在不使用superglobals的情况下获取$ _SERVER [“DOCUMENT_ROOT”]

Question

I'm running a PHP script from the command line, so superglobals are not defined. How can I get the $_SERVER["DOCUMENT_ROOT"] without using the superglobal $_SERVER?

Answer 1

Superglobals such $_SERVER haven't been set yet (because Apache/Nginx/etc) sets these values. As you're running from the command line, there is no Apache/Nginx/etc to set them, thus resulting in them becoming NULL.

There are 2 alternatives you can use.

Using __DIR__

You can use the magic constant __DIR__ to output the directory of the current file.

php -r "echo __DIR__;"
/var/www/html

This will give different results depending on where you run it from. I.e: /var/www/html/lib/foo will return differently if you ran it from /var/www/html/views/index. - which is probably not what you're looking for.

Setting your own constant

Within your bootstrap file (as mentioned in this comment), you can set your own constant to be used throughout your application.

define('__DOCUMENT_ROOT__', __DIR__);

Now from within the page you run (as long as it uses your bootstrap file), you can call __DOCUMENT_ROOT__ constant to get the value that would mirror $_SERVER["DOCUMENT_ROOT"]. Though this would require you to use relative paths to include your bootstrap file.