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XVFB(1)			    General Commands Manual		       XVFB(1)

       Xvfb - virtual framebuffer X server for X Version 11

       Xvfb [ option ] ...

       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
       mfb or cfb 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 un-
       obtrusive way to	run applications that don't really need	 an  X	server
       but insist on having one	anyway.

       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

       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 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.

	   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	inter-

       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 cfb and mfb code.

       -blackpixel pixel-value,	-whitepixel pixel-value
	   These  options  specify the black and white pixel values the	server
	   should use.

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

	   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  re-
	   sulting snapshot will even contain the cursor image.

       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 /usr/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 /usr/tmp	for the	framebuffer.

       xwud -in	/usr/tmp/Xvfb_screen0
	       Displays	 screen	0 of the server	started	by the preceding exam-

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

       David P.	Wiggins, The Open Group, Inc.



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