iw dev wlan0 station dump
This is very useful because it is helpful if you are running something like hostapd and need to see the signal strength and negotiated connection speed.
Station ff:ff:ff:ff:ff:ff (on wlan0)
inactive time: 16309 ms
rx bytes: 25451
rx packets: 325
tx bytes: 44381
tx packets: 159
tx retries: 0
tx failed: 0
signal: -72 [-72] dBm
signal avg: -72 [-72] dBm........