新しいユーザ作る
postgresql 8.2で。
sudo -u postgres createuser ar_user -P Enter password for new role: Enter it again: Shall the new role be a superuser? (y/n) n Shall the new role be allowed to create databases? (y/n) n Shall the new role be allowed to create more new roles? (y/n) n CREATE ROLE
消すとき
sudo -u postgres dropuser ar_user