Newsgroups: comp.unix.programmer
Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!ghost.unimi.it!marco
From: marco@ghost.unimi.it (Marco Negri)
Subject: Re: Writing a program that cannot be killed except by reboot
Message-ID: <1991Apr15.113041.3069@ghost.unimi.it>
Organization: Computer Science Dep. - Milan University
References: <444@wrdis01.af.mil>
Distribution: na
Date: Mon, 15 Apr 1991 11:30:41 GMT
Lines: 18

mcgough@wrdis01.af.mil (Jeffrey B. McGough) writes:

>Is there anyway to block ALL signals to a program so that it
>may not be killed by kill???

>I know the manual says that sig 9 may not be caught or blocked
>but I was wondering if there might be a funny (strange, interesting)
>hack to get around this...

	I know one and only one situation in that a process can't be killed
	with SIGKILL signal.
	When it is slept, in kernel mode, with priority < PZERO.
	The second argument of sleep kernel is the "sleep priority".
	If this priority is less than PZERO *all* signal are ignored, but
	the process is slept, not ready.
	Don't exist any method to caugth signal 9 without sleeping the
	process forever (reboot).
	Bye. Marco
-- 
Marco Negri					Phone  : +39-2-7575242
Computer Science Dep. Milan University 		Fax    : +39-2-76110556
Via Moretto da Brescia, 9			Telex  : 335199 - MIDSII
I-20133 Milano - Italy - `92 Europe		E-Mail : marco@ghost.unimi.it