Though I use only the command line to do system updates, I still got system restart messages every time a new kernel version was installed. While they can be helpful, I actually prefer to be left to my own devices when it comes to restarting a system and I may have a something running at the time that I do not wish to interrupt.
In Ubuntu GNOME 13.10 and before, there was no sign of these messages so I decided to see if I could go nag free again. The responsible application is called Update Notifier and I tried seeing if I could remove it but that act has a major impact of the system so it was not a useful way to go.
As it happens, it is an application that starts up automatically at computer boot time but there was no sign of an entry for it in the Startup Applications Preferences screen (started using from the command line using gnome-session-properties). The for this is that there is flag called NoDisplay in the relevant autostart shortcut in /etc/xdg/autostart/ that stops it appearing in the aforementioned settings screen when set to true. The trick then is to set it to false and the following command (broken over two lines for sake of display and quotes could need replacing when you issue the command too) does the trick for all such hidden start-up applications:
sudo sed -i ‘s/NoDisplay=true/NoDisplay=false/g’
What the above does is that sed goes into every file and changes NoDisplay=true to NoDisplay=false in each file with the desktop extension. When that has completed, there are more entries in Startup Applications Preferences and Update Notifier can be deselected in order to stop it starting. Removing the relevant .desktop file would be a more permanent change but this one will do me, especially since no more of those pesky restart messages appear anymore. My regularity when it came to system updates meant that the update messages never appeared anyway and I tend to shut down my system at the end of every day so the updates will be picked up too so all should be well.