$ networksetup -listallnetworkservices
An asterisk (*) denotes that a network service is disabled.
Ethernet
FireWire
Wi-Fi

$ networksetup -listnetworkserviceorder
An asterisk (*) denotes that a network service is disabled.
(1) Ethernet
(Hardware Port: Ethernet, Device: en0)

(2) FireWire
(Hardware Port: FireWire, Device: fw0)

(3) Wi-Fi
(Hardware Port: Wi-Fi, Device: en1)

ifconfig

#!/bin/bash

services=$(networksetup -listnetworkserviceorder | grep 'Hardware Port')

while read line; do
    sname=$(echo $line | awk -F  "(, )|(: )|[)]" '{print $2}')
    sdev=$(echo $line | awk -F  "(, )|(: )|[)]" '{print $4}')
    #echo "Current service: $sname, $sdev, $currentservice"
    if [ -n "$sdev" ]; then
        ifout="$(ifconfig $sdev 2>/dev/null)"
        echo "$ifout" | grep 'status: active' > /dev/null 2>&1
        rc="$?"
        if [ "$rc" -eq 0 ]; then
            currentservice="$sname"
            currentdevice="$sdev"
            currentmac=$(echo "$ifout" | awk '/ether/{print $2}')
        fi
    fi
done <<< "$(echo "$services")"

if [ -n "$currentservice" ]; then
    echo $currentservice
    echo $currentdevice
    echo $currentmac
else
    >&2 echo "Could not find current service"
    exit 1
fi

$ sh networkservice.sh
Wi-Fi
en0
78:31:c1:c2:d7:6c

$ route get example.com | grep interface
interface: en8

$ networksetup -listnetworkserviceorder | grep en8
(Hardware Port: Broadcom NetXtreme Gigabit Ethernet Controller, Device: en8)

set public (dig +short myip.opendns.com @resolver1.opendns.com)

defaults read /Library/Preferences/SystemConfiguration/com.apple.airport.preferences |grep LastConnected -A 7

function netinfo -d "get network information"

  # Get public ip address
  set public (dig +short myip.opendns.com @resolver1.opendns.com)
  set hostname (uname -n)

  if test -z "$public" # We got an empty string, meaning:
    set public "No Internet connection available"
  end

  echo ''
  echo "    Public IP: $public"
  echo "     Hostname: $hostname"
  echo ''

  # Get all available hardware ports
  set ports (ifconfig -uv | grep '^[a-z0-9]' | awk -F : '{print $1}')

  # Get for all available hardware ports their status
  for val in $ports
    set activated (ifconfig -uv $val | grep 'status: ' | awk '{print $2}')

    # We want information about active network ports...
    if test $activated = 'active' ^/dev/null
      set ipaddress (ifconfig -uv $val | grep 'inet ' | awk '{print $2}')

      # and of these, the ones with an IP-address assigned to it
      if test -n "$ipaddress" ^/dev/null

        # Do we have an IP address?
        # Then give us the information
        set label (ifconfig -uv $val | grep 'type' | awk '{print $2}')
        set macaddress (ifconfig -uv $val | grep 'ether ' | awk '{print $2}')
        set quality (ifconfig -uv $val | grep 'link quality:' | awk '{print $3, $4}')
        set netmask (ipconfig getpacket $val | grep 'subnet_mask (ip):' | awk '{print $3}')
        set router (ipconfig getpacket $val | grep 'router (ip_mult):' | sed 's/.*router (ip_mult): {([^}]*)}.*/1/')
        set dnsserver (ipconfig getpacket $val | grep 'domain_name_server (ip_mult):' | sed 's/.*domain_name_server (ip_mult): {([^}]*)}.*/1/')

        # Header for the network interfaces
        echo -n $label ; echo -n ' ('; echo -n $val ; echo ')'
        echo "--------------"

        # Is this a WiFi associated port? If so, then we want the network name
        switch $label
          case Wi-Fi
            # Get WiFi network name
            set wifi_name (/System/Library/PrivateFrameworks/Apple80211.framework/Versions/A/Resources/airport -I | grep 'sSSID:' | sed 's/.*: //')
            echo " Network Name: $wifi_name"
            # Networkspeed for Wi-Fi
            set networkspeed (/System/Library/PrivateFrameworks/Apple80211.framework/Versions/A/Resources/airport -I | grep lastTxRate: | sed 's/.*: //' | sed 's/$/ Mbps/')
          case '*'
            # Networkspeed  for other ports
            set networkspeed (ifconfig -uv $val | grep 'link rate:' | awk '{print $3, $4}')
        end

        echo "   IP-address: $ipaddress"
        echo "  Subnet Mask: $netmask"
        echo "       Router: $router"
        echo "   DNS Server: $dnsserver"
        echo "  MAC-address: $macaddress"
        echo "Network Speed: $networkspeed"
        echo " Link quality: $quality"
        echo ''
      end

      # Don't display the inactive ports.
    else if test $activated = 'inactive' ^/dev/null
    end
  end
end