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X - a portable, network-transparent window system
SYNOPSIS
The X Window System is a network transparent window system
developed at MIT which runs on a wide range of computing
and graphics machines. It should be relatively straight-
forward to build the MIT software distribution on most
ANSI C and POSIX compliant systems. Commercial implemen-
tations are also available for a wide range of platforms.
The X Consortium 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 Massachusetts Insti-
tute of Technology.
DESCRIPTION
X Window System servers run on computers with bitmap dis-
plays. 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 sys-
tems) as well.
X supports overlapping hierarchical subwindows and text
and graphics operations, on both monochrome and color dis-
plays. 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. Pro-
grams provided in the core MIT distribution include: a
terminal emulator (xterm), a window manager (twm), a dis-
play manager (xdm), a console redirect program (xconsole),
mail managing utilities (xmh and xbiff), a manual page
browser (xman), a bitmap editor (bitmap), a resource edi-
tor (editres), a ditroff previewer (xditview), access con-
trol programs (xauth and xhost), user preference setting
programs (xrdb, xcmsdb, xset, xsetroot, xstdcmap, and
xmodmap), a load monitor (xload), clocks (xclock and
oclock), a font displayer (xfd), utilities for listing
information about fonts, windows, and displays (xlsfonts,
xfontsel, xwininfo, xlsclients, xdpyinfo, and xprop), a
diagnostic for seeing what events are generated and when
(xev), screen image manipulation utilities (xwd, xwud,
xpr, and xmag), and various demos (xeyes, ico, xgc,
x11perf, etc.).
Many other utilities, window managers, games, toolkits,
etc. are included as user-contributed software in the MIT
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
initial set of client applications started. The particu-
lar method used depends on what operating system you are
running and on 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 dis-
play, 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 manually. If this is true for your machine,
your site administrator will probably have pro-
vided 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 prospective, 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 moni-
tors):
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 key-
board and pointer (mouse, tablet, etc.). Most
workstations tend to only have one keyboard, and
therefore, only one display. Larger, multi-user
systems, however, will 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 dis-
play 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, then 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'll
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"
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 mem-
ory, 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 sup-
port 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 IP address name. Full Inter-
net names, abbreviated names, and IP addresses are
all allowed. For example: expo.lcs.mit.edu:0,
expo:0, 18.30.0.212:0, 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 5 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.
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 connec-
tions 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, then 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 envi-
ronments this level of security is not a concern, but if
it is, you need to know the exact semantics of the partic-
ular 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 win-
dow.
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 cor-
responding edge of the window. The X offset may be speci-
fied 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. Win-
dows 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 will be
placed in roughly the center of the screen and a load
average monitor, mailbox, and clock will be 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 spe-
cial programs called window managers. Although many win-
dow 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 MIT 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 MIT 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 scal-
able 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 sig-
nificantly 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. The most common fonts use by X servers
and font servers can be found in four directories:
/usr/lib/X11/fonts/misc
This directory contains many miscellaneous bitmap
fonts that are useful on all systems. It contains
a family of fixed-width fonts, a family of fixed-
width fonts from Dale Schumacher, several Kana
fonts from Sony Corporation, two JIS Kanji fonts,
two Hangul fonts from Daewoo Electronics, two
Hebrew fonts from Joseph Friedman, the standard
cursor font, two cursor fonts from Digital Equip-
ment Corporation, and cursor and glyph fonts from
Sun Microsystems. It also has various font name
aliases for the fonts, including fixed and vari-
able.
/usr/lib/X11/fonts/Speedo
This directory contains outline fonts for Bit-
stream's Speedo rasterizer. A single font face,
in normal, bold, italic, and bold italic, is pro-
vided, contributed by Bitstream, Inc.
/usr/lib/X11/fonts/75dpi
This directory contains bitmap fonts contributed
by Adobe Systems, Inc., Digital Equipment Corpora-
tion, Bitstream, Inc., Bigelow and Holmes, and Sun
Microsystems, Inc. for 75 dots per inch displays.
An integrated selection of sizes, styles, and
weights are provided for each family.
/usr/lib/X11/fonts/100dpi
This directory contains 100 dots per inch versions
of some of the fonts in the 75dpi directory.
Bitmap font files are usually created by compiling a tex-
tual font description into binary form, using bdftopcf.
Font databases are created by running the mkfontdir pro-
gram 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 pix-
els 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 run-
ning. 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 separa-
tor.
Examples: tcp/expo.lcs.mit.edu:7000,
tcp/18.30.0.212:7001/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$objname/cataloguelist
The nodename specifies the name (or decimal numeric
address) of the machine on which the font server is run-
ning. The objname is a normal, case-insensitive DECnet
object name. The cataloguelist specifies a list of cata-
logue names, with '+' as a separator.
Examples: DECnet/SRVNOD::FONT$DEFAULT, dec-
net/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
/usr/lib/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:" 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
intensity, and so on. These values will be gamma cor-
rected 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 val-
ues 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 phys-
ical 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 dif-
ferent symbols that are attached to a single key
(such as Shift-a generates a capital A, and Con-
trol-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 modi-
fier keys are currently pressed. Most servers set
up this list to initially contain the various
shift, control, and shift lock keys on the key-
board.
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 initial-
ized by the server to correspond to normal type-
writer 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 con-
ventions 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 modi-
fier." 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. Other-
wise, 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 alpha-
betic, 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 follow-
ing options:
-display display
This option specifies the name of the X server to
use.
-geometry geometry
This option specifies the initial size and loca-
tion 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 dis-
playing 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 distin-
guish between invocations of an application, with-
out resorting to creating links to alter the exe-
cutable 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
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 appli-
cation 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 prefer-
ences easier, X provides a mechanism for storing default
values for program resources (e.g. background color, win-
dow 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 fash-
ion, 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 pro-
gram 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 inter-
preted 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 multi-
ple 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 recog-
nized 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 can-
not 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 com-
ponent at a time. At each level, the corresponding compo-
nent 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 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
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, plus directories in a standard place
(usually under /usr/lib/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/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 exe-
cuting.
-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 com-
mand 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, applica-
tion 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 .Xre-
sources in your home directory, they could be added to any
existing resources in the server with the following com-
mand:
% 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 automat-
ically 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
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 $*
% xon filesysmachine xload
DIAGNOSTICS
A wide variety of error messages are generated from vari-
ous programs. The default error handler in Xlib (also
used by many toolkits) uses standard resources to con-
struct diagnostic messages when errors occur. The
defaults for these messages are usually stored in
/usr/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 fail-
ing. 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 (fre-
quently 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
For more information on the X server:
Xserver(9), XMachTen(9)
For more information on clients, utilities, and demos:
appres(9), auto_box(9), bdftopcf(9), beach_ball(9),
bitmap(9), editres(9), fs(9), fsinfo(9), fslsfonts(9),
fstobdf(9), ico(9), imake(9), listres(9), lndir(9),
makedepend(9), maze(9), mkdirhier(9), mkfontdir(9),
oclock(9), plbpex(9), puzzle(9), resize(9), showfont(9),
showrgb(9), twm(9), viewres(9), x11perf(9),
x11perfcomp(9), xauth(9), xbiff(9), xcalc(9), xclip-
board(9), xclock(9), xcmsdb(9), xcmstest(9), xconsole(9),
xcutsel(9), xditview(9), xdm(9), xdpr(9), xdpyinfo(9),
xedit(9), xev(9), xeyes(9), xfd(9), xfontsel(9), xgas(9),
xgc(9), xhost(9), xinit(9), xkill(9), xload(9), xlogo(9),
xlsatoms(9), xlsclients(9), xlsfonts(9), xmag(9), xman(9),
xmh(9), xmkmf(9), xmodmap(9), xon(9), xpr(9), xprop(9),
xrdb(9), xrefresh(9), xset(9), xsetroot(9), xstdcmap(9),
xterm(9), xwd(9), xwininfo(9), xwud(9)
For more information on X specifications:
Xlib - C Language X Interface, and X Toolkit Intrinsics -
C Language Interface
COPYRIGHT
The following copyright and permission notice outlines the
rights and restrictions covering most parts of the core
distribution of the X Window System from MIT. Other parts
have additional or different copyrights and permissions;
see the individual source files.
Copyright 1984, 1985, 1986, 1987, 1988, 1989, 1990, 1991
by the Massachusetts Institute of Technology.
Permission to use, copy, modify, distribute, and sell this
software and its documentation for any purpose is hereby
granted without fee, provided that the above copyright
notice appear in all copies and that both that copyright
notice and this permission notice appear in supporting
documentation, and that the name of MIT not be used in
advertising or publicity pertaining to distribution of the
software without specific, written prior permission. MIT
makes no representations about the suitability of this
software for any purpose. It is provided "as is" without
express or implied warranty.
TRADEMARKS
X Window System is a trademark of MIT.
AUTHORS
A cast of thousands, literally. The MIT Release 5 distri-
bution is brought to you by the MIT X Consortium. The
names of all people who made it a reality will be found in
the individual documents and source files. The staff mem-
bers at MIT responsible for this release are: Donna Con-
verse (MIT X Consortium), Stephen Gildea (MIT X Consor-
tium), Susan Hardy (MIT X Consortium), Jay Hersh (MIT X
Consortium), Keith Packard (MIT X Consortium), David
Sternlicht (MIT X Consortium), Bob Scheifler (MIT X Con-
sortium), and Ralph Swick (Digital/MIT Project Athena).
X Version 11 Release 5 18
