Issue
For directory /var/www/ and its subdirectories, I wish users apache, phped, and Michael each to have r/w/x privileges on all existing files as well as future files created by each of these users. How should I do this?
Solution
You either want to put all those users in a group and set the group ownership of /var/www to that group. Then you'd want to set the group suid bit with something like chmod g+rwxs dirname to make all new files belong to the group.
Or you could use ACLs (Access Control Lists) see for example http://users.suse.com/~agruen/acl/linux-acls/online/ To make all new files belong to some certain group you can set the default ACL for the folder and all new files
[edit]
You create a new group groupadd mynewgroup and then useradd -G mynewgroup Michael and so on for all the users that should be in that group. Then you'll need to chgrp -R mynewgroup /var/www/ to set the group ownership of the directory.
Answered By - evading Answer Checked By - Senaida (WPSolving Volunteer)