Follow the below steps to install Odoo 13 on Ubuntu 18.04

Here is the step by step description to install Odoo into ubuntu, use the commands available in these steps to configure it to be operational.

Step 1: Update your system

First, you have to update the server or the system. You can update it through the use of the following commands
sudo apt-get updatesudo apt-get upgrade

Step 2: Secure your server

After making sure that the server is up to date, run the below command to make sure the server/system is remotely accessible and secure to operate.
sudo apt-get install openssh-server fail2ban

Step 3: User Creation

The next step is to create a system user for Odoo, you can create a system user by using the command described below:
sudo adduser --system --home=/opt/odoo --group odoo
If you follow the above steps precisely, the source code of odoo will reside in the home directory of the created user.

Step 4: Configure PostgreSQL

Odoo needs PostgreSQL to run properly in a system therefore you have to install and configure the PostgreSQL database server in order to run Odoo 13 in it. You can install PostgreSQL using the following command:
sudo apt-get install postgresql
This will install PostgreSQL on your server.
Furthermore for creating new PostgreSQL users for managing Odoo databases run the below command.
sudo su - postgrescreateuser --createdb --username postgres --no-createrole --no-superuser --pwprompt odoo13
By running the above command a user named Odoo13 will be created. In addition, while running the above command the Postgres will ask you to create and enter a password for the created user.
Further after creating the user, change the user as to superuser using the following command
psqlALTER USER odoo13 WITH SUPERUSER;
After changing the user, use the command “\q” to exit Furthermore, to exit from Postgres user by “exit” command to continue the installation.

Step 5: Installing dependencies for Odoo

After installing and configuring PostgreSQL,  you have to install the dependencies for Odoo.
Install pip3 by running the below command
sudo apt-get install -y python3-pip
After installing pip3, you have to install the other dependencies using the pip3, for that run the below command.
sudo pip3 install Babel chardet decorator docutils ebaysdk feedparser gevent greenlet html2text Jinja2 libsass lxml Mako MarkupSafe mock num2words ofxparse passlib Pillow psutil psycopg2 pydot pyldap pyparsing PyPDF2 pyserial python-dateutil pytz pyusb PyYAML qrcode reportlab requests suds-jurko vatnumber vobject Werkzeug XlsxWriter xlwt xlrd polib
In case, if any error that occurs during the running of the above command or you get a error message, try the command below:
sudo pip3 install Babel chardet decorator docutils ebaysdk feedparser gevent greenlet html2text Jinja2 libsass lxml Mako MarkupSafe mock num2words ofxparse passlib Pillow psutil psycopg2-binary pydot pyldap pyparsing PyPDF2 pyserial python-dateutil pytz pyusb PyYAML qrcode reportlab requests suds-jurko vatnumber vobject Werkzeug XlsxWriter xlwt xlrd polib
After the successful installation of the above dependencies, you have to install some other web based dependencies also. Therefore to install these dependencies run the below commands:
sudo apt-get install -y npmsudo ln -s /usr/bin/nodejs /usr/bin/nodesudo npm install -g less less-plugin-clean-csssudo apt-get install -y node-less
For printing PDF reports, Odoo needs wkhtmltopdf. Moreover, the recommended version of wkhtmltopdf is 0.12.5 that you can download and install to be operational by running the following command:

Source: How to Install Odoo 13 on Ubuntu 18.04