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Find current apache users & groups
ps aux | grep apache

find out groups this specific user belongs to 
groups username

create a new user
sudo addgroup groupname

Add user to a group
sudo adduser username groupname

change directory ownership to specif user and group
sudo chown -R user:group directory

set permissions on directory so all new files/folders inherit same ownership as parent
chgrp www-data /some/dir
chmod g+s /some/dir