• Based on this Discussion
• Tested with Ubuntu 20.04 (Gnome, XFCE and KDE)
• Use Cases:
  • You want to notify Desktop users after some package installation
  • You want to notify Desktop users after doing some sysadmin tasks with Ansible or similar

Requirement

Usually comes pre-installed with Gnome and XFCE.
For KDE I had to manually install it.

apt install update-notifier-common

Files

All Desktops poll the directory /var/lib/update-notifier/user.d/ for changes.
KDE in shorter intervals than Gnome and XFCE.
It can take up to 5 minutes until the next poll comes around and the message gets displayed.

Gnome and XFCE display only new or changed messages since the last display.
KDE shows old messages again if they are still lying around.
So with KDE, make sure to remove old stuff in this folder
before putting new messages in it, so users don't get confused with old messages.

Examples

/var/lib/update-notifier/user.d/a-message

Name: A Message
Description: Hello Desktop

/var/lib/update-notifier/user.d/another-message

Name: Another Message
Description: Hello Desktop again

Gnome

A Message

Another Message

Both Messages

Note the Next Button

XFCE

A Message

Both Messages

Note the Next Button

KDE

A Message

Both Messages

• It starts small
• It needs detailed care in the beginning
• The Logs get bigger after every step (pun intended)
• After booting up, it runs kind of by itself
• If you do it wrong you can get burned or all is one fire

Es gibt tolle Videos auf YouTube wie man mit einer Axt effektiv Feuerholz macht:

Doch der Pragmatiker hat noch einen effektiveren Trick auf Lager.
Er kombiniert es mit dem Sport und fräst beim Disc Goalfen gleich das Holz zu:

Nur Stahl kann ihn noch aufhalten (noch):