XDMSHELL(1)XDMSHELL(1)NAMExdmshell - shell for starting xdm on login
SYNOPSIS
/usr/bin/xdmshell
DESCRIPTION
Xdmshell can be used on systems that are configured to start a console
in text mode by default, to allow users to start the X display manager
by logging in as a special user with the shell set to the xdmshell pro‐
gram.
Many servers set the keyboard to do non-blocking I/O under the assump‐
tion that they are the only programs attempting to read from the key‐
board. Unfortunately, some versions of getty(8) will immediately see a
continuous stream of zero-length reads which they interpret as end-of-
file indicators. Eventually, init(8) will disable logins on that line
until somebody types the following as root:
On some platforms, one alternative is to disable logins on the console
and always run xdm(1) from /etc/inittab.
Another approach is to set up an account whose shell is the xdmshell
program found in the xdm distribution. This program is not installed
by default so that site administrators will examine it to see if it
meets their needs. The xdmshell utility makes sure that it is being
run from the appropriate type of terminal, starts xdm, waits for it to
finish, and then resets the console if necessary. If the xdm resources
file (specified by the DisplayManager*resources entry in the xdm-config
file) contains a binding to the abort-display action similar to the
following
xlogin*login.translations: #override Ctrl<Key>R: abort-dis‐
play()
the console can then by restored by pressing the indicated key (Con‐
trol-R in the above example) in the xdm login window.
The xdmshell program is usually installed setuid to root but executable
only by members of a special group, of which the only member is the
account which has xdmshell as its shell:
% grep xdm /etc/passwd
x::101:51:Account for starting up X:/tmp:/usr/bin/xdmshell
% grep 51 /etc/group
xdmgrp:*:51:
% ls -lg /usr/bin/xdmshell
-rws--x--- 1 root xdmgrp 20338 Nov 1 01:32 /usr/bin/xdmshell
If the xdm resources have not been configured to have a key bound to
the abort-display() action, there will be no way for general users to
login to the console directly. Whether or not this is desirable
depends on the particular site.
SEE ALSOX(7), xdm(1), xinit(1)X Version 11 xdm 1.1.11 XDMSHELL(1)
