%hash = (
    "j" = "jack",
    "q" = "queen",
    "k" = "king",
    "a" = "ace"
);

one( \%hash);

sub one {
    my ($hash) = @_;
    if ( <STDIN> eq "hello\n" ) {
        two( \%$hash); # should this be two( $hash ); ?
    }
}

sub two {
    my ($hash) = @_;
    foreach ( keys %$hash ) {
        print "$_\n";
    }
}