LightDM

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LightDM is a cross-desktop display manager that aims to be the standard display manager for the X server. Its key features are:

  • A lightweight codebase
  • Standards compliant (PAM, ConsoleKit, etc)
  • A well defined interface between the server and the user interface.
  • Cross-desktop (user interfaces can be written in any toolkit).

More details about LightDM's design can be found here.

Installation

Install lightdm from the official repositories or lightdm-bzrAUR from the AUR.

Greeter

You will also need to install a greeter (a user interface for LightDM). The reference greeter is lightdm-gtk-greeter, which is provided by either lightdm-gtk3-greeter or lightdm-gtk2-greeter. KDE users can install lightdm-kde-greeter, a greeter based on Qt.

Other greeters can be installed from the AUR as well:

You can change the default greeter at compile time by changing the line containing:

--with-greeter-session=lightdm-gtk-greeter

to

--with-greeter-session=lightdm-yourgreeter-greeter

Or, more easily, change the configuration file to state:

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

Enabling LightDM

Make sure that the lightdm daemon is started at boot.

Testing

First, install xorg-server-xephyr from the official repositories.

Then, run LightDM as an X application:

$ lightdm --test-mode --debug

Optional Configuration and Tweaks

Some greeters have their own configuration files. For example, lightdm-gtk3-greeter and lightdm-gtk2-greeter have:

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

and lightdm-kde-greeter has:

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

as well as a section in KDE's System Settings (recommended).

LightDM can be configured by directly modifying its configuration script or by using the lightdm-set-defaults applications that can be found in /usr/lib/lightdm/lightdm/. To see some of the options available, execute:

$ man lightdm-set-defaults

There are, however, a lot more variables to modify in the configuration file than by using the lightdm-set-defaults application.

Changing Background Images/Colors

Users wishing to have a flat color (no image) may simply set the background variable to a hex color.

Example:

background=#000000

If you want to use an image instead, see below.

GTK+ Greeter

Users wishing to customize the wallpaper on the greeter screen need to edit /etc/lightdm/lightdm-gtk-greeter.conf defining the background variable.

Example:

background=/usr/share/pixmaps/black_and_white_photography-wallpaper-1920x1080.jpg

Unity Greeter

Users using the lightdm-unity-greeterAUR must edit the /usr/share/glib-2.0/schemas/com.canonical.unity-greeter.gschema.xml file and then execute:

# glib-compile-schemas /usr/share/glib-2.0/schemas/

According to this page.

Note: It is recommended to place the PNG or JPG file in /usr/share/pixmaps since the LightDM user needs read access to the wallpaper file.

KDE Greeter

Go to System Settings > Login Screen (LightDM) and change the background image for your theme.

Changing the Icon

Users wishing to customize the icon on the greeter screen need to edit /etc/lightdm/lightdm-gtk-greeter.conf defining the logo variable.

Example:

logo=/usr/share/icons/hicolor/64x64/devices/archlinux-icon-crystal-64.svg

Sources of Arch-centric 64x64 Icons

The archlinux-artwork package from the official repositories contains some nice examples that install to /usr/share/archlinux/icons and that can be copied to /usr/share/icons/hicolor/64x64/devices as follows:

# find /usr/share/archlinux/icons -name "*64*" -exec cp {} /usr/share/icons/hicolor/64x64/devices \;

After copying, the archlinux-artwork package can be removed.

Enabling Autologin

Edit the LightDM configuration file and change these lines to:

/etc/lightdm/lightdm.conf
autologin-user=<your_username>
autologin-user-timeout=0

or execute:

# /usr/lib/lightdm/lightdm/lightdm-set-defaults --autologin=USERNAME

LightDM goes through PAM even when autologin is enabled. You must be part of the autologin group to be able to login without entering your password:

# groupadd autologin
# gpasswd -a username autologin
Note: GNOME users, and by extension any gnome-keyring user will have to set up a blank password to their keyring for it to be unlocked automatically.

NumLock ON

Install the numlockx package and the edit /etc/lightdm/lightdm.conf adding the following line:

greeter-setup-script=/usr/bin/numlockx on

User switching under xfce4

With the release of Xfce4 4.10, user switching is supported natively. To use it with LightDM, users need only to create a symlink:

# ln -s /usr/lib/lightdm/lightdm/gdmflexiserver /usr/bin/gdmflexiserver

Alternatively, see the XScreenSaver#Lightdm article.

See Also