Re: [Bug-tar] Possible tar bug

[Paul Eggert]

On 12/26/2010 11:40 AM, address@hidden wrote:
> The -r option is extactly what I want since with it the tar appends to end of 
> archive.

OK, but you're wearing out the tape drive unnecessarily, since it
reads the whole tape.  It'd be much faster to seek to the end of
the file on the tape, go back two blocks (for tar's EOF marker),
and then start tar from there.  And it'd be even faster simply
to append a new tar image to the tape, so that the tape contains
multiple files.

Anyway, I suspect your tape got polluted with a ustar-format
archive; perhaps you used another version of tar, or tar with
some unusual options, to create it in the first place; or maybe
it just had some leftover data on it that happened to look like
a ustar-format archive.  To avoid this problem in the future,
please make sure you use 'tar -c' the first time you write to
the tape, and use 'tar -r' only after the tape is safely initialized.