I currently know how to copy files that don't exist in the target directory. This allows me to copy from src to dst just as I would like.
However, now I want to copy from src to dst/2016-01-05 BUT only the files in src that do not exist anywhere inside dst.
Example
Suppose the start situation is
src/f1.txt
src/f2.txt
src/f3.txt
dst/2016-01-04/f1.txt
dst/2016-01-05/f0.txt
Then, after doing the copy, the end situation should be:
src/f1.txt
src/f2.txt
src/f3.txt
dst/2016-01-04/f1.txt
dst/2016-01-05/f0.txt
dst/2016-01-05/f2.txt
dst/2016-01-05/f3.txt
In general I would not like to overwrite existing files. Even if the source is updated.