Re: [PATCH] Make sure to use Araxis' "compare" and not e.g. ImageMagick's

From: Junio C Hamano <gitster@pobox.com>
Date: Jul 23, 2012, 21:24 UTC
Message-ID: <7vipdejhmh.fsf@alter.siamese.dyndns.org>
In-Reply-To: <CAHGBnuOz94YR9wx_goL5YaWzPt5Z9c3gBB9CtyfcE40F5amrXw@mail.gmail.com>

Sebastian Schuberth <sschuberth@gmail.com> writes:

> We have no such assurance. That's why you correctly call it a
> heuristics after all

ImageMagick "compare" takes "--version" and says something like this to its standard output:

    $ compare --version
    Version: ImageMagick 6.6.0-4 2012-05-02 Q16
    http://www.imagemagick.org
    Copyright: Copyright (C) 1999-2010 ImageMagick Studio LLC

Does Araxis compare take "--version" and behave in a way that is cheaply controllable? If it opens a GUI window and pops up a dialog that says "Option not understood", then it is not "controllable", but if it quickly dies with "No such option" sent to the standard error output, or sending its version string to the standard output, then we could use something like:

	case "$(compare --version 2>/dev/null)" in
        "Araxis compare version"*)
        	echo compare ;;
	*)
        	echo "$1" ;;
	esac

instead, and that would be more robust than the path based heuristics.