The u-flag stands for the user who owns the file. In your case root. The 'g'-flag stands for the group it belongs to and 'o' for all other users. That was the short explanation, now the long one:


if you type 'ls -l' you get something like this:
-rw-r--r-- 1 root root 0 2005-01-21 20:46 test

The owner of the file 'test' is root and it belongs to the group root. The first - means that it is a file (a directory would show a d). -rw-r--r-- means that it is read- and writable for the owner (root), readabale for the group it belongs to and readable for all other users.

If you now type 'chgrp users test ' and 'chmod g+w test' you get this:
-rw-rw-r-- 1 root users 0 2005-01-21 20:46 test

Now the file belongs to the user root and the group users. The group users has now write-access to the file (if not every user should have write-access you can change the ownership to an other group). I think, that's what you wanted.

P.S.: If you want to change the owner of a file you can use the command 'chown nameofuser nameoffileordirectory'