#!/bin/sh
# Asuming you want to make a random private /120 prefix in IPv6 and have all of those addresses assigned to the loopback interface (dev lo), and you're root, and have https://gitlab.com/ipcalc/ipcalc installed, run:
eval "$(ipcalc -r 120 -np)"
netpref="${NETWORK}/${PREFIX}"
ip addr add "$netpref" dev lo scope host
ip route add local "$netpref" dev lo