[CentOS] rpm -U query

Fri Apr 23 09:13:54 UTC 2010
James Hogarth <james.hogarth at gmail.com>

On 22 April 2010 22:18, Steve Thompson <smt at vgersoft.com> wrote:
> CentOS, RHEL, all versions.
> Suppose I am upgrading a package foo-1.0 to foo-2.0 (assume foo is not
> relocatable), and both packages have %preun sections in their .spec files.
> It appears that foo-1.0's %preun is run after foo-2.0 has been installed.
> So what happens if foo-1.0 needs to run a binary that was provided as part
> of foo-1.0 during its %preun stage, and a binary of the same name is
> provided with foo-2.0? The installed binary is now foo-2.0's, right? So
> how to run foo-1.0's binaries during its %preun stage? Is the old binary
> available under a different name before it gets erased?
> -steve
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the order in an upgrade is...

new %pre
new %install
new %post
old %preun
old %files removed
old %postun

Check the rpm spec documentation online for the specific details but
the four % scripts have a single argument supplied to them which you
can test. It is a numerical value equivalent to the number of times a
package appears in the RPM database after the package is
installed/erased at that point.

So on a fresh install....

%pre $1 = 1
%post $1 = 1
%preun and %postun unused

On an upgrade...

%pre $1 = 2
%post $1 = 2
%preun $1 = 1
%postun $1 = 1

On a remove....

%pre and %post not used
%preun $1 = 0
%postun $1 = 0

If you have an old package without tests and you are concerned that
the scripts will conflict with each other you can always do...

rpm -e --nodeps <pacakage>
rpm -i <package

That will remove and install in an order you might prefer for the
scripts until they are fixed...

See: http://www.rpm.org/max-rpm/s1-rpm-inside-scripts.html