Date: Wed, 13 Jun 2007 16:32:31 +0300 From: Danny Braniss <danny@cs.huji.ac.il> To: David Wolfskill <david@catwhisker.org> Cc: Garrett Cooper <youshi10@u.washington.edu>, hackers@freebsd.org Subject: Re: Using shell commands versus C equivalents Message-ID: <E1HySxb-000PIg-89@cs1.cs.huji.ac.il> In-Reply-To: <20070613123213.GE98927@bunrab.catwhisker.org> References: <466F86C6.7010006@u.washington.edu> <20070613123213.GE98927@bunrab.catwhisker.org>
next in thread | previous in thread | raw e-mail | index | archive | help
>
> --Rgf3q3z9SdmXC6oT
> Content-Type: text/plain; charset=us-ascii
> Content-Disposition: inline
> Content-Transfer-Encoding: quoted-printable
>
> 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
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?E1HySxb-000PIg-89>