question about TAR

[Ouattara Oumar Aziz (alias wattazoum)]

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Owen Townend a écrit :
> On Thu, 2007-11-29 at 23:14 +0100, Ouattara Oumar Aziz (alias wattazoum)
> wrote:
> 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 ?
> 
> Best regards
> wattazoum
>>
>>

> Hey,
>   Tar can add to an existing archive (--append or --concatenate), so the
> second part's OK. Tar can extract parts of and archive (--extract) and
> tar can remove parts of an archive (--delete) but I am not sure there is
> a way to use all of these simultaneously to facilitate a move. Some disk
> space will need to be used.
>   Depending on the file sizes you may be able to use the available space
> and do the move in many small steps instead of one large one. Another
> option could be to extract the files to an external storage medium,
> remove them from the previous archive before then re-reading them into
> the new archive.
>   Do you have other IO available if there's no disk space? A spare tape
> or networked machine?

>   Just some thoughts.

> cheers,
> Owen.

Thank you very much for your answer. I think I'll do it using the disk (
extracting and reTarring it back ) one file at a time.

This is for a backup software that I am developing that's why I needed
to have a generic way to do it (without assuming that the user have some
free hardrive ) :-)

Thanks again
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