Such tools are for example scons is a make alternative that rethinks make&#39;s &quot;older timestamp =&gt; rebuild&quot;<br><br>From <a href="http://www.scons.org/architecture/index.html">www.scons.org/architecture/index.html</a><br>
<tt class="APPLICATION"><br></tt><blockquote style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;" class="gmail_quote"><i><tt class="APPLICATION">(S)Cons</tt> decides if a file was out-of-date by using MD5 checksums of
        the contents of files, not timestamps.

      </i><br></blockquote><br><br>SCons also comes to mind because you are using make for R not (traditional) programming<br><br><br><blockquote style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;" class="gmail_quote">
<i>Most of the build tools just mentioned
    were written by programmers and for
    programmers. The fact that most programmer-friendly
    utilities do a poor job of fulfilling the needs
    of non-programmers prompted Greg Wilson to
    organize the Software Carpentry competition in January 2000.
    Software Carpentry was an
    open design contest with the express goal of producing a set of
    next-generation utilities, including a build tool, that would be
    accessible
    not only to
    programmers
    but also to computer </i><i class="EMPHASIS">users</i><i>
    such as physical scientists.

  </i></blockquote><div><br><br>[Disclaimer: Ive not tried scons myself] <br></div>