Re: [Bug-tar] Possible tar bug

[Joerg Schilling]

Paul Eggert <address@hidden> wrote:

> Well, I have to admit, I'm at a loss as to why you're
> experiencing the bug.  Perhaps if you run 'tar' under
> GDB you can see why it thinks the tar file is ustar format
> rather than GNU format.  I expect that it's some unanticipated
> confusion between -r (which needs to guess the tar format from
> the existing tape) and -M (which allows for multiple tapes,
> some of which may be of different formats!).

It seems that one of the most important resons for such problems is the fact 
that GNU tar does not check for the archive format in existing archives.

Other tar implementations do at least warn in case that someone tries to append 
in a different archive format.

The other problem seems to be the usage. The option -r is rather unusual in 
real life and in special regarding to backups. A clean way to make backups is to
append integral incremental dumps after a new filemark on the tape.

Jörg

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