System originally from the X.Org Foundation (http://www.x.org). The X Window System provides a framework on which different types of desktop environments or simple window managers can be built. A replacement for X.Org called Wayland (http://wayland.freedesktop.org) is being developed. Although Wayland is the default X server for Fedora now, you can still choose X.Org instead.
The X Window System (sometimes simply called X) was created before Linux existed, and it even predates Microsoft Windows. It was built to be a lightweight, networked desktop framework.
X works in sort of a backward client/server model. The X server runs on the local system, providing an interface to your screen, mouse, and keyboard. X clients (such as word processors, music players, and image viewers) can be launched from the local system or from any system on your network to which the X server gives permission to do so.
X was created in a time when graphical terminals (thin clients) simply managed the keyboard, mouse, and display. Applications, disk storage, and processing power were all on larger centralized computers. So, applications ran on larger machines but were displayed and managed over the network on the thin client. Later, thin clients were replaced by desktop personal computers. Most client applications on PCs ran locally using local processing power, disk space, memory, and other hardware features, while applications that did not start from the local system were not allowed.
X itself provides a plain gray background and a simple “X” mouse cursor. There are no menus, panels, or icons on a plain X screen. If you were to launch an X client (such as a terminal window or word processor), it would appear on the X display with no border around it to move, minimize, or close the window. Those features are added by a window manager.
A window manager adds the capability to manage the windows on your desktop and often provides menus for launching applications and otherwise working with the desktop. A full-blown desktop environment includes a window manager, but it also adds menus, panels, and usually an application programming interface that is used to create applications that play well together.
So how does an understanding of how desktop interfaces work in Linux help you when it comes to using Linux? Here are some of the ways:
Because Linux desktop environments are not required to run a Linux system, a Linux system may have been installed without a desktop. It might offer only a plain-text, command-line interface. You can choose to add a desktop later. After it is installed, you can choose whether to start up the desktop when your computer boots or start it as needed.
For a very lightweight Linux system, such as one meant to run on less powerful computers, you can choose an efficient, though less feature-rich, window manager (such as twm or fluxbox) or a lightweight desktop environment (such as LXDE or Xfce).
For more robust computers, you can choose more powerful desktop environments (such as GNOME and KDE) that can do things such as watch for events to happen (such as inserting a USB flash drive) and respond to those events (such as opening a window to view the contents of the drive).
You can have multiple desktop environments installed and you can choose which one to launch when you log in. In this way, different users on the same computer can use different desktop environments.
Many different desktop environments are available to choose from in Linux. Here are some examples:
GNOME GNOME is the default desktop environment for Fedora, Red Hat Enterprise Linux, and many others. Think of it as a professional desktop environment focusing on stability more than fancy effects.
K Desktop Environment KDE is probably the second most popular desktop environment for Linux. It has more bells and whistles than GNOME and offers more integrated applications. KDE is also available with Fedora, Ubuntu, and many other Linux systems. For RHEL 8, KDE was dropped from the distribution.
Xfce The Xfce desktop was one of the first lightweight desktop environments. It is good to use on older or less powerful computers. It is available with Fedora, Ubuntu, and other Linux distributions.
LXDE The Lightweight X11 Desktop Environment (LXDE) was designed to be a fast-performing, energy-saving desktop environment. Often, LXDE is used on less-expensive devices (such as netbook computers) and on live media (such as a live CD or live USB stick). It is the default desktop for the KNOPPIX live CD distribution. Although LXDE is not included with RHEL, you can try it with Fedora or Ubuntu.
GNOME was originally designed to resemble the MacOS desktop, while KDE was meant to emulate the Windows desktop environment. Because it is the most popular desktop environment, and the one most often used in business Linux systems, most desktop procedures and exercises in this book use the GNOME desktop. Using GNOME, however, still gives you the choice of several different Linux distributions.
Starting with the Fedora GNOME Desktop Live image
A live Linux ISO image is the quickest way to get a Linux system up and running so that you can begin trying it out. Depending on its size, the image can be burned to a CD, DVD, or USB drive and booted on your computer. With a Linux live image, you can have Linux take over the operation of your computer temporarily without harming the contents of your hard drive.
If you have Windows installed, Linux just ignores it and takes control of your computer itself. When you are finished with the Linux live image, you can reboot the computer, pop out the CD or DVD, and go back to running whatever operating system was installed on the hard disk.
To try out a GNOME desktop along with the descriptions in this section, I suggest that you get a Fedora Live DVD (as described in Appendix A). Because a live DVD does all its work from the DVD and in memory, it runs slower than an installed Linux system. Also, although you can change files, add software, and otherwise configure your system, by default, the work you do disappears when you reboot unless you explicitly save that data to your hard drive or external storage.
The fact that changes you make to the live environment go away on reboot is very good for trying out Linux but not that great if you want an ongoing desktop or server system. For that reason, I recommend that if you have a spare computer, you install Linux permanently on that computer's hard disk to use with the rest of this book (as described in Chapter 9).
After you have a live CD or DVD in hand, do the following to get started:
1 Get a computer. If you have a standard PC (32-bit or 64-bit) with a CD/DVD drive, at least 1GB of memory (RAM), and at least a 1GHz processor, you are ready to start. (Just make sure that the image you download matches your computer's architecture—a 64-bit medium does not run on a 32-bit computer. Fedora 31 and RHEL 7 dropped 32-bit support, so you would need older versions of those distributions to run on those older machines.)
2 Start the live CD/DVD. Insert the live CD/DVD or USB drive into your computer and reboot your computer. Depending on the boot order set on your computer, the live image might start up directly from the BIOS (the code that controls the computer before the operating system starts).NOTEIf, instead of the live medium booting, your installed operating system starts up instead, you need to perform an additional step to start the live CD/DVD. Reboot again, and when you see the BIOS screen, look for some words that say something like “Boot Order.” The onscreen instructions may say to press the F12 or F1 key. Press that key immediately from the BIOS screen. Next, you should see a screen that shows available selections. Highlight an entry for CD/DVD or USB drive, and press Enter to boot the live image. If you don't see the drive there, you may need to go into BIOS setup and enable the CD/DVD or USB drive there.
3 Start Fedora. If the selected drive is able to boot, you see a boot screen. For Fedora, with Start Fedora highlighted, press Enter to start the live medium.
4 Begin using the desktop. For Fedora, the live medium lets you choose between installing Fedora or booting it directly from the medium to a GNOME 3 desktop.
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