Turns wireless monitor mode on/off

monitor-mode.sh

if [ $# -ne 2 ]; then
    echo "usage: ./monitor-mode.sh INTERFACE [on|off]"
    exit 1
fi

# if interface not exists
sudo iw dev $1 info > /dev/null 2>&1
if [ $? -ne 0 ]; then
    echo "unable to find device '$1'"
    exit 2
fi

# if option is not on/off
if [ $2 != "on" ] && [ $2 != "off" ]; then
    echo "expected either 'on' or 'off', got: '$2'"
    exit 3
fi


sudo ip link set dev $1 down
if [ $2 = "on" ]; then
    echo "Warning: this script stops NetworkManager"
    sudo iwconfig $1 mode monitor
    sudo service NetworkManager stop
elif [ $2 = "off" ]; then
    sudo iwconfig $1 mode managed
    sudo service NetworkManager start
fi
sudo ip link set dev $1 up