php function of ignore_user_abort that can continue to execute after the browser is closed

 
ignore_user_abort(true); // Sets whether to interrupt script execution when the client disconnects  
set_time_limit(0); 
$file = '/tmp/ignore_user.txt'; 
if(!file_exists($file)) { 
file_put_contents($file); 
} 
if(!$handle = fopen($file,'a+b')){ 
echo "not open file :".$file; 
exit; 
} 
$i=0; 
while($i<100) { 
$time = date("Y-m-d H:i:s",time()); 
echo $time."\n"; 
if(fwrite($handle,$time."\n")===false) { 
echo "not write file:".$file; 
exit; 
} 
echo "write file time:".$time."\n"; 
$i++; 
sleep(2); 
} 
fclose($handle);