GPT on Question 14, Sep 23

Bash does not automatically kill children when it exits. The usual pattern is to track child PIDs and clean them up with an EXIT trap:

#!/usr/bin/env bash
set -uo pipefail

children=()

cleanup() {
    rc=$?
    trap - EXIT HUP INT TERM

    if ((${#children[@]})); then
        kill -TERM "${children[@]}" 2>/dev/null || true
        sleep 1
        kill -KILL "${children[@]}" 2>/dev/null || true
        wait "${children[@]}" 2>/dev/null || true
    fi

    exit "$rc"
}

trap cleanup EXIT
trap 'exit 129' HUP
trap 'exit 130' INT
trap 'exit 143' TERM

worker_a &
children+=("$!")

worker_b &
children+=("$!")

wait

Important limitations:

• •Traps do not run after SIGKILL, machine failure, or some abrupt shell failures.
• •This kills only the recorded processes, not necessarily grandchildren that daemonize or otherwise detach.
• •Avoid kill 0 or kill -- -$$ unless the script was deliberately placed in its own process group; otherwise you may kill the invoking shell too.

If cleanup must also work when the parent is killed with SIGKILL, use an external supervisor, such as a systemd service with KillMode=control-group, or run the workload in a dedicated process group/cgroup. On Linux, a small wrapper using prctl(PR_SET_PDEATHSIG, ...) is another option, but Bash itself cannot set that reliably.