Before you can use PostgreSQL you need to install it, of course. It is possible that PostgreSQL is already installed at your site, either because it was included in your operating system distribution or because the system administrator already installed it. If that is the case, you should obtain information from the operating system documentation or your system administrator about how to access PostgreSQL .
If you are not sure whether PostgreSQL is already available or whether you can use it for your experimentation then you can install it yourself. Doing so is not hard and it can be a good exercise. PostgreSQL can be installed by any unprivileged user; no superuser ( root ) access is required.
If you are installing PostgreSQL yourself, then refer to Chapter 16 for instructions on installation, and return to this guide when the installation is complete. Be sure to follow closely the section about setting up the appropriate environment variables.
If your site administrator has not set things up in the default
way, you might have some more work to do. For example, if the
database server machine is a remote machine, you will need to set
environment variable to the name of the
database server machine. The environment variable
might also have to be set. The bottom line is
this: if you try to start an application program and it complains
that it cannot connect to the database, you should consult your
site administrator or, if that is you, the documentation to make
sure that your environment is properly set up. If you did not
understand the preceding paragraph then read the next section.