Java™ Application Development on Linux - Dator

14.9 Setting Up PostgreSQL for BudgetPro32314.9.2 Creating a postgres UserMore than likely, installing a PostgreSQL package will create a new Linux usercalled postgres on your system. This is not a login account; it will be used bythe database server process daemon 11 (called “postmaster,” lest you think thatit might be an e-mail server or something). Furthermore, only the postgresuser is able to create additional database users or any databases.Obviously, we won’t want it to be like this forever. It has the same problemas the root user on the OS itself: There’s one magic user with all thepower. You’ll need to create additional users and you’ll want to limit what theycan do. How to do it?First off, you can’t log in as postgres, so you will have to become rootand then su to the postgres user:[mschwarz@cassidy mschwarz]$ su -Password:[root@cassidy root]# su - postgres-bash-2.05b$Note that postgres didn’t have any profile or rc script to set up promptsor anything.All PostgreSQL databases have owning users, in much the same way thatall Linux files have owning users. But PostgreSQL users are not necessarily thesame as Linux users. 12 The only PostgreSQL user that exists “out of the box”is postgres. You must use the createuser command-line utility (or theequivalent SQL) to create a user. Here’s an example:11. Historically, daemon processes on UNIX systems used to be run as root. But a programerror in a daemon would allow a malicious user to execute code as the owner of the process. Ifthat owner is root, one programming mistake in a server process could give an attacker totalcontrol of the system. Beware of any daemon process that runs as root. Nowadays, these runas either a totally nonpriviledged user such as nobody, or, if they really need to write files orsome such thing, as a catch-all user like daemon. The database is an important process and itneeds its own security, so it runs as its own user, postgres.12. For most PostgreSQL command-line utilities, if no PostgreSQL username is specified, thecurrent Linux username will be used. This is often a convenient choice, but you might havecompelling reasons not to do this.