title: Fetch particular column value from rows with specified condition using shell script
body: <p>I have a sample output from a command</p>
  
  <pre><code>+--------------------------------------+------------------+---------------------+-------------------------------------+ 
  | id                                   | fixed_ip_address | floating_ip_address | port_id                             |
  +--------------------------------------+------------------+---------------------+-------------------------------------+
  | 04584e8a-c210-430b-8028-79dbf741797c |                  | 99.99.99.91        |                                      |
  | 12d2257c-c02b-4295-b910-2069f583bee5 | 20.0.0.92        | 99.99.99.92        | 37ebfa4c-c0f9-459a-a63b-fb2e84ab7f92 |
  | 98c5a929-e125-411d-8a18-89877d3c932b |                  | 99.99.99.93        |                                      |
  | f55e54fb-e50a-4800-9a6e-1d75004a2541 | 20.0.0.94        | 99.99.99.94        | fe996e76-ffdb-4687-91a0-9b4df2631b4e |
  +--------------------------------------+------------------+---------------------+-------------------------------------+
  </code></pre>
  
  <p>Now I want to fetch all the <em>"floating _ip_address"</em> for which <em>"port_id"</em> &amp; <em>"fixed_ip_address"</em> fields are <strong>blank/empty</strong> (In above sample 99.99.99.91 &amp; 99.99.99.93)</p>
  
  <p>How can I do it with shell scripting?</p>