Binary package “xdm” in ubuntu intrepid
X display manager
xdm manages a collection of X servers, which may be on the local host or
remote machines. It provides services similar to those provided by init,
getty, and login on character-based terminals: prompting for login name and
password, authenticating the user, and running a session. xdm supports XDMCP
(X Display Manager Control Protocol) and can also be used to run a chooser
process which presents the user with a menu of possible hosts that offer
XDMCP display management.
If the sessreg package is installed, xdm can use the sessreg utility to
register login sessions to the system utmp file; this, however, is not
necessary for xdm to function.
xdm requires the C preprocessor (cpp) to process its configuration files.