ifconfig <wlan_device> up
iw <wlan_device> scan
wpa_passphrase <ESSID> > /etc/_some_wifi_conf_file
wpa_suppplicant -B -i <wlan_dev> -c /etc/_some_wifi_conf_file
-B: background
-i: WLAN interface
-c: config file
iw <wlan_device> link
dhclient <WLAN_device>