Attempting to understand behavior of /bin/ksh's read command
Dave Ihnat
ignatz at dminet.com
Thu Nov 3 16:46:45 UTC 2005
On Thu, Nov 03, 2005 at 11:07:59AM -0500, Virden, Larry W. wrote:
> $ echo aa bb cc dd | read a b c d
>
> $ echo $a
>
> /bin/ksh: a: parameter not set
Nothing's wrong; it's doing just what you told it to do. You just told
it to do the wrong thing.
You told it to spawn a subshell--note the pipe--which certainly read
the output from the echo command, set its own variables a, b, c, and
d--and then destroyed them when it exited. You can't set variables in
a parent from a child.
If you type:
read a b c d
This is a test
echo $a $b $c $d
you'll see it's parsed them properly; everything is in the same shell.
So how do you redirect input ? There are various ways.
exec 0<filename
echo aa bb cc dd | (
read a b c d
echo $a $b $c $d
)
and so on.
Cheers,
--
Dave Ihnat
ignatz at dminet.com
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