How do I execute multiple commands in parallel on an array of parameters with bash, and fail if at least one of them failed
You are so close to getting the syntax of GNU Parallel correct:
COMMAND=echo
PARAMETERS=(first-parameter second-parameter third-parameter)
parallel -j 4 -k --retries 2 "$COMMAND" {} ::: "${PARAMETERS[@]}" ||
echo $? commands failed. More than 99 if $? = 100
Or if you really insist on doing the retrying yourself:
PARAMETERS=(first-parameter second-parameter third-parameter)
export -f run_and_retry
parallel -j 4 -k run_and_retry {} ::: "${PARAMETERS[@]}" ||
echo One or more commands failed
I need to know if at least one of the executions failed (returned non-zero)
From posix xargs:
EXIT STATUS
1-125
A command line meeting the specified requirements could not be assembled, one or more of the invocations of utility returned a non-zero exit status, or some other error occurred.
The man xargs seems a bit different:
EXIT STATUS
123 if any invocation of the command exited with status 1-125
But I would check the return status of the command and return a predefined number (ex. 1) from the function to handle that.
parameters=(1 2 3 fail)
func() {
COMMAND=sleep
# I guess OP intends to try running COMMAND twice
if ! "$COMMAND" 0."$1" && ! "$COMMAND" 0."$1"; then
return 1
fi
}
export -f func
if printf "%s\0" "${parameters[@]}" | xargs -0 -P4 -n1 -t -- bash -c 'func $1' -- ; then
echo "Success!"
else
echo "Error!"
fi
Live version available at tutorialspoint.
Well, we can even count the number of childs manually, and it get's pretty simple with wait -n
. From stackoverflow - WAIT for “1 of many process” to finish:
bash 4.3 added a -n flag to the built-in wait command, which causes the script to wait for the next child to complete.
So we can just:
cnt=0
failed=false
for i in "${parameters[@]}"; do
( func "$i" ) &
if (( cnt < 4 )); then
cnt=$((cnt+1))
else
# handle more then 4 processes
if ! wait -n; then
failed=true
fi
fi
done
# handle still running processes after all have been forked
for i in $(seq $cnt); do
if ! wait -n; then
failed=true
fi
done
if "$failed"; then
echo "One of the jobs failed!"
fi