GNU Bash (Bourne again shell) is a Unix shell and command language written by Brian Fox for the GNU Project as a free software replacement for the Bourne shell. Released in 1989, it has been distributed widely as the shell for the GNU operating system and as a default shell on Linux and OS X. Microsoft announced during the 2016 Build Conference that Windows 10 has added a Linux subsystem that fully supports Bash and other Ubuntu binaries running natively in Windows. In the past, and currently, it has also ported to Microsoft Windows and distributed with Cygwin and MinGW, to DOS by the DJGPP project, to Novell NetWare and to Android via various terminal emulation applications. In the late 1990s, Bash was a minor player among multiple commonly used shells; at present Bash has overwhelming favor.
This is an sh-compatible shell that incorporates useful features from the Korn shell (ksh) and the C shell (csh). It's intended to conform to the IEEE POSIX P1003.2/ISO 9945.2 Shell and Tools standard. It offers functional improvements over sh for both programming and interactive use. In addition, most sh scripts can be run by Bash without modification.Since 2010, there has been a close collaboration between FSF/GNU and FreeWear, that donate a portion of the sales of BASH materials in this website. This BASH donations go to GNU.
More information: http://www.fsf.org/