The actual use case: I have an emulator that uses a directory as the ‘system disk’ of the computer being emulated, but I have one of these on each of two machines. As I make updates I want to have the proper files updated on the other directory so between changes on the two emulators the most recent is synced to the other directory.
It seems I will need to use 2 rsync commands, one in each direction. Update A from B, then update B from A.