Query gateway router for public IP address

#!/bin/bash
# Author: Frash Pikass
# Dependencies: expect

if [ "$#" -eq "3" ]
then
    (expect <<-finish
    #If it all goes pear shaped the script will timeout after 20 seconds.
    set timeout 20
    spawn telnet $1

    #The script expects login
    expect "login:"
    #The script sends the user variable
    send "$2\r"
    #The script expects Password
    expect "Password:"
    #The script sends the password variable
    send "$3\r"
    expect "#"
    send "ifconfig ppp0\r"
    expect "#"
    close

    finish
    ) | grep -o  'addr:[^ ]*' | sed s/addr://

    exit 0

else
    echo "Usage: $0 gatewayRouterIP routerAdminUsername routerAdminPassword"
    exit 1
fi