use strict;
use Cwd;

my $cwd = Cwd::getcwd();
my $directory = shift(@ARGV) || $cwd;
$directory = $cwd . '/' . $directory unless $directory =~ /^\//;
my @queue = ($directory);

while (@queue) {
    my $node = shift(@queue);

    if (-d $node) {
        opendir(DIR, $node);
        push(@queue, map { $node . '/' . $_ } 
                     grep { $_ ne '.' and $_ ne '..' and $_  !~ /^_/ }
                     readdir(DIR));
        closedir(DIR);
    }
    else {
        do_your_stuff($node);
    }
}