This script is based on the install script from André Schenkels (https://github.com/aschenkels-ictstudio/openerp-install-scripts) but goes a bit further and has been improved. This script will also give you the ability to define an xmlrpc_port in the .conf file that is generated under /etc/ This script can be safely used in a multi-odoo code base server because the default Odoo port is changed BEFORE the Odoo is started.

You have to enable universe category which contains python-pip package. Open /etc/apt/sources.list using an editor, for example nano:

sudo nano /etc/apt/sources.list

then add universe at the end of each line, like this:

deb http://archive.ubuntu.com/ubuntu bionic main universe
deb http://archive.ubuntu.com/ubuntu bionic-security main universe 
deb http://archive.ubuntu.com/ubuntu bionic-updates main universe

then run:

sudo apt update

sudo wget https://raw.githubusercontent.com/onesteinbv/InstallScript/12_os_18.04/odoo_install.sh

There are a few things you can configure, this is the most used list:
OE_USER will be the username for the system user.
INSTALL_WKHTMLTOPDF set to False if you do not want to install Wkhtmltopdf, if you want to install it you should set it to True.
OE_PORT is the port where Odoo should run on, for example 8069.
OE_VERSION is the Odoo version to install, for example 12.0 for Odoo V12.
IS_ENTERPRISE will install the Enterprise version on top of 12.0 if you set it to True, set it to False if you want the community version of Odoo 12.
OE_SUPERADMIN is the master password for this Odoo installation.

sudo chmod  x odoo_install.sh

export LC_ALL="en_US.UTF-8"
export LC_CTYPE="en_US.UTF-8"
sudo dpkg-reconfigure locales
sudo ./odoo_install.sh