Date: Mon, 30 Oct 2000 16:15:03 -0500 From: "Andresen,Jason R." <jandrese@mitre.org> To: Joe Greco <jgreco@ns.sol.net> Cc: Greg Black <gjb@gbch.net>, hackers@FreeBSD.ORG, ryan@sasknow.com, andrew@ugh.net.au Subject: Re: Logging users out Message-ID: <39FDE4D7.1020C4B2@mitre.org> References: <200010302102.PAA81188@aurora.sol.net>
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Joe Greco wrote:
>
> > > I wrote a little line program to do a revoke(), it was basically
> > >
> > > int main(int argc, char *argv[]) { revoke(argv[1]); }
> > >
> > > Now this doesn't kill a darn thing. And you should be aware of it! But it
> > > does forcibly "close" any open fd's pointing at the tty in question, and
> > > most programs will get the hint and go away.
> >
> > Not all programs, and that can lead to all sorts of problems
> > with processes that never die. There are many stories of this
> > happening with vi, for example.
>
> That's why I said, "most programs".
>
> > > For some uses, especially predictable uses, this is probably a lot simpler
> > > and a lot more foolproof.
> >
> > Simple: yes. Foolproof: definitely no.
>
> Uh, well, "foolproof" != "calling ps and awk and grep and looking for
> processes". For ANY definition of foolproof.
>
> And it is certainly foolproof from the point of view that there's no way
> in hell for the session not to be terminated, unlike some ps garbage I've
> seen.
Unfortunatly, sometimes when processes suddenly lose stdin/stdout, they
jump into infinate loops and start eating cpu cycles like crazy. I'd
hate
to see what happens when you kill off a significant number of people
running
these poorly behaved programs. FVWM95 Taskbars used to be notorious for
this,
I remember seeing upwards of a dozen of them vying for CPU time on some
lab
machines.
--
_ _ _ ___ ____ ___ ______________________________________
/ \/ \ | ||_ _|| _ \|___| | Jason Andresen -- jandrese@mitre.org
/ /\/\ \ | | | | | |/ /|_|_ | Views expressed may not reflect those
/_/ \_\|_| |_| |_|\_\|___| | of the Mitre Corporation.
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