XDM

Summary
XDM is the X Display Manager.
Related
Display Manager

From XDM manual page:

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.

1 Installation

Install xorg-xdm, available in the Official Repositories.

Make the ~/.xsession file executable.

$ chmod 744 .xsession

2 Background wallpaper

Here are some tips to make XDM look nicer:

• Install the Quick Image Viewer:

# pacman -S qiv

• Make a directory to store background images. (e.g. /root/backgrounds or /usr/local/share/backgrounds)

• Place your images in the directory. If you do not have any try [1] for starters.

• Edit /etc/X11/xdm/Xsetup_0. Change the xconsole command to:

 /usr/bin/qiv -zr /root/backgrounds/*

• Edit /etc/X11/xdm/Xresources. Add/replace the following defines:

 xlogingreetFont:  -liberation-mono-bold-o-normal--20------iso8859-1
 xloginfont:       -liberation-mono-medium-r-normal--14------iso8859-1
 xloginpromptFont: -liberation-mono-bold-r-normal--14------iso8859-1
 xloginfailFont:   -liberation-mono-bold-r-normal--14------iso8859-1
 xlogin*frameWidth: 1
 xlogin*innerFramesWidth: 1
 xlogin*logoPadding: 0
 xlogin*geometry:    300x175-0-0

Comment out the logo defines:

 #xlogin*logoFileName: /usr/X11R6/lib/X11/xdm/pixmaps/xorg.xpm
 #xlogin*logoFileName: /usr/X11R6/lib/X11/xdm/pixmaps/xorg-bw.xpm

For the exact meaning of the definitions, see the man page of xdm.

• Update /etc/pacman.conf so the changes do not get erased:

 ~NoUpgrade   = etc/X11/xdm/Xsetup_0 etc/X11/xdm/Xresources

The changes will now give you a random wallpaper image and move the login prompt to the bottom-right edge of the screen.

3 Multiple X sessions & Login in the window

With the Xdmcp enable, you can easily run multiple X sessions simultaneously on the same machine.

# X -query ip_xdmcp_server :2 

This will launch the second session, in window you need xorg-server-xephyr

# Xephyr -query this_machine_ip :2 

4 Troubleshooting

4.1 XDM loops back to itself after login

The current version of the xorg-xdm package, available in the Official Repositories is patched to register sessions with ConsoleKit by default. If ConsoleKit is not running, XDM will fail to succesfully launch an X session. D-Bus can be used invoke ConsoleKit when called upon by XDM.

Make sure that the dbus package, available in the Official Repositories is installed and then make sure dbus is included in the DAEMONS array in /etc/rc.conf.

Also, make sure that you are actually starting your window manager, for example with the command xmonad in ~/.xsession.

4.2 XDM does not update login records

The vanilla config of XDM calls /etc/X11/xdm/GiveConsolve for the startup of display :0, whereas otherwise it calls /etc/X11/xdm/Xstartup. Since only the latter contains a call to /usr/bin/sessreg, the login record /var/run/utmp is not updated for a login on display :0. As a consequence, the output of who does not necessarily list the user after login through XDM. This was already discussed in the bug report FS#26395.

As a simple fix, append the following line to /etc/X11/xdm/GiveConsole:

exec /usr/bin/sessreg -a -w /var/log/wtmp -u /var/run/utmp -x /etc/X11/xdm/Xservers -l $DISPLAY -h "" $USER

This change also enables the getuser function presented in Acpid to work.

5 Acknowledgement

This wiki article is based on ArchWiki. We may have removed non-FSDG bits from it.