I have been using `--print-pid=3` as readiness notification for dbus-daemon for quite a while now on my user services and I haven't had any problems with it so far. IIRC, looking at dbus-daemon code, it actually prints the socket address first then its pid. So, I use the `--print-address=` option to save the socket address to a file for consumption by s6-envdir.
Interesting. But it's also an implementation detail, because dbus-daemon could print its pid at any time, no matter its readiness state. That's why I chose to go with --print-address - but of course reading the code instead
of speculating is the right thing to do :) -- Laurent
