Stop multiple docker machines

my-docker-machines.sh

#!/bin/sh

machine_names=( $(docker-machine ls | awk '{print $1}') )
echo $1
case "$1" in
    start)
        echo "Starting docker machines $1"
        for (( i=0; i<${#machine_names[@]}; i++ )); do 
            echo ${machine_names[i]}; 
            docker-machine start ${machine_names[i]}
        done
        ;;
    stop)
        for (( i=0; i<${#machine_names[@]}; i++ )); do 
            echo ${machine_names[i]}; 
            docker-machine stop ${machine_names[i]}
        done
        ;;
    restart)
        echo –n “Stopping swarm docker-machines”
        for (( i=0; i<${#machine_names[@]}; i++ )); do 
            echo ${machine_names[i]}; 
            docker-machine stop ${machine_names[i]}
        done
        echo "."
        echo –n "Starting swarm docker-machines"
        for (( i=0; i<${#machine_names[@]}; i++ )); do 
            echo ${machine_names[i]}; 
            docker-machine start ${machine_names[i]}
        done
        echo "."
        ;;
    *)
        echo "Usage: ./my-docker-machines.sh start|stop|restart"
        exit 1
        ;;    
esac