The X display manager (xdm) is a program that allows for a graphical session to begin on an X server.
xdm is distributed as part of X.Org and is configured by a series of files located in /etc/X11/xdm. These files include:
This file controls inbound requests from remote hosts.
This file is similar to .Xresources, discussed earlier. It holds configuration information for some xdm resources, including the graphical login screen. This file can be edited to modify the appearance of the xdm login screen.
This file associates the X display names (
:1, ...) with either the local X server software or a foreign display, such as an X terminal.
This file contains the script xdm launches after a successful login. It usually looks for .Xsession in the user’s home directory and executes the commands found there. If such a file doesn’t exist, Xsession starts a default window manager (or environment) and applications.
This file is a script started before the graphical login screen. It often includes commands to set colors, display graphics, or run other programs. This script is executed as root.
This file associates xdm configuration resources with the other files in this list. It usually isn’t necessary to make changes in this file unless an expert administrator plans to customize xdm configuration.