I would like to synchronise the contents of two directories.

• Without overwriting but to create a copy if two files have the same name, but different sizes
• Without duplicating if two files have the same name and size.
• To work recursively

So far I have found the following command which might work

 $ rsync -varE --progress ~/folder /volumes/server/folder

But I'm not entirely sure what the -E flag does. It was suggested by a user on bananica.com but couldn't see a description for it in the manual. Would this do what I require successfully?

Thanks