NAME

X - a portable, network transparent window system

SYNOPSIS

X is a network transparent window system developed at MIT which runs under a wide variety of operating systems.  The standard distribution from MIT works on Ultrix-32 Version 1.2 (and higher), 4.3BSD Unix, SunOS 3.2 (and higher), HP-UX 6.01, and DOMAIN/IX 9.7.  In addition, many vendors support the X Window System under other operating systems. 

THE OFFICIAL NAMES

The official names of the software described herein are:

X
X Window System
X Version 11
X Window System, Version 11
X11

Note that the phrases X.11, X-11, X Windows or any permutation thereof, are explicity excluded from this list and should not be used to describe the X Window System (window system should be thought of as one word).

X Window System is a trademark of the Massachusetts Institute of Technology. 

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 functions, see the Xlib - C Language X Interface manual, the X Window System Protocol specification, and various toolkit documents. 

When you first log in on a display running X, you are usually using the xterm(1) terminal emulator program.  You need not learn anything extra to use a display running X as a terminal beyond moving the mouse cursor into the login window to log in normally. 

The core X protocol provides mechanism, not policy.  Windows are manipulated (including moving, resizing and iconifying) not by the server itself, but by a separate program called a “window manager” of your choosing.  This program is simply another client and requires no special privileges.  If you don’t like the ones that are supplied (see uwm(1) and wm(1)), you can write your own. 

The number of programs that use X is growing rapidly.  Of particular interest are: a terminal emulator (xterm(1)), window managers (wm(1) and uwm(1)), a mailer reader (xmh(1)), a bitmap editor (bitmap(1)), an access control program (xhost(1)), user preference setting programs (xset(1), xsetroot(1), and xmodmap(1)), a load monitor (xload(1)), clock (xclock(1)), a font displayer (xfd(1)), a protocol translator for running X10 programs (x10tox11(1)), and various demos (ico(1), muncher(1), puzzle(1), etc.). 
 

DISPLAY SPECIFICATION

When you first log in, the environment variable DISPLAY will be set to a string specifying the name of the machine on which the server is running, a number indicating which of possibly several servers to use, and possibly a number indicating the default screen of the server (usually this is omitted and defaults to 0).  By convention, servers on a particular machine are numbered starting with zero.  The format of the DISPLAY string depends on the type of communications channel used to contact the server. 
 
The following connection protocols are supported:

TCP/IP
DISPLAY should be set to “host:dpy.screen” where host is the symbolic name of the machine (e.g. expo), dpy is the number of the display (usually 0), and screen is the number of the screen.  The screen and preceding period are optional, with the default value being zero (0).  Full Internet domain names (e.g. expo.lcs.mit.edu) are allowed for the host name. 

Unix domain
DISPLAY should be set to “unix:dpy.screen”, where dpy is the display number and screen is the screen number; screen and the preceding period are optional, with the default value being zero (0). 

DECnet
DISPLAY should be set to “nodename::dpy.screen” where nodename is the symbolic name of the machine, dpy is the display number, and screen is the screen number; screen and the preceding period are optional, with the default value being zero (0). 

Most programs accept a command line argument of the form “-display display” that can be used to override the DISPLAY environment variable. 

GEOMETRY SPECIFICATION

One of the advantages of using window systems over 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, most applications accept a command line argument that is treated as the prefered size and location for this particular application’s window. 

This argument, usually specified as “-geometry WxH+X+Y,” indicates that the window should have a width of W and height of H (usually measured in pixels or characters, depending on the application), and the upper left corner X pixels to the right and Y pixels below the upper left corner of the screen (origin (0,0)).  “WxH” can be omitted to obtain the default application size, or “+X+Y” can be omitted to obtain the default application position (which is usually then left up to the window manager or user to choose).  The X and Y values may be negative to position the window off the screen.  In addition, if minus signs are used instead of plus signs (e.g. WxH-X-Y), then (X,Y) represents the location of the lower right hand corner of the window relative to the lower right hand corner of the screen. 

By combining plus and minus signs, the window may be place relative to any of the four corners of the screen.  For example:

555x333+11+22
This will request a window 555 pixels wide and 333 pixels tall, with the upper left corner located at (11,22).

300x200-0+0
This will request a window measuring 300 by 200 pixels in the upper right hand corner of the screen.

48x48--5--10
This will request a window measuring 48 by 48 pixels whose lower right hand corner is 5 pixel off the right edge and the screen and 10 pixels off the bottom edge.

COMMAND LINE ARGUMENTS

Most X programs attempt to use a common set of names for their command line arguments.  The X Toolkit automatically handles the following arguments:

−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.

−display display
This option specifies the name of the X server to use.

−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.

−geometry geometry
This option specifies the initial size and location of the window.

−iconic
This option indicates that application should start out in an iconic state. Note that how this state is represented is controlled by the window manager that the user is running.

−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.

−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.

−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 explicitly command line arguments.

RESOURCES

To make the tailoring of applications to personal preferences easier, X supports several mechanisms for storing default values for program resources (e.g. background color, window title, etc.)  Resources are specified as strings of the form “name∗subname∗subsubname...: value” (see the Xlib manual section Using the Resource Manager for more details) that are loaded into a client when it starts up.  The Xlib routine XGetDefault(3X) and the resource utilities within the X Toolkit obtain resources from the following 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 using the xrdb(1) program. 

application-specific directory
Any application- or machine-specific resources can be stored in the class resource files located in the XAPPLOADDIR directory (this is a configuration parameter that is /usr/lib/X11/app-defaults in the standard distribution).

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, the X Toolkit looks for a file named .Xdefaults-hostname, where hostname is the name of the host where the application is executing. 

−xrm resourcestring
Applications that use the X Toolkit can have resources 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 “instance” resources 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 concatentated with the first letter of the succeeding words capitalized.  Applications written with the X Toolkit 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 X Toolkit applications 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. 

When a named resource is unavailable (for example, a color named chartrusse or a font named teeneyweeney), normally no error message will be printed; whether or not useful results ensue is dependent on the particular application.  If you wish to see error messages (for example, if an application is failing for an unknown reason), you may specify the value “on” for the resource named “StringConversionWarnings.”  If you want such warnings for all applications, specify “∗StringConversionWarnings:on” to the resource manager.  If you want warnings only for a single application named “zowie”, specify “zowie∗StringConversionWarnings:on” to the resource manager. 

DIAGNOSTICS

The default error handler uses the Resource Manager to build diagnostic messages when error conditions arise.  The default error database is stored in the file XErrorDB in the directory specified by the LIBDIR configuration parameter (/usr/lib/X11 in the standard distribution).  If this file is not installed, error messages will tend to be somewhat cryptic. 

SEE ALSO

xterm(1), bitmap(1), ico(1), muncher(1), plaid(1), puzzle(1), resize(1), uwm(1), wm(1), x10tox11(1), xbiff(1), xcalc(1), xclock(1), xedit(1), xfd(1), xhost(1), xinit(1), xload(1), xlogo(1), xlsfonts(1), xmh(1), xmodmap(1), xpr(1), xprkbd(1), xprop(1), xrdb(1), xrefresh(1), xset(1), xsetroot(1), xwd(1), xwininfo(1), xwud(1), Xserver(1), Xapollo(1), Xqdss(1), Xqvss(1), Xsun(1), kbd_mode(1), todm(1), tox(1), biff(1), init(8), ttys(5), Xlib − C Language X Interface, X Toolkit Intrinsics - C Language X Interface

COPYRIGHT

The following copyright and permission notice outlines the rights and restrictions covering most parts of the standard 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, Massachusetts Institute of Technology. Permission to use, copy, modify, and distribute this software and its documentation for any purpose and without fee is hereby granted, 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 M.I.T. not be used in advertising or publicity pertaining to distribution of the software without specific, written prior permission. M.I.T. makes no representations about the suitability of this software for any purpose.  It is provided "as is" without express or implied warranty. This software is not subject to any license of the American Telephone and Telegraph Company or of the Regents of the University of California.

AUTHORS

It is no longer feasible to list all people who have contributed something to X, but see doc/contributors in the standard sources. 
 

X Version 11  —  1 March 1988