Sorry for the late response.
I have created one Java TCP application. To create contact from another application, I just get the needed information like user name, password, extension number,etc..
After receiving those information, I had created one CSV file for that extension and with the help of Process comments I had execute the command. Once the command is executed I just delete the file.
fwconsole bi --type='extensions' extensions.csv
Like the way I am adding extension to FreePBX server. With the help of this command can able to only add the extension. Not able to edit the Extension.
For example, if I alter the password for the extension 105, command shows imported successfully. Its not overwrite the extension 105.
Is there any possible to overwrite the extension ?