Comparison of shells

Initially, the Unix OS used a shell program called the Bourne shell. Then, eventually, many more shell programs were developed for different flavors of Unix. The following is some brief information about different shells:

• sh—Bourne shell
• csh—C shell
• ksh—Korn shell
• tcsh—enhanced C shell
• bash—GNU Bourne Again shell
• zsh—extension to bash, ksh, and tcsh
• pdksh—extension to ksh

A brief comparison of various shells is presented in the following table:

What we see here is that, generally, the syntax of all these shells is 95% similar.
In this book, we are going to follow Bash shell programming.