If you're planning to filetest the return values out of a
            "readdir", you'd better prepend the directory in question.
            Otherwise, because we didn't "chdir" there, it would have been
            testing the wrong file.

                opendir(DIR, $some_dir) || die "can't opendir $some_dir: $!";
                @dots = grep { /^\./ && -f "$some_dir/$_" } readdir(DIR);
                closedir DIR;