Q:

Where ifconfig informations are stored?

Where are saved the information given by ifconfig command on raspbian?
I need to read these informations from a file.
Is there any file where (as an example) the mac address of an interface is stored?

A:

Raspbian is a Linux based operating system and in Linux most information like the information provided by the ifconfig command is available in a special file.  From this Superuser answer the MAC address is available by reading /sys/class/net/$iFACE/address where $iFACE is a shell variable that contains the interface name desired.  Or just by explicitly reading file /sys/class/net/eth0/addresss for interface eth0.
raspberrypi ~ $ cat /sys/class/net/eth0/address
b8:27:eb:a3:f9:94

