It's pretty limited (searching is sequential only, updates and deletes are painful, PAINFUL, PAINFUL) but you can always just open the file with fopen(),
explode() the line on your separator character to put the individual fields into an array or list(), and go from there. Note you'll have to prohibit the separator character from appearing in the data, otherwise your field count will get messed up.
To clarify: the pain of updating and deleting is how to make it work in the face of possible multiple users. There really isn't a good way, but using flock() to control access to the file will prevent outright corruption (at the expense of greatly reduced performance.)
If you really need a dbms, then moving hosts might be a better option.
