I have a customized Linux image. When it first boots, it checks for some flags, then should ask if the user on console wants to kick off the setup script. If yes, then run setup, display important output to console, wait for confirm, then continue. If no, then just continue as usual.
How do I create a systemd unit file that will interact with the user on console? Since most systemd units start in parallel, how do I wait until everything is done and then "grab the interaction" prior to the user being presented the usual "login" interface?
The setup is entirely console, not graphical, so no need to deal with any graphical login. I just want to have an interactive menu at the right point in startup.
If I actually knew how systemd initiated the login session, might be easier....