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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: <2019@lzga.ATT.COM>
Date: 23 Aug 90 12:40:22 GMT
References: <377@fe2o3.UUCP> <2007@lzga.ATT.COM> <3939@auspex.auspex.com>
Organization: AT&T BL Middletown/Lincroft NJ USA
Lines: 16

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 'exec' calls
when people used popen instead of directly calling 'fork' and 'exec'.

One exec for the shell, and another exec for the program, if it didn't
involve a pipeline.

Sorry,

GB