Once an X server is running, X client applications can connect to it and create a GUI for the user. A range of GUIs are possible with Red Hat Enterprise Linux, from the rudimentary Tab Window Manager to the highly developed and interactive GNOME desktop environment that most Red Hat Enterprise Linux users are familiar with.
To create the latter, more comprehensive GUI, two main classes of X client application must connect to the X server: a desktop environment and a window manager.
35.2.1. Desktop Environments
A desktop environment integrates various X clients to create a common graphical user environment and development platform.
Desktop environments have advanced features allowing X clients and other running processes to communicate with one another, while also allowing all applications written to work in that environment to perform advanced tasks, such as drag and drop operations.
Red Hat Enterprise Linux provides two desktop environments:
Both GNOME and KDE have advanced productivity applications, such as word processors, spreadsheets, and Web browsers; both also provide tools to customize the look and feel of the GUI. Additionally, if both the GTK+ 2 and the Qt libraries are present, KDE applications can run in GNOME and vice-versa.
Window managers are X client programs which are either part of a desktop environment or, in some cases, stand-alone. Their primary purpose is to control the way graphical windows are positioned, resized, or moved. Window managers also control title bars, window focus behavior, and user-specified key and mouse button bindings.
Four window managers are included with Red Hat Enterprise Linux:
The KWin window manager is the default window manager for KDE. It is an efficient window manager which supports custom themes.
The Metacity window manager is the default window manager for GNOME. It is a simple and efficient window manager which also supports custom themes. To run this window manager, you need to install the
The Motif Window Manager (
mwm) is a basic, stand-alone window manager. Since it is designed to be a stand-alone window manager, it should not be used in conjunction with GNOME or KDE. To run this window manager, you need to install the
The minimalist Tab Window Manager (
twm, which provides the most basic tool set of any of the window managers, can be used either as a stand-alone or with a desktop environment. It is installed as part of the X11R7.1 release.
To run any of the aforementioned window managers, you will first need to boot into Runlevel 3. For instructions on how to do this, refer to Section 18.1, “Runlevels”
Once you are logged in to Runlevel 3, you will be presented with a terminal prompt, not a graphical environment. To start a window manager, type
xinit -e <path-to-window-manager> at the prompt.
<path-to-window-manager> is the location of the window manager binary file. The binary file can be located by typing
which window-manager-name, where
window-manager-name is the name of the window manager you want to run.
xinit -e /usr/bin/twm
The first command above returns the absolute path to the
twm window manager, the second command starts
To exit a window manager, close the last window or press Ctrl+Alt+Backspace. Once you have exited the window manager, you can log back into Runlevel 5 by typing
startx at the prompt.