title: how to continuously display a file of its last several lines of contents
body: <p>I am trying to find a Unix command (combination, maybe) on how to continuously display a file of its last several lines of contents. But during this displaying, I want some of the top lines are always displayed on the screen top when the rolling contents reach the screen top.</p>
  <p>Is that possible?</p>
  <ol>
  <li>Suppose I have file, &quot;job.sta&quot;, the first 2 lines are:
  <pre><code>job name, John's job on 2013-Jan-30,...
  Tab1, Tab2, Tab3
  0, 1, 2,
  1, 90, 89
  2, 89, 23
  ...
  </code></pre>
  </li>
  <li>This file is on its running, its contents are growing, and I don't know what line it's going to end.</li>
  <li>So I want to display (always) the first 2 lines when using tail command, when the updating contents reaches a Unix shell screen top. I am using PuTTY at the moment.</li>
  </ol>
  <p>Reference:
  <a href="http://www.unix.com/unix-dummies-questions-answers/172000-head-tail-how-display-middle-lines.html" rel="noreferrer">http://www.unix.com/unix-dummies-questions-answers/172000-head-tail-how-display-middle-lines.html</a></p>