Mac OS® X Tiger™ Unleashed

Customizing Your Shell Environment and Storing Data

Variables are a way of addressing bits of the computer memory so that we can store random pieces of information in it. It would be difficult to do much productive work with a computer if all we could store in any location was one particular, predetermined piece of information. Variables give us the ability to name a region X, store whatever value we want in X, and change the value whenever we want. Variables in the shell are used both to hold data to be used in commands and programs written in the shell and to control the behavior of certain aspects of the shell. You've already been introduced peripherally to this second use by way of the PATH variable, which affects where the shell looks to ...