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Date: Sat, 02 Dec 2000 10:12:56 -0700
From: Wes Peters <wes@softweyr.com>
Organization: Softweyr LLC
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To: Charlie & <root@int80h.org>
Cc: hackers@FreeBSD.org
Subject: Re: pipe
References: <20001202085127.A301@int80h.org>
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Charlie & wrote:
> 
> Sorry if this is a dumb question, but after years of DOS programming, I
> am still discovering the subletiest of Unix:
> 
> When I create a pipe, do I have to use it for interprocess communication
> only, or can the same process write to one end and later read from the
> other?
> 
> What I am looking for is to use it as a FIFO-style buffer. Instead of
> allocating and reallocating memory, let the system worry about how
> much memory the data needs. This is for a two (or more) pass compiler,
> which reads from stdin and writes to stdout. It does not know how much
> data it still has coming in, so it has no idea how much memory it needs
> to store information in, yet after one pass it needs to read it in the
> same order it was written (FIFO).
> 
> If this is possible, is there a limit as to how much I can write to the
> pipe before I start reading it, or is it limitless (within reason, of
> course)?

Yes, you can read from your own pipe, and yes the buffering availabe in
the pipe is limited.  IIRC, the pipe size is 8K.

-- 
            "Where am I, and what am I doing in this handbasket?"

Wes Peters                                                         Softweyr LLC
wes@softweyr.com                                           http://softweyr.com/


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