UNIX shell scripting is one of the techniques used in some configuration management tools, specifically those that can be run on UNIX systems. Similar to Windows Operating systems command.com or cmd.exe, users can direct the operation by entering a command for a shell to execute. Therefore, the UNIX shell provides a user interface for UNIX platforms or similar systems.
The UNIX shell, in a general sense, can act as both a scripting programming language and interactive command language. UNIX system scripts are to be compared to batch files for Windows and MS DOS with file extensions .bat and .cmd. However, there is a new command line that will soon replace cmd.exe. The codename is Monad and its many features are derived from UNIX systems.
These are the following UNIX shell categories: Bourne-like, C Shell-like and historical.
(a) Bourne-like shell (sh) – was developed at Bell Labs by Steve Bourne – distributed first with Version 7 UNIX in 1978 – further classified into four, namely: Almquist shell (or ash used in environments that are resource-constrained), Bourne-again shell (or bash provide a Bourne set functionality superset), Korn shell (or ksh developed also at Bell Labs by David Korn), and Z shell (or zsh most complete shell)
(b) C Shell-like (csh) – written by Bill Joy at the University of California, circa 1979
(c) Historic – Thompson Shell (or sh the very first UNIX shell by Ken Thompson at Bell Laboratories and was distributed from version 1 to 6 from 1971 to 1975) – Marshey Shell (or sh / PWB Shell a version of the Thompson shell as enhanced by John Marshey and other at the Bell Laboratorie and was distributed in circa 1976)