Nsryjdtyk

The key is "I installed the postgres.app for mac." This application sets up the local PostgreSQL installation with a database superuser whose role name is the same as your login (short) name.

When Postgres.app first starts up, it creates the $USER database,
which is the default database for psql when none is specified. The
default user is $USER, with no password.

Some scripts (e.g., a database backup created with pgdump on a Linux systsem) and tutorials will assume the superuser has the traditional role name of postgres.

You can make your local install look a bit more traditional and avoid these problems by doing a one time:

/Applications/Postgres.app/Contents/Versions/9.*/bin/createuser -s postgres

which will make those FATAL: role "postgres" does not exist go away.

For MAC:

1. Install Homebrew


2. brew install postgres


3. initdb /usr/local/var/postgres


4. 
   /usr/local/Cellar/postgresql/<version>/bin/createuser -s postgres or /usr/local/opt/postgres/bin/createuser -s postgres which will just use the latest version.


5. start postgres server manually: pg_ctl -D /usr/local/var/postgres start
   

To start server at startup

• mkdir -p ~/Library/LaunchAgents


• ln -sfv /usr/local/opt/postgresql/*.plist ~/Library/LaunchAgents


• launchctl load ~/Library/LaunchAgents/homebrew.mxcl.postgresql.plist

Now, it is set up, login using psql -U postgres -h localhost or use PgAdmin for GUI.

By default user postgres will not have any login password.

Check this site for more articles like this: https://medium.com/@Nithanaroy/installing-postgres-on-mac-18f017c5d3f7

createuser postgres --interactive

or make a superuser postgresl just with

createuser postgres -s

For me, this code worked:

/Applications/Postgres.app/Contents/Versions/9.4/bin/createuser -s postgres

it came from here:
http://talk.growstuff.org/t/fatal-role-postgres-does-not-exist/216/4

First you need create a user:

sudo -u postgres createuser --superuser $USER

After you create a database:

sudo -u postgres createdb $USER

Change $USER to your system username.

You can see the the complete solution here.

I needed to unset $PGUSER:

$ unset PGUSER

$ createuser -s postgres

Running this on the command line should fix it

/Applications/Postgres.app/Contents/Versions/9.4/bin/createdb <Mac OSX Username Here>

Dropping the postgres database doesn't really matter. This database is initially empty and its purpose is simply for the postgres user to have a kind of "home" to connect to, should it need one.

Still you may recreate it with the SQL command CREATE DATABASE postgres;

Note that the tutorial mentioned in the question is not written with postgres.app in mind.
Contrary to PostgreSQL for Unix in general, postgres.app tries to look like a normal application as opposed to a service that would be run by a dedicated postgres user having different privileges than your normal user. postgres.app is run and managed by your own account.

So instead of this command: sudo -u postgres psql -U postgres, it would be more in the spirit of postgres.app to just issue: psql, which automatically connects to a database matching your users's name, and with a db account of the same name that happens to be superuser, so it can do anything permissions-wise.

For what it is worth, i have ubuntu and many packages installed and it went in conflict with it.

For me the right answer was:

sudo -i -u postgres-xc

psql

This is the only one that fixed it for me :

createuser -s -U $USER

On Ubuntu system, I purged the PostgreSQL and re-installed it. All the databases are restored.
This solved the problem for me.

Advice - Take the backup of the databases to be on the safer side.

I don't think that sudo is needed here because psql -l returns a list of databases. This tells me that initdb was run under the user's current user, not under the postgres user.

You can just:

psql

And continue the tutorial.

I would suggest A.H's general points of creating the postgres user and db because many applications may expect this to exist.

A brief explanation:

PostgreSQL will not run with administrative access to the operating system. Instead it runs with an ordinary user, and in order to support peer authentication (asking the OS who is trying to connect) it creates a user and db with the user that runs the initialization process. In this case it was your normal user.

I became stuck on this issue having executed brew services stop postgresql the day prior.
The day following: brew services start postgresql would not work. This is because as is shown when you install using homebrew. postgresql uses a launchd ... which loads when your computer is powered on.

resolution:
brew services start postgresql
Restart your computer.

The du command return:

Role name = postgres@implicit_files

And that command postgres=# password postgres return error:

ERROR: role "postgres" does not exist.

But that postgres=# password postgres@implicit_files run fine.

Also after sudo -u postgres createuser -s postgres the first variant also work.