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Re: When reading less than wanted characters, "read" does not detect NUL bytes

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  Re: When reading less than wanted characters, "read" does not detect NUL bytes Greg Wooledge <wooledg@eeg.ccf.org> - 2018-06-15 09:07 -0400

#14238 — Re: When reading less than wanted characters, "read" does not detect NUL bytes

On Fri, Jun 15, 2018 at 03:03:21PM +0200, Davide Brini wrote:
> $ printf 'a\x00\x00bc' | { while IFS= read -d '' -n 2 var; do echo "read: $var, length: ${#var}"; done; }
> read: a, length: 1
> read: , length: 0
> read: bc, length: 2
> 
> I would expect there to be another read of length 0 between the "a" and the
> "bc".

Seems correct to me.  You asked it to stop reading when it finds a NUL
or when it has read 2 characters.  The first time, they both happen at
the same time, and you end up with "a", and two bytes have been consumed.

The second time, it happens after reading the NUL byte, so you get "" and
a total of three bytes have been consumed.

The third time, you read "bc", and all the bytes have been consumed.

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