To install odoo on debian or ubuntu system connect to your server via ssh and execute commands step-by-step from install-odoo.sh file of this gist:

https://gist.github.com/yelizariev/2abdd91d00dddc4e4fa4

It covers following aspects:

• Installation of a stable odoo version. Odoo will start automatically after rebooting server.
• Longpolling support (for instant messaging inside odoo)
• Autobackup with backups rotating (to save a disk space)
• Nginx port forwarding (to avoid addresses with a port like this: http://example.com:8069/ )
• Multitenancy support (you can create any number databases on a single installation)

You can also fork the gist and modify it according to your needs, just click Fork at gist page and don't forget update GIST variable at install-odoo.sh file.