GPT on Question 14, Sep 22

In Bash, the idiomatic approach is to trap script termination, kill tracked children, and then reap them:

#!/usr/bin/env bash

children=()

cleanup() {
    trap - EXIT INT TERM HUP

    if ((${#children[@]})); then
        kill "${children[@]}" 2>/dev/null || :
        wait "${children[@]}" 2>/dev/null || :
    fi
}

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

some_command &
children+=("$!")

another_command &
children+=("$!")

wait

Important limitations:

• •EXIT traps do not run after SIGKILL, a kernel crash, or abrupt power loss.
• •This kills only the recorded direct children, not arbitrary grandchildren.
• •Avoid kill 0 unless the script runs in its own process group; otherwise it may kill the invoking shell or unrelated processes.

For reliable cleanup of an entire process tree, use an external supervisor or containment mechanism:

• •A systemd service with KillMode=control-group
• •A dedicated cgroup/container
• •On Linux, a child wrapper using prctl(PR_SET_PDEATHSIG, SIGTERM)
• •A dedicated process group/session, killed as a group

Once the parent is already dead, Bash itself cannot perform cleanup; orphaned processes are reparented. Cleanup must therefore be arranged beforehand or handled by a supervisor.