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

my $mac = '28:8a:1c:59:cc:85';

(my $finalmac = $mac) =~ s/(\w+):(\w+)(:?)/$1$2./g;
$finalmac =~ s/.$//; #ditch "." at end

(my $atmac = $mac) =~ tr/:/ /;

print "mac        = $mac\n";
print "atmac      = $atmac\n";
print "final mac  = $finalmac\n";

__END__
mac        = 28:8a:1c:59:cc:85
atmac      = 28 8a 1c 59 cc 85
final mac  = 288a.1c59.cc85