Create database from command line
Change the user to postgres :
su - postgres
Create User for Postgres (in the shell and NOT with psql)
$ createuser testuser
Create Database (same)
$ createdb testdb
Acces the postgres Shell
psql ( enter the password for postgressql)
Provide the privileges to the postgres user
$ alter user testuser with encrypted password 'qwerty';
$ grant all privileges on database testdb to testuser;
createdb
is a command line utility which you can run from bash and not from psql. To create a database from psql, use the create database statement like so:
create database [databasename];
Note: be sure to always end your SQL statements with ;
Try:
sudo -u postgres psql -c 'create database test;'