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);
}

?>

Answer 1

$_SERVER['DOCUMENT_ROOT'] is created by your webserver (e.g. Apache) before calling PHP. If you're running your script via a cronjob, you're bypassing your webserver and the DOCUMENT_ROOT will not exist.

You should determine the location of your configuration file in another way. One way is to use PHP's built-in constants for file locations, like __FILE__ or __DIR__:

$dir = __DIR__ . "/configuration.php";

__DIR__ refers to the folder containing the current file, so this will become /home/user/public_html/folder/subfolder/configuration.php.

From what you're doing with $_SERVER['DOCUMENT_ROOT'] I assume your configuration file is one folder up from public_html, so you could do something like this:

$dir = __DIR__ . "/../../../configuration.php";