On Linux: how can I programmatically determine if a NIC interface is enabled and plugged in?

Question

I want to determine if a network card is enabled, up, and plugged in. Basically, I want to know if the network card will work. I need this information from with a C++ program, a

Answer 1

Run through the output of getifaddrs, you can use the link layer for the MAC address to identify an adapter and check the ifa_flags for IFF_UP. Use AF_NETLINK for notifications about interface changes.