title: Windows 'findstr' command: Exclude results containing particular string
body: <p>To the command <code>findstr str1 *.*</code> I want to add something that will exclude the results which contain the string <code>str2</code>. </p>
  
  <p>In Linux the way of doing it is to add <code>| grep -v str2</code> (to <code>grep str1 *</code> of course). Is there an equivalent flag to <code>-v</code>  in Windows?</p>