Bash process control

child.sh

#!/usr/bin/env bash
set -euo pipefail
IFS=$'\n\t'
DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"

source /tmp/x

function handler() { 
	d "    child: caught SIGTERM signal, exiting" 
	exit 0
}
trap handler SIGTERM

d "    child: start $$"
for N in $(seq 1 5); do
	d "child: $N"
	sleep 30 &
	wait $!
done
d "    child: done"

run.sh

#!/usr/bin/env bash
set -euo pipefail
IFS=$'\n\t'
DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"

source /tmp/x

bash /tmp/sig.sh &
PID="$!"
d "master start"

sleep 1
d "master: sending SIGTERM to $PID"
kill -s TERM $PID
wait "$PID"

sig.sh

#!/usr/bin/env bash
set -euo pipefail
IFS=$'\n\t'
DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"

source /tmp/x

child=0

function handler() { 
	d a"  sig: caught SIGTERM signal"
	d a"  sig: forwarding SIGTERM to $child"
	kill -s TERM "$child"
	d a"  sig: waiting for process $child"
	wait "$child"
	d a"  sig: process $child exited, exiting this wrapper"
	exit 0
}
trap handler SIGTERM

d a"  sig: start $$"
while true; do
	bash /tmp/child.sh &
	child=$!
	wait $child
	sleep 10
done

x

function d() {
	NOW="$(php -r 'echo microtime(TRUE);')"
	echo "$NOW $@"
}

Usage:

bash run.sh

Example output:

1518116990.5304 master start
1518116990.5304   sig: start 34887
1518116990.6124     child: start 34893
1518116990.6915 child: 1
1518116991.6045 master: sending SIGTERM to 34887
1518116991.6837   sig: caught SIGTERM signal
1518116991.7661   sig: forwarding SIGTERM to 34893
1518116991.8395   sig: waiting for process 34893
1518116991.8395     child: caught SIGTERM signal, exiting
1518116991.9175   sig: process 34893 exited, exiting this wrapper