Remove postgres and install Postgres 10 (Ubuntu 14.04)

gistfile1.txt

Step1: Take dump of all your databases
pg_dumpall > outputfile

Step2: Uninstall Postgres
dpkg -l | grep postgres

Step3: Get list of all postgres related packages from Step 2 and form purge command
sudo apt-get --purge remove postgresql postgresql-8.3  postgresql-client  postgresql-client-8.3 postgresql-client-common postgresql-common  postgresql-contrib postgresql-contrib-8.3

Step4: Remove all data directories
sudo rm -rf /var/lib/postgresql/
sudo rm -rf /var/log/postgresql/
sudo rm -rf /etc/postgresql/

Step5: Follow the instruction to install Postgres10
https://www.postgresql.org/download/linux/ubuntu/

Step6: If it results with following error, it means PG service is trying to start using systemctl. Generally ubuntu 14 doesnt use systemctl
Failed to issue method call: Unit postgresql@10-main.service failed to load: No such file or directory. See system logs and 'systemctl status postgresql@10-main.service' for details.

Step7: Tweak the startup scripts to skip systemctl (--skip-systemctl-redirect)
Goto: /usr/share/postgresql-common/init.d-functions
Change this 

    if [ "$1" = "stop" ] || [ "$1" = "restart" ]; then
        ERRMSG=$(pg_ctlcluster --force "$2" "$name" $1 2>&1)
    else
        ERRMSG=$(pg_ctlcluster "$2" "$name" $1 2>&1)
    fi

to
    if [ "$1" = "stop" ] || [ "$1" = "restart" ]; then
        ERRMSG=$(pg_ctlcluster --skip-systemctl-redirect --force "$2" "$name" $1 2>&1)
    else
        ERRMSG=$(pg_ctlcluster --skip-systemctl-redirect "$2" "$name" $1 2>&1)
    fi

Step8: Restart postgres service
sudo service postgresql restart

Step9: Create postgres user and configure it for the first time
i) sudo –u postgres psql postgres
ii) \password postgres
iii) Edit /etc/postgresql/9.3/main/pg_hba.conf and change:
      #Database administrative login by Unix domain socket
       local    all        postgres                               peer

      To:

      #Database administrative login by Unix domain socket
       local    all        postgres                               md5

Step10: Restart postgres service
sudo service postgresql restart

Step11: Restore dump
psql -U postgres < /home/user/bkup1/outfile

References:
https://askubuntu.com/questions/1000631/unable-to-install-postgresql-10-on-ubuntu
https://ubuntuforums.org/showthread.php?t=2277582
https://askubuntu.com/questions/32730/how-to-remove-postgres-from-my-installation