>From perlvar...

  HANDLE->input_line_number(EXPR)
  $INPUT_LINE_NUMBER
  $NR
  $.      Current line number for the last filehandle accessed.
          ...
          You can adjust the counter by assigning to $., but this will
          not actually move the seek pointer.  Localizing $. will not
          localize the filehandle's line count.  Instead, it will local-
          ize perl's notion of which filehandle $. is currently aliased
          to.

...something to keep in mind.

- parv