Interactivity pre and post install

[Peter Bowen <pzb scyld com>]

RPM currently does not all any user interaction during pre- and
post-install.  This works fine for most people, but the list does get a
number of people asking if they can use read, present information for
the user, etc. in the scripts.  These threads usually end fairly quickly
with a "NO, you can't do that" answer.  However, one thread on the list
from October 30 & 31 that had a good amount of discussion, including a
variety of ideas, including debconf and using python with gtk/newt to
preset the interface.

Using some of the ideas from the thread, I started to work on designing
an extension to RPM that would allow basic interaction with the user
pre- and post-transaction.  I have identified several basic requirements
to make this work.  The first requirement is that the extension be
optional.  This means that the program should not count on the pre/post
transaction input having taken place.  This will allow existing
software, especially automated "robots" to continue to function.  The
second requirement is the interface should be accessible via both text
and GUI mode.  The third requirement is that the script itself should
not present the interface, but rather the requirements for the
interface.   And finally, the fourth requirement is that any scripting
language should be allowed.  Constraining the script to bash, perl,
python, or any one language will leave many users out.

With those basic technical requirements stated, the next, and most
important step is to determine what input developers want from users
when installing packages.  It seems, from my own experience, that the
two main things that people want are license agreement screens for
proprietary software, and post installation configuration screens. 
However, I realize that these are just a small subset of the needs of
the community as a whole, so I ask this question to all:

What user input do you need when you install an RPM?

Seeing as people ask about it every couple of weeks, there should be a
variety of answers to this question, and I would like to address as many
of the needs as possible.

Thanks.
Peter