get a list of all packages installed which are no longer available from the current sources

outdated_packages.py

#!/usr/bin/python
#
#     Generates and prints list of packages that are no longer available on the system from existing apt sources.
#     
#     * Ensure your package lists is up-to-date - run apt-get update
#
#     Author: Aron Podrigal <[email protected]>
#

import os, sys


installed = os.popen("dpkg -l |awk '/^i/ {print $2,$3}'").read().split('\n')
num_pkgs = len(installed)
num_processed = 1

need_remove = []

for p in installed:
    package = p.split(' ')
    if len(package) != 2:
        continue
    name, version = package
    
    sys.stdout.write('\rproccesing %.2f%%: %d/%d packages --  %50s' % (100.0 / num_pkgs * num_processed, num_processed, num_pkgs, name))
    sys.stdout.flush()
    num_processed = num_processed + 1
    apt_cache=os.popen("apt-cache madison %s |awk '{print $3}' |uniq" % name).read().split('\n')
    if version not in apt_cache:
        need_remove.append((name, version))

pkglist = ' '.join([n[0] for n in need_remove])
sys.stdout.write('+Done. to install thos packages from your existing stable repo do  ` apt-get -t <source> install\n')
sys.stdout.flush()
print pkglist