Wsrtjtyk

I am running centOS 7 and trying to create a postgresql database

I entered to following to install and initiate database

yum install https://download.postgresql.org/pub/repos/yum/11/redhat/rhel-7-x86_64/pgdg-centos11-11-2.noarch.rpm



sudo yum install postgresql11



sudo yum install postgresql11-server



sudo /usr/pgsql-11/bin/postgresql-11-setup initdb



sudo systemctl enable postgresql-11



sudo systemctl start postgresql-11

so after this i try to create a database by entering

sudo createdb mydb

receive:

createdb: could not connect to database template1: FATAL:  role "root" does not exist

so now i realize i need to be on the postgre user

and cannot create a db with this command:

sudo -u postgres createdb mydb

Recieve:

could not change directory to "/home/<user>": Permission denied

I am able to get the postgre prompt by entering the following

sudo -u postgres -i

psql

but when i enter sudo -u postgres -1 i get a new bash prompt -bash-4.2$

when i try to create a database in this prompt with sudo createdb mydb it asks for a password for postgres and can't go on from there,
what is this password? i read that by default it shouldn't

Did you try
sudo -i -u postgres
psql CREATE DATABASE yourbase;
c yourbase ?