--timeout=TIME set IO timeout in seconds
-I, --ignore-times turn off mod time & file size quick check
--size-only ignore mod time for quick check (use size)
- --modify-window=NUM use if mod times have reduced accuracy
+ --modify-window=NUM compare mod times with reduced accuracy
-T --temp-dir=DIR create temporary files in directory DIR
--compare-dest=DIR also compare received files relative to DIR
--link-dest=DIR create hardlinks to DIR for unchanged files