title: Submitting parallel unix jobs with hierarchy
body: <p>I need to run 3 jobs with the following conditions -</p>
  
  <ol>
  <li><p><code>job2</code> depends on <code>job1</code>.</p></li>
  <li><p><code>job3</code> can run independently of <code>job1</code> or <code>job2</code>.</p></li>
  <li><p><code>job4</code> should start only when <code>job2</code> and <code>job3</code> both are complete.</p></li>
  </ol>
  
  <p>I can run <code>(job1; job2)</code> to ensure job2 runs after job1. What's the best way to start all the jobs at once to make maximum use of parallelization?</p>