Bourne Shell - Descendants

Descendants

The Korn shell (ksh) written by David Korn, was a middle road between the Bourne shell and the C shell. Its syntax was chiefly drawn from the Bourne shell, while its job control features resembled those of the C shell. The functionality of the original Korn Shell (known as ksh88 from the year of its introduction) was used as a basis for the POSIX shell standard. A newer version, ksh93, has been open source since 2000 and is used on some Linux distributions. There is also a clone of ksh88 known as pdksh, and this is the default shell for all users of OpenBSD.

Bash (the Bourne-Again shell) was later developed for the GNU project. Bash incorporates features from the Bourne shell, csh, and ksh. Bash is the default shell for OS X, Cygwin, and most Linux distributions.

rc was created at Bell Labs by Tom Duff as a replacement for sh for Version 10 Unix. It is the default shell for Plan 9 from Bell Labs. It has been ported to UNIX as part of Plan 9 from User Space.

Due to copyright issues surrounding the Bourne Shell as it was used in historic CSRG BSD releases, Kenneth Almquist developed a clone of the Bourne Shell, known by some as the Almquist Shell and available under the BSD license, which is in use today on some BSD descendants and in low-memory situations. The Almquist Shell was ported to Linux, and the port renamed the Debian Almquist shell, or dash. This shell provides much faster execution of standard sh scripts with a smaller memory footprint than its more common counterpart, bash. Its use tends to expose bashisms – bash-centric assumptions made in scripts meant to run on sh.