# Display manager

Related articles

- Desktop environment
- Window manager
- Start X at login

A display manager, or login manager, is typically a graphical user interface that is displayed at the end of the boot process in place of the default shell. There are various implementations of display managers, just as there are various types of window managers and desktop environments. There is usually a certain amount of customization and themeability available with each one.

## List of display managers

### Console

- CDM — Ultra-minimalistic, yet full-featured login manager written in Bash.

  https://github.com/ghost1227/cdm || cdm-gitAUR

- Console TDM — Extension for xinit written in pure Bash.

  http://code.google.com/p/t-display-manager/ || console-tdmAUR

- nodm — Minimalistic display manager for automatic logins.

  http://enricozini.org/sw/nodm/ || nodmAUR

### Graphical

- Entrance — An EFL based display manager, highly experimental.

  http://enlightenment.org/ || entrance-gitAUR

- GDM — GNOME display manager.

  http://projects.gnome.org/gdm/ || gdm

- KDM — KDE display manager.

  http://www.kde.org/ || kdebase-workspace

- LightDM — Cross-desktop display manager, can use various front-ends written in any toolkit.

  http://www.freedesktop.org/wiki/Software/LightDM || lightdm

- LXDM — LXDE display manager. Can be used independent of the LXDE desktop environment.

  http://sourceforge.net/projects/lxdm/ || lxdm

- MDM — MDM display manager, used in Linux Mint, a fork of GDM 2.

  https://github.com/linuxmint/mdm || mdm-display-managerAUR

- Qingy — Ultralight and very configurable graphical login independent on X Windows (uses DirectFB).

  http://qingy.sourceforge.net/ || qingyAUR

- SDDM — QML-based display manager and successor to KDE4's kdm; useful with Plasma.

  https://github.com/sddm/sddm || sddm

- SLiM — Lightweight and elegant graphical login solution.

  http://sourceforge.net/projects/slim.berlios/ || slim

- XDM — X display manager with support for XDMCP, host chooser.

  http://www.x.org/archive/X11R7.5/doc/man/man1/xdm.1.html || xorg-xdm

## Loading the display manager

To enable graphical login, enable the appropriate systemd service. For example, for KDM, enable `kdm.service`.

This should work out of the box. If not, you might have a default.target set manually or from an older install:

    $ ls -l /etc/systemd/system/default.target

    [...] /etc/systemd/system/default.target -> /usr/lib/systemd/system/graphical.target

Simply delete the symlink and systemd will use its stock default.target (i.e. graphical.target).

    # rm /etc/systemd/system/default.target

After enabling KDM a symlink display-manager.service should be set in `/etc/systemd/system/`

    $ ls -l /etc/systemd/system/display-manager.service

    [...] /etc/systemd/system/display-manager.service -> /usr/lib/systemd/system/kdm.service

### Using systemd-logind

In order to check the status of your user session, you can use `loginctl`. All polkit actions like suspending the system or mounting external drives will work out of the box.

    $ loginctl show-session $XDG_SESSION_ID

## Tips and tricks

### Session list

Many display managers read available sessions from `/usr/share/xsessions/` directory. It contains standard desktop entry files for each DM/WM.

To add/remove entries to your display manager's session list; create/remove the .desktop files in `/usr/share/xsessions/` as desired. A typical .desktop file will look something like:

    [Desktop Entry]
    Encoding=UTF-8
    Name=Openbox
    Comment=Log in using the Openbox window manager (without a session manager)
    Exec=/usr/bin/openbox-session
    TryExec=/usr/bin/openbox-session
    Icon=openbox.png
    Type=XSession

### Starting applications without a window manager

You can also launch an application without any decoration, desktop, or window management. For example to launch google-chromeAUR create a `web-browser.desktop` file in `/usr/share/xsessions/` like this:

    [Desktop Entry]
    Encoding=UTF-8
    Name=Web Browser
    Comment=Use a web browser as your session
    Exec=/usr/bin/google-chrome --auto-launch-at-startup
    TryExec=/usr/bin/google-chrome --auto-launch-at-startup
    Icon=google-chrome

In this case, once you login, the application set with `Exec` will be launched immediately. When you close the application, you will be taken back to the login manager (same as logging out of a normal DE/WM).

It is important to remember that most graphical applications are not intended to be launched this way and you might have manual tweaking to do or limitations to live with (there is no window manager, so do not expect to be able to move or resize any windows, including dialogs; nonetheless, you might be able to set the window geometry in the application's configuration files).

See also xinitrc#Starting applications without a window manager.

### Autostarting

Most of display managers sources `/etc/xprofile`, `~/.xprofile` and `/etc/X11/xinit/xinitrc.d/`. For more details, see xprofile.

### Set the language

For display manager's that use AccountsService the display manager locale can be set by editing `/var/lib/AccountsService/users/$USER`:

    [User]
    Language=your_locale

where your_locale is a value such as `en_GB.UTF-8`.

Restart your display manager for the changes to take effect.

## Known issues

### Incompatibility with systemd

Affected DMs: Entrance, MDM

Some display managers are not fully compatible with systemd, because they reuse the PAM session process. It causes various problems on second login, e.g.:

- NetworkManager applet does not work,
- PulseAudio volume cannot be adjusted,
- login failed into GNOME with another user.

Category:

- Display managers