Korn Shell

Korn Shell, or ksh, is the creation of David Korn at AT&T. This shell combines compatible with::Bourne Shell syntax with a command-line editor, command history, tilde expansion, arithmetic expressions, arrays, coprocesses and several more features. Korn Shell has influenced many later shells; Public Domain Korn Shell and Z Shell clone several features, and the X/Open and POSIX standards take a few features from Korn Shell. David Korn continues to maintain ksh93, the original implementation.

Korn Shell is an implementation of UNIX Shell. Other implementations of UNIX Shell.

AT&T freed ksh93 during 2000, using an open-source license. For many years before that, the original Korn Shell was not free; it was only part of AT&T System V and some commercial Unix variants. Therefore, ksh in some systems is not David Korn's shell, but is some other shell, perhaps pdksh or mksh.

Which Korn Shell do I have?

Start ksh and run

<lang bash>$ echo $KSH_VERSION</lang>

• If the output looks like Version JM 93u 2011-02-08, then you have ksh93.
• If the output looks like @(#)PD KSH v5.2.14 99/07/13.2, then you have pdksh.
• If the output looks like (what?), then you have mksh.
• A zsh invoked as ksh sets ZSH_VERSION, not KSH_VERSION.

Links

• Home Page For The KornShell Command And Programming Language
• wp:korn shell