title: linux time command resulting real is less than user
body: <p>When I test a perl script under linux and use <code>time sh -c</code> to measure the time spent, I got a weird result:</p>
  
  <pre><code>real    14m11.903s
  user    34m39.319s
  sys     16m54.074s
  </code></pre>
  
  <p>which means the real time spent is even less than user time. And visually counting the time by myself, the script didn't spent as much as 34 minutes, and real time is closer to what I see. Has anyone have any clue about this? Thanks.</p>