#!/usr/bin/perl

# http://perlmonks.org/?node_id=1206910

use strict;
use warnings;
use File::Find;
$| = 1;

my $dir = 'A';

find({preprocess => \&before, wanted => \&when, postprocess => \&after}, $dir);

sub before
  {
  print "hi ";
  sort @_
  }

sub after { print "bye " }

sub when { print "file! $File::Find::name " }

##</code><code>##

file! A hi file! A/a1 file! A/a2 file! A/B hi file! A/B/b1 file! A/B/b2 bye file! A/C hi file! A/C/c1 file! A/C/c2 bye bye