cpio/afio writing directories?

[The Super User]

I'm using afio (operationally very like cpio, for those who've never
seen afio; if you use cpio and don't have afio, get afio!) to back up
a SCO Xenix file system. But I doubt that the system type matters any.

Basically, it seems that cpio/afio, unlike tar, require real file names,
not just directory names... such that:

% tar cf tarfile /x /y /z

will back up the directories /x /y /z and all their files and
subdirectories, but:

% echo '/x /y /z' | afio -o archive

will simply create information about the *directories* /x /y /z on the
archive, and *not* backup the files and subdirectories in them! It becomes
necessary to use:

% echo /x/* /y/* /z/* | afio -o archive

to convince afio/cpio to do the directories and everything underneath
(afio/cpio *do* take a directory in a listed file's subdirectory as
'back this and its children up also', e.g. /x/* including /x/aa *will*
get /x/aa/* backed up, &etc...)

My question: How do I tell afio/cpio that 

% echo '/x /y /z' | afio -o

means /x /y /z and all subfiles also?

Thanks!
Jay Libove (Jay.Libove at andrew.cmu.edu  or  pitt!darth!libove!libove)
-- 
Jay Libove (Jay.Libove at andrew.cmu.edu  or  pitt!darth!libove!libove)