REVEAL THE WIFI PASSWORD ON MAC
Your Mac OS X uses Keychain to store the configuration details of the WiFi network and we can use the BSD command “security” to query anything stored inside Keychain, including the Wi-Fi password. Here’s how:
Open Terminal window. At the command line, enter the following command (replace wifiname with your actual WiFi name), then enter your Mac username and password to access the OS X keychain and the Wi-FI network password would be displayed on the screen in plain text.
security find-generic-password -wa wifiname
REVEAL THE WIFI PASSWORD ON PC
Open the command prompt in administrator mode. Type “cmd” in the Run box, right-click the command prompt icon and choose Run as Administrator. Now enter the following command and hit enter to see the WiFi password.
netsh wlan show profile name=wifiname key=clear | findstr Key
REVEAL THE WIFI PASSWORD ON LINUX
This trick for getting Wi-Fi passwords works for Linux too. Substitute wifiname with the wireless name (SSID) of your network. The value of the field psk is your WiFi password.
sudo cat /etc/NetworkManager/system-connections/wifiname | grep psk=
If you don’t know the network name, use the following command.
sudo grep psk= /etc/NetworkManager/system-connections/