How to install postgres 9.3

Let’s see how to install PostgreSQL 9.3 Server and PGAdmin3 on a clean Ubuntu OS in  detail!

    Install dependency
    Open Terminal and execute the following commands:

    sudo apt-get update
    sudo apt-get -y install python-software-properties

    Add PostgreSQL 9.3 repository
    Before installing PostgreSQL 9.3, we have to add the PostgreSQL repository where the packages are located.
    Setup key:

    wget --quiet -O - https://www.postgresql.org/media/keys/ACCC4CF8.asc | sudo apt-key add -

    Setup repository:
    Run the following command and note down the output. It is the codename of your Ubuntu release.

    lsb_release -c

    Replace the codename in the below command with the one you got from above command and run:

    sudo sh -c 'echo "deb http://apt.postgresql.org/pub/repos/apt/ codename-pgdg main" >> /etc/apt/sources.list.d/postgresql.list'

    Install PostgreSQL 9.3 using aptitude

    sudo apt-get update
    sudo apt-get install postgresql-9.3 pgadmin3

    Accessing Database from Terminal
    Installation of PostgreSQL will automatically create a Unix/Ubuntu user, named postgres. We will have to login with this user in order to perform various database activities such as accessing database, taking and restoring backups, starting/stopping server etc.
    We may need to reset the password for postgres user before we are able to login to that account.

     The UNIX user, postgres is locked by default. Changing the password for this user will unlock the account. It is not preferred and even considered as a serious security threat.

    To start with PostgreSQL, you can connect to the default database using the following command:

    sudo -u postgres psql

    For other activities like taking data base dump, you have to login as postgres UNIX user as shown below(assuming you have root user privileges):

    sudo su postgres

    Accessing Database from pgAdmin
    Just like the Unix user, PostgreSQL will also create a database user named postgres, which we should use for login to database for the first time.
    To be able to access database from pgAgent3, we should follow either one of the following two options:

        Change the password for the postgres DB user
        Change the database access rights  in the pg_hba.conf file

    We will proceed with the second method, since setting password for postgres DB user is not preferred.
        After loging into postgres DB in terminal, run the following command to get the path to your pg_hba.conf file

        show hba_file ;

        In my case it returned: /etc/postgresql/9.3/main/pg_hba.conf
        Open the file using any text editors

        sudo gedit /etc/postgresql/9.3/main/pg_hba.conf

        And replace the two lines mentioned below:

        local   all             all                                    md5

        to

        local   all             all                                    trust

        And

        host    all             all             127.0.0.1/32            md5

        to

        host    all             all             127.0.0.1/32            trust

        If you are not able to find any lines similar to above two lines, adding the substitute lines at the top of the file will also do the job.
        Restart PostgreSQL server once.

    If you want more information about the pg_hba.conf file and its contents, you can read it here or here.
    That’s it!  You’ve installed PostgreSQL 9.3 on Ubuntu and now you can use pgAdmin3 to login to your database with any password.