auto start ngrokd script on centos, put this script to /etc/init.d/ngrokd

ngrokd.sh

#!/usr/bin/env bash
# These setting need you to set.
LOCATION=/usr/local/src/ngrok/bin
TLSKEY=/usr/local/src/ngrok/bin/device.key
TLSCRT=/usr/local/src/ngrok/bin/device.crt
DOMAIN=ngrok.domain.com
PORT=8000
HTTPSPORT=4443
LOGFILE=/usr/local/src/ngrok/bin/logs/ngrokd.log
PIDFILE=/usr/local/src/ngrok/bin/run/ngrokd.pid
NAME=ngrokd

# you should use /lib/init.d/functions in centos
#. /lib/lsb/init-functions
. /etc/init.d/functions

do_start()
{
    if [ -s $PIDFILE ]; then
        RETVAL=1
        echo "$NAME already running!"
    else
        echo "starting $NAME"
        nohup $LOCATION/$NAME -domain="$DOMAIN" -httpAddr=":$PORT" -log=$LOGFILE -log-level=INFO >/dev/null 2>&1 &
        RETVAL="$?"
        PID="$!"
        echo $PID
        if [ "$RETVAL" = "0" ]; then
            echo $PID > $PIDFILE
            chmod 755 $LOGFILE
            echo "$NAME started."
            return $RETVAL       
        else
            echo "start $NAME failed!"
            return $RETVAL
        fi
    fi
}

do_stop()
{
    killproc -p $PIDFILE $LOCATION/$NAME
    RETVAL="$?"
    if [ "$RETVAL" = "0" ]; then        
        rm -rf $PIDFILE
        echo "stop $NAME successfully."
    else
        echo "stop $NAME failed!"
    fi
    return $RETVAL
}

case "$1" in
  start)
    do_start
    ;;

  stop)
    echo "stopping $NAME"
    do_stop
    ;;

  status)
    if [ ! -s $PIDFILE ]; then
        echo "$NAME is not running."
    else
        PID=`cat $PIDFILE`
        if [[ -n $PID && -n "`ps -p $PID | grep $PID`" ]]; then
            echo "$NAME is running (${PID})"
        else
            echo "$NAME is not running, yet ${PIDFILE} exists (stop ngrokd will fix this)"
        fi
    fi
    ;;

  *)
    echo "Usage: ngrokd (start|stop|status)"
    exit 3
    ;;
esac

exit 0