title: "cat /dev/random" versus "tail -f /dev/random"
body: <p>Statement </p>
  
  <pre><code>cat /dev/random
  </code></pre>
  
  <p>keeps producing output, as expected, but </p>
  
  <pre><code>tail -f /dev/random
  </code></pre>
  
  <p>hangs (at least on OSX and SUSE).
  Why the latter statement hangs?</p>