cpio

[Wolf Paul]

In article <625 at mccc.UUCP> pjh at mccc.UUCP (Peter J. Holsberg) writes:
>
>Do cpio and ctccpio always overwrite anything that is already on the
>diskette or tape?  If so, is there any 'copy' program that does not?
>Thanks.

Cpio and things like tar don't check to see if there is data; you need to keep
track of what's on the medium you're using.

Most tape drivers call a single contiguous recording of data a "volume"
or (BSD4.2) a "file system"; most drivers come with a user command to
position the tape after a specified volume or file system (i.e. BSD4.2
the command is "fsf").

If your driver does not support this, or if you are using disks, you can
somehow keep track of how much data is on a given disk or tape and then
use some kind of "skipping" filter to write your cpio output. There was
such a program posted to comp.sources.misc a few months ago, I think
it was called "bundle".

Basically such a program opens the device in read/write mode, and reads
or seeks the specified number of bytes before writing its standard input
to its standard output.
-- 
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