From: ralph@inputplus.co.uk (Ralph Corderoy)
Subject: [TUHS] redirection wildness in v7
Date: Thu, 09 Nov 2017 15:04:56 +0000 [thread overview]
Message-ID: <20171109150456.7D0B1203B0@orac.inputplus.co.uk> (raw)
In-Reply-To: <3c417dcc-d3b4-0128-737a-7e510c6d0ffc@gmail.com>
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
next prev parent reply other threads:[~2017-11-09 15:04 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-09 14:34 Will Senn
2017-11-09 15:04 ` Ralph Corderoy [this message]
2017-11-09 15:38 ` Will Senn
2017-11-20 23:38 ` Ralph Corderoy
2017-11-09 15:30 ` Chet Ramey
2017-11-09 21:36 ` Dave Horsfall
2017-11-09 21:39 ` Chet Ramey
2017-11-09 15:30 ` Dan Cross
2017-11-09 15:42 ` Will Senn
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