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Xvfb(1)                                                                Xvfb(1)


       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 commu-
       nity 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 inter-

       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  exam-


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


       David P. Wiggins, The Open Group, Inc.

X Version 11                   xorg-server 1.6.0                       Xvfb(1)

Mac OS X 10.6 X11 - Generated Sun Mar 7 12:28:52 CST 2010
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