#!/usr/bin/perl
use warnings;
use strict;

my %hash1 = (key1 => [qw(val1 val2)],
             key2 => ['val3'],
             );
my %hash2 = (val1 => [qw(val5 val6 val7)],
             val2 => [qw(val8 val9)],
             val3 => ['val3'],
            );
my %result = (map { $_ => [ map @{ $hash2{$_} } ,
                                @{ $hash1{$_} }
                          ]
                  } keys %hash1);

while (my ($k, $v) = each %result) {
    print $k, " @$v\n";
}
[download]

This is so great.

But the values in my hash1 are not arrays, they are strings with each key for hash2 separated by comma ",". How should I turn the strings in to array so that I could adapt to the code?

Thanks again, great help!

Ah, ok, that was originally not clear from the question. You can use split to get the list from the string:

#!/usr/bin/perl
use warnings;
use strict;

my %hash1 = (key1 => 'val1,val2',
             key2 => 'val3',
             );
my %hash2 = (val1 => 'val5,val6,val7',
             val2 => 'val8,val9',
             val3 => 'val3',
            );
my %result = map { $_ => join ',', map split(/,/, $hash2{$_}),
                                       split /,/, $hash1{$_}
                 } keys %hash1;

while (my ($k, $v) = each %result) {
    print "$k: $v\n";
}
[download]

لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ