Earlier this year I discussed trying the KornShell as my daily driver, but I didn’t know the difference between the major versions. Perhaps this brief summary post might be useful to someone.
ksh93is the evolution of the canonical ksh88 by David Korn and Morris Bolsky at AT&T. It was originally proprietary, but has since been released into the public domain. It’s actively maintained, and shipped with macOS. It’s officially spelled KornShell.
pdkshis the Public Domain Korn Shell, released in response to ksh88 being proprietary. NetBSD’s default install includes this variant, and it was the first Korn Shell I used. This, and all its other derivatives, are spelled Korn Shell with a space.
mkshis the MirBSD/MirOS Korn Shell. Based on
pdksh. The landing page is outdated, but it’s still actively maintained.
tckshis the TENEX Sea Kucumber Shell. Blatantly made up by me.
okshis the Portable OpenBSD Korn Shell. Based on
pdksh, with enhancements. I use this variant now, for a few delightful reasons I will soon blog about.