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do_robots()

do_robots()

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Displays the default robots.txt file content.

Source

function do_robots() {
	if ( ! headers_sent() ) {
		header( 'Content-Type: text/plain; charset=utf-8' );
	}

	/**
	 * Fires when displaying the robots.txt file.
	 *
	 * @since 2.1.0
	 */
	do_action( 'do_robotstxt' );

	$output = "User-agent: *\n";
	$public = (bool) get_option( 'blog_public' );

	$output .= 'Disallow: ' . wp_parse_url( admin_url(), PHP_URL_PATH ) . "\n";
	$output .= 'Allow: ' . wp_parse_url( admin_url( 'admin-ajax.php' ), PHP_URL_PATH ) . "\n";

	/**
	 * Filters the robots.txt output.
	 *
	 * @since 3.0.0
	 *
	 * @param string $output The robots.txt output.
	 * @param bool   $public Whether the site is considered "public".
	 */
	echo apply_filters( 'robots_txt', $output, $public );
}

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Hooks

do_action( ‘do_robotstxt’ )

Fires when displaying the robots.txt file.

apply_filters( ‘robots_txt’, string $output, bool $public )

Filters the robots.txt output.

UsesDescription
wp_parse_url()wp-includes/http.php

A wrapper for PHP’s parse_url() function that handles consistency in the return values across PHP versions.

admin_url()wp-includes/link-template.php

Retrieves the URL to the admin area for the current site.

do_action()wp-includes/plugin.php

Calls the callback functions that have been added to an action hook.

apply_filters()wp-includes/plugin.php

Calls the callback functions that have been added to a filter hook.

get_option()wp-includes/option.php

Retrieves an option value based on an option name.

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Changelog

VersionDescription
5.3.0Remove the "Disallow: /" output if search engine visibility is discouraged in favor of robots meta HTML tag via wp_robots_no_robots() filter callback.
2.1.0Introduced.

User Contributed Notes

  1. Skip to note 2 content
    wp_kc
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    Some examples of how robots.txt file content can be altered.

    /**
 * Add Disallow for some file types.
 * Add "Disallow: /wp-login.php/\n".
 * Remove "Allow: /wp-admin/admin-ajax.php\n".
 * Calculate and add a "Sitemap:" link.
 */
add_filter( 'robots_txt', function( $output, $public ) {
	/**
	 * If "Search engine visibility" is disabled,
	 * strongly tell all robots to go away.
	 */
	if ( '0' == $public ) {
		$output = "User-agent: *\nDisallow: /\nDisallow: /*\nDisallow: /*?\n";
	} else {
		/**
		 * Disallow some file types
		 */
		foreach( array( 'jpeg','jpg','gif','png','mp4','webm','woff','woff2','ttf','eot' ) as $ext ) {
			$output .= "Disallow: /*.{$ext}$\n";
		}

		/**
		 * Get site path.
		 */
		$site_url = parse_url( site_url() );
		$path	  = ( ! empty( $site_url['path'] ) ) ? $site_url['path'] : '';

		/**
		 * Add new disallow.
		 */
		$output .= "Disallow: $path/wp-login.php\n";

		/**
		 * Remove line that allows robots to access AJAX interface.
		 */
		$robots = preg_replace( '/Allow: [^\0\s]*\/wp-admin\/admin-ajax\.php\n/', '', $output );

		/**
		 * If no error occurred, replace $output with modified value.
		 */
		if ( ! is_null( robots ) ) {
			$output = $robots;
		}
		/**
		 * Calculate and add a "Sitemap:" link.
		 * Modify as needed.
		 */
		$output .= "Sitemap: {$site_url['scheme']}://{$site_url[ 'host' ]}/sitemap_index.xml\n";
	}

	return $output;

}, 99, 2 );  // Priority 99, Number of Arguments 2.

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