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Re: Fwd: read builtin return non-zero status reason


From: Cuong Manh Le
Subject: Re: Fwd: read builtin return non-zero status reason
Date: Wed, 24 Feb 2016 21:45:02 +0700

Why there's no different? EOF means you have nothing to read.

If you put it into a while loop context:

while read -d '' line; do echo "$line"; done < <(printf '1')

give you nothing. There's only one read in this case

There's data to read, but read return non-zero there. it doesn't find delimiter, does it?

Compare to:

while read -d '' line; do echo "$line"; done < <(printf '1\0')

give you 1. There two read, the first *read* 1, the second reached EOF, cause the while loop terminated.

On Wed, Feb 24, 2016 at 9:24 PM, Greg Wooledge <address@hidden> wrote:
> > It's the same thing.  "Reached EOF before seeing the delimiter" is the
> > whole, combined reason.
>
> How can we verify it?
>
> Stephane Chazelas also have the same opinion with me in his answer
> http://unix.stackexchange.com/a/265484/38906, that's error came from no
> delimiter found.

You're confused.  There is no difference between the two things.  They
are the two sides of the same check.

When read reads from stdin, it will either encounter EOF, or it won't.
If it encounters EOF, it returns nonzero.  If it doesn't encounter EOF,
it looks to see if it found the delimiter character.  If so, it returns
zero.  If not, it continues reading.

That's literally all of the possible outcomes, apart from non-EOF errors.


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