To build a wpa_supplicant configuration file:
# wpa_passphrase testap >> /etc/wpa_supplicant/testap.conf
a_password
# cat /etc/wpa_supplicant/testap.conf
# reading passphrase from stdin
network={
ssid="testap"
#psk="a_password"
psk=1b97a5c02076ac80739263fb33db49c7c50d3199202872e06097e7baf305f35e
}
Additional info at How to connect to a WPA/WPA2 WiFi network using Linux command line.
