Provided by: xorg-docs-core_1.7-1_all 
NAME
X - a portable, network-transparent window system
SYNOPSIS
The X Window System is a network transparent window system which runs on a wide range of
computing and graphics machines. It should be relatively straightforward to build the
X.Org Foundation software distribution on most ANSI C and POSIX compliant systems.
Commercial implementations are also available for a wide range of platforms.
The X.Org Foundation requests that the following names be used when referring to this
software:
X
X Window System
X Version 11
X Window System, Version 11
X11
X Window System is a trademark of The Open Group.
DESCRIPTION
X Window System servers run on computers with bitmap displays. The server distributes
user input to and accepts output requests from various client programs through a variety
of different interprocess communication channels. Although the most common case is for
the client programs to be running on the same machine as the server, clients can be run
transparently from other machines (including machines with different architectures and
operating systems) as well.
X supports overlapping hierarchical subwindows and text and graphics operations, on both
monochrome and color displays. For a full explanation of the functions that are
available, see the Xlib - C Language X Interface manual, the X Window System Protocol
specification, the X Toolkit Intrinsics - C Language Interface manual, and various toolkit
documents.
The number of programs that use X is quite large. Programs provided in the core X.Org
Foundation distribution include: a terminal emulator, xterm; a window manager, twm; a
display manager, xdm; a console redirect program, xconsole; a mail interface, xmh; a
bitmap editor, bitmap; resource listing/manipulation tools, appres, editres; access
control programs, xauth, xhost, and iceauth; user preference setting programs, xrdb,
xcmsdb, xset, xsetroot, xstdcmap, and xmodmap; clocks, xclock and oclock; a font
displayer, xfd; utilities for listing information about fonts, windows, and displays,
xlsfonts, xwininfo, xlsclients, xdpyinfo, xlsatoms, and xprop; screen image manipulation
utilities, xwd, xwud, and xmag; a performance measurement utility, x11perf; a font
compiler, bdftopcf; a font server and related utilities, xfs, fsinfo, fslsfonts, fstobdf;
a display server and related utilities, Xserver, rgb, mkfontdir; a clipboard manager,
xclipboard; keyboard description compiler and related utilities, xkbcomp, setxkbmap
xkbprint, xkbbell, xkbevd, xkbvleds, and xkbwatch; a utility to terminate clients, xkill;
a firewall security proxy, xfwp; a proxy manager to control them, proxymngr; a utility to
find proxies, xfindproxy; web browser plug-ins, libxrx.so and libxrxnest.so; an RX MIME-
type helper program, xrx; and a utility to cause part or all of the screen to be redrawn,
xrefresh.
Many other utilities, window managers, games, toolkits, etc. are included as user-
contributed software in the X.Org Foundation distribution, or are available on the
Internet. See your site administrator for details.
STARTING UP
There are two main ways of getting the X server and an initial set of client applications
started. The particular method used depends on what operating system you are running and
whether or not you use other window systems in addition to X.
Display Manager
If you want to always have X running on your display, your site administrator can
set your machine up to use a Display Manager such as xdm, gdm, or kdm. This
program is typically started by the system at boot time and takes care of keeping
the server running and getting users logged in. If you are running one of these
display managers, you will normally see a window on the screen welcoming you to
the system and asking for your login information. Simply type them in as you
would at a normal terminal. If you make a mistake, the display manager will
display an error message and ask you to try again. After you have successfully
logged in, the display manager will start up your X environment. The
documentation for the display manager you use can provide more details.
xinit (run manually from the shell)
Sites that support more than one window system might choose to use the xinit
program for starting X manually. If this is true for your machine, your site
administrator will probably have provided a program named "x11", "startx", or
"xstart" that will do site-specific initialization (such as loading convenient
default resources, running a window manager, displaying a clock, and starting
several terminal emulators) in a nice way. If not, you can build such a script
using the xinit program. This utility simply runs one user-specified program to
start the server, runs another to start up any desired clients, and then waits for
either to finish. Since either or both of the user-specified programs may be a
shell script, this gives substantial flexibility at the expense of a nice
interface. For this reason, xinit is not intended for end users.
DISPLAY NAMES
From the user's perspective, every X server has a display name of the form:
hostname:displaynumber.screennumber
This information is used by the application to determine how it should connect to the
server and which screen it should use by default (on displays with multiple monitors):
hostname
The hostname specifies the name of the machine to which the display is physically
connected. If the hostname is not given, the most efficient way of communicating
to a server on the same machine will be used.
displaynumber
The phrase "display" is usually used to refer to a collection of monitors that
share a common set of input devices (keyboard, mouse, tablet, etc.). Most
workstations tend to only have one display. Larger, multi-user systems, however,
frequently have several displays so that more than one person can be doing
graphics work at once. To avoid confusion, each display on a machine is assigned
a display number (beginning at 0) when the X server for that display is started.
The display number must always be given in a display name.
screennumber
Some displays share their input devices among two or more monitors. These may be
configured as a single logical screen, which allows windows to move across
screens, or as individual screens, each with their own set of windows. If
configured such that each monitor has its own set of windows, each screen is
assigned a screen number (beginning at 0) when the X server for that display is
started. If the screen number is not given, screen 0 will be used.
On POSIX systems, the default display name is stored in your DISPLAY environment variable.
This variable is set automatically by the xterm terminal emulator. However, when you log
into another machine on a network, you may need to set DISPLAY by hand to point to your
display. For example,
% setenv DISPLAY myws:0
$ DISPLAY=myws:0; export DISPLAY
The ssh program can be used to start an X program on a remote machine; it automatically
sets the DISPLAY variable correctly.
Finally, most X programs accept a command line option of -display displayname to
temporarily override the contents of DISPLAY. This is most commonly used to pop windows
on another person's screen or as part of a "remote shell" command to start an xterm
pointing back to your display. For example,
% xeyes -display joesws:0 -geometry 1000x1000+0+0
% rsh big xterm -display myws:0 -ls </dev/null &
X servers listen for connections on a variety of different communications channels
(network byte streams, shared memory, etc.). Since there can be more than one way of
contacting a given server, The hostname part of the display name is used to determine the
type of channel (also called a transport layer) to be used. X servers generally support
the following types of connections:
local
The hostname part of the display name should be the empty string. For example:
:0, :1, and :0.1. The most efficient local transport will be chosen.
TCPIP
The hostname part of the display name should be the server machine's hostname or
IP address. Full Internet names, abbreviated names, IPv4 addresses, and IPv6
addresses are all allowed. For example: x.org:0, expo:0, [::1]:0,
198.112.45.11:0, bigmachine:1, and hydra:0.1.
ACCESS CONTROL
An X server can use several types of access control. Mechanisms provided in Release 7
are:
Host Access Simple host-based access control.
MIT-MAGIC-COOKIE-1 Shared plain-text "cookies".
XDM-AUTHORIZATION-1 Secure DES based private-keys.
SUN-DES-1 Based on Sun's secure rpc system.
Server Interpreted Server-dependent methods of access control
Xdm initializes access control for the server and also places authorization information in
a file accessible to the user. Normally, the list of hosts from which connections are
always accepted should be empty, so that only clients with are explicitly authorized can
connect to the display. When you add entries to the host list (with xhost), the server no
longer performs any authorization on connections from those machines. Be careful with
this.
The file from which Xlib extracts authorization data can be specified with the environment
variable XAUTHORITY, and defaults to the file .Xauthority in the home directory. Xdm uses
$HOME/.Xauthority and will create it or merge in authorization records if it already
exists when a user logs in.
If you use several machines and share a common home directory across all of the machines
by means of a network file system, you never really have to worry about authorization
files, the system should work correctly by default. Otherwise, as the authorization files
are machine-independent, you can simply copy the files to share them. To manage
authorization files, use xauth. This program allows you to extract records and insert
them into other files. Using this, you can send authorization to remote machines when you
login, if the remote machine does not share a common home directory with your local
machine. Note that authorization information transmitted ``in the clear'' through a
network file system or using ftp or rcp can be ``stolen'' by a network eavesdropper, and
as such may enable unauthorized access. In many environments, this level of security is
not a concern, but if it is, you need to know the exact semantics of the particular
authorization data to know if this is actually a problem.
For more information on access control, see the Xsecurity(7) manual page.
GEOMETRY SPECIFICATIONS
One of the advantages of using window systems instead of hardwired terminals is that
applications don't have to be restricted to a particular size or location on the screen.
Although the layout of windows on a display is controlled by the window manager that the
user is running (described below), most X programs accept a command line argument of the
form -geometry WIDTHxHEIGHT+XOFF+YOFF (where WIDTH, HEIGHT, XOFF, and YOFF are numbers)
for specifying a preferred size and location for this application's main window.
The WIDTH and HEIGHT parts of the geometry specification are usually measured in either
pixels or characters, depending on the application. The XOFF and YOFF parts are measured
in pixels and are used to specify the distance of the window from the left or right and
top and bottom edges of the screen, respectively. Both types of offsets are measured from
the indicated edge of the screen to the corresponding edge of the window. The X offset
may be specified in the following ways:
+XOFF The left edge of the window is to be placed XOFF pixels in from the left edge of
the screen (i.e., the X coordinate of the window's origin will be XOFF). XOFF may
be negative, in which case the window's left edge will be off the screen.
-XOFF The right edge of the window is to be placed XOFF pixels in from the right edge of
the screen. XOFF may be negative, in which case the window's right edge will be
off the screen.
The Y offset has similar meanings:
+YOFF The top edge of the window is to be YOFF pixels below the top edge of the screen
(i.e., the Y coordinate of the window's origin will be YOFF). YOFF may be
negative, in which case the window's top edge will be off the screen.
-YOFF The bottom edge of the window is to be YOFF pixels above the bottom edge of the
screen. YOFF may be negative, in which case the window's bottom edge will be off
the screen.
Offsets must be given as pairs; in other words, in order to specify either XOFF or YOFF
both must be present. Windows can be placed in the four corners of the screen using the
following specifications:
+0+0 upper left hand corner.
-0+0 upper right hand corner.
-0-0 lower right hand corner.
+0-0 lower left hand corner.
In the following examples, a terminal emulator is placed in roughly the center of the
screen and a load average monitor, mailbox, and clock are placed in the upper right hand
corner:
xterm -fn 6x10 -geometry 80x24+30+200 &
xclock -geometry 48x48-0+0 &
xload -geometry 48x48-96+0 &
xbiff -geometry 48x48-48+0 &
WINDOW MANAGERS
The layout of windows on the screen is controlled by special programs called window
managers. Although many window managers will honor geometry specifications as given,
others may choose to ignore them (requiring the user to explicitly draw the window's
region on the screen with the pointer, for example).
Since window managers are regular (albeit complex) client programs, a variety of different
user interfaces can be built. The X.Org Foundation distribution comes with a window
manager named twm which supports overlapping windows, popup menus, point-and-click or
click-to-type input models, title bars, nice icons (and an icon manager for those who
don't like separate icon windows).
See the user-contributed software in the X.Org Foundation distribution for other popular
window managers.
FONT NAMES
Collections of characters for displaying text and symbols in X are known as fonts. A font
typically contains images that share a common appearance and look nice together (for
example, a single size, boldness, slant, and character set). Similarly, collections of
fonts that are based on a common type face (the variations are usually called roman, bold,
italic, bold italic, oblique, and bold oblique) are called families.
Fonts come in various sizes. The X server supports scalable fonts, meaning it is possible
to create a font of arbitrary size from a single source for the font. The server supports
scaling from outline fonts and bitmap fonts. Scaling from outline fonts usually produces
significantly better results than scaling from bitmap fonts.
An X server can obtain fonts from individual files stored in directories in the file
system, or from one or more font servers, or from a mixtures of directories and font
servers. The list of places the server looks when trying to find a font is controlled by
its font path. Although most installations will choose to have the server start up with
all of the commonly used font directories in the font path, the font path can be changed
at any time with the xset program. However, it is important to remember that the
directory names are on the server's machine, not on the application's.
Bitmap font files are usually created by compiling a textual font description into binary
form, using bdftopcf. Font databases are created by running the mkfontdir program in the
directory containing the source or compiled versions of the fonts. Whenever fonts are
added to a directory, mkfontdir should be rerun so that the server can find the new fonts.
To make the server reread the font database, reset the font path with the xset program.
For example, to add a font to a private directory, the following commands could be used:
% cp newfont.pcf ~/myfonts
% mkfontdir ~/myfonts
% xset fp rehash
The xfontsel and xlsfonts programs can be used to browse through the fonts available on a
server. Font names tend to be fairly long as they contain all of the information needed
to uniquely identify individual fonts. However, the X server supports wildcarding of font
names, so the full specification
-adobe-courier-medium-r-normal--10-100-75-75-m-60-iso8859-1
might be abbreviated as:
-*-courier-medium-r-normal--*-100-*-*-*-*-iso8859-1
Because the shell also has special meanings for * and ?, wildcarded font names should be
quoted:
% xlsfonts -fn '-*-courier-medium-r-normal--*-100-*-*-*-*-*-*'
The xlsfonts program can be used to list all of the fonts that match a given pattern.
With no arguments, it lists all available fonts. This will usually list the same font at
many different sizes. To see just the base scalable font names, try using one of the
following patterns:
-*-*-*-*-*-*-0-0-0-0-*-0-*-*
-*-*-*-*-*-*-0-0-75-75-*-0-*-*
-*-*-*-*-*-*-0-0-100-100-*-0-*-*
To convert one of the resulting names into a font at a specific size, replace one of the
first two zeros with a nonzero value. The field containing the first zero is for the
pixel size; replace it with a specific height in pixels to name a font at that size.
Alternatively, the field containing the second zero is for the point size; replace it with
a specific size in decipoints (there are 722.7 decipoints to the inch) to name a font at
that size. The last zero is an average width field, measured in tenths of pixels; some
servers will anamorphically scale if this value is specified.
FONT SERVER NAMES
One of the following forms can be used to name a font server that accepts TCP connections:
tcp/hostname:port
tcp/hostname:port/cataloguelist
The hostname specifies the name (or decimal numeric address) of the machine on which the
font server is running. The port is the decimal TCP port on which the font server is
listening for connections. The cataloguelist specifies a list of catalogue names, with
'+' as a separator.
Examples: tcp/x.org:7100, tcp/198.112.45.11:7100/all.
COLOR NAMES
Most applications provide ways of tailoring (usually through resources or command line
arguments) the colors of various elements in the text and graphics they display. A color
can be specified either by an abstract color name, or by a numerical color specification.
The numerical specification can identify a color in either device-dependent (RGB) or
device-independent terms. Color strings are case-insensitive.
X supports the use of abstract color names, for example, "red", "blue". A value for this
abstract name is obtained by searching one or more color name databases. Xlib first
searches zero or more client-side databases; the number, location, and content of these
databases is implementation dependent. If the name is not found, the color is looked up
in the X server's database. The text form of this database is commonly stored in the file
usr/share/X11/rgb.txt.
A numerical color specification consists of a color space name and a set of values in the
following syntax:
<color_space_name>:<value>/.../<value>
An RGB Device specification is identified by the prefix "rgb:" and has the following
syntax:
rgb:<red>/<green>/<blue>
<red>, <green>, <blue> := h | hh | hhh | hhhh
h := single hexadecimal digits
Note that h indicates the value scaled in 4 bits, hh the value scaled in 8 bits, hhh the
value scaled in 12 bits, and hhhh the value scaled in 16 bits, respectively. These values
are passed directly to the X server, and are assumed to be gamma corrected.
The eight primary colors can be represented as:
black rgb:0/0/0
red rgb:ffff/0/0
green rgb:0/ffff/0
blue rgb:0/0/ffff
yellow rgb:ffff/ffff/0
magenta rgb:ffff/0/ffff
cyan rgb:0/ffff/ffff
white rgb:ffff/ffff/ffff
For backward compatibility, an older syntax for RGB Device is supported, but its continued
use is not encouraged. The syntax is an initial sharp sign character followed by a
numeric specification, in one of the following formats:
#RGB (4 bits each)
#RRGGBB (8 bits each)
#RRRGGGBBB (12 bits each)
#RRRRGGGGBBBB (16 bits each)
The R, G, and B represent single hexadecimal digits. When fewer than 16 bits each are
specified, they represent the most-significant bits of the value (unlike the "rgb:"
syntax, in which values are scaled). For example, #3a7 is the same as #3000a0007000.
An RGB intensity specification is identified by the prefix "rgbi:" and has the following
syntax:
rgbi:<red>/<green>/<blue>
The red, green, and blue are floating point values between 0.0 and 1.0, inclusive. They
represent linear intensity values, with 1.0 indicating full intensity, 0.5 half intensity,
and so on. These values will be gamma corrected by Xlib before being sent to the X
server. The input format for these values is an optional sign, a string of numbers
possibly containing a decimal point, and an optional exponent field containing an E or e
followed by a possibly signed integer string.
The standard device-independent string specifications have the following syntax:
CIEXYZ:<X>/<Y>/<Z> (none, 1, none)
CIEuvY:<u>/<v>/<Y> (~.6, ~.6, 1)
CIExyY:<x>/<y>/<Y> (~.75, ~.85, 1)
CIELab:<L>/<a>/<b> (100, none, none)
CIELuv:<L>/<u>/<v> (100, none, none)
TekHVC:<H>/<V>/<C> (360, 100, 100)
All of the values (C, H, V, X, Y, Z, a, b, u, v, y, x) are floating point values. Some of
the values are constrained to be between zero and some upper bound; the upper bounds are
given in parentheses above. The syntax for these values is an optional '+' or '-' sign, a
string of digits possibly containing a decimal point, and an optional exponent field
consisting of an 'E' or 'e' followed by an optional '+' or '-' followed by a string of
digits.
For more information on device independent color, see the Xlib reference manual.
KEYBOARDS
The X keyboard model is broken into two layers: server-specific codes (called keycodes)
which represent the physical keys, and server-independent symbols (called keysyms) which
represent the letters or words that appear on the keys. Two tables are kept in the server
for converting keycodes to keysyms:
modifier list
Some keys (such as Shift, Control, and Caps Lock) are known as modifier and are
used to select different symbols that are attached to a single key (such as Shift-
a generates a capital A, and Control-l generates a control character ^L). The
server keeps a list of keycodes corresponding to the various modifier keys.
Whenever a key is pressed or released, the server generates an event that contains
the keycode of the indicated key as well as a mask that specifies which of the
modifier keys are currently pressed. Most servers set up this list to initially
contain the various shift, control, and shift lock keys on the keyboard.
keymap table
Applications translate event keycodes and modifier masks into keysyms using a
keysym table which contains one row for each keycode and one column for various
modifier states. This table is initialized by the server to correspond to normal
typewriter conventions. The exact semantics of how the table is interpreted to
produce keysyms depends on the particular program, libraries, and language input
method used, but the following conventions for the first four keysyms in each row
are generally adhered to:
The first four elements of the list are split into two groups of keysyms. Group 1
contains the first and second keysyms; Group 2 contains the third and fourth keysyms.
Within each group, if the first element is alphabetic and the the second element is the
special keysym NoSymbol, then the group is treated as equivalent to a group in which the
first element is the lowercase letter and the second element is the uppercase letter.
Switching between groups is controlled by the keysym named MODE SWITCH, by attaching that
keysym to some key and attaching that key to any one of the modifiers Mod1 through Mod5.
This modifier is called the ``group modifier.'' Group 1 is used when the group modifier
is off, and Group 2 is used when the group modifier is on.
Within a group, the modifier state determines which keysym to use. The first keysym is
used when the Shift and Lock modifiers are off. The second keysym is used when the Shift
modifier is on, when the Lock modifier is on and the second keysym is uppercase
alphabetic, or when the Lock modifier is on and is interpreted as ShiftLock. Otherwise,
when the Lock modifier is on and is interpreted as CapsLock, the state of the Shift
modifier is applied first to select a keysym; but if that keysym is lowercase alphabetic,
then the corresponding uppercase keysym is used instead.
OPTIONS
Most X programs attempt to use the same names for command line options and arguments. All
applications written with the X Toolkit Intrinsics automatically accept the following
options:
-display display
This option specifies the name of the X server to use.
-geometry geometry
This option specifies the initial size and location of the window.
-bg color, -background color
Either option specifies the color to use for the window background.
-bd color, -bordercolor color
Either option specifies the color to use for the window border.
-bw number, -borderwidth number
Either option specifies the width in pixels of the window border.
-fg color, -foreground color
Either option specifies the color to use for text or graphics.
-fn font, -font font
Either option specifies the font to use for displaying text.
-iconic
This option indicates that the user would prefer that the application's windows
initially not be visible as if the windows had be immediately iconified by the
user. Window managers may choose not to honor the application's request.
-name
This option specifies the name under which resources for the application should be
found. This option is useful in shell aliases to distinguish between invocations
of an application, without resorting to creating links to alter the executable
file name.
-rv, -reverse
Either option indicates that the program should simulate reverse video if
possible, often by swapping the foreground and background colors. Not all
programs honor this or implement it correctly. It is usually only used on
monochrome displays.
+rv
This option indicates that the program should not simulate reverse video. This is
used to override any defaults since reverse video doesn't always work properly.
-selectionTimeout
This option specifies the timeout in milliseconds within which two communicating
applications must respond to one another for a selection request.
-synchronous
This option indicates that requests to the X server should be sent synchronously,
instead of asynchronously. Since Xlib normally buffers requests to the server,
errors do not necessarily get reported immediately after they occur. This option
turns off the buffering so that the application can be debugged. It should never
be used with a working program.
-title string
This option specifies the title to be used for this window. This information is
sometimes used by a window manager to provide some sort of header identifying the
window.
-xnllanguage language[_territory][.codeset]
This option specifies the language, territory, and codeset for use in resolving
resource and other filenames.
-xrm resourcestring
This option specifies a resource name and value to override any defaults. It is
also very useful for setting resources that don't have explicit command line
arguments.
RESOURCES
To make the tailoring of applications to personal preferences easier, X provides a
mechanism for storing default values for program resources (e.g. background color, window
title, etc.) that is used by programs that use toolkits based on the X Toolkit Intrinsics
library libXt. (Programs using the common Gtk+ and Qt toolkits use other configuration
mechanisms.) Resources are specified as strings that are read in from various places when
an application is run. Program components are named in a hierarchical fashion, with each
node in the hierarchy identified by a class and an instance name. At the top level is the
class and instance name of the application itself. By convention, the class name of the
application is the same as the program name, but with the first letter capitalized (e.g.
Bitmap or Emacs) although some programs that begin with the letter ``x'' also capitalize
the second letter for historical reasons.
The precise syntax for resources is:
ResourceLine = Comment | IncludeFile | ResourceSpec | <empty line>
Comment = "!" {<any character except null or newline>}
IncludeFile = "#" WhiteSpace "include" WhiteSpace FileName WhiteSpace
FileName = <valid filename for operating system>
ResourceSpec = WhiteSpace ResourceName WhiteSpace ":" WhiteSpace Value
ResourceName = [Binding] {Component Binding} ComponentName
Binding = "." | "*"
WhiteSpace = {<space> | <horizontal tab>}
Component = "?" | ComponentName
ComponentName = NameChar {NameChar}
NameChar = "a"-"z" | "A"-"Z" | "0"-"9" | "_" | "-"
Value = {<any character except null or unescaped newline>}
Elements separated by vertical bar (|) are alternatives. Curly braces ({...}) indicate
zero or more repetitions of the enclosed elements. Square brackets ([...]) indicate that
the enclosed element is optional. Quotes ("...") are used around literal characters.
IncludeFile lines are interpreted by replacing the line with the contents of the specified
file. The word "include" must be in lowercase. The filename is interpreted relative to
the directory of the file in which the line occurs (for example, if the filename contains
no directory or contains a relative directory specification).
If a ResourceName contains a contiguous sequence of two or more Binding characters, the
sequence will be replaced with single "." character if the sequence contains only "."
characters, otherwise the sequence will be replaced with a single "*" character.
A resource database never contains more than one entry for a given ResourceName. If a
resource file contains multiple lines with the same ResourceName, the last line in the
file is used.
Any whitespace character before or after the name or colon in a ResourceSpec are ignored.
To allow a Value to begin with whitespace, the two-character sequence ``\space''
(backslash followed by space) is recognized and replaced by a space character, and the
two-character sequence ``\tab'' (backslash followed by horizontal tab) is recognized and
replaced by a horizontal tab character. To allow a Value to contain embedded newline
characters, the two-character sequence ``\n'' is recognized and replaced by a newline
character. To allow a Value to be broken across multiple lines in a text file, the two-
character sequence ``\newline'' (backslash followed by newline) is recognized and removed
from the value. To allow a Value to contain arbitrary character codes, the four-character
sequence ``\nnn'', where each n is a digit character in the range of ``0''-``7'', is
recognized and replaced with a single byte that contains the octal value specified by the
sequence. Finally, the two-character sequence ``\\'' is recognized and replaced with a
single backslash.
When an application looks for the value of a resource, it specifies a complete path in the
hierarchy, with both class and instance names. However, resource values are usually given
with only partially specified names and classes, using pattern matching constructs. An
asterisk (*) is a loose binding and is used to represent any number of intervening
components, including none. A period (.) is a tight binding and is used to separate
immediately adjacent components. A question mark (?) is used to match any single
component name or class. A database entry cannot end in a loose binding; the final
component (which cannot be "?") must be specified. The lookup algorithm searches the
resource database for the entry that most closely matches (is most specific for) the full
name and class being queried. When more than one database entry matches the full name and
class, precedence rules are used to select just one.
The full name and class are scanned from left to right (from highest level in the
hierarchy to lowest), one component at a time. At each level, the corresponding component
and/or binding of each matching entry is determined, and these matching components and
bindings are compared according to precedence rules. Each of the rules is applied at each
level, before moving to the next level, until a rule selects a single entry over all
others. The rules (in order of precedence) are:
1. An entry that contains a matching component (whether name, class, or "?") takes
precedence over entries that elide the level (that is, entries that match the level
in a loose binding).
2. An entry with a matching name takes precedence over both entries with a matching
class and entries that match using "?". An entry with a matching class takes
precedence over entries that match using "?".
3. An entry preceded by a tight binding takes precedence over entries preceded by a
loose binding.
Programs based on the X Toolkit Intrinsics obtain resources from the following sources
(other programs usually support some subset of these sources):
RESOURCE_MANAGER root window property
Any global resources that should be available to clients on all machines should be
stored in the RESOURCE_MANAGER property on the root window of the first screen
using the xrdb program. This is frequently taken care of when the user starts up
X through the display manager or xinit.
SCREEN_RESOURCES root window property
Any resources specific to a given screen (e.g. colors) that should be available to
clients on all machines should be stored in the SCREEN_RESOURCES property on the
root window of that screen. The xrdb program will sort resources automatically
and place them in RESOURCE_MANAGER or SCREEN_RESOURCES, as appropriate.
application-specific files
Directories named by the environment variable XUSERFILESEARCHPATH or the
environment variable XAPPLRESDIR (which names a single directory and should end
with a '/' on POSIX systems), plus directories in a standard place (usually under
/usr/share/X11/, but this can be overridden with the XFILESEARCHPATH environment
variable) are searched for for application-specific resources. For example,
application default resources are usually kept in /usr/share/X11/app-defaults/.
See the X Toolkit Intrinsics - C Language Interface manual for details.
XENVIRONMENT
Any user- and machine-specific resources may be specified by setting the
XENVIRONMENT environment variable to the name of a resource file to be loaded by
all applications. If this variable is not defined, a file named
$HOME/.Xdefaults-hostname is looked for instead, where hostname is the name of the
host where the application is executing.
-xrm resourcestring
Resources can also be specified from the command line. The resourcestring is a
single resource name and value as shown above. Note that if the string contains
characters interpreted by the shell (e.g., asterisk), they must be quoted. Any
number of -xrm arguments may be given on the command line.
Program resources are organized into groups called classes, so that collections of
individual resources (each of which are called instances) can be set all at once. By
convention, the instance name of a resource begins with a lowercase letter and class name
with an upper case letter. Multiple word resources are concatenated with the first letter
of the succeeding words capitalized. Applications written with the X Toolkit Intrinsics
will have at least the following resources:
background (class Background)
This resource specifies the color to use for the window background.
borderWidth (class BorderWidth)
This resource specifies the width in pixels of the window border.
borderColor (class BorderColor)
This resource specifies the color to use for the window border.
Most applications using the X Toolkit Intrinsics also have the resource foreground (class
Foreground), specifying the color to use for text and graphics within the window.
By combining class and instance specifications, application preferences can be set quickly
and easily. Users of color displays will frequently want to set Background and Foreground
classes to particular defaults. Specific color instances such as text cursors can then be
overridden without having to define all of the related resources. For example,
bitmap*Dashed: off
XTerm*cursorColor: gold
XTerm*multiScroll: on
XTerm*jumpScroll: on
XTerm*reverseWrap: on
XTerm*curses: on
XTerm*Font: 6x10
XTerm*scrollBar: on
XTerm*scrollbar*thickness: 5
XTerm*multiClickTime: 500
XTerm*charClass: 33:48,37:48,45-47:48,64:48
XTerm*cutNewline: off
XTerm*cutToBeginningOfLine: off
XTerm*titeInhibit: on
XTerm*ttyModes: intr ^c erase ^? kill ^u
XLoad*Background: gold
XLoad*Foreground: red
XLoad*highlight: black
XLoad*borderWidth: 0
emacs*Geometry: 80x65-0-0
emacs*Background: rgb:5b/76/86
emacs*Foreground: white
emacs*Cursor: white
emacs*BorderColor: white
emacs*Font: 6x10
xmag*geometry: -0-0
xmag*borderColor: white
If these resources were stored in a file called .Xresources in your home directory, they
could be added to any existing resources in the server with the following command:
% xrdb -merge $HOME/.Xresources
This is frequently how user-friendly startup scripts merge user-specific defaults into any
site-wide defaults. All sites are encouraged to set up convenient ways of automatically
loading resources. See the Xlib manual section Resource Manager Functions for more
information.
ENVIRONMENT
DISPLAY
This is the only mandatory environment variable. It must point to an X server. See
section "Display Names" above.
XAUTHORITY
This must point to a file that contains authorization data. The default is
$HOME/.Xauthority. See Xsecurity(7), xauth(1), xdm(1), Xau(3).
ICEAUTHORITY
This must point to a file that contains authorization data. The default is
$HOME/.ICEauthority.
LC_ALL, LC_CTYPE, LANG
The first non-empty value among these three determines the current locale's facet
for character handling, and in particular the default text encoding. See locale(7),
setlocale(3), locale(1).
XMODIFIERS
This variable can be set to contain additional information important for the
current locale setting. Typically set to @im=<input-method> to enable a particular
input method. See XSetLocaleModifiers(3).
XLOCALEDIR
This must point to a directory containing the locale.alias file and Compose and
XLC_LOCALE file hierarchies for all locales. The default value is
/usr/share/X11/locale.
XENVIRONMENT
This must point to a file containing X resources. The default is
$HOME/.Xdefaults-<hostname>. Unlike $HOME/.Xresources, it is consulted each time an
X application starts.
XFILESEARCHPATH
This must contain a colon separated list of path templates, where libXt will search
for resource files. The default value consists of
/usr/etc/X11/%L/%T/%N%C%S:\
/usr/etc/X11/%l/%T/%N%C%S:\
/usr/etc/X11/%T/%N%C%S:\
/usr/etc/X11/%L/%T/%N%S:\
/usr/etc/X11/%l/%T/%N%S:\
/usr/etc/X11/%T/%N%S:\
/usr/share/X11/%L/%T/%N%C%S:\
/usr/share/X11/%l/%T/%N%C%S:\
/usr/share/X11/%T/%N%C%S:\
/usr/share/X11/%L/%T/%N%S:\
/usr/share/X11/%l/%T/%N%S:\
/usr/share/X11/%T/%N%S:\
/usr/lib/X11/%L/%T/%N%C%S:\
/usr/lib/X11/%l/%T/%N%C%S:\
/usr/lib/X11/%T/%N%C%S:\
/usr/lib/X11/%L/%T/%N%S:\
/usr/lib/X11/%l/%T/%N%S:\
/usr/lib/X11/%T/%N%S
A path template is transformed to a pathname by substituting:
%D => the implementation-specific default path
%N => name (basename) being searched for
%T => type (dirname) being searched for
%S => suffix being searched for
%C => value of the resource "customization"
(class "Customization")
%L => the locale name
%l => the locale's language (part before '_')
%t => the locale's territory (part after '_` but before '.')
%c => the locale's encoding (part after '.')
XUSERFILESEARCHPATH
This must contain a colon separated list of path templates, where libXt will search
for user dependent resource files. The default value is:
$XAPPLRESDIR/%L/%N%C:\
$XAPPLRESDIR/%l/%N%C:\
$XAPPLRESDIR/%N%C:\
$HOME/%N%C:\
$XAPPLRESDIR/%L/%N:\
$XAPPLRESDIR/%l/%N:\
$XAPPLRESDIR/%N:\
$HOME/%N
$XAPPLRESDIR defaults to $HOME, see below.
A path template is transformed to a pathname by substituting:
%D => the implementation-specific default path
%N => name (basename) being searched for
%T => type (dirname) being searched for
%S => suffix being searched for
%C => value of the resource "customization"
(class "Customization")
%L => the locale name
%l => the locale's language (part before '_')
%t => the locale's territory (part after '_` but before '.')
%c => the locale's encoding (part after '.')
XAPPLRESDIR
This must point to a base directory where the user stores his application dependent
resource files. The default value is $HOME. Only used if XUSERFILESEARCHPATH is not
set.
XKEYSYMDB
This must point to a file containing nonstandard keysym definitions. The default
value is /usr/share/X11/XKeysymDB.
XCMSDB This must point to a color name database file. The default value is
/usr/lib/X11/Xcms.txt.
RESOURCE_NAME
This serves as main identifier for resources belonging to the program being
executed. It defaults to the basename of pathname of the program.
SESSION_MANAGER
Denotes the session manager to which the application should connect. See xsm(1),
rstart(1).
XF86BIGFONT_DISABLE
Setting this variable to a non-empty value disables the XFree86-Bigfont extension.
This extension is a mechanism to reduce the memory consumption of big fonts by use
of shared memory.
XKB_FORCE
XKB_DISABLE
XKB_DEBUG
_XKB_CHARSET
_XKB_LOCALE_CHARSETS
_XKB_OPTIONS_ENABLE
_XKB_LATIN1_LOOKUP
_XKB_CONSUME_LOOKUP_MODS
_XKB_CONSUME_SHIFT_AND_LOCK
_XKB_IGNORE_NEW_KEYBOARDS
_XKB_CONTROL_FALLBACK
_XKB_COMP_LED _XKB_COMP_FAIL_BEEP
These variables influence the X Keyboard Extension.
EXAMPLES
The following is a collection of sample command lines for some of the more frequently used
commands. For more information on a particular command, please refer to that command's
manual page.
% xrdb $HOME/.Xresources
% xmodmap -e "keysym BackSpace = Delete"
% mkfontdir /usr/local/lib/X11/otherfonts
% xset fp+ /usr/local/lib/X11/otherfonts
% xmodmap $HOME/.keymap.km
% xsetroot -solid 'rgbi:.8/.8/.8'
% xset b 100 400 c 50 s 1800 r on
% xset q
% twm
% xmag
% xclock -geometry 48x48-0+0 -bg blue -fg white
% xeyes -geometry 48x48-48+0
% xbiff -update 20
% xlsfonts '*helvetica*'
% xwininfo -root
% xdpyinfo -display joesworkstation:0
% xhost -joesworkstation
% xrefresh
% xwd | xwud
% bitmap companylogo.bm 32x32
% xcalc -bg blue -fg magenta
% xterm -geometry 80x66-0-0 -name myxterm $*
DIAGNOSTICS
A wide variety of error messages are generated from various programs. The default error
handler in Xlib (also used by many toolkits) uses standard resources to construct
diagnostic messages when errors occur. The defaults for these messages are usually stored
in usr/share/X11/XErrorDB. If this file is not present, error messages will be rather
terse and cryptic.
When the X Toolkit Intrinsics encounter errors converting resource strings to the
appropriate internal format, no error messages are usually printed. This is convenient
when it is desirable to have one set of resources across a variety of displays (e.g. color
vs. monochrome, lots of fonts vs. very few, etc.), although it can pose problems for
trying to determine why an application might be failing. This behavior can be overridden
by the setting the StringConversionWarnings resource.
To force the X Toolkit Intrinsics to always print string conversion error messages, the
following resource should be placed in the file that gets loaded onto the RESOURCE_MANAGER
property using the xrdb program (frequently called .Xresources or .Xres in the user's home
directory):
*StringConversionWarnings: on
To have conversion messages printed for just a particular application, the appropriate
instance name can be placed before the asterisk:
xterm*StringConversionWarnings: on
SEE ALSO
XOrgFoundation(7), XStandards(7), Xsecurity(7), appres(1), bdftopcf(1), bitmap(1),
editres(1), fsinfo(1), fslsfonts(1), fstobdf(1), iceauth(1), imake(1), makedepend(1),
mkfontdir(1), oclock(1), proxymngr(1), rgb(1), resize(1), rstart(1), smproxy(1), twm(1),
x11perf(1), x11perfcomp(1), xauth(1), xclipboard(1), xclock(1), xcmsdb(1), xconsole(1),
xdm(1), xdpyinfo(1), xfd(1), xfindproxy(1), xfs(1), xfwp(1), xhost(1), xinit(1),
xkbbell(1), xkbcomp(1), xkbevd(1), xkbprint(1), xkbvleds(1), xkbwatch(1), xkill(1),
xlogo(1), xlsatoms(1), xlsclients(1), xlsfonts(1), xmag(1), xmh(1), xmodmap(1), xprop(1),
xrdb(1), xrefresh(1), xrx(1), xset(1), xsetroot(1), xsm(1), xstdcmap(1), xterm(1), xwd(1),
xwininfo(1), xwud(1). Xserver(1), Xorg(1), Xdmx(1), Xephyr(1), Xnest(1), Xquartz(1),
Xvfb(1), Xvnc(1), XWin(1). Xlib - C Language X Interface, and X Toolkit Intrinsics - C
Language Interface
TRADEMARKS
X Window System is a trademark of The Open Group.
AUTHORS
A cast of thousands, literally. Releases 6.7 and later are brought to you by the X.Org
Foundation. The names of all people who made it a reality will be found in the individual
documents and source files.
Releases 6.6 and 6.5 were done by The X.Org Group. Release 6.4 was done by The X Project
Team. The Release 6.3 distribution was from The X Consortium, Inc. The staff members at
the X Consortium responsible for that release were: Donna Converse (emeritus), Stephen
Gildea (emeritus), Kaleb Keithley, Matt Landau (emeritus), Ralph Mor (emeritus), Janet
O'Halloran, Bob Scheifler, Ralph Swick, Dave Wiggins (emeritus), and Reed Augliere.
The X Window System standard was originally developed at the Laboratory for Computer
Science at the Massachusetts Institute of Technology, and all rights thereto were assigned
to the X Consortium on January 1, 1994. X Consortium, Inc. closed its doors on December
31, 1996. All rights to the X Window System have been assigned to The Open Group.