Ok, thank you. That greatly simplifies things, and I appreciate the effort to answer each question. I was mainly unsure about edge cases, but it seems the syncing is fairly shallow. And obviously in finding the masterfile, the program can be terminated earlier, so it doesn't have to rely on the systemcall if something has conflicting types. And yeah, using the most recent modification time is my current implementation, but again, just checking edge cases. Yeah, syncing permissions and times for directories would be slightly harder, although since my code recursively processes directories, the final part of the function could just change the permissions. Thanks