Debian based wireless with WPA/WPA2 from CLI

wpa_wlan.sh

#!/bin/bash

# One time only, to create wpa.conf:
# wpa_passphrase ESSID secret > wpa.conf

# su to root, or use sudo for following commands
su

# Bring the wlan interface up
ifconfig wlan0 up

# Start wpa_supplicant. If n180211 driver doesn't
# work for you try the other ones (man wpa_supplicant)
sudo wpa_supplicant -B -Dnl80211 -iwlan0 -c./wpa.conf

# Release old lease just in case (restart dhclient)
dhclient -r

# Obtain new lease
dhclient wlan0