Bash script - Run commands/jobs in parallel and attach to its output and wait for the return codes sequentially

run_jobs_parallel.sh

# Run job in background, redirect its output to a non-blocking pipe,
# and leave the rc and stdout/stderr to be handled by attach_wait_jobs()
jobs_tmp_dirs=""
function run_job() {
    local dir=$(mktemp -d -t gearXXXXXX)
    jobs_tmp_dirs="$jobs_tmp_dirs $dir"
    mkfifo $dir/pipe
    mkfifo $dir/pipe_nonblock
    "$@" &>$dir/pipe_nonblock &
    echo $! >$dir/pid
    cat $dir/pipe_nonblock | cat >$dir/pipe &
}

# Attach to all jobs being executed by run() one by one in the
# execution order, wait for them to finish and return on error
function attach_wait_jobs() {
    for dir in $jobs_tmp_dirs; do
        cat $dir/pipe
        wait $(<$dir/pid)
        local rc=$?
        [ $rc -eq 0 ] || exit $rc
    done
    cleanup_jobs
}

# Terminate jobs and cleanup temporary files
trap 'cleanup_jobs' EXIT
function cleanup_jobs() {
    local rc=$?
    { pkill -TERM -P $$; } &>/dev/null || :
    for dir in $jobs_tmp_dirs; do
        rm -rf $dir || :
    done
    jobs_tmp_dirs=""
    return $rc
}

# USAGE:
# run_job <command-1> <arguments>
# run_job <command-2> <arguments>
# run_job <command-3> <arguments>
# attach_wait_jobs