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From: torek@elf.ee.lbl.gov (Chris Torek)
Newsgroups: comp.unix.internals
Subject: Re: Regular pipe vs. Named Pipe
Message-ID: <14079@dog.ee.lbl.gov>
Date: 8 Jun 91 20:02:53 GMT
Article-I.D.: dog.14079
References: <1991Jun7.195953.27744@digi.lonestar.org>
Reply-To: torek@elf.ee.lbl.gov (Chris Torek)
Organization: Lawrence Berkeley Laboratory, Berkeley
Lines: 22
X-Local-Date: Sat, 8 Jun 91 13:02:53 PDT

In article <1991Jun7.195953.27744@digi.lonestar.org>
cfoughty@digi.lonestar.org (Cy Foughty) writes:
>What are the differences between a regular pipe and a named pipe?

The main difference is that one has a name and one does not.  The only
other substantive difference is that a regular pipe can only be `half-
open' when it is shutting down (either all readers or all writers have
closed their descriptors, and none will ever gain a new one), while a
named pipe is half-open at the beginning (only a reader, or only a
writer, exists).  This makes named pipes more complicated.

>Which type of pipe is faster and by how much?
>Which is faster, a named pipe or a message queue?
>Does a named pipe always go to disk or only when the allocated
>memory is exhausted?

All of these are implementation-dependent.  The only way to find out
is to try it on each implementation (or read the implementation's
source, though source-based performance analysis is quite a trick).
-- 
In-Real-Life: Chris Torek, Lawrence Berkeley Lab CSE/EE (+1 415 486 5427)
Berkeley, CA		Domain:	torek@ee.lbl.gov