download in php

 https://www.php.net/manual/en/function.readfile.php

https://www.phptutorial.net/php-tutorial/php-download-file/

<?php

if(isset($_REQUEST["q"])){

    // Get parameters

    $filepath = urldecode($_REQUEST["q"]); // Decode URL-encoded string

//echo $filepath;

/* Check if the file name includes illegal characters

    like "../" using the regular expression */

    // if(preg_match('/^[^.][-a-z0-9_.]+[a-z]$/i', $file)){

    //     $filepath = "images/" . $file;

        // Process download

       echo basename($filepath);

    }

       /* if(file_exists($filepath)) {

            header('Content-Description: File Transfer');

            header('Content-Type: application/octet-stream');

            header('Content-Disposition: attachment; filename="'.basename($filepath).'"');

            header('Expires: 0');

            header('Cache-Control: public');

            header('Pragma: public');

            header('Content-Length: ' . filesize($filepath));

            flush(); // Flush system output buffer

            readfile($filepath);

            die();

        } else {

            http_response_code(404);

            die();

        }

    } else {

        die("Invalid file name!");

    }*/

//}

?>