Many references are made to BSD or BSDs when they may be inaccurate if BSDs means other than FreeBSD.
"You won't find init.d or any of the runlevel subdirectories on a BSD system. Instead, the system startup scripts live in /etc/rc.d, and the startup scripts for third-party applications stay in /usr/local/etc/rc.d." doesn't apply to openBSD.
My job calls for me to use several Linuxes (Linuces?) and several *BSDs so it didn't fool me.
Others may have a problem. Maybe substitute FreeBSD for all " BSD" references. Even then I'm not up on 5.? so that may be inaccurate.