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Re: Why `echo -n hello | while read v; do echo $v; done' prints nothing?
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From: |
Greg Wooledge |
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Subject: |
Re: Why `echo -n hello | while read v; do echo $v; done' prints nothing? |
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Date: |
Thu, 2 Dec 2010 10:49:55 -0500 |
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User-agent: |
Mutt/1.4.2.3i |
On Thu, Dec 02, 2010 at 07:04:57PM +0800, Clark J. Wang wrote:
> Following command also prints nothing, confused :(
>
> for ((i = 0; i < 10; ++i)); do echo -n " $i"; done | while read v; do echo
> $v; done
The output from the first command in the pipeline does not end with a
newline. Therefore, 'read' in the second command returns 'failure'
(non-zero) when it reads the first line of input, and your loop never
iterates.