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 dis-
       play 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  exer-
       cised  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.

BUILDING
       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

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  respectively.
           By  default,  only  screen 0 exists and has the dimen-
           sions 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  mem-
           ory  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 mem-
           ory  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 exper-
           iment 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.

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  for-
           mat.   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  configura-
               tion  (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 configura-
               tion (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 example.

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

AUTHORS
       David P. Wiggins, X Consortium, Inc.