#!/usr/bin/perl
use strict;
use warnings;

my $data = 'pro my project con my customer date 2009-10-5 at 17:00 pri 2 msg Rack new server';
#pro = my project
#con = my customer
#date = 2009-10-5
#at = 17:00
#pri = 2
#msg = Rack new server

my @keywords = qw(pro con due date at pri msg);
# \b(pro|con|due|date|at|pri|msg)\s((?:(?!(pro|con|due|date|at|pri|msg)\b).)*)
my $regex = '\b(' . join('|', @keywords) . ')\s((?:(?!(' . join('|', @keywords) . ')\b).)*)';
while ($data =~ /$regex/ig) {
    print "$1 = $2\n";
}