GNOME core components include:

• Control Center: This collection of applications customizes
  the GNOME environment.
  
• gnome-panel
  : This application provides the tool bar and menu
  system to launch applications and host panel applets.
  Panel also interfaces with session manager (gnome-session)
  
  when exiting the desktop.
  Panel also interfaces with session-manager when exiting the desktop
  and managing "saved" sessions when launching the desktop.
  
• nautilus
  : Manages desktop icons and provides a file manager.
  
• gdm
  : GNOME Display Manager (login screen) This handles X-Authentication,
  netwrk desktop access (XDMCP), graphical login prompt, logos, ...
  
• GNOME
  VFS: Uses mime types for transparent file access.
  
• Window manager. None specified. Can use Metacity, Sawfish,
  ...
  
• Component management:
  
  
  • Bonobo:
    Components defined by gnome-dom Document Object Model (DOM) XML model.
    
  • ORBit:
    CORBA Object Request Broker (ORB). Makes onjects accessible.
    
    
    (Uses: /usr/bin/gnome-name-service)
    

All GNOME configuration files use XML representation.

If the system is configured to boot to run level 3 (console mode) the
X-Windows is started by the command xinit. If configured to
boot to
run level 5 then the gdm will be executed at system start-up.
The choice of using the KDE (kdm) or GNOME (gdm) login manager is set in
the
config file /etc/sysconfig/desktop. There are two options:

• DESKTOP="GNOME"
  
  
  (Configure with: /usr/sbin/gdmsetup)
  
  
  or
  
• DISPLAYMANAGER="KDE"
  

GDM Startup:

1. X-Windows command xinit:
   
   
   • /etc/X11/xinit/xinitrc
     
     
     which sets the environment and calls:
     
   • /etc/X11/xinit/xinitrc-common
     
     
     which set the root window, sets resource files for the:
     
     
     • keyboard (/etc/X11/Xmodmap)
       
     • fonts (/etc/X11/Xresources)
       
     • ...
       

     and executes X-Windows start-up scripts
     in /etc/X11/xinit/xinitrc.d/...
     

   • /etc/X11/xinit/xinput.d/...
     
     
     language configurations ...
     
   • 
     
     

2. The login screen: /usr/bin/gdm
   
3. X-windows script /etc/X11/xdm/Xsession starts
   X-windows session
   and then calls /usr/bin/gnome-session
   
4. gnome-session
   :
   This sets up GNOME desktop environment.
   
   

   Config file: /usr/share/gnome/default.session
   
   

   
   

   
   

   
   
   

   
   

   view source print? 01 # This is the default session that is launched if the user doesn't 02 # already have a session. 03 # The RestartCommand specifies the command to run from the $PATH. 04 # The Priority determines the order in which the commands are started 05 # (with Priority = 0 first) and defaults to 50. 06 # The id provides a name that is unique within this file and passed to the 07 # app as the client id which it must use to register with gnome-session. 08 # The clients must be numbered from 0 to the value of num_clients - 1. 09   10 [Default] 11 num_clients=7 12 0,id=default0 13 0,Priority=60 14 0,RestartCommand=<b>pam-panel-icon</b> --sm-client-id default0 15 1,id=default1 16 1,Priority=10 17 1,RestartCommand=<b>gnome-wm</b> --default-wm gnome-wm --sm-client-id default1 18 2,id=default2 19 2,Priority=40 20 2,RestartCommand=<b>gnome-panel</b> --sm-client-id default2 21 3,id=default3 22 3,Priority=40 23 3,RestartCommand=<b>nautilus</b> --no-default-window --sm-client-id default3 24 4,id=default4 25 4,Priority=60 26 4,RestartCommand=<b>rhn-applet-gui</b> --sm-client-id default4 27 5,id=default5 28 5,Priority=50 29 5,RestartCommand=<b>eggcups</b> --sm-client-id default5 30 6,id=default6 31 6,Priority=40 32 6,RestartCommand=<b>magicdev</b> --sm-client-id default6

   This config file lists the GNOME processes to start.
   
   

   
   GUI configuration tools:
   

   
   

   • /usr/bin/gnome-session-properties
     
     

     
     
     

   • /usr/bin/gnome-session-remove
     
   • /usr/bin/gnome-session-save
     

   
   

   
   gnome-session executable and config file starts:
   

   
   
   • pam-panel-icon
     
   • gnome-wm
     (Script /usr/bin/gnome-wm to start window manager)
     
     
     Script also identified in config file: /usr/share/gnome/default.wm
     
     

     
     
     
     
     
     
     
     

     view source print? 1 [Default] 2 WM=gnome-wm

     
     

     Uses first window manager found in list in script: i.e. metacity sawfish sawmill
     enlightenment icewm wmaker fvwm2 qvwm fvwm twm kwm
     
     

     Gnome-wm also uses environment variable: WINDOW_MANAGER
     
     

     Script then uses gconftool to set gconf key.
     (gconf key: /desktop/gnome/applications/window_manager/default)
     Also starts omf
     
     

     Configure with /usr/bin/gnome-session-properties
     

   • gnome-panel
     (toolbar)
     
     
     Configure with gnome-panel-properties-capplet
     
     
     Add launcher with gnome-panel-add-launcher
     
   • nautilus
     : Manages desktop icons and provides a file manager.
     
   • rhn-applet-gui : up2date and network alert
     notification tool.
     
   • eggcups : printer support
     
   • magicdev
     
     
     CD and DVD mounter. Config tool: gnome-cd-properties
     
     
     Config files:
     
     
     • /etc/gconf/schemas/magicdev.schemas
       
     • /usr/share/applications/gnome-cd-properties.desktop
       

   Also uses ~/.gnome/session (Mine is empty)
   
   

   Can save with save-session for later start-up.
   

GDM commands:

• GDM Configuration GUI: /usr/sbin/gdmconfig (same as
  gdmsetup)
  
  

  
  
  

• Re-Start:
  
  
  • Red Hat/Fedora Core: /usr/sbin/gdm-restart
    
    
    /usr/sbin/gdm-safe-restart
    
  • S.u.S.e.: /opt/gnome/sbin/gdm-restart
    
    
    /opt/gnome/sbin/gdm-safe-restart
    

• Stop:
  
  
  • Red Hat/Fedora Core: /usr/sbin/gdm-stop
    
  • S.u.S.e.: /opt/gnome/sbin/gdm-stop
    

Components: ORBit: CORBA drag-drop Uses libgnorba for CORBA registry
which calls gnome-name-service.
gnome-name-service - Orbit name service GOAD is the GNOME Object
Activation
Directory.
It keeps track of the CORBA object implementations on system.

Red Hat / Fedora Packages: usermode-gtk gnome-session magicdev
gnome-panel

Also see the YoLinux
init process tutorial

The GNOME desktop will generate the following configuration files and
directories in the users home directory:

File/Directory	Description
.esd_auth	[File] Enlightened Sound Daemon (ESD) authentication cookie.
.gconf	[Directory] User preferences stored here.
.gconfd	[Directory] gconfd daemon information stored here. CORBA IOR and object info.
.gnome	[Directory] User info not held in .gconf. i.e. mime type info.
.gnome2	[Directory] User info not held in .gconf. i.e. Window location, keyboard shortcut info, ...
.gnome-private	[Directory] Empty. Not used??
.gnome2-private	[Directory] Empty. Not used??
Desktop .gnome-desktop (older RH 8/9)	[Directory] Desktop icons and application launchers.
.nautilus	[Directory] Nautilus file manager data.
.thumbnails	[Directory] Thumbnail images generated and used by Nautilus.
.metacity	[Directory] Metacity window manager data.
.themes	[Directory] Theme options, window frame options, ...
.screensaver	[Directory] Screensaver configuration data. Command to set defaults: xscreensaver-demo Command to control xscreensaver process: xscreensaver-command System configuration data stored in: /usr/X11R6/lib/X11/app-defaults/XScreenSaver

GConf is used by GNOME to expose settings to multiple applications.
GConf is the GNOME way of persisting application settings and should be
used by
GNOME application programmers. GConf includes notification service
alerts to
applications to changes in configuration data, and is used by GNOME
itself.
A command line tool (gconftool, FC3 /usr/bin/gconftool-2)
and a simple GUI application (gconf-editor) are supplied to
facilitate administration.

gconf-editor

GNOME primary configuration GUI tool: gnome-control-center

Command	Description
GNOME Configuration and Properties (This single command ties in most of the commands below into a single GUI.)	/usr/bin/gnome-control-center
GNOME Display Properties (X-Windows resolution)	/usr/bin/gnome-display-properties
GNOME Window Properties (X-Windows Properties)	/usr/bin/gnome-window-properties
GNOME Desktop Keyboard Properties	/usr/bin/gnome-accessibility-keyboard-properties (RH 9.0, FC 1/2/3)
GNOME Desktop Keybinding Properties	/usr/bin/gnome-keybinding-properties (RH 9.0, FC 1/2/3)
GNOME Desktop Keyboard Layout	/usr/bin/gnome-keyboard-layout (FC 3)
GNOME Desktop Keyboard Properties	/usr/bin/gnome-keyboard-properties (FC 3)
GNOME Mouse Properties	/usr/bin/gnome-mouse-properties (FC 3)
GNOME Desktop Network Configuration	/usr/bin/gnome-network-preferences (RH 9.0, FC 1/2/3))
GNOME Sound Properties	/usr/bin/gnome-sound-properties (RH 9.0, FC 1/2/3)
GNOME Volume Control	/usr/bin/gnome-volume-control (FC 3)
GNOME Volume Properties Device specific)	/usr/bin/gnome-volume-properties (FC 3)
GNOME Audio Profiles (CD quality, ...)	/usr/bin/gnome-audio-profiles-properties (FC 3)
GNOME Theme Manager (Desktop look)	/usr/bin/gnome-theme-manager (FC 3)
GNOME Background Properties (Wallpaper)	/usr/bin/gnome-background-properties (FC 3)
GNOME Bluetooth Manager	/usr/bin/gnome-bluetooth-manager (FC 3)
GNOME desktop options and GNOME applications configuration	/usr/bin/gconf-editor (RH 8.0+ ... FC 3)
GNOME desktop properties configuration	/usr/bin/gnome-session-properties (RH 8.0+) (Use gnome-session-save or select save on exit to store settings. If you mess up, delete $HOME/.gnome2/session*.)
GNOME desktop Character Map configuration	/usr/bin/gnome-character-map (FC 3)
GNOME desktop font configuration (run as root)	/usr/bin/redhat-update-gnome-font-install (RH 9.0 - FC 3) /usr/bin/redhat-update-gnome-font-install2
GNOME Font properties	/usr/bin/gnome-font-properties
GNOME Font Viewer	/usr/bin/gnome-font-viewer
GNOME desktop properties save	/usr/bin/gnome-session-save (RH 8.0+)
GNOME session properties	/usr/bin/gnome-session-properties
GNOME Panel Preferences	/usr/bin/gnome-panel-preferences (RH 8.0,9.0) (Also see gnome-panel-screenshot)
GNOME Desktop User Interface Properties	/usr/bin/gnome-ui-properties
GNOME Desktop File Types and Properties	/usr/bin/gnome-file-types-properties (RH 9.0)
GNOME Desktop Item Edit	/usr/bin/gnome-desktop-item-edit
GNOME Default Application Configuration (Default web browser, Mail reader, ...)	/usr/bin/gnome-default-applications-properties
GNOME Default Printer	/usr/bin/gnome-default-printer
GNOME Database Properties	/usr/bin/gnome-database-properties
GNOME Help	/usr/bin/gnome-help
GNOME About	/usr/bin/gnome-about

Note: The S.u.s.e. distribution locates Gnome commands in /opt/gnome/bin/...
The Red Hat/Fedora distribution locates commands in /usr/bin/...
as described in the table above.

For a list of all Red Hat configuration commands (keyboard, sound, ...)
see the
YoLinux
Tutorial on Red Hat installation and system Re-Configuration

GNOME has also been stepping outside it's desktop world to include some
computer systems configuration. See: gnome-nettool

Commands for developers: /usr/bin/gnome-config (script), gnome-doc,
gnome-dump-metadata,
gnome-gen-mimedb, gnome-obex-send,
gnome-obex-server, gnome-theme-thumbnailer, gnome-thumbnail-font,
gnome-typing-monitor, gnome-vfs-config

If your corporate environment uses a proxy (which so many do) then
configure the GNOME desktop to utilize this proxy.

• Select "Start Here" Desktop icon. This will start the
  Nautilus configuration tool.
  
• Select the "Preferences" icon.
  
• Then select the "Network Proxy" icon.
  
• HTTP Proxy: proxy.mega-corp.com Port: 80
  
  
  Also enter your proxy login and password.
  

One can also enter the command: /usr/bin/gnome-network-preferences

This enters the configuration in the file: /home/user1/.gconf/system/http_proxy/%gconf.xml

Shortcut	Description
F1	Launch Gnome help system. If pressed in a Gnome aware application, the help document for the given application is opened. Otherwise, the GNOME main help page is opened.
F2	Raise the current window to the top of the desktop or to the foreground. This is the same affect achieved by mouse clicking on a window.
Menu	Opens the main desktop menu. This key can be used from within any GUI application. This key is located next to the Ctrl key in the lower-right part of the keyboard.

Location of ".desktop" Definition File:

Menus are specified by ".desktop" files located in one of the following
directories:

• /usr/share/gnome/apps/
  
• /etc/X11/applnk/
  
• /usr/share/applnk/
  
• $HOME/.gnome/apps/
  
  
  (Private menues)
  

Definition File: (".desktop")

Example desktop menu file for a single application: /usr/share/applications/gnome-gcalctool.desktop

view source print? 01 [Desktop Entry] 02 Encoding=UTF-8 03 Name=Calculator 04 Name[ca]=Calculadora 05 Name[it]=Calcolatrice 06 ... 07 Comment=Perform calculations 08 Comment[ca]=Calcula 09 Comment[it]=Esegue vari calcoli 10 ... 11 Exec=gcalctool 12 Icon=gnome-calculator 13 Terminal=false 14 Type=Application 15 Categories=GNOME;Application;Utility; 16 X-GNOME-DocPath=gcalctool/gcalctool.xml 17 X-GNOME-Bugzilla-Bugzilla=GNOME 18 X-GNOME-Bugzilla-Product=gcalctool 19 X-GNOME-Bugzilla-Component=general 20 X-GNOME-Bugzilla-OtherBinaries=gnome-calculator 21 X-Desktop-File-Install-Version=0.9 22 OnlyShowIn=GNOME;

Note:

• Icon file reference or explicit icon file name can be
  used:
  
  Icon=gnome-calculator
  
  or
  
  Icon=/usr/share/pixmaps/gnome-calculator.xpm
  
• One can use the words true/false or numerical
  representation 1/0:
  
  Terminal=0
  

Notes:

• Icon: Icons of various sizes but of the same name are
  all located in:
  
  
  • /usr/share/icons/Bluecurve/32x32/apps/gnome-calculator.png
    
  • /usr/share/icons/Bluecurve/16x16/apps/gnome-calculator.png
    
  • /usr/share/icons/Bluecurve/24x24/apps/gnome-calculator.png
    
  • /usr/share/icons/Bluecurve/36x36/apps/gnome-calculator.png
    
  • /usr/share/icons/Bluecurve/48x48/apps/gnome-calculator.png
    
  • /usr/share/icons/hicolor/32x32/apps/gnome-calculator.png
    
  • /usr/share/icons/hicolor/48x48/apps/gnome-calculator.png
    

• Terminal: Two options
  
  
  1. true: Launch an ASCII text terminal in which to run application.
     
  2. false: Does not require a text terminal.
     

• Type: Two options
  
  
  1. Application: This option starts an application
     
  2. Link: Link to file, folder (directory) or URL.
     

• Categories: Item descriptions as specified by a standard
  category keyword in the desktop menu specification at FreeDesktop.org
  
• X-GNOME-DocPath: File to display when user selects
  "Help" on application name.
  

KDE: /usr/share/applnk/Multimedia/RealPlayer.kdelnk

view source print? 01 [KDE Desktop Entry] 02 Comment=RealPlayer 03 SwallowTitle= 04 SwallowExec= 05 BinaryPattern=realplayer;RealPlayer; 06 Name=RealPlayer8 07 Exec=/usr/lib/RealPlayer8/realplay 08 Icon=/usr/lib/RealPlayer8/rp7.xpm 09 MiniIcon=/usr/lib/RealPlayer8/rp7mini.xpm 10 TerminalOptions= 11 Path= 12 Type=Application 13 Terminal=0 14 MimeType=audio/x-pn-realaudio;audio/vnd.rn-realaudio;

Sub-Menus:

Definition file:

• /usr/share/desktop-directories/Accessories.directory
  
• /usr/share/gnome/vfolders/Accessories.directory
  

view source print? 01 [Desktop Entry] 02 Name=Accessories 03 Name[ca]=Accessoris 04 Name[it]=Accessori 05 ... 06 Comment=Desktop accessories 07 Comment[ca]=Accessoris d'escriptori 08 Comment[it]=Accessori desktop 09 ... 10 Icon=redhat-accessories.png 11 Type=Directory 12 Encoding=UTF-8

Notes:

• List order of menu items:
  
  
  • GNOME specifies with the ".order" file.
    
  • KDE is alphabetical
    

• GNOME refreshes every read. KDE caches. Restart KDE to pick
  up changes.
  

Launch applications from a double click of a desktop icon by creating a
desktop launcher.

Right mouse click on the GNOME desktop and select "Create Launcher".

view source print? 01 [Desktop Entry] 02 Encoding=UTF-8 03 Version=1.0 04 Type=Application 05 Exec=/path/to/command command arguments 06 TryExec=/path/to/command-to-execute-first command arguments 07 X-GNOME-DocPath= 08 Terminal=true 09 Name[en_US]=name-of-launcher 10 Comment[en_US]=This is a comment

• Execute string of commands as one bash command:
  
  
  
  
  
  
  

  Type=Application Terminal=true Exec=bash -c "cd /dir/path;/command/path/exe" ...

  
  
• Specify path:
  
  
  
  
  
  
  

  Type=Application Terminal=true Path=/dir/path Exec=/path/to/command command arguments ...

  
  

• http://g-scripts.sourceforge.net/
  - Script functionality within Nautilus.
  

• Check for errors in the file $HOME/.xsession-errors
  
• Fix the error: "Failed to activate
  'OAFID:GNOME_SettingsDaemon"
  This annoying dialog box may appear after one logs in. Themes, sounds
  or background may cease to operate properly. You may also get the error
  message "The Settings Daemon restarted too many times."
  
  

  To fix this condition run the script: /usr/bin/oaf-slay
  
  
  This script will kill OAF processes on systems using OAF and bonobo.
  

  
  
• Everything messed up for user1! As root in console
  mode (ctrl-alt-F1)
  
  
  • init 3
    
  • cd /home/user1
    
  • rm -Rf .gtkrc .esd_auth .gconf .gconfd .gnome
    .gnome2 .gnome-private .gnome2-private .nautilus .thumbnails .metacity
    .themes .screensaver
    
  • cp -R /etc/skel/.gtkrc .
    
  • chown user1.user1 .gtkrc
    
  • rm -Rf /tmp/gconfd-user1 /tmp/orbit-user1
    
  • init 5
    

• I was getting an error dialog box each time I attempted to
  launch gnome-terminal. I had the environment variable
  LD_LIBRARY_PATH pointing to a conflicting set of libraries
  and
  exported GNOME applications registering to my desktop.
  It was fixed using the above technique (file and directory cleanup),
  unsetting the environment variable LD_LIBRARY_PATH and
  restarting
  X-Windows. (init 3 then init 5).
  
  

  The error if I start from an "xterm" was:
  
  

  
  
  

  
  

  
  
  
  
  

  (gnome-terminal:1354): GLib-GObject-WARNING **: cannot create instance of abstract (non-instantiable) type `GtkWidget'

  
  

• Fixing just the GNOME panel:
  
  
  • killall gnome-panel
    
  • rm $HOME/.gnome/panel
    
  • gnome-panel &
    

• Using the window manager on a second and separate monitor.
  I personally recommend using a single desktop for two monitors but if
  separate:
  
  • DISPLAY=:0.1 sh -c 'sawfish& gnome-panel&'
    

• Desktop launcher icons: (located in ~/Desktop/application-name.desktop)
  
  
  Problem: When you use a file server to provide a single home directory
  for multiple distros and versions of Linux, one quickly finds that the
  icons from system to system are NOT located in the same directory path,
  nor are the icons all available on all systems.
  
  Solution: Create a local icons directory (~/DesktopIcons).
  Copy icons to this directory and reference them in your launcher.
  

• GNOME.org
  
• Novell
  Linux Desktop GNOME User Guide
  
• Novell
  GNOME Configuration for Administrators
  
• Sawfish window
  manager
  
• http://www.freedesktop.org/
  - Desktop standards
  
• Gnome
  2.4 overview
  
• DocBook
  Standard
  - Help menus in /usr/share/gnome/help/... Use html files or
  XML
  
  
  • GNOME
    Help Menu DTD
    

• IRC Help: irc.gnome.org
  
  
  #fedora-desktop
  

Related YoLinux Tutorials:

• GTK+
  Programming Tips
  
• XML
  and GNOME libXML2
  
• GDK
  threads programming