force download

• $file = "filename.ext";
• // Quick check to verify that the file exists
• if( !file_exists($file) ) die("File not found");
• // Force the download
• header("Content-Disposition: attachment; filename="" . basename($file) . """);
• header("Content-Length: " . filesize($file));
• header("Content-Type: application/octet-stream;");
• readfile($file);

https://www.abeautifulsite.net/forcing-file-downloads-in-php

来源：https://www.cnblogs.com/qinqiu/p/10808910.html