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Re: Bug#164889: md5sum <FILE produces spurious ` -' in output



>>"Raul" == Raul Miller <moth@debian.org> writes:

 Raul> On Mon, Nov 11, 2002 at 03:31:51PM +1000, Anthony Towns wrote:
 >> debootstrap broke. Things of the form:
 >> x=`cat foo.changes | grep blah.*deb | cut -d\  -f2`
 >> y=`md5sum < blah*.deb`
 >> if [ "$x" != "$y" ]; then

 Raul> Hmm...

 Raul> There are essentially two approaches to this class of problem.

 Raul> [1] require that md5sum not break this kind of code.
 Raul> [2] require that this code be modified to work with the "new" md5sum.

	Then we need a transition plan. 

 Raul> If we're going to go with [2], we can require a change of the form:

 Raul> 	y=`md5sum < blah*.deb | awk '{print $1}'`


	Fails for md5sum /some/file >> hash-file-to-be-parsed-later

 Raul> Since making this kind of change doesn't break use of the
 Raul> existing md5sum, I think we should recommend that all apps
 Raul> using md5sum test using the gnu variant and be modified so they
 Raul> work with either version.  In particular, we should allow bugs
 Raul> to be filed against packages which don't support the gnu
 Raul> version.

	wishlist bugs?

 Raul> Until all those bugs have been closed -- and until every package with
 Raul> a md5sum dependency has had a chance to be tested -- we should forbid
 Raul> deployment of the gnu version.

	How do we keep track of these bugs? 

 Raul> Also, taking a step back:

 Raul> Once we're done with this specific issue, maybe we should think about
 Raul> making this kind of phase-in process an option for package developers
 Raul> to introduce on their own.  In other words, allow people to say:

 Raul> a I'm going to change XXX in a way that breaks the existing interface.

 Raul> b You have a package with a dependency on my packages which
 Raul> contains XXX. 

 Raul> c Here's one way to write code that will work with either interface.

 Raul> d Here's where to get an instance of the new interface for you to test
 Raul>   against.

 Raul> e [stuff about bug filing/closing and the eventual release of the new
 interface> 

 Raul> Comments?  Opinions?

	This requires way more thought than this. Proper dependency
 handling isa complicated; and a generic, scalable solution takes eons
 to hammer out. 

 Raul> One thing that bothers me about these kind of migrations is that older
 Raul> packages aren't going to know about interface changes introduced in
 Raul> newer packages.  This almost requires a [potentially large and ugly]
 Raul> versioned "Conflicts:" in the package which supplies the new interface.

	Also: We need to worry about upgrades. We used to worry about
 partial upgrades -- people running mostly stable but upgrading a few
 packages from testing.


	These conficts against versions of packages that depend on on
 one could get impossible to collate; unless tools are provided that
 can walk all the dependency relationships and provide one with a
 current list (keeping in mind that some of these packages may also
 provde a versioned dependency on the package whose interface is
 changing). 

	I think this is going to be impractical unless for the very
 seldom used packages. 

	Ideally, the packages should provide a virtual package with an
 interface version embedded in them (md-interface-1.1), and packages
 depend on that interface; but even that fails to scale for packages
 that may provide multiple interfaces, only some of which are
 changing.

	manoj
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Manoj Srivastava   <srivasta@debian.org>  <http://www.debian.org/%7Esrivasta/>
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