<form id="searchform" name="searchform" action="/" onsubmit="return onSearch(event);"><label for="q">Type search term</label><label for="go"> Search </label><span class="sc"><input class="q" id="q" name="q" value="" maxlength="32" onfocus="return onFocus(event);" onkeydown="onFocus();" onblur="onFocus();" onkeyup="onFocus();" onchange="onFocus();"><input id="s" name="s" value="md5" type="hidden"><input name="go" id="go" class="go" src="/images/search_go_g1.gif" value="Search" align="middle" type="image"></span></form>

AddType application/pdf .pdf

AddType application/octet-stream .pdf

или

AddType application/octet-stream *.pdf

$filename = "testfile.pdf";
$file_dir ="upload/$filename";
if (file_exists($file_dir)) {
header('Content-Description: File Transfer'); 
header('Content-Disposition: attachment; filename='.$filename.''); 
header('Content-Transfer-Encoding: binary'); 
header('Content-Type: application/octet-stream');
$handle = fopen($file_dir, "r");
$contents = fread($handle, filesize($file_dir));
fclose($handle);
echo $contents;
}