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

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

Parameters

$site_id int Optional
Site ID to test. Defaults to current site.

Default: null

$network_id int Optional
Network ID of the network to check for.
Defaults to current network.

Default: null

Return

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

More Information

Replaces function is_main_blog(), deprecated since 3.0.0. (wp-includes/ms-deprecated.php)

Source

File: wp-includes/functions.php. View all references

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

Used By

Used By Description
wp_schedule_update_user_counts() wp-includes/user.php

Schedules a recurring recalculation of the total count of users.
WP_MS_Sites_List_Table::site_states() wp-admin/includes/class-wp-ms-sites-list-table.php

Maybe output comma-separated site states.
WP_Site_Health_Auto_Updates::test_wp_version_check_attached() wp-admin/includes/class-wp-site-health-auto-updates.php

Checks if updates are intercepted by a filter.
delete_expired_transients() wp-includes/option.php

Deletes all expired transients.
wp_load_press_this() wp-admin/press-this.php
_wp_upload_dir() wp-includes/functions.php

A non-filtered, non-cached version of wp_upload_dir() that doesn’t check the path.
WP_MS_Sites_List_Table::column_cb() wp-admin/includes/class-wp-ms-sites-list-table.php

Handles the checkbox column output.
wp_should_upgrade_global_tables() wp-admin/includes/upgrade.php

Determine if global tables should be upgraded.
WP_Automatic_Updater::run() wp-admin/includes/class-wp-automatic-updater.php

Kicks off the background update process, looping through all pending updates.
avoid_blog_page_permalink_collision() wp-admin/includes/ms.php

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

Delete a site.
wp_upgrade() wp-admin/includes/upgrade.php

Runs WordPress Upgrade functions.
WP_Rewrite::rewrite_rules() wp-includes/class-wp-rewrite.php

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

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

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

Gets the size of a directory.
is_main_blog() wp-includes/ms-deprecated.php

Deprecated functionality to determin if the current site is the main site.

Changelog

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

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Licensed under the GNU GPLv2+ License.
https://developer.wordpress.org/reference/functions/is_main_site