Here is the simple php code to upload a pdf file
/* file upload */
$allowedExts = array("pdf", "doc", "docx");
$targetfolder = $resume_upload_path; // UPLOAD path e.g '/home/public_html/upload'
$random_num=rand(1000,9999);
$targetfolder = $targetfolder . $random_num.str_replace(' ', '_', basename($_FILES['resume_pdf']['name'])) ;
$targetpath = $root_upload_path . $random_num.str_replace(' ', '_', basename($_FILES['resume_pdf']['name'])) ;
$file_type=$_FILES['resume_pdf']['type'];
$extension = end(explode(".", $_FILES["resume_pdf"]["name"]));
if ( 12000 < $_FILES["resume_pdf"]["size"] ) {
echo "error";
exit;
}
if ( ! ( in_array($extension, $allowedExts ) ) ) {
echo "error";
exit;
}
$file_path="";
if(move_uploaded_file($_FILES['resume_pdf']['tmp_name'], $targetfolder))
{
$file_path=$targetpath ;
}
else {
echo "error";
exit;
}
/* file upload end*/
where $file_path is the path of uploaded file