wdm - WINGs Display Manager
wdm [ options ]
wdm is an X display manager based on the original X11 X Display Manager (xdm). It features numerous functionality improvements, including
the ability to reboot or halt the machine (once the proper password has been supplied) and to select from a list of available X sessions to
start. The look of the login panel is somewhat configurable, too.
Except for -config, all of these options can be specified as resources.
Names the configuration file, which specifies resources to control the behavior of wdm. #configdir#/wdm-config is the default.
Specifies ``false'' as the value for the DisplayManager.daemonMode resource. This suppresses the normal daemon behavior, which is
for wdm to close all file descriptors, disassociate itself from the controlling terminal, and put itself in the background when it
first starts up.
Specifies the numeric value for the DisplayManager.debugLevel resource. A non-zero value causes wdm to print lots of debugging
statements to the terminal; it also disables the DisplayManager.daemonMode resource, forcing wdm to run synchronously. To interpret
these debugging messages, a copy of the source code for wdm is almost a necessity. No attempt has been made to rationalize or stan-
dardize the output.
Specifies the value for the DisplayManager.errorLogFile resource. This file contains errors from wdm as well as anything written to
stderr by the various scripts and programs run during the progress of the session.
Specifies the value for the DisplayManager.syslogFacility resource. This is factility to use with all messages if log is redirected
Specifies ``true'' as the value for the DisplayManager.useSyslog resource. This will force all messages go to syslog with facility
specified by DisplayManager.syslogFacility resource.
Specifies ``false'' as the value for the DisplayManager.useSyslog resource. This will force all messages go to log file specified by
Specifies the value for the DisplayManager*resources resource. This file is loaded using xrdb to specify configuration parameters
for the authentication widget.
Specifies the value for the DisplayManager.servers resource.
Specifies the value for the DisplayManager.requestPort resource. This sets the port-number which wdm will monitor for XDMCP
requests. As XDMCP uses the registered well-known UDP port 177, this resource should not be changed except for debugging. If set to
0 wdm will not listen for XDMCP or Chooser requests.
Specifies the value for the DisplayManager*session resource. This indicates the program to run as the session after the user has
Allows an arbitrary resource to be specified, as in most X Toolkit applications.
At many stages the actions of wdm can be controlled through the use of its configuration file, which is in the X resource format. Some
resources modify the behavior of wdm on all displays, while others modify its behavior on a single display. Where actions relate to a spe-
cific display, the display name is inserted into the resource name between ``DisplayManager'' and the final resource name segment.
For local displays, the resource name and class are as read from the Xservers file.
For remote displays, the resource name is what the network address of the display resolves to. See the removeDomain resource. The name
must match exactly; wdm is not aware of all the network aliases that might reach a given display. If the name resolve fails, the address
is used. The resource class is as sent by the display in the XDMCP Manage request.
Because the resource manager uses colons to separate the name of the resource from its value and dots to separate resource name parts, wdm
substitutes underscores for both dots and colons when generating the resource name. For example, DisplayManager.expo_x_org_0.startup is
the name of the resource which defines the startup shell file for the ``expo.x.org:0'' display.
This resource either specifies a file name full of server entries, one per line (if the value starts with a slash), or a single
server entry. See the section Local Server Specification for the details.
This indicates the UDP port number which wdm uses to listen for incoming XDMCP requests. Unless you need to debug the system, leave
this with its default value of 177.
Error output is normally directed at the system console. To redirect it, set this resource to a file name. A method to send these
messages to syslog should be developed for systems which support it; however, the wide variety of interfaces precludes any system-
independent implementation. This file also contains any output directed to stderr by the Xsetup, Xstartup, Xsession and Xreset
files, so it will contain descriptions of problems in those scripts as well.
If the integer value of this resource is greater than zero, reams of debugging information will be printed. It also disables daemon
mode, which would redirect the information into the bit-bucket, and allows non-root users to run wdm, which would normally not be
Normally, wdm attempts to make itself into a daemon process unassociated with any terminal. This is accomplished by forking and
leaving the parent process to exit, then closing file descriptors and releasing the controlling terminal. In some environments this
is not desired (in particular, when debugging). Setting this resource to ``false'' will disable this feature.
The filename specified will be created to contain an ASCII representation of the process-id of the main wdm process. Xdm also uses
file locking on this file to attempt to eliminate multiple daemons running on the same machine, which would cause quite a bit of
This is the resource which controls whether wdm uses file locking to keep multiple display managers from running amok. On System V,
this uses the lockf library call, while on BSD it uses flock.
This names a directory under which wdm stores authorization files while initializing the session. The default value is #configdir#.
Can be overridden for specific displays by DisplayManager.DISPLAY.authFile.
This boolean controls whether wdm rescans the configuration, servers, access control and authentication keys files after a session
terminates and the files have changed. By default it is ``true.'' You can force wdm to reread these files by sending a SIGHUP to
the main process.
When computing the display name for XDMCP clients, the name resolver will typically create a fully qualified host name for the ter-
minal. As this is sometimes confusing, wdm will remove the domain name portion of the host name if it is the same as the domain
name of the local host when this variable is set. By default the value is ``true.''
XDM-AUTHENTICATION-1 style XDMCP authentication requires that a private key be shared between wdm and the terminal. This resource
specifies the file containing those values. Each entry in the file consists of a display name and the shared key. By default, wdm
does not include support for XDM-AUTHENTICATION-1, as it requires DES which is not generally distributable because of United States
To prevent unauthorized XDMCP service and to allow forwarding of XDMCP IndirectQuery requests, this file contains a database of
hostnames which are either allowed direct access to this machine, or have a list of hosts to which queries should be forwarded to.
The format of this file is described in the section XDMCP Access Control.
A list of additional environment variables, separated by white space, to pass on to the Xsetup, Xstartup, Xsession, and Xreset pro-
A file to checksum to generate the seed of authorization keys. This should be a file that changes frequently. The default is
On systems that support a dynamically-loadable greeter library, the name of the library. The default is /usr/lib/X11/xdm/libXdm-
Greet.so. This not used in Debian.
Number of seconds to wait for display to respond after user has selected a host from the chooser. If the display sends an XDMCP
IndirectQuery within this time, the request is forwarded to the chosen host. Otherwise, it is assumed to be from a new session and
the chooser is offered again. Default is 15.
Use the numeric IP address of the incoming connection on multihomed hosts instead of the host name. This is to avoid trying to con-
nect on the wrong interface which might be down at this time.
This specifies a program which is run (as) root when an an XDMCP BroadcastQuery is received and this host is configured to offer
XDMCP display management. The output of this program may be displayed on a chooser window. If no program is specified, the string
Willing to manage is sent.
This resource specifies the name of the file to be loaded by xrdb as the resource database onto the root window of screen 0 of the
display. The Xsetup program, the Login widget, and chooser will use the resources set in this file. This resource data base is
loaded just before the authentication procedure is started, so it can control the appearance of the login window. See the section
Authentication Widget, which describes the various resources that are appropriate to place in this file. There is no default value
for this resource, but #configdir#/Xresources is the conventional name.
Specifies the program run to offer a host menu for Indirect queries redirected to the special host name CHOOSER.
/usr/X11R6/bin/chooser is the default. See the sections XDMCP Access Control and Chooser.
Specifies the program used to load the resources. By default, wdm uses /usr/X11R6/bin/xrdb.
This specifies the name of the C preprocessor which is used by xrdb.
This specifies a program which is run (as root) before offering the Login window. This may be used to change the appearance of the
screen around the Login window or to put up other windows (e.g., you may want to run xconsole here). By default, no program is run.
The conventional name for a file used here is Xsetup. See the section Setup Program.
This specifies a program which is run (as root) after the authentication process succeeds. By default, no program is run. The con-
ventional name for a file used here is Xstartup. See the section Startup Program.
This specifies the session to be executed (not running as root). By default, /usr/X11R6/bin/xterm is run. The conventional name is
Xsession. See the section Session Program.
This specifies a program which is run (as root) after the session terminates. By default, no program is run. The conventional name
is Xreset. See the section Reset Program.
These numeric resources control the behavior of wdm when attempting to open intransigent servers. openDelay is the length of the
pause (in seconds) between successive attempts, openRepeat is the number of attempts to make, openTimeout is the amount of time to
wait while actually attempting the open (i.e., the maximum time spent in the connect(2) system call) and startAttempts is the number
of times this entire process is done before giving up on the server. After openRepeat attempts have been made, or if openTimeout
seconds elapse in any particular attempt, wdm terminates and restarts the server, attempting to connect again. This process is
repeated startAttempts times, at which point the display is declared dead and disabled. Although this behavior may seem arbitrary,
it has been empirically developed and works quite well on most systems. The default values are 5 for openDelay, 5 for openRepeat,
30 for openTimeout and 4 for startAttempts.
To discover when remote displays disappear, wdm occasionally pings them, using an X connection and XSync calls. pingInterval speci-
fies the time (in minutes) between each ping attempt, pingTimeout specifies the maximum amount of time (in minutes) to wait for the
terminal to respond to the request. If the terminal does not respond, the session is declared dead and terminated. By default,
both are set to 5 minutes. If you frequently use X terminals which can become isolated from the managing host, you may wish to
increase this value. The only worry is that sessions will continue to exist after the terminal has been accidentally disabled. wdm
will not ping local displays. Although it would seem harmless, it is unpleasant when the workstation session is terminated as a
result of the server hanging for NFS service and not responding to the ping.
This boolean resource specifies whether the X server should be terminated when a session terminates (instead of resetting it). This
option can be used when the server tends to grow without bound over time, in order to limit the amount of time the server is run.
The default value is ``false.''
Xdm sets the PATH environment variable for the session to this value. It should be a colon separated list of directories; see sh(1)
for a full description. ``:/bin:/usr/bin:/usr/X11R6/bin:/usr/ucb'' is a common setting. The default value can be specified at
build time in the X system configuration file with DefaultUserPath.
Xdm sets the PATH environment variable for the startup and reset scripts to the value of this resource. The default for this
resource is specified at build time by the DefaultSystemPath entry in the system configuration file;
``/etc:/bin:/usr/bin:/usr/X11R6/bin:/usr/ucb'' is a common choice. Note the absence of ``.'' from this entry. This is a good prac-
tice to follow for root; it avoids many common Trojan Horse system penetration schemes.
Xdm sets the SHELL environment variable for the startup and reset scripts to the value of this resource. It is /bin/sh by default.
If the default session fails to execute, wdm will fall back to this program. This program is executed with no arguments, but exe-
cutes using the same environment variables as the session would have had (see the section Session Program). By default,
/usr/X11R6/bin/xterm is used.
To improve security, wdm grabs the server and keyboard while reading the login name and password. The grabServer resource specifies
if the server should be held for the duration of the name/password reading. When ``false,'' the server is ungrabbed after the key-
board grab succeeds, otherwise the server is grabbed until just before the session begins. The default is ``false.'' The grabTime-
out resource specifies the maximum time wdm will wait for the grab to succeed. The grab may fail if some other client has the
server grabbed, or possibly if the network latencies are very high. This resource has a default value of 3 seconds; you should be
cautious when raising it, as a user can be spoofed by a look-alike window on the display. If the grab fails, wdm kills and restarts
the server (if possible) and the session.
authorize is a boolean resource which controls whether wdm generates and uses authorization for the local server connections. If
authorization is used, authName is a list of authorization mechanisms to use, separated by white space. XDMCP connections dynami-
cally specify which authorization mechanisms are supported, so authName is ignored in this case. When authorize is set for a dis-
play and authorization is not available, the user is informed by having a different message displayed in the login widget. By
default, authorize is ``true.'' authName is ``MIT-MAGIC-COOKIE-1,'' or, if XDM-AUTHORIZATION-1 is available, ``XDM-AUTHORIZA-
This file is used to communicate the authorization data from wdm to the server, using the -auth server command line option. It
should be kept in a directory which is not world-writable as it could easily be removed, disabling the authorization mechanism in
the server. If not specified, a name is generated from DisplayManager.authDir and the name of the display.
If set to ``false,'' disables the use of the unsecureGreeting in the login window. See the section Authentication Widget. The
default is ``true.''
The number of the signal wdm sends to reset the server. See the section Controlling the Server. The default is 1 (SIGHUP).
The number of the signal wdm sends to terminate the server. See the section Controlling the Server. The default is 15 (SIGTERM).
The original implementation of authorization in the sample server reread the authorization file at server reset time, instead of
when checking the initial connection. As wdm generates the authorization information just before connecting to the display, an old
server would not get up-to-date authorization information. This resource causes wdm to send SIGHUP to the server after setting up
the file, causing an additional server reset to occur, during which time the new authorization information will be read. The
default is ``false,'' which will work for all MIT servers.
When wdm is unable to write to the usual user authorization file ($HOME/.Xauthority), it creates a unique file name in this direc-
tory and points the environment variable XAUTHORITY at the created file. It uses /tmp by default.
Specifies the path to wdmLogin(1x)
Is a colon separated list of window managers to use as options in the login panel. Note that if you include the path to the window
manager, it will look ugly. You may set this resource to None if you want only NoChange to appear.
Path to the logo pixmap, several formats are accepted, read wdmLogin(1x) to find out more.
Path to a text file which will be displayed in the help panel, read wdmLogin(1x) to find out more.
a default username which will be used if no username is typed.
the clear text password of the default user above. BE VERY CAREFUL when using this two resources, and don't forget to do: chmod 600
wdm-config ; chown root.root wdm-config
Background specification. Read the BACKGROUND IMAGE SPECIFICATION section to find out about the format. If this is not specified,
then the background is not set.
If true, verify user's identity for reboot/halt/exit.
If true, user must be root to exit.
If true, enable animations consisting of shaking the panel (if an error) and rolling up the panel (when closing it). If false, ani-
mations are disabled.
LANG environment variable will be set to value of this resource before starting wdmLogin.
If you have recent version of XFree with support for transparent cursors you can select cursor theme to use on login panel. XCUR-
SOR_THEME environment variable will be set to value of this resource before starting wdmLogin.
The default location of the wdm configuration file is #configdir#/wdm-config
Here is a reasonable configuration file, which could be named wdm-config:
Note that this file mostly contains references to other files. Note also that some of the resources are specified with ``*'' separating
the components. These resources can be made unique for each different display, by replacing the ``*'' with the display-name, but normally
this is not very useful. See the Resources section for a complete discussion. If the entry is a host name, all comparisons are done using
network addresses, so any name which converts to the correct network address may be used. For patterns, only canonical host names are used
in the comparison, so ensure that you do not attempt to match aliases. Preceding either a host name or a pattern with a `!' character
causes hosts which match that entry to be excluded.
To only respond to Direct queries for a host or pattern, it can be followed by the optional ``NOBROADCAST'' keyword. This can be used to
prevent an wdm server from appearing on menus based on Broadcast queries.
An Indirect entry also contains a host name or pattern, but follows it with a list of host names or macros to which indirect queries should
A macro definition contains a macro name and a list of host names and other macros that the macro expands to. To distinguish macros from
hostnames, macro names start with a `%' character. Macros may be nested.
Indirect entries may also specify to have wdm run chooser to offer a menu of hosts to connect to. See the section Chooser.
When checking access for a particular display host, each entry is scanned in turn and the first matching entry determines the response.
Direct and Broadcast entries are ignored when scanning for an Indirect entry and vice-versa.
Blank lines are ignored, `#' is treated as a comment delimiter causing the rest of that line to be ignored, and `
ewline' causes the new-
line to be ignored, allowing indirect host lists to span multiple lines.
Here is an example Xaccess file:
# Xaccess - XDMCP access control file
# Direct/Broadcast query entries
!xtra.lcs.mit.edu # disallow direct/broadcast service for xtra
bambi.ogi.edu # allow access from this particular display
*.lcs.mit.edu # allow access from any display in LCS
*.deshaw.com NOBROADCAST # allow only direct access
*.gw.com # allow direct and broadcast
# Indirect query entries
%HOSTS expo.lcs.mit.edu xenon.lcs.mit.edu
extract.lcs.mit.edu xenon.lcs.mit.edu #force extract to contact xenon
!xtra.lcs.mit.edu dummy #disallow indirect access
*.lcs.mit.edu %HOSTS #all others get to choose
The Xresources file is loaded onto the display as a resource database using xrdb. As the authentication widget reads this database before
starting up, it usually contains parameters for that widget:
<Key>F1: set-session-argument(failsafe) finish-field()
<Key>Return: set-session-argument() finish-field()
Please note the translations entry; it specifies a few new translations for the widget which allow users to escape from the default session
(and avoid troubles that may occur in it). Note that if #override is not specified, the default translations are removed and replaced by
the new value, not a very useful result as some of the default translations are quite useful (such as ``<Key>: insert-char ()'' which
responds to normal typing).
This file may also contain resources for the setup program and chooser.
The Xsetup file is run after the server is reset, but before the Login window is offered. The file is typically a shell script. It is run
as root, so should be careful about security. This is the place to change the root background or bring up other windows that should appear
on the screen along with the Login widget.
In addition to any specified by DisplayManager.exportList, the following environment variables are passed:
DISPLAY the associated display name
PATH the value of DisplayManager.DISPLAY.systemPath
SHELL the value of DisplayManager.DISPLAY.systemShell
XAUTHORITY may be set to an authority file
Note that since wdm grabs the keyboard, any other windows will not be able to receive keyboard input. They will be able to interact with
the mouse, however; beware of potential security holes here. If DisplayManager.DISPLAY.grabServer is set, Xsetup will not be able to con-
nect to the display at all. Resources for this program can be put into the file named by DisplayManager.DISPLAY.resources.
Here is a sample Xsetup script:
# Xsetup_0 - setup script for one workstation
xcmsdb < /usr/X11R6/lib/monitors/alex.0
xconsole -geometry 480x130-0-0 -notify -verbose -exitOnFail &
BACKGROUND IMAGE SPECIFICATION
There are several possible ways of specifing a background image. The generic format is type:image. type can be any of:
none The backgound is not set.
solid it renders a solid backgroud, and image is a color name
hgradient, vgradient, dgradient
a gradient (either horizontal, vertical or diagonal) will be rendered. image is comma separated of color names, and any number of
colors can be specified.
pixmap a pixmap will be used for the background. image is the full path to an image file (tiff, png, jpeg and xpm allowed) and it will be
scaled to use the full screen.
wdm was written by Gene Czarcinski <firstname.lastname@example.org>. wdm is based on work by Tom Rothamel and xdm, (c) 1988 X Consortium
This man page was written by Marcelo Magallon <email@example.com> and extensively modified by Noah Meyerhans <firstname.lastname@example.org>. Much of
the content was taken from xdm's manual page.
July 2002 wdm(1x)