Returns the next directory entry for a directory opened by opendir.
If used in list context, returns all the rest of the entries in the
directory. If there are no more entries, returns an undefined value in
scalar context or a null list in list context.
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;