I have setup Ubuntu as a development web server - however I am experiencing problems with file permissions. I have 2 users, user1 and user2, and they both have been put into the group www-data.

I have uploaded a new file with user1 so the file is owned by user1 and the www-data group.

At present if user2 wants to modify the permissions on that file to say 777 - they cannot.

Is there a way to allow any users within a group to be able to modifiy permissions etc.. on this file? I have tried changing umask to 002 and a few other combinations that were suggested without luck.