Chapter 4. Shell Overview

The shell is a program that acts as a buffer between you and the operating system. In its role as a command interpreter , it should (for the most part) act invisibly . It can also be used for simple programming. The shell receives the commands you enter using the Terminal (or a similar program), and decides what to do with it.

This chapter provides a basic overview of the shells included with Mac OS X. Refer to Chapter 5 for specific information about Mac OS X's default user shell, bash .

Earlier versions of Mac OS X used the tcsh shell as the default user shell. However, all that changed with Panther (Mac OS X v 10.3), when Apple switched the default user shell to bash . While many people speculated about the change, the main reason Apple switched to bash is for its Unicode support.