title: How to unzip files in a Heroku Buildpack
body: <p>I'm writing a custom <code>Heroku</code> <code>buildpack</code> (<a href="https://github.com/Fantom-Factory/heroku-buildpack-fantom" rel="nofollow noreferrer">heroku-buildpack-fantom</a>) for <a href="http://fantom-lang.org/" rel="nofollow noreferrer">Fantom</a>, and as part of the <code>compile</code> script I've downloaded a <code>.zip</code> file (from a language vendor), but how do I unzip it?</p>
  <p><code>unzip</code> is not a recognised command.</p>
  <p><code>gunzip</code> exists but <a href="http://www.unix.com/unix-dummies-questions-answers/75258-using-gunzip-decompress-zip-file.html" rel="nofollow noreferrer">I can't use it</a> to unzip .zip files.</p>
  <p>What am I missing?</p>