Learning Red Hat Linux, Third Edition

Chapter 13. Advanced Shell Usage and Shell Scripts

Like an MS-DOS prompt window, the Unix shell is a command interpreter that lets you issue and execute commands. By means of the shell, you use and control your system. If you’re accustomed to the point-and-click world of graphical user interfaces, you may question the value of learning to use the Linux shell. Many users initially find the shell cumbersome, and some retreat to the familiar comfort of the graphical user interface (GUI), avoiding the shell whenever possible. However, as this chapter explains, the shell unlocks the true power of Linux.

The Power of the Unix Shell

While it’s true that the shell is an older style of interacting with a computer than the GUI, the graphical user interface is actually the more primitive interface. The GUI is easy to learn and widely used, but the shell is vastly more sophisticated. Using a GUI is somewhat like communicating in American Indian sign language. If your message is a simple one, like “We come in peace,” you can communicate it by using a few gestures. However, if you attempted to give Lincoln’s Gettysburg address—a notably short public discourse—you’d find your task quite formidable.^[5]

The designer of a program that provides a GUI must anticipate all the possible ways in which the user will interact with the program and provide ways to trigger the appropriate program responses by means of pointing and clicking. Consequently, the user is constrained to working only in predicted ...