If your site administrator has not set things up in the default way, you might have some more work to do. Be sure to follow closely the section about setting up the appropriate environment variables. If you are installing PostgreSQL yourself, then refer to Chapter 17 for instructions on installation, and return to this guide when the installation is complete. PostgreSQL can be installed by any unprivileged user no superuser ( root) access is required. Doing so is not hard and it can be a good exercise. 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. If that is the case, you should obtain information from the operating system documentation or your system administrator about how to access PostgreSQL. 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. Before you can use PostgreSQL you need to install it, of course.

Postgresql install centos 7