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Command Line Primer

A command-line interface is a way for you to manipulate your computer in situations where a graphical approach is not available. The Terminal application is the Mac OS X gateway to the BSD command-line interface. Each window in Terminal contains a complete execution context, called a shell, that is separate from all other execution contexts. The shell itself is an interactive programming language interpreter, with a specialized syntax for executing commands and writing structured programs, called shell scripts. A shell remains active as long as its Terminal window remains open.

Different shells feature slightly different capabilities and programming syntax. Although you can use any shell of your choice, the examples in this book assume that you are using the standard Mac OS X shell. The standard shell is bash if you are running Mac OS X v10.3 or later and tcsh if you are running an earlier version of the operating system.

The following sections provide some basic information and tips about using the command-line interface more effectively; they are not intended as an exhaustive reference for using the shell environments.

Contents:

Basic Shell Concepts
Frequently Used Commands
Environment Variables
Running Programs

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