Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!cs.utexas.edu!sdd.hp.com!decwrl!bacchus.pa.dec.com!decvax.dec.com!zinn!lemuria!darryl
From: darryl@lemuria.MV.COM (Darryl Wagoner)
Newsgroups: comp.unix.questions
Subject: Re: How to tell if a process exists
Message-ID: <1325@lemuria.MV.COM>
Date: 7 Aug 90 01:29:28 GMT
References: <26B867F8.38BB@wilbur.coyote.trw.com>
Reply-To: darryl@lemuria.UUCP (Darryl Wagoner)
Organization: Shecora Associates, Inc. Nashua, NH
Lines: 20

In article <26B867F8.38BB@wilbur.coyote.trw.com> rudoff@mdi.com writes:
>
>In a C program, how do you tell if a certain process exists? A
>kill(0,pid) works only if you own the process (or you're root). It
>seems like such a simple thing to request that it should be part of
>the standard C libraries for unix, but I can't seem to find the right
>thing to use.

No, you can use kill(0,pid) even if you don't own the process.  If the
process is running and own by someone else,  then you get a EPERM error,
if the process doesn't exist then you get ESRCH error, and if the
process is killable by you then kill returns a zero.  The error codes
may be different on Ultrix but you get the idea.


-- 
Darryl Wagoner		darryl@lemuria.MV.COM or uunet!virgin!lemuria!darryl
12 Oak Hill Road
Brookline, NH 03033
Office: 603.672.0736   		Home: 603.673.0578