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From: emmonsl@athena.ecs.csus.edu (L. Scott Emmons)
Newsgroups: comp.unix.programmer
Subject: Re: how to use pipes (was: Re: system() question)
Message-ID: <1991Mar7.180531.7907@csusac.csus.edu>
Date: 7 Mar 91 18:05:31 GMT
References: <1991Mar3.175234.11716@csusac.csus.edu> <1991Mar3.214844.15444@csusac.csus.edu> <5866:Mar604:22:3791@kramden.acf.nyu.edu>
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In article <5866:Mar604:22:3791@kramden.acf.nyu.edu> brnstnd@kramden.acf.nyu.edu (Dan Bernstein) writes:
>This is, of course, because you aren't waiting for the child to finish.


Actually, it does finish...the child closes the pipeline down when it is done.
The read() reads unless eof, which it only returns when the write end of the
pipeline is closed (it blocks if the pipeline is open with no data in it).
I just did it all implicitly...If anyone can come up with an example where
this wouldn't work please let me know. (except the obvious, where the child
doesn't close the pipe, of course...but then, you are changing the
environment of the usage, of course)

Remember also, that I ignored all the return codes for simplicity in the
examples.

Check out my second version, it works the same, but is easier to see how I
implemented this.

			L. Scott Emmons
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