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From: gwyn@brl-tgr.ARPA (Doug Gwyn <gwyn>)
Newsgroups: net.lang.c
Subject: Re: An example of creeping featurism
Message-ID: <5863@brl-tgr.ARPA>
Date: Sat, 17-Nov-84 21:56:23 EST
Article-I.D.: brl-tgr.5863
Posted: Sat Nov 17 21:56:23 1984
Date-Received: Tue, 20-Nov-84 05:40:50 EST
References: <704@reed.UUCP>
Distribution: net
Organization: Ballistic Research Lab
Lines: 7

> ... a friend of mine needed a program to wait
> for a specified process, berkeley kernels let you do this
> by using kill, just kill a process with sig 0, it returns the
> error status without actually doing anything.  ...

All UNIXes I have ever used (from 6th Ed. on) support this.
It is even documented in the manual these days.