#!/bin/sh

start=2000
end=7000

if [ $# -ne 1 ]
then
        echo "You need to specify the interface \"$0 <iface>\""
        exit 1
fi

if [ x"`which id 2> /dev/null`" != "x" ]
then
        USERID="`id -u 2> /dev/null`"
fi

if [ x$USERID = "x" -a x$UID != "x" ]
then
        USERID=$UID
fi

if [ x$USERID != "x" -a x$USERID != "x0" ]
then
        echo Run it as root ; exit ;
fi

interface=$1

if [ x"`iwconfig "$interface" 2>/dev/null`" = "x" ]
then
        echo "There is no wireless interface \"$interface\"."
        exit 1
fi

i=$start

echo "Available frequencies:"

while [ $i -le $end ]
do
        if [ x"`iwconfig $interface freq "$i"M 2>&1`" = x ]
        then
                echo "$i - $(( (($i - 2412)/5)+1 ))"
        fi
        i=$(($i+1))
done