*nix command of the day:
diff -Naur old new > new.patch
Where “old” and “new” are files or directories to patch.
Example (a Drupal patch for IDs duplication):
$ patch -p0<fapi-5.x-dupe-id_111719-151.patch
patching file includes/form.inc
$
Creating patch for Drupal:
diff -up original.php new.php > filename.patch
another example:
diff -up path/to/file/example.module path/to/file/exampleNew.module > mypatchname.patch
See also: