Chapter 7. The X Window System
      While the heart of Red Hat Linux is the kernel, for many users, the face of the
      operating system is the graphical environment provided by the X
      Window System, also called X.
    
      Various windowing environments have existed in the
      UNIX™ world for decades, predating many of the
      current mainstream operating systems. Through the years X has become the
      dominant graphical environment for UNIX-like operating systems.
    
      The graphical environment for Red Hat Linux is supplied by
      XFree86™, an open source implementation of
      X. XFree86 is a large scale, rapidly developing project with hundreds of
      developers around the world. It features a wide degree of support for a
      variety of hardware devices and architectures and can run on a variety of
      different operating systems and platforms.
    
      The X Window System uses a client-server architecture. The X
      server listens for connections from X
      client applications via a network or local loopback
      interface. The server communicates with the hardware, such as the video
      card, monitor, keyboard, and mouse. X client applications exist in the
      user-space, creating a graphical user interface
      (GUI) for the user and passing user requests to the
      X server.
    
7.1. XFree86
	Red Hat Linux 9 uses XFree86 version 4.x as the base X Window System, which
	includes many cutting edge XFree86 technology enhancements such as 3D
	hardware acceleration support, the XRender extension for anti-aliased
	fonts, a modular driver based design, and support for modern video
	hardware and input devices.
      
|  | Important | 
|---|
|  | 	  Red Hat Linux no longer provides XFree86 version 3 server packages. Before
	  upgrading to the latest version of Red Hat Linux, be sure the video card is
	  compatible with XFree86 version 4 by checking the Red Hat Hardware
	  Compatibility List located online at http://hardware.redhat.com.
	 | 
	The files related to XFree86 reside primarily in two locations:
      
- /usr/X11R6/
- Contains X server and some client applications as well as X header
	      files, libraries, modules, and documentation.
	     
- /etc/X11/
- Contains configuration files for X client and server
	      applications. This includes configuration files for the X server
	      itself, the older xfs font server, the X
	      display managers, and many other base components.
	     - It is important to note that the configuration file for the
	      newer Fontconfig-based font architecture is
	      /etc/fonts/fonts.conf (which obsoletes the
	      /etc/X11/XftConfig file). For more on
	      configuring and adding fonts, see Section 7.4 Fonts.
	     
	Because the XFree86 server performs advanced tasks on a wide array of
 	hardware, it requires detailed configuration. The Red Hat Linux installation
 	program installs and configures XFree86 automatically, unless the
 	XFree86 packages are not selected for installation. However, if the
 	monitor or video card changes, XFree86 will need to be reconfigured.
 	The best way to do this is to use the
 	X Configuration Tool
 	(redhat-config-xfree86).
      
	To start the X Configuration Tool while in an
	active X session, go to the  (on the
	Panel) =>  =>
	. After using the
	X Configuration Tool during an X session, changes
	will take effect after logging out and logging back in. For more about
	using the X Configuration Tool refer to the chapter
	titled Audio, Video, and General Amusement in the
	Red Hat Linux Getting Started Guide.
      
	In some situations, reconfiguring the XFree86 server may require
	manually editing its configuration file,
	/etc/X11/XF86Config. For information about the
	structure of this file, see Section 7.3 XFree86 Server Configuration Files.