Here I am Sharing the Step By Step procedure of ODOO 11 Installation. Change the version and dependency accordingly.

If Python is already installed, make sure it is 3.5 or above that, previous versions are not compatible with Odoo 11

Open the terminal and execute below commands step-by-step to achieve excellence:

Step 1: 

Update apt source-lists:

sudo apt-get update

Step 2: 

Create the Odoo user that will own and run the application

sudo adduser --system --home=/opt/odoo --group odoo

Step 3: 

Install and configure the database server, PostgreSQL

sudo apt-get install -y postgresql postgresql-contrib

Once the PostgreSQL is installed, next we set up a new PostgreSQL user for our application. This user will be used for making all the database interaction from the Odoo.

sudo service postgresql start

sudo su - Postgres

createuser --createdb --username postgres --no-createrole --no-superuser --pwprompt odoo
Enter password for new role: *****
Enter it again:*****

Finally exit from the Postgres user account:

exit

FIX 2: Check if your PostgreSQL has proper encoding(UTF-8) or not, used in Odoo Application, if not you can do like this:

sudo su - postgres
psql
update pg_database set encoding = pg_char_to_encoding('UTF8');
\q
exit

FIX 3: Set The Locale To UTF-8 For Python 3, if you are getting UnicodeEncodeError /UnicodeDecodeError, you can fix it, as You can also check this LINK

Directly execute these commands:

locale-gen en_US.UTF-8

export LANG=en_US.UTF-8 LANGUAGE=en_US.en LC_ALL=en_US.UTF-8

FIX 4: In PostgreSQL, allow TCP connection, if you are getting error like:

psycopg2.OperationalError: FATAL: Peer authentication failed for user

To fix it,in /etc/postgresql/9.5/main/pg_hba.conf change peer to md5:

# "local" is for Unix domain socket connections only
local     all all     peer md5

Then

sudo service postgresql restart

Step 5: 

Install the necessary Python libraries & other needed libraries needed for the application:

Odoo 11 will use python 3.5(which is pre-installed on our Ubuntu), previously it uses python 2.7, so to install all dependent libraries easily we`ll install pip3 in our server, as:

sudo apt-get install -y python3-pip

Once pip3 is installed on your server, we can proceed with installing other dependent libraries using pip3 as:

pip3 install Babel decorator docutils ebaysdk feedparser gevent greenlet html2text Jinja2 lxml Mako MarkupSafe mock num2words ofxparse passlib Pillow psutil psycogreen psycopg2 pydot pyparsing PyPDF2 pyserial python-dateutil python-openid pytz pyusb PyYAML qrcode reportlab requests six suds-jurko vatnumber vobject Werkzeug XlsxWriter xlwt xlrd Pypdf2

or after cloning ODOO Source in step 6 do:

pip3 install wheel

pip3 install -r path_to_odoo_folder_source/requirements.txt

Next is to install Odoo Web Dependencies:

sudo apt-get install -y npm
sudo ln -s /usr/bin/nodejs /usr/bin/node
sudo npm install -g less less-plugin-clean-css
sudo apt-get install -y node-less

Once all the packages are installed we are ready to proceed with installing Odoo server.

Step 6:

Installing ODOO version 11 Community Edition hosted on GITHUB.

Make sure you have GIT installed on your system and if not then install with the simple command:

sudo apt-get install -y git

Switch to the Odoo user:

sudo su - odoo -s /bin/bash

Clone the latest branch of Odoo, in our case it is 11.0 from Github:

git clone https://www.github.com/odoo/odoo --depth 1 --branch 11.0 --single-branch .

(This might take a little while depending on the speed of your Internet connection.)

Finally exit from the odoo user account:

exit

Step 7:

The next step is to create a configuration file for Odoo. But before doing so we'll first create the directory for storing logs of Odoo server and assigning proper ownership to the directory:

sudo mkdir /var/log/odoo

sudo chown odoo:root /var/log/odoo

Next is to create the configuration file for the odoo server. Odoo application will use these configurations to run so fill in the configuration as per your requirements.

sudo nano /etc/odoo-server.conf

A sample configuration file will look like this:

[options]
; This is the password that allows database operations:
; admin_passwd = admin
db_host = False
db_port = False
db_user = odoo
db_password = False
logfile = /var/log/odoo/odoo-server.log
addons_path = /opt/odoo/addons,/opt/odoo/odoo/addons

(* You need to use the same password you used back in step 3.)

Once the configuration file is created we will set the ownership rights

sudo systemctl daemon-reload

sudo systemctl start odoo11

sudo systemctl status odoo11

If successful you will get output something like below.

odoo11.service - Odoo11
   Loaded: loaded (/etc/systemd/system/odoo11.service; disabled; vendor preset: enabled)
   Active: active (running) since Thu 2018-05-03 21:23:08 UTC; 3s ago
 Main PID: 18351 (python3)
    Tasks: 4 (limit: 507)
   CGroup: /system.slice/odoo11.service
           └─18351 /opt/odoo/odoo11-venv/bin/python3 /opt/odoo/odoo11/odoo-bin -c /etc/odoo11.conf

if there are no errors you can enable the Odoo service to be automatically started at boot time.

sudo systemctl enable odoo11

to see the messages logged by the Odoo service you can use:

sudo journalctl -u odoo11

Step 8:

Installing the boot script

For the final step, we need to install a script that will be used to start-up & shut-down the Odoo server automatically, with the correct user.

Please Check The Link.

ODOO BOOT SCRIPT

 https://www.odoo.com/documentation/13.0/setup/install.html

https://www.postgresql.org/

​https://webkul.com/blog/setup-locale-python3/

Hi,

There is lot of blogs/writings available over the net on the same, see: How to Install Odoo 12

Thanks

For the final step, we need to install a script that will be used to start-up & shut-down the Odoo server automatically, with the correct user.