title: one liner to extract ip address with last octet replaced with 0
body: <p>I have  Beaglebone Black based custom board,<br>
  I want to extract ip address of an interface eth0 and replace fourth octet with 0.<br>
  I am using below one liner for extracting ip,</p>
  
  <pre><code>ip addr show eth0 | awk  '$1=="inet"{print $2}'
  output : 192.168.2.158/24
  
  Expected output : 192.168.2.0/24
  </code></pre>
  
  <p>however I am not able to make fourth octet 0, I thought of using function <code>gsub</code> however not able to get right combination. :(</p>
  
  <p>I don't want more pipes in the command.</p>
  
  <p>Any suggestion/pointers ?</p>
  
  <p>Any other suggestion?</p>