Two commands to get your current WiFi password or any WiFi password stored in your macOS keychain!

get_stored_airport_wifi_passwords.js

#!/bin/bash

get_current_wifi_password() {
  # this command from http://bit.ly/2zWtUhQ
  current_wifi=`/System/Library/PrivateFrameworks/Apple80211.framework/Versions/Current/Resources/airport -I | \
  awk '/ SSID/ {print substr($0, index($0, $2))}'`  
  security find-generic-password -a "$current_wifi" -g | tail -0
}

get_wifi_password() {
  security find-generic-password -a "$1" -g | tail -0
}