postgresql - Create database from command line -

i´m trying create data base command line. centos , postgres 9.2

sudo -u postgres psql createdb test password user test: 

why asking me user?

change directory postgres :

su - postgres 

acces postgres shell

psql ( enter password postgressql) 

create user postgres

$ createuser testuser 

create database

$ createdb testdb 

provide privileges postgres user

$ alter user testuser encrypted password 'qwerty'; $grant privileges on database testdb testuser;