X(1) X(1)
NAME
X - UnixWare X Window System X11R5 display server
SYNOPSIS
X [:displaynumber] [-option ...] [ttyname]
DESCRIPTION
X is the generic name for the X Window System server. It is
frequently a link or a copy of the appropriate server binary
for driving the most frequently used server on a given
machine.
Starting the Server
The server is usually started from the X Display Manager
program xdm. This utility is run from the system boot files
and takes care of keeping the server running, prompting for
usernames and passwords, and starting up the user sessions.
It is easily configured for sites that wish to provide nice,
consistent interfaces for novice users (loading convenient
sets of resources, starting up a window manager, clock, and
nice selection of terminal emulator windows).
Installations that run more than one window system will still
need to use the xinit utility. However, xinit is to be
considered a tool for building startup scripts and is not
intended for use by end users. Site administrators are
strongly urged to use xdm, or build other interfaces for
novice users.
When the X server starts up, it takes over the display. If
you are running on a workstation whose console is the display,
you cannot log into the console while the server is running.
NETWORK CONNECTIONS
The X server supports connections made using the following
reliable byte-streams:
TCP/IP
The server listens on port 6000+n, where n is the display
number.
Unix Domain
The X server uses /tmp/.X11-unix/Xn as the filename for
the socket, where n is the display number.
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OPTIONS
The X server accepts the following command line options:
-a number
sets pointer acceleration (i.e. the ratio of how much
is reported to how much the user actually moved the
pointer).
-ac disables host-based access control mechanisms.
Enables access by any host, and permits any host to
modify the access control list. Use with extreme
caution. This option exists primarily for running
test suites remotely.
-authauthorization-file
specifies a file which contains a collection of
authorization records used to authenticate access.
See also the xdm and Xsecurity manual pages.
bc disables certain kinds of error checking, for bug
compatibility with previous releases (e.g., to work
around bugs in R2 and R3 xterms and toolkits).
Deprecated.
-bs disables backing store support on all screens.
-c turns off key-click.
cvolume sets key-click volume (allowable range: 0-100).
-ccclass
sets the visual class for the root window of color
screens. The class numbers are as specified in the X
protocol. Not obeyed by all servers.
-cofilename
sets name of RGB color database.
-dpiresolution
sets the resolution of the screen, in dots per inch.
To be used when the server cannot determine the screen
size from the hardware.
-fvolume
sets beep (bell) volume (allowable range: 0-100).
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-fccursorFont
sets default cursor font.
-fnfont sets the default font.
-fpfontPath
sets the search path for fonts. This path is a comma
separated list of directories which the X server
searches for font databases.
-help prints a usage message.
-I causes all remaining command line arguments to be
ignored.
-ldkilobytes
sets the data space limit of the server to the
specified number of kilobytes. A value of zero makes
the data size as large as possible. The default value
of -1 leaves the data space limit unchanged. This
option is not available in all operating systems.
-lffiles
sets the number-of-open-files limit of the server to
the specified number. A value of zero makes the limit
as large as possible. The default value of -1 leaves
the limit unchanged. This option is not available on
all operating systems.
-lskilobytes
sets the stack space limit of the server to the
specified number of kilobytes. A value of zero makes
the stack size as large as possible. The default
value of -1 leaves the stack space limit unchanged.
This option is not available in all operating systems.
-logo turns on the X Window System logo display in the
screen-saver. There is currently no way to change
this from a client.
nologo turns off the X Window System logo display in the
screen-saver. There is currently no way to change
this from a client.
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-npn turns off the partial network availability.
-pn turns on the partial network availability.
-bpcolor
sets the black pixel for the screen.
-wpcolor
sets the white pixel for the screen.
-configstring
specifies configuration file to be used.
-stdvga specifies "Standard VGA, 640x480 16 color" is the mode
to be used.
-cmapstring
specifies the colormap file to be used. This valid
for only 16 color modes.
-runclassfixed|timeshare|realtime
specifies the class to be used for running the server.
Default is fixed.
-xnetaccesson|off
turns network access checking on or off.
-pminutes
sets screen-saver pattern cycle time in minutes.
-r turns off auto-repeat.
r turns on auto-repeat.
-sminutes
sets screen-saver timeout time in minutes.
-su disables save under support on all screens.
-tnumber
sets pointer acceleration threshold in pixels (i.e.
after how many pixels pointer acceleration should take
effect).
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-toseconds
sets default connection timeout in seconds.
ttyxx ignored, for servers started the ancient way (from
init).
v sets video-off screen-saver preference.
-v sets video-on screen-saver preference.
-wm forces the default backing-store of all windows to be
WhenMapped; a cheap trick way of getting backing-store
to apply to all windows.
You can also have the X server connect to xdm using XDMCP.
Although this is not typically useful as it does not allow xdm
to manage the server process, it can be used to debug XDMCP
implementations, and serves as a sample implementation of the
server side of XDMCP. For more information on this protocol,
see the X Display Manager Control Protocol specification. The
following options control the behavior of XDMCP.
-queryhost-name
Enable XDMCP and send Query packets to the specified
host.
-broadcast
Enable XDMCP and broadcast BroadcastQuery packets to
the network. The first responding display manager
will be chosen for the session.
-indirecthost-name
Enable XDMCP and send IndirectQuery packets to the
specified host.
-portport-num
Use an alternate port number for XDMCP packets. Must
be specified before any -query, -broadcast or
-indirect options.
-once Normally, the server keeps starting sessions, one
after the other. This option makes the server exit
after the first session is over.
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-classdisplay-class
XDMCP has an additional display qualifier used in
resource lookup for display-specific options. This
option sets that value, by default it is "MIT-
Unspecified" (not a very useful value).
-displayIDdisplay-id
Yet another XDMCP specific value, this one allows the
display manager to identify each display so that it
can locate the shared key.
SECURITY
The X server implements a simplistic authorization protocol,
MIT-MAGIC-COOKIE-1 which uses data private to authorized
clients and the server. This is a rather trivial scheme; if
the client passes authorization data which is the same as the
server has, it is allowed access. This scheme is worse than
the host-based access control mechanisms in environments with
unsecure networks as it allows any host to connect, given that
it has discovered the private key. But in many environments,
this level of security is better than the host-based scheme as
it allows access control per-user instead of per-host.
In addition, the server provides support for a DES-based
authorization scheme, XDM-AUTHORIZATION-1, which is more
secure (given a secure key distribution mechanism). This
authorization scheme can be used in conjunction with XDMCP's
authentication scheme (XDM-AUTHENTICATION-1) or in isolation.
The authorization data is passed to the server in a private
file named with the -auth command line option. Each time the
server is about to accept the first connection after a reset
(or when the server is starting), it reads this file. If this
file contains any authorization records, the local host is not
automatically allowed access to the server, and only clients
which send one of the authorization records contained in the
file in the connection setup information will be allowed
access. See the Xau manual page for a description of the
binary format of this file. Maintenance of this file, and
distribution of its contents to remote sites for use there is
left as an exercise for the reader.
The X server also uses a host-based access control list for
deciding whether or not to accept connections from clients on
a particular machine. If no other authorization mechanism is
being used, this list initially consists of the host on which
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the server is running as well as any machines listed in the
file /etc/Xn.hosts, where n is the display number of the
server. Each line of the file should contain an Internet
hostname (e.g. expo.lcs.mit.edu). There should be no leading
or trailing spaces on any lines. For example:
joesworkstation
corporate.company.com
Users can add or remove hosts from this list and enable or
disable access control using the xhost command from the same
machine as the server.
The X protocol intrinsically does not have any notion of
window operation permissions or place any restrictions on what
a client can do; if a program can connect to a display, it has
full run of the screen. Sites that have better authentication
and authorization systems (such as Kerberos) might wish to
make use of the hooks in the libraries and the server to
provide additional security models.
SIGNALS
The X server attaches special meaning to the following
signals:
SIGHUP This signal causes the server to close all existing
connections, free all resources, and restore all
defaults. It is sent by the display manager whenever
the main user's main application (usually an xterm or
window manager) exits to force the server to clean up
and prepare for the next user.
SIGTERM This signal causes the server to exit cleanly.
SIGUSR1 This signal is used quite differently from either of
the above. When the server starts, it checks to see
if it has inherited SIGUSR1 as SIG_IGN instead of the
usual SIG_DFL. In this case, the server sends a
SIGUSR1 to its parent process after it has set up the
various connection schemes. Xdm uses this feature to
recognize when connecting to the server is possible.
FONTS
Fonts are usually stored as individual files in directories.
The X server can obtain fonts from directories and/or from
font servers. The list of directories and font servers the X
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server uses when trying to open a font is controlled by the
font path. Although most sites will choose to have the X
server start up with the appropriate font path (using the -fp
option mentioned above), it can be overridden using the xset
program.
The default font path for the X server contains four
directories:
/usr/X/lib/fonts/misc
This directory contains many miscellaneous bitmap
fonts that are useful on all systems. It contains a
family of fixed-width fonts, a family of fixed-width
fonts from Dale Schumacher, several Kana fonts from
Sony Corporation, two JIS Kanji fonts, two Hangul
fonts from Daewoo Electronics, two Hebrew fonts from
Joseph Friedman, the standard cursor font, two cursor
fonts from Digital Equipment Corporation, and cursor
and glyph fonts from Sun Microsystems. It also has
various font name aliases for the fonts, including
fixed and variable.
/usr/X/lib/fonts/75dpi
This directory contains bitmap fonts contributed by
Adobe Systems, Inc., Digital Equipment Corporation,
Bitstream, Inc., Bigelow and Holmes, and Sun
Microsystems, Inc. for 75 dots per inch displays. An
integrated selection of sizes, styles, and weights are
provided for each family.
/usr/X/lib/fonts/100dpi
This directory contains 100 dots per inch versions of
some of the fonts in the 75dpi directory.
Font databases are created by running the mkfontdir program in
the directory containing the compiled versions of the fonts
(the mkfontdir should be rerun so that the server can find the
new fonts. If mkfontdir is not run, the server will not be
able to find any fonts in the directory.
FILES
/etc/X*.hosts Initial access control list
/usr/X/lib/fonts/misc,/usr/X/lib/fonts/75dpi,/usr/X/lib/fonts/100dpi
Bitmap font directories
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/usr/X/lib/fonts/Speedo Outline font directory
/usr/X/lib/rgb.txt Color database
/tmp/.X11-unix/X* Unix domain socket
SEE ALSO
X(1), bdftopcf(1), mkfontdir(1), fs(1), xauth(1), xdm(1),
xhost(1), xinit(1), xset(1), xsetroot(1), xterm(1), Xibm(1),
XmacII(1), Xmips(1), Xqdss(1), Xqvss(1), Xsun(1), Xtek(1),
X386(1) X Window System Protocol, Definition of the Porting
Layer for the X v11 Sample Server, Strategies for Porting the
X v11 Sample Server, Godzilla's Guide to Porting the X V11
Sample Server
BUGS
The option syntax is inconsistent with itself and xset(1).
The acceleration option should take a numerator and a
denominator like the protocol.
If X dies before its clients, new clients won't be able to
connect until all existing connections have their TCP
TIME_WAIT timers expire.
The color database is missing a large number of colors.
COPYRIGHT
Copyright 1984, 1985, 1986, 1987, 1988, 1989, 1990, 1991
Massachusetts Institute of Technology.
AUTHORS
The sample server was originally written by Susan Angebranndt,
Raymond Drewry, Philip Karlton, and Todd Newman, from Digital
Equipment Corporation, with support from a large cast. It has
since been extensively rewritten by Keith Packard and Bob
Scheifler, from MIT.
Copyright 1994 Novell, Inc. Page 9