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:

Feature	Bourne	C	TC	Korn	Bash
Aliases	no	yes	yes	yes	yes
Command-line editing	no	no	yes	yes	yes
Advanced pattern matching	no	no	no	yes	yes
Filename completion	no	yes	yes	yes	yes
Directory stacks (pushd and popd)	no	yes	yes	no	yes
History	no	yes	yes	yes	yes
Functions	yes	no	no	Yes	yes
Key binding	no	no	yes	no	yes
Job control	no	yes	yes	yes	yes
Spelling correction	no	no	yes	no	yes
Prompt formatting	no	no	yes	no	yes

 

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.