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Message-ID: <3B37D068.1F797DA8@agilent.com>
Date: Mon, 25 Jun 2001 16:59:36 -0700
From: Earl Chew <earl_chew AT agilent DOT com>
Organization: Agilent Technologies
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To: Randall R Schulz <rrschulz AT cris DOT com>
Cc: cygwin AT cygwin DOT com
Subject: Re: Shell avoidance in make-3.79.1-3
References: <3B37B58B DOT F87EA366 AT agilent DOT com>
	 <3B37B58B DOT F87EA366 AT agilent DOT com> <5 DOT 1 DOT 0 DOT 14 DOT 2 DOT 20010625161345 DOT 0257c1d8 AT pop3 DOT cris DOT com>
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Randall R Schulz wrote:
> What are you trying to do? What do you mean by "/bin/sh avoidance?"
> 
> Make has no ability to interpret commands, and relies on a shell to do 
> that for each command it decides to invoke.

I you look at the source code (construct_command_argv in in job.c)
you'll find some code that looks carefully at the command line.

If the command line is sufficiently simply (eg sleep 15), make
will perform an optimization whereby it starts the command
directly. That is, instead of:

	sh -c 'sleep 15'

make will invoke the following directly:

	sleep 15

thus avoiding the overhead of a fork/exec of /bin/sh.

Earl
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> Earl Chew                              http://www.agilent.com        |
> Agilent Technologies                   mailto:earl_chew AT agilent DOT com  |
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