To create a new database, in this example named mydb, you use the following command:

$ createdb mydb

This should produce as response:

CREATE DATABASE

If so, this step was successful and you can skip over the remainder of this section.

If you see a message similar to createdb: command not found then PostgreSQL was not installed properly. Either it was not installed at all or the search path was not set  correctly. Try calling the command with an absolute path instead:

$ /usr/local/pgsql/bin/createdb mydb

The path at your site might be different. Contact your site administrator or check back in the installation instructions to correct the situation.

Another response could be this: psql: could not connect to server: Connection refused Is the server running locally and accepting connections on Unix domain socket "/tmp/.s.PGSQL.5432"?
createdb: database creation failed

This means that the server was not started, or it was not started where createdb expected it.

Again, check the installation instructions or consult the administrator.

If you do not have the privileges required to create a database, you will see the following:
ERROR: CREATE DATABASE: permission denied createdb: database creation failed Not every user has authorization to create new databases. If PostgreSQL refuses to create databases for
you then the site administrator needs to grant you permission to create databases. Consult your site administrator if this occurs. If you installed PostgreSQL yourself then you should log in for the purposes of this article under the user account that you started the server as. 1

You can also create databases with other names. PostgreSQL allows you to create any number of databases at a given site. Database names must have an alphabetic first character and are limited to 31 characters in length. A convenient choice is to create a database with the same name as your current user name. Many tools assume that database name as the default, so it can save you some typing. To create that database, simply type:

$ createdb

If you don’t want to use your database anymore you can remove it. For example, if you are the owner (creator) of the database mydb, you can destroy it using the following command:

$ dropdb mydb

(For this command, the database name does not default to the user account name. You always need tospecify it.) This action physically removes all files associated with the database and cannot be undone, sothis should only be done with a great deal of forethought.