The Korn Shell (KSH) is a Unix and Linux shell that was developed by David Korn at Bell Labs in the early 1980s. It is a command-line interpreter that allows users to execute commands and scripts, and to write and run programs in the shell.
KSH is a popular shell that is included with many Unix and Linux distributions, and is often the default shell on systems that use the Bourne Again Shell (BASH). It is known for its powerful programming features and its compatibility with the Bourne shell (SH), which is one of the original Unix shells.
KSH has a number of features that make it well-suited for programming, such as arrays, variables, control structures (such as if, for, and while statements), and built-in arithmetic and string manipulation functions. It also supports command line editing, history, and aliases, and allows users to customize the behavior of the shell using configuration files.
For more information on KSH, you can consult the KSH manual or online documentation.