I just installed a Bitnami Ruby Stack (Ubuntu, Rails, Rub, ...).
I would like to install postgreSQL.

I tried the following command:

sudo apt-get install postgresql

But, I get this:

    Reading package lists... Done

    Building dependency tree

    Reading state information... Done

    Package postgresql is not available, but is referred to by another package.

    This may mean that the package is missing, has been obsoleted, or

    is only available from another source

UPDATE1

I tried this:

sudo apt-get install postgresql-9.1

And got this:

    The following packages have unmet dependencies:

    postgresql-9.1 : Depends: libldap-2.4-2 (>= 2.4.7) but it is not installable

     Depends: libpq5 (>= 9.1~) but it is not going to be installed

     Depends: postgresql-client-9.1 but it is not going to be installed

     Depends: postgresql-common (>= 115~) but it is not installable

     Depends: ssl-cert but it is not installable

     E: Unable to correct problems, you have held broken packages.

UPDATE2

This is the first time I have logged on via terminal from my iMac. I guess I'm in a user directory. What directory do I need to be in for the install to work?

Thanks for the help!!