How to auto post to Facebook page on new update in my webapp?

I want to know whether there are ways to post on social networking sites like Facebook, LinkedIn, Twitter from my back-end technology like PHP. Here for my case user interaction will not be there, user won't click or authorize fb,twitter apps. My page app credentials will be there anyways, and whenever there is an update, I want to post to my page using those credentials from my back-end service. Lets say, if some author published an article in my blog, I want to share that immediately on my fb page.