Basis X Applications

The X Windows System, or simply X, is the standard graphical user interface (GUI) for Linux machines. X is a powerful environment which supports many applications and allows the user to open new windows and applications. Each new open window corresponds to a new shell. The mouse is usually used in X-Windows although it is not required.

X-specific applications include games, graphics, programming utilities, and documentation tools. Linux and X together transform the computer into a workstation. Networked computers running on both Linux and X can even display X applications running on remote servers elsewhere.

The X Windows System was originally developed at the Massachusetts Institute of Technology and is available for free. Many commercial vendors offer their own proprietary variants with enhanced features. Linux supports XFree86, a port of X11R6 that supports a variety of hardware such as VGA, Super VGA, and accelerated video adaptors. XFree86 is a complete distribution of the X Windows and contains the X server, a variety of applications, utilities, libraries, and documentation.

Basic X applications

A window manager controls the interface of the X Window System. Window positioning, resizing, minimizing and maximizing, frame format, and so on are handled by the window manager. The Tab Window Manager or twm, the classic window manager, comes with XFree86. Some advanced managers like the Open Look Virtual Window Manager (olvwm) and fvwm (this uses very little memory) are also available.

The XFree86 distribution includes programming libraries for X applications. Athena and Open Look are some of these applications; a 3-D graphics programming interface called PEX is also available.

The Linux binary distribution of XFree86 is always part of all Linux distributions and can also be found at a number of FTP sites. Typically, the distribution you downloaded automatically installed X for you and you only have to type 'xinit' at the main console to start up X Windows.

If X is installed, starting up the GUI involves logging into Linux at the main console (only a CLI) after booting the system and entering the command 'startx'. The startx command is actually a front-end command to the 'xinit' command, which starts the X server process and configured client applications. X applications can take settings from an X resources database, configuration files, or the command line. However, using xstart after booting and logging into the CLI is not the best way to start X and has limitations.

X windows comes with the XDM display manager. Other popular managers include KDE and GNOME. The X startup process should be automated by configuring a display manager to present an automatic GUI based login screen and authenticate users. If authentication is successful, the display manager starts an X windows session for the user on the system and loads up the X GUI. The GUI is displayed on the screen where the user signed in; this may be a local display or a display connected to a remote Linux server. This setup is preformed automatically during installation for most Linux Distributions. Searching for files with 'dm' in their names in the /etc/init.d directory will give you an idea about where and how your X display manager is configured.

Individual user interfaces may be configured through window managers like twm, fvwm, and fvwm2 or desktops such as KDE and GNOME. A window manager may be started up after loading X via 'xinit' by typing 'twm &' at the command prompt. Desktops provide a consistent user experience but are resource hungry. Window managers are therefore still quite popular.