Xvfb
(1)
Name
Xvfb - virtual framebuffer X server for X Version 11
Synopsis
/usr/bin/Xvfb [ option ] ...
Description
User Commands XVFB(1)
NAME
Xvfb - virtual framebuffer X server for X Version 11
SYNOPSIS
/usr/bin/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 pro-
cessing with Xvfb as a background rendering engine, load
testing, as an aid to porting the X server to a new plat-
form, 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 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
X Version 11 Last change: xorg-server 1.14.5 1
User Commands XVFB(1)
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 use-
ful 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 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 pre-
ceding example.
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User Commands XVFB(1)
SEE ALSO
X(5), Xserver(1), xwd(1), xwud(1), XWDFile.h
AUTHORS
David P. Wiggins, The Open Group, Inc.
ATTRIBUTES
See attributes(5) for descriptions of the following
attributes:
+-----------------------------+-----------------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+-----------------------------+-----------------------------+
|Availability |x11/server/xvfb |
+-----------------------------+-----------------------------+
|Interface Stability |Volatile |
+-----------------------------+-----------------------------+
X Version 11 Last change: xorg-server 1.14.5 3