sudo passwd www-data

choose a password

su www-data

login with choosen password

cp -R index.php /var/www/html

cd /var/www/html

chmod u+rw index.php

sudo apt install apache2 

sudo service apache2 start

open firefox and type : 

localhost 

or 

https://127.0.0.1/

Results: 

https://127.0.0.1/results.txt