#!/usr/bin/perl
use strict;
use warnings;
use diagnostics;
my $datum = '21.01.2010';
my %konfig = (
	default_vertragsbeg	=> sprintf '01.%02u.%04u',(split /\./,$datum)[1..2],
	foo => 'test',
	bar => 'test2',
);
foreach (keys %konfig) { print "$_ => $konfig{$_}\n" }