use iw to check wlan device status

$ cat /proc/net/wireless 
Inter-| sta-|   Quality        |   Discarded packets               | Missed | WE
 face | tus | link level noise |  nwid  crypt   frag  retry   misc | beacon | 22
 wlan0: 0000   56.  -54.  -256        0      0      0      0      0        0

OR

$ iw dev wlan0 link
Connected to 00:10:7A:93:AE:BF (on wlan0)
    SSID: SECRETSSID
    freq: 2462
    RX: 89045514 bytes (194863 packets)
    TX: 34783321 bytes (164504 packets)
    signal: -54 dBm
    tx bitrate: 48.0 MBit/s