How to store uploaded files in a directory of the main domain from a subdomain upload form

please how can store uploaded file in my main domain directory should it be like this:

move_uploaded_file(https://example.com/uploads)

Solution

First step is to start here with handling uploaded files:
http://php.net/manual/en/function.move-uploaded-file.php

The first example is almost exactly what you want:

<?php
$uploads_dir = '/uploads';
foreach ($_FILES["pictures"]["error"] as $key => $error) {
    if ($error == UPLOAD_ERR_OK) {
        $tmp_name = $_FILES["pictures"]["tmp_name"][$key];
        // basename() may prevent filesystem traversal attacks;
        // further validation/sanitation of the filename may be appropriate
        $name = basename($_FILES["pictures"]["name"][$key]);
        move_uploaded_file($tmp_name, "$uploads_dir/$name");
    }
}
?>

You will need to make two edits. The $uploads_dir will need to have a relative path to where the files are uploaded. Let's say your form is in the root of your subdomain in subdomain.example.com/ and you want to move them to public_html/uploads. Your new $uploads_dir should look like the following:

$uploads_dir = __DIR__ . '/../public_html/uploads';

__DIR__ will give you the current director your php file is running in. This allows you to create a relative path to other directories.

The second edit is to update the $_FILES array to loop through the proper structure of what you are uploading. It might not be pictures as in the example.