I want to check if a WordPress installation is working from a subdirectory.

Common methods to achieve this are listed here: https://codex.wordpress.org/Giving_WordPress_Its_Own_Directory

these usually involve changing an index file and requiring WordPress main file from there, perhaps changing rules in htaccess if using Apache - there's no setting up constants from what I can see

so, how would you detect reliably if WordPress is not running from a directory root?


3 Answers 3


You need to check if the siteurl differs from the home URL:

if ( get_option( 'siteurl' ) !== get_option( 'home' ) ) { // whatever

This also works if home is a subdirectory of the root, with WordPress installed in yet another subdirectory. For example: domain.com/blog (URL) and domain.com/blog/wordpress (siteurl).

  • thanks I also thought of that and should have mentioned in OP question -- however, do you think it's reliable in 100% of the cases?
    – unfulvio
    Commented Feb 3, 2016 at 8:41
  • Yes, because that is the definition of where WordPress is installed. If it differs from the URL, it's a subdirectory install.
    – fischi
    Commented Feb 3, 2016 at 9:56
  • what if it's not a subdirectory install but the URLS are still different? For example sites which have different domains pointing to the same install
    – paul
    Commented Feb 4, 2016 at 10:17
  • @paul even then both options are the same, and the handling of multiple domains is done somewhere else. Do you have an example where this is not the case?
    – fischi
    Commented Feb 4, 2016 at 10:18
  • 1
    This is not a valid way to check if WordPress is in a subdirectory though. Because siteurl and home can be the same. For instance, domain.com/site1 is simply the site itself, that it's hosted on domain.com is irrelevant. Both siteurl and home can be set to https://domain.com/site1. I am just trying to say that siteurl and home are user input "fields" and they can be the same even if the site is located in a subdirectory. Of course this method will for sure work when the site root is the FQN and WP files are in a subdir. Commented May 12, 2020 at 18:41

I just came across for the same question and found another way to figure it out. You can also use the defined Constants from the wp-config.php file. SUBDOMAIN_INSTALL would be the key.

Example wp-config excerpt for Multisite settings would be

define('WP_ALLOW_MULTISITE', true );
define('MULTISITE', true);
define('SUBDOMAIN_INSTALL', false);
define('DOMAIN_CURRENT_SITE', 'intern.cc.dev');
define('PATH_CURRENT_SITE', '/');

In your code

// only run condition, when we are in MS
if( is_multisite() ):

   // check for subfolder installation flag
   if( SUBDOMAIN_INSTALL === false):

      // optional, check if you are on the home WP or a sub WP
      if( get_current_blog_id() > 1):

         // do whatever you need to to here

      endif; // end blog id check
   endif; // end subfolder installation 
endif; // end multisite check

Try this:

if ( '/' !== site_url( '', 'relative') ) {

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