This works, but only under very restrictive circumstances. First, the users have to include the alias (or shell function) in their .bashrc; secondly, it would not work in the scripts invoked by the users (unless they are bash scripts and also the bash script also reads .bashrc, not a very common situation). Finally, it works reliably only if the user consistently uses cp to copy the file, and not some other command (such as cat or some Perl program using File::Copy).
So, in the end, it depends very much on the cooperation of the users....
Ronald Fischer <email@example.com>