使用PHP强制下载未知文件类型的文件

header('Content-Type: application/octet-stream');
header('Content-Disposition: attachment; filename="file.txt"');
readfile('path/to/unknown/file.txt');

header('Content-Type: application/octet-stream');
header('Content-Disposition: attachment; filename="file.txt"');
readfile('path/to/unknown/file.txt');

$fileinfo = new finfo(FILEINFO_MIME);
$mime_type = $fileinfo->buffer(file_get_contents('path/to/unknown/file.txt'));

header('Content-Type: ' . $mime_type);
header('Content-Disposition: attachment; filename="file.txt"');
readfile('path/to/unknown/file.txt');