use strict;

my $dir = "/";
my $file;

sub openNewDir {
    $dir = shift;
    opendir (DIR, $dir);
    while ($file = readdir (DIR)) {
        if (-d $file) { openNewDir($dir.$file."\\"); } 
        else {
            # Do something with the file
        }
    }
    close (DIR);
}

openNewDir ($dir);