeter                                    Switch to the greeter
  switch-to-user USERNAME [SESSION]                    Switch to a user session
  switch-to-guest [SESSION]                            Switch to a guest session
  lock                                                 Lock the current seat
  list-seats                                           List the active seats
  add-nested-seat [--fullscreen|--screen DIMENSIONS]   Start a nested display
  add-local-x-seat DISPLAY_NUMBER                      Add a local X seat
  add-seat TYPE [NAME=VALUE...] 

For example, to lock the current seat:

user $dm-tool lock


Cursor themes not working

As of March 28, 2015, the stable versions of lightdm (lightdm-1.10.3) and lightdm-gtk-greeter (lightdm-gtk-greeter-1.7.0) have a bug that affects some DEs such as XFCE with setting the mouse cursor. Applications will apply the new mouse theme, but the root window where the window manager draws on does not. To get around this, simply unmask the latest versions (lightdm-1.13.2 and lightdm-gtk-greeter-2.0.0 at the time of writing) and the cursors will be set correctly.

More information can be found in Ubuntu's bug #1024482.