title: find the string and print out the line before and after- unix scripting
body: <p>right now i have this code</p>
  
  <pre><code> FNR==NR  { id[$0]; next } 
   $0 in id { f=1 }         
   f                          
   NF==0    { f=0 }   
  </code></pre>
  
  <p>and i want to print out the line before the string found as well.</p>
  
  <p>How would i modify this code to do so??</p>