(es) A unix shell written by Byron Rakitzis <byron@netapp.com> and Paul Haahr <haahr@adobe.com>, derived from rc. Es has real functions, closures, exceptions and lets you redefine most internal shell operations.

Version: 0.84.

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["Es - A Shell with Higher Order Functions", P. Haahr et al, Proc Winter 1993 Usenix Technical Conference].