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XVFB(1)                                                                                              XVFB(1)



NAME
       Xvfb - virtual framebuffer X server for X Version 11

SYNOPSIS
       Xvfb [ option ] ...

DESCRIPTION
       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.

OPTIONS
       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 respec-tively. respectively.
           tively.  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.

       -shmem
           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 interface.

       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.

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

       framebuffer-directory/Xvfb_screen<n>
           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.

EXAMPLES
       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 con-figuration configuration
               figuration (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  con-figuration configuration
               figuration  (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 example.

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

AUTHORS
       David P. Wiggins, The Open Group, Inc.



X Version 11                                  xorg-server 1.6.0                                      XVFB(1)