Detect Ethernet, Wireless, Battery, and Main Power Supply, within Linux.

detection.py

#!/usr/bin/env python3
import os

ethernet_interfaces = []
wireless_interfaces = []

def get_interfaces():
    interfaces = os.listdir('/sys/class/net')
    return interfaces

def get_power():
    power_supplies = os.listdir('/sys/class/power_supply')
    return power_supplies

def get_ac(power_supplies):
    for each in power_supplies:
        with open('/sys/class/power_supply/{0}/type'.format(each), 'r') as ac_file:
            for line in ac_file:
                if line.strip() == 'Mains':
                    return each

def get_battery(power_supplies):
    for each in power_supplies:
        with open('/sys/class/power_supply/{0}/type'.format(each), 'r') as ac_file:
            for line in ac_file:
                if line.strip() == 'Battery':
                    return each

def detect_virtual_interfaces(interfaces):
    for each in interfaces:
        real_path = os.path.realpath(os.path.join('/sys/class/net/', each))
        if '/devices/virtual/net/' in real_path:
            interfaces.remove(each)
    return interfaces

def detect_ethernet(clean_interfaces):
    for each in clean_interfaces:
        try:
            with open('/sys/class/net/{0}/speed'.format(each), 'r') as speed_file:
                for line in speed_file:
                    ethernet_interfaces.append(each)
        except OSError:
            pass

def detect_wireless(clean_interfaces):
    for each in clean_interfaces:
        if os.path.isdir('/sys/class/net/{0}/wireless'.format(each)):
            wireless_interfaces.append(each)


if __name__ == '__main__':
    interfaces = get_interfaces()

    clean_interfaces = detect_virtual_interfaces(interfaces)

    detect_ethernet(clean_interfaces)
    if not ethernet_interfaces:
        print('No ethernet detected!')
    else:
        print('Ethernet:', ', '.join(ethernet_interfaces))

    detect_wireless(clean_interfaces)
    if not wireless_interfaces:
        print('No wireless detected!')
    else:
        print('Wireless:', ', '.join(wireless_interfaces))

    power_supplies = get_power()

    main_power_supply = get_ac(power_supplies)
    battery = get_battery(power_supplies)

    if not main_power_supply and battery:
        print('Battery: {0}'.format(battery))
    elif main_power_supply and battery:
        print('Power Supply: {0}'.format(main_power_supply))
        print('Battery: {0}'.format(battery))
    elif main_power_supply and not battery:
        print('Power Supply: {0}'.format(main_power_supply))
    elif not main_power_supply and not battery:
        print('This shouldn\'t happen.')
        print('No power supply detected, no battery detected.')