Remove Updated Software Notification on 20.04.2 LTS
Solution 1:
Warning: the below answer disables update popups, this may end with lower security level for your system. Continue only if you are sure.
To disable update-notifier popup on Ubuntu 20.04 LTS use the following commands:
# disable cron jobs for Update Notifier
sudo chmod -x /etc/cron.daily/update-notifier-common
sudo chmod -x /etc/cron.weekly/update-notifier-common
# disable graphical Update Notifier application
mkdir -p ~/.config/autostart/
cp /etc/xdg/autostart/update-notifier.desktop ~/.config/autostart/
grep -q "^X-$XDG_CURRENT_DESKTOP-Autostart-enabled" ~/.config/autostart/update-notifier.desktop && sed -i "s/X-$XDG_CURRENT_DESKTOP-Autostart-enabled=true/X-$XDG_CURRENT_DESKTOP-Autostart-enabled=false/" ~/.config/autostart/update-notifier.desktop || echo "X-$XDG_CURRENT_DESKTOP-Autostart-enabled=false" >> ~/.config/autostart/update-notifier.desktop
and then reboot.
To disable update-notifier popup on Ubuntu 21.04 use the following commands:
# disable cron jobs for Update Notifier
sudo systemctl disable update-notifier-download.timer
sudo systemctl disable update-notifier-motd.timer
# disable graphical Update Notifier application
mkdir -p ~/.config/autostart/
cp /etc/xdg/autostart/update-notifier.desktop ~/.config/autostart/
grep -q "^X-$XDG_CURRENT_DESKTOP-Autostart-enabled" ~/.config/autostart/update-notifier.desktop && sed -i "s/X-$XDG_CURRENT_DESKTOP-Autostart-enabled=true/X-$XDG_CURRENT_DESKTOP-Autostart-enabled=false/" ~/.config/autostart/update-notifier.desktop || echo "X-$XDG_CURRENT_DESKTOP-Autostart-enabled=false" >> ~/.config/autostart/update-notifier.desktop
and then reboot.