initlocation $environment_variable
Creating a database storage area consists of creating the directories in which the database data will live. There are 2 types of arguments for initlocation. First, you can specify an explicit absolute path to the top directory of the storage area. Second, you can specify an environment variable (e.g. $PGDATA2). This environment variable should be known to the backend for later use in create database. In either case Postgres will add /base/ to the specified path to create the storage area.