yum update problem

[James Wilkinson]

Timothy Murphy wrote:
> My idea was that I could just "yum remove" and then "yum install"
> to get back to the original position,
> but I found that these operations are by no means mutually inverse,
> as "yum remove" seemed to remove a whole range of packages
> which for some reason I was not able to recover with "yum install".
> Maybe "yum remove" should come with a health warning?

Um. If package A works perfectly well as a program on its own, but
packages B, C, and D depend on it (so you can either have just A
installed, or A and some combination of B, C, and D), and you run
yum remove A
then B, C, and D will also have to be removed because they depend on it,
and will no longer work. If you then do
yum install A
then yum won't know that you also want B, C, and D, because they aren't
needed.

Or, to put it mathematically,

yum remove A removes the set of packages that are *dependent on* A
(including A)
yum install A installs the set of packages that A *depends on*
(including A).

"Depends on" is not symmetric, so "depends on" is not an equivalence
relationship, and you don't get equivalence classes.

But you can recover them by looking in /var/log/yum.conf, and seeing
what was removed. Then use yum to reinstall them.

Hope this helps,

James.

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