title: Read STDOUT and STDERR from subprocess continiously
body: <p>I'm using <code>IO.popen</code> to start a subprocess, but I only get the result of everything that happened in the time it took for the subprocess to run (sometimes 5 minutes or whatever) when the subprocess exits. I really need to be able to see everything the subprocess writes to <code>stderr</code> and <code>stdout</code> as-and-when it happens.</p>
  
  <p>So far I could not find anything that works like this, but I'm sure it's possible.</p>