Using Grandfather's elegant solution, I reversed the condition and built a simple until loop out of that.

#!/usr/bin/perl -l

use strict;
use warnings;

my $name = '';
until ( $name eq 'q' ) {
    print "Enter the wwn: ";
    chomp( $name = lc <STDIN> );
    print join( ':', unpack( "(a2)*", $name ) );
    next;
}
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