Hardlink sub-directories and files

[loial]

I am trying to hardlink all files in a directory structure using
os.link.

This works fine for files, but the directory also contains sub-
directories (which themselves contain files and sub-directories).
However I do not think it is possible to hard link directories ?

So presumably I would need to do a mkdir for each sub-directory
encountered?
Or is there an easier way to hardlink everything in a directory
structure?.

The requirement is for hard links, not symbolic links