Use tar to append?

[Cameron Simpson]

On 09Mar2007 17:51, Les Mikesell <lesmikesell at gmail.com> wrote:
| Cameron Simpson wrote:
| >I have also thought of a much simpler way to solve your problem.
| >The trailer record is the source of all our pain. Write a small perl or
| >python or C program that seeks to the end of stdout minus the length of
| >the trailer record then execs a "tar cf - ..." for you. Thus:
| 
| It's been ages since I looked at the tar source but I could have sworn 
| it tried to do that itself if it could seek on the media.

Well it _should_ in append/update mode, but Mike McCarty's tests seem to
show that GNU tar is doing something obscenely expensive in these modes,
not merely backing over the trailer and appending. I imagine it's doing
some table of contents rationalisation or such. I would have imagined
that the --concatenate ("A") mode would just backspace over the trailer
and append, but it seems not.

hence the hack.
-- 
Cameron Simpson <cs at zip.com.au> DoD#743
http://www.cskk.ezoshosting.com/cs/

You try and make the place as secure as you can, but you don't reckon
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