Use tar to append?

[Cameron Simpson]

On 08Mar2007 23:06, Mike McCarty <Mike.McCarty at sbcglobal.net> wrote:
| Cameron Simpson wrote:
| >Tar files have a terminating record. To append you need to overwrite
| >that record, and that you can't do in compressed state.
| 
| Fine. How do I get tar actually to append? I can compress later, if
| need be, I guess.

Maybe:

  tar Af tarfile more-files...

Seems like it should do the trick. It should be efficient if the tarfile is
not compressed. But I'm saying this on the basis of the info file for
GNU tar, and I'm presuming that "A" is more efficient than "r", though
the info file is... vague... about this (to be charitable).

You will have to compress later. And to allow doing more appends
you may want to keep the original around:

  gzip -9 < your-big-tarfile >tgz-for-k3b.tgz
  k3b the tgz file ...

or I suppose:

  gunzip big-tarfile.gz
  tar Af big-tarfile more-files...
  gzip -9 big-tarfile.gz
  k3b big-tarfile.gz ...

Depends on your storage facilities I would guess.

| >But I must be missing something. Why append to the tar file at all?
| >Why not just make a lot of separate tar files?
| 
| Because I'm using CDROMs with K3b to write them, and I want as
| much on a single disc as possible, without a lot of fiddling
| to find which ones will fit with minimal wasted space. If I
| use a single file, and split it, I get no wasted space at all
| (except on the last disc, which is unavoidable).

Ok, that makes sense.

| Ok, I'm asking about means rather than goals. Let me restate
| my desires.

I often find it useful to ask about goals when the means seem to be
causing trouble.

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

I always thought that if you have too many errors that the compiler catches,
the compiler should aid your program development by deleting the source.
        - meissner at osf.org