in reply to using keys on hash of hash

How about using an approach that makes it easier to understand your logic.
use Data::Dumper qw(Dumper); my %hash = ( 'h1' => { 'k1' => 'vh1k1', 'k2' => 'vh1k2', }, 'h2' => { 'k1' => 'vh2k1', 'k2' => 'vh2k2', } ); my $key = 'h1'; my $results = find_results_for( $key ); if ($results) { print "Results for $key: " . Dumper( $results ) . "\n"; } else { print "Cannot find anything for $key\n"; } sub find_results_for { my $search_key = shift; return if not exists $hash{$search_key}; return $hash{$search_key}; }

Avoid using nested loops without a very good reason. They can be hard to follow, better to put then in a subroutine that can explain what you looking for.