From mboxrd@z Thu Jan  1 00:00:00 1970
Message-ID: <3642d6516c1daa93eacc16850ae258e0@collyer.net>
To: 9fans@cse.psu.edu
Subject: Re: [9fans] rc here docs
From: Geoff Collyer <geoff@collyer.net>
In-Reply-To: <01d501c37034$9a184d00$b9844051@insultant.net>
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Date: Sun, 31 Aug 2003 20:19:04 -0700
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I'm not suggesting

	{ echo foo; echo bar; echo baz; echo quux } | cmd

but rather

	echo 'foo
bar
baz
quux' | cmd

Given one echo command to replace one here document, I don't think the
here documents are substantially cheaper than using echo.  With echo,
you have to load echo from disk (modulo caching) and it writes your
message down a pipe.  With a here document, the shell writes the here
document into a temporary file, then attaches that temporary file as
the command's standard input, so the command can read what the shell
just wrote, then eventually the shell removes the temporary file;
again this is all nominally disk i/o.  (To make matters slightly
worse, sh did unaligned writes of lengths not a multiple of 512 to the
temporary files.)  So here documents are not cheap and they do seem to
clutter shells with considerable added complexity.  I could probably
live without them except that bundle uses them, sometimes to transmit
large files that might even exceed Plan 9's ability to pass them as
command-line arguments.