PHP get domain name

Similar question has been asked in stackoverflow before.

See here: PHP $_SERVER['HTTP_HOST'] vs. $_SERVER['SERVER_NAME'], am I understanding the man pages correctly?

Also see this article: http://shiflett.org/blog/2006/mar/server-name-versus-http-host

Recommended using HTTP_HOST, and falling back on SERVER_NAME only if HTTP_HOST was not set. He said that SERVER_NAME could be unreliable on the server for a variety of reasons, including:

• no DNS support
• misconfigured
• behind load balancing software

Source: http://discussion.dreamhost.com/thread-4388.html

To answer your question, these should work as long as:

• Your HTTP server passes these values along to PHP (I don't know any that don't)
• You're not accessing the script via command line (CLI)

But, if I remember correctly, these values can be faked to an extent, so it's best not to rely on them.

My personal preference is to set the domain name as an environment variable in the apache2 virtual host:

# Virtual host
setEnv DOMAIN_NAME example.com

And read it in PHP:

// PHP
echo getenv(DOMAIN_NAME);

This, however, isn't applicable in all circumstances.