Hi,

From how I understood your question, you want to get the total for each columns... So, I replaced this code

for my $to (sort keys %from_to_bytes){
        printf "%10s", "$from_to_bytes{$to}";
}
[download]

with this one.

my %total_col;
for my $i (keys %from_to_bytes) {
    for my $j (keys %{ $from_to_bytes{$i} }) {
        $total_col{$j} += $from_to_bytes{$i}->{$j};
    }
}

print " " x 11;
for my $i (sort keys %total_col) {
    printf " %10s", "$total_col{$i}";
}

print "\n";
[download]

Although as you can see there is some more work needed in the formatting. Hope this helps.