But *nix has no such feature, nor the associated gotcha.

On Aug 15, 2016 11:01 AM, "Eli Zaretskii" <eliz@gnu.org> wrote:

> > From: npostavs@users.sourceforge.net
> > Date: Sun, 14 Aug 2016 23:13:43 -0400
> > Cc: 19350@debbugs.gnu.org
> >
> > Hmm, maybe we could fix this by making Emacs refuse to apply environment
> > variables with names ending in carets?
>
> I'm very much against disallowing perfectly valid (if rare) use cases
> just because someone malicious can take advantage of that.
>
> From my POV, as long as Emacs itself doesn't produce such shell
> commands and/or environment variables for any of its features,
> avoiding this becomes user's responsibility, just like when working at
> the shell prompt.  Of course, if we can find a reliable solution to
> the problem that doesn't take away features, that'd be better, but
> failing that, I'm okay with leaving this alone, perhaps documenting
> somewhere that using % in shell commands when there are environment
> variables ending in ^ could produce surprising results.
>
> Thanks.
>