#!/usr/bin/perl -w
use strict;
use Data::Dumper;
my $mountpoint = '/media/sdb2';

my %filesystem;

$filesystem{$mountpoint} = traverse($mountpoint);

sub traverse{
        my %hash;
        my ($folder) = $_[0];
        opendir DIR,$folder;
        my @content = grep {!/^\.{1,2}$/} readdir DIR;
        closedir DIR;

        foreach my $entry(sort @content){
                if(-f $folder."/".$entry){
                        $hash{lc $entry} = $entry;
                }elsif( -d $folder."/". $entry){
                        $hash{$entry}= traverse($folder."/".$entry);
                }else{
                        print $folder."/".$entry." ignoring\n";
                };  
        };  
        return %hash;
};

print Dumper %filesystem;

##</code><code>##

$hash{aaa}{bbb}{ccc}="ccC";
if(exists $hash{lc aAa}{lc bBB}{lc CCC}){
  print "exists: $hash{lc aAa}{lc bBB}{lc CCC}\n";
}else{
  print "not exists\n";
};