Custom shortcode that writes to file

Question

I'm trying to maybe do too much in a shortcode call. Here's the code I have:

        //[rand]
function randnumber_func( $atts ){
 $digits = 4;
 $randnumber = rand(pow(10, $digits-1), pow(10, $digits)-1);
 $space = "\r\n";
 $myFile = "offer_codes.txt";
    $fh = fopen($myFile, 'a+') or die("can't open file");
    $stringData = date("F j, Y, g:i a") . " - " . $randnumber;
    fwrite($fh, $stringData.$space);
    fclose($fh);
 return $randnumber;
}
add_shortcode( 'rand', 'randnumber_func' );

I want to create a random 4 digit number and have it printed to the page. I also want to take that random number, append the date to it, and have that written to a text file. It works in PHP, but not when I call it via a shortcode. Is something it Wordpress stripping it out or do I have it written incorrectly for the shortcode function?

Answer 1

Your code works for me on a development server. As is, it saves to the site root directory. My guess is that you are trying to write to a directory to which the server does not have write access. I would suggest saving to wp-content/uploads or some other directory where you should reasonably have write access.

$upload_dir = wp_upload_dir();
$myFile = $upload_dir['basedir']."/offer_codes.txt";