Shell Script - os.sh

This is a script that will ATTEMPT to identify what operating systems are running on a network. I made it so it will output to the screen and to a file. So far it has been somewhat successful in identifying operating systems. I give no guarantee that it will get -every- o.s. on your network.

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os.sh

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#! /bin/bash

clear
echo "------------------------------------------------------------"
echo "This Will ATTEMPT To Identify Operating Systems On A Network"
echo "Just FYI... You Probably Need To Run This As ROOT"
echo "------------------------------------------------------------"
sleep 5
clear

echo "------------------------------------------"
echo "Output Will Go To 'os.sh.txt' & The Screen"
echo "------------------------------------------"
echo "Results Start From : `date`" > os.sh.txt
echo "----------------------------------------------------------------------------" >> os.sh.txt
sleep 3
clear

echo "-----------------------------"
echo "Enter First 3 Octets (x.x.x):"
read ipthree
echo "-----------------------------"
echo "Enter 4th Octet FIRST IP:"
read ipfirst
echo "-----------------------------"
echo "Enter 4th Octet ENDING IP:"
read iplast
echo "-----------------------------"
sleep 1
clear

iprange=`echo $ipthree | cut -d. -f1-3`
# Use If First IP Range Is Giving Trouble - CAUTION, May Give Unwanted Results If 'ipthree' Is Fatfingered
#iprange=`echo $ipthree`

for (( i = $ipfirst ; i <= $iplast ; i++ ))
do
nmaplist=`nmap -P0 -O $iprange.$i | grep Running`
nmapcut=`echo $nmaplist | cut -c1-3`

if [ $nmapcut = Run ]
then
echo "$iprange.$i :$nmaplist" >> os.sh.txt
clear
cat os.sh.txt
else
clear
cat os.sh.txt
fi

done

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