Dear Old Farts, I've written a chat system that relies at its core on UNIX's permission system. All the explanations are here: https://the-dam.org/docs/explanations/suc.html I thought it would be of interest to the list as it has one foot in the past (using system primitives from the 70's for access control) and one foot in the future: (optionally) using GNU Guix's declarative configuration to create the necessary users, groups, and files. I know most of you have used (and some maybe still do) talk et al. This system is even simpler, just a forever loop: while /usr/bin/true do read -r line || exit 0 # EOF /usr/bin/echo "$(/usr/bin/date --iso-8601=seconds)"\ "$(printf "%-9s" "$(/usr/bin/id --user --name --real)")" \ "$line" >> /var/lib/suc/"$1" done I'd be happy to hear any comments or to welcome you on the Dam, where we test this stuff. Cheers ! Edouard.