get-ip.sh

#!/bin/bash

# Try to get IPv4 address and mask from tun0
tun_info=$(ip -4 addr show tun0 2>/dev/null | grep -oP 'inet \K[\d.]+/\d+')

# Try to get IPv4 address and mask from eth0 if tun0 fails
eth_info=$(ip -4 addr show eth0 2>/dev/null | grep -oP 'inet \K[\d.]+/\d+')

# Decide which to display
if [[ -n "$tun_info" ]]; then
    echo "$tun_info [tun0]"
elif [[ -n "$eth_info" ]]; then
    echo "$eth_info [eth0]"
else
    echo "No IP address found for tun0 or eth0" >&2
    exit 1
fi