Original author(s)David Korn
Initial release1983; 40 years ago (1983)[1][2]
Final release
93u+ / August 1, 2012; 10 years ago (2012-08-01)
Preview release
93v- / December 24, 2014; 8 years ago (2014-12-24)
Written inC
Operating systemUnix and Unix-like (e.g. Linux and macOS; also works in Windows 10[3])
Available inEnglish
TypeUnix shell
Developer(s)Kurtis Rader, Siteshwar Vashisht, community
Final release
2020 / October 10, 2019; 3 years ago (2019-10-10)
LicenseEclipse Public License
Developer(s)Martijn Dekker, Johnothan King, hyenias
Stable release
1.0.4 / October 21, 2022; 3 months ago (2022-10-21)
LicenseEclipse Public License

KornShell (ksh) is a Unix shell which was developed by David Korn at Bell Labs in the early 1980s and announced at USENIX on July 14, 1983.[1][2] The initial development was based on Bourne shell source code.[7] Other early contributors were Bell Labs developers Mike Veach and Pat Sullivan, who wrote the Emacs and vi-style line editing modes' code, respectively.[8] KornShell is backward-compatible with the Bourne shell and includes many features of the C shell, inspired by the requests of Bell Labs users.


KornShell complies with POSIX.2, Shell and Utilities, Command Interpreter (IEEE Std 1003.2-1992.) Major differences between KornShell and the traditional Bourne shell include:


Korn Shell running on Windows Services for UNIX
Korn Shell running on Windows Services for UNIX

KornShell was originally proprietary software. In 2000 the source code was released under a license particular to AT&T, but since the ksh93q release in early 2005 it has been licensed under the Eclipse Public License.[4] KornShell is available as part of the AT&T Software Technology (AST) Open Source Software Collection. As KornShell was initially only available through a proprietary license from AT&T, a number of free and open source alternatives were created. These include pdksh, mksh, bash, and zsh.

The functionality of the original KornShell, ksh88, was used as a basis for the standard POSIX.2, Shell and Utilities, Command Interpreter (IEEE Std 1003.2-1992.)

Some vendors still ship their own versions of the older ksh88 variant, sometimes with extensions. ksh93 is maintained on GitHub.[10]

As "Desktop KornShell" (dtksh), ksh93 is distributed as part of the Common Desktop Environment.[11] This version also provides shell-level mappings for Motif widgets. It was intended as a competitor to Tcl/Tk.[12]

The original KornShell, ksh88, became the default shell on AIX in version 4,[13][14] with ksh93 being available separately.[15]

UnixWare 7 includes both ksh88 and ksh93. The default Korn shell is ksh93, which is supplied as /usr/bin/ksh, and the older version is available as /usr/bin/ksh88.[16] UnixWare also includes dtksh when CDE is installed.

The ksh93 distribution underwent a less stable fate after the authors left AT&T around 2012 at stable version ksh93u+. The primary authors continued working on a ksh93v- beta branch until around 2014. That work was eventually taken up primarily by Red Hat in 2017 (due to customer requests) and resulted in the eventual initial release of ksh2020[17] in the Fall of 2019. That initial release (although fixing several prior stability issues) introduced some minor breakage and compatibility issues.[18] In March 2020, AT&T decided to roll back the community changes, stash them in a branch, and restart from ksh93u+, as the changes were too broad and too ksh-focused for the company to absorb into a project in maintenance mode.[19][20] Bugfix development continues on the ksh93u+m branch, based on the last stable AT&T release (ksh93u+ 2012-08-01).[21] ksh2020 [22] was released as a "major release for several reasons"[23] such as removal of EBCDIC support, dropped support for binary plugins written for ksh93u+ and removal of some broken math functions, was released by AT&T, but has never been maintained or supported by them (not even on its initial release date).

Primary contributions to the main software branch

For the purposes of the lists below, the main software branch of KSH is defined as the original program, dating from July 1983, up and through the release of KSH2020 in late 2019. Continuing development of follow-on versions (branches) of KSH have split into different groups starting in 2020 and are not elaborated on below.

Primary individual contributors

The following are listed in a roughly ascending chronological order of their contributions:

Integration consultant

Primary corporate contributors

The following are listed in a roughly ascending chronological order of their contributions:

Donated corporate resources

Besides the primary major contributing corporations (listed above), some companies have contributed free resources to the development of KSH. These are listed below (alphabetically ordered):


There are several forks and clones of KornShell:

See also


  1. ^ a b Ron Gomes (Jun 9, 1983). "Toronto USENIX Conference Schedule (tentative)". Newsgroupnet.usenix. Retrieved Dec 29, 2010.
  2. ^ a b Guy Harris (Oct 10, 1983). "csh question". Newsgroupnet.flame. Retrieved Dec 29, 2010.
  3. ^ "Korn Shell Launcher for Windows Subsystem for Linux « Musings". blog.fpmurphy.com. Retrieved 2021-01-29.
  4. ^ a b "ast-open package". AT&T Research. n.d. Archived from the original on October 1, 2015. Retrieved December 19, 2022.
  5. ^ a b "MirBSD Korn Shell". Mirbsd.org. Retrieved 10 December 2018.
  6. ^ Korn, David G. (October 26, 1994), "ksh - An Extensible High Level Language", Proceedings of the USENIX 1994 Very High Level Languages Symposium, USENIX Association, retrieved February 5, 2015, Instead of inventing a new script language, we built a form entry system by modifying the Bourne shell, adding built-in commands as necessary.
  7. ^ Bolsky, Morris I.; Korn, David G. (1989). "Acknowledgements". The KornShell Command and Programming Language. Englewood Cliffs, NJ: Prentice Hall. pp. xii. ISBN 0-13-516972-0.
  8. ^ "traditional Bourne shell family / history and development". In-ulm.de. Retrieved 10 December 2018.
  9. ^ "This is the AT&T Software Technology ast software download site from AT&T Research. The AT&T AST OpenSource Software Collection provides an overview and Practical Reusable UNIX Software." Github.com. 10 December 2018. Retrieved 10 December 2018.
  10. ^ Bill Rosenblatt; Arnold Robbins (2002). Learning the Korn Shell (2 ed.). O'Reilly Media, Inc. pp. viii–ix. ISBN 978-0-596-00195-7.
  11. ^ J. Stephen Pendergrast (1995). Desktop KornShell graphical programming. Addison-Wesley. p. 359. ISBN 978-0-201-63375-7.
  12. ^ Casey Cannon; Scott Trent; Carolyn Jones (1999). Simply AIX 4.3. Prentice Hall PTR. p. 21. ISBN 978-0-13-021344-0.
  13. ^ "IBM Knowledge Center". Ibm.com. Retrieved 10 December 2018.
  14. ^ "IBM Knowledge Center". Ibm.com. Retrieved 10 December 2018.
  15. ^ "UNIX95 conformance". Uw714doc.sco.com. Retrieved 10 December 2018.
  16. ^ "ksh2020". GitHub. 26 Feb 2021.
  17. ^ "ksh2020 changelog". GitHub. 29 May 2020.
  18. ^ "Rewinding this repo and encouraging community · Issue #1466 · att/ast". GitHub.
  19. ^ "segfault with extended globs · #1464 · att/ast". GitHub.
  20. ^ "ksh 93u+m". GitHub. 17 November 2021.
  21. ^ "2020.0.0: Stable release of ksh-2020.0.0". GitHub. Retrieved 2021-01-29. Note: ksh2020 is not maintained or supported
  22. ^ "ksh 2020.0.0 CHANGELOG". GitHub. 2021-01-29.
  23. ^ "oksh at GitHub". GitHub. 1 August 2020.
  24. ^ "loksh at GitHub". GitHub. 15 October 2021.
  25. ^ "5.11. The PDKSH to MKSH transition". Archived from the original on 2014-07-28. Retrieved 2014-07-28.
  26. ^ "Aminet - util/Shell/SKsh21.LZH".
  27. ^ "David Korn Tells All". Slashdot. Retrieved 2009-10-22.
  28. ^ "Jerry Feldman — USENIX NT/LISA NT conference attendee". Lists.blu.org. Retrieved 2009-10-22.
  29. ^ "Windows Services for UNIX Version 3.0". Technet.microsoft.com. Retrieved 2009-10-22.
  30. ^ Anatole Olczak (2001). The Korn shell: Unix and Linux programming manual. Addison-Wesley Professional. p. 4. ISBN 978-0-201-67523-8.

Further reading