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From: bet@orion.mc.duke.edu (Bennett Todd)
Newsgroups: comp.unix.wizards
Subject: Re: csh problem involving nested ifs?
Message-ID: <15004@duke.cs.duke.edu>
Date: 17 Jul 89 19:50:58 GMT
References: <20243@adm.BRL.MIL> <5016@ficc.uu.net> <3171@quick.COM>
Sender: news@duke.cs.duke.edu
Reply-To: bet@orion.mc.duke.edu (Bennett Todd)
Organization: Diagnostic Physics, Radiology, DUMC
Lines: 54
In-reply-to: srg@quick.COM (Spencer Garrett)

In article <3171@quick.COM>, srg@quick (Spencer Garrett) writes:
>In article <5016@ficc.uu.net>, peter@ficc.uu.net (Peter da Silva) writes:
>
>-> generate_a_list_of_file_names |
>->   while read FNAME
>->   do
>->     do_something_with FNAME
>->   done
>-> 
>-> is second nature. And it's impossible in csh without massive inconvenience.
>-> By comparison, having TEST and EXPR builtin is a minor optimisation.
>
>What are you talking about?  It's easy and much more natural under csh.
>
>foreach fname (`generate_a_list_of_file_names`)
>	do_something_with_fname
>end

I am *so* glad bash is out; I used to use a C-shell for interactive work
just to get history and job control; I was always having to fire up
/bin/sh to do serious looping work. Here are some things csh croaks on:

	find ... -print | while read filename;do
		...
	done

If you try rewrite that as

	foreach f (`find ... -print`)
		...
	end

csh will bomb on command line too long.

	IFS=:
	while read login passwd uid gid gcos home shell;do
		# process /etc/passwd with fields broken down
	done </etc/passwd

I wouldn't know how to try that in csh -- without running a separate
invocation of sed(1) over /etc/passwd once per record.

	for f in ... # or while ...
		...
	done &

csh won't let me background an entire loop.

Basically, I get the impression that csh's attempts at programming
constructs are afterthoughts hacked in imperfectly, rather than properly
parsed grammar constructs.

-Bennett
bet@orion.mc.duke.edu