I just want to move dirs. I looked successively at mv, cp and rsync, since each tool in turn didn't seem to have the option to remove directories from source after copying them. For instance, mv needs files, not dirs, when src and dst are on different devices:
"inter-device move failed: src to dst; unable to remove target: Is a directory"
Perhaps the simplest way to do this is by using an additional deletion cmd, although I'd prefer not to use it, since that increases risk of data loss.