Unix Shell

                                    A Unix shell is a command line interpreter that provides a traditional user interface for the Unix operating system and for Unix-like systems. Users direct the operation of the computer by entering commands as text for a command line interpreter to execute, or by creating text scripts of one or more such commands. Users typically interact with a Unix shell using a terminal emulator, however, direct operation via serial hardware connections, or networking session, are common for server systems.
The most influential Unix shells have been the Bourne Shell and the C shell. These shells have both been used as the coding base and model for many derivative and work-alike shells with extended feature sets.

                            The Bourne shell, sh, was written by Stephen Bourne at AT&T as the original Unix command line interpreter; it introduced the basic features common to all the Unix shells, including piping, here documents, command substitution, variables, for condition-testing and looping and file name wild carding. The language, including the use of a reversed keyword to mark the end of a block, was influenced by ALGOL 68.

C shell

The C shell was developed by Bill Joy for the Berkeley Software Distribution(BSD), a line of Unix operating systems derived from Unix and developed at the University of California, Berkeley. It was originally derived from the 6th Edition Unix shell, with its syntax modeled after the C-programming language. The C shell is used primarily for interactive terminal use, and less frequently for scripting and operating system control. It has interactive keyboard shortcuts in form of special control-key sequences for special effects such as job control.