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The X Window User HOWTO

Christopher Yeleighton


Hal Burgiss


   v4.0 Jan. 12th, 2010
   Revision History
   Revision v4.0 2010-01-12 Revised by: cy
   Converted to XML docbook and to the new domain.
   Revision v3.1 2002-10-10 Revised by: hb
   Some minor additions and updates.
   Revision v3.0 2002-03-06 Revised by: hb
   Rewrite of the original document. Convert to DocBook. Many, many

   This document provides basic information on understanding and
   configuring the X Window System for Linux users. This is meant to be
   an introductory level document. A basic knowledge of software
   configuration is assumed, as is the presence of an installed and
   working X Window System.

   Table of Contents
   1. Introduction

        1.1. New Versions and ChangeLog
        1.2. To Do
        1.3. Feedback
        1.4. Help!
        1.5. Acknowledgments
        1.6. Copyright
        1.7. Standard Disclaimer

   2. XFree86

        2.1. Hardware
        2.2. XF86Config
        2.3. xvidtune and Monitor Tuning

   3. Running X

        3.1. startx
        3.2. Display Managers

   4. More X Configuration

        4.1. X Resources
        4.2. xmodmap, the Keyboard and Mice
        4.3. xset

   5. Fonts and Colors

        5.1. Fonts Demystified
        5.2. Colors

   6. Window Managers and Desktops

        6.1. Window Managers
        6.2. Desktop Environments

   7. X and the Command Line

        7.1. xterm and friends

   8. X Networking and Security
   9. Performance Considerations

        9.1. Hardware
        9.2. Memory
        9.3. X over the Network
        9.4. Other Tips

   10. Appendix

        10.1. Terminology and Usage
        10.2. Links and other References

1. Introduction

   The X Window System is an advanced, graphical computing and network
   environment that was designed from the ground up as a multi-user
   system. X was first released in 1984. If you are not familiar with
   the basic concepts surrounding X and it's related components, you
   should first read the X Window System Architecture Overview HOWTO,
   [], to get
   an idea of how the various pieces fit together. There is also an
   attempt to define to various X related terminology in the Appendix,
   if concepts such as "displays" and "X clients" in this context are
   confusing to you.

   This document will address basic X Window configuration and usage on
   Linux. We will also look at how X is commonly started in Linux, and
   how the start up can be configured, and related issues. We will not
   examine Window Manager (e.g. fvwm), or Desktop Environment (KDE and
   GNOME) configuration. There are just too many variables there, and
   the pace of change moves too quickly. Of course, to a large extent
   the user interacts more directly with these components than the X
   server itself, so additional reading would be worthwhile. Check your
   locally installed documentation, and the respective home pages for
   more information.

   Some other important points to remember here:

     * X is a client-server, multi-user system in every respect, and not
       just a GUI.
     * X is not integrated into the operating system, and rides on top
       of it, like other servers.
     * X is an open standard, and runs on many platforms.
     * What you actually see on the screen is the result of various
       components, all working together: operating system, X, Window
       Manager, and optionally, a desktop environment like GNOME or KDE.
       These are all "plug and play" components, meaning you can
       interchange an individual component without touching the other
     * Each of the various components has its own configuration. This
       makes for a very flexible, and potentially very robust, system.
       It also adds complexity.

   The discussion here will be limited to X as implemented by The
   XFree86 Project, Inc. on Linux. There are other implementations,
   including commercial ones. XFree86 v4.x has been out for some time
   now, so we will be assuming that version. Much of the discussion
   applies to the previous 3.x version as well, but there are some
   occasional differences.

   It is also worth noting that there are conceivably many ways to start
   X, and to set up a Linux system. We will focus on the common methods
   found in Linux distributions. Also, vendors may vary on where they
   put configuration files, and how they name them. Keep this in mind if
   you see such discrepancies in this document. If this is a problem,
   your vendor surely has their own documentation. And as always,
   hopefully the man pages will conform to your installation.

   Also, we will look at various configuration files in the following
   sections. These are all plain text files, and can be edited with your
   favorite editor. Always make a backup copy before editing important
   files, in case Murphy pays a visit (e.g. "cp /etc/X11/XF86Config-4

1.1. New Versions and ChangeLog

   The [] current official
   version of this HOWTO may be found at the Linux Documentation

   v3.1: This is just some small, minor updates. Include link to
   [] as a good
   resource for shopping Window Managers. Add link for fluxbox, a Window
   Manager with Tabbed windows. And add a brief section on improving
   network performance. Verify links all work.

   v3.0: This is a major rewrite with several new sections. Some
   sections were removed, with the focus more now on just X itself (and
   not clients like Window Managers). New maintainer too :-)

   v2.0: includes corrections from Guus Bosch, Brian J. Miller, and
   myself, as well as lots of new updates and info.

   v1.4: include corrections and additions from Anthony J., and some
   very good security tips from Tomasz Motylewski.

1.2. To Do

   A rudimentary troubleshooting section. Probably for v3.2.

1.3. Feedback

   If you have questions or comments about this document, please feel
   free to email me, Hal Burgiss at <>. I welcome any
   suggestions, corrections, or additions. If you have information you
   would like to see in future revisions, or you would like to
   contribute to a future revision, please drop me a note.

1.4. Help!

   I have assumed maintainership of this document because it was
   abandoned, and I had wanted to offer a suggested change. Well, to
   make a long story short, this led to a major re-write. You can help
   make this a better document by correcting inaccuracies, clarifying
   the unclear, and suggesting improvements. There is much about this
   topic I may not know, or not have explained well. Your help will
   improve this document and help other users. This document needs your

1.5. Acknowledgments

   Thanks to the XFree86 development team for their efforts in providing
   a robust and flexible GUI. And to the whole GNU/Linux and Open Source
   community for making it all possible.

   Also, the original author, Ray Brigleb.

   Various users on comp.os.linux.x that have helped in one way or
   another, whether they know it or not.

   Lastly, [], who saved
   me much time with their incredible repository of information. Use it
   to answer questions not answered here!

1.6. Copyright

   Copyright � 2002, Hal Burgiss.

   Unless otherwise stated, Linux HOWTO documents are copyrighted by
   their respective authors. Linux HOWTO documents may be reproduced and
   distributed in whole or in part, in any medium physical or
   electronic, as long as this copyright notice is retained on all
   copies. Commercial redistribution is allowed and encouraged; however,
   the author would like to be notified of any such distributions.

   All translations, derivative works, or aggregate works incorporating
   any Linux HOWTO documents must be covered under this copyright
   notice. That is, you may not produce a derivative work from a HOWTO
   and impose additional restrictions on its distribution. Exceptions to
   these rules may be granted under certain conditions; please contact
   the Linux HOWTO coordinator for more information.

   In short, we wish to promote dissemination of this information
   through as many channels as possible. However, we do wish to retain
   copyright on the HOWTO documents, and would very much like to be
   notified of any plans to redistribute the HOWTOs, this one in

   Some of the terms mentioned in this document are trade names. Unless
   otherwise stated, all trademarks are property of their respective

   "X Window System" is a trademark of the X Consortium, Inc [now the

   "XFree86" is a trademark of The XFree86 Project, Inc.

   "Linux" is a Registered Trademark of Linus Torvalds.

1.7. Standard Disclaimer

   The information and examples given here are for illustrative
   purposes. Use at your own risk. Every attempt has been made to insure
   that the content of this document was accurate when written. If you
   find inaccuracies, please send me clarifications.

   References to any particular company, product or brand name should
   not be construed as an endorsement.

2. XFree86

   Virtually every Linux distribution comes with XFree86's X Window
   System implementation. This project, of course, provides us the X
   server, but also includes an extensive suite of utilities and
   applications to help implement a fully functional GUI environment.

   In fact, the list would be just too long to list everything that
   comes with XFree86. In addition to the X server itself, here are a
   few of the noteworthy utilities:

   xdm - the X Display Manager.

   xfs - the X Font Server.

   twm - a lightweight Window Manager.

   xterm - the best known terminal emulator. Also, xterm3d and nxterm.

   xwd - a screen and window image capturer.

   xf86config - X server configuration utility.

   xdpyinfo - X display information utility. This shows great detail
   about the X server.

   xlsclients - lists currently connected X server clients.

   xlsfonts - lists fonts available to X.

   appres - lists the X "resources" that a program will use.

   xfontsel - an application for viewing or selecting fonts.

   xprop - a tool for displaying window "properties", such as the Class
   name of the client.

   xset - sets user preferences for many things, including mouse,
   keyboard, sound (bell), etc.

   xsetroot - a program for changing the "root window" appearance, e.g.
   setting a background color.

   xvidtune - an application to adjust X server video modes and monitor
   related settings.

   xwininfo - displays information about a selected "window".

   xmodmap - a utility for manipulating keyboard and mouse button

   Many, many fonts. And quite a bit of documentation as well.

   There are many more. We'll just touch on a few of these utilities
   here. But feel free to explore the others. Most should have their own
   man pages.

2.1. Hardware

   The X server controls both input (keyboard, mouse, etc) and output
   (display, monitor) devices.

   Compatible hardware is a tough topic, since it is very much a moving
   target. We are forced here to avoid specifics, since this would
   surely change by the time you read this. And would be tediously
   lengthy anyway.

   So let's settle for some generalities. Most PC type hardware is
   supported to one degree or another. Big help ;-)

   Rule of thumb: if it is a device that uses a long-standing,
   commonplace protocol (e.g. PS/2), it should be well supported.
   Conversely, if it is something relatively new, with ground-breaking
   technology, the odds are not as good. This is just the nature of the
   beast with open source development versus manufacturers that cater
   more to the most popular platforms. Some manufacturers are more
   co-operative than others too.

   Now, some general guidelines:

     * Monitors - This is easy. Linux does not really need to be
       compatible with the monitor per se. That is the job of the video
       card. Any monitor that your graphics card can drive should do
       fine. Including, flat panel monitors.
     * Video cards - This is much tougher. The X server is determined by
       the the chipset. Many, many are supported. But inevitably there
       are always some newer cards, or even revised cards, that are not.
       And some may have better support and better optimization than
       others. Advanced features such as multi-headed displays, 3D, TV
       out, DRI, etc., have some support as well, though this should be
       researched first, as the support may be limited. Supported cards
       are listed: []
       Open source drivers are often developed incrementally. For
       instance, a particular card may work well for basic display
       purposes, but specialized features such as 3D may come much later
       in the development cycle. This is a quite different development
       model than with proprietary drivers from the manufacturer.
     * Keyboards -- Any standard PC type keyboard should do fine,
       including PS/2, USB and many infra-red devices. Probably many
       "non-standard" ones too ;-)
     * Mice and other pointer devices -- Most should be supported
       including PS/2, bus, serial, USB and many infra-red devices.
       Optical mice also. Unix has long preferred three button mice,
       though more buttons is supported as well. Many wheeled mice have
       X server support via the "IMPS/2" (IntelliMouse), or other
       specific protocols, though may require supplemental configuration
       for some individual applications. (See the Links section.)
     * Laptops have their own unique set of problems since the hardware
       tends to be very specialized, and often different from what is
       commonly found on desktop style systems. X is supported by many.
       Check for details at []

   You can check the "hardware compatibility list" at your
   distribution's web site too. This should give a very good idea of
   what should work with your release.

   Newer versions of XFree86 obviously will have better hardware
   support. If you are using an older Linux version and don't have full
   hardware support, see about upgrading XFree86. Check first to see if
   your distribution has updates for your release.

2.2. XF86Config

   The primary configuration file for XFree86 is XF86Config, which may
   exist on your system as XF86Config-4 for XFree86 v4.x, or possibly
   other variations (see man page). It is typically located as
   /etc/X11/XF86Config, though again, there may be variations in the
   path. If both a XF86Config-4 and XF86Config exist, XFree86 v4.x will
   use the former. This is a required file.

   XF86Config file defines hardware devices, and other critical
   components of the X server environment.

   While this is a plain text file, and is editable, it is most often
   created during installation by whatever utility your vendor uses for
   this purpose. XFree86 also includes the xf86config utility for this,
   but many distributions have their own such utilities. These utilities
   can be run after installation if need be, to alter the configuration,
   or if new hardware is installed. Read your locally installed
   documentation first. If you attempt to hand edit this file, be sure
   to make a backup copy first since X will not start if this file is
   not to its liking ;-)

   This file contains various "sections". Each section defines some
   fundamental aspect of XFree86, such as "InputDevice" (mouse,
   keyboard, joystick, etc), "monitor", or "screen". The XF86Config man
   page describes the sections and common values for each. Note that the
   values listed in the man page is not a comprehensive listing. There
   are many device specific "options". Check [] for notes and tips on your hardware.

   The author's current XF86Config-4, as generated by Red Hat's
   installer for XFree86 4.1:

Section "ServerLayout"
        Identifier "XFree86 Configured"
        Screen      0  "Screen0" 0 0
        InputDevice    "Mouse0" "CorePointer"
        InputDevice    "Keyboard0" "CoreKeyboard"

Section "Files"
   # The location of the RGB database.
   RgbPath     "/usr/X11R6/lib/X11/rgb"

   # Multiple FontPath entries are allowed (they are concatenated together)
   # By default, Red Hat 6.0 and later now use a font server independent of
   # the X server to render fonts.
   FontPath "unix/:7100"

# Module loading section

Section "Module"
        Load  "dbe"             # Double-buffering
        Load  "GLcore"          # OpenGL support
        Load  "dri"             # Direct rendering infrastructure
        Load  "glx"             # OpenGL X protocol interface
        Load  "extmod"          # Misc. required extensions
        Load  "v4l"             # Video4Linux
#    Load  "fbdevhw"
     Load  "pex5"
     Load  "record"
     Load  "xie"

Section "InputDevice"
        Identifier  "Keyboard0"
        Driver      "keyboard"
        Option      "XkbLayout" "us"

#    Option  "AutoRepeat"    "500 5"

# when using XQUEUE, comment out the above line, and uncomment the
# following line
#    Option  "Protocol"      "Xqueue"

# Specify which keyboard LEDs can be user-controlled (eg, with xset(1))
#    Option  "Xleds"         "1 2 3"

# To disable the XKEYBOARD extension, uncomment XkbDisable.
#    Option  "XkbDisable"

# To customize the XKB settings to suit your keyboard, modify the
# lines below (which are the defaults).  For example, for a non-U.S.
# keyboard, you will probably want to use:
#   Option  "XkbModel"      "pc102"
# If you have a US Microsoft Natural keyboard, you can use:
#   Option  "XkbModel"      "microsoft"

Section "InputDevice"
        Identifier  "Mouse0"
        Driver      "mouse"
        Option      "Device" "/dev/mouse"
        Option      "Protocol" "IMPS/2"
        Option      "Emulate3Buttons" "off"
        Option      "ZAxisMapping" "4 5"

Section "Monitor"
        Identifier "Sylvania F74"
        VendorName "Unknown"
        ModelName  "Unknown"
        HorizSync   30 - 70
        VertRefresh 55 - 120
        Option "dpms"
#    Modelines go here if necessary. Use xvidtune to get proper values.

Section "Device"
        Identifier "ATI Rage 128"
        Driver "r128"
        BoardName "Unknown"

Section "Device"
        Identifier "Linux Frame Buffer"
        Driver "fbdev"
        BoardName "Unknown"

Section "Screen"
        Identifier "Screen0"
        Device "ATI Rage 128"
        Monitor "Sylvania F74"
        DefaultDepth 24
        Subsection "Display"
                Depth 24
                Modes "1400x1050" "1280x1024" "1152x864" "1024x768" "800x600"
        Subsection "Display"
                Depth 16
                Modes "1600x1200" "1400x1050" "1280x1024" "1152x864" "1024x768
" "800x600"
        Subsection "Display"
                Depth 8
                Modes "1024x768" "800x600" "640x480"

Section "DRI"
        Mode 0666

   Yours may look quite different. This is just one possible
   configuration with gratuitous comments from Red Hat (and me), and is
   for a fairly ordinary set up. There is nothing exotic here like
   multiple screens or displays.

   It is beyond the scope of this document to explain this in detail.
   See the XF86Config man page. Also, consider visiting
   [] and look for specific options that
   might apply to your card or other hardware.

   Just one quick note on the "Screen" section above. Notice there are
   three sub-sections, identified as "Display". Each sub-section has a
   different "Depth" specified, (a.k.a. ColorDepth). The "Modes" also
   vary somewhat according to the respective "Depth" setting. The active
   "Display" sub-section that will be used, is determined by the
   "DefaultDepth" setting (unless over-ridden by command line options).
   The default in this example is defined as "24", so the first
   sub-section will be used. Also, the highest "Mode" listed in this
   sub-section will be the default mode (resolution), which here is the
   first one listed. The first listed mode also determines the viewable
   screen area, which can be smaller than the mode (resolution) itself.
   In which case, you would have a virtual desktop that is larger than
   the viewable screen. To have the viewable screen, and resolution
   match, have the largest value as the first value listed for each

   Another note on the "Modes" here: what you see is the result of my
   choices during Red Hat's Xconfigurator's configuration. These are
   standard resolutions, but do not have to be! This is only limited by
   what your hardware can support. And you don't have to use standard
   width x height ratios either. Something like 1355x1112 is a valid
   setting (if your hardware supports it and it floats your boat!).

   The X server will reject any "Modes" it thinks are invalid. You can
   cycle through valid modes to change screen resolution with Ctrl-Alt-+
   and Ctrl-Alt-- (that's the keypad plus and minus keys).

   In versions prior to v4.x, you would also see many "Modeline"
   statements that attempted to define the monitor's capabilities. These
   statements would look something like:

 # 1024x768 @ 100Hz, 80.21 kHz hsync
 Modeline "1024x768"  115.5  1024 1056 1248 1440  768  771  781  802 -HSync -V

   Explicit "Modeline" definitions are not required as of 4.x ;-) This
   sometimes required hand editing to get optimal values in earlier
   versions of XFree86, though is generally not necessary with v4.x. The
   XFree86 Video Timings HOWTO has a nice, but rather technical,
   explanation of this.

   If whatever configuration utility you are using, does not
   automatically recognize your video card or monitor specifications
   correctly, you are unlikely to get an optimal configuration. In such
   cases, you may have to manually supply the correct values. This
   should be available from your owner's manual (you kept that, right?).
   Or, check the manufacturer's web site.

   Again, hand editing of this file is generally unnecessary. Should you
   decide this is indeed necessary, be careful. One small error may
   cause X to fail. Any changes to this file will require restarting X
   for the changes to take effect.

   Using somebody else's XF86Config file, is generally a bad idea since
   they are unlikely to have identical hardware.

2.3. xvidtune and Monitor Tuning

   You probably want to get the most out of your hardware. If X isn't
   configured optimally, consider re-running your vendor's X
   configuration utility and try to get better results. It is highly
   unlikely that you could hurt anything by experimenting. Most modern
   monitors now have safeguards that prevent a meltdown ;-)

   If you over-do it though X may not be able to start. For this reason,
   I prefer to use the "startx" way of starting X (see below) while
   "experimenting". This way if X crashes, the display manager (GUI
   login) will not loop and cause you severe headaches. startx just
   gracefully goes back to a text console screen, where an error message
   may be visible.

   Another way of tweaking monitor related settings is with XFree86's
   xvidtune program. This is run interactively and can be used to adjust
   various settings (see man page). The simple dialog box has sliders
   and buttons that allow user input and adjustment. The top part has
   horizontal monitor settings on the left, and vertical settings on the
   right. The buttons just below the sliders can be used to adjust each.

   This is sometimes used to adjust the viewable screen area, such as to
   center it, or increase its size to fill the monitor's viewport. When
   xvidtune is launched, it defaults to the current settings.

   The bottom left corner has buttons that can "Apply" new settings,
   "Test" new settings, or "Show" current settings (i.e. dump to
   screen), among other things. Any changes made here are not saved. If
   new settings are "Applied", it is just for the current session.
   Example output of xvidtune "Show":

 Vendor: Unknown, Model: Unknown
 Num hsync: 1, Num vsync: 1
 hsync range 0:  30.00 -  70.00
 vsync range 0:  55.00 - 120.00
 "1400x1050"   122.00   1400 1488 1640 1880   1050 1052 1064 1082 +hsync +vsyn

   The last line is the "Modeline" being used to drive the current
   screen. See The XFree86 Video Timings HOWTO , for more on

   You can test modifications, and apply them to the current session.
   For changes to be made permanent, they will have to be added manually
   to the "Monitor" section of XF86Config (or XF86Config-4 for v.4.x)
   with a text editor.

   xvidtune will dutifully warn of you of the hazards of playing with
   the monitor settings. It is unlikely you can hurt anything with
   modern monitors. But it is best used to make minor adjustments. Use
   at your own risk!

3. Running X

   Starting an X session is typically done in one of two ways: the X
   session is started via a display manager (like xdm), and the user
   logs in at a GUI screen. Or, the user starts X manually after logging
   in to a text console. The latter is typically done with the startx
   command, which is a simple shell script wrapper for xinit. X runs
   with root privileges in either case, since it needs raw access to
   hardware devices.

   Typically, which method is used, is determined by the system
   "runlevel". The default runlevel to launch at boot is generally set
   in /etc/inittab on Linux:

 # Run xdm in runlevel 5
 x:5:respawn:/etc/X11/xdm -nodaemon

   That would start xdm, and thus X, at runlevel 5. It will "respawn",
   if it dies or is stopped for any reason. You can also use the "init"
   command to change runlevels without rebooting (see man page).

   Let's look briefly at both approaches, and then some additional
   configuration to set up the user's working environment.

3.1. startx

   startx will start X by first invoking xinit. By itself, this would
   put you at a blank, fuzzy looking, bare-bones desktop with no Window
   Manager loaded. xinit basically takes two sets of command line
   arguments: client specifications (programs to run, etc), and server
   specifications (X server options), separated by "--". If no client
   program is specified on the command line, xinit will look for a
   .xinitrc file in the user's home directory, to run as a shell script.
   If found, this then would in turn run whatever user specified
   commands to set up the environment, or launch programs that the file
   contained. If this file does not exist, xinit will use the following
   initial command:

 xterm -geometry +1+1 -n login -display :0

   If no .xserverrc is found in the user's home directory, X itself will
   be started with the following command:

 X :0

   As you see, this is not overly helpful as it just launches one xterm.
   The startx shell wrapper provides additional functionality and
   flexibility to xinit. startx will invoke xinit for us, and provide
   some simple configuration options as well. You can also issue
   commands such as the following, for instance:

 startx -- -dpi 100 -depth 16   #force X to 100 dots per inch
                                #and colordepth of 16 (X v4 syntax)

   Anything after the double dashes are passed as arguments directly to
   the X server via xinit. In this example, you can force X to the
   resolution of your preference, and still have it use the
   configuration files we will cover later in this document. See the
   Xserver man page for more command line options.

   Instead of issuing the same command line every time, it is easier to
   use the configuration files to store this type of information for us.

   If you take a look at the startx script (/usr/X11R6/bin/startx on my
   system), you see it uses two default configuration files to help set
   up the X environment: xinitrc and xserverrc. It looks first in
   /etc/X11/xinit/, for the system wide files. It then checks the user's
   home directory for similar files, which will take precedence if
   found. Note that the latter are Unix style "dot" files (e.g.
   ~/.xinitrc), and are executable shell scripts.

   You normally would not want to edit the system wide files, but you
   can freely copy these to your home directory as a starting point, or
   just start from scratch. As you can tell by the names, one helps set
   up the X server, and one sets up xinit by executing commands,
   preparing the environment and possibly starting client programs like
   xterm or a Window Manager (yes, it's a client too).

3.1.1. xserverrc

   As with all XFree86 configuration files, this is a plain text file,
   and is usually a simple, one line statement to start the X server. It
   can include any valid command line options supported by your X
   installation. If you always start X with your own options, this
   should be easier than typing the options each time. One possible

 exec X :0 -dpi 100 -nolisten tcp

   This will start X on display :0, the first "display", at a
   dots-per-inch resolution of 100, and disables TCP connections. See
   the Xserver man page for other valid options. This is just an

3.1.2. xinitrc

   xinitrc is used to set up a suitable X environment, and to launch
   other programs, a.k.a "clients" that we may want available as soon as
   X is started. You likely have a system wide xinitrc to start a
   predefined set off programs. To customize this, create your own in
   your home directory. Name it .xinitrc, make sure it is an executable
   script, and chmod +x. An example (slightly modified from the original
   on my system):

# $XConsortium: xinitrc.cpp,v 1.4 91/08/22 11:41:34 rws Exp $


# merge in defaults and keymaps
if [ -f $userresources ]; then
    xrdb -merge $userresources

if [ -f $usermodmap ]; then
    xmodmap $usermodmap

if [ -z "$BROWSER" ] ; then
        # we need to find a browser on this system
        BROWSER=`which netscape`
        if [ -z "$BROWSER" ] || [ ! -e "$BROWSER" ] ; then
        # not found yet
if [ -z "$BROWSER" ] ; then
        # we need to find a browser on this system
        BROWSER=`which lynx`
        if [ -z "$BROWSER" ] || [ ! -e "$BROWSER" ] ; then
        # not found yet
                BROWSER="xterm -font 9x15 -e lynx"

export BROWSER

# start some nice programs
if [ -f $HOME/.Xclients ]; then
    exec $HOME/.Xclients
    xclock -geometry 50x50-1+1 &
    xterm -geometry 80x50+494+51 &
    if [ -f /usr/X11R6/bin/fvwm ]; then
        exec fvwm
        exec twm


   Briefly, what this script does, is set up our working environment,
   with xmodmap (keyboard) and xrdb (application resource settings).
   More on these below. Then the shell variable $BROWSER is set for a
   GUI environment (Netscape in this example) so that any applications
   that might expect this, have a reasonable choice available. Then the
   presence of the file Xclients is checked, both as a system wide file
   and in the user's home directory. In this particular example, this is
   where any client applications are to be started, including a Window
   Manager (see below). These could just have as easily been started
   here if we had wanted to. If an Xclients file can't be found, then a
   Window Manager is started for us. Either fvwm, if available, or
   XFree86's minimalist twm if not. If for some reason, neither of these
   can be started, the script would exit, and X would fail to start.

3.1.3. Xclients

   Everything up to this point has followed pretty much a standard and
   predictable sequence of events. To summarize, we have invoked startx,
   which in turn invoked xinit, which has parsed xinitrc for initial
   settings. Most Linuxes should follow this same sequence, though the
   various values and settings may differ.

   We now are at the last link in the chain where the user normally
   would specify his or her preferences, including the Window Manager
   and/or desktop environment to be used. The system will provide sane,
   though possibly uninteresting, defaults if the user has not done so.
   Presumably, this is why you are here ;-)

   The Window Manager, or desktop environment, is typically the last
   application started. If you want other programs (like xterm) started,
   they should be started before the Window Manager and "backgrounded"
   with an "&". This can all be done in the user's ~/.xinitrc. Or as in
   the above example, the actual applications are started from yet
   another script. Let's look at one short, hypothetical such script,

# ~/.Xclients, start my programs.

xset s off s noblank
xset m 30/10 4
xset r rate 200 40

xscreensaver &
rxvt -geometry 80x50-50+150 &

echo Starting Window Manager...

if [ -x /usr/X11R6/bin/wmaker ]; then
  echo `date`: Trying /usr/X11R6/bin/wmaker... |tee -a ~/.wm-errors 2>&1
  exec /usr/X11R6/bin/wmaker >> ~/.wm-errors 2>&1

echo `date`: Failed, trying fvwm... |tee -a ~/.wm-errors 2>&1

# let's try regular fvwm (AnotherLevel doesn't work with fvwm1).
if [ -n "$(type -path fvwm)" ]; then
  # if this works, we stop here
  exec fvwm >> ~/.wm-errors 2>&1

echo `date`: Failed, trying twm... |tee -a ~/.wm-errors 2>&1

# wow, fvwm isn't here either ...
# use twm as a last resort.
exec twm >> ~/.wm-errors 2>&1

# Dead in the water here, X will exit as well, sigh...
echo `date`: Unable to start a Window Manager ... |tee -a ~/.wm-errors 2>&1

# eof

   This really isn't so different than what xinitrc was doing at all. We
   added a few wrinkles, including starting a screen saver, a different
   terminal emulator that this user prefers (rxvt), with even more
   setting up of the environment (monitor, mouse and keyboard) using
   xset this time, and a different Window Manager than was available
   with the system defaults. This is in the user's home directory, so it
   will not be overwritten during upgrades too.

   Actually, X has already started at this point, and we are just
   putting the finishing touches on the configuration. Notice the Window
   Managers are not "backgrounded" with "&" here. This is important!
   Something has to run in the foreground, or X will exit. We didn't
   start a desktop environment in this example, like KDE or GNOME, but
   if we did, this final application would have to be gnome-session or
   startkde instead. Since we are rolling our own here, if we wanted to
   change Window Managers, all we have to do is edit this file, and
   restart X. Vendor supplied configurations may be more complex than
   this, but the same principles apply.

   As an afterword, do not think that any initial client applications
   must be started as we've done here. This is how it has been
   traditionally done, and some may prefer this approach. Most window
   managers have their own built-in ways to start initial programs, as
   do KDE and GNOME. See the respective documentation.

3.2. Display Managers

   The other, more common, approach is the "GUI log-in", where X is
   running before log-in. This is done with the help of a "display
   manager", of which there are various implementations. XFree86
   includes xdm (X Display Manager) for this purpose, though your
   distribution may use one of the others such as gdm (GNOME) or kdm

   Display managers really do much more than enable GUI style log-ins.
   They are also used to manage local as well as remote "displays" on a
   network. We shall not get into details on this here, but it is nicely
   covered in the Remote X Apps Mini HOWTO and the XDMCP HOWTO (see the
   links section). For our purposes here, they provide similar services
   to getty and login, which allow users to log into a system and start
   their default shell, but in a GUI environment.

   Here is an example of a more advanced usage of what else a display
   manager might be used for, from Diego Zamboni:

     I have two X sessions running with different resolutions. I switch
     between them depending on whether my laptop is connected to an
     external monitor or using its own LCD display.

     Here's my /usr/lib/X11/xdm/Xservers file that initiates both

 :1 local /usr/X11R6/bin/X :1 -layout 1024x768
 :0 local /usr/X11R6/bin/X :0 -layout 1600x1200

     Then I have "1024x768" and "1600x1200" defined as "server layouts"
     in my /etc/X11/XF86Config-4, as follows:

 Section "ServerLayout"
         Identifier     "1600x1200"
         Screen         "Screen0" 0 0
         InputDevice    "Mouse0" "CorePointer"
         InputDevice    "Keyboard0" "CoreKeyboard"

 Section "ServerLayout"
         Identifier     "1024x768"
         Screen         "Screen1" 0 0
         InputDevice    "Mouse0" "CorePointer"
         InputDevice    "Keyboard0" "CoreKeyboard"

 ## snip ...

 Section "Screen"
         Identifier   "Screen0"
         Device       "S3 Savage/MX"
         Monitor      "Monitor0"
         DefaultDepth 16

         Subsection "Display"
                 Depth  16
                 Modes  "1600x1200" "1280x1024" "1024x768"

 Section "Screen"
         Identifier   "Screen1"
         Device       "S3 Savage/MX"
         Monitor      "Monitor0"
         DefaultDepth 16

         Subsection "Display"
                 Depth  16
                 Modes  "1024x768" "800x600"

   Note the use of "Identifiers" here. Diego is starting two separate
   "displays" here. Then he can choose which one he wants when he logs

   Most display managers are derived from XFree86's venerable xdm, and
   add their own enhancements. Let's look at the most popular ones

3.2.1. xdm

   xdm can be configured with configuration files located in
   /etc/X11/xdm/, /usr/X11R6/lib/X11/xdm, or similar locations depending
   on your system. These are system wide files. The file xdm-config is
   the main configuration file, and mostly describes where to find
   secondary configuration files:

 ! $XConsortium: xdm-conf.cpp /main/3 1996/01/15 15:17:26 gildea $
 DisplayManager.errorLogFile:   /var/log/xdm-errors
 DisplayManager.servers:                /etc/X11/xdm/Xservers
 DisplayManager.accessFile:     /etc/X11/xdm/Xaccess
 ! All displays should use authorization, but we cannot be sure
 ! X terminals will be configured that way, so by default
 ! use authorization only for local displays :0, :1, etc.
 DisplayManager._0.authorize:   true
 DisplayManager._1.authorize:   true
 ! The following three resources set up display :0 as the console.
 DisplayManager._0.setup:       /etc/X11/xdm/Xsetup_0
 DisplayManager._0.startup:     /etc/X11/xdm/GiveConsole
 DisplayManager._0.reset:       /etc/X11/xdm/TakeConsole
 DisplayManager*resources:      /etc/X11/xdm/Xresources
 DisplayManager*session:                /etc/X11/xdm/Xsession
 ! SECURITY: do not listen for XDMCP or Chooser requests
 ! Comment out this line if you want to manage X terminals with xdm
 DisplayManager.requestPort:    0

   The "!" denotes comments. The command that starts the X server is in
   /etc/X11/xdm/Xservers in this particular example as defined by
   "DisplayManager.servers", and is the equivalent to xserverrc that was
   used for startx X server start up commands, but the syntax is
   slightly different here. The contents of /etc/X11/xdm/Xservers on my
   system are simply:

 :0 local /usr/X11R6/bin/X

   This starts X on the first local display (designated by 0). Any
   special command line arguments that you want to add go here at the

   Below is a sample /etc/X11/xdm/Xsetup_0 which is used to configure
   the log-in screen only. Notice that we're using a shell script here,
   and it's calling xv (a graphics display program) to set the
   background to a nice image (instead of the boring black and white
   background pattern), and if that fails, xsetroot is then invoked to
   at least try to set the background to a nicer blue color. This does
   not configure the login widget itself -- just other things that might
   be wanted on the screen during login.

 xconsole -geometry 480x100-0-0 -daemon -notify -verbose -fn \
   '-schumacher-clean-medium-r-*-*-10-*-*-*-*-*-*-*' -exitOnFail  &

 /usr/X11R6/bin/xv -quit -root /usr/share/pixmaps/Backgrounds/InDreams.jpg \
   || xsetroot -solid darkblue

   /etc/X11/xdm/Xresources controls the X "resources" used during log
   in. In this context, "resources" are user preferences for such items
   as fonts and colors (described in more detail below). Below is a
   snippet that sets up fonts for the log-in widget:

 #if WIDTH > 800
 xlogin*greetFont: -adobe-helvetica-bold-o-normal--24-240-75-75-p-138-iso8859-
 xlogin*font: -adobe-helvetica-medium-r-normal--18-180-75-75-p-103-iso8859-1
 xlogin*promptFont: -adobe-helvetica-bold-r-normal--18-180-75-75-p-103-iso8859
 xlogin*failFont: -adobe-helvetica-bold-r-normal--18-180-75-75-p-103-iso8859-1
 xlogin*greetFont: -adobe-helvetica-bold-o-normal--17-120-100-100-p-92-iso8859
 xlogin*font: -adobe-helvetica-medium-r-normal--12-120-75-75-p-69-iso8859-1
 xlogin*promptFont: -adobe-helvetica-bold-r-normal--12-120-75-75-p-69-iso8859-
 xlogin*failFont: -adobe-helvetica-bold-o-normal--14-140-75-75-p-82-iso8859-1

   As you can see this is using helvetica as the preferred font, with
   different point sizes and dots per inch depending on the screen size.
   This is customizable to suit individual needs. (See below for more on
   understanding X font naming conventions.) Various other aspects can
   similarly be configured.

   /etc/X11/xdm/Xsession is the rough equivalent to xinitrc for startx.
   It will similarly set up a default environment for keyboard, etc. And
   can also start either KDE or GNOME, and other X client programs. This
   is the system wide configuration file. It should also check the
   user's home directory for ~/.xsession, and possibly ~/.Xclients,
   which would contain the user's preferred environment and start up
   programs, just as ~/.xinitrc did with startx. Again, the files in a
   user's home directory may be created or modified by the user any time
   and must be executable shell scripts.

   We shall not include an ~/.xsession example here, since it would be
   very similar to the ~/.xinitrc and ~/.Xclients examples above.

   We've looked only briefly at the main xdm configuration files. Be
   sure to read the man page, and look at what is installed locally, for
   more information. Let's look now at gdm and kdm. We'll just highlight
   significant differences, since they essentially provide the same

3.2.2. gdm

   gdm is the default display manager for GNOME. gdm was written from
   scratch, but functions similarly to xdm. The main configuration file
   is gdm.conf, typically located as /etc/X11/gdm/gdm.conf. This is
   quite different looking than xdm-config. Comments are denoted with a
   "#", and the file has sections, with section headers enclosed in
   square brackets. The command to start X is in the "[servers]"


   Notice this has potentially two displays set up, but the second one
   is commented out. Add any additional X startup options here, e.g.
   "-dpi 100". The log-in screen and log-in widget are configured in the
   "[greeter]" section.

   Start up clients and programs are determined by the "SessionDir"
   statement in the "[daemon]" section. On my installation, this points
   to /etc/X11/gdm/Sessions/, which contains several short scripts. If I
   look at my Default script, it actually executes
   /etc/X11/xdm/Xsession, which in turn would execute ~/.xsession, if
   present. So at this final stage, gdm acts very much like xdm.

   GNOME includes the gdmconfig utility to control many aspects of gdm

3.2.3. kdm

   kdm is the display manager from KDE. The main configuration file for
   kdm is kdmrc and is typically installed as /etc/kde/kdm/kdmrc. As is
   the case with gdm.conf, kdmrc uses "#" for comments, and has sections
   with section headers in similar square brackets. kdm configuration
   can also be edited with the kcontrol utility.

   The visible desktop is configured in the "[Desktop*]" section(s), and
   by the "Setup" directive which should point to a file like
   /usr/share/config/kdm/Xsetup or /etc/X11/xdm/Xsetup_0. This will
   accomplish the same thing as xdm's Xsetup_0 does: namely running any
   programs the user might want such as xconsole.

   The command to launch the X server is the "Xservers" directive in the
   "[General]". Again, this should point to a file such as
   /etc/X11/xdm/Xservers, and uses the same syntax as xdm:

 :0 local /usr/X11R6/bin/X

   Any command line options for the X server, go here.

   The login widget itself is configured in the "[X-*-Greeter]"
   section(s). Compiled in defaults are used if the user does not
   specify any.

   KDE includes the kdmdesktop utility to control some aspects of kdm
   behavior, mostly just the login background.

4. More X Configuration

   Before taking a look at various configuration mechanisms for X
   servers and clients, it should be noted that the advent of Desktop
   Environments like KDE have become popular in part because they can
   control much of the user interaction configuration themselves with
   nice, "user friendly" GUI controls. And in fact, the compliant
   applications that are part of the respective Desktops will be best
   configured through the Desktop's configuration tools, or the
   application's own GUI configuration methods. So, for instance, gtop,
   a GNOME client application, is best configured via GNOME or gtop's
   own menus. But this is not true of all X applications.

4.1. X Resources

   The X server can store various configuration values for client
   programs so they are readily available when needed. If the
   application supports this, it will use these as defaults whenever
   that program is invoked. These are known as "Resources", and are
   often used to define user preferences on a per application basis for
   fonts, colors, screen placement (geometry) and various other
   attributes. This makes it easy to customize applications.

   Resources are specified as text strings (e.g.
   Netscape*blinkingEnabled: False) that can be read from disk in
   various places when X is starting, or even interactively defined on
   the command line. Program components are named in a hierarchical
   fashion, with each object in the hierarchy identified by a class as
   well as an instance name. At the top level of the hierarchy is the
   class and instance name of the application itself. Typically, the
   class name of the application is the same as the program name, but
   with the first letter capitalized (e.g. Vim or Emacs) although some
   programs that begin with the letter "X" also capitalize the second
   letter for historical reasons (e.g. XTerm). Each definition will
   specify a class (or instance), with corresponding resource and value.
   Below this in the hierarchy are the various attributes that make up
   the definable aspects of the application.

   Traditionally, most X programs were configured this way. This is not
   as true today with the advent of Desktop Environments which often
   have their own configuration mechanisms.

   As an example, say we prefer to run xterm with a blue background. So
   if we run it from the command line, we would run it as:

 xterm -bg blue &

   If this is our preference, it would be easier to put this preference
   in a file somewhere, and have the system use our preference. That way
   whenever we started xterm, it would use our preferred value, and we
   wouldn't need the command line options (unless as an override).

   The basic X resource syntax is expressed like:


   Which, in real life, typically looks something like:

 xterm*fontMenu*background: darkblue

   It should be obvious what this does. The use of "*" in the
   definition, is called a "loose binding" and acts as a wild-card.
   Meaning there may be gaps in the widget hierarchy. For instance:

 xterm*background: darkblue

   This would also give a dark blue background for the xterm fontMenu,
   but also any other xterm properties that also have a "background"
   attribute (e.g. window background, etc), no matter where they may be
   in the widget hierarchy. Similarly:

 *background: darkblue

   This would define the background for any and all programs that
   support it -- not just xterm. Using a "." in place of a "*" would be
   more precise, and will not allow for wild-card gaps in the hierarchy.
   Also, the application must support the particular widget attribute.
   "Background" is a fairly safe bet, but many applications will have
   more specialized resources that are not so obvious. It is best to
   check local documentation (man pages, etc), or see if an application
   has an included examples. For instance, Netscape generally comes with
   an file that has an extensive set of resource definitions
   that can be customized.

   X resources are typically stored in more than one place (see below)
   and are processed by the xrdb command (see man page).

4.1.1. App Defaults

   One way of storing preferred application resources is via files named
   for the application in an "app-defaults" directory. For instance, on
   my system, these are in /usr/X11R6/lib/X11/app-defaults/, though this
   may vary according to options your vendor has chosen. This directory
   contains a number of files for such well known X applications as
   xterm, xclock, xcalc, xload, and so on. All in all, it is a
   relatively small number of applications in the overall scheme of
   things. So not all applications use this scheme. In fact, most do

   Each file will contain resource definitions for that application. The
   X server loads these by itself during start up. A brief example from

 ! $XFree86$

 #include "XTerm"

 *VT100*colorMode: on
 *VT100*dynamicColors: on

 ! Uncomment this use color for underline attribute
 !*VT100*colorULMode: on
 !*VT100*underLine: off

 ! Uncomment this to use color for the bold attribute
 !*VT100*colorBDMode: on

 *VT100*color0: black
 *VT100*color1: red3
 *VT100*color2: green3
 *VT100*color3: yellow3
 *VT100*color4: blue3
 *VT100*color5: magenta3
 *VT100*color6: cyan3
 *VT100*color7: gray90
 *VT100*color8: gray30
 *VT100*color9: red
 *VT100*color10: green
 *VT100*color11: yellow
 *VT100*color12: blue
 *VT100*color13: magenta
 *VT100*color14: cyan
 *VT100*color15: white
 *VT100*colorUL: yellow
 *VT100*colorBD: white

   This is mostly various color definitions. The application classname
   is not explicitly stated, and is assumed from the filename. So think
   of each line as starting: XTerm-color*. Also, notice at the top, the
   #include "XTerm" line, which "includes" the resource definitions for
   XTerm, a much longer file with a more diverse set of definitions.
   (Not included due to length, but worth looking at.) These files
   provide system wide defaults, and generally speaking, would not
   normally be edited by the user.

4.1.2. Xdefaults

   Another common method of reading in resource preferences, is with an
   Xdefaults file. Or, sometimes the naming scheme may be Xresources
   instead. This may exist as a system wide file, such as
   /etc/X11/Xresources. Of course, the user is free to create a personal
   version in his home directory, e.g. ~/.Xdefaults. The user's version
   will over-ride any system wide settings, and will remain after system
   upgrades. Obviously, this is the place to put your own preferences.

   Xresources files are read into the resource database with the xrdb
   command. Example:

 xrdb -merge ~/.Xresources

   This can be done interactively at the command line, or placed in a
   script and run automatically as the X session is started. In the case
   of system wide files, this should be taken care of by the vendor
   supplied start up scripts. Generally, such scripts will also check
   the user's home directory as well (see the xinitrc example above). So
   probably all that need be done, is to create the file with a text

   Here's an example to illustrate a very few of the many things that
   might be done with an .Xdefaults file:

 ! This is a comment ;-)

 #ifdef COLOR
 *customization: -color

 !! Let's cast a wide net, for any app supporting these
 ! Blink instead of beeping
 *visualBell: True
 *scrollTtyOutput: False
 *scrollKey:       True

 ! See for many settable resources
 Netscape*noAboutSplash:        True
 Netscape*documentFonts.sizeIncrement: 5
 Netscape*documentFonts.xResolution*iso-8859-1: 120
 Netscape*documentFonts.yResolution*iso-8859-1: 120
 netscape-navigator*geometry: 960x820+240+140

 emacs*Background: DarkBlue
 emacs*Foreground: Wheat
 emacs*pointerColor: Orchid
 emacs*cursorColor: Orchid
 emacs*bitmapIcon: on
 emacs*font: 10x20

 ! GVim colors, etc
 !! GTK versions of gvim will not use all these.
 Vim*useSchemes:         all
 Vim*sgiMode:            true
 Vim*useEnhancedFSB:     true
 Vim.foreground:         Black
 !Vim.background:        lightyellow2
 Vim*background:         white
 ! geometry: width x height
 Vim.geometry:  88x40
 Vim*font:  -misc-fixed-medium-r-normal--20-200-75-75-c-100-iso8859-15-*5
 Vim*menuBackground: yellow
 Vim*menuForeground: black

 rxvt*backspacekey: ^?
 rxvt*background: Black
 rxvt*foreground: wheat
 rxvt*cursorColor: Orchid
 rxvt*geometry: 100x18+40+300
 rxvt*title: Linux
 rxvt*reverseVideo: false
 !rxvt*backgroundPixmap: ~/penguinitis.xpm
 rxvt*scrollBar: true
 rxvt*reverseWrap: true
 rxvt*font: -*-lucidatypewriter-medium-*-*-*-14-*-*-*-*-*-*-*
 rxvt*fullCursor: true
 rxvt*saveLines:  1500
 rxvt*menu: ~/

 XTerm*saveLines:    1500
 ! Do not clear the screen after the program exits
 XTerm*VT100*titeInhibit: true

 ! Fix up xterm's keybindings
 xterm*VT100.translations:      #override \
       <Key>BackSpace:    string(0x7F) \n\
       <Key>Insert:       string(0x1b) string("[2~")\n\
       <Key>Delete:       string(0x1b) string("[3~")\n\
       <Key>Home:         string(0x1b) string("[1~")\n\
       <Key>End:             string(0x1b) string("[4~")\n\
       <Key>Page_Up:      string(0x1b) string("[5~")\n\
       <Key>Page_Down:    string(0x1b) string("[6~")\n\
       <KeyPress>Prior : scroll-back(1,page)\n\
       <KeyPress>Next : scroll-forw(1,page)

 ! Ghostview
 Ghostview*Font: *-helvetica-bold-r-normal--12-*-*-*-*-*-*
 Ghostview*BorderColor:  white
 Ghostview*Text*Font:    rk14
 Ghostview*Background:   #d9d9d9
 !Ghostview*Foreground:  white white black white black

 ! xscreensaver !
 ! Time out after 12 minutes, cycle mode after each 2
 xscreensaver.timeout: 12
 xscreensaver.cycle: 5
 ! Run low priority, and fade between modes
 xscreensaver.nice: 12
 xscreensaver.fadeSeconds: 2 False

   Hopefully, these few examples will give you some ideas to build on. X
   does not need to be restarted if xrdb is used interactively from the
   command line after making changes. The effects are immediate.

   Resources are sometimes available also as command line options. See
   below. Command line options will over-ride any existing resource

4.2. xmodmap, the Keyboard and Mice

   The keyboard and mouse, as well as other possible input devices, are
   defined in XF86Config (or XF86Config-4). There is a keyboard layout
   that is defined based on the preferred language:

 Section "InputDevice"
        Identifier  "Keyboard0"
        Driver      "keyboard"
        Option      "XkbLayout" "us"

   This gives us our default keyboard layout. Valid layout labels are
   listed in /usr/X11R6/lib/X11/xkb/symbols. Also, the setxkbmap utility
   can be used to change this interactively.

   X is highly customizable, and we can modify the keyboard and mouse
   pointer mappings to suit our own preferences. The utility to do this
   is xmodmap (see man page). You don't like where the capslock key is?
   So move it ;-)

   Like xrdb, xmodmap can be run from the command line. Or, preferred
   settings can be stored in a file. Typically this is ~/.Xmodmap, or
   similar. If your X start up files don't parse this, then edit as
   appropriate so that they do (probably from ~/.xinitrc or

   You can view your current key and mouse mappings with: xmodmap -pk
   -pp |less. This will print out all active "keycode" values, with
   corresponding "keysym" values, and any keysym names that xmodmap
   knows about (e.g. "BackSpace"). And should also give you an idea of
   how xmodmap understands key and mouse events. There are two keysyms
   per keycode. The second is the shifted value. XFree86's xev utility
   can be used to dump a lot of information on key-presses and mouse
   events interactively. Pay attention to the "keycode" value. That is
   what you will need to know in order to re-map.

   xmodmap is often used to make minor keyboard adjustments, like proper
   Backspace/Delete mapping. Or can be used make major adjustments such
   as for international mappings. You can only re-map keys and mouse
   events -- you cannot assign macros to key events (your Window Manager
   or Desktop might have some of this functionality).

   A nice discussion of setting up international keyboards . Also,
   [] Google search will turn up many creative

   The man page has many brief examples of various usages. Here is what
   an one hypothetical ~/.Xmodmap might look like:

 ! /home/hal/.Xmodmap, last change 10/03/01
 ! Force backspace to 22 and Delete to 111
 keycode 22 = BackSpace
 keycode 111 = Delete
 ! My keyboard handles right and left Alt differently. Make the
 ! Right act like the Left to avoid digital gymnastics.
 keycode 63 = Alt_L
 keycode 113 = Meta_L
 ! Hard-code the keypad to numeric values as if numlock is always on
 ! since I never use it for anything else.
 keycode 79=7
 keycode 80=8
 keycode 81=9
 keycode 83=4
 keycode 84=5
 keycode 85=6
 keycode 87=1
 keycode 88=2
 keycode 89=3
 keycode 90=0
 keycode 91=period
 keycode 86 = plus
 ! deactivate Num_Lock key since we don't need it now.
 keycode 77 =
 ! My capslock is next to tab. I hit it by mistake sometimes,
 ! and don't use it anyway. So make capslock act like Tab.
 keycode 66 = Tab
 clear lock
 ! Reverse mouse buttons for left-handed people
 pointer = 3 2 1

   As with many XFree86 files, the "!" represents a comment. Another
   possible use, is to redefine those annoying "Windows" keys to
   something useful. Hopefully this gives an idea of some things one
   might want to do to make the keyboard more agreeable to us.

   Speaking of the Numlock key, X will typically disable this when it
   starts up. No matter how you have the BIOS set up, or Linux set up
   before X starts. So the trick above is one way. There is also a
   utility available as either numlockx, or setnumlock, that can be
   found on the �Net, if your distribution does not include one or the
   other. This can be put in a start up file to turn Numlock on
   automatically if you would prefer.

   Window Managers and Desktop Environments will also allow
   customization of the keyboard and mouse (as long as it is recognized
   correctly by X). This may be an easier way to configure certain

4.2.1. Special Key Mappings

   There are several special key mappings traditionally used in XFree86.

          Will kill the X server process in an orderly fashion. This is
          a quick, easy, legitimate way to restart X. Note it does not
          restart the display manager (if used) -- just X itself.

          where n corresponds to a valid TTY number (typically 1-6).
          This is typically used to jump to a text console login, while
          X remains running. To get back to X, press Alt-Fn. In this
          case, n represents one plus the last TTY (e.g. Alt-F7 if there
          are six available TTY's).

   Ctrl-Alt-+ and Ctrl-Alt--
          That is the plus and minus keys on the keypad. This will cycle
          through any existing valid screen resolution modes, e.g.
          1024�768 -> 600�800. Note the actual screen size is the same
          -- just the view and resolution changes. Not all that useful
          for most purposes. You cannot permanently change the screen
          resolution without restarting X.

   It's possible your Window Manager, Desktop Environment or other
   system component may trap these, and alter the standard behavior. In
   addition, the Ctrl-Alt-Delete may be trapped as well. This should
   shut X (and the system) down orderly, if it is available.

4.2.2. Mice and Pointers

   As mentioned, Linux and Unix make heavy use of three mouse buttons.
   If a mouse only has two buttons, then the third (i.e. the middle)
   button can be simulated by pressing both buttons simultaneously. This
   is a configuration option set in XF86Config as the "Emulate3Buttons"

 Section "InputDevice"
        Identifier  "Mouse0"
        Driver      "mouse"
        Option      "Device" "/dev/mouse"
        Option      "Protocol" "PS/2"
        Option      "Emulate3Buttons" "on"

   When all is said and done, a third button is quite handy and I would
   personally recommend having one. On wheeled mice, the "wheel" acts as
   the third button, if pressed. Many standard wheel mice seem to work
   with the "IMPS/2" protocol option.

   Specifically, the third button (middle) is the "paste" button in
   virtually all Linux applications. Copy and paste works a little
   different in Linux. The left button is the copy button. Just hold it
   down, and drag over text. It is automatically copied to the X
   "clipboard". Then, the middle button will paste from there. A very
   simple process. A double-click should copy individual words, and a
   triple-click individual lines of text. If for some reason, this does
   not work, it is either a poorly implemented application, or a bug of
   some kind. Some older versions of Netscape were not consistent about
   this, for instance. To paste from the keyboard, this should be

   "Drag and Drop" is not natively supported by X itself. But, is
   implemented by some toolkits and Desktop Environments. One should not
   expect this to work with non-compliant applications (i.e non-KDE
   aware applications in KDE for example).

4.3. xset

   xset is yet another XFree86 utility to set user preferences. xset is
   a bit of a catch-all and is used to change various, unrelated X
   server settings. Mostly this is a command line way of configuring
   some of the same things that are defined in XF86Config (but not

   Common usages of xset are to set DPMS on or off and preferred
   intervals, to dynamically change the FontPath or re-read it, to
   control keyboard LEDs, to adjust mouse (or other pointer) movement
   speed, set keyboard "autorepeat" and "repeat" rates, and to control
   X's built in screen blanking. See the man page, of course, for
   detailed explanations, and other xset usages.

   Again, xset can be used interactively from the command line. But most
   often preferred settings are stored in one of the start up
   configuration files, like .xinitrc or .xsession. A very brief

 # Turn off screen blanking
 xset s off

 # Enable DPMS energy saving
 xset +dpms

 # Tweak the rodent
 xset m 30/10 4

 # Speed up keyboard
 xset r rate 200 40

   Your desktop may have a GUI front-end for xset.

5. Fonts and Colors

   Understanding fonts and colors can be more complex in X than on other

5.1. Fonts Demystified

   X knows about various font types, including bitmaps, Type 1, and as
   of v4.x, TrueType. The X server can either handle fonts itself, or
   sometimes this duty is forked to a font server (of which there are
   several). xfs (X Font Server) is the most common font server in use
   on Linux.

   A font server is not required, as X can handle most font rendering
   itself. Font servers are traditionally used for serving fonts to
   multiple hosts on a network, but sometimes are also used to provide
   enhanced functionality. Additionally, a font server may provide a
   modest performance boost by off-loading font rendering to a separate

   X knows about fonts according to fonts that are in the "FontPath".
   This is set initially in XF86Config. If the X server is handling font
   duties itself (i.e. no font server), this will be a list of
   directories that contain font files, like:

 FontPath        "/usr/X11R6/lib/X11/fonts/misc:unscaled"
 FontPath        "/usr/X11R6/lib/X11/fonts/100dpi:unscaled"
 FontPath        "/usr/X11R6/lib/X11/fonts/75dpi:unscaled"
 FontPath        "/usr/X11R6/lib/X11/fonts/Type1"
 FontPath        "/usr/X11R6/lib/X11/fonts/misc"
 FontPath        "/usr/X11R6/lib/X11/fonts/100dpi"
 FontPath        "/usr/X11R6/lib/X11/fonts/75dpi"

   If a font server is being used, the "FontPath" will point to the
   socket where the font server is serving (this is just one possible

 FontPath "unix/:7101"

   In this latter case, the actual font directories that are available
   will be configured with the font server (see local documentation),
   which will use a similar directory type scheme as shown for

   Once suitable fonts have been installed, they must be "prepared". For
   most fonts, this means running the mkfontdir utility (see man page)
   in the directory where the fonts are (as root). Type 1 and TrueType
   require additional steps (see below). Your vendor has done this for
   any fonts that were included with your distribution. So, this will
   only need to be done for fonts that you add. For newly added fonts to
   become visible to X, you will need to run the appropriate xset
   commands to either modify the existing FontPath, or re-read it (see
   man page). Or, re-initialize your font server.

   Example: Preparing fonts, and re-initializing font server after
   adding new fonts:

 mkfontdir /usr/X11R6/lib/X11/fonts/my_new_fonts/
 /etc/init.d/xfs restart

   The first command may not be necessary on newer distros (since it's
   done by the init script in some cases). And the font server
   configuration would need to be modified, if this is a new directory.
   Example: re-initializing with no font server:

 mkfontdir /usr/X11R6/lib/X11/fonts/my_new_fonts/
 xset +fp /usr/X11R6/lib/X11/fonts/my_new_fonts/
 xset fp rehash

   The "xset +fp" would not be necessary if the directory is already
   part of the FontPath.

   xlsfonts | less can be used to list what fonts are known, and thus
   available, to X and its clients. Run xlsfonts | less, and you also
   can get an idea of the font definition as understood by X. Font
   resources are specified quite explicitly, and it may seem complex at
   first. The X Logical Font Description ("XLFD") is the full
   description for any given font. The XLFD looks like:


   Where each field, left to right is:

   fndry - font foundry, the company or individual which made the font.

   fmly - font family, the popular nickname of the font

   wght - font weight (bold, medium, etc.)

   slant - font slant (italics, oblique, roman (normal), etc.)

   sWdth - font width (normal, condensed, extended, etc.)

   adstyl - additional style (sans serif, serif, etc.)

   pxlsz - pixel size, the number of pixels vertically in a character

   ptSz - approximate point size of the text (similar to pxlsz)

   resx - horizontal resolution, in dpi

   resy - vertical resolution, in dpi

   spc - spacing, only useful, apparently, in the Schumacher fonts

   avgWidth - average character width of the font

   rgstry - the recognized registry that lists the font

   encdng - nationality encoding

   The "*" acts as a wild-card character. In fact, if not every field is
   specified, the X server will take the first match it finds in the
   FontPath. This is why it is best to order the FontPath with preferred
   fonts coming first since some programs will deliberately specify
   fonts "loosely" so that your system has some discretion.

   The program xfontsel (X Font Selector) may be useful. Try launching
   it now. You will see nothing helpful in the main window at first, but
   try holding the left button down on the fndry button. If all your
   fonts are in order, you will see a menu of selections such as adobe
   and b&h and bitstream and so forth. Select one such as b&h and you
   will notice that the font in the lower window changes to something
   intelligible. This is the way fonts are selected with this program;
   starting from the left, which is the most general selection, and
   moving toward the right, to the more specific options. Selecting an
   option toward the rightmost end will not make much sense before the
   foundry, for instance, is selected, because the options are generally
   ordered by their dependence on each other.

   When you select from the fmly selection, you will see most of the
   options grayed out, and only three remaining. That means that these
   three are the only families of font made by this foundry. Some
   families appear under more than one foundry, for instance, both Adobe
   and Bitstream make a variation of the Courier font. Now you can
   select the wght, and so forth. After you get far enough you will have
   narrowed it down to the font that you want. You don't necessarily
   have to fill in all the options to choose a single font, there's not
   that many fonts on your system! The options that you do not select
   will be represented by a * indicating that any option will do in that
   spot, and gives X some leeway.

   When you are satisfied with your font selection, hit the select
   button, and your selection will be placed in the X clipboard, ready
   to be pasted into your document or whatever you are working on. For
   example, open an xterm window and type in something like xterm -font
   followed by an opening quotation mark. Then point to that spot on
   your screen, and click your middle mouse button (or click both the
   left and right, if you are middle-button impaired). This will paste
   the selection from the clipboard, which should be the font you just
   selected. Then enter the closing quote, and hit Enter. For instance,
   a nice big xterm with a Courier font specified would look like this:
   xterm -font "-adobe-courier-medium-r-*-*-14-*-*-*-*-*-*-*".

   If you've found a font you prefer, this can permanently be used by
   placing the font definition in the appropriate configuration file
   (see above).

   Note that you can also limit the number of fonts that you want
   xfontsel to display with the command line option -pattern, followed
   by a quoted font specification, as discussed above.

   The xfd utility is also helpful for examining individual fonts. If
   launched with a command line such as xfd -fn fixed, it will show you
   the complete character set for that font.

   KDE and GNOME have their own utilities that are not quite as obtuse

5.1.1. Type 1 and TrueType Fonts

   The fonts provided with XFree86 are of limited use for many of us,
   considering that about the only place you'll find fonts of that kind,
   are used in the X Window System itself for the most part.
   Unfortunately many media junkies, web designers and fontaholics work
   in operating systems that rely on other formats. And then, there
   often does not seem to be much emphasis by some distributions on
   making the best of the default fonts either.

   Type 1 fonts, most commonly used in conjunction with PostScript
   document formats, are the traditional standard in Unix and Linux
   environments. You should have a reasonably good starter selection
   installed already. Or, more can be found for free on the Internet
   with considerable ease, and Try [] for starters. Type 1 are scalable
   fonts, and have many of the same benefits of the better known
   TrueType fonts. If you don't have a good selection of TrueType fonts
   installed, then Type 1 is what you want for most GUI applications.
   But again, this is not standard on other platforms, and can present
   problems when viewing documents (e.g. web pages) that are designed
   with "other platforms" in mind.

   TrueType fonts started with Apple, and later were licensed by
   Microsoft. So people migrating from non-Unix platforms are already
   familiar with these high quality fonts. Unfortunately, there are not
   many quality TrueType fonts under a suitable license, and thus there
   are not many included with Linux distributions. And the ones that
   are, often are not as high quality. Also unfortunately, TrueType has
   become somewhat of a standard on the Web and in other venues, and not
   having good TrueType fonts can be a detriment. XFree86 also seems to
   render TrueType a little better than Type1.

   That is the bad news. The good news is that any TrueType font
   included with any version of Windows, or any Windows applications,
   should work on Linux. Though you will have to take some additional
   steps to integrate them. This particularly helps web browsing where
   X's bitmapped fonts just don't scale well.

   We shall not go into detail on installing and configuring these fonts
   here, as it is addressed in depth in other documents. See
   [] The Font HOWTO for general
   font information, and Type 1 tips. See The Font De-Uglification Mini
   HOWTO, The Font De-Uglification Mini HOWTO, for various X related
   font tips, especially TrueType.

5.2. Colors

   Let's go back to our terminal window and try something. Open an xterm
   with a command line like the following:

 xterm -fg DarkSteelBlue1 -bg red3 &

   Ouch! While that may not be pretty, and you may not do much of your
   best work in it, it demonstrates one interesting aspect of X
   configuration -- color names. While not particularly precise, this is
   a nice way to remember a variety of colors. Note that color names are
   never case-sensitive.

   The X server will actually deal with color values as a hexadecimal
   Red-Green-Blue (RGB) color notation. This would look something like
   "#0aff0a" in hex. Not so easy to remember. But X gives a more
   mnemonic way of remembering valid color definitions. These are stored
   in a text table, typically as /usr/X11R6/lib/X11/rgb.txt, and is
   defined in XF86Config in the "Files" section.

   If you are interested, have a look with a text editor. There are
   many, many shades defined. I count eighty-three shades of blue in
   mine, for instance. Brief snip:

 176 226 255             LightSkyBlue1
 164 211 238             LightSkyBlue2
 141 182 205             LightSkyBlue3
  96 123 139             LightSkyBlue4
 202 225 255             LightSteelBlue1
 188 210 238             LightSteelBlue2
 162 181 205             LightSteelBlue3
 110 123 139             LightSteelBlue4
 191 239 255             LightBlue1
 178 223 238             LightBlue2
 154 192 205             LightBlue3
 104 131 139             LightBlue4

   This file can be customized should you desire, but this is rarely
   needed for most of us. It is important to have though, since some
   applications depend on it.

   Desktop Environments will have a GUI utility for selecting colors.

6. Window Managers and Desktops

   We shall not delve into configuring Window Manager's and Desktop
   Environments. There is just too much to try to cover in one document.
   It is important to realize that the two are not the same. There are
   many, many Window Managers available.

6.1. Window Managers

   Window Managers are highly configurable. Many aspects of user
   interaction can be controlled by the Window Manager.

   Some of the most popular Window Managers:

   aewm: []

   AfterStep: []

   BlackBox: []

   Enlightenment: []

   Fluxbox: []

   fvwm: []

   IceWM: []

   olwm (OpenLook Window Manager):

   Sawmill: []

   WindowMaker: []

   XFce: []

   There are many, many lesser known ones as well.
   [] has an
   updated list of Window Managers, and related information. There is
   always [] freshmeat too.

   GNOME and KDE both have their default Window Manager, but support
   other, compliant Window Managers as well. Your distribution probably
   has included at least several. Try them all if you don't already have
   a favorite. Your distribution probably also has a method of switching
   dynamically between Window Managers (and Desktop Environments too).

6.2. Desktop Environments

   Desktop Environments are not really new, but their popularity has
   increased with advent of the two big names: KDE and GNOME. To a
   certain extent, the Desktop Environment functionality overlaps the
   Window Manager's. They both can be responsible for the root window
   background, root window menu, icons, taskbars, etc. Generally
   speaking, if a Desktop Environment is running, it is controlling
   these aspects. That is the main idea behind them -- to integrate the
   various components into a cohesive, consistent whole. Desktop
   Environments also add some interoperability and ease-of-use features
   that a simple Window Manager cannot.

   Oh, another point: Desktop Environments also try to do as much X
   session configuration as possible. Any of their compliant clients
   will more than likely be configured by the Desktop, or have it's own
   configuration that conforms to the Desktop's style. This is at least
   partly to avoid much of the seemingly helter-skelter text file
   configuration we looked at in the above sections, and make life a
   little easier for the user.

   There is a trade-off in this additional functionality, and that is
   that it takes memory and system resources to oversee all this. If you
   have plenty of memory and a fast computer, this is no problem. But in
   low memory situations, this can cause a slowdown (see the performance
   section below). 64M of RAM is probably borderline with either KDE or

   So do you need a Desktop Environment? That is up to the user. They
   are certainly not required to run X, but do add features that many
   users want or expect in a GUI. Which one is better? Ah, but that is
   up to you to decide!

   KDE has been around longer than GNOME, and some would say maybe a
   little more mature. KDE is based on the QT widget toolkit. A quote
   from the [] KDE home page:

     KDE is a powerful Open Source graphical desktop environment for
     Unix workstations. It combines ease of use, contemporary
     functionality, and outstanding graphical design with the
     technological superiority of the Unix operating system.

     KDE is a mature desktop suite providing a solid basis to an ever
     growing number of applications for Unix workstations. KDE has
     developed a high quality development framework for Unix, which
     allows for the rapid and efficient creation of applications.

   GNOME is based on the GTK+ toolkit. And a quote from the
   [] GNOME home page:

     GNOME stands for GNU Network Object Model Environment. The GNOME
     project intends to build a complete, user-friendly desktop based
     entirely on free software. GNOME is part of the GNU project, and
     GNOME is part of the Open Source(tm) movement. The desktop will
     consist of small utilities and larger applications which share a
     consistent look and feel. GNOME uses GTK+ as the GUI toolkit for
     all GNOME-compliant applications.

   XFce is a lighter weight, less featureful Desktop Environment that
   does not get as much attention as the others. XFce is also based on
   the GTK+ toolkit. And a quote from the [] XFce home

     The XFce project was first started because I needed a simple,
     light and efficient environment for my Linux System.

     I believe that the desktop environment should be made to increase
     user productivity. Therefore, the goal is keep most system
     resources for the applications, and not to consume all memory and
     CPU usage with the desktop environment.

   All these have their own extensive documentation. If you can't find
   what you need installed on your system, check the respective home

7. X and the Command Line

   What would a Unix-like operating system be without a command line
   interface? The command line can be useful, and is readily available
   with X. In fact, for many it is an integral part of their X working

   Any X program can be started directly from the command line just by
   typing the program name at a shell prompt in an xterm, or other
   terminal window. Most applications will have a very rich set of
   command line "options", such as background color, font, geometry
   (screen placement), etc, etc. Command line options over-ride compiled
   in defaults, or other system enabled "resources".

   Many traditional X programs will use the same basic names for command
   line options. All applications written using the MIT X Toolkit
   Intrinsics (Xt) (such as those included with XFree86) automatically
   accept the following options. Some non-Xt applications also use
   these, or something similar. For instance, "geometry" is close to a
   universally accepted option.

   -display [host]:display[.screen]
          This option specifies the X server display to use. This is
          often used where applications are run on one system, and
          displayed on another. The application needs to know where to
          display. This is sometimes also accomplished by setting the
          "$DISPLAY" variable, which uses the same syntax.

   -geometry geometry
          The initial size and location of the window, in a format such
          as width x height +horz_offset +vert_offset or +horz_offset
          -vert_offset. Note that if you put in a negative horizontal or
          vertical offset, the window will be placed counting backward
          from the right or the bottom of the screen, respectively,
          instead of from the top left corner.

   -font fontname
          The font to use for displaying the text in your window (see
          font section below).

   -bg color
          The color to use for the window background. Typically this is
          a "color name" (see below).

   -fg color
          The color to use for the window foreground (i.e. fonts, etc).

   -name resource-name
          Useful for specifying the name under which the resources for
          this application will be found (e.g. as specified in
          .Xdefaults). This is useful to distinguish between invocations
          of the same application. For example, two xterms can be
          "named" differently so that they may inherit different
          resources based upon the specified names in the resource

   -title string
          This is the title to be used for the window on your display,
          generally used by the Window Manager to put a descriptive
          title at the top of the window. Not to be confused with the
          "-name" option.

          Open window in an iconified state.

   -xrm resource-string
          This option specifies a resource name and value to override
          any defaults that may already be set (i.e. via .Xresources or
          similar). Also useful for setting X resources that do not have
          explicit command line options. For example, the command line
          "xterm -xrm xterm*background: blue &" is functionally the same
          as "xterm -bg blue &".

   These are the most noteworthy. There are others. Many programs will
   have their own additional options that are application specific. Many
   newer applications today don't necessarily adhere to the Xt
   standards, and will use their own options, or those provided by their
   respective toolkit. If nothing else, man pages are a good reference
   for command syntax, and are your friends here. Or, the application
   will have a "--usage" or "--help" command line switch to list
   available options:

 $ gnome-terminal --usage
 Usage: gnome-terminal [-?] [--disable-sound] [--enable-sound]
   [--espeaker=HOSTNAME:PORT] [--version] [--usage] [--gdk-debug=FLAGS]
   [--gdk-no-debug=FLAGS] [--display=DISPLAY] [--sync] [--no-xshm]
   [--name=NAME] [--class=CLASS] [--gxid_host=HOST] [--gxid_port=PORT]
   [--xim-preedit=STYLE] [--xim-status=STYLE] [--gtk-debug=FLAGS]
   [--gtk-no-debug=FLAGS] [--g-fatal-warnings] [--gtk-module=MODULE]
   [--disable-crash-dialog] [--sm-client-id=ID] [--sm-config-prefix=PREFIX]
   [--sm-disable] [--tclass=TCLASS] [--font=FONT] [--nologin] [--login]
   [--geometry=GEOMETRY] [-e COMMAND] [-x COMMAND] [--foreground=COLOR]
   [--background=COLOR] [--solid] [--pixmap=PIXMAP] [--bgscroll]
   [--bgnoscroll] [--shaded] [--noshaded] [--transparent] [--utmp]
   [--noutmp] [--wtmp] [--nowtmp] [--lastlog] [--nolastlog] [-t TITLE]
   [--icon=ICON] [--termname=TERMNAME] [--start-factory-server]


7.1. xterm and friends

   Sooner or later, most of us need to access the "command line" for one
   reason or another. For some, this might even be a common way of
   working in X. In addition to being able to launch X applications from
   the command prompt, there is also a wealth of programs that run in
   "text mode" for Linux.

   This is possible via "terminal emulators" such as xterm. The closest
   counterpart from Microsoft is the so-called DOS-box, which is child's
   play by comparison. Linux terminals support color, full mouse
   copy/paste (and some wheeled mice), pseudo-transparency and pixmap
   backgrounds, scrollbars, menus and generally a slew of other
   features. While xterm is the best known such terminal emulator, there
   are many similar programs. To name a few: Eterm, rxvt, aterm, konsole
   (KDE) and gnome-terminal.

   In typical usage, when a terminal emulator window is opened, a shell
   is started for the user to interact with. The default for essentially
   all Linuxes, is the bash shell. So when all is said and done, the
   user is interacting with X, the terminal, and the shell all at once.
   Each may have it's own influence. For example, how keystrokes are
   handled since they move from hardware to X server to terminal to the
   shell and finally echoed back to the user.

   Quick and easy terminal configuration is done via the "$TERM"
   variable, which is typically set in one of the user's shell
   configuration files. Or the terminal itself will have a compiled in
   default. The default value for this is most often "xterm":

 $ echo $TERM

   Normally this is sufficient, as your vendor has already set this up
   in a reasonable way. The "$TERM" variable is actually a reference to
   an entry in the "termcap" database (man termcap), which is typically
   installed as /etc/termcap. Unless you are doing something really
   unusual, you probably will not need to change this. Some additional
   terminal configuration can be done with the stty command (see man
   page). Terminal configuration is really beyond the scope of this

   The terminal application itself (e.g. xterm) will also have various
   configuration options. Permanent settings are best stored in a
   ~/.Xdefaults or similar file for those applications that support
   this. Generally speaking, applications with a GUI configuration (such
   as gnome-terminal), will be configured by their own menu driven
   configuration instead.

   Also, you are interacting with the shell too, which can have it's own
   impact, particularly on how keystrokes are handled at the shell
   prompt. For bash, this can be adjusted in ~/.inputrc. Again, this is
   beyond the scope of this document, but check with either local or
   on-line bash (or other shell) references.

   Terminal emulators like xterm require a monospaced font. So forget
   about TrueType or Type 1 fonts.

8. X Networking and Security

   As mentioned, X is essentially a networking protocol with graphical
   displaying capabilities. This makes for some interesting usage
   possibilities. And also means there are inherent security
   considerations, as there is with any networking environment. And if
   you ever connect to the Internet, you are in the midst of one very
   large, hostile network ;-)

   X clients connect to X servers via various networking protocols,
   including TCP/IP. Even with just local connections. Possible usages
   here are to run an application on one computer, and display it on
   another. Or, to actually log in to a remote system, and have it
   display to your local screen, with the client apps using the remote
   system's CPU and RAM.

   Without any precautions, this can leave you wide open to various
   types of mischief and abuse. For instance, anyone logged into to your
   system can access your "display", meaning they can see what you are
   doing if they want to. Thankfully, most recent Linux releases come
   with some default security precautions enabled. But it is best to
   make sure for yourself that you are protected.

   Both X networking and security are nicely covered in The Remote X
   Apps Mini HOWTO , so we shall not need to try to rehash it here.
   Recommended reading. See other references in the Links section of the
   Appendix below.

   A few recommended precautions:

     * Never, ever run X as root. The number of bad things that can
       happen, dramatically increases when logged in as root. Learn to
       run as much as possible as a regular user, and su to root only
       when needed. This may sound like a lot of extra work (and
       probably is at first), but once the "right" way of doing things
       is learned, it soon becomes second nature.
       A brief anecdote from a friend: he had a client who's new system
       stopped "working". Curiously, he found the entire /dev directory
       was missing, which he re-installed and all was well again. He was
       back a few days later and found the system logged in as root to
       X, and someone had clicked on /dev in the file manager, and
       dragged it onto the desktop. Smooth move!
     * If you ever connect to a network with untrusted users, be sure to
       have a firewall between you and them. This goes double for the
       Internet. Firewalling is beyond the scope of this document, but
       is covered in many other places, including your vendor's website.
       [] has several security
       HOWTOs that can help as well. [] is another good place to look.
     * You can disable TCP connections with the "-nolisten tcp" command
       line X server switch. This does not help for local connections
       though. For xinit/startx:

 exec X :0 -dpi 100 -nolisten tcp

       Placed in ~/.xserverrc. And for xdm, in

 :0 local /usr/X11R6/bin/X :0 -nolisten tcp


9. Performance Considerations

   As has been discussed, what we call X, is actually a convergence of
   various components: X server, Window Manager, Desktop, etc. With MS
   Windows, the GUI desktop is tightly integrated with the operating
   system itself. This is not the case in Linux which follows the Unix
   tradition of combining various independent components to achieve some
   end result. So we have choices with each component and it's attendant
   configuration and implementation. In short, much flexibility. This is
   where you come in. You can try various possibilities and decide what
   you gives you the most bang for the buck.

   On low end hardware, this gives us much latitude to decrease the
   demand on available system resources. This is good because, if given
   the opportunity, X can be quite greedy with system resources. If
   you've recently installed a new Linux distribution, you've probably
   been given a default Desktop with many bells and whistles. And
   something that will probably need a fair amount of memory and CPU to
   achieve a reasonable level of performance. If you have the horse
   power, this should not be a problem.

   It is often said that Linux functions very well with relatively
   little memory. This is true to a point. It does not mean though that
   every possible configuration will run with low memory. So if you want
   to use memory hungry applications, then you will have to have the
   memory. Or you will have to make sacrifices to achieve a satisfactory
   level of performance. It is quite possible to run X with reasonable
   performance on 16 Meg of RAM, and even less if you really want to
   push it. But you would have to live with some real limitations.

   Let's look at some of the components and ways to decrease the demand
   on system resources, in case you are at the low end on hardware, or
   performance is not up to expectations.

9.1. Hardware

     * No big surprise, but overall system performance will be best with
       a fast graphics card, a fast hard drive, and lots and lots of
       memory -- if you want both a fast and flashy system.
     * Graphics cards are of course necessary, and the X server's video
       performance is tied to the card's chipset, and the corresponding
       XFree86 driver. Just because a given card is supported by XFree86
       does not necessarily mean it is as well optimized as other cards!
       It may also perform better at a lower color depth (see below). It
       may well be worth the trip to to see if there are any
       notes related to your card with respect to performance or other
     * And you might try other versions of XFree86. At this time v4.2
       was just recently released. Some cards may still perform better
       with 3.3.6 due to the way v4.x is being incrementally developed.
       If you are using x4.x and performance is not good, then make sure
       you are using the latest available version.

9.2. Memory

   The more memory, the better. X will do a lot caching to help
   performance. But caching requires memory, and if there isn't much to
   start with, then we would need to reduce memory requirements. Some
   tips for those with low memory or performance problems:

     * Use the free command to make sure all memory and swap is
     * Make sure you don't have other system services that are hogging
       memory or CPU. Use top or ps to see what is running, and disable
       anything you can to free up memory and CPU. Again, a default
       installation may have many things running that you don't really
     * Make sure you have plenty of swap space. With low, or even
       modest, memory, swap is all the more important. A general rule of
       thumb is twice as much swap as physical memory. With low memory,
       this is not enough. Try four times real memory. Or more. If you
       can't create more swap partitions, see the mkswap man page about
       creating swap files instead. Constant disk churning is a symptom
       of insufficient swap space, and the system will be slowed as a
       result, sometimes drastically. Or, possibly this may be the
       symptom of a poorly behaved kernel VM system (try another kernel
       in this case).
     * Drive performance is important for swap performance. Make sure
       your drive has DMA enabled if the drive supports it, and is
       otherwise tuned and performing up to snuff. See the hdparm man
       page. Slow drive + slow card + low memory = slow system.
     * Don't use KDE or GNOME if memory is tight. These both require
       substantial memory, and are not required to just run X. Think of
       these as usability enhancements. 32M probably may not be enough.
       64M may be decent, depending on what other applications are being
       used, and other variables. 128M should be adequate in most
       situations. 256M or more to be comfortable. File Managers like
       Nautilus and gmc can also be memory hungry.
     * Use a lightweight window manger. WindowMaker, BlackBox, IceWM,
       fvwm (and variants), XFce, all have reputations of performing
       well with low memory. There are surely others as well.
       Experiment. fvwm is generally considered the lightest of the
       A very nice desktop is still very possible even without KDE or
       GNOME. In fact, most KDE and GNOME applications can still be used
       even if KDE and GNOME are not running themselves (assuming the
       right libs are installed).
     * Don't use fancy themes or backgrounds. Plain and simple is easier
       on resources. Use a solid color background. Avoid pixmaps or
       gradients for any kind of background, including menus, title
       bars, etc.
     * Use a lesser screen size and color depth. 800x600x16 will not
       push X as hard and be easier on system resources than higher
       values. While a ColorDepth of 24 is preferred, you probably will
       not notice the difference of 16 with the majority of
     * Some applications require much more memory than others. Some
       notable hogs are Netscape, Mozilla, office suites, and the Gimp.
       Netscape is faster than Mozilla (but not as nice).
       Netscape-Navigator uses less memory than Netscape-Communicator.
       Close any of these apps when not in use. Use text browsers like
       lynx or w3m wherever you can, like reading locally installed HTML
       documentation. Much faster, and much less memory is required.
     * Also, use text based clients for mail (mutt or pine) and news
       (slrn or trn). Again, faster and much less memory is used, and
       these are after all text based protocols at heart anyway.
     * rxvt uses less memory than xterm, konsole or gnome-terminal.
     * If you run an X session for long periods of time (like days or
       weeks), restart X occasionally to free memory tied up as cache.
     * Disable "backing store" and "save-unders" to reduce memory usage
       (performance penalty though). Check your Window Manager's
       settings too. See what modules are being loaded in the "Modules"
       section of XF86Config as well. Your installation may have many
       unnecessary ones enabled, or ones you can't take advantage of
       (e.g. "v4l", aka "Video4Linux").
     * Font servers may provide a slight performance boost by
       off-loading font rendering to the font server, while freeing the
       X server to do other things. But, the font server will use a
       small additional amount of memory as well. So, you can try it
       either way to see if it makes a difference.
     * Lastly, RAM is cheap now. Buy some ;-) A new drive too.
     * RAM is still just too low for X? Check out tinyX:
       [] Reportedly runs
       in as little as 4 Meg of RAM.

9.3. X over the Network

   X is not particularly network friendly. In other words, it is a
   bandwidth hog. This should not be a problem in LAN situations, but
   may be if trying to use X over the Internet.

     * lbxproxy, the low bandwidth X proxy, utilizes various
       optimizations to improve performance in low bandwidth, or high
       latency situations. See the man page.
     * VNC (Virtual Network Computing), has some of the same advantages
       as X for displaying applications on remote systems, but is more
       network friendly. Your Linux installation should have both VNC
       client and server packages available.

9.4. Other Tips

   Other tips to eek out better performance:

     * Use xset to speed up the keyboard. This can make the system feel
       more responsive even if it isn't really. The default always
       seemed sluggish to me.
     * renice X to give it a higher priority. Other platforms give the
       GUI high scheduling priority to achieve better responsiveness.
       But this is at a cost to other processes. Linux is a blank slate.
       You might include the font server (if being used), and key KDE
       and GNOME processes as well.

 nice -n -10 X :0

       This will not do much on systems that are mostly idle.
       This does not work so well with startx since X runs as root, and
       you are not root, right? So you would have to use something like
       sudo to have this done automatically.

10. Appendix

10.1. Terminology and Usage

   There are a few basic concepts and terminologies you should be
   familiar with. These terms will appear here, in the manual pages, and
   in other help files and documentation.

     * The "X server" is the low-level driver software that interacts
       with your video card and other system hardware, and manages the
       "display" and the various components attached to the "display"
       (keyboard, mouse, etc.). And, of course, handles requests from
       clients as well. There are different X servers for different
       X Servers are referenced in the form of:
       An example would look like: my_computer:0.0
       If host (and domain) is omitted, localhost is assumed. "Host" can
       be a remote host. If "screen" is omitted, then "0" (the first
       screen) is assumed. In it's shortest form, the X server is often
       represented as just ":0", which would be the first local
       "display". X supports multiple "displays" and multiple "screens".
       "Screen" and "Display" have special meanings in relation to X
       servers, in addition to their more common usage.
     * When X is invoked, the X server will initialize one or more
       "displays". Yes, X can have more than one "display" available
       (though this is not a common configuration for the average user).
       Each "display" is a separate instance of "X". The "display"
       includes not only the obvious video components, but also the
       keyboard, mouse and other input type components. The user can
       only access one display at a time via the same keyboard and
       monitor. "Displays" may reside locally, or on a networked host
       "somewhere", or both. It is possible that if multiple "displays"
       are available, the user can choose which one he wants when he
       logs in. Each "display" may have its own unique configuration
       (e.g. resolution). But again, the most typical configuration is
       just one "display" with one "screen", which is how most of us use
     * In reference to X servers, "screen" means the primary video
       output with which you view X. And there can be more than one
       "screen", just like you can have more than one "display".
       Additional "screens" are used in "multi-headed displays" for
       instance. In fact you can even have more than one computer
       running off a single X server. This is beyond the scope of this
       document, but you should be aware of this degree of flexibility
       as it is an important ingredient of the X protocol.
     * "Desktop" can mean different things in different contexts. Often,
       "desktop" means what is more properly called the "Desktop
       Environment". Prime examples of this are KDE, GNOME, and the not
       as well-known CDE, which are high level applications that control
       much of how the user interacts with the X session. They provide
       consistent look and feel, as well as consistent configuration and
       come bundled with their own set of utilities for common tasks.
       "Desktop" also sometimes just means the viewable screen area.
       This is more of the MS Window's meaning. X environments though
       are capable of having multiple virtual "desktops" that can be
       switched between as needed. This helps with organizing different
       tasks. Each "desktop" may its own windows and clients that are
       specific to it. Right now I have seven WindowMaker desktops
       (WindowMaker calls them "WorkSpaces"), and one of those I have
       dedicated to writing this document. This "desktop" has thirteen
       unique windows at the moment (man pages, browser windows, clock,
       gvim, xterms, etc).
     * "Clients" are any program that connect to the X server, and
       require an X server for some task (e.g. to display itself).
       Often, these are displayed in their own "window", but not always.
       For instance, if I use CTRL-N to open a new Mozilla window, this
       is one X client but with two windows. If I run a command line X
       utility like xev to view key and mouse events, this runs in the
       xterm's window, so has none of its own, but is still a "client".
       Clients can be locally running applications, or applications that
       are running on another system over the network, but are displayed
     * The "Window Manager" is a special type of client application and
       a user definable component of the GUI. It is what the user
       interacts with to a large extent. The Window Manager provides
       such functionality as window borders and decorations, menus,
       icons, virtual desktops, button bars, tool bars, and allows the
       user to customize these. It is technically possible to run X
       without a window manager (though not very functional), but not
       the other way around. Window managers should not be confused with
       "Desktop Environments" like KDE. Desktop Environments include
       their own preferred Window Manager, but this is a configurable.
       There is some overlapping of responsibilities between Window
       Managers and Desktop Environments.
     * The "root window" is the background of your screen. It is
       referred to as a window in name alone, it does not behave like
       any other window, but rather you run your applications on the
       root window, or put an image on it, or perhaps just a solid
       color. All other windows are children of this parent window. The
       root window conceivably can be larger than the viewable screen
     * The "pointer" is the arrow or indicator of any given shape which
       represents the location of your mouse, or other pointing device.
       The pointer often changes to give you contextual feedback as to
       what will happen when you use the mouse at that point on the
     * The "window" is a frame in which any given application runs and
       which is "managed" by the Window Manager. This includes pretty
       much anything except the so-called root window. Even windows
       which do not appear to have frames, titles, or normal borders of
       any kind are being managed by your window manger. The "active
       window" is the window you are currently using. This window will
       will respond to the keyboard when you type, and is traditionally
       denoted by the fact that your mouse cursor is pointing at it,
       though this is not always the case. The active window is said to
       have "focus". Most Window Managers will somehow highlight the
       "active", or focused, window to differentiate it from other
     * "Menus", "icons" and "task bars" behave in X similar to the way
       they behave in other windowing systems, and the same general
       principles apply.
     * Windows that run text only applications are called "terminal
       emulators", such as xterm and various similar applications. This
       is the well-known "command line" in an X environment. These
       basically emulate a console text-only display, and have some
       advantages due to their being used in X. These are much more
       complex and sophisticated applications than a simple DOS box on
     * "Widgets" is the term used to describe such GUI control
       components as buttons, sliders, menus, scrollbars, listboxes,
       checkboxes, etc. "Toolkits" are libraries containing a diverse
       set of widgets with the same look and feel. Some common examples
       are GTK+ (used by GNOME, Mozilla and others), Xaw (X Athena
       Widget set), Tk, Motif and QT (used by KDE). Applications are
       built with one toolkit or another. Sometimes the same application
       can be built with different toolkits, depending on compile time
     * Window "geometry" is a shorthand way of expressing a window's
       size and screen placement. This might look like "60x20+10+50",
       which is WIDTH x HEIGHT +VERT_OFFSET +HORZ_OFFSET. While both
       pairs are often specified, it is permissible to use just one or
       the other pair.
     * In X lingo, "resources" are definable application attributes.
       Commonly available "resources" are fonts, colors, size, window
       title, etc, etc.

10.2. Links and other References

     * The definitive source of information on XFree86 is, of course,
       [] Don't forget the man
       pages that you have installed already too (X, Xserver,
       XF86Config, XFree86, xdm, xinit, xmodmap, startx, xauth,
       Xsecurity, etc, etc). These are really mostly decent, though some
       are quite technical.
       Some pages at to check:

   Docs and support info: [] for various versions and topics.

   README: []

   Release Notes: []

   DRI: []

   Status: []

   Mouse: []

   Supported card list: []
     * Other related documents from LDP:
          + If you are just starting out, you may find the
            [] X
            Window System Architecture Overview HOWTO to be helpful. It
            covers all the basic concepts quite well.
          + The Remote X Apps Mini HOWTO does a nice job of discussing
            running X remotely, and related security issues of X
          + The XDMCP HOWTO covers the X Display Manager Control
            Protocol, for running X remotely. Also, The XDM and X
            Terminal mini-HOWTO .
          + The XFree86 HOWTO succinctly covers installation, and
            initial configuration.
          + The XFree86 Video Timings HOWTO gets down and dirty with the
            finer points of monitor tuning. Generally not required for
            XFree86 v4.x.
          + [] The Xinerama
            HOWTO covers multi-headed displays.
          + [] The Font HOWTO
            covers various font topics.
          + The Font De-Uglification Mini HOWTO covers a range of X font
          + The International Keyboard HOWTO
          + The Linux Infrared HOWTO
     * Looking for information on a Window Manager, or wanting to try
       something new or different: []
     * Wheel mice tips and configuration:
     * Linux and Laptops: []
     * The O'Reilly series on X Window! Visit [] for the definitive books on X.
     * The X Consortium's web site is [] ... or perhaps it's moved to
     * [] is sort of a
       clearinghouse for all things X.
     * And for everything else under the Sun: [] An incredible resource in its own



   v4.x changes:
   - artheader tag changed to articleinfo
   - graphic tag is being depricated in DocBook 5.x. To prepare for
     this, you should instead use the mediaobject tag.
   - file format for imagedata has to be in capital letters.
   - added support for PNG (notation in the DTD)
     --s+ []

    aspell -H -c ~/ldp/x-user/LDP/howto/docbook/XWindow-User-HOWTO.sgml

    cvs -d $CVSROOT login
    $cvs get LDP/howto/docbook/XWindow-User-HOWTO.sgml
    $ cvs commit XWindow-User-HOWTO.sgml      !!!!!!!!!!!!!!!!
    (from the LDP/howto/docbook/ dir)
   check here:
   Start 3.1:
   Changes: (plus freshmeat)
       VNC vs X for performance on network.
       lbxproxy, performance.
       Add fluxbox.
   Start rewrite 01/13/02 Hal Burgiss.
    Converted to DocBook
    Rewrite! Rewrite!
    A zillion changes.
    $DISPLAY (xdm) (Xclients, e
   tc) (X config, etc)
    log file
   startx &> log
   _X11TransSocketUNIXConnect: Can't connect: errno = 111 giving up.
   xinit:  Connection refused (errno 111):  unable to connect to X serve
   xinit:  No such process (errno 3):  Server error.
   ## Makefile to build this doc as HTML and TXT ####################
   # X Windows User HOWTO Makefile
   # Hal Burgiss
   TITLE = XWindow-User-HOWTO
   EXT = sgml
   SRC_DIR = LDP/howto/docbook
   SRC = $(SRC_DIR)/$(TITLE).$(EXT)
   BUILD = jade -t sgml -ihtml -d /usr/lib/sgml/stylesheets/ldp.dsl\#htm
   BUILD_TXT = jade -t sgml -i html -d /usr/lib/sgml/stylesheets/ldp.dsl
   \#html -V nochunks
   SPELL_CMD = aspell -H -c
   LINKS_CMD = /usr/bin/linkchecker *html
   EDIT_CMD = /usr/bin/vim -g
   TBROWSER = w3m
   TMP_TXT = __tmp.sgml
   SRC_URL =$(TITLE).$(EXT).gz
   all: doc txt
   doc: html
   rm -fr $(HTML_DIR)
   mkdir -p __tmp_htmls
   mv -f *.html __tmp_htmls 2>/dev/null || :
   mkdir -p $(HTML_DIR)
   $(BUILD) $(SRC) ||\
    (rm -f *.html && mv -f __tmp_htmls/* . || : && rm -rf __tmp_htmls &&
   mv -f *html $(HTML_DIR)
   mv -f __tmp_htmls/* .  2>/dev/null || :
   rm -fr __tmp_htmls
   rm -fr $(HTML_DIR) *~  __tmp_htmls
   $(EDIT_CMD) $(SRC)
   $(SPELL_CMD) $(SRC)
   spellchecker: spell
   cd $(HTML_DIR) && $(LINKS_CMD)
   linkchecker: links
   linkcheck: links
   $(BUILD_TXT) $(SRC) > $(TMP_TXT).html
   $(TBROWSER) -dump $(TMP_TXT).html > $(TITLE).txt && gzip -f $(TITLE).
   txt && rm -f $(TMP_TXT).html
   text: txt
   cp -fv $(HTML_DIR)/* $(TITLE).txt.gz $(SRC) $(WWW)
   gzip -f $(WWW)/$(TITLE).sgml
   rsync -auv $(WWW)/* feenix://$(WWW)/
   @echo "Updated and ready:  $(SRC_URL)" |\
   mail -s "$(TITLE) update" &&\
   echo " $(TITLE) Submitted!"

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