WordPress at a glance
function is not described

install_blog() WP 3.0.0

Deprecated in from version 5.1.0. It is no longer supported and can be removed in future releases. It is recommended to replace this function with the same one.

Install an empty blog.

Creates the new blog tables and options. If calling this function directly, be sure to use switch_to_blog() first, so that $wpdb points to the new blog.

No Hooks.

Return

Null. Nothing.

Usage

install_blog( $blog_id, $blog_title );
$blog_id(int) (required)
The value returned by wp_insert_site().
$blog_title(string)
The title of the new site.
Default: ''

Notes

  • Global. wpdb. $wpdb WordPress database abstraction object.
  • Global. WP_Roles. $wp_roles WordPress role management object.

Changelog

Since 3.0.0 Introduced.
Deprecated 5.1.0

Code of install_blog() WP 5.5.1

<?php
function install_blog( $blog_id, $blog_title = '' ) {
	global $wpdb, $wp_roles;

	_deprecated_function( __FUNCTION__, '5.1.0' );

	// Cast for security.
	$blog_id = (int) $blog_id;

	require_once ABSPATH . 'wp-admin/includes/upgrade.php';

	$suppress = $wpdb->suppress_errors();
	if ( $wpdb->get_results( "DESCRIBE {$wpdb->posts}" ) ) {
		die( '<h1>' . __( 'Already Installed' ) . '</h1><p>' . __( 'You appear to have already installed WordPress. To reinstall please clear your old database tables first.' ) . '</p></body></html>' );
	}
	$wpdb->suppress_errors( $suppress );

	$url = get_blogaddress_by_id( $blog_id );

	// Set everything up.
	make_db_current_silent( 'blog' );
	populate_options();
	populate_roles();

	// populate_roles() clears previous role definitions so we start over.
	$wp_roles = new WP_Roles();

	$siteurl = $home = untrailingslashit( $url );

	if ( ! is_subdomain_install() ) {

		if ( 'https' === parse_url( get_site_option( 'siteurl' ), PHP_URL_SCHEME ) ) {
			$siteurl = set_url_scheme( $siteurl, 'https' );
		}
		if ( 'https' === parse_url( get_home_url( get_network()->site_id ), PHP_URL_SCHEME ) ) {
			$home = set_url_scheme( $home, 'https' );
		}
	}

	update_option( 'siteurl', $siteurl );
	update_option( 'home', $home );

	if ( get_site_option( 'ms_files_rewriting' ) ) {
		update_option( 'upload_path', UPLOADBLOGSDIR . "/$blog_id/files" );
	} else {
		update_option( 'upload_path', get_blog_option( get_network()->site_id, 'upload_path' ) );
	}

	update_option( 'blogname', wp_unslash( $blog_title ) );
	update_option( 'admin_email', '' );

	// Remove all permissions.
	$table_prefix = $wpdb->get_blog_prefix();
	delete_metadata( 'user', 0, $table_prefix . 'user_level', null, true );   // Delete all.
	delete_metadata( 'user', 0, $table_prefix . 'capabilities', null, true ); // Delete all.
}