My question too

On Odoo 9.0 (and I guess also 8.0), if test_database does not exist, the exact command you wrote will create it automatically through the -d flag...

stackoverflow.com/questions/876522/creating-a-copy-of-a-database-in-postgres (can't post links so removed the http part)

From there duplicating db from command line:

createdb -O ownername -T originaldb newdb

Haven't tested this one but would assume that it works because it has been voted as a good answer.

# thanks to https://pythonhosted.org/OERPLib/

I have been able to create a database using oerplib from https://pythonhosted.org/OERPLib/, one of the two client libraries I have found "out there", the other being openerplib from https://pypi.python.org/pypi/openerp-client-lib.

Using oerplib:

# pip install oerplib

# python
>>> import oerplib
>>> jconn = oerplib.rpc.ConnectorJSONRPC('localhost', port=8069)
>>> jconn.proxy.web.database.get_list()
>>> jconn.proxy.web.database.create(fields=[{'name': 'super_admin_pwd', 'value': 'master-secret'}, {'name': 'db_name', 'value': 'my-new-database'}, {'name': 'create_admin_pwd', 'value': 'secret'}, {'name': 'create_confirm_pwd', 'value': 'secret'}, {'name': 'db_lang', 'value': 'en_US'}])

There are more concise mechanisms also, without all the 'name', 'value', etc.
This mechanism as written has indeed create a database for me.

God speed on your database creation automation journey,