Using shell commands versus C equivalents

[Danny Braniss]

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> On Tue, Jun 12, 2007 at 10:55:18PM -0700, Garrett Cooper wrote:
> > Another simple question (I hope):
> >    Is there any reason why shell commands should be used in place of a=20
> > C command (in this case chmod via vsystem instead of the chmod(2)=20
> > function)? It seems like the fork / exec would be more expensive with=20
> > the shell command, but any area where code could be optimized is more=20
> > than welcome I would think.
> 
> There often are reasons to prefer using shell commands to C.
> 
> There typically exist many tradeoffs involved in evaluating one over the
> other, and "machine efficiency" is not always the highest goal.  (For
> example, it may be better to reduce complexity in favor of having a
> simpler structure that is easier for people to understand and maintain
> with confidence that the changes they make have the desired results.
> This is, of course, not to try to claim that shell scripts are
> inherently easier to understand than C code; that would be a silly
> stance to take.)
> 
> I commend to your attention Geoff Collyer and Henry Spencer's "C News"
> (a successor to Rick Adams' "B News") implementation, a great deal of
> which was written as shell scripts (ca. 1988 or so).
> 
> (Yes, I realize that that was almost 20 years ago, and that it
> didn't involve FreeBSD per se.  Ignoring the lessons of history is
> rather short-sighted and foolish:  despite using shell scripts for
> so much of the "code," the machine I was then running went from
> being extremely busy all the time to having a couple of bursts of
> activity per day for about an hour each time -- with more news
> flowing with C News vs. B News.)
> 

read the question again, though it is not absolutely clear/correct, the question
was:
	chmod(path, mode)
vs
	system("chmod ...")

and not wheather to write a program or a shell script.

danny