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NAME

       Xserver - X Window System display server

SYNOPSIS

       X [option ...]

DESCRIPTION

       X  is  the  generic name for the X Window System display server.  It is
       frequently a link or a  copy  of  the  appropriate  server  binary  for
       driving the most frequently used server on a given machine.

STARTING THE SERVER

       The  X  server  is  usually  started from the X Display Manager program
       xdm(1) or a similar display manager program.  This utility is run  from
       the  system  boot  files  and takes care of keeping the server running,
       prompting for  usernames  and  passwords,  and  starting  up  the  user
       sessions.

       Installations  that run more than one window system may need to use the
       xinit(1) utility instead of a display manager.  However, xinit is to be
       considered  a tool for building startup scripts and is not intended for
       use by end users.  Site administrators are  strongly  urged  to  use  a
       display manager, or build other interfaces for novice users.

       The  X  server  may  also  be started directly by the user, though this
       method is usually reserved for  testing  and  is  not  recommended  for
       normal  operation.   On  some  platforms,  the  user  must have special
       permission to start the X  server,  often  because  access  to  certain
       devices (e.g. /dev/mouse) is restricted.

       When  the  X server starts up, it typically takes over the display.  If
       you are running on a workstation whose console is the display, you  may
       not be able to log into the console while the server is running.

OPTIONS

       Many  X  servers  have  device-specific  command line options.  See the
       manual pages for the individual servers for more  details;  a  list  of
       server-specific manual pages is provided in the SEE ALSO section below.

       All of the X servers accept the command line options  described  below.
       Some  X  servers  may have alternative ways of providing the parameters
       described here, but the values provided via the  command  line  options
       should override values specified via other mechanisms.

       :displaynumber
               The  X server runs as the given displaynumber, which by default
               is 0.  If multiple X servers are to  run  simultaneously  on  a
               host,  each must have a unique display number.  See the DISPLAY
               NAMES section of the X(7) manual page to learn how  to  specify
               which display number clients should try to use.

       -a number
               sets  pointer  acceleration  (i.e.  the  ratio  of  how much is
               reported to how much the user actually moved the pointer).

       -ac     disables host-based access control mechanisms.  Enables  access
               by  any host, and permits any host to modify the access control
               list.  Use with extreme caution.  This option exists  primarily
               for running test suites remotely.

       -audit level
               sets  the  audit  trail level.  The default level is 1, meaning
               only connection rejections are reported.  Level 2  additionally
               reports  all  successful  connections and disconnects.  Level 4
               enables messages  from  the  SECURITY  extension,  if  present,
               including  generation  and  revocation  of  authorizations  and
               violations of the security policy.  Level 0 turns off the audit
               trail.  Audit lines are sent as standard error output.

       -auth authorization-file
               specifies  a  file which contains a collection of authorization
               records used to authenticate access.  See also the  xdm(1)  and
               Xsecurity(7) manual pages.

       -bs     disables backing store support on all screens.

       -br     sets  the  default  root  window  to solid black instead of the
               standard root weave pattern.

       -c      turns off key-click.

       c volume
               sets key-click volume (allowable range: 0-100).

       -cc class
               sets the visual class for the root  window  of  color  screens.
               The  class  numbers  are  as  specified in the X protocol.  Not
               obeyed by all servers.

       -co filename
               sets  name   of   RGB   color   database.    The   default   is
               /usr/share/X11/rgb.

       -core   causes the server to generate a core dump on fatal errors.

       -deferglyphs whichfonts
               specifies  the  types  of  fonts  for  which  the server should
               attempt to use deferred glyph loading.  whichfonts can  be  all
               (all fonts), none (no fonts), or 16 (16 bit fonts only).

       -dpi resolution
               sets  the  resolution for all screens, in dots per inch.  To be
               used when the server cannot determine the screen  size(s)  from
               the hardware.

       dpms    enables   DPMS   (display  power  management  services),  where
               supported.  The default state  is  platform  and  configuration
               specific.

       -dpms   disables DPMS (display power management services).  The default
               state is platform and configuration specific.

       -extensionextensionName
               disables named extension.   If an  unknown  extension  name  is
               specified, a list of accepted extension names is printed.

       +extensionextensionName
               enables  named  extension.    If  an  unknown extension name is
               specified, a list of accepted extension names is printed.

       -f volume
               sets feep (bell) volume (allowable range: 0-100).

       -fc cursorFont
               sets default cursor font.

       -fn font
               sets the default font.

       -fp fontPath
               sets the search path for fonts.  This path is a comma separated
               list  of  directories  which  the  X  server  searches for font
               databases.  See the FONTS section of this manual page for  more
               information and the default list.

       -help   prints a usage message.

       -I      causes all remaining command line arguments to be ignored.

       -maxbigreqsize size
               sets the maximum big request to size MB.

       -nolisten trans-type
               disables a transport type.  For example, TCP/IP connections can
               be disabled with -nolisten tcp.   This  option  may  be  issued
               multiple  times  to  disable  listening  to different transport
               types.

       -noreset
               prevents a server reset when  the  last  client  connection  is
               closed.   This  overrides  a  previous  -terminate command line
               option.

       -p minutes
               sets screen-saver pattern cycle time in minutes.

       -pn     permits the server to continue running if it fails to establish
               all  of its well-known sockets (connection points for clients),
               but establishes at least one.  This option is set by default.

       -nopn   causes the server to exit if it fails to establish all  of  its
               well-known sockets (connection points for clients).

       -r      turns off auto-repeat.

       r       turns on auto-repeat.

       -retro  starts the stipple with the classic stipple and cursor visible.
               The default is to start  with  a  black  root  window,  and  to
               suppress  display  of  the  cursor  until  the  first  time  an
               application calls XDefineCursor().  For the Xorg  server,  this
               also  changes the default for the DontZap option to FALSE.  For
               kdrive servers, this implies -zap.

       -s minutes
               sets screen-saver timeout time in minutes.

       -su     disables save under support on all screens.

       -t number
               sets pointer acceleration threshold in pixels (i.e.  after  how
               many pixels pointer acceleration should take effect).

       -terminate
               causes  the  server  to  terminate  at server reset, instead of
               continuing to run.  This overrides a previous -noreset  command
               line option.

       -to seconds
               sets default connection timeout in seconds.

       -tst    disables   all   testing   extensions   (e.g.,   XTEST,  XTrap,
               XTestExtension1, RECORD).

       ttyxx   ignored, for servers started the ancient way (from init).

       v       sets video-off screen-saver preference.

       -v      sets video-on screen-saver preference.

       -wm     forces  the  default  backing-store  of  all  windows   to   be
               WhenMapped.  This is a backdoor way of getting backing-store to
               apply to all windows.  Although all mapped  windows  will  have
               backing  store,  the  backing store attribute value reported by
               the server for a window will be the last value established by a
               client.   If it has never been set by a client, the server will
               report the default value, NotUseful.  This behavior is required
               by  the  X  protocol,  which  allows  the  server to exceed the
               client’s backing store expectations but does not provide a  way
               to tell the client that it is doing so.

       -wr     sets  the  default  root  window  to solid white instead of the
               standard root weave pattern.

       -x extension
               loads the specified extension at init.  This  is  a  no-op  for
               most implementations.

       [+-]xinerama
               enables(+)  or disables(-) the XINERAMA extension.  The default
               state is platform and configuration specific.

SERVER DEPENDENT OPTIONS

       Some X servers accept the following options:

       -ld kilobytes
               sets the data space limit of the server to the specified number
               of  kilobytes.  A value of zero makes the data size as large as
               possible.  The default value of -1 leaves the data space  limit
               unchanged.

       -lf files
               sets  the  number-of-open-files  limit  of  the  server  to the
               specified number.  A value of zero makes the limit as large  as
               possible.   The default value of -1 leaves the limit unchanged.

       -ls kilobytes
               sets the stack space limit  of  the  server  to  the  specified
               number  of  kilobytes.  A value of zero makes the stack size as
               large as possible.  The default value of -1  leaves  the  stack
               space limit unchanged.

       -logo   turns  on the X Window System logo display in the screen-saver.
               There is currently no way to change this from a client.

       nologo  turns off the X Window System logo display in the screen-saver.
               There is currently no way to change this from a client.

       -render default|mono|gray|color  sets  the color allocation policy that
               will be used by the render extension.

               default selects the default  policy  defined  for  the  display
                       depth of the X server.

               mono    don’t use any color cell.

               gray    use  a  gray  map  of  13  color cells for the X render
                       extension.

               color   use a color cube of at most 4*4*4 colors  (that  is  64
                       color cells).

       -dumbSched
               disables  smart  scheduling on platforms that support the smart
               scheduler.

       -schedInterval interval
               sets the smart  scheduler’s  scheduling  interval  to  interval
               milliseconds.

XDMCP OPTIONS

       X  servers  that  support  XDMCP have the following options.  See the X
       Display Manager Control Protocol specification for more information.

       -query hostname
               enables  XDMCP  and  sends  Query  packets  to  the   specified
               hostname.

       -broadcast
               enable  XDMCP  and  broadcasts  BroadcastQuery  packets  to the
               network.  The first responding display manager will  be  chosen
               for the session.

       -multicast [address [hop count]]
               Enable  XDMCP  and  multicast  BroadcastQuery  packets  to  the
               network.  The first responding display manager  is  chosen  for
               the session.  If an address is specified, the multicast is sent
               to that address.  If no address is specified, the multicast  is
               sent to the default XDMCP IPv6 multicast group.  If a hop count
               is specified, it is used as  the  maximum  hop  count  for  the
               multicast.   If no hop count is specified, the multicast is set
               to a maximum of 1 hop, to  prevent  the  multicast  from  being
               routed beyond the local network.

       -indirect hostname
               enables  XDMCP  and send IndirectQuery packets to the specified
               hostname.

       -port port-number
               uses the specified port-number for XDMCP  packets,  instead  of
               the  default.  This option must be specified before any -query,
               -broadcast, -multicast, or -indirect options.

       -from local-address
               specifies the local address to  connect  from  (useful  if  the
               connecting  host  has multiple network interfaces).  The local-
               address may be expressed in any form  acceptable  to  the  host
               platform’s gethostbyname(3) implementation.

       -once   causes  the  server  to  terminate (rather than reset) when the
               XDMCP session ends.

       -class display-class
               XDMCP has an additional  display  qualifier  used  in  resource
               lookup  for  display-specific  options.   This option sets that
               value, by default it is "MIT-Unspecified" (not  a  very  useful
               value).

       -cookie xdm-auth-bits
               When  testing  XDM-AUTHENTICATION-1,  a  private  key is shared
               between the server and the manager.  This option sets the value
               of that private data (not that it is very private, being on the
               command line!).

       -displayID display-id
               Yet another XDMCP specific value, this one allows  the  display
               manager  to  identify  each  display  so that it can locate the
               shared key.

XKEYBOARD OPTIONS

       X servers that support the XKEYBOARD (a.k.a.  "XKB")  extension  accept
       the  following options.  All layout files specified on the command line
       must be located in the  XKB  base  directory  or  a  subdirectory,  and
       specified  as  the  relative  path  from  the  XKB base directory.  The
       default XKB base directory is /usr/lib/X11/xkb.

       [+-]kb  enables(+) or disables(-) the XKEYBOARD extension.

       [+-]accessx [ timeout [ timeout_mask [ feedback [ options_mask ] ] ] ]
               enables(+) or disables(-) AccessX key sequences.

       -xkbdir directory
               base directory for keyboard layout files.  This option  is  not
               available  for setuid X servers (i.e., when the X server’s real
               and effective uids are different).

       -ardelay milliseconds
               sets the autorepeat delay (length of time in milliseconds  that
               a key must be depressed before autorepeat starts).

       -arinterval milliseconds
               sets  the  autorepeat  interval (length of time in milliseconds
               that should elapse between autorepeat-generated keystrokes).

       -xkbmap filename
               loads keyboard description in filename on server startup.

NETWORK CONNECTIONS

       The X server  supports  client  connections  via  a  platform-dependent
       subset  of  the  following transport types: TCPIP, Unix Domain sockets,
       DECnet, and several varieties  of  SVR4  local  connections.   See  the
       DISPLAY  NAMES  section of the X(7) manual page to learn how to specify
       which transport type clients should try to use.

GRANTING ACCESS

       The X server implements a platform-dependent subset  of  the  following
       authorization  protocols: MIT-MAGIC-COOKIE-1, XDM-AUTHORIZATION-1, XDM-
       AUTHORIZATION-2, SUN-DES-1, and MIT-KERBEROS-5.  See  the  Xsecurity(7)
       manual page for information on the operation of these protocols.

       Authorization  data  required  by  the above protocols is passed to the
       server in a private file named with  the  -auth  command  line  option.
       Each  time  the  server is about to accept the first connection after a
       reset (or when the server is starting), it reads this  file.   If  this
       file  contains  any  authorization  records,  the  local  host  is  not
       automatically allowed access to the server, and only clients which send
       one  of  the  authorization  records  contained  in  the  file  in  the
       connection setup information will  be  allowed  access.   See  the  Xau
       manual  page  for a description of the binary format of this file.  See
       xauth(1) for maintenance of this file, and distribution of its contents
       to remote hosts.

       The  X  server  also uses a host-based access control list for deciding
       whether or not to accept  connections  from  clients  on  a  particular
       machine.   If no other authorization mechanism is being used, this list
       initially consists of the host on which the server is running  as  well
       as  any  machines  listed  in  the  file  /etc/Xn.hosts, where n is the
       display number of the server.  Each line of  the  file  should  contain
       either  an  Internet  hostname  (e.g.  expo.lcs.mit.edu)  or  a  DECnet
       hostname in double colon format (e.g. hydra::) or a  complete  name  in
       the format family:name as described in the xhost(1) manual page.  There
       should be no leading or trailing spaces on any lines.  For example:

               joesworkstation
               corporate.company.com
               star::
               inet:bigcpu
               local:

       Users can add or remove hosts from this  list  and  enable  or  disable
       access  control  using  the  xhost command from the same machine as the
       server.

       If the X FireWall Proxy (xfwp) is  being  used  without  a  sitepolicy,
       host-based  authorization  must  be turned on for clients to be able to
       connect to the X server via  the  xfwp.   If  xfwp  is  run  without  a
       configuration  file and thus no sitepolicy is defined, if xfwp is using
       an X server  where  xhost  +  has  been  run  to  turn  off  host-based
       authorization  checks,  when a client tries to connect to this X server
       via xfwp, the X server will deny the connection.  See xfwp(1) for  more
       information about this proxy.

       The  X  protocol  intrinsically  does  not  have  any  notion of window
       operation permissions or place any restrictions on what  a  client  can
       do;  if  a  program  can  connect  to a display, it has full run of the
       screen.  X servers that support  the  SECURITY  extension  fare  better
       because  clients can be designated untrusted via the authorization they
       use to connect; see the xauth(1) manual page for details.  Restrictions
       are imposed on untrusted clients that curtail the mischief they can do.
       See the SECURITY extension specification for a complete list  of  these
       restrictions.

       Sites  that  have better authentication and authorization systems might
       wish to make use of the hooks  in  the  libraries  and  the  server  to
       provide additional security models.

SIGNALS

       The X server attaches special meaning to the following signals:

       SIGHUP  This   signal   causes   the   server  to  close  all  existing
               connections, free all resources, and restore all defaults.   It
               is  sent  by  the display manager whenever the main user’s main
               application (usually an xterm or window manager) exits to force
               the server to clean up and prepare for the next user.

       SIGTERM This signal causes the server to exit cleanly.

       SIGUSR1 This signal is used quite differently from either of the above.
               When the server starts, it checks to see if  it  has  inherited
               SIGUSR1 as SIG_IGN instead of the usual SIG_DFL.  In this case,
               the server sends a SIGUSR1 to its parent process after  it  has
               set  up  the various connection schemes.  Xdm uses this feature
               to recognize when connecting to the server is possible.

FONTS

       The X server  can  obtain  fonts  from  directories  and/or  from  font
       servers.   The  list  of directories and font servers the X server uses
       when trying to open a font is controlled by the font path.

       The     default     font     path     is     /usr/share/fonts/X11/misc,
       /usr/share/fonts/X11/cyrillic,   /usr/share/fonts/X11/100dpi/:unscaled,
       /usr/share/fonts/X11/75dpi/:unscaled,       /usr/share/fonts/X11/Type1,
       /usr/share/fonts/X11/100dpi,                /usr/share/fonts/X11/75dpi,
       /var/lib/defoma/x-ttcidfont-conf.d/dirs/TrueType .

       A special kind of directory  can  be  specified  using  the  catalogue:
       prefix. Directories specified this way can contain symlinks pointing to
       the real font directories. See the FONTPATH.D section for details.

       The font path can be set with the -fp option or by  xset(1)  after  the
       server has started.

FONTPATH.D

       You   can   specify   a   special   kind  of  font  path  in  the  form
       catalogue:<dir>.  The directory specified after the  catalogue:  prefix
       will be scanned for symlinks and each symlink destination will be added
       as a local fontfile FPE.

       The symlink can be suffixed by attributes  such  as  ’unscaled’,  which
       will  be  passed  through  to  the  underlying  fontfile  FPE. The only
       exception is the newly introduced ’pri’ attribute, which will  be  used
       for ordering the font paths specified by the symlinks.

       An example configuration:

           75dpi:unscaled:pri=20 -> /usr/share/X11/fonts/75dpi
           ghostscript:pri=60 -> /usr/share/fonts/default/ghostscript
           misc:unscaled:pri=10 -> /usr/share/X11/fonts/misc
           type1:pri=40 -> /usr/share/X11/fonts/Type1
           type1:pri=50 -> /usr/share/fonts/default/Type1

       This  will  add  /usr/share/X11/fonts/misc  as  the  first FPE with the
       attribute the attribute unscaled etc. This is  functionally  equivalent
       to setting the following font path:

           /usr/share/X11/fonts/misc:unscaled,
           /usr/share/X11/fonts/75dpi:unscaled,
           /usr/share/X11/fonts/Type1,
           /usr/share/fonts/default/Type1,
           /usr/share/fonts/default/ghostscript

FILES

       /etc/Xn.hosts                 Initial  access  control list for display
                                     number n

       /usr/lib/X11/fonts/misc,/usr/lib/X11/fonts/75dpi,/usr/lib/X11/fonts/100dpi
                                     Bitmap font directories

       /usr/lib/X11/fonts/TTF,/usr/lib/X11/fonts/Type1
                                     Outline font directories

       /usr/share/X11/rgb.txt        Color database

       /tmp/.X11-unix/Xn             Unix domain socket for display number n

       /tmp/rcXn                     Kerberos  5  replay  cache  for   display
                                     number n

       /usr/adm/Xnmsgs               Error  log  file  for display number n if
                                     run from init(8)

       /usr/lib/X11/xdm/xdm-errors   Default error log file if the  server  is
                                     run from xdm(1)

SEE ALSO

       General information: X(7)

       Protocols:  X  Window  System  Protocol, The X Font Service Protocol, X
       Display Manager Control Protocol

       Fonts: bdftopcf(1), mkfontdir(1), mkfontscale(1), xfs(1),  xlsfonts(1),
       xfontsel(1), xfd(1), X Logical Font Description Conventions

       Security:  Xsecurity(7),  xauth(1),  Xau(1), xdm(1), xhost(1), xfwp(1),
       Security Extension Specification

       Starting the server: xdm(1), xinit(1)

       Controlling the server once started: xset(1), xsetroot(1), xhost(1)

       Server-specific  man  pages:  Xorg(1),  Xdmx(1),   Xnest(1),   Xvfb(1),
       XDarwin(1), XWin(1).

       Server  internal documentation: Definition of the Porting Layer for the
       X v11 Sample Server

AUTHORS

       The sample server was originally written by Susan Angebranndt,  Raymond
       Drewry,  Philip  Karlton,  and  Todd  Newman,  from  Digital  Equipment
       Corporation, with support  from  a  large  cast.   It  has  since  been
       extensively  rewritten  by  Keith  Packard and Bob Scheifler, from MIT.
       Dave Wiggins took over post-R5 and made substantial improvements.