Forcing to download a file using PHP

Question

I have a CSV file on my server. If a user clicks on a link it should download, but instead it opens up in my browser window.

My code looks as follows

Answer 1

To force download you may use Content-Type: application/force-download header, which is supported by most browsers:

function downloadFile($filePath)
{
    header("Content-type: application/octet-stream");
    header('Content-Disposition: attachment; filename="' . basename($filePath) . '"');
    header('Content-Length: ' . filesize($filePath));
    readfile($filePath);
}

A BETTER WAY

Downloading files this way is not the best idea especially for large files. PHP will require extra CPU / Memory to read and output file contents and when dealing with large files may reach time / memory limits.

A better way would be to use PHP to authenticate and grant access to a file, and actual file serving should be delegated to a web server using X-SENDFILE method (requires some web server configuration):

• X-SENDFILE is natively supported by Lighttpd: https://redmine.lighttpd.net/projects/1/wiki/X-LIGHTTPD-send-file
• Apache requires mod_xsendfile module: https://tn123.org/mod_xsendfile/ On Ubuntu may be installed by: apt install libapache2-mod-xsendfile
• Nginx has a similar X-Accel-Redirect header: https://www.nginx.com/resources/wiki/start/topics/examples/xsendfile/

After configuring web server to handle X-SENDFILE, just replace readfile($filePath) with header('X-SENDFILE: ' . $filePath) and web server will take care of file serving, which will require less resources than using PHP readfile.

(For Nginx use X-Accel-Redirect header instead of X-SENDFILE)

Note: If you end up downloading empty files, it means you didn't configure your web server to handle X-SENDFILE header. Check the links above to see how to correctly configure your web server.