#!/bin/bash
ipAndIptoNetwork()
{
  echo "test"
  # expects $1 to be an ip address
  # expects $2 to be an ip address
  local oldifs
  local IP1
  local IP2
  local ip1num
  local ip2num
  local masknum
  local t
  local ipnet
  local prefix
  local ipnetnum
  echo "blah"
  oldifs="$IFS"
  IFS=.
  IP1=($1)
  IP2=($2)
  ip1num=$((IP1[0]*256*256*256 + IP1[1]*256*256 + IP1[2]*256 + IP1[3]))
  ip2num=$((IP2[0]*256*256*256 + IP2[1]*256*256 + IP2[2]*256 + IP2[3]))
  masknum=$((255*256*256*256 + 255*256*256*256 + 255*256 + 255))
  IFS="$oldifs"
  ((masknum= !(ip2num-ip1num) ))
  echo $masknum
  echo $ip1num
  echo $ip2num
  ((ipnetnum= ip1num & masknum))
  ((t=masknum))
  for ((prefix=32; (t & 1) == 0; t /= 2))
  do
    ((prefix--))
  done
  ipnet=($ipnetnum)
  ipnet=$((ipnet >> 24)).$(((ipnet >> 16) & 255)).$(((ipnet >> 8) & 255)).$((ipnet & 255))/$prefix
  echo $ipnet
}
echo "will hang on the next line"
echo "`ipAndIptoNetwork "192.168.1.0" "192.168.1.255"`"