Something wrong on making default connection to your server. I would suggest try to connect default database as postgres user using psql; which will let you know if there is connection problem. Once you resolved 'default' connection problem, 'createuser' will work fine.
On Mon, Sep 4, 2017 at 12:40 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
tirveni yadav <yadav.tirveni@gmail.com> writes: > On Mon, Sep 4, 2017 at 7:41 PM, Ramesh <ramesh4f@gmail.com> wrote: >> [postgres@localhost ~]$ createuser mytest >> Password: >> createuser: could not connect to database postgres: FATAL: password >> authentication failed for user "postgres"
> This could be due to enabling md5 authentication for user postgres. > And password not yet set up for the user postgres.
On most Linux distros, the default setup is that the postgres database user has no password --- if it did, everybody and his brother would try that password first if they wanted to break into a database :-(. Rather, it's typically set up so that if you are logged in as the operating system's postgres user, as Ramesh seems to be, it will let you in automatically based on peer authentication. So it's not clear why that's not working. Looking at the pg_hba.conf file to see what the actual authentication setup is would be a good thing.
One idea is that there's a PGHOST environment variable setting that is affecting how createuser thinks it should connect. Peer auth only works when you come in through a Unix socket.