Korn shell

A UNIX shell developed by David G. Korn at Bell Labs. It combines the best features of the Bourne shell and the C shell but also adds a lot of the functionality commonly found in scripting languages. As of the 1993 release, ksh was 100% Bourne shell compatible. This release was also distributed under an open source-style license. I don't know a lot about licenses, so I couldn't tell you the strengths and weaknesses of Korn shell's license.

This shell includes a whole pile of features. It really is like a high-level programming language. Its features include:

• Command completion
• vi and Emacs editing modes
• Built-in menu selection capabilities
• Support for floating-point and integer arithmetic up to base 64
• Support for the functions found in math.h
• Substring operators that provide substitutes for things like sed, awk, cut, grep, and others
• Arrays and associative arrays (hashes)
• Variable references
• Support for shell debugging
• A real restricted shell

This is just a small set of the Korn shell's features. It is now available on Linux, in addition to the wide variety of UNIX platforms. It also lacks many of the annoying bugs found in Bash. Try it for youself and see just how enjoyable shell programming can be.