In this case, a package has been installed. As expected, its scripts are executed. Next, let's upgrade this package:

# rpm -U bother-3.5-1.i386.rpm

This is the bother 3.5 preinstall script

This is the bother 3.5 postinstall script

This is the bother 2.7 preuninstall script

This is the bother 2.7 postuninstall script

#

This is a textbook example of the sequence of events during an upgrade. The new version of the package is installed (as shown by the pre- and postinstall scripts being executed). Finally, the previous version of the package is removed (showing the pre- and postuninstall scripts being executed). There are really no surprises here. It worked just the way it was meant to.

This time, let's use the --noscripts option when the time comes to perform the upgrade:

# rpm -i bother-2.7-1.i386.rpm

This is the bother 2.7 preinstall script

This is the bother 2.7 postinstall script

#

Again, the first package is installed and its scripts are executed. Now let's try the upgrade using the --noscripts option:

# rpm -U --noscripts bother-3.5-1.i386.rpm

This is the bother 2.7 preuninstall script

This is the bother 2.7 postuninstall script

#

The difference here is that the --noscripts option prevented the new package's scripts from executing. The scripts from the package being erased were still executed.