exec - execute PHP script and get an update of process -

i need write script in php read list of xml , convert them in text file

i add button in page triggers

exec("xml2csv.php"); 

since can have lot of them give user feedback on process update, can text feedback

kind of javascript image upload % update

i'm not sure possible , how proceed

provided know number of lines or bytes of xml must parse, have php script write file on server number of bytes (or lines) has completed writing periodically throughout scripts execution using file_put_contents().

on client side, using ajax, poll server contents of file , display result user every x seconds. using jquery's $.post this.