What about this. You create a directory with the permissions. This was only 
the 5 Users can enter the directory.

drwxr-x---   2 mainact    5users        4096 Mar 22 23:28 Directory/

The the file will have the permissions.

-rwxrwxr--   1 mainact    4users       39025 May 26 11:44 Special_file.txt

This way the people in group 5users and enter the directory and use the 
"OTHER" permissions to read the file. The four that need write can also be 
entered into group 4users which have the group permissions to write.

Now the "OTHER" permission on the file may be deciving, but no prying eyes 
will be able to read it without being able to execute the directory. The only 
people who can execute the directory is the 5users.

On Tuesday 23 July 2002 05:41 am, George Toft wrote:
> I was given this puzzle, and told it cannot be solved using Unix:
>
> You have a file that needs protected from prying eyes.  You must allow
> only 5 people read access, and 4 people read/write access.  The rest of
> the world cannot be allowed to view it.  What set of Unix permissions
> and ownership can support this?
>
> George
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