Capture non-zero exit code from named pipe

Question

The following toy script (tmp.sh) exits with code 0 even if the process sent to the named pipe fails. How can I capture the non-zero exit code from the named pipe? Or more in general, the fact that something has gone wrong?

#!/bin/bash

set -eo pipefail

mkfifo mypipe
FOOBAR > mypipe &

cat mypipe

---

Run and check exit code:

bash tmp.sh
tmp.sh: line 6: FOOBAR: command not found

echo $? # <- Exit code is 0 despite the "command not found"!

Answer 1

You need to capture process id of background process and wait for it to set the correct exit status:

#!/bin/bash
set -eo pipefail

rm -f mypipe
mkfifo mypipe

FOOBAR > mypipe &
# store process id of above process into pid
pid=$!

cat mypipe

# wait for background process to complete
wait $pid

Now when you run it:

bash tmp.sh
tmp.sh: line 6: FOOBAR: command not found
echo $?
127