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
       mfb or cfb 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.


       To build Xvfb, put the following in your host.def and remake.

       #define BuildServer YES /∗ if you aren’t already building other servers
       #define XVirtualFramebufferServer YES


       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 cfb and mfb 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 /usr/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 /usr/tmp for the framebuffer.

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


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


       David P. Wiggins, The Open Group, Inc.


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