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From: bogatko@lzga.ATT.COM (George Bogatko)
Newsgroups: comp.unix.questions
Subject: Re: redirecting standard i/o from an exec'ed programme
Summary: crow eating example
Keywords: popen, io, exec, system
Message-ID: <2021@lzga.ATT.COM>
Date: 23 Aug 90 12:45:51 GMT
References: <377@fe2o3.UUCP> <2007@lzga.ATT.COM> <3939@auspex.auspex.com>
Organization: AT&T BL Middletown/Lincroft NJ USA
Lines: 19

In article <3939@auspex.auspex.com>, guy@auspex.auspex.com (Guy Harris) writes:
> >Popen is expensive.  It requires a shell for 'system' and then
> >another shell to run your request in.
> 
> It doesn't use "system()" on any UNIX implementation I've used (V7, BSD,
> S3, S5, etc.).  It just runs *one* shell, which runs your command. 

Absolutly right.  I goofed.  What we saw was an explosion of 
fork/exec combinations when the application made heavy use of 'popen'
instead of directly using fork/exec.

I should have said:

	"Popen is expensive.  It requires a fork/exec to invoke the
	shell and then another fork/exec to run your request."

Crow is not digestable, by the way.

GB.