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From: d89cb@efd.lth.se (Christian Brunschen)
Newsgroups: comp.lang.c
Subject: Filtering I/O -- both of them.
Summary: How can I redirect stdin and stdout to a pipe ?
Message-ID: <1990Jul8.120742.18213@lth.se>
Date: 8 Jul 90 12:07:42 GMT
Sender: newsuser@lth.se (LTH network news server)
Reply-To: d89cb@efd.lth.se (Christian Brunschen)
Organization: Lund Institute of Technology, Sweden
Lines: 38

I'm working an a small program that will function as an i/o filter for
mail (1) -- fyi, so tat all occurrences of 'mail' can be replaced with
'femail' (No, not my idea -- I'm doing this for a friend :)

Anyway, i could use popen(), but that only lets me specify either
stdin or stdout replacement -- not both, the way I need it.

So I thought of :
* creating two pipes
* fork()ing
* in the child process, redirect stdin to one pipe & stdout to the other
* in the cild process, execve() mail(1)
* in the parent process, perform i/o and filtering

BUT (and here's my question) :
how do I actually redirect stdin / stdout to the pipes I created ?

I tried

stdin = fdopen (MyPipe [1], "r");

but that, naturally, didn't work (illegal lhs of assignment)

So, if anyone has any ideas, please tell me; All help will be greatly
appreciated!

aTdHvAaNnKcSe

-- Christian Brunschen

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