title: Grep search strings with line breaks
body: <p>How to use grep to output occurrences of the string 'export to excel' in the input files given below? Specifically, how to handle the line breaks that happen in between the search strings? Is there a switch in grep that can do this or some other command probably?</p>
  
  <p>Input files:</p>
  
  <p>File a.txt:</p>
  
  <blockquote>
    <p>blah blah ... export to<br>
    excel ...<br>
    blah blah..</p>
  </blockquote>
  
  <p>File b.txt:</p>
  
  <blockquote>
    <p>blah blah ... export to excel ...<br>
    blah blah..</p>
  </blockquote>