sprintf is your friend:

my ( $sec, $min, $hour, $mday, $mon, $year, $wday, $ydat, $isdst ) = l
+ocaltime();
my $jahr = $year + 1900;
my $monat = sprintf "%02d", $mon + 1;
my $tag = sprintf "%02d", $mday;
$hour = sprintf "%02d", $hour;
$min = sprintf "%02d", $min;
$sec = sprintf "%02d", $sec;
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