title: extract average time from ping -c
body: <p>I want to extract from the command <code>ping -c 4 www.stackoverflow.com | tail -1| awk '{print $4}'
  </code> the average time.</p>
  
  <pre><code>107.921/108.929/110.394/0.905 ms
  </code></pre>
  
  <p>Output should be: <code>108.929</code></p>