telinit, /etc/ringback (answer phone on second call)

[Brandon S. Allbery]

As quoted from <2425 at turnkey.TCC.COM> by sandy at turnkey.TCC.COM (Sanford 'Sandy' Zelkovitz):
+---------------
| In article <8315 at rpp386.Dallas.TX.US>, jfh at rpp386.Dallas.TX.US (The Beach Bum) writes:
| > In article <183 at libove.UUCP> root at libove.UUCP (Jay M. Libove) writes:
| > >Well, I want to use it for my SCO Xenix 2.2.1 system, but it requires
| > >using "telinit", a not-well-supported feature on SCO Xenix 2.2.1.
| > 
| > telinit is an unsupported feature on 2.2.1.  It is used to signal
| > init to re-read the inittab, which is completely unsupported [ from
| > init's perspective ] under 2.2.x
| 
| be run from the inittab without exiting the present run level. SCO
| decided to stay with the old SysIII style using /etc/ttys. Under SysV,
+---------------

Microsoft (not SCO) decided to stay with the V7 init.  System III has an
inittab, although it's different from the System V one in both form and
intent:  there are still run levels (1-6), but init doesn't maintain utmp at
all.  Init is simply and solely a process spawner under System III.

For the curious, here's a slice of a System III /etc/inittab:

1:co:c:/bin/env HOME=/ TZ=EST5EDT LOGNAME=root PATH=/bin:/etc:/usr/bin:/usr/local/bin:/usr/plx /bin/sh</dev/console>/dev/console 2>&1
1:xx::/etc/getty console ! 0 
2:co:c:/etc/getty console b
2:00:c:/etc/getty tty0 c
2:01:c:/etc/getty tty1 c
2:02:o:/etc/getty tty2 c

The init command field (field 3) consists of flags:

c	respawn command ("respawn")
o	do nothing ("off")
k	send "kill -9" to process group if command running
t	send "kill -15" to process group if command running

Usually, one uses "c" for always-running processes, "o" for always-disabled
entries (such as for unused ttys; the effect is that the line is a comment),
and "kto" when an entry is sometimes on and sometimes off (the "kt" makes
sure the currently-running process group gets killed).  It's not as flexible
as System V, but it works and it's somewhat more flexible than V7.  There is
no "telinit" command; one says "init 2" (or whatever) to change init
states.  The only way to find out the current init state is with "ps":

Script started on Sun Nov  6 13:08:36 1988
3 at ncoast:1 % ps -fp 1
    UID   PID  PPID  C   STIME TTY  TIME COMMAND
   root     1     0  0  Oct  8   ?  4:48 INIT 2
3 at ncoast:2 % 
script done on Sun Nov  6 13:08:58 1988

++Brandon
-- 
Brandon S. Allbery, comp.sources.misc moderator and one admin of ncoast PA UN*X
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