s/// return value

s/// appears to have scalar context only, and it returns the number of times the substitution was made.

rsync --exclude

The argument to --exclude is a glob not a regexp, so you use * to mean *.

If the argument is a single directory name, put a slash after it.

Argument can be a path fragment, but remember it will be matched against a local path starting from the source/target path specified. If you're not clear what that local path is, you can see it in the output from -n .

And NB that it is --exclude with two dashes. If you only use one dash the setting will be silently ignored.