I have been looking for a way to notify KDE users that I’m tinkering with their system. Since I’m usually logged in remotely, knotify doesn’t work, complaining about $DISPLAY not being set. So far, I’ve only been able to find the partial solution below.
KDE has a system service called Write daemon, which can be found in System settings / System administration / Startup and Shutdown / Service manager. It is running by default, and if it is write and wall commands from the command line will be caught and displayed in the Notification area. This is nice, as is the sound this produces by default. However, the pop-up also disappears after about four seconds. It does leave a subtle hint in the taskbar, but this may be easily missed, especially since the users whose systems I tinker with remotely are typically less computer savvy 😉 The behaviour of the notification can be changed (to some extent) in System settings / Common appearance and Behaviour / Applications and System notifications / Manage notifications / Applications tab / Event source: Local system message service.
If you have a better solution, please leave a comment!