How to tell aptitude to automatically install missing packages instead of removing ones to statisfy dependencies?

Question

I'm creating a live CD with Skype using live-build. During the build process I run the following script:

# Download the Skype package suitable for Squeeze
wget --continue -O skype-install.deb \
    http://download.skype.com/linux/skype-debian_4.0.0.7-1_i386.deb
# Install the package.
dpkg -i --force-architecture --no-debsig skype-install.deb || true
# Fix missing dependencies
aptitude -f install

The problem is that aptitude -f install suggest to remove Skype instead of installing the missing libraries. I have to tell it interactively to prefer the second solution. Can I tell somehow on the command line? Ideally I'd like to run it unattended like

aptitude -y --some-flag-to-ensure-no-removals -f install

Answer 1

It might be possible to use aptitude's --safe-resolver option to do what you want. Quoting the man page for aptitude 0.6.8.2:

This resolver attempts to preserve as many of your choices as possible; it will never remove a package or install a version of a package other than the package's default candidate version.

To do it globally, set Aptitude::Always-Use-Safe-Resolver to true.