For OS X: show details for all network interfaces

get_interface_data

#!/bin/bash
oldIFS=$IFS
IFS='
'
NETWORKSETUP=$(whereis networksetup)
NETWORKSERVICES=$($NETWORKSETUP -listallnetworkservices | grep -v '^An asterisk')
for service in $NETWORKSERVICES
do
    echo "Service config for $service"
    $NETWORKSETUP -getinfo "$service"
    echo "******"
done
IFS=$oldIFS

Example output:
******
Service config for Display Ethernet
DHCP Configuration
Client ID:
IPv6: Automatic
IPv6 IP address: none
IPv6 Router: none
Ethernet Address: ac:ac:ac:ac:ac:ac
******
Service config for Wi-Fi
DHCP Configuration
IP address: 10.10.10.10
Subnet mask: 255.255.0.0
Router: 10.10.10.254
Client ID:
IPv6: Automatic
IPv6 IP address: none
IPv6 Router: none
Wi-Fi ID: 60:60:60:60:60:60