Rsync opens source file in read only mode - so it has the same probability to modify a file that regular copying does. That said, the --remove-source-files opti

Rsync opens source file in read only mode - so it has the same probability to modify a file that regular copying does. That said, the --remove-source-files option will delete source files after copying; --delete may remove destination files; and used together they drop the idempotence guarantee that rsync gives. So you have to be careful. Re changing file - IIRC it will keep Resending until file size+mtime at end of transfer is same as in the beginning.