The Update Nag
Ubuntu is configured to aggressively ensure your system is secure. By default, a background service (often update-notifier) silently contacts the Ubuntu repositories every single day to check for new security patches and software updates. When it finds them, it automatically throws a large, persistent pop-up window onto your desktop, demanding you install the updates. If you are managing a stable production server, running a kiosk display, or simply prefer to manually control exactly when your system reaches out to the internet to fetch package lists, this constant background checking and nagging is highly intrusive.
Disabling the Daily Check
To take manual control of your system maintenance and stop Ubuntu from automatically checking for updates in the background, you must adjust the Software & Updates settings.
Open your main application launcher and search for Software & Updates (do not confuse this with the “Software Updater” tool). Open the application. A dialogue box with several tabs will appear. Click on the Updates tab. Look for the dropdown menu labelled Automatically check for updates:. Click this menu and change it from “Daily” (or “Weekly”) to Never. You will likely be prompted to enter your system password to authorize this change. Close the window. From now on, Ubuntu will never scan for updates in the background. You must remember to manually open a terminal and run sudo apt update when you want to fetch new packages.