Chapter 3 introduced
Linux's graphical desktops, and many subsequent chapters showed you the
spiffy and powerful tools you could run on them. Rarely do you have to
deal with the underpinnings that make all this possible, but
occasionally your screen resolution isn't as good as it could be, or you
have trouble getting graphics to start. At these times you notice that
error messages are referring to an X server or to various files and
libraries with an x in them.
Basically, the X Window System encompasses all the software that lets a CPU understand a video card and get graphics to appear on a monitor. X goes far beyond this, though: it provides an interface of almost unlimited flexibility to let programs display graphics, interact with the user, and exchange data with other graphical programs. KDE and GNOME are both sets of libraries and tools that run on X. In this chapter, we tell you how to install and configure the X Window System in case it was not done by your distribution properly.
It's difficult to describe the X Window System in a nutshell. X is a complete windowing graphics interface that runs on almost all computer systems, but was established mostly on Unix and now on Linux. X provides a huge number of options to both the programmer and the user. For instance, at least half a dozen window managers are available for X, each one offering a different interface for manipulating windows. Your distribution has chosen a window manager along with a desktop. By customizing the attributes of the window manager, you have complete control over how windows are placed on the screen, the colors and borders used to decorate them, and so forth.
X was originally developed by Project Athena at MIT, by MIT, Digital Equipment Corporation (DEC), and IBM. The version of X current as of the time of writing is Version 11 Revision 6 (X11R6 ), which was first released in April 1994 and then subsequentially updated in minor versions. Since the release of Version 11, X has virtually taken over as the de facto standard for Unix graphical environments.
Despite its commercial use, the X Window System remains distributable under a liberal license from the Open Group. As such, a complete implementation of X is freely available for Linux systems. X.org , the version most directly based on the X sources, is the version that Linux uses most often. Today, this version supports not only Intel-based systems, but also Alpha AXP, MicroSPARC, PowerPC, and other architectures. Further architectures will follow. Support for innumerable graphics boards and many other operating systems (including Linux) has been added—and X.org implements the latest version, X11R6.8.2.[*]
We should mention here that commercial X Window System servers are available for Linux that may have advantages over the stock X.org version (such as support for certain video cards). Most people use the X.org version happily, though, so this should certainly be your first stop.
As we mentioned in "Why Use a Graphical Desktop?" in Chapter 3, people who run Linux as a server often don't install X at all. They control the server through remote access only, or using just the text interface.
[*] X.org is a relatively new version. There have been infights in the X Window System community that have led to a split; people have moved from the previously prevailing XFree86 version to the newer X.org version. We will not comment any further on these infights, as they are more a question of personal animosities than of technical benefits.