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From: dente@els.uucp (Colin Dente)
Newsgroups: comp.unix.wizards
Subject: Re: Help with tar
Message-ID: <6042@ux.cs.man.ac.uk>
Date: 5 May 89 13:01:23 GMT
References: <2175@wpi.wpi.edu> <4848@macom1.UUCP>
Sender: news@ux.cs.man.ac.uk
Reply-To: dente@els.ee.man.ac.uk (Colin Dente)
Organization: University of Manchester, UK
Lines: 49

In article <4848@macom1.UUCP> larry@macom1.UUCP (Larry Taborek) writes:
>From article <2175@wpi.wpi.edu>, by gshapiro@wpi.wpi.edu (Gregory N. Shapiro):
>> I am trying to make a tape archive of a directory and a file using tar
>> on an Encore MultiMax.  The first part comes out successful:
[...stuff deleted...]

>lets say that ct0 is your tape driver.  If so, then nct0 would be
>the No-rewind tape driver.  To put on your origional archive you
>would type:
>
>tar -cf /dev/nct0 gshapiro
>
>Then to add another tar archive to the tape:
>
>tar -cvf /dev/ct0 /usr/spool/mail/gshapiro
From the gist of the original article, I get the impression that Greg
was talking about adding new files to the tape at different times, so
it would be a good idea to make sure you step the tape past the first
file before writing the second!

Whilst you could do the tar tvf /dev/nct0 that Larry suggests for
extracting the second file, it would be much neater (and quicker?) to
use mt to control the tape drive.  i.e. to writ the second file:

mt -f /dev/nct0 fsf1 ;           # Steps tape over first file
tar cvf /dev/ct0 /usr/spool/... ;# write the second file

And then to extract the second file, just do what Larry said, but use
mt again.
>
>Note that this does not add to a tape
>archive, but instead puts a second tape archive after the first.
Indeed, and vey messy it can get.  Why, oh why can't I rely on tar
being able to append to a file?

Ho hum

Colin


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