sub print_rec {

##</code><code>##

opendir DIR, shift;

##</code><code>##

if(!/\.|\.\./ && -d $_)

##</code><code>##

return print_rec($_);

##</code><code>##

elsif (!-d) { ... }

##</code><code>##

#!/usr/bin/env perl -l

use strict;
use warnings;
use autodie;

use constant INDENT => ' ' x 4;

my $starting_dir = '.';

print_dir_listing($starting_dir, '');

sub print_dir_listing {
    my ($path, $indent) = @_;

    opendir my $dh, $path;

    for (readdir $dh) {
        next if /^(?:\.|\.\.)$/;

        if (-d "$path/$_") {
            print "${indent}DIR: $_";
            print_dir_listing("$path/$_", $indent . INDENT);
        }
        else {
            print "$indent$_";
        }
    }
}

##</code><code>##

...
DIR: mastering_perltk_demo_code
    mastperltk_examples.MANIFEST
    mastperltk_examples.tar.gz
    DIR: mptk-code14
        DIR: ch01
            hello-world
        DIR: ch02
            play-with-pack1
            play-with-pack2
        DIR: ch03
            banner
            fontviewer
        DIR: ch04
...