How to wait in bash for several subprocesses to finish and return exit code !=0 when any subprocess ends with code !=0?

Question

How to wait in a bash script for several subprocesses spawned from that script to finish and return exit code !=0 when any of the subprocesses ends with code !=0 ?

S

Answer 1

#!/bin/bash
set -m
for i in `seq 0 9`; do
  doCalculations $i &
done
while fg; do true; done

• set -m allows you to use fg & bg in a script
• fg, in addition to putting the last process in the foreground, has the same exit status as the process it foregrounds
• while fg will stop looping when any fg exits with a non-zero exit status

unfortunately this won't handle the case when a process in the background exits with a non-zero exit status. (the loop won't terminate immediately. it will wait for the previous processes to complete.)