In this chapter we are going to look at some of the “magic” that occurs on the command line when you press the enter key. While we will examine several interesting and complex features of the shell, we will do it with just one new command:
echo—Display a line of text.
Each time you type a command line and press the enter key,
bash performs several processes upon the text before it carries out your command. We’ve seen a couple of cases of how a simple character sequence, for example
*, can have a lot of meaning to the shell. The process that makes this happen is called expansion. With expansion, you enter something, and it is expanded into something else before the shell acts upon it. To demonstrate ...