$f = fopen($file, 'r');
$line = 1;

$contents = null;
while(!feof($f))
{
   $char = fgetc($f)
   if($char == "\n" || $char == "\r") $line++;
   if($line >= $START)
   {
      while($line <= $END)
      {
         $contents .= fgets($f)
         $line++;
      }
      return $contents
   }