The quantity of use the Linux shell sees is highly dependent on the user. Some Linux buffs couldn't manage without it. They use it to read and compose e-mail, and even to browse the Web (usually using the Mutt and Lynx programs, respectively).
However, most people simply use it to manage files, view text files (like program documentation), and run programs. All kinds of programs—including GUI and command-line—can be started from the shell. As you'll learn in Chapter 29, unlike with Windows, installing a program on SUSE Linux doesn't necessarily mean the program will automatically appear on the K menu. In fact, unless the installation routine is specifically made for the version of Linux you're running, this is unlikely. Therefore, using the shell is a necessity for most people.
Unlike with DOS programs, SUSE Linux programs that describe themselves as "command-line" are rarely designed to run solely via the command-line shell. All programs are like machines that take input at one end and output objects at the other. Where the input comes from and where the output goes to is by no means limited to the command line. Usually, with a command-line program, the input and output are provided via the shell, and the programmer makes special dispensation for this, but this way of working is why GUI programs often make use of what might be considered shell programs. You'll often find that a GUI program designed to, for example, burn CDs, will also require the installation of a command-line program that will actually do the hard work for it.
There's another reason why the shell is used to run programs: you can specify how a particular program runs before starting it. For example, to launch the Kaffeine video player in full-screen mode playing the myvideofile.mpg file, you could type:
kaffeine –f myvideofile.mpg
This saves the bother of starting the program, loading a clip, and then selecting the full-screen option. Once you've typed the command once or twice, you'll be able to remember it for the next time. No matter how much you love the mouse, you'll have to admit that this method of running programs is simply more efficient.
When you get used to using the shell, it's likely you'll have it open most of the time behind your other program windows.