[Yum] RE: yum compatibility backward with rpm

seth vidal skvidal at linux.duke.edu
Mon Jul 30 22:43:46 UTC 2007


On Mon, 2007-07-30 at 15:40 -0700, Skahan, Vince wrote:
> To answer Jim and Seth's responses, the reason I think a very-optional
> set of "--force" and/or "--nodeps" options would be helpful is that it
> would help me use the very nice yum feature set to make custom smaller
> rpm-based distros without needing to hack on the vanilla Fedora rpms
> themselves at all.   There are a variety of 'requires' and other
> configuration things defined in the rpms in vanilla Fedora that do not
> make equal sense for the embedded-like distro I'm trying to cook up from
> a drastic subset of the rpms Fedora supplies.
> 
> Examples - our lawyers want a custom /etc/issue but RH/FC historically
> had that file set as unalterable in the rpm it was provided with, so me
> trying to alter the login banner with a rpm caused a rpm dependency
> conflict of multiple rpms claiming the same file.   Also, all RH-based
> distros really want a MTA present, I absolutely don't.   Many rpms have
> cross-dependencies to things like gnu readline or other interactive
> packages.  In an embedded os nobody needs those goodnesses.
> 

This is why you rebuild those packages, removing the dependencies and
the linkages you don't need. 

However, given what you've described I'm curious how small, small is for
you. I've gotten a fedora6/centos5 box down to 97pkgs - roughly a 350MB
install. That's pretty trim. That included rpm, python and yum plus the
networking tools.  I'm pretty sure there was no mta on there. and I did
all of that w/i correctly closed dependencies.

> Example 2 - yes, I know how to build bogus rpms that 'claim' to 'provide
> xyz' so that dependency checks can be met via sleight of hand.  I'm
> somehow less sure how to supersede a bad rpm itself (the /etc/issue
> example above) without nuking something manually in a postinstall script
> or by manual commands in a wrapper installation script.  I'd really like
> to be able to set up a custom repo and do a rpm install from there, and
> have the rpms do it all.

Again, this is just rebuilding the fedora-release pkg. It takes less
than a few minutes to do. 

> Lastly, I have to take exception in the use of the words "incredibly
> stupid" and "fathom any sane reason why" in a couple of the responses.
> The fact that I see places where yum could be 'more' useful if it was
> more rpm-like is neither stupid nor insane by any definition of the
> term.  Sometimes having a bigger swiss-army-knife even if most folks
> never use that last two tools is goodness to the folks who 'would' use
> that kind of feature set.

The problem about what you want on your swiss army knife is that it ends
up meaning that someone who doesn't know any better eats their system
with --force and --nodeps and this is OUTRAGED that we can't help them
unscrew it.

I don't enjoy bug reports where a look at their rpmdb explains that
there's no way they could have gotten from here to there working within
the bounds of how the program is supposed to work.

--nodeps and --force are options that end up making people who don't
know any better damage their systems. I've cleaned up enough systems
like that to not be a party to causing more of them.

-sv







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