Jeff Johnson wrote:
On Sep 15, 2008, at 11:24 PM, Michael A. Peters wrote:
Toralf Lund wrote:
I've run into an installation order issue related to the "post"
scriptlet in one of my packages. Basically, this scripts executes a
(command-line only) program installed by the package, and this
program pretty much needs everything required by the package. The
problem is, if I install my package along with some of the required
software, the requirements are often installed *after* the "main"
package [ ... ]
Perhaps my understanding is wrong - but I believe:
Um, yes, wrong.
[ .. ]
The %pre and %post scripts are run immediately before/after a package
is installed,
not after all the packages are installed.
Exactly. This is what's causing me trouble; essentially, I have a
command that would be better to run at the end of the entire
transaction. But I think I understand why rpm doesn't work that way...
This is also true for %preun/%postun when a package is erased, the
scripts are run
immediately before/after the erasure.
My understanding of this may not be 100%
What is most confusing is that rpm does install before erase. Which
means that %post
scriptlet is run before %preun is run, which is perhaps
counter-intuitive, but is exactly
what is needed if shared libraries are being upgraded on live systems.
The new librrary
must be installed before the old library is removed in ordeer to
minimize the window
where the library is not available.
Quite.
[ ... ]
And finally that brings the topic to context markers like
Requires(post) etc.
Context markers like Requires(post) are intended to break dependency
loops while
ordering.
A package that "needs" some other package solely while running a %post
scriptlet,
not after being installed, can carry a Requires(post) hint to the
ordering within rpm.
In my case the script and the package itself both need (more or less)
the same libs. Logically, they may be seen as independent sets of
dependencies, though, I think...
The hint excludes dependency loops between install <=> erase packages.
The other major affect of adding an explicit Requires(post) hint is
that those
dependencies are not registered in an rpmdb because they were needed
solely
for installing, not for using or erasing, a package. There's no need
to keep track
of the install context dependencies after the install has been done
because
the %post scriptlet is run only during install, never run after install.
hth
Well. It doesn't help me too much with my original issue. But, like I
said elsewhere, I can't seem to reproduce the problem I thought I had,
so maybe it doesn't matter. I'm still confused, though.
Question: Can I generally assume the packages are ordered according to
"Requires" these days, i.e. that if package A requires something
provided by package B, then B is installed before A (when A and B are
both part of the same transaction)? I'm fairly sure I couldn't when I
started using rpm, so I had to mess about with ""PreReq" instead...
73 de jeff
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