Cisco ASA and PIX Firewall Handbook

Chapter 25. Harnessing the Power of the Shell

What You'll Learn in This Chapter:

• How to manipulate text and numbers from the command line

• How to organize shell commands into a shell script

• How to use variables inside a shell script to perform complex tasks

• How to turn shell scripts into executable commands that accept arguments

• How to control the flow of the shell script based on user input

This chapter represents the last of our Linux command-line training lessons. In it, you learn many of the more advanced techniques for interacting with the shell. This chapter is not exhaustive by any means; the focus is on basic skills and on whetting your appetite for more, in hopes that you'll study more man pages or even read a more in-depth book about the very powerful Linux shell.

Because this chapter is all about shell scripts, be prepared to spend a lot of time working inside a text editor, such as vi or emacs. If you've forgotten how these editors work or don't feel familiar with them any longer, you might want to review Chapter 20, "Creating, Editing, and Saving Text Files," before continuing.