#!/usr/bin/perl
use strict;
use warnings;
use File::Find;
use File::stat;

print format_size( dir_usage('/home') )."\n";

#dir usage
sub dir_usage
{
  my $summ=0;
  find(sub
  {
    my $file=$File::Find::name;
    return if($file eq '.' || $file eq '..');
    $summ+=stat($file)->size();
  },@_);
  return $summ;
}

# format size
sub format_size
{
  my $size=shift || 0;
  my @formats=qw(Byte Kb Mb Gb Tb Pb);
  while($size>=1024 && @formats>1)
  {
    shift(@formats);
    $size/=1024;
  }
  return sprintf('%.02f %s',$size,$formats[0]);
}