#!/bin/bash set -euox pipefail  ## This is only needed for systems with Window Managers  # this is a patch. Firefox seems to have a trick to remove read-only filesystem. We need to unmount that first sudo umount /var/snap/firefox/common/host-hunspell || true  # remov all snaps first as they mount read only filesystem that only snap itself can find and unmount for i in {1..3}; do # we do this three times as packages depends on one another  for snap_pkg in $(snap list | awk 'NR>1 {print $1}'); do sudo snap remove --purge "$snap_pkg"; done done  systemctl --user disable --now snap.firmware-updater.firmware-notifier.timer systemctl --user disable --now snap.snapd-desktop-integration.snapd-desktop-integration.service sudo systemctl disable --now wpa_supplicant.service sudo systemctl disable --now launchpadlib-cache-clean.timer sudo rm /etc/systemd/user/timers.target.wants/launchpadlib-cache-clean.timer # launchpad timer is a heavy beast and must be disabled in global scope sudo systemctl disable --now snapd.snap-repair.timer  ### END Window manager systems   # remove bluetooth if installed from previous GMT installs as it just generates noise and is non standard sudo apt remove --purge bluez bluez-obexd  # Remove all the packages we don't need sudo apt remove -y --purge snapd cloud-guest-utils cloud-init apport apport-symptoms cryptsetup cryptsetup-bin cryptsetup-initramfs curl gdisk lxd-installer mdadm open-iscsi snapd squashfs-tools ssh-import-id wget xauth update-notifier-common python3-update-manager unattended-upgrades needrestart command-not-found cron lxd-agent-loader modemmanager motd-news-config pastebinit packagekit sudo systemctl daemon-reload sudo apt autoremove -y --purge  # Get newest versions of everything sudo apt update  sudo apt install psmisc -y  # on some versions killall might be missing. Please install then sudo killall unattended-upgrade-shutdown  sudo apt upgrade -y  # These are packages that are installed through the update sudo apt remove -y --purge networkd-dispatcher multipath-tools  sudo apt autoremove -y --purge   # Disable services that might do things sudo systemctl disable --now apt-daily-upgrade.timer sudo systemctl disable --now apt-daily.timer sudo systemctl disable --now dpkg-db-backup.timer sudo systemctl disable --now e2scrub_all.timer sudo systemctl disable --now fstrim.timer sudo systemctl disable --now motd-news.timer sudo systemctl disable --now e2scrub_reap.service sudo systemctl disable --now tinyproxy.service # from previous GMT installs sudo systemctl disable --now anacron.timer   # systemd own timers - must be masked as they cannot be disabled sudo systemctl mask --now systemd-tmpfiles-clean.timer systemctl --user mask --now systemd-tmpfiles-clean.timer sudo systemctl mask --now systemd-journal-flush.service  # these following timers might be missing on newer ubuntus sudo systemctl disable --now fwupd-refresh.timer sudo systemctl disable --now logrotate.timer sudo systemctl disable --now ua-timer.timer sudo systemctl disable --now man-db.timer sudo systemctl disable --now sysstat-collect.timer sudo systemctl disable --now sysstat-summary.timer sudo systemctl disable --now systemd-timesyncd.service sudo systemctl disable --now power-profiles-daemon.service sudo systemctl disable --now thermald.service sudo systemctl disable --now anacron.service  # Packages to install for editing. some of us prefer nano, some vim. We install bot to keep wild opinionated mobs away :) sudo apt install -y vim nano  # Setup networking NET_NAME=$(sudo networkctl list "en*" --no-legend | cut -f 4 -d " ") cat <<EOT | sudo tee /etc/systemd/network/en.network [Match] Name=$NET_NAME  [Network] DHCP=ipv4 EOT  # Disable NTP - we trigger it one-off in the cluster service sudo timedatectl set-ntp false  # Disable the kernel watchdogs echo 0 | sudo tee /proc/sys/kernel/soft_watchdog echo 0 | sudo tee /proc/sys/kernel/nmi_watchdog echo 0 | sudo tee /proc/sys/kernel/watchdog echo 0 | sudo tee /proc/sys/kernel/watchdog_thresh  # Removes the large header when logging in sudo rm -f /etc/update-motd.d/*  # Remove all cron files. Cron shouldn't be running anyway but just to be safe sudo rm -fR /etc/cron* sudo rm -fR /var/spool/cron*  # final remove sudo apt autoremove -y --purge  # Desktop systems have NetworkManager. Here we want to disable the periodic check to Host: connectivity-check.ubuntu.com. if [ -f "/etc/NetworkManager/NetworkManager.conf" ]; then  echo "[connectivity]" >> /etc/NetworkManager/NetworkManager.conf  echo "uri=" >> /etc/NetworkManager/NetworkManager.conf  echo "interval=0" >> /etc/NetworkManager/NetworkManager.conf else  echo "NetworkManager configuration file seems not to exist. Probably non desktop system" fi  # List all timers and services to validate we have nothing left  output=$(sudo systemctl --all list-timers) if [[ "$output" == *"0 timers listed"* ]]; then  echo "OK: No system timers listed" elif [[ "$output" == *"- - - - systemd-tmpfiles-clean.timer -"* && "$output" == *"1 timers listed"* ]]; then  echo "OK: Only masked system timers listed" else  echo -e "\e[31mFAIL: Timers are active\e[0m" >&2  sudo systemctl --all list-timers  exit 1 fi  output=$(systemctl --user --all list-timers) if [[ "$output" == *"0 timers listed"* ]]; then  echo "OK: No user timers listed" else  echo -e "\e[31mFAIL: Timers are active\e[0m" >&2  systemctl --user --all list-timers  exit 1 fi  echo "All done. Please reboot system!"