You may be interested in jq:
> jq is like sed for JSON data - you can use it to slice and filter and map and transform structured data with the same ease that sed, awk, grep and friends let you play with text.
> jq is like sed for JSON data - you can use it to slice and filter and map and transform structured data with the same ease that sed, awk, grep and friends let you play with text.
curl -s https://ip-ranges.amazonaws.com/ip-ranges.json | jq '.prefixes | .[].ip_prefix | .[-3:]' | sort | uniq -cNetmasks might not always be three characters.
Perhaps something like this:
curl -sf https://ip-ranges.amazonaws.com/ip-ranges.json | jq -r '.prefixes[].ip_prefix' | grep -o '/.*' | sort | uniq -c
curl -sf https://ip-ranges.amazonaws.com/ip-ranges.json | jq 'reduce (.prefixes[].ip_prefix | split("/")[1]) as $mask ({}; .[$mask] += 1)'