Wi-Fi channel hopper

chanhopper.sh

#!/bin/bash

msg() {
    printf -- '%s\n' "$@"
}

err() {
    printf -- 'error: %s\n' "$@" >&2
    exit 1
}

usage() {
    cat <<EOF
usage: ${0##*/} -i <wireless interface> [-v] [-h]

options
    -i    specify wireless interface name
    -v    enable verbose mode
    -h    show help
EOF
}

if [[ $# -lt 1 ]]; then
    usage
    exit 1
fi

if [[ $EUID -ne 0 ]]; then
    err 'insufficient permisions'
fi

if ! command -v iwlist &> /dev/null; then
    err "iwlist: command not found"
fi

while getopts :i:vh arg; do
    case $arg in
        i) interface=$OPTARG ;;
        v) verbose=1 ;;
        h) usage; exit ;;
        *) usage; exit 1 ;;
    esac
done

# Get list of supported channels
channels=$(iwlist "$interface" freq | awk '/ Channel/ {printf "%s ", $2}')

if [[ $channels ]]; then
    [[ $verbose ]] && msg "supported channels on $interface: $channels"

    while :; do
        for chan in $channels; do
            iwconfig "$interface" channel "$chan" || err "$interface: error while hopping to channel $chan"
            [[ $verbose ]] && msg "current channel on $interface: $chan"
            sleep .10
        done
    done
else
    err "$interface: failed to get supported channels"
fi