apt being notified when a package version is available

One simple way would be to run:

apt-get -s --only-upgrade install package1 package2 ... 

You could put that in a script that builds the package list from a file, runs apt-get update and then the command above.

So, I ended up with the thing below for now, it seems to work, would have been nice if -u supported more packages, watching many may become slow.

/etc/apt/watch a text file with one package name for line (# comments supported)

/usr/local/bin/apt-watch.sh:

#!/bin/sh test -f /etc/apt/watch || exit 0 apt-show-versions -u $(grep -v ^# /etc/apt/watch) >/tmp/apt.watch if [ $(cat /tmp/apt.watch | wc -l) -gt 0 ] ; then cat /tmp/apt.watch | mail root -s '[apt watch] upgrades available' fi 

/etc/apt/apt.conf.d/99-apt-watch:

# check upgrades avaiable for watched packages APT::Update::Post-Invoke { "[ ! -x /usr/local/bin/apt-watch.sh ] || /usr/local/bin/apt-watch.sh || true"; };