From owner-freebsd-questions Sat Jan 26 0:29:45 2002 Delivered-To: freebsd-questions@freebsd.org Received: from Mail6.nc.rr.com (fe6.southeast.rr.com [24.93.67.53]) by hub.freebsd.org (Postfix) with ESMTP id 6570A37B404 for ; Sat, 26 Jan 2002 00:29:40 -0800 (PST) Received: from i8k.babbleon.org ([66.57.85.154]) by Mail6.nc.rr.com with Microsoft SMTPSVC(5.5.1877.687.68); Sat, 26 Jan 2002 02:02:28 -0500 Received: by i8k.babbleon.org (Postfix, from userid 111) id C8FD93FE5; Sat, 26 Jan 2002 02:01:14 -0500 (EST) Content-Type: text/plain; charset="iso-8859-1" From: Brian T.Schellenberger To: Cliff Sarginson , freebsd-questions@FreeBSD.ORG Subject: Re: shells confusion Date: Sat, 26 Jan 2002 02:01:14 -0500 X-Mailer: KMail [version 1.3] References: <20020126020430.P175-100000@BLAST> <20020126035658.GC1290@raggedclown.net> In-Reply-To: <20020126035658.GC1290@raggedclown.net> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Message-Id: <20020126070114.C8FD93FE5@i8k.babbleon.org> Sender: owner-freebsd-questions@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG On Friday 25 January 2002 10:56 pm, Cliff Sarginson wrote: > On Sat, Jan 26, 2002 at 02:18:16AM +0200, Bernie wrote: > > hi, > > > > i'm planning to learn shell programming but i'm not sure > > on which one to choose... > > > > i've been reading in the 'FreeBSD unleashed' that people > > wanting to do shell programming should stay away from > > c-shell as it's realy good for interactive, but very bad > > for scripts. is this true? > > Yes and Yes. I would not agree with this at all. I find csh much more readable/sensible than /bin/sh for interactive use. Spaces don't matter; if statements are vastly more readable, etc. Now for really complex "shell" programming I use perl, but C shell is, IMHO, a lot easier to write and read than /bin/sh. There *is* one severe problem with csh that I know of: the quoting rules are just plain broken; if you get into nested quotes things get screwy quickly. I work around this with set Q = "'" set QQ = '"' set $S = '$' at the top of my scripts, but I freely admit that it is completely stupid that I should have to do so, but writing if ($a > 4) then echo "$a is greater than 4" endif vs. if [[eval $a > 4]];; echo "$a just tell me that's more readable. I dare you." fi (or whatever--the syntax is inexact) it just seems to be to be no contest: csh wins, hands-down. Plus the convenience of if ($a =~ foo*) vs. (as far as I can tell) having to do a switch just for string tests -- again, csh is the scripting shell for me. EXCEPT that on non-BSD systems, csh isn't necessarily always avaialble. Other than that, when push comes to shove, this is more a matter of personal opinion than any inherent superiority of one shell over another. (Well, bash or zsh, which postdate /bin/sh and csh might be better and of course tcsh is better than original csh . . . but /bin/sh is really terrible for scripting if you ask me, never mind that it's widely used.) > > also, looking into the scripts in /etc, i see a line on the > > top saying 'bin/sh'. so are they all written in 'sh' and > > not csh ? if so, why freebsd comes with csh as default? > > /bin/sh is the Unix common denominator of shells, so scripts > get written in it. They are not written in csh, because as > stated csh script is unusable for all practical purposes. unusable??????? What on earch are you talking about? I have many dozens of quite usable csh scripts. And they are readable, too. > > You will be opening up another war here on the subject > of which shell should be the default user/root shell. > You may notice that "root" has two entries on the system, > one as "root" with csh as it's shell, and one as "toor" > with sh as it's shell. > > By the way, csh = tcsh on FreeBSD, I don't know if there > is a "pure" csh around anymore. The huge difference between > csh as was, and tcsh, being that tcsh is usable (ducks). The main difference is the interactive history. Lots of other bells & whistles, but csh was usable, too. A huge, huge improvement for both interactive and scripted use over the original /bin/sh. > In summary, *not* the csh for scripts. > Learn sh for scripts. I agree that you might have to (unfortunately) learn a mininum of sh for scripts, because the vast majority of scripts are written in it, but it's definately a matter of opinion whether they *should* be written in it. > Use bash or tcsh for your day to day interactive use. > > I think most people will give you more or less the same > advice, the choice of tcsh or bash will mostly depend on > their personal Unix backgrounds as much as anything else. -- Brian T. Schellenberger . . . . . . . bts@wnt.sas.com (work) Brian, the man from Babble-On . . . . bts@babbleon.org (personal) http://www.babbleon.org -------> Free Dmitry Sklyarov! (let him go home) <----------- http://www.eff.org http://www.programming-freedom.org To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message