Revert all packages from non-PPA versions to their latest PPA version.

revert_packages_to_ppa_versions.sh

#!/usr/bin/env bash

# BSD 3-clause license, copyright Martin Pecka @ 2019

# This script outputs a command that will revert all packages from non-PPA versions to their latest PPA version.
# This may be handy i.e. for finding packages for which you installed a newer version from a .deb file, or after
# incompletely removing a PPA.

export LC_ALL=C

command=""

for p in `dpkg-query --showformat='${Package} ' -W`; do
    if [[ $(apt-cache policy $p | grep -Pzo "\*\*\* [^\n]+\s+100") ]]; then
        versions=$(apt-cache policy $p | tr "\n" "\r" | grep -Po '(?<=\r )[ *]{3} [^\r]+ [0-9]+\r\s+[0-9]+' | sed 's/ [0-9]\+\r\s\+\([0-9]\+\)/ \1/g' | tr "\r" "\n")
        installable_versions=$(echo "${versions}" | grep -v " 100$")
        version_to_install=$(echo "${installable_versions}" | head -n1 | grep -Po "\s+\K.*(?= [0-9]+$)")
        if [[ ! -z "${version_to_install}" ]]; then
            echo "${p}=${version_to_install}"
            command="${command} ${p}=${version_to_install}"
        else
            echo "${p}: no PPA version"
        fi
    fi;
done

echo "To revert packages to their latest PPA version, call the following command as root. Please, carefully go through the list of changes apt-get will present to you!"
echo "apt-get install ${command}"