>Periodically we need to update an APP on the server, but is in use by one or two people only.
>Is there anyway to tell who is using an APP on the server?

First of all, for the main program, you would typically use an EXE, not an APP. That way, you don't need to install VFP for all the users (and pay the corresponding licenses). (However, you might still use an APP called from an EXE.)

Also, you don't really need to ask your users to exit! For the main program, I use the following approach, which you might also use for a sub-programm in an APP:

Each time the EXE (or APP) is updated, I save it with a different name, reflecting the version number: MyApp_0001.exe, MyApp_0002.exe, etc.

A small loader program will detect the latest version, and load it.

The relevant commands are adir(), to get the filename, substr() and val(), to get the version number, and RUN, to execute the file.

HTH,

Hilmar.