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XDM(1)			    General Commands Manual			XDM(1)

NAME
       xdm - X Display Manager with support for	XDMCP, host chooser

SYNOPSIS
       xdm [ -config configuration_file	] [ -nodaemon ]	[ -debug debug_level ]
       [ -error	error_log_file	]  [  -resources  resource_file	 ]  [  -server
       server_entry ] [	-session session_program ]

DESCRIPTION
       Xdm  manages a collection of X displays,	which may be on	the local host
       or remote servers.  The design of xdm was guided	by the needs of	X ter-
       minals  as well as The Open Group standard XDMCP, the X Display Manager
       Control Protocol.  Xdm provides services	similar	to those  provided  by
       init,  getty and	login on character terminals: prompting	for login name
       and password, authenticating the	user, and running a ``session.''

       A ``session'' is	defined	by the lifetime	of a  particular  process;  in
       the  traditional	character-based	terminal world,	it is the user's login
       shell.  In the xdm context, it is an arbitrary session  manager.	  This
       is  because  in	a  windowing environment, a user's login shell process
       does not	necessarily have any terminal-like  interface  with  which  to
       connect.	  When	a real session manager is not available, a window man-
       ager or terminal	emulator is typically used as the ``session manager,''
       meaning that termination	of this	process	terminates the user's session.

       When  the  session  is terminated, xdm resets the X server and (option-
       ally) restarts the whole	process.

       When xdm	receives an Indirect query via XDMCP, it  can  run  a  chooser
       process to perform an XDMCP BroadcastQuery (or an XDMCP Query to	speci-
       fied hosts) on behalf of	the display and	offer a	menu of	possible hosts
       that  offer  XDMCP  display  management.	 This feature is useful	with X
       terminals that do not offer a host menu themselves.

       Xdm can be configured to	ignore BroadcastQuery messages	from  selected
       hosts.	This is	useful when you	don't want the host to appear in menus
       produced	by chooser or X	terminals themselves.

       Because xdm provides the	first interface	that users will	see, it	is de-
       signed to be simple to use and easy to customize	to the needs of	a par-
       ticular site.  Xdm has many options, most of which have reasonable  de-
       faults.	 Browse	 through  the various sections of this manual, picking
       and choosing the	things you want	to change.  Pay	 particular  attention
       to  the	Session	Program	section, which will describe how to set	up the
       style of	session	desired.

OVERVIEW
       xdm is highly configurable, and most of its behavior can	be  controlled
       by  resource  files  and	shell scripts.	The names of these files them-
       selves are resources read from the file xdm-config or the file named by
       the -config option.

       xdm  offers  display  management	 two  different	ways.  It can manage X
       servers running on the local machine and	specified in Xservers, and  it
       can  manage  remote  X servers (typically X terminals) using XDMCP (the
       XDM Control Protocol) as	specified in the Xaccess file.

       The resources of	the X clients run by xdm outside the  user's  session,
       including  xdm's	own login window, can be affected by setting resources
       in the Xresources file.

       For X terminals that do not offer a menu	of hosts to get	 display  man-
       agement from, xdm can collect willing hosts and run the chooser program
       to offer	the user a menu.  For X	displays attached to a host, this step
       is typically not	used, as the local host	does the display management.

       After  resetting	 the X server, xdm runs	the Xsetup script to assist in
       setting up the screen the user sees along with the xlogin widget.

       The xlogin widget, which	xdm presents, offers the  familiar  login  and
       password	prompts.

       After the user logs in, xdm runs	the Xstartup script as root.

       Then  xdm  runs	the  Xsession script as	the user.  This	system session
       file may	do some	additional startup and typically  runs	the  .xsession
       script  in  the user's home directory.  When the	Xsession script	exits,
       the session is over.

       At the end of the session, the Xreset script is run to clean up,	the  X
       server is reset,	and the	cycle starts over.

       The  file   /var/log/xdm.log  will  contain error messages from xdm and
       anything	output to stderr by  Xsetup,  Xstartup,	 Xsession  or  Xreset.
       When  you  have	trouble	getting	xdm working, check this	file to	see if
       xdm has any clues to the	trouble.

OPTIONS
       All of these options, except -config itself, specify  values  that  can
       also be specified in the	configuration file as resources.

       -config configuration_file
	      Names  the configuration file, which specifies resources to con-
	      trol the behavior	 of  xdm.   /usr/local/share/examples/xdm/xdm-
	      config is	the default.  See the section Configuration File.

       -nodaemon
	      Specifies	 ``false'' as the value	for the	DisplayManager.daemon-
	      Mode resource.  This  suppresses	the  normal  daemon  behavior,
	      which is for xdm to close	all file descriptors, disassociate it-
	      self from	the controlling	terminal, and put itself in the	 back-
	      ground when it first starts up.

       -debug debug_level
	      Specifies	 the  numeric  value for the DisplayManager.debugLevel
	      resource.	 A non-zero value causes xdm to	print lots  of	debug-
	      ging  statements	to the terminal; it also disables the Display-
	      Manager.daemonMode resource, forcing xdm to  run	synchronously.
	      To interpret these debugging messages, a copy of the source code
	      for xdm is almost	a necessity.  No attempt has been made to  ra-
	      tionalize	or standardize the output.

       -error error_log_file
	      Specifies	 the  value  for  the  DisplayManager.errorLogFile re-
	      source.  This file contains errors from xdm as well as  anything
	      written to stderr	by the various scripts and programs run	during
	      the progress of the session.

       -resources resource_file
	      Specifies	the value for the  DisplayManager*resources  resource.
	      This  file  is loaded using xrdb(1) to specify configuration pa-
	      rameters for the authentication widget.

       -server server_entry
	      Specifies	the value  for	the  DisplayManager.servers  resource.
	      See  the section Local Server Specification for a	description of
	      this resource.

       -udpPort	port_number
	      Specifies	the value for the DisplayManager.requestPort resource.
	      This  sets  the port-number which	xdm will monitor for XDMCP re-
	      quests.  As XDMCP	uses the registered well-known UDP  port  177,
	      this resource should not be changed except for debugging.	If set
	      to 0 xdm will not	listen for XDMCP or Chooser requests.

       -session	session_program
	      Specifies	the value  for	the  DisplayManager*session  resource.
	      This  indicates the program to run as the	session	after the user
	      has logged in.

       -xrm resource_specification
	      Allows an	arbitrary resource to be specified, as in most X Tool-
	      kit applications.

RESOURCES
       At  many	stages the actions of xdm can be controlled through the	use of
       its configuration file, which is	in the X resource  format.   Some  re-
       sources modify the behavior of xdm on all displays, while others	modify
       its behavior on a single	display.  Where	actions	relate to  a  specific
       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;	xdm 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 re-
       quest.

       Because the resource manager uses colons	to separate the	 name  of  the
       resource	 from  its value and dots to separate resource name parts, xdm
       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.

       DisplayManager.servers
	      This  resource  either  specifies	a file name full of server en-
	      tries, one per line (if the value	starts with  a	slash),	 or  a
	      single server entry.  See	the section Local Server Specification
	      for the details.

       DisplayManager.requestPort
	      This indicates the UDP port number which xdm uses	to listen  for
	      incoming	XDMCP  requests.  Unless you need to debug the system,
	      leave this with its default value	of 177.

       DisplayManager.errorLogFile
	      Error output is normally directed	at the system console.	To re-
	      direct  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.

       DisplayManager.debugLevel
	      If  the  integer	value  of  this	resource is greater than zero,
	      reams of debugging information will be printed.	It  also  dis-
	      ables daemon mode, which would redirect the information into the
	      bit-bucket, and allows non-root users to run  xdm,  which	 would
	      normally not be useful.

       DisplayManager.daemonMode
	      Normally,	 xdm  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 de-
	      scriptors	and releasing the controlling terminal.	 In some envi-
	      ronments	this  is  not desired (in particular, when debugging).
	      Setting this resource to ``false'' will disable this feature.

       DisplayManager.pidFile
	      The filename specified will be created to	contain	an ASCII  rep-
	      resentation of the process-id of the main	xdm 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 havoc.

       DisplayManager.lockPidFile
	      This is the resource which controls whether xdm uses file	 lock-
	      ing  to  keep  multiple  display managers	from running amok.  On
	      System V,	this uses the lockf library call, while	on BSD it uses
	      flock.

       DisplayManager.authDir
	      This  names  a  directory	 under	which xdm stores authorization
	      files while initializing the  session.   The  default  value  is
	      /usr/local/share/examples/xdm.   Can  be overridden for specific
	      displays by DisplayManager.DISPLAY.authFile.

       DisplayManager.autoRescan
	      This boolean controls whether  xdm  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	xdm to reread these files by sending a
	      SIGHUP to	the main process.

       DisplayManager.removeDomainname
	      When computing the display name for XDMCP	clients, the name  re-
	      solver will typically create a fully qualified host name for the
	      terminal.	 As this is sometimes confusing, xdm 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 de-
	      fault the	value is ``true.''

       DisplayManager.keyFile
	      XDM-AUTHENTICATION-1  style XDMCP	authentication requires	that a
	      private key be shared between xdm	and the	 terminal.   This  re-
	      source  specifies	 the file containing those values.  Each entry
	      in the file consists of a	display	name and the shared  key.   By
	      default,	xdm does not include support for XDM-AUTHENTICATION-1,
	      as it requires DES which is not generally	distributable  because
	      of United	States export restrictions.

       DisplayManager.accessFile
	      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 ma-
	      chine, or	have a list of hosts to	which queries should  be  for-
	      warded  to.  The format of this file is described	in the section
	      XDMCP Access Control.

       DisplayManager.exportList
	      A	list of	additional environment variables, separated  by	 white
	      space,  to pass on to the	Xsetup,	Xstartup, Xsession, and	Xreset
	      programs.

       DisplayManager.randomFile
	      A	file to	checksum to generate the seed of  authorization	 keys.
	      This  should  be a file that changes frequently.	The default is
	      /dev/mem.

       DisplayManager.randomDevice
	      A	file to	read 8 bytes from to generate the seed	of  authoriza-
	      tion keys.  The default is  "/dev/urandom" . If this file	cannot
	      be read, or if a read blocks for more than 5 seconds, xdm	 falls
	      back  to using a checksum	of DisplayManager.randomFile to	gener-
	      ate the seed.

       DisplayManager.greeterLib
	      On systems that support a	dynamically-loadable greeter  library,
	      the name of the library.	The default is
	       /usr/local/share/examples/xdm/libXdmGreet.so.

       DisplayManager.choiceTimeout
	      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.

       DisplayManager.sourceAddress
	      Use  the numeric IP address of the incoming connection on	multi-
	      homed hosts instead of the host name. This is to avoid trying to
	      connect on the wrong interface which might be down at this time.

       DisplayManager.willing
	      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 dis-
	      played on	a chooser window.  If no  program  is  specified,  the
	      string Willing to	manage is sent.

       DisplayManager.DISPLAY.resources
	      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 vari-
	      ous resources that are appropriate to place in this file.	 There
	      is no default value for this resource, but
	       /usr/local/share/examples/xdm/Xresources	 is  the  conventional
	      name.

       DisplayManager.DISPLAY.chooser
	      Specifies	the program run	to offer  a  host  menu	 for  Indirect
	      queries redirected to the	special	host name CHOOSER.
	       /usr/local/lib/X11/xdm/chooser	is  the	default.  See the sec-
	      tions XDMCP Access Control and Chooser.

       DisplayManager.DISPLAY.xrdb
	      Specifies	the program used to load the resources.	  By  default,
	      xdm uses	/usr/local/bin/xrdb.

       DisplayManager.DISPLAY.cpp
	      This  specifies  the name	of the C preprocessor which is used by
	      xrdb.

       DisplayManager.DISPLAY.setup
	      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 pro-
	      gram is run.  The	conventional name for  a  file	used  here  is
	      Xsetup.  See the section Setup Program.

       DisplayManager.DISPLAY.startup
	      This  specifies  a  program which	is run (as root) after the au-
	      thentication process succeeds.  By default, no program  is  run.
	      The conventional name for	a file used here is Xstartup.  See the
	      section Startup Program.

       DisplayManager.DISPLAY.session
	      This specifies the session to be executed	(not running as	root).
	      By default,  /usr/local/bin/xterm	is run.	 The conventional name
	      is Xsession.  See	the section Session Program.

       DisplayManager.DISPLAY.reset
	      This specifies a program which is	run (as	root) after  the  ses-
	      sion  terminates.	  By  default, no program is run.  The conven-
	      tional name is Xreset.  See the section Reset Program.

       DisplayManager.DISPLAY.openDelay

       DisplayManager.DISPLAY.openRepeat

       DisplayManager.DISPLAY.openTimeout

       DisplayManager.DISPLAY.startAttempts
	      These numeric resources control the behavior  of	xdm  when  at-
	      tempting	to open	intransigent servers.  openDelay is the	length
	      of the pause (in seconds)	between	successive  attempts,  openRe-
	      peat  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 star-
	      tAttempts	is the number of times this entire process is done be-
	      fore  giving  up	on the server.	After openRepeat attempts have
	      been made, or if openTimeout seconds elapse  in  any  particular
	      attempt,	xdm  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	devel-
	      oped  and	 works quite well on most systems.  The	default	values
	      are 5 for	openDelay, 5 for openRepeat, 30	for openTimeout	and  4
	      for startAttempts.

       DisplayManager.DISPLAY.pingInterval

       DisplayManager.DISPLAY.pingTimeout
	      To  discover  when  remote  displays disappear, xdm occasionally
	      pings them, using	an X connection	and XSync calls.  pingInterval
	      specifies	the time (in minutes) between each ping	attempt, ping-
	      Timeout specifies	the maximum amount of  time  (in  minutes)  to
	      wait  for	the terminal to	respond	to the request.	 If the	termi-
	      nal does not respond, the	session	is declared  dead  and	termi-
	      nated.   By  default,  both  are	set to 5 minutes.  If you fre-
	      quently use X terminals which can	become isolated	from the  man-
	      aging 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.  xdm will not ping local displays.
	      Although it would	seem harmless, it is unpleasant	when the work-
	      station  session is terminated as	a result of the	server hanging
	      for NFS service and not responding to the	ping.

       DisplayManager.DISPLAY.terminateServer
	      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.''

       DisplayManager.DISPLAY.userPath
	      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/lo-
	      cal/bin:/usr/ucb''  is  a	common setting.	 The default value can
	      be specified at build time in the	X  system  configuration  file
	      with DefaultUserPath.

       DisplayManager.DISPLAY.systemPath
	      Xdm sets the PATH	environment variable for the startup and reset
	      scripts to the value of this resource.  The default for this re-
	      source is	specified at build time	by the DefaultSystemPath entry
	      in the system configuration file;	 ``/etc:/bin:/usr/bin:/usr/lo-
	      cal/bin:/usr/ucb''  is  a	 common	 choice.   Note	the absence of
	      ``.'' from this entry.  This is a	good practice  to  follow  for
	      root;  it	 avoids	 many  common  Trojan Horse system penetration
	      schemes.

       DisplayManager.DISPLAY.systemShell
	      Xdm sets the SHELL environment variable for the startup and  re-
	      set scripts to the value of this resource.  It is	/bin/sh	by de-
	      fault.

       DisplayManager.DISPLAY.failsafeClient
	      If the default session fails to execute, xdm will	fall  back  to
	      this  program.   This program is executed	with no	arguments, but
	      executes using the same environment  variables  as  the  session
	      would  have  had (see the	section	Session	Program).  By default,
	      /usr/local/bin/xterm is used.

       DisplayManager.DISPLAY.grabServer

       DisplayManager.DISPLAY.grabTimeout
	      To improve security, xdm 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	 keyboard  grab	 succeeds,  otherwise  the  server  is
	      grabbed  until  just  before the session begins.	The default is
	      ``false.''  The grabTimeout resource specifies the maximum  time
	      xdm  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, xdm kills	and restarts the server	(if  possible)
	      and the session.

       DisplayManager.DISPLAY.authorize

       DisplayManager.DISPLAY.authName
	      authorize	 is a boolean resource which controls whether xdm gen-
	      erates 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
	      dynamically  specify  which  authorization  mechanisms  are sup-
	      ported, so authName is ignored in	this case.  When authorize  is
	      set  for	a display 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-AUTHORIZATION-1 MIT-MAGIC-COOKIE-1.''

       DisplayManager.DISPLAY.authFile
	      This file	is used	to communicate the authorization data from xdm
	      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 Dis-
	      playManager.authDir and the name of the display.

       DisplayManager.DISPLAY.authComplain
	      If set to	``false,'' disables the	use of the unsecureGreeting in
	      the  login  window.  See the section Authentication Widget.  The
	      default is ``true.''

       DisplayManager.DISPLAY.resetSignal
	      The number of the	signal xdm sends to reset the server.  See the
	      section Controlling the Server.  The default is 1	(SIGHUP).

       DisplayManager.DISPLAY.termSignal
	      The number of the	signal xdm sends to terminate the server.  See
	      the  section  Controlling	 the  Server.	The  default   is   15
	      (SIGTERM).

       DisplayManager.DISPLAY.resetForAuth
	      The  original  implementation  of	 authorization	in  the	sample
	      server reread the	authorization file at server reset  time,  in-
	      stead of when checking the initial connection.  As xdm generates
	      the authorization	information just before	connecting to the dis-
	      play,  an	 old server would not get up-to-date authorization in-
	      formation.  This resource	causes	xdm  to	 send  SIGHUP  to  the
	      server  after  setting up	the file, causing an additional	server
	      reset to occur, during which time	the new	authorization informa-
	      tion  will  be  read.  The default is ``false,'' which will work
	      for all MIT servers.

       DisplayManager.DISPLAY.userAuthDir
	      When xdm is unable to write to the usual user authorization file
	      ($HOME/.Xauthority),  it	creates	a unique file name in this di-
	      rectory and points the environment variable  XAUTHORITY  at  the
	      created file.  It	uses /tmp by default.

CONFIGURATION FILE
       First,  the  xdm	configuration file should be set up.  Make a directory
       (usually	 /usr/local/share/examples/xdm)	to contain all of the relevant
       files.

       Here  is	a reasonable configuration file, which could be	named xdm-con-
       fig:

	    DisplayManager.servers:	       /usr/local/share/examples/xdm/Xservers
	    DisplayManager.errorLogFile:       /var/log/xdm.log
	    DisplayManager*resources:	       /usr/local/share/examples/xdm/Xresources
	    DisplayManager*startup:	       /usr/local/share/examples/xdm/Xstartup
	    DisplayManager*session:	       /usr/local/share/examples/xdm/Xsession
	    DisplayManager.pidFile:	       /var/run/xdm-pid
	    DisplayManager._0.authorize:       true
	    DisplayManager*authorize:	       false

       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 dis-
       play,  by  replacing the	``*'' with the display-name, but normally this
       is not very useful.  See	the Resources section for a  complete  discus-
       sion.

XDMCP ACCESS CONTROL
       The  database  file specified by	the DisplayManager.accessFile provides
       information which xdm uses to control access from  displays  requesting
       XDMCP  service.	 This  file  contains three types of entries:  entries
       which control the response to Direct  and  Broadcast  queries,  entries
       which control the response to Indirect queries, and macro definitions.

       The  format  of	the  Direct entries is simple, either a	host name or a
       pattern,	which is distinguished from a host name	by  the	 inclusion  of
       one  or	more  meta  characters	(`*' matches any sequence of 0 or more
       characters, and `?' matches any single character)  which	 are  compared
       against	the  host  name	of the display device.	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 pat-
       terns, 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 fol-
       lowed by	the optional ``NOBROADCAST'' keyword.  This  can  be  used  to
       prevent	an  xdm	 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 be
       sent.

       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 xdm	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	`\newline' causes the  newline
       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 excess.lcs.mit.edu kanga.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

       If compiled with	IPv6 support, multicast	address	groups may also	be in-
       cluded in the list of addresses indirect	queries	are set	to.  Multicast
       addresses  may be followed by an	optional / character and hop count. If
       no hop count is specified, the multicast	hop count defaults to 1, keep-
       ing  the	 packet	 on  the local network.	For IPv4 multicasting, the hop
       count is	used as	the TTL.

       Examples:

       rincewind.sample.net ff02::1		    #IPv6 Multicast to ff02::1
						    #with a hop	count of 1
       ponder.sample.net    CHOOSER 239.192.1.1/16  #Offer a menu of hosts
						    #who respond to IPv4 Multicast
						    # to 239.192.1.1 with a TTL	of 16

CHOOSER
       For X terminals that do not offer a host	menu for use with Broadcast or
       Indirect	 queries,  the	chooser	 program can do	this for them.	In the
       Xaccess file, specify ``CHOOSER'' as the	first entry  in	 the  Indirect
       host  list.  Chooser will send a	Query request to each of the remaining
       host names in the list and offer	a menu of all the hosts	that respond.

       The list	may consist of the word	``BROADCAST,'' in which	 case  chooser
       will  send a Broadcast instead, again offering a	menu of	all hosts that
       respond.	 Note that on some operating systems, UDP  packets  cannot  be
       broadcast, so this feature will not work.

       Example Xaccess file using chooser:

       extract.lcs.mit.edu  CHOOSER %HOSTS	    #offer a menu of these hosts
       xtra.lcs.mit.edu	    CHOOSER BROADCAST	    #offer a menu of all hosts

       The  program to use for chooser is specified by the DisplayManager.DIS-
       PLAY.chooser resource.  For more	flexibility at this step, the  chooser
       could  be  a  shell script.  Chooser is the session manager here; it is
       run instead of a	child xdm to manage the	display.

       Resources for this program can be put into the file named  by  Display-
       Manager.DISPLAY.resources.

       When  the user selects a	host, chooser prints the host chosen, which is
       read by the parent xdm, and exits.  xdm closes its connection to	the  X
       server, and the server resets and sends another Indirect	XDMCP request.
       xdm remembers the user's	choice (for DisplayManager.choiceTimeout  sec-
       onds)  and forwards the request to the chosen host, which starts	a ses-
       sion on that display.

LISTEN
       The following configuration directive is	also defined for  the  Xaccess
       configuration file:

       LISTEN interface	[list of multicast group addresses]
	      interface	 may  be a hostname or IP addresss representing	a net-
	      work interface on	this machine, or the wildcard *	 to  represent
	      all available network interfaces.

       If  one	or more	LISTEN lines are specified, xdm	only listens for XDMCP
       connections on the specified interfaces.	If multicast  group  addresses
       are  listed  on	a  listen  line, xdm joins the multicast groups	on the
       given interface.

       If no LISTEN lines are given, the original behavior of listening	on all
       interfaces  is preserved	for backwards compatibility.  Additionally, if
       no LISTEN is specified, xdm joins  the  default	XDMCP  IPv6  multicast
       group, when compiled with IPv6 support.

       To  disable listening for XDMCP connections altogther, a	line of	LISTEN
       with no addresses may be	specified, or the previously supported	method
       of setting DisplayManager.requestPort to	0 may be used.

       Examples:
       LISTEN *	ff02::1	   # Listen on all interfaces and to the
			   # ff02::1 IPv6 multicast group.
       LISTEN 10.11.12.13  # Listen only on this interface, as long
			   # as	no other listen	directives appear in
			   # file.

IPv6 MULTICAST ADDRESS SPECIFICATION
       The    Internet	 Assigned   Numbers   Authority	  has	has   assigned
       ff0X:0:0:0:0:0:0:12b as the permanently assigned	range of multicast ad-
       dresses	for  XDMCP.  The  X in the prefix may be replaced by any valid
       scope identifier, such as 1 for Node-Local, 2  for  Link-Local,	5  for
       Site-Local,  and	so on.	(See IETF RFC 2373 or its replacement for fur-
       ther details and	scope definitions.)  xdm defaults to listening on  the
       Link-Local scope	address	ff02:0:0:0:0:0:0:12b to	most closely match the
       old IPv4	subnet broadcast behavior.

LOCAL SERVER SPECIFICATION
       The resource DisplayManager.servers gives a server specification	or, if
       the  values  starts  with  a  slash  (/), the name of a file containing
       server specifications, one per line.

       Each specification indicates a display which should constantly be  man-
       aged  and  which	is not using XDMCP.  This method is used typically for
       local servers only.  If the resource or the file	named by the  resource
       is empty, xdm will offer	XDMCP service only.

       Each specification consists of at least three parts:  a display name, a
       display class, a	display	type, and (for local servers) a	 command  line
       to  start the server.  A	typical	entry for local	display	number 0 would
       be:

	 :0 Digital-QV local /usr/local/bin/X :0

       The display types are:

       local	 local display:	xdm must run the server
       foreign	 remote	display: xdm opens an X	connection to a	running	server

       The display name	must be	something that can be passed in	 the  -display
       option  to  an X	program.  This string is used to generate the display-
       specific	resource names,	so be careful to match the  names  (e.g.,  use
       ``:0  Sun-CG3 local /usr/local/bin/X :0'' instead of ``localhost:0 Sun-
       CG3 local /usr/local/bin/X :0'' if your other resources	are  specified
       as  ``DisplayManager._0.session'').   The display class portion is also
       used in the display-specific resources, as the class of	the  resource.
       This is useful if you have a large collection of	similar	displays (such
       as a corral of X	terminals) and would like to set resources for	groups
       of them.	 When using XDMCP, the display is required to specify the dis-
       play class, so the manual for your particular X terminal	 should	 docu-
       ment  the display class string for your device.	If it doesn't, you can
       run xdm in debug	mode and look at the resource strings which it	gener-
       ates for	that device, which will	include	the class string.

       When  xdm  starts  a  session,  it  sets	 up authorization data for the
       server.	For local  servers,  xdm  passes  ``-auth  filename''  on  the
       server's	command	line to	point it at its	authorization data.  For XDMCP
       servers,	xdm passes the authorization data to the server	via the	Accept
       XDMCP request.

RESOURCES FILE
       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:

	    xlogin*login.translations: #overrideCtrl<Key>R: abort-display()\n<Key>F1: set-session-argument(failsafe) finish-field()\n<Key>Return: set-session-argument() finish-field()

	    xlogin*borderWidth:	3
	    xlogin*greeting: CLIENTHOST
	    #ifdef COLOR
	    xlogin*greetColor: CadetBlue
	    xlogin*failColor: red
	    #endif

       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.

SETUP PROGRAM
       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 follow-
       ing 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 xdm 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  Display-
       Manager.DISPLAY.grabServer  is  set, Xsetup will	not be able to connect
       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:

	    #!/bin/sh
	    # Xsetup_0 - setup script for one workstation
	    xcmsdb < /usr/local/share/examples/xdm/monitors/alex.0
	    xconsole -geometry 480x130-0-0 -notify -verbose -exitOnFail	&

AUTHENTICATION WIDGET
       The  authentication widget prompts the user for the username, password,
       and/or other required authentication data from  the  keyboard.	Nearly
       every  imaginable  parameter  can  be  controlled with a	resource.  Re-
       sources for this	widget should be put into the file named  by  Display-
       Manager.DISPLAY.resources.   All	 of these have reasonable default val-
       ues, so it is not necessary to specify any of them.

       The resource file is loaded with	xrdb(1)	so it may  use	the  substitu-
       tions  defined  by that program such as CLIENTHOST for the client host-
       name in the login message, or C pre-processor #ifdef statements to pro-
       duce different displays depending on color depth	or other variables.

       Xdm  can	 be compiled with support for the Xft(3) library for font ren-
       dering.	 If this support is present, font faces	 are  specified	 using
       the resources with names	ending in "face" in the	fontconfig face	format
       described in the	Font Names section of  fonts.conf(5).	If  not,  then
       fonts  are specified using the resources	with names ending in "font" in
       the traditional X Logical Font Description format described in the Font
       Names section of	X(7).

       xlogin.Login.width, xlogin.Login.height,	xlogin.Login.x,	xlogin.Login.y
	      The  geometry of the Login widget	is normally computed automati-
	      cally.  If you wish to position it elsewhere,  specify  each  of
	      these resources.

       xlogin.Login.foreground
	      The color	used to	display	the input typed	by the user.

       xlogin.Login.face
	      The  face	used to	display	the input typed	by the user when built
	      with Xft support.	 The default is	``Serif-18''.

       xlogin.Login.font
	      The font used to display the input typed by the  user  when  not
	      built with Xft support.

       xlogin.Login.greeting
	      A	 string	which identifies this window.  The default is ``X Win-
	      dow System.''

       xlogin.Login.unsecureGreeting
	      When X authorization is requested	in the configuration file  for
	      this  display  and  none	is  in use, this greeting replaces the
	      standard greeting.  The default is ``This	is  an	unsecure  ses-
	      sion''

       xlogin.Login.greetFace
	      The  face	 used to display the greeting when built with Xft sup-
	      port.  The default is ``Serif-24:italic''.

       xlogin.Login.greetFont
	      The font used to display the greeting when not  built  with  Xft
	      support.

       xlogin.Login.greetColor
	      The color	used to	display	the greeting.

       xlogin.Login.namePrompt
	      The  string  displayed  to  prompt for a user name.  Xrdb	strips
	      trailing white space from	resource values, so to add  spaces  at
	      the end of the prompt (usually a nice thing), add	spaces escaped
	      with backslashes.	 The default is	``Login:  ''

       xlogin.Login.passwdPrompt
	      The string displayed to prompt for a password, when not using an
	      authentication system such as PAM	that provides its own prompts.
	      The default is ``Password:  ''

       xlogin.Login.promptFace
	      The face used to display prompts when built  with	 Xft  support.
	      The default is ``Serif-18:bold''.

       xlogin.Login.promptFont
	      The  font	 used  to display prompts when not built with Xft sup-
	      port.

       xlogin.Login.promptColor
	      The color	used to	display	prompts.

       xlogin.Login.changePasswdMessage
	      A	message	which is displayed when	the  users  password  has  ex-
	      pired.  The default is ``Password	Change Required''

       xlogin.Login.fail
	      A	message	which is displayed when	the authentication fails, when
	      not using	an authentication system such as PAM that provides its
	      own prompts.  The	default	is ``Login incorrect''

       xlogin.Login.failFace
	      The face used to display the failure message when	built with Xft
	      support.	The default is ``Serif-18:bold''.

       xlogin.Login.failFont
	      The font used to display the failure message when	not built with
	      Xft support.

       xlogin.Login.failColor
	      The color	used to	display	the failure message.

       xlogin.Login.failTimeout
	      The  number  of  seconds	that the failure message is displayed.
	      The default is 10.

       xlogin.Login.logoFileName
	      Name of an XPM format pixmap to display in the  greeter  window,
	      if built with XPM	support.   The default is no pixmap.

       xlogin.Login.logoPadding
	      Number of	pixels of space	between	the logo pixmap	and other ele-
	      ments of the greeter window, if the pixmap  is  displayed.   The
	      default is 5.

       xlogin.Login.useShape
	      If  set to ``true'', when	built with XPM support,	attempt	to use
	      the X Non-Rectangular Window Shape Extension to set  the	window
	      shape.  The default is ``true''.

       xlogin.Login.hiColor, xlogin.Login.shdColor
	      Raised  appearance  bezels may be	drawn around the greeter frame
	      and text input boxes by setting these resources.	hiColor	is the
	      highlight	 color,	 used  on the top and left sides of the	frame,
	      and the bottom and right sides of	text input  areas.    shdColor
	      is  the  shadow color, used on the bottom	and right sides	of the
	      frame, and the top and left sides	of text	input areas.  The  de-
	      fault for	both is	the foreground color, providing	a flat appear-
	      ance.

       xlogin.Login.frameWidth
	      frameWidth is the	width in pixels	of the area around the greeter
	      frame drawn in hiColor and shdColor.

       xlogin.Login.innerFramesWidth
	      innerFramesWidth	is the width in	pixels of the area around text
	      input areas drawn	in hiColor and shdColor.

       xlogin.Login.sepWidth
	      sepWidth is the width in pixels of the bezeled line between  the
	      greeting and input areas drawn in	hiColor	and shdColor.

       xlogin.Login.allowRootLogin
	      If  set  to ``false'', don't allow root (and any other user with
	      uid = 0) to log in directly.  The	default	is ``true''.

       xlogin.Login.allowNullPasswd
	      If set to	``true'', allow	an otherwise failing password match to
	      succeed  if the account does not require a password at all.  The
	      default is ``false'', so only users that have passwords assigned
	      can log in.

       xlogin.Login.translations
	      This  specifies the translations used for	the login widget.  Re-
	      fer to the X Toolkit documentation for a complete	discussion  on
	      translations.  The default translation table is:

		   Ctrl<Key>H:	  delete-previous-character() \nCtrl<Key>D:delete-character() \nCtrl<Key>B:move-backward-character() \nCtrl<Key>F:move-forward-character() \nCtrl<Key>A:move-to-begining() \nCtrl<Key>E:move-to-end() \nCtrl<Key>K:erase-to-end-of-line() \nCtrl<Key>U:erase-line() \nCtrl<Key>X:erase-line() \nCtrl<Key>C:restart-session() \nCtrl<Key>\\:abort-session() \n<Key>BackSpace:delete-previous-character()	\n<Key>Delete:delete-previous-character() \n<Key>Return:finish-field() \n<Key>:insert-char() .fi

       The actions which are supported by the widget are:

       delete-previous-character
	      Erases the character before the cursor.

       delete-character
	      Erases the character after the cursor.

       move-backward-character
	      Moves the	cursor backward.

       move-forward-character
	      Moves the	cursor forward.

       move-to-begining
	      (Apologies about the spelling error.)
	      Moves the	cursor to the beginning	of the editable	text.

       move-to-end
	      Moves the	cursor to the end of the editable text.

       erase-to-end-of-line
	      Erases all text after the	cursor.

       erase-line
	      Erases the entire	text.

       finish-field
	      If the cursor is in the name field, proceeds to the password field; if the
	      cursor is	in the password	field, checks the current name/password	pair.  If
	      the name/password	pair is	valid, xdm
	      starts the session.  Otherwise the failure message is displayed and
	      the user is prompted again.

       abort-session
	      Terminates and restarts the server.

       abort-display
	      Terminates the server, disabling it.  This action
	      is not accessible	in the default configuration.
	      There are	various	reasons	to stop	xdm on a system	console, such as
	      when shutting the	system down, when using	xdmshell,
	      to start another type of server, or to generally access the console.
	      Sending xdm a SIGHUP will	restart	the display.  See the section
	      Controlling XDM.

       restart-session
	      Resets the X server and starts a new session.  This can be used when
	      the resources have been changed and you want to test them	or when
	      the screen has been overwritten with system messages.

       insert-char
	      Inserts the character typed.

       set-session-argument
	      Specifies	a single word argument which is	passed to the session at startup.
	      See the section Session Program.

       allow-all-access
	      Disables access control in the server.  This can be used when
	      the .Xauthority file cannot be created by
	      xdm.
	      Be very careful using this;
	      it might be better to disconnect the machine from	the network
	      before doing this.

       On some systems (OpenBSD) the user's shell must be listed in
       /etc/shells
       to allow	login through xdm. The normal password and account expiration
       dates are enforced too.

STARTUP	PROGRAM
       The Xstartup program is run as root when	the user logs in.  It is typi-
       cally a shell script.  Since it is run as root, Xstartup	should be very
       careful	about  security.   This	is the place to	put commands which add
       entries to /etc/utmp (the sessreg program may be	 useful	 here),	 mount
       users'  home directories	from file servers, or abort the	session	if lo-
       gins are	not allowed.

       In addition to any specified by DisplayManager.exportList, the  follow-
       ing environment variables are passed:

	    DISPLAY	   the associated display name
	    HOME	   the initial working directory of the	user
	    LOGNAME	   the user name
	    USER	   the user name
	    PATH	   the value of	DisplayManager.DISPLAY.systemPath
	    SHELL	   the value of	DisplayManager.DISPLAY.systemShell
	    XAUTHORITY	   may be set to an authority file
	    WINDOWPATH	   may be set to the "window path" leading to the X server

       No arguments are	passed to the script.  Xdm waits until this script ex-
       its before starting the user session.  If the exit value	of this	script
       is  non-zero, xdm discontinues the session and starts another authenti-
       cation cycle.

       The sample Xstartup file	shown  here  prevents  login  while  the  file
       /etc/nologin exists.  Thus this is not a	complete example, but simply a
       demonstration of	the available functionality.

       Here is a sample	Xstartup script:

	    #!/bin/sh
	    #
	    # Xstartup
	    #
	    # This program is run as root after	the user is verified
	    #
	    if [ -f /etc/nologin ]; then
		 xmessage -file	/etc/nologin -timeout 30 -center
		 exit 1
	    fi
	    sessreg -a -l $DISPLAY -x /usr/local/share/examples/xdm/Xservers $LOGNAME
	    /usr/local/share/examples/xdm/GiveConsole
	    exit 0

SESSION	PROGRAM
       The Xsession program is the command which is run	as the user's session.
       It is run with the permissions of the authorized	user.

       In  addition to any specified by	DisplayManager.exportList, the follow-
       ing environment variables are passed:

	    DISPLAY	   the associated display name
	    HOME	   the initial working directory of the	user
	    LOGNAME	   the user name
	    USER	   the user name
	    PATH	   the value of	DisplayManager.DISPLAY.userPath
	    SHELL	   the user's default shell (from getpwnam)
	    XAUTHORITY	   may be set to a non-standard	authority file
	    KRB5CCNAME	   may be set to a Kerberos credentials	cache name
	    WINDOWPATH	   may be set to the "window path" leading to the X server

       At most installations, Xsession should look in $HOME for	a file	.xses-
       sion,  which  contains  commands	 that each user	would like to use as a
       session.	 Xsession should also implement	a system default session if no
       user-specified session exists.

       An  argument may	be passed to this program from the authentication wid-
       get using the `set-session-argument' action.  This can be used  to  se-
       lect  different	styles of session.  One	good use of this feature is to
       allow the user to escape	from the ordinary session when it fails.  This
       allows users to repair their own	.xsession if it	fails, without requir-
       ing administrative intervention.	 The  example  following  demonstrates
       this feature.

       This example recognizes the special ``failsafe''	mode, specified	in the
       translations in the Xresources file, to provide an escape from the  or-
       dinary session.	It also	requires that the .xsession file be executable
       so we don't have	to guess what shell it wants to	use.

	    #!/bin/sh
	    #
	    # Xsession
	    #
	    # This is the program that is run as the client
	    # for the display manager.

	    case $# in
	    1)
		 case $1 in
		 failsafe)
		      exec xterm -geometry 80x24-0-0
		      ;;
		 esac
	    esac

	    startup=$HOME/.xsession
	    resources=$HOME/.Xresources

	    if [ -f "$startup" ]; then
		 exec "$startup"
	    else
		 if [ -f "$resources" ]; then
		      xrdb -load "$resources"
		 fi
		 twm &
		 xman -geometry	+10-10 &
		 exec xterm -geometry 80x24+10+10 -ls
	    fi

       The user's .xsession file  might	 look  something  like	this  example.
       Don't forget that the file must have execute permission.
	    #! /bin/csh
	    # no -f in the previous line so .cshrc gets	run to set $PATH
	    twm	&
	    xrdb -merge	"$HOME/.Xresources"
	    emacs -geometry +0+50 &
	    xbiff -geometry -430+5 &
	    xterm -geometry -0+50 -ls

RESET PROGRAM
       Symmetrical with	Xstartup, the Xreset script is run after the user ses-
       sion has	terminated.  Run as root, it should contain commands that undo
       the effects of commands in Xstartup, removing entries from /etc/utmp or
       unmounting directories from file	servers.   The	environment  variables
       that were passed	to Xstartup are	also passed to Xreset.

       A sample	Xreset script:
	    #!/bin/sh
	    #
	    # Xreset
	    #
	    # This program is run as root after	the session ends
	    #
	    sessreg -d -l $DISPLAY -x /usr/local/share/examples/xdm/Xservers $LOGNAME
	    /usr/local/share/examples/xdm/TakeConsole
	    exit 0

CONTROLLING THE	SERVER
       Xdm  controls local servers using POSIX signals.	 SIGHUP	is expected to
       reset the server, closing all client connections	and  performing	 other
       cleanup duties.	SIGTERM	is expected to terminate the server.  If these
       signals do not perform the expected actions, the	resources  DisplayMan-
       ager.DISPLAY.resetSignal	  and	DisplayManager.DISPLAY.termSignal  can
       specify alternate signals.

       To control remote terminals not using XDMCP, xdm	 searches  the	window
       hierarchy on the	display	and uses the protocol request KillClient in an
       attempt to clean	up the terminal	for the	next session.	This  may  not
       actually	kill all of the	clients, as only those which have created win-
       dows will be noticed.  XDMCP provides a more sure mechanism;  when  xdm
       closes  its initial connection, the session is over and the terminal is
       required	to close all other connections.

CONTROLLING XDM
       Xdm responds to two signals: SIGHUP and SIGTERM.	 When sent  a  SIGHUP,
       xdm  rereads  the  configuration	file, the access control file, and the
       servers file.  For the servers file, it notices if  entries  have  been
       added  or removed.  If a	new entry has been added, xdm starts a session
       on the associated display.  Entries which have been  removed  are  dis-
       abled  immediately, meaning that	any session in progress	will be	termi-
       nated without notice and	no new session will be started.

       When sent a SIGTERM, xdm	terminates all sessions	in progress and	exits.
       This can	be used	when shutting down the system.

       Xdm attempts to mark its	various	sub-processes for ps(1)	by editing the
       command line argument list in place.  Because xdm can't allocate	 addi-
       tional space for	this task, it is useful	to start xdm with a reasonably
       long command line (using	the full path name should  be  enough).	  Each
       process which is	servicing a display is marked -display.

ADDITIONAL LOCAL DISPLAYS
       To  add	an additional local display, add a line	for it to the Xservers
       file.  (See the section Local Server Specification.)

       Examine the display-specific resources in xdm-config (e.g., DisplayMan-
       ager._0.authorize)  and consider	which of them should be	copied for the
       new display.  The default xdm-config has	all the	appropriate lines  for
       displays	:0 and :1.

OTHER POSSIBILITIES
       You  can	 use xdm to run	a single session at a time, using the 4.3 init
       options or other	suitable daemon	by specifying the server on  the  com-
       mand line:

	    xdm	-server	":0 SUN-3/60CG4	local /usr/local/bin/X :0"

       Or,  you	might have a file server and a collection of X terminals.  The
       configuration for this is identical to the  sample  above,  except  the
       Xservers	file would look	like

	    extol:0 VISUAL-19 foreign
	    exalt:0 NCD-19 foreign
	    explode:0 NCR-TOWERVIEW3000	foreign

       This  directs  xdm  to manage sessions on all three of these terminals.
       See the section Controlling Xdm for a description of using  signals  to
       enable and disable these	terminals in a manner reminiscent of init(8).

LIMITATIONS
       One  thing  that	 xdm isn't very	good at	doing is coexisting with other
       window systems.	To use multiple	window systems on the  same  hardware,
       you'll probably be more interested in xinit.

FILES
       /usr/local/share/examples/xdm/xdm-config
			   the default configuration file

       $HOME/.Xauthority   user	 authorization	file where xdm stores keys for
			   clients to read

       /usr/local/lib/X11/xdm/chooser
			   the default chooser

       /usr/local/bin/xrdb the default resource	database loader

       /usr/local/bin/X	   the default server

       /usr/local/bin/xterm
			   the default session program and failsafe client

       /usr/local/share/examples/xdm/A_display_-_suffix_
			   the default place for authorization files

       /tmp/K5C_display_   Kerberos credentials	cache

SEE ALSO
       X(7),   xinit(1),   xauth(1),   xrdb(1),	  Xsecurity(7),	   sessreg(1),
       Xserver(1), fonts.conf(5).
       X Display Manager Control Protocol

AUTHOR
       Keith Packard, MIT X Consortium

X Version 11			   xdm 1.1.8				XDM(1)

NAME | SYNOPSIS | DESCRIPTION | OVERVIEW | OPTIONS | RESOURCES | CONFIGURATION FILE | XDMCP ACCESS CONTROL | CHOOSER | LISTEN | IPv6 MULTICAST ADDRESS SPECIFICATION | LOCAL SERVER SPECIFICATION | RESOURCES FILE | SETUP PROGRAM | AUTHENTICATION WIDGET | STARTUP PROGRAM | SESSION PROGRAM | RESET PROGRAM | CONTROLLING THE SERVER | CONTROLLING XDM | ADDITIONAL LOCAL DISPLAYS | OTHER POSSIBILITIES | LIMITATIONS | FILES | SEE ALSO | AUTHOR

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