Editing KornShell (section)

==History==
[[File:Korn Shell running on SUA.png|thumb|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]].<ref name="ksh93epl" /> 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 {{mono|pdksh}}, {{mono|mksh}}, [[Bash (Unix shell)|Bash]], and [[Z shell]].

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

Some vendors still ship their own versions of the older {{mono|ksh88}} variant, sometimes with extensions. {{mono|ksh93}} is maintained on [[GitHub]].<ref>{{cite web|url=https://github.com/att/ast|title=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..|date=10 December 2018|access-date=10 December 2018|website=Github.com}}</ref>

As "Desktop KornShell" ({{mono|dtksh}}), {{mono|ksh93}} is distributed as part of the [[Common Desktop Environment]].<ref name="RosenblattRobbins2002">{{cite book|author1=Bill Rosenblatt|author2=Arnold Robbins|title=Learning the Korn Shell|url=https://books.google.com/books?id=5nMCY272chUC&pg=PR8|year=2002|publisher=O'Reilly |isbn=978-0-596-00195-7|pages=viii–ix|edition=2}}</ref> This version also provides shell-level mappings for [[Motif (software)|Motif]] widgets. It was intended as a competitor to [[Tcl]]/[[Tk (software)|Tk]].<ref name="Pendergrast1995">{{cite book|first=J. Stephen |last=Pendergrast|title=Desktop KornShell graphical programming|url=https://books.google.com/books?id=O6xQAAAAMAAJ|year=1995|publisher=Addison-Wesley|isbn=978-0-201-63375-7|page=359}}</ref>

The original KornShell, {{mono|ksh88}}, became the default shell on [[AIX]] in version 4,<ref name="CannonTrent1999">{{cite book|author1=Casey Cannon|author2=Scott Trent|author3=Carolyn Jones|title=Simply AIX 4.3|year=1999|publisher=Prentice Hall |isbn=978-0-13-021344-0|page=21}}</ref><ref>{{cite web|url=https://www.ibm.com/support/knowledgecenter/ssw_aix_61/eos/eos.htm?origURL=api/redirect/aix/v6r1/topic/com.ibm.aix.cmds/doc/aixcmds5/sh.htm|title=IBM Knowledge Center|publisher=IBM|access-date=10 December 2018}}</ref> with ksh93 being available separately.<ref>{{cite web|url=https://www.ibm.com/support/knowledgecenter/ssw_aix_61/eos/eos.htm?origURL=api/redirect/aix/v6r1/topic/com.ibm.aix.baseadmn/doc/baseadmndita/korn_shell_enhanced.htm|title=IBM Knowledge Center|publisher=IBM|access-date=10 December 2018}}</ref>

[[UnixWare]] 7 includes both {{mono|ksh88}} and {{mono|ksh93}}. The default Korn shell is {{mono|ksh93}}, which is supplied as {{mono|/usr/bin/ksh}}, and the older version is available as {{mono|/usr/bin/ksh88}}.<ref name="UW714doc">{{cite web|url=http://uw714doc.sco.com/en/DIFFS/UNIX95_Conformance.html#ksh-93_vs_ksh-88|title=UNIX95 conformance|website=Uw714doc.sco.com|access-date=10 December 2018}}</ref> UnixWare also includes {{mono|dtksh}} when [[Common Desktop Environment|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'''<ref name="ksh2020">{{cite web |title=ksh2020 |url=https://github.com/ksh2020/ksh |website=GitHub |date=26 Feb 2021 |language=en}}</ref> in the fall of 2019. That initial release (although fixing several prior stability issues) introduced breakage and compatibility issues.<ref>{{cite web |title=ksh2020 changelog |url=https://github.com/att/ast/blob/ksh2020/CHANGELOG.md |website=GitHub |date=29 May 2020 |language=en}}</ref> 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.<ref>{{cite web |title=Rewinding this repo and encouraging community · Issue #1466 · att/ast |url=https://github.com/att/ast/issues/1466 |website=GitHub |language=en}}</ref><ref>{{cite web |title= segfault with extended globs · #1464 · att/ast |url=https://github.com/att/ast/issues/1464#issuecomment-581159703 |website=GitHub |language=en}}</ref> '''ksh2020''' <ref>{{Cite web|title= 2020.0.0: Stable release of ksh-2020.0.0 |url=https://github.com/att/ast/releases/tag/2020.0.0|access-date=2021-01-29|quote=Note: ksh2020 is not maintained or supported|website=GitHub|language=en}}</ref> was released as a "major release for several reasons"<ref>{{Cite web|title=ksh 2020.0.0 CHANGELOG|url=https://github.com/att/ast/blob/2020.0.0/CHANGELOG.md |date=2021-01-29|website=GitHub|language=en}}</ref> such as removal of [[EBCDIC]] support, dropping support for binary plugins written for '''ksh93u+''' and removal of some broken math functions, but has never been maintained or supported by AT&T (not even on its initial release date). The '''ksh2020''' source code has received no commits since February 2020 and it was archived read only in October 2021.<ref name="ksh2020"/>

Following the issues with the '''ksh2020''' branch and its abandonment, a new repository was created in May 2020 for the '''ksh93u+m''' branch, based on the last stable AT&T release ('''ksh93u+''' 2012-08-01) where bugfix development actively continues.<ref>{{cite web |title=ksh '''93u+m''' |url=https://github.com/ksh93/ksh |website=GitHub|date=17 November 2021 }}</ref>