<?php

$fp = fopen("/tmp/lock.txt","w+");
if(flock($fp, LOCK_EX)){// 进行排它型锁定
	fwrite($fp,"Write something here\n");
	flock($fp, LOCK_UN);// 释放锁定
}else{
	 echo "Couldn't lock the file !";
}
fclose($fp);