PHP Code to ping search engines like Google and Bing.This code can be used to notify search engines about you website content.You can ping individual URL or complete sitemap containing list of URL on your website.You can read more in this post https://udinra.com/blog/php-code-to-ping-google-bing-and-ask-com .
I have included Google and Bing.Feel free to enhance this post to include other search engines.