LightDM

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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

Installation

USE flags

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

+gnome	Add GNOME support
+gtk	Pull in the gtk+ greeter
+introspection	Add support for GObject based introspection
X	Add support for X11
audit	Enable support for Linux audit subsystem using sys-process/audit
elogind	Enable session tracking via sys-auth/elogind
non-root	Use non-root user by default
systemd	Enable use of systemd-specific libraries and features like socket activation or session tracking
vala	Enable bindings for dev-lang/vala

Data provided by the Gentoo Package Database · Last update: 2025-05-01 10:05 More information about USE flags

Emerge

Install lightdm:

root #emerge --ask x11-misc/lightdm

Configuration

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

• /etc/lightdm/lightdm.conf

GTK+

/etc/lightdm/lightdm-gtk-greeter.conf

KDE

/etc/lightdm/lightdm-kde-greeter.conf

The LightDM KDE greeter also provides a KCM (KDE Control Module), which appears in the System Settings under System Administration → Login 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

[SeatDefaults]
…
greeter-session=lightdm-kde-greeter

RazorQt

The RazorQt greeter currently does not offer any configuration options.

Boot service

OpenRC

Set LightDM as the default display manager:

FILE /etc/conf.d/xdm

DISPLAYMANAGER="lightdm"

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

systemd

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

For example, to lock the current seat:

user $dm-tool lock

Troubleshooting

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.