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.

X Version 11                                   xorg-server 21.1.18                                       XVFB(1)