xdm.options - configuration options for the X display manager
/etc/X11/xdm/xdm.options contains a set of flags that determine some of
the behavior of the X display manager xdm(1x). Most of xdm’s behavior
is customized through other files; consult the xdm manual page if this
manual page does not describe the behavior you want to alter.
/etc/X11/xdm/xdm.options may contain comments, which begin with a hash
mark (‘#’) and end at the next newline, just like comments in shell
scripts. The rest of the file consists of options which are expressed
as words separated by hyphens, with only one option per line. Options
are enabled by simply placing them in the file; they are disabled by
prefixing the option name with ‘no-’.
Available options are:
Normally, if the nologin(5) file exists, its contents will be
displayed using xmessage(1x) (if xmessage is available), and the
user will be returned to the xdm login screen after xmessage is
dismissed instead of starting the X session. If this option is
enabled, xdm starts a session as usual (after xmessage is
dismissed, if xmessage is available and the nologin file
exists). This behavior is disabled by default: nologin is
heeded, not ignored.
Enable this option with caution on ‘production’ machines; it
causes the daemon to be stopped and restarted on upgrade, even
if the process has children (which means it is managing X
sessions). Typically when a package that contains a daemon is
being installed or upgraded, its maintainer scripts stop a
running daemon process before installing the new binary, and
restart it after the new binary is installed. Stopping xdm
causes immediate termination of any sessions it manages; in some
situations this could be an unwelcome surprise (for instance,
for remote xdm users who had no idea the administrator was
performing system maintenance). On the other hand, for machines
that stay up for long periods of time, leaving the old daemon
running can be a bad idea if the new version has, for instance,
a fix for a security vulnerability (overwriting xdm’s executable
on the file system has no effect on the copy of xdm in memory).
The xdm package’s pre-removal script checks to see if the xdm
process has any children; if it does, it is possible that
someone’s session would be killed by stopping xdm, so a warning
is issued and an opportunity to abort the upgrade of xdm is
provided. Furthermore, restarting xdm on upgrade can be
surprising, because a locally-managed X server can change the
active VT even while other packages are continuing to upgrade.
If, by intent or accident, the X server does not honor the key
sequence to switch VTs back to a virtual console, this can be
undesirable. This behavior is disabled by default: xdm will be
not be stopped or started during an upgrade of its package; the
administrator will have to do so by hand (with invoke-rc.d xdm
restart or by rebooting the system) before the newly installed
xdm binary is used.
Enable this option with caution; it causes the xdm daemon to be
started immediately after the package is installed. See the
above entry regarding restart-on-upgrade for other caveats
regarding the consequences of starting the xdm daemon during
package management. This behavior is disabled by default: xdm
will not be started when it is installed. Changing this setting
can affect future installs if the package is removed, but not
purged (which removes ‘conffiles’, including xdm.options).
This option causes the /etc/X11/xdm/Xreset script to call the
sessreg(1x) program to register X sessions managed by xdm in the
utmp(5) and wtmp(5) files. If it is disabled, the utmp and wtmp
files will have no record of xdm sessions. This behavior is
enabled by default; sessreg will be used.
Users of older versions of the Debian system should note that the
‘run-xconsole’ option has been removed. The shell script named
/etc/X11/xdm/Xreset can be edited to disable or modify the running of
xconsole on the xdm greeter screen; see xdm(1x) for more information.
Stephen Early, Mark Eichin, and Branden Robinson customized xdm’s
startup and reset scripts and package maintainer scripts to implement
the functionality described above. This manual page was written by
sessreg(1x), xmessage(1x), xdm(1x), nologin(5), utmp(5), wtmp(5)