This
page describes the various configuration files used by the Xdm process.
Xdm Authorize
The authorize resource controls the user-based access control
(different from host-based access control governed by xhost).
The
following resources set access control on for the local display and then
using the unqualified authorize afterward to set host-based access
control for other displays.
...
DisplayManager._0.authorize: true
DisplayManager*authorize: false
...
Xresources File
This file contains resources used by Xdm, typically for its login
banner. If you want to change these resources, for instance by adding
your personalized greeting, you do it by modifying entries in this file.
Look in this file to see the resource names and settings.
Xservers File
The Xservers file contains a list of displays which Xdm must
manage. These are typically displays which do not have XDMCP and thus
cannot select to have Xdm manage them. Normally the ViewStation selects
whether Xdm manages its display or not, based on the user's selection in
the XDMCP menu in Setup Mode.
This file is usually empty except for a single entry for the
host computer's local display: :0 Local local
/usr/bin/X11/X :0
The Xservers file was the way Xdm managed network devices
under X11R3. With X11R4 and R5, individual devices send an Xdm request.
Xsetup File
The Xsetup file is a new file with X11R5. In most cases, it is
empty. It allows the user to specify any startup commands that should
be run BEFORE the Xdm banner is up and the user logs in. This would
typically be something like xmodmap that would put special keyboard
modifications in place, such as foreign-language mappings, that the
user would need to type in his name and password.
The ViewStation has a corresponding file, the server-reset
file, that allows this kind of configuration, but run on the
ViewStation for its own configuration. ViewStation
Server Reset File.
The ViewStation also has a local xmodmap
client which can be used for this purpose.
ViewStation Xmodmap client.
Xstartup
File
The Xstartup file contains startup commands that should be executed
AFTER the user has logged in and is verified. This file is typically
empty.
Xreset File
The Xreset file contains commands that should be executed after
the user's login has been verified.
xdm-errors File
The xdm-errors file contains error messages relative to Xdm
operation. If you have problems with Xdm, look in this file.
If you have more extensive Xdm problems, restart Xdm with the
-debug argument set (with a fairly high value, say 30). This will give
extensive error reporting for the Xdm process.
xdm-pid
The xdm-pid file stores the process ID for the parent Xdm process.
This is sometimes an important value, since each Xdm connection spawns a
daughter process and it is difficult to determine which is the parent
process.
There is a resource in the Xresource file which permits
changing this file's name.
Xsession file
The Xsession file (as distinct from the .xsession file) is the
system's default startup script. If there is no user's .xsession file,
this .Xsession file will be used.
Xsession file details are on another page.
In the standard MIT release, this file starts an xterm and the
twm window manager. Of course, your system administrator can modify this
script.
Xdm Versions
There are a number of different versions of Xdm. These are
substantially different depending on their chronology, whether X11R3,
R4, or R5. There are also some differences in vendor releases, though
these differences are generally minor.
If you have problems with your Xdm process, it may be helpful
to look at its version and operation. Look at the Xdm man pages on your
system.
In summary: X11R3 selected hosts to manage by looking at the
Xservers file. This management was set by the system administrator and
had no user selectivity.
X11R4 changed the functionality to permit the user's selection
of Xdm management and the method of making the connection. This was
called XDMCP.
X11R5 improved Xdm control of the management process and added
an Xdm "Chooser" client to aid in selecting an Xdm host.
Xdm Chooser
Xdm, with version X11R5, has a
Chooser client. This is a selection box that lists the Xdm hosts that
are available, generally from an Indirect or Broadcast Xdm access
selection.
ViewStation's Chooser Client
The ViewStation has a local Chooser client. The ViewStation's
Chooser works the same way as the host-based chooser, but it has two
important differences. The ViewStation's chooser works with both X11R4
and X11R5 Xdm processes and it allows the user to enter an Xdm host
into its selection box. These are often very convenient features.
You can start the ViewStation's Chooser client from the XDMCP
menu in Setup Mode. Its operation is described fully in ViewStation Xdm Chooser Client.
The ViewStation's "hosts
file" access option on the XDMCP Options Menu also offers convenient
control of the Xdm process by letting the user select a variety of Xdm
connections, hosts, and timing. ViewStation Xdm
Hosts File.
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