ksh93:
ksh93: The KornShell language and interactive shell were designed by
ksh93: David G. Korn at AT&T Bell Laboratories. Besides offering a powerful
ksh93: interactive shell, it also offers a robust programming language with
ksh93: such features as associative arrays and built in integer math
ksh93: operations. ksh is an excellent choice for system administration
ksh93: scripts and for everyday interactive use.
ksh93: 
ksh93: The site for KornShell 93u+m is https://github.com/ksh93/ksh
ksh93: