Get exit code of a background process

Question

I have a command CMD called from my main bourne shell script that takes forever.

I want to modify the script as follows:

1. Run the command CMD in parallel

Answer 1

My solution was to use an anonymous pipe to pass the status to a monitoring loop. There are no temporary files used to exchange status so nothing to cleanup. If you were uncertain about the number of background jobs the break condition could be [ -z "$(jobs -p)" ].

#!/bin/bash

exec 3<> <(:)

{ sleep 15 ; echo "sleep/exit $?" >&3 ; } &

while read -u 3 -t 1 -r STAT CODE || STAT="timeout" ; do
    echo "stat: ${STAT}; code: ${CODE}"
    if [ "${STAT}" = "sleep/exit" ] ; then
        break
    fi
done