I didn't see cpan mentioned either, however since Ubuntu uses bash 'out of the box' the up arrow key works fine for command recall. While I agree that a broken shell is a possability I'd expect not the OP to have asked for help accessing previous commands rather than 'previous Perl' as explicitly stated. The modules I mentioned don't ship with with perl/ubuntu as default. Weither it's cpan related or as LanX suggests perl debugger, the advice I've given is accurate. However, as you quite accuratly state, without knowing exactly what the OP is really asking for, it could be several things.