Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!decwrl!shelby!Portia!forel!karish
From: karish@forel.stanford.edu (Chuck Karish)
Newsgroups: comp.unix.questions
Subject: Re: Some csh how-to, please
Keywords: csh C-shell shell programming unix read
Message-ID: <1175@Portia.Stanford.EDU>
Date: 29 Mar 89 03:43:56 GMT
References: <2127@pikes.Colorado.EDU> <7467@thorin.cs.unc.edu>
Sender: USENET News System <news@Portia.stanford.edu>
Reply-To: karish@forel.stanford.edu (Chuck Karish)
Organization: Mindcraft, Inc.
Lines: 51

In article <7467@thorin.cs.unc.edu> white@white.cs.unc.edu
(Brian T. White) wrote:
>In article <2127@pikes.Colorado.EDU>, pklammer@pikes.Colorado.EDU
(Peter Klammer) writes:
>> Could someone please tell me how to read a file line at a time
>> into the C shell?

>To read a file one line at a time, try
>
>foreach p ( "`cat file`" )
>	set line=`echo $p`
>	(commands acting on $line)
>end

This fails if 'file' is longer than the allowable length for an
input line.

The following script fragment reads standard input up to a magic cookie
(I don't know how to detect EOF in csh):

#! /bin/csh

set fie=1
while ( "$fie" != "@" )
	set fie=$<
	echo A $fie
end

If this is in an executable file called 'foo', the command would look like

	(cat file; echo "@") | foo

Note that, in csh, it's not possible to pipe to a loop inside the
script, and the script doesn't get a return value from the 'set' command.
An sh script to do this job would look like

cat file |
while read fie
do
	echo A $fie
done

No magic cookies needed; 'read fie' fails at EOF.
A pipe or redirect after 'done' receives the entire output of the loop.

csh is OK as an interactive command line interpreter.  As a programming
language, it's not so hot.   My advice would be to get a copy of
Kernighan and Pike, and use sh instead.

	Chuck Karish	hplabs!hpda!mindcrf!karish	(415) 493-7277
			karish@forel.stanford.edu