the extension is grotesquely non-portable.
As requested by Denny Gentry in pr-3914. He supplied some code, but I
used all my own code in the change, and wrote documentation for the
man page.
This is creeping featurism at its worst. I added it only because I
can't see a good reason for refusing. However, I'm disgusted with
myself for doing it anyway.
are distinct (See POSIX.2 glossary).
A utility is a executable, script or shell builtin; while a command
can be any of those things plus lists, pipelines, compound commands
(if, for, while) and shell function definitions.
