Install i810switch by entering the following commands in the terminal:
sudo apt update sudo apt install i810switch
Description:
Enables/disables video output to CRT/LCD on i810 video hardware
i810switch enables/disables the output to the CRT display and LCD, depending on the i810 graphics controller hardware. Such hardware is found on some laptops (eg, Sony Vaios, some Dell models, etc). Chipsets also supported include i855, i830, i845. . This package includes the i810rotate script, which toggles the output between three states: LCD only, LCD + CRT, and CRT only.
Homepage: http://juljas.net/vaio
Version: 0.6.5-7.1build1
Section: universe/utils