Xref:	news2.mv.net comp.os.msdos.djgpp:6191
From:	harald DOT mommer AT post DOT rwth-aachen DOT de (Harald Mommer)
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: RAMdisk (was: Bug in stubify.c)
Date:	16 Jul 1996 13:47:14 GMT
Organization:	A (still) poorly-installed InterNetNews site
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	<4rhr20$181v AT rs18 DOT hrz DOT th-darmstadt DOT de> <4s6811$s12 AT news DOT csus DOT edu>
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In article <4s6811$s12 AT news DOT csus DOT edu>,
	gmontem AT sfsu DOT edu (GEORGE ARUGAY MONTEMAYOR) writes:
> I may sound stupid, but what are pipes, and what does the -pipe do?  Ack. 
> I'm not very familiar with all of the command line options, so bear with 
> me.  :(  Anyways, is there a document on all of the command line options 
> GCC supports?

Pipes are something special in UNIX. At example, you redirect standard
output of the first program to the standard input of a second
program. This is the thing you do if you enter "DIR | MORE" in MSDOS.

But unlike UNIX, MSDOS is a single tasking operating system. It cannot
run more than one program at a time. So MSDOS uses temporary files to
simulate real pipes, the output of the first program is redirected
into a temporary file, the first program terminates, the second
program is started with standard input redirected to the temporary
file. All is done sequential. You have a lot of traffic on your hard
disk.

In UNIX all programs involved into a pipe operation are started
simultanously, no temporary files are used, all is done in memory
buffers. If you give gcc the -pipe option, cpp, cc1 and as are started
simulatanously, the output of cpp is given to cc1 by a pipe and the
output of cc1 is given to as by another pipe. No temporary files have
to be written and compilation is speeded up - if you have enough
memory installed to avoid swapping.

Harald
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