title: Get hostname mapped to IP Address from file similar to hosts file using BASH
body: <p>I have a file similar to hosts file where IP Address is mapped to hostname.
  Below is a snapshot of file </p>
  
  <pre><code>20.200.80.15   slave1
  20.200.80.16   slave2
  20.200.80.17   slave3
  20.200.80.18   slave4
  20.200.80.19   slave5
  20.200.80.20   master1
  </code></pre>
  
  <p>I would like to retrive Hostname from IP Address from the above file using <code>bash script</code> i.e. if I supply ipaddress as <code>20.200.80.18</code> then i should get output as <code>slave4</code></p>