The GNOME and KDE Desktops
Two alternative desktop GUIs can be installed on most Linux systems: GNOME and KDE. Each has its own style and appearance. GNOME uses the Clearlooks theme for its interface with the distribution screen background and menu icon as its default.
It is important to keep in mind that though the GNOME and KDE interfaces appear similar, they are really two very different desktop interfaces with separate tools for selecting preferences. The Preferences menus on GNOME and KDE display very different selections of desktop configuration tools.
Though GNOME and KDE are wholly integrated desktops, they in fact interact with the operating system through a window manager—Metacity in the case of GNOME and the KDE window manager for KDE. You can use a different GNOME- or KDE-compliant window manager if you wish, or simply use a window manager in place of either KDE or GNOME. You can find detailed information about different window managers available for Linux from the X11 website at xwinman.org.
KDE
The K Desktop Environment (KDE) displays a panel at the bottom of the screen that looks very similar to one displayed on the top of the GNOME desktop. The file manager appears slightly different but operates much the same way as the GNOME file manager. There is a Control Center entry in the Main menu that opens the KDE control center, from which you can configure every aspect of KDE, such as themes, panels, peripherals like printers and keyboards, even the KDE file manager’s web browsing capabilities.
XFce4
The XFce4 desktop is a new lightweight desktop designed to run fast without the kind of overhead seen in full-featured desktops like KDE and GNOME. It includes its own file manager and panel, but the emphasis is on modularity and simplicity. The desktop consists of a collection of modules, including the xffm file manager, the xfce4-panel panel, and the xfwm4 window manager. In keeping with its focus on simplicity, its small scale makes it appropriate for laptops or dedicated systems that have no need for the complex overhead found in other desktops.
GNOME
The GNOME desktop display shows three menus: Applications, Places, and System. The Places menu lets you easily access commonly used locations like your home directory, the desktop folder for any files on your desktop, and the Computer window, through which you can access devices, shared file systems, and all the directories on your local system. The System menu includes Preferences and Administration menus. The Preferences menu is used for configuring your GNOME settings, such as the theme you want to use and the behavior of your mouse.
To move a window, left-click and drag its title bar. Each window supports Maximize, Minimize, and Close buttons. Double-clicking the title bar will maximize the window. Each window will have a corresponding button on the bottom panel. You can use this button to minimize and restore the window. The desktop supports full drag-and-drop capabilities. You can drag folders, icons, and applications to the desktop or other file manager windows open to other folders. The move operation is the default drag operation (you can also press the SHIFT key while dragging). To copy files, press the CTRL key and then click and drag before releasing the mouse button. To create a link, hold both the CTRL and SHIFT keys while dragging the icon to the location where you want the link, such as the desktop.
GNOME provides several tools for configuring your desktop. These are listed in the System | Preferences menu. Configuration preference tools are organized into several submenus: Personal, Look and Feel, Internet and Network, Hardware, and System. Those that do not fall into any category are listed directly. Several are discussed in different sections in this and other chapters. The Help button on each preference window will display detailed descriptions and examples. Some of the more important tools are discussed here.
The Keyboard Shortcuts configuration (Personal | Keyboard Shortcuts) lets you map keys to certain tasks, for example, mapping multimedia keys on a keyboard to media tasks such as play and pause. The File Management configuration (Personal | File Management) lets you determine the way files and directories are displayed, along with added information to show in icon captions or list views. The Windows configuration (Look and Feel | Windows) is where you can enable features like window roll-up, window movement key, and mouse window selection.
The Mouse and Keyboard preferences are the primary tools for configuring your mouse and keyboard (Hardware | Keyboard and Hardware | Mouse). The Mouse preferences let you choose a mouse image and configure its motion and hand orientation. The Keyboard preferences window shows several panels for selecting your keyboard model (Layout), configuring keys ( Layout Options) and repeat delay (Keyboard), and even enforcing breaks from power typing as a health precaution.
GNOME and KDE Applets
GNOME applets are small programs that operate off your panel. It is very easy to add applets. Right-click the panel and select the Add entry. This lists all available applets. Some helpful applets are dictionary lookup; the current weather; the system monitor, which shows your CPU usage; the CPU Frequency Scaling Monitor for Cool and Quiet processors; and Search, which searches your system for files, as well as Lock, Shutdown, and Logout buttons. Some of these, including Find, Lock, and Logout, are already on the Places menu. You can drag these directly from the menu to the panel to add the applet. Following the web browser and email icons, you have, from left to right: Search for files, dictionary lookup, Tomboy note taker, Network connection monitor, CPU scaling monitor, System Monitor, Weather report, Eyes that follow your mouse around, User Switcher, and the Logout, Shutdown, and Lock Screen buttons.
On KDE, right-click the panel and select Add Applet to Panel. From the KDE applets window, you can select similar applets such as System Monitor and Sound Mixer.
Starting a GUI from the Command Line
Once logged in to the system from the command line, you still have the option of starting an X Window System GUI, such as GNOME or KDE. In Linux, the command startx starts a desktop. The startx command starts the GNOME desktop by default. Once you shut down the desktop, you will return to your command line interface, still logged in.