<s>
KornShell	B-Language
(	O
ksh	O
)	O
is	O
a	O
Unix	B-Application
shell	I-Application
which	O
was	O
developed	O
by	O
David	O
Korn	O
at	O
Bell	O
Labs	O
in	O
the	O
early	O
1980s	O
and	O
announced	O
at	O
USENIX	B-Operating_System
on	O
July	O
14	O
,	O
1983	O
.	O
</s>
<s>
The	O
initial	O
development	O
was	O
based	O
on	O
Bourne	B-Device
shell	I-Device
source	O
code	O
.	O
</s>
<s>
Other	O
early	O
contributors	O
were	O
Bell	O
Labs	O
developers	O
Mike	O
Veach	O
and	O
Pat	O
Sullivan	O
,	O
who	O
wrote	O
the	O
Emacs	B-Application
and	O
vi-style	O
line	O
editing	O
modes	O
 '	O
code	O
,	O
respectively	O
.	O
</s>
<s>
KornShell	B-Language
is	O
backward-compatible	O
with	O
the	B-Device
Bourne	I-Device
shell	I-Device
and	O
includes	O
many	O
features	O
of	O
the	O
C	B-Operating_System
shell	I-Operating_System
,	O
inspired	O
by	O
the	O
requests	O
of	O
Bell	O
Labs	O
users	O
.	O
</s>
<s>
KornShell	B-Language
complies	O
with	O
POSIX.2	O
,	O
Shell	O
and	O
Utilities	O
,	O
Command	O
Interpreter	O
(	O
IEEE	O
Std	O
1003.2-1992	O
.	O
)	O
</s>
<s>
Major	O
differences	O
between	O
KornShell	B-Language
and	O
the	O
traditional	O
Bourne	B-Device
shell	I-Device
include	O
:	O
</s>
<s>
KornShell	B-Language
was	O
originally	O
proprietary	B-Application
software	I-Application
.	O
</s>
<s>
In	O
2000	O
the	O
source	O
code	O
was	O
released	O
under	O
a	O
license	O
particular	O
to	O
AT&T	O
,	O
but	O
since	O
the	O
ksh93q	O
release	O
in	O
early	O
2005	O
it	O
has	O
been	O
licensed	O
under	O
the	O
Eclipse	B-License
Public	I-License
License	I-License
.	O
</s>
<s>
KornShell	B-Language
is	O
available	O
as	O
part	O
of	O
the	O
AT&T	O
Software	O
Technology	O
(	O
AST	O
)	O
Open	O
Source	O
Software	O
Collection	O
.	O
</s>
<s>
As	O
KornShell	B-Language
was	O
initially	O
only	O
available	O
through	O
a	O
proprietary	B-Application
license	I-Application
from	O
AT&T	O
,	O
a	O
number	O
of	O
free	B-Application
and	O
open	O
source	O
alternatives	O
were	O
created	O
.	O
</s>
<s>
The	O
functionality	O
of	O
the	O
original	O
KornShell	B-Language
,	O
,	O
was	O
used	O
as	O
a	O
basis	O
for	O
the	O
standard	O
POSIX.2	O
,	O
Shell	O
and	O
Utilities	O
,	O
Command	O
Interpreter	O
(	O
IEEE	O
Std	O
1003.2-1992	O
.	O
)	O
</s>
<s>
is	O
maintained	O
on	O
GitHub	B-Application
.	O
</s>
<s>
As	O
"	O
Desktop	O
KornShell	B-Language
"	O
(	O
)	O
,	O
is	O
distributed	O
as	O
part	O
of	O
the	O
Common	B-Application
Desktop	I-Application
Environment	I-Application
.	O
</s>
<s>
This	O
version	O
also	O
provides	O
shell-level	O
mappings	O
for	O
Motif	B-Application
widgets	O
.	O
</s>
<s>
It	O
was	O
intended	O
as	O
a	O
competitor	O
to	O
Tcl/Tk	B-Application
.	O
</s>
<s>
The	O
original	O
KornShell	B-Language
,	O
,	O
became	O
the	O
default	O
shell	O
on	O
AIX	B-Application
in	O
version	O
4	O
,	O
with	O
ksh93	B-Language
being	O
available	O
separately	O
.	O
</s>
<s>
UnixWare	B-Operating_System
7	O
includes	O
both	O
and	O
.	O
</s>
<s>
The	O
default	O
Korn	B-Language
shell	I-Language
is	O
,	O
which	O
is	O
supplied	O
as	O
,	O
and	O
the	O
older	O
version	O
is	O
available	O
as	O
.	O
</s>
<s>
UnixWare	B-Operating_System
also	O
includes	O
when	O
CDE	B-Application
is	O
installed	O
.	O
</s>
<s>
The	O
ksh93	B-Language
distribution	O
underwent	O
a	O
less	O
stable	O
fate	O
after	O
the	O
authors	O
left	O
AT&T	O
around	O
2012	O
at	O
stable	O
version	O
ksh93u+	O
.	O
</s>
<s>
ksh2020	O
was	O
released	O
as	O
a	O
"	O
major	O
release	O
for	O
several	O
reasons	O
"	O
such	O
as	O
removal	O
of	O
EBCDIC	B-Language
support	O
,	O
dropped	O
support	O
for	O
binary	O
plugins	O
written	O
for	O
ksh93u+	O
and	O
removal	O
of	O
some	O
broken	O
math	O
functions	O
,	O
was	O
released	O
by	O
AT&T	O
,	O
but	O
has	O
never	O
been	O
maintained	O
or	O
supported	O
by	O
them	O
(	O
not	O
even	O
on	O
its	O
initial	O
release	O
date	O
)	O
.	O
</s>
<s>
Besides	O
the	O
primary	O
major	O
contributing	O
corporations	O
(	O
listed	O
above	O
)	O
,	O
some	O
companies	O
have	O
contributed	O
free	B-Application
resources	O
to	O
the	O
development	O
of	O
KSH	O
.	O
</s>
<s>
There	O
are	O
several	O
forks	B-Application
and	O
clones	O
of	O
KornShell	B-Language
:	O
</s>
<s>
–	O
a	O
fork	B-Application
of	O
included	O
as	O
part	O
of	O
CDE	B-Application
.	O
</s>
<s>
–	O
a	O
fork	B-Application
of	O
that	O
provides	O
access	O
to	O
the	O
Tk	B-Application
widget	B-Library
toolkit	I-Library
.	O
</s>
<s>
–	O
a	O
port	O
of	O
OpenBSD	B-Operating_System
's	O
variant	O
of	O
KornShell	B-Language
,	O
intended	O
to	O
be	O
maximally	O
portable	O
across	O
operating	O
systems	O
.	O
</s>
<s>
It	O
was	O
used	O
as	O
the	O
default	O
shell	O
in	O
DeLi	O
Linux	B-Application
7.2	O
.	O
</s>
<s>
–	O
a	O
Linux	B-Application
port	O
of	O
OpenBSD	B-Operating_System
's	O
variant	O
of	O
KornShell	B-Language
,	O
with	O
minimal	O
changes	O
.	O
</s>
<s>
–	O
a	O
free	B-Application
implementation	O
of	O
the	O
KornShell	B-Language
language	O
,	O
forked	O
from	O
OpenBSD	B-Operating_System
.	O
</s>
<s>
It	O
was	O
originally	O
developed	O
for	O
MirOS	B-Application
BSD	I-Application
and	O
is	O
licensed	O
under	O
permissive	B-License
(	O
though	O
not	O
public	B-Application
domain	I-Application
)	O
terms	O
;	O
specifically	O
,	O
the	B-Operating_System
MirOS	I-Operating_System
Licence	I-Operating_System
.	O
</s>
<s>
–	O
an	O
AmigaOS	B-Application
variant	O
that	O
provides	O
several	O
Amiga-specific	O
features	O
,	O
such	O
as	O
ARexx	B-Operating_System
interoperability	O
.	O
</s>
<s>
In	O
this	O
tradition	O
MorphOS	B-Operating_System
uses	O
in	O
its	O
SDK	O
.	O
</s>
<s>
MKS	O
Inc.	O
'	O
s	O
MKS	O
Korn	B-Language
shell	I-Language
–	O
a	O
proprietary	B-Application
implementation	O
of	O
the	O
KornShell	B-Language
language	O
from	O
Microsoft	O
Windows	O
Services	O
for	O
UNIX	B-Application
(	O
SFU	O
)	O
up	O
to	O
version	O
2.0	O
;	O
according	O
to	O
David	O
Korn	O
,	O
the	O
MKS	O
Korn	B-Language
shell	I-Language
was	O
not	O
fully	O
compatible	O
with	O
KornShell	B-Language
in	O
1998	O
.	O
</s>
<s>
In	O
SFU	O
version	O
3.0	O
Microsoft	O
replaced	O
the	O
MKS	O
Korn	B-Language
shell	I-Language
with	O
a	O
new	O
POSIX.2-compliant	O
shell	O
as	O
part	O
of	O
Interix	B-Operating_System
.	O
</s>
<s>
KornShell	B-Language
is	O
included	O
in	O
UWIN	B-Application
,	O
a	O
Unix	B-Application
compatibility	O
package	O
by	O
David	O
Korn	O
.	O
</s>
<s>
/bin/sh	B-Device
in	O
Doug	O
Gwyn	O
's	O
(	O
US	O
Army	O
BRL	O
)	O
System	O
V	O
on	O
BSD	O
package	O
included	O
Ron	O
Natalie	O
's	O
version	O
of	O
the	O
SVR2	O
/bin/sh	B-Device
that	O
had	O
both	O
job	B-Operating_System
control	I-Operating_System
and	O
command	O
line	O
editing	O
.	O
</s>
<s>
This	O
was	O
subsequently	O
the	O
/bin/sh	B-Device
that	O
shipped	O
with	O
all	O
the	O
CMU	O
Mach-derived	O
systems	O
.	O
</s>
