Accounts are added automatically overnight based on the account information under /s/lab/lib. This is done by a modified version of make_passwd found under /etc on sp2-cw, and run by cron. Note that it doesn't (yet) remove accounts that no longer exist in the database. The account will then be created automatically on the other nodes by the SP2's "supper" utility, which updates collections of files every 10 minutes if they have been changed.