Re: Why tail coreutil cannot work as its input is from tee

[Andreas Kusalananda Kähäri]

On Mon, Sep 06, 2021 at 07:38:03AM +0000, Budi wrote:
> How come tail coreutil cannot work as its input is from tee
> 
> $ echo -e '9\n4\n3\n2\n8\n7\n3\n1' |tail -1
> 1
> 
> But :
> 
> $ echo -e '9\n4\n3\n2\n8\n7\n3\n1' |tee >(head -1) |tail -1
> 9
> 
> Please help explain

I don't see how this is a bug report against the bash shell.

Note that the output from your pipeline is non-deterministic:

        $ echo -e '9\n4\n3\n2\n8\n7\n3\n1' |tee >(head -1) | tail -1
        1
        $ echo -e '9\n4\n3\n2\n8\n7\n3\n1' |tee >(head -1) | tail -1
        9

This is on an OpenBSD system.  This depends on whether tee has a chance
of outputting the complete data from echo to its standard output first,
before the head outputs its data.  With GNU tools, I can't get the
pipeline to output 1, but I know there's a chance it may eventually
output 1 rather than 9.

-- 
Andreas (Kusalananda) Kähäri
SciLifeLab, NBIS, ICM
Uppsala University, Sweden

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