How do I find installed packages that have no install candidate?

Question

I'd like to retrieve a list of installed packages that have no install candidate (e.g., because I removed an apt source file entry). How would I do that on Debian-based systems?

Answer 1

With Aptitude, search for the ?obsolete pattern, possibly with a custom display format.

aptitude -F '%p' search '?obsolete'

Answer 2

This one was updated:

for package in $(dpkg -l | awk '/ii/{print $2}'); do
     if ! grep -xq "Package: $package" /var/lib/apt/lists/*Packages; then
         echo $package
     fi
done

Using apt-cache policy:

for package in $(dpkg -l | awk '/ii/{print $2}'); do
    if ! apt-cache policy $package | grep -q '[0-9] http://'; then
        echo $package
    fi
done