# am Anfang des Programms:
$SIG{__WARN__} = \&warningToFile;

sub warningToFile{
  my $f;
  if(open($f, ">>",$error_log)){
      my($sec, $min, $hour, $mday, $mon, $year) = localtime(time);
      print $f (sprintf("%2d.%02d.%04d %02d:%02d:%02d   ", $mday, ($mon + 1), ($year + 1900), $hour, $min, $sec))."@_\n";
      close($f);
  }
  else{
    warn "Could not open $error_log!";
  }
}