Wordpress, create json file when a term is updated/deleted/created - wordpress

Question

I have to create a json file when a term is created/updated/deleted from a taxonomy "product_cat", below i attempt to register a simple json file but without success :
add_action( 'create_term', 'wpse_create_term', 10, 3 );
add_action( 'created_term', 'wpse_created_term', 10, 3 );
add_action( 'edited_term', 'wpse_edited_term', 10, 3 );
add_action( 'delete_term', 'wpse_delete_term', 10, 5 );
function wpse_create_term(){
createJsonFile();
}
function wpse_created_term(){
createJsonFile();
}
function wpse_edited_term(){
createJsonFile();
}
function wpse_delete_term(){
createJsonFile();
}
function createJsonFile(){
echo "begin write to json file to " . dirname(__FILE__);
$data = array("a","b","c","d");
//format the data
$formattedData = json_encode($data);
//set the filename
$filename = 'members.json';
//open or create the file
$handle = fopen($filename,'w+');
//write the data into the file
fwrite($handle,$formattedData);
//close the file
fclose($handle);
}
Firstly, why those hooks never fired ( the echo is not printed when updating a term ) ? and how should i specify destination folder for the final json file?
Thanks for your help.

Answer 1

You cant echo something from the function file you might want to use the debug.log for it
Secondly you need to specify a location where to create the json file