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.