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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.

       -background none
               Asks the driver not to clear the background on startup,  if  the  driver  supports
               that.   May  be  useful for smooth transition with eg. fbdev driver.  For security
               reasons this is not the default as the screen contents might show a previous  user
               session.

       -br     sets  the  default  root  window to solid black instead of the standard root weave
               pattern.   This is the default unless -retro or -wr is specified.

       -bs     disables backing store support on all screens.

       -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.

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

       -displayfd fd
               specifies  a  file  descriptor  in  the  launching process.  Rather than specify a
               display number, the X server will attempt to listen on successively higher display
               numbers,  and  upon finding a free one, will write the display number back on this
               file descriptor as a newline-terminated string.  The -pn option  is  ignored  when
               using -displayfd.

       -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 beep (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.

       -iglx   Prohibit creating indirect GLX contexts.  Indirect GLX is of limited use, since it
               lacks  support  for  many  modern OpenGL features and extensions; it's slower than
               direct contexts; and it opens a large attack surface for protocol parsing  errors.
               This is the default unless +iglx is specified.

       +iglx   Allow creating indirect GLX contexts.

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

       -nocursor
               disable the display of the pointer cursor.

       -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.  Supported transport types are platform dependent, but
               commonly include:

               tcp     TCP over IPv4 or IPv6
               inet    TCP over IPv4 only
               inet6   TCP over IPv6 only
               unix    UNIX Domain Sockets
               local   Platform preferred local connection method

       -listen trans-type
               enables a transport type.  For example, TCP/IP connections  can  be  enabled  with
               -listen  tcp.   This  option  may  be issued multiple times to enable 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 server 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 kdrive servers, this  implies
               -zap.

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

       -su     disables save under support on all screens.

       -seat seat
               seat  to  run on. Takes a string identifying a seat in a platform specific syntax.
               On platforms which support this feature this may be used to limit  the  server  to
               expose only a specific subset of devices connected to the system.

       -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.

       -maxclients
               64|128|256|512 Set the maximum number of clients  allowed  to  connect  to  the  X
               server.  Acceptable values are 64, 128, 256 or 512.

       -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.

       [+-]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: TCP/IP,  Unix  Domain  sockets,  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 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
               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,built-
       ins .

       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 'unscaled',
       second FPE will be /usr/share/X11/fonts/75dpi, also with  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/share/fonts/X11/misc,/usr/share/fonts/X11/75dpi,/usr/share/fonts/X11/100dpi
                                     Bitmap font directories

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

       /tmp/.X11-unix/Xn             Unix domain socket 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

       Keyboards: xkeyboard-config(7)

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

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

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

       Server-specific man pages: Xorg(1), Xdmx(1),  Xephyr(1),  Xnest(1),  Xvfb(1),  Xquartz(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.