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CentOS 7.0 - man page for xvfb (centos section 1)

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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 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 addi-
	   tion to the depths implied by the supported screens.  list-of-depths is a  space-sepa-
	   rated 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  pix-
	   elization 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  configuration  (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 configuration (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 1.15.0				  XVFB(1)
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