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Groups > gnu.bash.bug > #16701

process substitution error handling

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Hi,

It may be a surprise to some that this code here winds up printing
"done", always:

$ cat a.bash
set -e -o pipefail
while read -r line; do
       echo "$line"
done < <(echo 1; sleep 1; echo 2; sleep 1; false; exit 1)
sleep 1
echo done

$ bash a.bash
1
2
done

The reason for this is that process substitution right now does not
propagate errors. It's sort of possible to almost make this better
with `|| kill $$` or some variant, and trap handlers, but that's very
clunky and fraught with its own problems.

Therefore, I propose a `set -o substfail` option for the upcoming bash
5.1, which would cause process substitution to propagate its errors
upwards, even if done asynchronously.

Chet - thoughts?

It'd certainly make a lot of my scripts more reliable.

Jason

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process substitution error handling "Jason A. Donenfeld" <Jason@zx2c4.com> - 2020-08-06 12:05 +0200

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