About md5sums of debian sources

[Giorgio Pioda <gfwp@ticino.com>]

Hi Damyan and mentors,

just a very stupid question (sorry!) about tarball formats:

About building a debian package using uupdate (where the former source
was in tar.gz and the update in tar.bz2) I got the comment that the
md5sum of the original upstream source and of the debian source were
different (uupdate recompress the upstream).

I argued in my previous message that this fact is automatic:


>> P.S. the md5sum of orig.tar.gz and peless.tar.bz2 are obviously not
>> the same, but uupdate repackages it automatically during upgrade. If
>> this is an issue, the I'll upload a version created from scratch
>> using only peless-1.125.tar.bz2.

Damyan, you answered the following:

> What you should do in this case is to re-compress the tarfile with
> something like "bzcat some.tar.bz2 | gzip -9 > some.tar.gz". This way
> the tar itself will remain exactly the same. In any case, no need to
> create anything from scratch!

What I don't understand is the need of such an operation;

If I try to recompress peless-1.125.tar.bz2 to peless-1.125.tar.gz (as
suggested above) the md5sum changes, and doesn't correspond to md5sum of
the peless_1.125.orig.tar.gz generated by uupdate. I actually get 3
different md5sums!

Is it really possible to change the compression format .bz2 to .gz and
keep the exact md5sum? My ignorance is big.... If yes, I don't know how
(as the command proposed above is not effective, even testing all the
possible gzip options from -1 to -9. If no, what is the sense of this
work, since there will be anyway the dought that I've modified the
upstream source?

What I would find intelligent would be a peless_1.125.orig.tar.bz2
instead of a peless_1.125.orig.tar.gz (just filename modification) so
the md5sum will naturally match... Is it possible to use .orig.tar.bz2
in debian sources???

cheers

Giorgio