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Re: FWD: Debian's Perl installation

On Sat, Feb 28, 2004 at 11:47:02AM -0500, kynn@panix.com wrote:
>On Tue, 24 Feb 2004 18:36:51 +1100 Brendan O'Dea wrote:
>>In short, if you want a non-standard perl (version, ABI, whatever)
>>install to /usr/local.
>Are you saying that there is *no* way to use apt-get/dpkg whenever the
>user wants to use different configuration options from the ones in the
>Debian distribution?  This is nuts!  I can see how some configuration
>options (e.g. install directories) would be hopelessly incompatible
>with apt-get/dpkg, but configuration options such as -Dusethreads???
>Why should that be fundamentally incompatible with apt-get/dpkg???

A distribution is not just a random bunch of packages, it is a bunch of
packages which are tied together by dependencies.

If you replace perl with a binary using a different ABI you break those
dependencies--i.e.  if you rebuild the perl packages w/- -Dusethreads
then any binary (XS) modules compiled with the "normal" package will
break at run-time, even though dpkg considers them installable since the
dependencies are met.

As an exaggerated example, if you were to replace the libc6 package with
something which either did not include /lib/libc.so.6, or did so with a
library which didn't provide printf or was 64bit (on a 32bit platform)
then your system would break spectacularly--even if all the "broken"
packages were considered installable by dpkg.

So the issue is not directly with apt/dpkg, since any package rebuilt
with binary-incompatible options may well be installed without problems
with those tools--you just need ensure that you *also* re-build all
dependent packages as well.

Packaging is a mixed blessing.  After maintaining proprietary Unix
systems for years (generally with a larger /usr/local than /usr) I felt
liberated when I discovered [slackware] Linux and had the ability to
overwrite /usr with impunity.  Such joy was short-lived however, since I
before long had to maintain several such machines.  In the end I looked
for an alternate distribution and ended up with Debian--and any local
changes back in /usr/local :)

> Tue, Feb 17, 2004 at 10:49:58PM -0500, Joey Hess wrote:
>>>----- Forwarded message from kynn@panix.com -----                       
[I wrote]
>>I'm guessing that he built perl from the Debian source packages after
>>removing -Dusethreads from debian/config.debian, but didn't have all the
>>build-depends installed (libgdbm-dev specifically).
>If you could elaborate on this, I'd appreciate it.  How can one find
>out what are the build-depends?  Would it be enough to install these
>to get the (modified) Perl installation to go?

 $ man apt-get


 # apt-get build-dep perl


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