What is a Unix shell?

A Unix shell is the program which reads user input from the command line and executes actions based upon that input.


There are two general families of Unix shells, the Bourne family and the C family.

The Bourne shell was the original Unix shell. The C shell was the first competing Unix shell.

tcsh is an improved variant of the C shell.

The Korn Shell (ksh) and the Bourne Again Shell (bash) are improved variants of the Bourne shell.

Other less popular shells include the zsh, rc, and es shells.

To determine what shells are available on your Unix system, view the contents of the file /etc/shells.

The decision on which shell to use is almost a religious preference, with Bash and tcsh being the current favorites.

Extensive information regarding Unix shells can be found in the Unix shell differences FAQ.


Unix Shells by Example The second edition of Unix Shells by Examples shows off basic commands and utilities in the three most popular Unix shells--C, Bourne, and Korn--with side-by-side examples. The new edition of this book is sure to be a worthy reference for Unix programmers for getting around their favorite shell.

The best thing in this new edition is that the author presents short, effective examples of using basic commands and utilities for each of the three major Unix shells. This comparative approach means that you can use this book on different flavors of Unix and even migrate scripts between different shells. For each shell, the author provides fundamentals, like accessing profiles, command-line histories, and shell programming. "Lab sections" let you develop your skills with short, hands-on exercises for each shell. As in the earlier edition, the author's short examples show you how to perform basic tasks quickly with common switches and options.

Other sections here cover three major Unix utilities: grep (for searching), sed (for editing), and awk (for scripting and reporting). (The reference and tutorial on AWK programming is a notable feature here. There is also good coverage of regular expressions.)

Instead of hunting down information in countless man pages, this book will save you valuable time every day with its efficient format and comparative approach--truly useful features for the beginning and intermediate Unix user.