a bash example on traps, background processes and arrays as function args

bash_trap_multiple.sh

#!/bin/bash
# en: an example of killing background tasks using ctrl+c from bash
#   useful when you need to start/kill a bunch of services
# ru: пример работы с убиваемыми по ctrl-c фоновыми задачами в баш-скрипте
#   полезно, когда надо перезапускать много задач в фоне, например серверов
function ctrl_c() { # trap ctrl-c and call ctrl_c() 
        echo "** Trapped CTRL-C"
        arr=("$@") #take first arg, it's an array
        for i in "${arr[@]}";
        do
          echo "killing ${i}"
          kill $i
        done
}
echo '=> starting first background task [sleep 60 &]'
sleep 60 &  # fake some long running process, could be:  python2 server.py &
TASK1_PID=$! # take a process PID

echo '=> starting second background task [sleep 180 &]'
sleep 180 &
TASK2_PID=$!

echo "=> command1 PID is ${TASK1_PID}"
echo "=> command2 PID is ${TASK2_PID}"

PIDS_TO_KILL=("${TASK1_PID}" "${TASK2_PID}") #make an array of pids

trap 'ctrl_c "${PIDS_TO_KILL[@]}"' INT #set a trap

# trap "ctrl_c 1 " INT #reboot with sudo lol, kills process 1

wait
echo '...done'