rsync - Mar 2010 - copying differences to different directory

sorry for the confusing subject line.  i couldn't think of a better way to
say it.

i'm wondering if rsync can perform the following action:

Compare contents of Directory A (master) to Directory B and copy any differences
from Directory A to Directory C (example below)

Directory A:
foo
bar
biz
nis
sum
tin

Directory B:
foo
biz
nis
sum

Directory C:
(empty prior to rsync operation)
bar
tin
(both bar and tin copied from Directory A)

Any assistance that can be provided will be, of course, very appreciated.

--john

On Tue, 2010-03-02 at 08:47 -0800, js_spamfree-rsync at yahoo.com
wrote:
> sorry for the confusing subject line. i couldn't think of a better way
> to say it. 
> 
> i'm wondering if rsync can perform the following action:
> 
> Compare contents of Directory A (master) to Directory B and copy any
> differences from Directory A to Directory C (example below)
You want --compare-dest.

Note that --compare-dest is based on the quick check, which uses size
and mtime by default.  If you have files in A that are identical to the
ones in B except for mtime and you want to omit such files from C,
you'll need to use --checksum /and/ make sure not to preserve mtimes.

-- 
Matt