title: Filenames are lost when I find multiple pdf files, xarg pdftotext, and grep pattern
body: <p>I want to make a shell script for searching pattern in pdf files (to make them kind of corpus for myself!!)</p>
  
  <p>I stole the following snippet from here</p>
  
  <p><a href="https://stackoverflow.com/questions/4643438/how-to-search-contents-of-multiple-pdf-files">How to search contents of multiple pdf files?</a></p>
  
  <pre><code>find /path/to/folder -name '*.pdf' | xargs -P 6 -I % pdftotext % - | grep -C1 --color "pattern"
  </code></pre>
  
  <p>and the output looks like this</p>
  
  <pre><code>--
  --
  small deviation of γ from the average value  0.33 triggers
  a qualitative difference in the evolution pattern, even if the
  </code></pre>
  
  <p>Can I make this command to print filename?</p>
  
  <p>It doesn't have to be a "one-liner".</p>
  
  <p>Thank you.</p>