Cron作业没有运行php脚本

Question

I have created a cron job in my cpanel using command below:

/usr/bin/php -q /home/user/public_html/folder/subfolder/sync.php

The content of syns.php is almost like this. It works without error when I run it with the domain like domain.com/folder/subfolder/sync.php but I can not see the expected result when the cron job supposed to run which means cron job is not running the script. So can anyone tell me what might be the problem?

<?php

$dir = str_replace("public_html","", $_SERVER["DOCUMENT_ROOT"]);
$dir = $dir . "configuration.php";

if (file_exists($dir)) 
{
    require_once($dir);
    sync();
} 
else
{
    // echo ("Can't find the access data.");
}

function sync()
{
    $connection = mysqli_connect(DB_HOST, DB_USER, DB_PASSWORD, DB_DATABASE);
    if(mysqli_connect_errno())
    {
        // echo ("Failed to connect the database.");
        exit();
    }
    else
    {
        if(mysqli_ping($connection))
        {
            $query = "SELECT OR UPDATE WHATEAVER FROM TABLE;";
            $result = mysqli_multi_query($connection, $query);
            if($result)
            {
                // Do stuff
            }
            else
            {
                // echo("Failed to excute the query.");
            }
        }
        else
        {
            // echo("Failed to ping the connection.");
        }
    }
    mysqli_close($connection);
}

?>