Bash (Bourne Again Shell ) is the free version of the Bourne shell distributed with Linux and GNU operating systems. Bash is similar to the original, but has added features such as command line editing.
Created to improve on the earlier sh shell, Bash includes features from the Korn shell and the C shell. Bash is intended to conform to the shell standard specified as part of IEEE POSIX. A command language script written for the sh shell will also run in the bash shell.
The full name is sometimes written as "Bourne Again SHell," the capitalized "Hell" referring to the difficulty some people have with it.