Shell

A shell is  command interpreter between user and Unix kernel as well as provides a strong scripting language in UNIX

Following are the different types of Unix shells:

B shell - /bin/sh – This is the default Unix shell for many Unix operating systems .
Bourne shell was written by S. R. Bourne and its more emphasis is to use it as a scripting language rather than an interactive shell .

Some of the features are :

Provided support for environment variables using parameters and exportable variables.
Redirection of program output and error .
Command substitution using back quotes: `command`.
embed a file/commands using input redirector <<
“for ~ do ~ done” loops
“case ~ in ~ esac” for selecting and responding to a data value .

C-shell /bin/csh was designed to provide the interactive features lacking in b shell such as job control and aliasing .

K shell /bin/ksh – was created by David Korn and has features of both B shell and C shell along with some additional features .

Bash – the Bourne again shell was developed by GNU project .It is based on B shell language and has features of C and K shells.

tcsh is the default shell of FreeBSD and its descendants. Essentially it is C shell with programmable command line completion, command-line editing, and a few other features.

Zsh is a shell designed for interactive use and it has many of the useful features of bash, ksh, and tcsh along with many new features.

Unix Shell configuration files :

b shell
—————————————————–
shell prompt : $
executable file : /bin/sh

bash shell
—————————————————–
shell prompt : $
executable file : /bin/bash

csh shell
——————————————————
shell prompt : %
executable file : /bin/csh

ksh
—————————————————–
shell prompt : $
executable file : /bin/ksh

tcsh shell
——————————————————
shell prompt : &
executable file : /bin/tcsh
Read on tcsh shell invocation .

zsh
—————————————————–
shell prompt : $
executable file : zsh