#!/bin/sh
set -o errexit

is_phys() {
	test -d "/sys/class/net/${1}/device"
}

interface_type() {
	if is_phys "$1"; then
		printf 'phys'
	else
		printf 'virt'
	fi
}

list_interfaces() {
	for interface in /sys/class/net/*; do
		printf '%s\n' "$(basename "$interface")"
	done
}

while read -r interface; do
	printf '%s: %s\n' \
		"$(interface_type "$interface")" \
		"$interface"
done << EOF
$(list_interfaces)
EOF