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
           respectively.  By default, only screen 0 exists and has the dimensions 1280x1024x24.

       -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 1600x1200x24
               The server will listen for connections as server  number  1,  and  screen  0  will  be  depth  24
               1600x1200.

       Xvfb :1 -screen 1 1600x1200x16
               The  server will listen for connections as server number 1, screen 0 will have the default screen
               configuration (1280x1024x24), 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, 1280x1024x24), 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.