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From: pim@cti-software.nl (Pim Zandbergen)
Newsgroups: comp.unix.i386,comp.unix.wizards
Subject: Re: multi-volume tar
Keywords: format
Message-ID: <1990Aug30.090147.2866@cti-software.nl>
Date: 30 Aug 90 09:01:47 GMT
References: <7920@lynx.UUCP> <2242@sud509.ed.ray.com>
Organization: CTI Software BV, The Hague, The Netherlands
Lines: 24

heiser@tdw201.ed.ray.com writes:

>The Esix manuals mentions multi-volumes (floppies) in the tar and cpio
>sections -- but I could not get either to work.  Maybe i'm not using the
>right device names or something.  I tried to both 1.2 and 1.44 meg floppies.
>Anyone know of any special tricks to do this?

tar has a -k flag that wil make it count bytes.
tar -cvfbk /dev/dsk/f0q15dt 20 1200 will prompt for the next
floppy after wrinting 1200k.
In fact, tar -cv will do exactly the same, if you have not 
altered /etc/default/tar.

cpio will recognize a write() error
with errno == ENXIO (no such device or address) as an end of medium.
Thus, cpio relies on the device driver to generate this errno.

I can't speak for Esix, but on SCO Xenix and ISC Unix, only the
raw floppy devices will generate this error.
-- 
Pim Zandbergen                          domain : pim@cti-software.nl
CTI Software BV                         uucp   : uunet!mcsun!hp4nl!ctisbv!pim
Laan Copes van Cattenburch 70           phone  : +31 70 3542302
2585 GD The Hague, The Netherlands      fax    : +31 70 3512837