For those of you who sometimes make sites that isn't pre-built with a sitemap generator, there is one I like to use as an alternative. Go to this website and download / copy code.
Make changes as applicable in php file for your website. Don't forget to add a crontab!
Example: if your are in shell do "sudo crontab -e" and enter similar code into file
0 0 * * 0 cd /path/to/php/bin/; ./php /home/website/sitemap.php
This code will make it generate weekly.