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Path: utzoo!watmath!clyde!burl!ulysses!mhuxl!ihnp4!gargoyle!toby
From: toby@gargoyle.UChicago.UUCP (Toby Harness)
Newsgroups: net.unix-wizards
Subject: Re: Why doesn't this work (fork and pipe problem) ???
Message-ID: <170@gargoyle.UChicago.UUCP>
Date: Wed, 18-Jul-84 14:08:24 EDT
Article-I.D.: gargoyle.170
Posted: Wed Jul 18 14:08:24 1984
Date-Received: Thu, 19-Jul-84 03:28:00 EDT
References: <342@mddc.UUCP>
Organization: U. Chicago - Computer Science
Lines: 25

(sorry, but I can`t seem to reply)

Well, you didn`t close the 'unused' sides of the pipe.

	pipe(pipefd);

	switch(pid=fork())
	...
	case 0:					/* child */
========>   close(pipefd[0]);	/* not necessary, just good practice */
	    close(1);
	    dup(pipefd[1]);
	    printf("about to exec who\n"); 
	    execlp("/bin/who", "who", (char*)0);
	    printf("could not execute\n");
	    exit(0);

	default:				/* parent */
========>   close (pipefd[1]);	/* necessary */
	    close(0);
	    dup(pipefd[0]);
	...

Toby Harness		Ogburn/Stouffer Center, University of Chicago
			...ihnp4!gargoyle!toby