Bash is a Unix shell written for the GNU Project. Its name is an acronym for Bourne-Again SHell — a pun (Bourne again / born again) on the Bourne shell (sh), which was an early, important Unix shell. The Bourne shell was the shell distributed with Version 7 Unix, circa 1978. The original Bourne shell was written by Stephen Bourne, then a researcher at Bell Labs. The Bash shell was written 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 Tiger, and it can be run on most Unix-like operating systems. It has also been ported to Microsoft Windows by the Cygwin project and to MS-DOS by the DJGPP project.