The upgrade asks many times questions like these:
Configuration file `/etc/squirrelmail/apache.conf'
==> Modified (by you or by a script) since installation.
==> Package distributor has shipped an updated version.
What would you like to do about it ? Your options are:
Y or I : install the package maintainer's version
N or O : keep your currently-installed version
D : show the differences between the versions
Z : background this process to examine the situation
It makes upgrade process to require quite a much work, because of
the manual method the conflicts are resolved:
Type D to see what's changed
Type Z to shell out and manually do all the work, launch
the editor, load the files, compare, diff, merge, reject
The situation could be helped if APT offered a new selection:
M : run Merge program
Where the program and it's arguments could be defined in /etc/apt.conf.
There could be comment in /etc/apt.conf how to launch emacs to handle
changes with ediff.el etc.
emacs --no-windows --no-init-file --no-site-file \
--load ediff \
--execute "(ediff \"%FILE%\" \"%FILE%.dpkg-dist")"
Where %FILE% were the name of the configuration file which APT would
substitute when using the defined call program.
Jari