Bash

Bash is a Unix shell written for the GNU Project. The name of the actual executable is bash. Its name is an acronym for Bourne-again shell, a pun on the name of the Bourne shell (sh) (i.e. "Bourne again" or "born again"), an early and important Unix shell written by Stephen Bourne and distributed with Version 7 Unix circa 1978. Bash was created in 1987 by Brian Fox. In 1990 Chet Ramey became the primary maintainer.

Bash is the default shell on most Linux systems as well as on Mac OS X and it can be run on most Unix-like operating systems. It has also been ported to Microsoft Windows within the Cygwin POSIX emulation environment for Windows, to MS-DOS by the DJGPP project and to Novell NetWare. Released under the GNU General Public License, Bash is free software.