use warnings; use strict; use Data::Dump::Streamer; my %hash1 = ( foo => 'bar', baz => { quux => 'qwe', rty => 'uiop', }, perl => ['monks', 'monastery', 'robes'], ); my %hash2 = ( wizardry => 'hocus-pocus', foo => 'f00', baz => { grail => 'arthur', }, perl => ['yayy', 'yippee'], hash3 => {key1 => 'value1', key2 => 'value2', }, ); merge (\%hash2, \%hash1); Dump (\%hash1); sub merge { my ($source, $target) = @_; for (keys %$source) { if ('ARRAY' eq ref $target->{$_}) { push @{$target->{$_}}, @{$source->{$_}}; } elsif ('HASH' eq ref $target->{$_}) { merge ($source->{$_}, $target->{$_}); } else { $target->{$_} = $source->{$_}; } } } #### $HASH1 = { baz => { grail => 'arthur', quux => 'qwe', rty => 'uiop' }, foo => 'f00', hash3 => { key1 => 'value1', key2 => 'value2' }, perl => [ 'monks', 'monastery', 'robes', 'yayy', 'yippee' ], wizardry => 'hocus-pocus' };