This is Debian/GNU Linux's prepackaged version of es.  Es is an
extensible shell.  The language was derived from the Plan 9 shell, rc,
and was influenced by functional programming languages, such as
Scheme, and the Tcl embeddable programming language.

es was previously maintained by Joost Witteveen.  The current package
was put together by me, James Troup <jjtroup@comp.brad.ac.uk>, from
the source, which I obtained from
ftp.cs.uchicago.edu:/pub/users/csdayton/es-0.9-beta1.tar.gz.  The
changes were small:

o adding support for the Debian package maintenance scheme, by adding
  various debian/* files.
o stdenv.h: unconditionalize the #inclusion of <sys/types.h> as it's
  needed for the prototype of gid_t.
o stdenv.h: don't try to #include <stdlib.h> as input.c tries to
  redefine getenv().

es was written by Paul Haahr and Byron Rakitzis and is in the public
domain.

es is under the following copyright:

     We hold no copyrights or patents on the source code, and do not
     place any restrictions on its distribution.  We would appreciate
     it if any distributions do credit the authors.