So, for a user belonging to group "XYZ", he can't read the files under "sample" folder ?
No. The file and directory permissions for others is read-only. So any user can view the files.
Similarly, for a user in "OPQ" group, they should be able to read "data1" file, but why can he do that while he doesn't belong to "XYZ" group at all
A user can belong to multiple groups. Also, there is nothing blocking users from the directory -- everyone has read access to the directory. Group and Other don't have "x" permission on the directory which mean they can't enumerate the files in the directory. But if given the file name, they can read the file.
[ November 27, 2006: Message edited by: Scott Johnson ]