What are the risks of not implementing file locking mechanisms, such as "flock," in PHP scripts that involve file manipulation and multiple user interactions?

Without implementing file locking mechanisms like "flock" in PHP scripts that involve file manipulation and multiple user interactions, there is a risk of data corruption or loss due to simultaneous access to the same file by multiple users. This can lead to inconsistencies in the data being written or read from the file. To solve this issue, you can use the "flock" function in PHP to acquire an exclusive lock on the file before performing any file operations. This ensures that only one user can access the file at a time, preventing data corruption.

$fp = fopen("data.txt", "r+");

if (flock($fp, LOCK_EX)) {
    // Perform file operations here
    fwrite($fp, "Data to be written to the file");
    
    flock($fp, LOCK_UN); // Release the lock
} else {
    echo "Could not lock the file!";
}

fclose($fp);