Does php have a function to determine whether a file is open?

Question

Like the question, if you sometimes need to add content to a file, how can you ensure that what you write will not be opened and written in by another person?

What I want is to generate something randomly before the writing operation starts, and then delete it after the operation is completed;

Answer 1

File Lock

<?php

$fp = fopen("/tmp/lock.txt", "r+");

if (flock($fp, LOCK_EX)) {  // 进行排它型锁定
    ftruncate($fp, 0);      // truncate file
    fwrite($fp, "Write something here\n");
    fflush($fp);            // flush output before releasing the lock
    flock($fp, LOCK_UN);    // 释放锁定
} else {
    echo "Couldn't get the lock!";
}

fclose($fp);

?>

From : http://php.net/manual/zh/func...