Just a quicky... :)
To get the wireless interface of your computer, in a simple and "universal" (that works in every system) way, is the following. Just use this simple command:
ls /sys/class/ieee80211/*/device/net/ -1
The command will list the names of the wireless interfaces. If it's only one, you get just that one, so you can simply use it in a command like this:
sudo airmon-ng start $(ls /sys/class/ieee80211/*/device/net/ -1)
In this example, we set the interface in MONITOR mode.