[TUHS] Early supported UNIX manual

[Phil Budne]

Matt G wrote:
> One area of immediate curiosity for me is the init system, whether the pages suggest it is more in line with research (rc and ttys files) or TS (inittab, runlevels).

The init (VII) page mentions /etc/rc and refers to ttys (V) which says the file
consists of lines with three characters (enable, tty name, getty arg)

getty (VII) describes behaviors for 0, -, 1, 2

The one interesting bit in section (II) is lock (system call 62.) that
implements semaphores with subfunctions lock/unlock/tlock, all of
which take a non-negative semaphore ID called a flag.