unable to create user postgres: role "postgres" does not exists

Question

i am on ubuntu 12.04 server and i am trying to install postgresql. As of now, i have successfully installed it but unable to configure it. I need to create a role to move ahead and i ran this command in terminal :

root@hostname: createuser -s -r postgres

and it said :

createuser: could not connect to database postgres: FATAL: role "root" does not exist

Fine, so i did :

su - postgres

and then tried again

postgres@hostname: createuser -s -r postgres

and i got the error

createuser: could not connect to database postgres: FATAL: role "postgres" does not exist

and i get the same error when i do

psql -d dbname

Its like a loop, i am unable to create a role postgres because a role postgres does not already exist.

How do i fix this ?

The postgres version seems to be 9.1.x and the ubuntu version is 12.10

Answer 1

Turns out i had installed postgres-xc and postgresql on my machine. I had to knock off postgres-xc completely. And it was a little difficult to do that because, there was always an error --purge remove postgres-xc and the uninstallation could not continue.

There seems to be some kind of a packaging bug. (details on launchpad).

Eventually, i ended up doing this to make it work.

After that i uninstalled postgresql and installed it back to make it work.

Answer 2

Read postgresql tutorial it doesn't matter if it's Ubuntu or other Linux.

EDIT before creating role or anything else on fresh install you need to create database cluster: have you created it?

initdb -D /usr/local/pgsql/data

You need to be logged as user postgres on linux machine. Here is more info.