title: Exclude file from "git diff"
body: <p>I am trying to exclude a file (<code>db/irrelevant.php</code>) from a Git diff. I have tried putting a file in the <code>db</code> subdirectory called <code>.gitattributes</code> with the line <code>irrelevant.php -diff</code>
  and I have also tried creating a file called <code>.git/info/attributes</code> containing <code>db/irrelevant.php</code>. </p>
  
  <p>In all cases, the <code>db/irrelevant.php</code> file is included in the diff as a Git binary patch. What I want is for the changes to that file to be ignore by the diff command. What am I doing wrong?</p>