¿Como enviar un mensaje al terminar de instalar un paquete?

En la %post

http://docs.fedoraproject.org/en-US/Fedora_Draft_Documentation/0.1/html/RPM_Guide/ch09s04s05.html

Lo que no se es como tirar un mensaje, quizá puedes ejecutar zenity o algo similar

saludos

Que lo que quieres es algo así:

Sometimes it is necessary to warn the user about some particular care that should be taken when upgrading or installing a specific version of a package.

The following file name formats can be used:

• README.install.urpmi: displayed when the package is initially installed
• README.version.upgrade.urpmi and README.version.update.urpmi: displayed when the package is updated to version version or above, from a version that is less than version (version should be either a package version, epoch:version, version-release, or epoch:version-release, the shorter the better)

Also supported are README.urpmi (displayed in all cases) and README.upgrade.urpmi/README.update.urpmi (always displayed when upgrading). These shouldn't be used as they cause the message to be shown in every subsequent update, even if the user has already seen the message many times.

HOW TO DO (example with README.install.urpmi):

• put a README.install.urpmi in the SOURCES/ directory
• add it in the spec as SourceX: README.install.urpmi (replace X with an appropriate number)
• in %install section : install -m644 %{SOURCEX} README.install.urpmi (notice the absence of %buildroot prefix here)
• in %files section, add README.install.urpmi in a %doc macro, or add a %doc macro if there is none