1ksh93u+ is the 2012-08-01 (stable) version of the KornShell Language 2described in "The KornShell Command and Programming Language," by 3Morris Bolsky and David Korn of AT&T Bell Laboratories. The KornShell 4is a shell programming language, which is upward compatible with "sh" 5(the Bourne Shell), and is intended to conform to the IEEE P1003.2/ISO 69945.2 Shell and Utilities standard. ksh93u+ provides an enhanced 7programming environment in addition to the major command-entry 8features of the BSD shell "csh". With ksh93u+, medium-sized programming 9tasks can be performed at shell-level without a significant loss 10in performance. In addition, "sh" scripts can be run on ksh93u+ 11without modification. 12