Force File Download in PHP

To provide a download link for a file in PHP, you can use the following steps:

1. Retrieve the File Information:

   $filePath = '/path/to/file/on/disk.jpg';
   
   if(file_exists($filePath)) {
       $fileName = basename($filePath);
       $fileSize = filesize($filePath);
   } else {
       die('The provided file path is not valid.');
   }

2. Output Headers:

   header("Cache-Control: private");
   header("Content-Type: application/stream");
   header("Content-Length: ".$fileSize);
   header("Content-Disposition: attachment; filename=".$fileName);

3. Output the File:

   readfile ($filePath);                   
   exit();

Note: Be cautious if implementing this in a function to allow downloads of arbitrary files, as you need to prevent directory traversal and restrict downloads to a defined area.