The KornShell language was designed and developed by David G. Korn at AT&T Bell Laboratories. It is an interactive command language that provides access to the UNIX system and to many other systems, on the many different computers and workstations on which it is implemented. ksh has the functionality of other scripting languages such as awk, icon, perl, rexx, and tcl. For this and many other reasons, ksh is a much better scripting language than any of the other popular shells. The code size for ksh is larger than the Bourne shell or C shell programs. The revised version is even larger. In spite of its increased size, ksh provides better performance. You can write programs to run faster with ksh than with either the Bourne shell or the C shell, sometimes an order of magnitude faster. ksh has evolved and matured with extensive user feedback. It has been used by many thousands of people at AT&T since 1982, and at many other companies and universities.