The Korn shell has a number of options that specify your environment and control execution. There are options that cause background jobs to be run at a lower priority, prevent files from being overwritten with redirection operators, disable filename expansion, specify the vi-style in-line command editor, and more.
|set –a, set –o allexport||automatically export variables when defined|
|set –o bgnice||execute all background jobs at a lower priority|
|set –o emacs, set –o gmacs||use emacs/gmacs in-line editor|
|set –o ignoreeof||do not exit on end ...|