Allow user to edit /var/www

Allow another user to edit a directory in www-data group. The post will be useful when editing files on your local /var/www/ directory. Add user samuil to group www-data:

sudo usermod -a -G www-data samuil

Add user www-data to group samuil:

sudo usermod -a -G samuil www-data

List all users in www-data and samuil groups to be sure that the user is added:

awk -F':' '/www-data/{print $4}' /etc/group

Make sure that the desired directory has the required permisions for the group:

sudo chmod 775 -R /var/www/

Login again to make sure that your user permitions will apply for samuil:

su samuil

Restart your HTTP server to ensure that www-data user has applied permisions:

sudo /etc/init.d/apache2 restart