The steps are:
1- Burn a standard SD image
2- Run a standard SD image (it will create wpa_supplicant.conf file in /data folder)
3- Symplink /data/wpa_supplicant to boot/wifi.conf with the following lines (always with -rw in ssh or linux console)
sudo mv /home/pi/data/wpa_supplicant.conf /boot/wifi.conf
sudo ln -s /boot/wifi.conf /home/pi/data/wpa_supplicant.conf
4- Switch off (sudo shutdown now)
5- Save the “WIFI.CONF image” to have this to copy to other SD
6- Introduce “WIFI CONF image SD” in windows, Linux or Mac and change wifi.conf with Notepad++. Use Notepad++ to not change the format of .conf file.
network={
ssid= “networkSSID”
psk=“password”
}
7- Introduce SD in the favourite Raspberry Pi with WIFI device and … HURRAY!!!
Thanks Paul and Glyn for your amazing support.