#!/usr/bin/perl

use strict;
use warnings;

# user input:
my $regexp='^http://www.example.com/(\d+)/([a-z]+.zip)$';
my $template='https://secure.foobar.lan/fetch?file=$2&id=$1&missingValue=$3';

# data
my $url='http://www.example.com/12345/foo.zip';


# actual program
my @array=($url=~/$regexp/);
my $result=$template;
do {
	no warnings 'uninitialized';
	$result=~s/\$(\d+)/$array[$1]/ge;
};

print "'$url' rewritten to '$result'\n";