cidr converter using sed or awk

Question

I have a text file with IP addresses in cidr format. One cidr per line. How do I convert the cidrs to IP ranges i.e start IP - end IP. One IP range per line. Please note the space on either side of the - .

Answer 1

You'd better use ipcalc:

ipcalc 192.168.0.1/24 -nb | awk '/HostMin/{min=$NF} /HostMax/{max=$NF} END {print min" - "max}'
192.168.0.1 - 192.168.0.254

---

A simple script to loop through the file:

#!/bin/bash

cat file.txt |\
while IFS= read ip; do
    ipcalc "$ip" -nb |\
    awk '   /HostMin/{min=$NF} 
            /HostMax/{max=$NF} 
            END {print min" - "max}'
done