The ppp(8) manual says
All external commands (executed via the "shell" or "!bg" commands) are executed.... So "shell" is for foreground and "!bg" is for background commands. You may want to wait for some things, and not for others (so different scripts run by "shell" and, subsequently, "!bg"). Choose wisely.Yes, and no. You still want rc scripts to work by themselves when you choose to restart an individual service. And one of the places where you restart those services (with
service xxx restart) is in the script that gets invoked by the "link-up" asynchronous event. You manage this on a case by case basis. Make sure that the rc script does not compromise the system if the Internet is not up, and does what you want when the Internet is up.