[Mailman-Users] Using cronjob to remove and add members to a mailing list

I want to be able to run a cronjob on my server that uses a php script to add new users and/or remove users from a mailing list. Not having any luck finding any simple examples. My thought is that the php script would get email addresses from a database (which I can do) and then feed them to a mailman command line to either add or remove a user.

The cronjob is entered via Cpanel. Have several cronjobs that modify databases but have never tried something that would actually execute a unix command.

Thanks, Pineyscripter