#!/usr/bin/perl

use strict;
use warnings;

use XML::Twig;

my $t= XML::Twig->new( twig_roots => { 'package/metadata/x-metadata/meta[@name="dtb:totalTime"]'
                                          # $_ is the current element
                                       => sub { $_->set_att( content => $_->att( 'content') +1);  $_->print; } },
                       twig_print_outside_roots => 1,
                     )
                ->parsefile( 'package.xml');