question about TAR

[Felipe Figueiredo]

Em Saturday 01 December 2007 09:43:11 Ouattara Oumar Aziz (alias wattazoum) 
escreveu:
> Felipe Figueiredo a écrit :
> > Em Thursday 29 November 2007 20:14:18 Ouattara Oumar Aziz (alias 
wattazoum)
> > escreveu:
> >> Hello
> >>
> >> I would like to know if it's possible to transfer a file from one tar
> >> archive to another (without untarring it on the disk)
> >>
> >> For example , I have a 2GB dir in a TAR archive and I want to transfer a
> >> subdir of 1GB to another TAR file. I don't have 1GB free on my disk .
> >> Can Tar handle this ?
> >>
> >
> > have you tried this?
> >
> > tar xf archive1.tar relative/path/to/file | tar rf \
> >  archive2.tar -
> >
> >
> Hello, Just tried :
> 
> :~$ tar xf Document.tar Documents/WATTAZOUM.tar.gz | tar rf video.tar -
> tar: -: ne peut stat: Aucun fichier ou répertoire de ce type
> tar: Statut d'erreur reporté d'erreurs précédentes.

Ok, my french is a little rusty, so I'm guessing the message says I missed 
something with the parameters, maybe their order.

I tried experimenting a bit. I've created tarfiles from pipes a million times, 
but never really extracted to a pipe. 

THEN, I did what we all should have done in the beginning, guess what it's 
that?

You need -O in the extracting command:

tar xfO archive1.tar relative/path/to/file | cat

works to a test text file I used. THEN, when the tar rf comando didn't, I 
remembered you're not adding a file to the tar2, but a stream. So, you don't 
get a filename. Which is why if you try you'll get the error:

tar: Options `-Aru' are incompatible with `-f -'

with a french accent. Sorry.

> I had seen this kind of command but it was for transfering files from
> one tape to another.

That's exactly what you're trying to do, as far as tar is concerned.