title: How to wait for a child process to finish in Node.js
body: <p>I'm running a Python script through a child process in Node.js, like this:</p>
  <pre><code>require('child_process').exec('python celulas.py', function (error, stdout, stderr) {
      child.stdout.pipe(process.stdout);
  });
  </code></pre>
  <p>but Node doesn't wait for it to finish. How can I wait for the process to finish?</p>
  <p>Is it possible to do this by running the child process in a module I call from the main script?</p>