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Subject: Re: grep < fifo fails
To: cygwin AT cygwin DOT com
References: <d56a12c77ecc441ca7dc2e8e1862145c AT prosa DOT dk>
From: Marco Atzeri <marco DOT atzeri AT gmail DOT com>
Message-ID: <fabf7a9e-43a2-ddd7-ccda-4c32a000c21e@gmail.com>
Date: Wed, 3 Oct 2018 18:50:18 +0200
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Am 03.10.2018 um 17:37 schrieb Ole Tange:
> This works:
>
> $ mkfifo fifo
> $ echo > fifo & grep .  fifo
> [1] 10232
> [1]+  Done                    echo > fifo
>
> But this fails:
>
> $ echo > fifo & grep . < fifo
> [1] 11756
> grep: (standard input): Invalid argument
> [1]+  Done                    echo > fifo
>
> I see the same behavior on MINGW, but I do not see the same behavior on GNU/Linux.
>
>
> Regards,
>
> Ole Tange

I assume it is a consequence of the same problem on files.
You can not use the same source for input and output.

$ echo "prova" > prova.txt

$ cat prova.txt
prova

$ cat prova.txt > prova.txt

$ cat prova.txt

the file was erased



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