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To:	rc@hawkwind.utcs.toronto.edu
Date:	Tue, 8 Dec 1992 12:17:55 -0500
Subject: Here documents
From:	raymondc@microsoft.COM
Message-Id: <9212171135.aa29990@ingate.microsoft.COM>

: { echo 'cat <<EOF' ; echo '$foo' ; echo EOF } | rc

Which can much more readably be written as

	rc -c 'cat <<EOF
	$foo
	EOF
	'
	
:	3. Should a here document be read from a command's stdin,
:	rather than the shell input?  Would this break any existing scripts?
:	This would allow example [2] to work.

I vote no.  Here documents should be read from the shell input.
(I.e., the place the did the "<<" or "<<<".)

Otherwise, you can't do stuff like...

	# xpend -- prepend and append goop

	cat <<EOF			# add the header
	------------------------------------------------------------
	Item $1
	------------------------------------------------------------
	EOF
	cat				# let the body pass through
	cat <<EOF			# add the footer
	------------------------------------------------------------
	End of item $1
	------------------------------------------------------------
	EOF

If the here document took its input from stdin instead of
the shell command input, this script would break.

: I am intrigued that such subtleties exist in an apparently
: straightforward feature of the language.

Here documents (and really-here documents) take their input from
the shell command input; i.e., the place where shell commands are
parsed and executed.  I see no subtleties.  Here documents are
merely a handy abbreviation for a huge sequence of "echo"s.
--
Raymond (FOB --- Friend of Byron) Chen