Somewhat off-topic, but hard to find better portability people.

[Peter Seebach]

Hi!  Gary Vaughn pointed me at gnulib for portability experts.

I've been working on some portable shell scripting material.  I'm trying to
track down the details of a couple of "some systems can't..." comments from
the Autoconf documentation, because I haven't been able to find any such
systems.

I am looking for systems on which the following *do not* work:

unset
"$@" (expanding to null, not an empty string, when no positional parameters)
shift N
getopts
set -- args

I had been using Solaris's shell as the "oldest shell I can still find", but
all of these work in it.

(As is so often the case, "portable" is not exactly a boolean; what I want to
be able to do is tell people not just that there exists a machine where
one of these doesn't work, but what it might be, so they can make informed
decisions about it.)

-s