is_main_site( int $site_id = null, int $network_id = null )

Determines whether a site is the main site of the current network.

Parameters

$site_id

(Optional) Site ID to test. Defaults to current site.

Default value: null

$network_id

(Optional) Network ID of the network to check for.<br> Defaults to current network.

Default value: null

Return

(bool) True if $site_id is the main site of the network, or if not running Multisite.

Source

File: wp-includes/functions.php 

function is_main_site( $site_id = null, $network_id = null ) {
	if ( ! is_multisite() ) {
		return true;
	}

	if ( ! $site_id ) {
		$site_id = get_current_blog_id();
	}

	$site_id = (int) $site_id;

	return $site_id === get_main_site_id( $network_id );
}

Expand Source Code View on GitHub

Related

Used By

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Checks if updates are intercepted by a filter.
wp-includes/user.php: wp_schedule_update_user_counts()

Schedules a recurring recalculation of the total count of users.
wp-includes/ms-deprecated.php: is_main_blog()

Deprecated functionality to determin if the current site is the main site.
wp-includes/option.php: delete_expired_transients()

Deletes all expired transients.
wp-includes/class-wp-rewrite.php: WP_Rewrite::rewrite_rules()

Constructs rewrite matches and queries from permalink structure.
wp-includes/ms-functions.php: wp_schedule_update_network_counts()

Schedules update of the network-wide counts for the current network.
wp-includes/ms-functions.php: maybe_redirect_404()

Corrects 404 redirects when NOBLOGREDIRECT is defined.
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wp-includes/functions.php: _wp_upload_dir()

A non-filtered, non-cached version of wp_upload_dir() that doesn’t check the path.
wp-admin/press-this.php: wp_load_press_this()
wp-admin/includes/upgrade.php: wp_should_upgrade_global_tables()

Determine if global tables should be upgraded.
wp-admin/includes/upgrade.php: wp_upgrade()

Runs WordPress Upgrade functions.
wp-admin/includes/class-wp-automatic-updater.php: WP_Automatic_Updater::run()

Kicks off the background update process, looping through all pending updates.
wp-admin/includes/class-wp-ms-sites-list-table.php: WP_MS_Sites_List_Table::column_cb()

Handles the checkbox column output.
wp-admin/includes/ms.php: avoid_blog_page_permalink_collision()

Avoids a collision between a site slug and a permalink slug.
wp-admin/includes/ms.php: wpmu_delete_blog()

Deletes a site.
Show 12 more used by Hide more used by

Changelog

Changelog
Version Description
4.9.0 The $network_id parameter was added.
3.0.0 Introduced.