Wifi scan and connect script

There are multiple USB wifi cards connected to a single laptop (via powered hub) Card 0 is reserved for ad hoc connections and is already working fine The rest of the cards need to scan area frequently and connect to wifi networks found There will be a file in which I can list the preferred networks with their key. (wep/wpa etc) Every X minutes system will scan surrounding area If some preferred network is found then connect to them using available cards. in order of card number eg wlan1, then wlan2 then wlan3 etc Preferred network file must be read top down for priority. So if 5 cards are available and 3 preferred networks are found then card 1 will connect to first preferred network, card 2 to second etc. . Do one connection every X minutes and make that the default route After all preferred network have been connected to and connection works, ie can do nslookup connect to open networks with strongest network as highest priority. DO ONE NEW CONNECTION EVERY X MINUTES and make that one the default route When a connected network is no longer in sight or can not do nslookup ( check every y min) make the wifi card available. Connect to new networks when seen. every time a new network is connected to. Make that the default route. Ensure that 1 network is connected to 1 wifi card max. Do NOT move connection from 1 wifi card to another card just because signal strength has changed. Card is already working