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From: kucharsk@uts.amdahl.com (William Kucharski)
Newsgroups: comp.unix.questions
Subject: Re: Unix doesn't work !
Summary: Close unused fd's first
Message-ID: <102hQ07cq71010PFlGc@amdahl.uts.amdahl.com>
Date: 25 Mar 89 05:37:30 GMT
References: <407@retix.retix.COM>
Reply-To: kucharsk@amdahl.uts.amdahl.com (William Kucharski)
Distribution: usa
Organization: Amdahl Coup, UTS Products Hen House
Lines: 27

In article <407@retix.retix.COM> randy@retix.retix.com.UUCP (Miyazaki Randy) writes:
 >Why does the child read not terminate with a End of File indication ?
 >Bizzarely enough, the program hangs both under BSD 4.3 and
 >S5R3 (Interactive VP/IX 1.0.6). This seems to contradict any
 >documentation on pipes I have seen.
 >
Although it's not mentioned in the man page, you should close the file
descriptor you are _not_ using on your end of the pipe (i.e., if you are the
parent, close pipefd[1]; if you're the child, close pipefd[0].)  If you change
your code from

 >      len = read(pipefd[0], &buf, 1);

to
	close(pipefd[1]);
        len = read(pipefd[0], &buf, 1);

it does work...
-- 
					William Kucharski

ARPA: kucharsk@uts.amdahl.com
UUCP: ...!{ames,decwrl,sun,uunet}!amdahl!kucharsk

Disclaimer:  The opinions expressed above are my own, and may not agree with
	     those of any other sentient being, not to mention those of my 
	     employer.  So there.