Xhp(1) General Commands Manual Xhp(1)
NAME
X - X Window System server
SYNOPSIS
X :displaynumber [-option] ttyname
DESCRIPTION
X is the generic name for the X Window System server. It is started by the dtlogin program which is typically run by init(1M). Alterna-
tively it may be started from the xinit(1) program, which is called by x11start. The displaynumber argument is used by clients in their
DISPLAY environment variables to indicate which server to contact (machines may have several displays attached). This number can be any
number. If no number is specified 0 is used. This number is also used in determining the names of various startup files. The ttyname
argument is passed in by init and isn't used.
The Hewlett-Packard server has support for the following protocols:
TCPIP
The server listens on port 6000+N, where N is the display number.
Local Socket IPC Mechanism
The file name for the socket is "/var/spool/sockets/X11/*" where "*" is the display number.
When the X server starts up, it takes over the display. If you are running on a system whose console is the display, you cannot log into
the console while the X server is running.
OPTIONS
The following options can be given on the command line to the X server.
-a number
sets pointer acceleration (i.e. the ratio of how much is reported to how much the user actually moved the pointer).
-audit level
Sets the audit trail level. The default level is 1, meaning only connection rejections are reported. Level 2 additionally reports
all successful connections and disconnects. Level 4 enables messages from the SECURITY extension, including generation and revoca-
tion of authorizations and violations of the security policy. Level 0 turns off the audit trail. Audit lines are sent as standard
error output.
-auth authorization-file
Specifies a file which contains a collection of authorization records used to authenticate access.
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.
c volume
sets key-click volume (allowable range: 0-100).
-co filename
sets name of RGB color database.
-core causes the server to generate a core dump on fatal errors.
-dpi resolution
sets the resolution of the screen, in dots per inch. To be used when the server cannot determine the screen size from the hard-
ware.
-f volume
sets beep (bell) volume (allowable range: 0-100).
-fc cursorFont
sets default cursor font.
-fn font
sets the default font.
-fp fontPath
sets the search path for fonts. This path is a comma separated list of directories which the server searches for font databases.
-help prints a usage message.
-I causes all remaining command line arguments to be ignored.
-logo turns on the X Window System logo display in the screen-saver. There is currently no way to change this from a client. You also
need to specify -v to enable the logo to appear.
nologo turns off the X Window System logo display in the screen-saver. There is currently no way to change this from a client.
-p minutes
sets screen-saver pattern cycle time in minutes.
-pn allows X server to run even if one or more communications mechanisms fails to initialize.
-pn permits the server to continue running if it fails to establish all of its well-known sockets, but establishes at least one.
-r turns off keyboard auto-repeat.
r turns on keyboard auto-repeat.
-s minutes
sets screen-saver timeout time in minutes.
-sp filename
causes the server to attempt to read and interpret filename as a security policy file with the format described in the SECURITY
FILE FORMAT section below. The file is read at server startup and reread at each server reset. The default file is /etc/X11/Secu-
rityPolicy.
-su disables save under support on all screens.
-t number
sets pointer acceleration threshold in pixels (i.e. after how many pixels pointer acceleration should take effect).
-terminate
causes the server to terminate at server reset, instead of continuing to run.
-to seconds
sets default connection timeout in seconds.
-tst disables all testing extensions (e.g., XTEST, XTestExtension1).
ttyxx ignored, for servers started the ancient way (from init).
-terminage
causes server to terminate when all clients disconnect.
v sets video-on screen-saver preference. A window that changes regularly will be used to save the screen.
-v sets video-off screen-saver preference. The screen will be blanked to save the screen.
-wm forces the default backing-store of all windows to be WhenMapped; a less expensive way of getting backing-store to apply to all
windows.
You can also have the X server connect to dtlogin(1X) using
XDMCP. Although this is not typically useful as it doesn't 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. The following options control the behavior of
XDMCP.
-query host-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 ses-
sion.
-indirect host-name
Enable XDMCP and send IndirectQuery packets to the specified host.
-port port-num
Use an alternate port number for XDMCP packets. Must be specified before any -query, -broadcast or -indirect options. Default port
number is 177.
-class display-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).
-cookie xdm-auth-bits
When testing XDM-AUTHENTICATION-1, a private key is shared between the server and the manager. This option sets the value of that
private data (not that it's very private, being on the command line and all...).
-displayID display-id
Yet another XDMCP specific value, this one allows the display manager to identify each display so that it can locate the shared
key.
XVFB OPTIONS
The X server can be configured to run in virtual frame buffer (Xvfb) mode (see the X server information file
/usr/lib/X11/Xserver/info/screens/hp). Xvfb mode emulates a dumb framebuffer using virtual memory so it can be run on machines with no
display hardware and no physical input devices.
The primary use of this mode was intended to be server testing. The mfb or cfb code for any depth can be exercised with this server with-
out the need for real hardware that supports the desired depths. The X community has found many other novel uses for Xvfb mode, 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.
When run in Xvfb mode, the X server supports the following additional options:
-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 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 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.
SECURITY FILE FORMAT
The syntax of the security policy file is as follows. Notation: "*" means zero or more occurrences of the preceding element, and "+" means
one or more occurrences. To interpret <foo/bar>, ignore the text after the /; it is used to distinguish between instances of <foo> in the
next section.
<policy file> ::= <version line> <other line>*
<version line> ::= <string/v> '
'
<other line > ::= <comment> | <access rule> | <site policy> | <blank line>
<comment> ::= # <not newline>* '
'
<blank line> ::= <space> '
'
<site policy> ::= sitepolicy <string/sp> '
'
<access rule> ::= property <property/ar> <window> <perms> '
'
<property> ::= <string>
<window> ::= any | root | <required property>
<required property> ::= <property/rp> | <property with value>
<property with value> ::= <property/rpv> = <string/rv>
<perms> ::= [ <operation> | <action> | <space> ]*
<operation> ::= r | w | d
<action> ::= a | i | e
<string> ::= <dbl quoted string> | <single quoted string> | <unqouted string>
<dbl quoted string> ::= <space> " <not dqoute>* " <space>
<single quoted string> ::= <space> ' <not squote>* ' <space>
<unquoted string> ::= <space> <not space>+ <space>
<space> ::= [ ' ' | ' ' ]*
Character sets:
<not newline> ::= any character except '
'
<not dqoute> ::= any character except "
<not squote> ::= any character except '
<not space> ::= any character except those in <space>
The semantics associated with the above syntax are as follows.
<version line>, the first line in the file, specifies the file format version. If the server does not recognize the version <string/v>, it
ignores the rest of the file. The version string for the file format described here is "version-1" .
Once past the <version line>, lines that do not match the above syntax are ignored.
<comment> lines are ignored.
<sitepolicy> lines are currently ignored. They are intended to specify the site policies used by the XC-QUERY-SECURITY-1 authorization
method.
<access rule> lines specify how the server should react to untrusted client requests that affect the X Window property named <property/ar>.
The rest of this section describes the interpretation of an <access rule>.
For an <access rule> to apply to a given instance of <property/ar>, <property/ar> must be on a window that is in the set of windows speci-
fied by <window>. If <window> is any, the rule applies to <property/ar> on any window. If <window> is root, the rule applies to <prop-
erty/ar> only on root windows.
If <window> is <required property>, the following apply. If <required property> is a <property/rp>, the rule applies when the window also
has that <property/rp>, regardless of its value. If <required property> is a <property with value>, <property/rpv> must also have the
value specified by <string/rv>. In this case, the property must have type STRING and format 8, and should contain one or more null-termi-
nated strings. If any of the strings match <string/rv>, the rule applies.
The definition of string matching is simple case-sensitive string comparison with one elaboration: the occurence of the character '*' in
<string/rv> is a wildcard meaning "any string." A <string/rv> can contain multiple wildcards anywhere in the string. For example, "x*"
matches strings that begin with x, "*x" matches strings that end with x, "*x*" matches strings containing x, and "x*y*" matches strings
that start with x and subsequently contain y.
There may be multiple <access rule> lines for a given <property/ar>. The rules are tested in the order that they appear in the file. The
first rule that applies is used.
<perms> specify operations that untrusted clients may attempt, and the actions that the server should take in response to those operations.
<operation> can be r (read), w (write), or d (delete). The following table shows how X Protocol property requests map to these operations
in The Open Group server implementation.
GetProperty r, or r and d if delete = True
ChangeProperty w
RotateProperties r and w
DeleteProperty d
ListProperties none, untrusted clients can always list all properties
<action> can be a (allow), i (ignore), or e (error). Allow means execute the request as if it had been issued by a trusted client. Ignore
means treat the request as a no-op. In the case of GetProperty, ignore means return an empty property value if the property exists,
regardless of its actual value. Error means do not execute the request and return a BadAtom error with the atom set to the property name.
Error is the default action for all properties, including those not listed in the security policy file.
An <action> applies to all <operation>s that follow it, until the next <action> is encountered. Thus, irwad means ignore read and write,
allow delete.
GetProperty and RotateProperties may do multiple operations (r and d, or r and w). If different actions apply to the operations, the most
severe action is applied to the whole request; there is no partial request execution. The severity ordering is: allow < ignore < error.
Thus, if the <perms> for a property are ired (ignore read, error delete), and an untrusted client attempts GetProperty on that property
with delete = True, an error is returned, but the property value is not. Similarly, if any of the properties in a RotateProperties do not
allow both read and write, an error is returned without changing any property values.
Here is an example security policy file.
version-1
# Allow reading of application resources, but not writing.
property RESOURCE_MANAGER root ar iw
property SCREEN_RESOURCES root ar iw
# Ignore attempts to use cut buffers. Giving errors causes apps to crash,
# and allowing access may give away too much information.
property CUT_BUFFER0 root irw
property CUT_BUFFER1 root irw
property CUT_BUFFER2 root irw
property CUT_BUFFER3 root irw
property CUT_BUFFER4 root irw
property CUT_BUFFER5 root irw
property CUT_BUFFER6 root irw
property CUT_BUFFER7 root irw
# If you are using Motif, you may want these.
property _MOTIF_DEFAULT_BINDINGS root ar iw
property _MOTIF_DRAG_WINDOW root ar iw
property _MOTIF_DRAG_TARGETS any ar iw
property _MOTIF_DRAG_ATOMS any ar iw
property _MOTIF_DRAG_ATOM_PAIRS any ar iw
# The next two rules let xwininfo -tree work when untrusted.
property WM_NAME any ar
# Allow read of WM_CLASS, but only for windows with WM_NAME.
# This might be more restrictive than necessary, but demonstrates
# the <required property> facility, and is also an attempt to
# say "top level windows only."
property WM_CLASS WM_NAME ar
# These next three let xlsclients work untrusted. Think carefully
# before including these; giving away the client machine name and command
# may be exposing too much.
property WM_STATE WM_NAME ar
property WM_CLIENT_MACHINE WM_NAME ar
property WM_COMMAND WM_NAME ar
# To let untrusted clients use the standard colormaps created by
# xstdcmap, include these lines.
property RGB_DEFAULT_MAP root ar
property RGB_BEST_MAP root ar
property RGB_RED_MAP root ar
property RGB_GREEN_MAP root ar
property RGB_BLUE_MAP root ar
property RGB_GRAY_MAP root ar
# To let untrusted clients use the color management database created
# by xcmsdb, include these lines.
property XDCCC_LINEAR_RGB_CORRECTION root ar
property XDCCC_LINEAR_RGB_MATRICES root ar
property XDCCC_GRAY_SCREENWHITEPOINT root ar
property XDCCC_GRAY_CORRECTION root ar
# To let untrusted clients use the overlay visuals that many vendors
# support, include this line.
property SERVER_OVERLAY_VISUALS root ar
# property names and explicit specification of error conditions
property "property with spaces" 'property with "' aw er ed
# Allow deletion of Woo-Hoo if window also has property OhBoy with value
# ending in "son". Reads and writes will cause an error.
property Woo-Hoo OhBoy = "*son" ad
RUNNING FROM INIT
Though X will usually be run by dtlogin from init, it is possible to run X directly from init. For information about running X from dtlo-
gin, see the dtlogin man page.
To run X directly from init, it is necessary to modify /etc/inittab and /etc/gettydefs. Detailed information on these files may be
obtained from the inittab(4) and gettydefs(4) man pages.
To run X from init on display 0, with a login xterm running on /dev/ttypf, in init state 3, the following line must be added to /etc/init-
tab:
X0:3:respawn:env PATH=/bin:/usr/bin/X11:/usr/bin xinit -L ttyqf -- :0
To run X with a login hpterm, the following should be used instead:
X0:3:respawn:env PATH=/bin:/usr/bin/X11:/usr/bin xinit hpterm =+1+1 -n login -L ttyqf -- :0
In addition, the following line must be added to /etc/gettydefs (this should be a single line):
Xwindow# B9600 HUPCL PARENB CS7 # B9600 SANE PARENB CS7 ISTRIP IXANY TAB3 #X login: #Xwindow
There should not be a getty running against the display whenever X is run from xinit.
GRANTING ACCESS
The sample 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 inferior to 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), but as DES is not generally distributable, the implementation is missing routines to encrypt and decrypt the
authorization data. 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.
The sample server also uses a host-based access control list for deciding whether or not to accept connections from clients on a particular
machine. This list initially consists of the host on which 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:
joessys
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. For example:
% xhost +janessys
janessys being added to access control list
% xhost +
all hosts being allowed (access control disabled)
% xhost -
all hosts being restricted (access control enabled)
% xhost
access control enabled (only the following hosts are allowed)
joessys
janesys
corporate.company.com
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 (dtlogin) whenever the main user's main application 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.
FONTS
Fonts are usually stored as individual files in directories. The list of directories in which the server looks when trying to open a font
is controlled by the font path. Although most sites will choose to have the server start up with the appropriate font path (using the -fp
option mentioned above), it can be overridden using the xset program.
Font databases are created by running the mkfontdir or stmkdirs program in the directory containing the compiled versions of the fonts
(mkfontdir) or font outlines (stmkdirs.) Whenever fonts are added to a directory, mkfontdir or stmkdirs should be rerun so that the server
can find the new fonts. If mkfontdir or stmkdirs is not run, the server will not be able to find any of the new fonts in the directory.
In addition, the X server supports font servers. A font server is a networked program that supplies fonts to X servers and other capable
programs. In order to communicate with a font server, the font servers address must be supplied as part of the X server's font path. A
font server's address is specified as
transport/hostname:port-number
where transport is always tcp, hostname is the hostname of the machine being connected to (no hostname means a local connection) and port-
number is the tcp address that the font server is listening at (typically 7000.)
DIAGNOSTICS
Too numerous to list them all. If run from DE, errors are logged in the file /var/dt/Xerrors,
FILES
/etc/inittab Script for the init process
/etc/gettydefs Speed and terminal settings used by getty
/etc/X*.hosts Initial access control list
/usr/lib/X11/fonts Top level font directory
/etc/X11/rgb.txt Color database
/etc/X11/rgb.pag Color database
/etc/X11/rgb.dir Color database
/var/spool/sockets/X11/* IPC mechanism socket
/var/dt/Xerrors Error log file
/etc/X11/X*devices Input devices used by the server. This file contains many example configurations.
/etc/X11/X*screens Screens used by the server. This file contains many example configurations.
/etc/X11/X*pointerkeys Keyboard pointer device file. This file contains many example configurations.
/etc/X11/XHPkeymaps Key device database used by the X server.
/etc/X11/SecurityPolicy Default Security Policy file used by the X server.
framebuffer-directory/Xvfb_screen<n>
These files are created if the -fbdir option is given. They are the memory mapped file containing screen n's
framebuffer memory, one file per screen. Each 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.
NOTES
The option syntax is inconsistent between itself and xset(1).
The acceleration option should take a numerator and a denominator like the protocol.
The color database is missing a large number of colors. However, there doesn't seem to be a better one available that can generate RGB
values.
COPYRIGHT
Copyright 1996, 1998 The Open Group Copyright 1984, 1985, 1986, 1987, 1988, 1989, 1990, 1991, 1992 Massachusetts Institute of Technology.
Copyright 1992 Hewlett Packard Company.
See X(1) for a full statement of rights and permissions.
SEE ALSO
Xserver(1), Xf86(1), dtlogin(1), bdftopcf(1), fs(1), getty(1M), gettydefs(4), gwindstop(1), hpterm(1), init(1M), inittab(4), mkfontdir(1),
rgb(1), stmkdirs(1), x11start(1), xauth(1) xclock(1), xfd(1), xhost(1), xinit(1), xload(1), xmodmap(1), xrefresh(1), xset(1), xsetroot(1),
xterm(1), xwd(1), xwininfo(1), xwud(1)
Xhp(1)