Usually, when postgres is installed a service/daemon is created in the system so, there is no need to launch the server by hand. You are getting the error because the service is already running.
Try to connect to the database using psql
Usually, when postgres is installed a service/daemon is created in the system so, there is no need to launch the server by hand. You are getting the error because the service is already running.
Try to connect to the database using psql