When packaging systems go awry (Was: Re: Are we losing users to Gentoo?)
On Wed, Nov 20, 2002 at 04:59:04PM -0500, Joey Hess wrote:
> Glenn McGrath wrote:
> > I didnt realise that, what are its bad points... i guess it could make
> > dependencies a bit tricker.
>
> The way redhat does it means you have to distinguish between installing
> packages and upgrading them. If you install a newer version of something
> without expliticly telling it to upgrade it, you end up with two
> versions installed.
[snip]
Ick. If I had to choose, I'd stay away from rpm for this one reason alone.
Experience shows that installing the same package more than once, esp.
with different versions, gets you into an absolute, total mess.
Theoretically, it should be OK, but in practice, there are just too many
assumptions made by software, hardcoded paths, etc., that just do NOT
allow it to live with another version of itself nicely. (Except if they
reside in different chroot jails.) Not to mention bad interaction with
other packages (package X requires package Y -- but which *version* of
package Y if more than one are installed?)
Once you get into this state, you start having to solve issues like not
removing a file until both packages that ship the same file are removed,
replacing an old file with a newer one, hoping that whatever old stuff
depends on it will work with the new version (cf. MS windows, the feared
prompt "This driver is about to overwrite an older version of file
AAA.BBB, proceed?"), or the packaging system just totally getting confused
and screwing up everything whenever you try to do anything with the
multiply-installed package(s) (eg. Solaris, where the only way to restore
sanity is to completely remove all copies of the package and then
reinstall exactly one copy).
In short, you get into a quagmire of spiderweb-fragile implicit
dependencies, install-order dependencies, and all sorts of other
horrendous stuff that is practically impossible to wrap your brain around.
Yuck. Been there, done that, don't ever wanna go near it again.
T
--
People walk. Computers run.
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