# boot script for LTS 1804 to unatt LTS 2004
apt-get update 
apt-get -y dist-upgrade | tee -a /root/dis-upgrd.txt
touch /etc/apt/apt.conf.d/local
# while upgrading answer Yes to all for new 
echo 'DPkg::options { "--force-confdef"; "--force-confnew"; }' > /etc/apt/apt.conf.d/local 
time do-release-upgrade -f DistUpgradeViewNonInteractive | tee -a /root/2004LTSupgd.txt 
# echo removing local
echo > /etc/apt/apt.conf.d/local
rm /etc/apt/apt.conf.d/local
# Done now reboot