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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 Window System software distribution on most ANSI C and
POSIX compliant systems. Commercial implementations are
also available for a wide range of platforms.
The Open Group 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 Window System 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 xmod-
map; clocks, xclock and oclock; a font displayer, (xfd;
utilities for listing information about fonts, windows, and
displays, xlsfonts, xwininfo, xlsclients, xdpyinfo, xlsa-
toms, and xprop; screen image manipulation utilities, xwd,
xwud, and xmag; a performance measurement utility, x11perf;
a font compiler, bdftopcf; a font server and related utili-
ties, xfs, fsinfo, fslsfonts, fstobdf; an X Image Extension
exerciser, xieperf; a display server and related utilities,
Xserver, rgb, mkfontdir; remote execution utilities, rstart
and xon; a clipboard manager, xclipboard; keyboard descrip-
tion compiler and related utilities, xkbcomp, xkbprint,
xkbbell, xkbevd, xkbvleds, and xkbwatch; a utility to ter-
minate clients, xkill; an optimized X protocol proxy,
lbxproxy; a firewall security proxy, xfwp; a proxy manager
to control them, proxymngr; a utility to find proxies,
xfindproxy; Netscape Navigator 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 Window
System distribution, or are available using anonymous ftp on
the Internet. See your site administrator for details.
STARTING UP
There are two main ways of getting the X server and an ini-
tial 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.
xdm (the X Display Manager)
If you want to always have X running on your
display, your site administrator can set your
machine up to use the X Display Manager xdm. 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
xdm, you will see a window on the screen welcoming
you to the system and asking for your username and
password. Simply type them in as you would at a
normal terminal, pressing the Return key after each.
If you make a mistake, xdm will display an error
message and ask you to try again. After you have
successfully logged in, xdm will start up your X
environment. By default, if you have an executable
file named .xsession in your home directory, xdm
will treat it as a program (or shell script) to run
to start up your initial clients (such as terminal
emulators, clocks, a window manager, user settings
for things like the background, the speed of the
pointer, etc.). Your site administrator can provide
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 manu-
ally. 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 con-
venient 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 rea-
son, 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
collection of monitors that share a common keyboard
and pointer (mouse, tablet, etc.). Most worksta-
tions tend to only have one keyboard, and therefore,
only one display. Larger, multi-user systems, how-
ever, 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 a single keyboard and pointer
among two or more monitors. Since 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 automat-
ically by the xterm terminal emulator. However, when you
log into another machine on a network, you will need to set
DISPLAY by hand to point to your display. For example,
% setenv DISPLAY myws:0
$ DISPLAY=myws:0; export DISPLAY
The xon script 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" com-
mand 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 con-
tacting 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.
TCP/IP
The hostname part of the display name should be the
server machine's IP address name. Full Internet
names, abbreviated names, and IP addresses are all
allowed. For example: x.org:0, expo:0,
198.112.45.11:0, bigmachine:1, and hydra:0.1.
DECnet
The hostname part of the display name should be the
server machine's nodename, followed by two colons
instead of one. For example: myws::0, big::1, and
hydra::0.1.
ACCESS CONTROL
An X server can use several types of access control.
Mechanisms provided in Release 6 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.
MIT-KERBEROS-5 Kerberos Version 5 user-to-user.
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 direc-
tory 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. Other-
wise, 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 net-
work 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 seman-
tics of the particular authorization data to know if this is
actually a problem.
For more information on access control, see the Xsecurity
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 pre-
ferred 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 coor-
dinate 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 Window System 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 Window System
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 exam-
ple, 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 instal-
lations 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 con-
taining the second zero is for the point size; replace it
with a specific size in decipoints (there are 722.7 deci-
points to the inch) to name a font at that size. The last
zero is an average width field, measured in tenths of pix-
els; 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.
One of the following forms can be used to name a font server
that accepts DECnet connections:
decnet/nodename::font$objname
decnet/nodename::font$objname/cataloguelist
The nodename specifies the name (or decimal numeric address)
of the machine on which the font server is running. The
objname is a normal, case-insensitive DECnet object name.
The cataloguelist specifies a list of catalogue names, with
'+' as a separator.
Examples: DECnet/SRVNOD::FONT$DEFAULT,
decnet/44.70::font$special/symbols.
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 <XRoot>/lib/X11/rgb.txt,
where <XRoot> is replaced by the root of the X11 install
tree.
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:" syn-
tax, 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 inten-
sity, 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 physi-
cal 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 key-
codes to keysyms:
modifier list
Some keys (such as Shift, Control, and Caps Lock)
are known as modifier and are used to select dif-
ferent 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 con-
tains 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 con-
tains 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 display-
ing 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 iconi-
fied 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 invo-
cations 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 swap-
ping 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 asynchro-
nously. 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 iden-
tifying 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 prefer-
ences easier, X provides a mechanism for storing default
values for program resources (e.g. background color, window
title, etc.) 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 "." char-
acters, otherwise the sequence will be replaced with a sin-
gle "*" 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 ``\new-
line'' (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 data-
base 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 pre-
cedence) 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 Tookit 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 fre-
quently 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 XUSER-
FILESEARCHPATH or the environment variable XAPPLRES-
DIR (which names a single directory and should end
with a '/' on POSIX systems), plus directories in a
standard place (usually under <XRoot>/lib/X11/, but
this can be overridden with the XFILESEARCHPATH
environment variable) are searched for for
application-specific resources. For example, appli-
cation default resources are usually kept in
<XRoot>/lib/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 conven-
tion, the instance name of a resource begins with a lower-
case 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 Fore-
ground 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 automati-
cally loading resources. See the Xlib manual section
Resource Manager Functions for more information.
EXAMPLES
The following is a collection of sample command lines for
some of the more frequently used commands. For more infor-
mation 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 $*
% xon filesysmachine xload
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 diagnos-
tic messages when errors occur. The defaults for these
messages are usually stored in <XRoot>/lib/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
StringConversionsWarning 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
XProjectTeam(1), XStandards(1), Xsecurity(1),
appres(1), bdftopcf(1), bitmap(1), editres(1), fsinfo(1),
fslsfonts(1), fstobdf(1), iceauth(1), imake(1), lbxproxy(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),
xieperf(1), xinit(1), xkbbell(1), xkbcomp(1), xbkevd(1),
xkbprint(1), xkbvleds(1), xkbwatch(1), xkill(1), xlogo(1),
xlsatoms(1), xlsclients(1), xlsfonts(1), xmag(1), xmh(1),
xmodmap(1), xon(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), Xdec(1), XmacII(1),
Xsun(1), Xnest(1), Xvfb(1), XF86_Acc(1), XF86_Mono(1),
XF86_SVGA(1), XF86_VGA16(1), XFree86(1), kbd_mode(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. The Release 6.4 distribu-
tion is brought to you by The Open Group X Project Team.
The names of all people who made it a reality will be found
in the individual documents and source files. The The X
Project Team staff members responsible for this release are:
Arthur Barstow, Kaleb Keithley, Sekhar Makkapati, M. S.
Ramesh, Jingping Ge, Ken Flowers, and Dave Knorr.
The X Window System standard was originally developed at the
Laboratory for Computer Science at the Massachusetts Insti-
tute 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.
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