From Rosetta Code
Ksh93 is an implementation of UNIX Shell. Other implementations of UNIX Shell.

ksh93 is the original Korn Shell. ksh93 had a major revision during 1993; older versions were ksh88. ksh93 has:

  • lexically scoped variables
  • associative arrays
  • variable name references
  • compound variables
  • discipline functions
  • type variables (see Arithmetic/Complex#UNIX_Shell for an example)
  • arithmetic enhancements (math library functions exposed in ksh)
  • several additional builtin commands