chain most upgrade tasks with && the same way it is done at DSA

 1. Pre-upgrade backups and preperation:

        sudo apt install ttyrec screen debconf-utils apt-show-versions deborphan

        sudo ttyrec -e screen /var/log/upgrade-buster.ttyrec

        umask 0077

        tar cfz /var/backups/pre-buster-backup.tgz /etc /var/lib/dpkg /var/lib/apt/extended_states /var/lib/aptitude/pkgstates /var/cache/debconf

        dpkg --get-selections "*" > /var/backups/dpkg-selections-pre-buster.txt

        debconf-get-selections > /var/backups/debconf-selections-pre-buster.txt

        apt-mark showhold

        dpkg --audit

        dpkg -l '*dkms' # look for dkms packages and make sure they are relevant, if not, purge.

        sudo apt install ttyrec screen debconf-utils apt-show-versions deborphan &&

        sudo ttyrec -e screen /var/log/upgrade-buster.ttyrec &&

        umask 0077 &&

        tar cfz /var/backups/pre-buster-backup.tgz /etc /var/lib/dpkg /var/lib/apt/extended_states /var/cache/debconf &&

        dpkg --get-selections "*" > /var/backups/dpkg-selections-pre-buster.txt &&

        debconf-get-selections > /var/backups/debconf-selections-pre-buster.txt &&

        apt-mark showhold &&

        dpkg --audit &&

        : look for dkms packages and make sure they are relevant, if not, purge. &&

        dpkg -l '*dkms' &&

        : make sure backups are up to date

 2. Perform any pending upgrade and clear out old pins:

        rm /etc/apt/preferences /etc/apt/preferences.d/* #  Check for pinned (on hold) packages, and possibly disable

        rm /etc/apt/sources.list.d/testing.list # or other similar backports or sources from later releases

        rm /etc/apt/sources.list.d/stretch-backports.list

        apt update && apt -y upgrade

        dpkg -l 'linux-image-*' # list kernel images and purge unused packages

        # look for packages from backports, other suites or archives

        # if possible, switch to official packages by disabling

        # third-party repositories

        : Check for pinned (on hold) packages, and possibly disable &&

        rm -f /etc/apt/preferences /etc/apt/preferences.d/* &&

        rm -f /etc/apt/sources.list.d/testing.list &&

        rm -f /etc/apt/sources.list.d/stretch-backports.list &&

        apt update && apt -y upgrade &&

        : list kernel images and purge unused packages &&

        dpkg -l 'linux-image-*' &&

        : look for packages from backports, other suites or archives &&

        : if possible, switch to official packages by disabling third-party repositories &&

        apt-show-versions | grep -v /stretch | grep -v 'not installed$'

 3. Check free space, see [this guide to free up space][] and

    download packages:

        sed -i 's/stretch/buster/g' /etc/apt/sources.list.d/* /etc/apt/sources.list

        apt update; apt -o APT::Get::Trivial-Only=true dist-upgrade; df -h

        sed -i 's/stretch/buster/g' /etc/apt/sources.list.d/* /etc/apt/sources.list &&

        apt update && apt -o APT::Get::Trivial-Only=true dist-upgrade && df -h &&

        apt -y -d upgrade && apt -y -d dist-upgrade

 4. Actual upgrade run: