Re: Problem with tar+gzip/gunzip

[Chris Croughton]

On Thu, 12 May 2005 16:43:15 -0500, Bill Wood 
   <william.wood3@comcast.net> wrote:

> I recently built a tarball by using the command line
>     cd /tmp;tar -zcf home-dir.tgz /home/bill
> and then writing /tmp/home-dir.tgz to CD.
> 
> When I later copied the file from CD to a working dir and attempted to
> unpack it, I got the following result:
> 
>     gunzip -c home-dir.tgz | tar xf -

Hmm, out of interest why didn't you use tar zxf home-dir.tgz?  Was it
the same version of tar for packing and unpacking?  You only mention one
version.

It is possible that the gzip format changed, or that the later version
used something not known by the earlier.

> Was the tar file too large for gzip?  Is there any hope of recovery?

It shouldn't be, the gzip format can handle individual files up to 32
bit size (4GB).

> By the way, I had a slightly smaller tarball made a week earlier that
> generated the same gunzip errors but no tar errors when I tried to
> unpack it.  Is there any hope of recovering it?
> 
> The tar version is 1.14, the gunzip version is 1.2.4, I built the
> tarballs under Mandrake 9.1 and tried to unpack them under Mandriva
> 10.1.

On my Debian woody ('stable') system tar --version gives 1.13.25 and
gunzip --version gives 1.3.2, since you are using a later version of tar
and an earlier version of gunzip I suspect that there is an
incompatibility, the later tar has used a compression format which the
earlier gunzip doesn't fully support.

Try, if you haven't already, doing the uncompression in tar the same way
that you compressed it (using zxf), you can also do ztf to cause tar to
list and check the file without putting the output anywhere (rather
faster than writing them to disk!).

I just tested compressing a 1.5GB directory tree using tar zcf and using
gunzip -c | tar tf - worked fine (with the above versions or tar and
gunzip).

(Incidentally, doing gunzip -l on incomplete files can result in really
weird results!)

Chris C