Path: utzoo!attcan!uunet!naitc!karl
From: karl@naitc.uucp (Karl Denninger)
Newsgroups: comp.unix.i386
Subject: Re: How do you boot Interactive's SysV in single user mode???
Summary: Microport USED to allow you to have something in /etc/rc
Message-ID: <1990Aug20.152436.29851@naitc.uucp>
Date: 20 Aug 90 15:24:36 GMT
References: <26049@bellcore.bellcore.com> <brando.650761253@uicslsb.csl.uiuc.edu> <1990Aug16.160941.17784@ddsw1.MCS.COM> <3915@auspex.auspex.com>
Reply-To: karl@naitc.naitc.com (Karl Denninger)
Organization: A.C. Nielsen Bannockburn, IL
Lines: 32

In article <3915@auspex.auspex.com> guy@auspex.auspex.com (Guy Harris) writes:
>>A more elegant solution(?) might be to edit the binary /unix, changing the
>>text string /etc/inittab to something else; ... I HAVEN'T TRIED THIS.
>
>Not surprising, since I *very* much doubt it'd work.  "/unix" doesn't
>know beans about "/etc/inittab"; all it knows about is "/etc/init" (or
>wherever your particular UNIX flavor puts it - S5R3.x for the 386
>probably still has it in "/etc").

Used to be that Microport SV/AT would have signals enabled in the "rc"
scripts which ran when the system came up - which leads to the hack:

trap "init s" 2
echo "System going multiuser in 15 seconds, hit <delete> if wrong"
sleep 15
trap "" 2

Which would have the effect of allowing an abort to single user mode during
the boot sequence.  Worked real well for me, and never was I without a way
to single user mode when it was needed.

You put this right at the front of the rc2 script....

Now, ISC (and presumably others) ignore signals during the boot process,
making it difficult at best to perform this kind of thing.

--
Karl Denninger	AC Nielsen
kdenning@ksun.naitc.com
(708) 317-3285
Disclaimer:  Contents represent opinions of the author; I do not speak for
	     AC Nielsen on Usenet.