[postgresql] PostgreSQL: How to change PostgreSQL user password?

TLDR:

On many systems, a user's account often contains a period, or some sort of punction (user: john.smith, horise.johnson). IN these cases a modification will have to be made to the accepted answer above. The change requires the username to be double-quoted.

Example:

ALTER USER "username.lastname" WITH PASSWORD 'password'; 

Rational:

Postgres is quite picky on when to use a 'double quote' and when to use a 'single quote'. Typically when providing a string you would use a single quote.