What is a Linux Shell ��

What
is Linux Shell?

The
shell is the program that acts as a user interface to send commands to the
kernel. 

The kernel then interprets the command and tells the CPU and other
computer hardware how to carry out the particular task. Every time a user logs
in, a shell is started.

Several shells are available for Linux including:

•BASH ( Bourne-Again Shell ) - Most
common shell in Linux. It's Open Source.

•CSH (C Shell) - The C shell's
syntax and usage are very similar to the C programming language.

•KSH (Korn Shell) - Created by David
Korn at AT & T Bell Labs. The Korn Shell also was the base for the

 POSIX
Shell standard specifications.

•TCSH - It is an enhanced but
completely compatible version of the Berkeley UNIX C shell (CSH).

•The Z shell (Zsh) is a Unix shell
that can be used as an interactive login shell and as a command

interpreter for
shell scripting. Zsh is an extended Bourne shell with a large number of
improvements, 

including some features of Bash, ksh, and tcsh.

More detail about shell

•The shell is a user program or it
is an environment provided for user interaction.

•It is a command language
interpreter that executes commands read from the standard input 

device such as
keyboard or from a file.

•The shell gets started when you log
in or open a console (terminal).

•The shell is not part of system
kernel, but uses the system kernel to execute programs, create 

files etc.