From: "Owen M. Astley" <oma1000@cam.ac.uk>
To: Jan Kroken <jankr@ifi.uio.no>
Cc: zsh-users@math.gatech.edu
Subject: Re: Redirection (<>)
Date: Fri, 7 Aug 1998 17:00:40 +0100 (BST) [thread overview]
Message-ID: <Pine.OSF.3.96.980807165844.1990O-100000@alpha2.poco.phy.cam.ac.uk> (raw)
In-Reply-To: <vhipvecu8dh.fsf@thjazi.ifi.uio.no>
> >From zsh.info:
> `<>WORD'
> Open file WORD for reading and writing as standard input. If the
^^^^^^^^^^^^^^
> file does not exist then it is created.
>
> and here's what happens when I try to use it.
>
> ~/tmp% cat > f
> a b d f
> c d c
> c c d
> e c d
> ~/tmp% sed "s/c/f/g" <> f
> a b d f
> f d f
> f f d
> e f d
> ~/tmp% cat f
> a b d f
> c d c
> c c d
> e c d
> ~/tmp%
>
> And my question is; Why does the output from sed go to stdout?
>
> What does <> really mean?
It means that the file is opened rw as stdin (instead of read-only, as
normal). sed sends its output to stdout.
If you had a program that tried to write to stdin it would normally fail
(presumably), but wouldn't if you used <>.
(Note: I haven't tried this).
Owen
prev parent reply other threads:[~1998-08-07 16:16 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
1998-08-07 15:19 Jan Kroken
1998-08-07 15:52 ` Zefram
1998-08-07 16:00 ` Owen M. Astley [this message]
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