#!/usr/bin/perl use warnings; use strict; print map unpack( 'x3 a*', $_ ), sort map pack( 'n a a*', /(\d+)([A-Z])/, $_ ), grep /\S/, ; __DATA__ K-2-D-10A K-2-D-10C K-2-D-10D K-2-D-10E K-2-D-10F K-2-D-10G K-2-D-11A K-2-D-11B K-2-D-12I K-2-D-12J etc. etc.