Usr/local/etc/rc.d

/usr/local/etc/rc.d isn't actually a config file, it's a directory. Any executable shell script ending in .sh in this directory will be executed (using the bourne shell) with the argument "start" when the system boots, and again with the argument "stop" when the system is shut down.

You may find this generic rc.d script (shown as I use it to start bind9) handy for general purpose use:

#!/bin/sh

case "$1" in
start)
        /usr/sbin/named -c /etc/namedb/named.conf &
        echo "bind9"
        exit 0
        ;;
stop)
        exec killall named
        ;;
*)
        echo "Usage: `basename $0` {start|stop}" >&2
        exit 64
        ;;
esac