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For a specific shell script, I need a functionality like in this simplified example:

{ replies=`echo output > >(cat >&3; echo reply1) 2> >(cat >&2; echo reply2)` ;} 3>&1

Obivously, I would like $replies to be something like reply1 reply2, but the "second" stream never gets into the variable but comes out at STDOUT:

output
reply2
$ echo $replies 
reply1

It this a bug or a restriction, and how can I work around it?

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1 Answer 1

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Swapping the order of redirections fixes the "problem":

$ { replies=$(echo output  2> >(cat >&2; echo reply2) > >(cat >&3; echo reply1)); } 3>&1
output
$ echo $replies
reply1 reply2

The "problem" in your example is that when cat >&2; echo reply2 is executed the standard output is already redirected to >(cat >&3; echo reply1). As a result the output of echo reply2 goes to cat >&3.

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1 Comment

I actually thought that I tested that some time ago and that it did not work ... but obviously I'm wrong, it works fine for me. Thank you also for the explanation, I even understand now why this is so.

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