Chapter 6. The X Window System

103

to work in that environment to commonly integrate and be used in new ways, such as permitting

drag and drop behavior with text.

GNOME is the default desktop environment for Red Hat Linux, using the GTK2 base widget toolkit

and miscellaneous other widgets that extend the base functionality. KDE, another desktop environ 

ment, uses a different toolkit called Qt. GNOME and KDE both contain advanced productivity ap 

plications, such as word processors, spreadsheets, and control panel devices that allow you to have

complete control of the look and feel of your user experience. Both environments can run standard X

client applications, and most KDE applications can run in GNOME, if the Qt libraries are installed.

When you start X using the

startx

command, a pre specified desktop environment is utilized. To

change the default desktop environment used when X starts, open a terminal and type the

switchdesk

command. This brings up a graphical utility that allows you to select the desktop environment or

window manager to use the next time X starts.

Desktop environments utilize window managers to provide the consistency in appearance between

different applications. KDE contains its own window manager, called

kwm

, specifically for this func 

tionality.

For information on the customization of the GNOME and KDE desktop environments, see the Official

Red Hat Linux Getting Started Guide.

6.4. Runlevels

Most users run X from runlevels 3 or 5. Runlevel 3 places your system in multi user mode with

full networking capabilities. The machine will boot to a text based login prompt with all necessary

preconfigured services started. Most servers are run in runlevel 3, as X is not necessary to provide any

services utilized by most users. Runlevel 5 is similar to 3, except that it automatically starts X and

provides a graphical login screen. Many workstation users prefer this method, because it never forces

them to see a command prompt.

The default runlevel used when your system boots can be found in the

/etc/inittab

file. If you

have a line in that file that looks like

id:3:initdefault:

, then your system will boot to runlevel

3. If you have a line that looks like

id:5:initdefault:

, your system is set to boot into runlevel 5.

As root, change the runlevel number in this file to set a different default. Save the file and restart your

system to verify that it boots to the correct runlevel. More information on runlevels can be found in

Section 3.6.

6.4.1. Runlevel 3:

startx

When in runlevel 3, the preferred way to start an X session is to type the

startx

command.

startx

, a

front end to the

xinit

program, launches the XFree86 server and connects the X clients to it. Because

you must already be logged into the system at runlevel 3 to be able to type commands,

startx

is only

designed to bring up certain X clients, such as a desktop environment, in a particular manner. It does

not provide any user authentication.

When

startx

begins, it looks for a

.xinitrc

file in the user's home directory to define the X clients

to run. If it does not find that file present, it will run the system default

/etc/X11/xinit/xinitrc

script instead. The

startx

script then does the same thing with the

.xserverrc

file, looking for

it in the user's home directory and then running the default

/etc/X11/xinit/xserverrc

script if

it cannot be found. Since many different X clients exist, the

xinitrc

files are very important. The

xserverrc

script is less important. It only sets the X server to connect to the X clients. Since the

default X server is already configured with the

/etc/X11/X

link, Red Hat Linux does not install a

default

xserverrc

.

The default

xinitrc

script then looks for user defined files and default system files, including

.Xre 

sources

,

.Xmodmap

, and

.Xkbmap

in the user's home directory and

Xresources

,

Xmodmap

, and

Xkbmap

in the

/etc/X11/

directory. The

Xmodmap

and

Xkbmap

files, if they exist, are used by the