What is Ksh?
Ksh, also known as Korn Shell, is an interactive command language for Unix as well as for other systems. The Korn Shell provides a powerful programming language for developing applications. Ksh aims to allow developers to write applications faster than in Bourne shell and C Shell with features that enhance productivity. Ksh incorporates features from both Bourne and C shell and also has some of its own exclusive features. Some of the many Ksh features are improved performance, arithmetic, arrays, as well as substring and pattern matching capabilities.
The name of the actual executable is ksh at:
Enabling Ksh as default
You can change your shell in the panel at (Panel > 'Users' > 'Manage Users').