protecting pages with a login system

Hi, I am wanting to protect some pages by requiring a user to log in to access them. I'd prefer this be as simple as possible, and without requiring a database. So for example when a user goes to www.domain.com/example.php they'll get a page prompting for their log in credentials, and only after providing them will the page display. I'd prefer to avoid basic authentication dialog boxes if possible. Suggestions appreciated. Thanks. Dave.