Xvfb - virtual framebuffer X server for X Version 11


   Xvfb [ option ] ...


   Xvfb  is  an X server that can run on machines with no display hardware
   and no physical input devices.  It emulates a  dumb  framebuffer  using
   virtual memory.

   The  primary use of this server was intended to be server testing.  The
   fb code for any depth can be exercised with  this  server  without  the
   need  for  real  hardware  that  supports  the  desired  depths.  The X
   community has found many other novel uses for Xvfb,  including  testing
   clients  against  unusual depths and screen configurations, doing batch
   processing with Xvfb as a background rendering engine, load testing, as
   an  aid  to  porting  the  X server to a new platform, and providing an
   unobtrusive way to run applications that don't really need an X  server
   but insist on having one anyway.


   In  addition  to  the normal server options described in the Xserver(1)
   manual page, Xvfb accepts the following command line switches:

   -screen screennum WxHxD
       This option creates screen screennum and sets  its  width,  height,
       and  depth  to W, H, and D respectively.  By default, only screen 0
       exists and has the dimensions 1280x1024x8.

   -pixdepths list-of-depths
       This option specifies a list  of  pixmap  depths  that  the  server
       should  support  in addition to the depths implied by the supported
       screens.  list-of-depths is a space-separated list of integers that
       can have values from 1 to 32.

   -fbdir framebuffer-directory
       This  option  specifies  the  directory  in which the memory mapped
       files containing the framebuffer memory  should  be  created.   See
       FILES.   This option only exists on machines that have the mmap and
       msync system calls.

       This option specifies that the framebuffer should be put in  shared
       memory.   The  shared  memory ID for each screen will be printed by
       the server.  The shared memory is in xwd format.  This option  only
       exists  on  machines  that  support  the  System  V  shared  memory

   If neither -shmem nor -fbdir is specified, the framebuffer memory  will
   be allocated with malloc().

   -linebias n
       This option specifies how to adjust the pixelization of thin lines.
       The value n is a bitmask of octants in which  to  prefer  an  axial
       step  when  the Bresenham error term is exactly zero.  See the file
       Xserver/mi/miline.h for more information.  This option is  probably
       only  useful  to  server developers to experiment with the range of
       line pixelization possible with the fb code.

   -blackpixel pixel-value, -whitepixel pixel-value
       These options specify the black and white pixel values  the  server
       should use.


   The following files are created if the -fbdir option is given.

       Memory  mapped  file  containing screen n's framebuffer memory, one
       file per screen.  The file is in xwd format.  Thus, taking a  full-
       screen  snapshot  can  be  done  with  a file copy command, and the
       resulting snapshot will even contain the cursor image.


   Xvfb :1 -screen 0 1600x1200x32
           The server will listen for connections as server number 1,  and
           screen 0 will be depth 32 1600x1200.

   Xvfb :1 -screen 1 1600x1200x16
           The server will listen for connections as server number 1, will
           have   the   default   screen   configuration   (one    screen,
           1280x1024x8), and screen 1 will be depth 16 1600x1200.

   Xvfb -pixdepths 3 27 -fbdir /var/tmp
           The server will listen for connections as server number 0, will
           have   the   default   screen   configuration   (one    screen,
           1280x1024x8),  will also support pixmap depths of 3 and 27, and
           will use memory mapped files in /var/tmp for the framebuffer.

   xwud -in /var/tmp/Xvfb_screen0
           Displays screen 0  of  the  server  started  by  the  preceding


   X(7), Xserver(1), xwd(1), xwud(1), XWDFile.h


   David P. Wiggins, The Open Group, Inc.


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