title: Using diff on only selected files in a directory/sub directory
body: <p>I'm trying to create a patch for a project of mine. <br> Essentially I have a directory with many files and subdirectories and my patch should only apply to a subset of files in various subdirectories.
  I can't use diff on the entire original vs modified directory because there are other files that will be affected by diff. Is there an automated way of using the diff command to create a patch only for a subset of files?</p>
  
  <p>The obvious way is to simply diff all individual files and then aggregate them in a single file with copy/paste, but is there an automated way of doing this? If not what is the preferred way of doing this?</p>