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From: ka@june.cs.washington.edu (Kenneth Almquist)
Newsgroups: comp.unix.wizards
Subject: Re: STREAMS module / dup question
Message-ID: <8217@june.cs.washington.edu>
Date: 14 May 89 09:28:53 GMT
References: <569@lehi3b15.csee.Lehigh.EDU>
Organization: U of Washington, Computer Science, Seattle
Lines: 24

murrey@lehi3b15.csee.Lehigh.EDU (Erik Murrey) asks:

> What if:
> 	1. I open a STREAM.  [ UNIX System v.3.1 ]
> 	2. I dup that stream, so now I have 2 fd's referring to
> 		that stream.
> 	3. I push a module on one of the fd's.
>
> Questions:
> 	1. Do both of those fd's have that module pushed on it?

Yes.

> 	2. What happens during a fork()?

Both the parent and the child share the stream.  For example, if
the child process pushes a module onto the stream, and then the
parent process does a read from the stream, the input to the
parent process will pass through the module that the child process
pushed onto the stream.

(Disclaimer:  This is what I think it should do.  I haven't actually
tested the code.)
				Kenneth Almquist