Overview
The shell is the primary user interface to a UNIX system. The concept of the shell was introduced in Chapter 1 along with other key UNIX operating system components: the kernel and the file system. The UNIX environment provides support for many built-in (i.e. Bourne, C, Korn) and third party shells. This chapter provides a brief review of the function of the shell and focuses on the two main ones used with UNIX systems today: the Korn Shell and the C Shell. It goes into greater detail about the unique features of each shell and provides information on how to become more efficient by using custom prompts, aliases, history, and re-execution of commands.