PHP File: Locking and Unlocking File

PHP File Tips - Part 12: You can lock a file use flock() function. This function allows you to performe a simple reader/write model. Once a file is locked with flock(), other processing attempting to write to file have to wait until unlock. It avoid multiprocess at a file that can corrupt it.

<?php
$f = "test2.txt";

$fo = fopen($f, "wb+") or die("cannot open");

if(flock($fo, LOCK_EX)){
  fwrite($fo,"test add a 2 string") or die("cannot write to file");
  flock($fo, LOCK_UN);
}else{
  die("Cannot lock file");
}

fclose($fo);
echo "sucess";
?>