use strict;

my $os_dispatch = {
    linux   => sub {print qq{Linux\n}},
    solaris => sub {print qq{Solaris\n}},
    aix     => sub {print qq{AIX\n}},
    freebsd => sub {print qq{FreeBSD\n}},
    darwin  => sub {print qq{MacOSX\n}},
    unknown => sub {print qq{Unknown\n}},
};

if (exists $os_dispatch->{$^O}) {
    $os_dispatch->{$^O}->();
}
else {
    $os_dispatch->{unknown}->();
}