Pause/resume/stop process control in bash.

_ctl.sh

#!/usr/bin/env bash

TASK=$@

FAIL_CNT=0
RUN=
TASK_PID=
LOOPID=1

_ctl() {
    if [[ "${RUN}" = "${1}" ]]; then
        return
    fi
    RUN=$1
    LOOPID=$((${LOOPID} + 1))
    if [[ "${TASK_PID}" != "" ]]; then
        kill ${TASK_PID}
        wait ${TASK_PID}
        TASK_PID=
    fi
    if [[ "${RUN}" = "true" ]]; then
        _work ${LOOPID}
        return
    fi
    if [[ "${RUN}" = "false" ]]; then
        echo "Termination signal received, exiting."
    fi
    while [[ ${RUN} = "stop" ]]; do
        sleep 1
    done
}

_work() {
    while [[ "${LOOPID}" = "$1" ]]; do
        ${TASK} &
        TASK_PID=$!
        echo "Process PID: ${TASK_PID}"
        wait ${TASK_PID}
        TASK_EXIT_CODE=$?
        echo "Task exited with ${TASK_EXIT_CODE}"
        if [[ "${TASK_EXIT_CODE}" = "0" ]] || [[ "${TASK_EXIT_CODE}" = "130" ]]; then
            FAIL_CNT=0
        else
            FAIL_CNT=$((${FAIL_CNT} + 1))
            printf '\033[31m%s\033[0m\n' "ACHTUNG!!! Task failed ${FAIL_CNT} times! Waiting $((2**$FAIL_CNT)) sec."
            sleep $((2**${FAIL_CNT}))
        fi
    done
}

echo "PID: $$"

trap "_ctl 'false'" SIGINT SIGTERM
trap "_ctl 'stop'" SIGTSTP
trap "_ctl 'true'" SIGCONT

_ctl 'stop'