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From: Valentin Lab <valentin.lab@kalysto.org>
Newsgroups: gnu.bash.bug
Subject: process substitution bug or difference from bash 4.4
Date: Wed, 25 Mar 2020 15:35:57 +0100
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Hi,

I have encountered an issue when running some bash code from 4.4 on a 
bash 5 ... I've managed to pinpoint the exact issue on my end.

Here are 2 functions that are quite similar, except the usage of "{ ; }" 
around the "cat":

## ----------------
ouch() {
     cat < <(echo bar)
     cat "$1"
}

ouch2() {
     { cat; } < <(echo bar)
     cat "$1"
}
##----------------


Runnning this will give the same output on bash 4.4 and 5:


$ ouch <(echo "foo")
foo
bar


And by replacing "ouch" by "ouch2", I have the same output in bash 4.4 .

But running it on bash 5 will fail:

$ ouch2 <(echo "foo")
bar
cat: /dev/fd/63: No such file or directory


Is that expected ? I'd be happy to know about the rationale behind this 
(and the change) if this is expected.

Many thanks,

Valentin Lab