$~ = "HEADER"; write;

$~ = "INHALT";
foreach (0..$#bestellung) {
($text, $nr, $preis, $menge) = split(/\|/, $bestellung[$_]);
$summe = sprintf("%.2f", $menge*$preis);
... irgendwas ...
write; 
}

$~ = "FOOTER"; write;