Hi, in https://docs.moodle.org/405/en/Step-by-step_Installation_Guide_for_Ubuntu

and in https://docs.moodle.org/405/en/Installing_Moodle_on_Debian_based_distributions

it says:

chown -R www-data:www-data moodle

and

sudo chown -R www-data:www-data /var/www/html/moodle

Its better that the web server can only read that files (not write), it's best the reccomendation that is already made in

https://docs.moodle.org/405/en/Installation_quick_guide

"Check the permissions and make sure that the web server does not have permissions to write to any of the files in the Moodle code directories (a very common root cause of sites being hacked)."

Regards

Emilio