Graceful termination of child in systemctl shutdown

Question

I liked SensorSmith answer at Forward SIGTERM to child in Bash, but for my systemctl script, it resulted in a double SIGTERM, because systemctl sends SIGTERM to the parent bash instance AND the child I am running. The result was instant termination before my child could gracefully shut down.

What's the proper way to handle SIGTERM in a bash script based service?

Answer 1

So I ended up with this and I am happy:

#!/bin/bash

script_term()
{
    echo $0 SIGTERM
}

wait_for_child()
{
    term_child_pid=$!
    wait ${term_child_pid} 2>/dev/null
    trap - TERM INT
    wait ${term_child_pid} 2>/dev/null
}

trap 'script_term' TERM INT
node index.js
wait_for_child

It waits properly in all the cases I care about, though it does not SIGTERM the child when the parent bash is SIGTERM'd.