#!/bin/sh

export round=0
while [ "$round" -le "50" ]
do
  echo "`date`: Starting round $round"
  export offset=1
  while [ "$offset" -le "5" ]
  do
    octet=`expr $round \* 5`
    octet=`expr $octet + $offset`
    [ "$octet" != "255" ] && \
       nmap -P0 -O 192.168.196.$octet > ${octet}.nmap 2>&1 &
    offset=`expr $offset + 1`
  done
  echo "`date`: Waiting for round $round"
  wait
  round=`expr $round + 1`
done