title: What does the FD column of pipes listed by lsof mean?
body: <p>I'm using the following command to get a list of pipes:</p>
  
  <pre><code>lsof | grep PIPE 
  </code></pre>
  
  <p>I want to know what the values of the FD column mean (the 5th one <a href="http://i.imgur.com/KHczptf.png" rel="noreferrer">http://i.imgur.com/KHczptf.png</a>). I think that <code>r</code> and <code>w</code> mean <strong>read</strong> and <strong>write</strong>, respectively, but what does the number which follows each of these chars means?</p>
  
  <hr>
  
  <p>I know that FD means File Descriptor, what I want to figure out is what means the values shown in the column, like the 3r, 16w, 20r, etc.</p>