cross-device copying / USB improvements

[benny]

benny wrote:

> -> cp resumes. i.e. starts copying the same things again, this time
>    behaving like rsync (I guess rsync solves incomplete transfers by
>    some kind of checksum / hashing)
perhaps this one is not so far away :)
lets say the fs on both devices is hammer, then a cp could be thought of as
a simple mirroring (syncing) (and a mv as a cp with deletion on the
source). the only thing needed would be to be able to "mirror" a single
file and to "detach" the mirrored file / directory somehow from the master.
I don't know if it is possible to extend hammer that way though.

For other filesystems an rsync something would still be needed, but this
could be a start.

Regards,
Benny