How to purge and reinstall postgresql on ubuntu?

Somehow I managed to completely bugger the install of postgresql on Ubuntu. Now I want to start over from scratch, but when I "purge" the package with apt-get it still leaves traces behind such that the reinstall configuration doesn't run properly.

After I've done:

apt-get purge postgresql
apt-get install postgresql

It said

Setting up postgresql-8.4 (8.4.3-0ubuntu9.10.1) ...
Configuring already existing cluster (configuration: /etc/postgresql/8.4/main, data: /var/lib/postgresql/8.4/main, owner: 108:112)
Error: move_conffile: required configuration file     /var/lib/postgresql/8.4/main/postgresql.conf does not exist
Error: could not create default cluster. Please create it manually with

  pg_createcluster 8.4 main --start

or a similar command (see 'man pg_createcluster').
update-alternatives: using /usr/share/postgresql/8.4/man/man1/postmaster.1.gz to provide /usr/share/man/man1/postmaster.1.gz (postmaster.1.gz) in auto mode.

Setting up postgresql (8.4.3-0ubuntu9.10.1) ...

I have a "/etc/postgresql" with nothing in it and "/etc/postgresql-common/" has a 'pg_upgradecluser.d' directory and root.crt and user_clusters files.

The /etc/passwd has a postgres user; the purge script doesn't appear to touch it. There's been a bunch of symptoms which I work through only to expose the next.

Right this second, when I run that command "pg_createcluster..." it complains that '/var/lib/postgresql/8.4/main/postgresql.conf does not exist', so I'll go find one of those but I'm sure that won't be the end of it.

Is there not some easy one-liner (or two) which will burn it completely and let me start over?


First: If your install isn't already damaged, you can drop unwanted PostgreSQL servers ("clusters") in Ubuntu using pg_dropcluster. Use that in preference to a full purge and reinstall if you just want to start with a freshly initdb'd PostgreSQL instance.

If you really need to do a full purge and reinstall, first make sure PostgreSQL isn't running. ps -C postgres should show no results.

Now run:

apt-get --purge remove postgresql\*

to remove everything PostgreSQL from your system. Just purging the postgres package isn't enough since it's just an empty meta-package.

Once all PostgreSQL packages have been removed, run:

rm -r /etc/postgresql/
rm -r /etc/postgresql-common/
rm -r /var/lib/postgresql/
userdel -r postgres
groupdel postgres

You should now be able to:

apt-get install postgresql

or for a complete install:

apt-get install postgresql-8.4 postgresql-contrib-8.4 postgresql-doc-8.4

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