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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
       fb code for any depth can be exercised with  this  server  without  the
       need  for real hardware that supports the desired depths.  The X	commu-
       nity 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.

       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 fb 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 /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	 exam-

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

       David P.	Wiggins, The Open Group, Inc.

X Version 11		      xorg-server 1.14.7		       XVFB(1)


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