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From: harald.alvestrand@elab-runit.sintef.no
Newsgroups: comp.protocols.iso.dev-environ
Subject: Re: Why do daemons fork five times?
Message-ID: <1991Feb18.114233.5473@ugle.unit.no>
Date: 18 Feb 91 11:42:33 GMT
References: <91Feb15.173220est.57761@ugw.utcs.utoronto.ca>
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Reply-To: harald.alvestrand@elab-runit.sintef.no
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You need to read this code carefully (I know, I missed!)


|> 
|> 	if (!(debug = isatty (2))) {
|> 		for (i = 0; i < 5; i++) {
|> 			switch (fork ()) {
|> 			    case NOTOK:
|> 				sleep (5);
|> 				continue;
Note that the CONTINUE matches the FOR, not the SWITCH....
|> 			    case OK:
|> 				break;
This breaks out of the SWITCH.........
|>       if child, _exit(0)........
|> 			    default:
|> 				_exit (0);
|> 			}
|> 			break;
This breaks out of the FOR...............
|> 		}
|> 

So, the code says "try five times to fork in intervals of 5 seconds".
One may suspect that ISODE was developed on a machine with limitations on
how many processes could be started at any one time, so that failed fork
calls were common.

You are right about the DUPs of course, but I would like to know what
errors can occur with a DUP, as long as /dev/null is a valid file...


                   Harald Tveit Alvestrand
Harald.Alvestrand@elab-runit.sintef.no
C=no;PRMD=uninett;O=sintef;OU=elab-runit;S=alvestrand;G=harald
+47 7 59 70 94