IP script assist

[DeadBeet]

So, I'm trying to build a script for my place of employment. I'm building it in pieces. Right now, I've been stuck on a piece for a bit, getting closer and closer to the end by guess and check. But now, I have no clue where to start this next one.

I'm trying to make it so the user inputs the CIDR and it calculates the gateway, and first and last usable IP. Right now, it only works for a /29. I'm trying to make it so it creates multiple virtual IPs. so ifcfg-eth1:1 1:2 1:3 etc. Until it gets to the last IP. Right now, I have:

#!/bin/bash

echo -n "Enter IP: "
read IP;
num=1

echo Gateway: "$IP" | awk -F "." '{print $1 "." $2 "." $3 "." ($4+1);}'
echo First Usable IP: "$IP" | awk -F "." '{print $1 "." $2 "." $3 "." ($4+2);}'
echo Last Usable IP: "$IP" | awk -F "." '{print $1 "." $2 "." $3 "." ($4+7);}'

echo > echotest
echo GATEWAY="$IP" | awk -F "." '{print $1 "." $2 "." $3 "." ($4+1)}' >> echotest
echo IPADDR="$IP" | awk -F "." '{print $1 "." $2 "." $3 "." ($4+2+$num)}' >> ./echotest


This just calculates the gateway and first and last and echos the first usable IP and the gateway into a file called echotest. How do I get it to keep creating the files until it hits the last usable IP?

Thanks!!

[nmset]

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