bionic (1) Xserver.1.gz

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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.