To create a database, you must be a superuser or have the special CREATEDB privilege. Normally, the creator becomes the owner of the new database. Non-superusers with CREATEDB privilege can only create databases owned by them.
The new database will be created by cloning the standard system database template1.
The name of the database to be created.
CREATE DATABASE cannot be executed inside a transaction block.
Errors along the line of “could not initialize database directory” are most likely related to insufficient permissions on the data directory, a full disk, or other file system problems.