XDM

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From xdm(8) § DESCRIPTION:

Xdm manages a collection of X displays, which may be on the local host or remote servers. The design of xdm was guided by the needs of X terminals as well as The Open Group standard XDMCP, the X Display Manager Control Protocol. Xdm provides services similar to those provided by init, getty and login on character terminals: prompting for login name and password, authenticating the user, and running a "session."

XDM provides a simple and straightforward graphical login prompt.

Installation

Install the xorg-xdm package. Then enable xdm.service.

If you would like to use an Arch Linux theme for XDM, you can optionally install the xdm-archlinux package. If installing the latter package, then do not enable xdm.service, but instead enable xdm-archlinux.service.

Configuration

Defining the session

Unlike many more modern display managers such as GDM or LightDM, XDM does not source available sessions from .desktop files located in the /usr/share/xsessions directory. As such, XDM does not have a 'session menu.' Instead, XDM will execute the .xsession file in the home directory.

For example, to start Xfce upon login, the ~/.xsession file should look like this: 

startxfce4

Ensure that the .xsession file in your home directory is executable.

Theming

For the exact meanings of the options discussed below, see xdm(8). The configuration file is located in /etc/X11/xdm/Xresources, notice that if you installed xdm-archlinux the configuration file will instead be located in /etc/X11/xdm/archlinux/Xresources.

Background wallpaper

Install qiv.

Create a directory to put wallpapers in, e.g /usr/local/share/backgrounds and then place them inside it.

Edit /etc/X11/xdm/Xsetup_0. Change the xconsole command to /usr/bin/qiv -zr /usr/local/share/backgrounds/*

Font

  • Edit /etc/X11/xdm/Xresources. Add/replace the following defines:
xlogin*greetFont:  -adobe-helvetica-bold-o-normal--20------iso8859-1
xlogin*font:       -adobe-helvetica-medium-r-normal--14------iso8859-1
xlogin*promptFont: -adobe-helvetica-bold-r-normal--14------iso8859-1
xlogin*failFont:   -adobe-helvetica-bold-r-normal--14------iso8859-1

Login dialog positioning

This configuration will move the login dialog to the bottom right of the screen. 

xlogin*frameWidth: 1
xlogin*innerFramesWidth: 1
xlogin*logoPadding: 0
xlogin*geometry:    300x175-0-0

Comment out the logo defines: 

#xlogin*logoFileName: /usr/share/xdm/pixmaps/xorg.xpm
#xlogin*logoFileName: /usr/share/xdm/pixmaps/xorg-bw.xpm

Multiple X sessions & Login in the window

With the XDMCP enabled, you can easily connect to local or remote XDM instance and run multiple X sessions simultaneously on the same machine: 

# X -query xdmcp-server-ip :2

This command will launch the second session in window using Xephyr: 

$ Xephyr -query xdmcp-server-ip :2

Passwordless login

In order to enable passwordless login for XDM, add the line below to /etc/X11/xdm/Xresources: 

xlogin*allowNullPasswd: true