Upgrading Ubuntu 16 (Xenial)

upgradebionic18.sh

#Make enough swap space if you have less than 2Gb memory

sudo swapoff -a

sudo fallocate -l 6G /swapfile

sudo chmod 0600 /swapfile

sudo mkswap /swapfile

sudo swapon /swapfile

sudo apt-get update && sudo apt-get upgrade

#if you run into any issues with out of date pkeys run the command below to update

#run sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv KEY_TO_REFRESH
#it is very important you ensure there are no pgp key errors before upgrading, remove any apt source list that is unsupported/deprecated
#before upgrading

sudo apt-get dist-upgrade

#you should likely be ready to upgrade at this stage

#update ciphers if needed to ensure you're able to login after upgrade..
sudo sed -i 's/^Ciphers .*/Ciphers +aes256-cbc,aes192-cbc,aes128-cbc/' /etc/ssh/sshd_config

sudo do-release-upgrade