Garuda doesn't install this for KDE Plasma since
write are really aimed at multi-user systems.
But, I like to use wall to notify myself about what my backup scripts are up to. Since they are started as an anacron job, I can't use the notification system (separate sessions).
Wall's perfect for this!
But after a re-install of Garuda Linux, it stopped working. I had thought this was just built into KDE Plasma! Worse, there is very little information on the web about this (likely because, again, this is really for multi-user systems). So I thought I'd put this info up where others could reach it more easily.
write messages pop up as KDE Plasma notifications, you will need "KWriteD" installed. It shows up in the System Settings app, under "Notifications", Application Specific Settings (button "Configure), "Local System Message Service".
Hope this helps someone.