#!/usr/bin/perl

use strict;
use warnings;

use Data::Dumper;

$Data::Dumper::Sortkeys = 1;

my %hash = (
	-a => 1,
	-b => 2,
	-c => 3,
);

print Dumper( \%hash ), "\n\n";

my %add_hash = (
	-d => 4,
	-e => 5,
	-f => 6,
);

my @keys_add_hash = keys %add_hash;

@hash{ @keys_add_hash } = @add_hash{ @keys_add_hash };

print Dumper( \%hash );