Bash script to use and monitor wifi hotspot connections on linux systems

monitor.sh

#!/usr/bin/env bash
    
# how_wifi_clients.sh
# Shows MAC, IP address and any hostname info for all connected wifi devices
# written for openwrt 12.09 Attitude Adjustment
# modified by [email protected] from http://wiki.openwrt.org/doc/faq/faq.wireless#how.to.get.a.list.of.connected.clients

function mon () {

  echo    "# All connected wifi devices, with IP address,"
  echo    "# hostname (if available), and MAC address."
  printf  "# %-20s %-30s %-20s\n" "IP address" "lease name" "MAC address"
  leasefile=/var/lib/misc/dnsmasq.leases
  # list all wireless network interfaces 
  # (for MAC80211 driver; see wiki article for alternative commands)
  for interface in `iw dev | grep Interface | cut -f 2 -s -d" "`
  do
    # for each interface, get mac addresses of connected stations/clients
    maclist=`iw dev $interface station dump | grep Station | cut -f 2 -s -d" "`
    # for each mac address in that list...
    for mac in $maclist
    do
    # If a DHCP lease has been given out by dnsmasq,
    # save it.
       ip="UNKN"
       host=""
       ip=`cat $leasefile | cut -f 2,3,4 -s -d" " | grep $mac | cut -f 2 -s -d" "`
       host=`cat $leasefile | cut -f 2,3,4 -s -d" " | grep $mac | cut -f 3 -s -d" "`
       # ... show the mac address:
       printf "  %-20s %-30s %-20s\n" $ip $host $mac
    done
  done

}

export -f mon
watch -x bash -c mon

Wow