With a friend of mine we were trying to install and configure PostgreSQL. Practicing to make experience.

And while an uninstall process we experienced some problems. Maybe this was because internet connection was not running well that time. And maybe we wanted to remove the packages when the server was still running. We forgot to give the command: /etc/init.d/postgresql8.1 stop

Finally now after our last efforts we think that we have removed postgresql successfully.

Also now when we want to install postgres by running the following command-line

And the screen output is similar to the following:

We removed the configuration folders with root priviliges to remove all existing configuration files:
/etc/postgresql
/etc/postgresql-common

But the problem still continues...

Thanks for all the help.

you can try apt-get install -f postgresql-8.1 postgresql-client-8.1