>I'm using VFP programs in a LAN and some file have to be shared. Is there a command I could use within VFP to make the folder a shared folder so that others could access through LAN (I don't want to share file outside of VFP, to avoid accidental erasure).
>

Sharing is accomplished externally to VFP; it's an OS function. For a VFP app to use shared resources, the OS must make them available.

You could creatre a COM object to perform specific tasks within the folder on behalf of other clients - the clients submit requests via method calls and receive back the results, never accessing the files directly by themselves, but that means that all actions that might need to be performed must be implemented in and published through the COM server. A web service could provide similar functionality, but again, the scope of published methods limit what you'll be able to do - you won't be able to directly act on the files in the folder, only via proxy through the server application.