not to say it's impossible, but it's certainly not something you can do easily.
Quota files are owned by root, your web server is (hopefully) not running as root.
When creating quotas for users, make a record in a db, read the record for user's quota.
As far as changing the password is concerned, again, only root can do so and passwd doesn't take arguments other than user_name.
Are these shell users you're trying to write an app for? If they're ftp / pop users look into virtualizing the accounts and writing a small panel for user-control in db / text file.
Probably not the answer you were looking for :rolleyes:
-m.
