Why is the user not being created?

Question

PostgreSQL

I installed postgres on linux mint, logged in as a superuser and try to create a user who has a login / password, and who cannot create a database, can log in, cannot create superusers:

[email protected] ~ $ sudo -i -u postgres
[sudo] password for kalinin: 
[email protected] ~ $ man createuser
[email protected] ~ $ createuser -W qwerty -U qwerty -h localhost -S -R -l -D
Password: 
createuser: could not connect to database postgres: FATAL:  password authentication failed for user "qwerty"
FATAL:  password authentication failed for user "qwerty"

During the creation process, the system asks me to enter some kind of password. I don't understand what password is required, because under the superuser I logged in without any password, but simply by doing this:
[email protected] ~ $ sudo -i -u postgres
Please tell me how can I still create a user?

Answer 1

The key -Uspecifies the login not of the newly created user, but of the user who creates it, under which the utility connects to the DBMS.