Connect to a Wi-Fi Network from a QR Code
It’s possible to encode the details of a Wi-Fi network in a QR code. Visitors can scan the QR code to easily connect to your guest Wi-Fi.
The keyword is WIFI, followed by a colon ” : ” and several other parameters.
T: The type of security. This can be WEP, WPA, or WPA2. Note there is a colon between the “T” and the security value, and there is a semicolon ” ; ” after the security setting. S: The Service Set ID (SSID) of the Wi-Fi network. Note there is a colon between the “S” and the SSID, and there is a semicolon ” ; ” after the SSID. P: The password or security key of the Wi-Fi network. Note there is a colon between the “P” and the security key, and are two semicolons ” ;; ” after the security key.
qrencode -s 6 -l H -o "wifi.png" "WIFI:T:WPA;S:<SSID>;P:<PSWD>;;"
https://www.cloudsavvyit.com/8382/how-to-create-qr-codes-from-the-linux-command-line/