title: linux|awk|shell script modification of line with same name in many blocks
body: <pre><code>My input file has blocks like below. 
  
  [abc]  
  para1=123  
  para2=456  
  para3=111  
  
  [pqr]  
  para1=333    
  para2=765    
  para3=1345    
  
  [xyz]    
  para1=888    
  para2=236    
  para3=964    
  </code></pre>
  
  <p>now how do i modify the value of para2 inside the block pqr alone without the value being changed in other blocks or the first block alone.Please help me achieve this with awk or perl or sed commands.Thanks in advance</p>