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Examine 4.4BSD (the parent of NetBSD), Solaris 7 (a common SVR4), and NetBSD prior to 1.5

4.4BSD
At boot, kernel runs init(8)
init runs /etc/rc, which calls /etc/netstart (to configure network) and /etc/rc.local for local services
At shutdown where init gets SIGTERM, init sends SIGHUP to each process with a controlling terminal