From mboxrd@z Thu Jan  1 00:00:00 1970
From: ralph@inputplus.co.uk (Ralph Corderoy)
Date: Thu, 09 Nov 2017 15:04:56 +0000
Subject: [TUHS] redirection wildness in v7
In-Reply-To: <3c417dcc-d3b4-0128-737a-7e510c6d0ffc@gmail.com>
References: <3c417dcc-d3b4-0128-737a-7e510c6d0ffc@gmail.com>
Message-ID: <20171109150456.7D0B1203B0@orac.inputplus.co.uk>

Hi Will,

> Why does the first of these incantations not present text, but the
> second does (word is a file)? Neither errors out.
>
> $ <word | sed 20q
> $ <word sed 20q

That's still the case with modern-day sh(1).

http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_09_01
explains that a simple command doesn't need to result in a command name
to execute.  In your first pipeline, there's nothing to copy the data
from the first subshell's stdin redirected from ./word to the subshell's
stdout that's pipes into sed's stdin.  Adding a command to do the copy
works.

    <word cat | sed 20q

-- 
Cheers, Ralph.
https://plus.google.com/+RalphCorderoy