WordPress Engine shortcode

gistfile1.php

<?php

class Marko_Shortcodes {

	public function __construct() {
		add_shortcode( 'engine_info', array( $this, 'engine_info' ) );
	}

	public function engine_info( $atts ) {
		global $wp_version, $wpdb, $batcache, $wp_object_cache;

		$html  = '<table style="max-width: 400px; width: 100%;">';
		$html .= '<tr><td>WordPress version</td><td>' . $wp_version . '</td></tr>';

		if( is_multisite() ) {
			$html .= '<tr><td>WordPress type</td><td>Network installation</td></tr>';
		}
		else {
			$html .= '<tr><td>WordPress type</td><td>Single installation</td></tr>';
		}

		$html .= '<tr><td>Image manipulator</td><td>' . _wp_image_editor_choose() . '</td></tr>';

		if ( isset( $batcache ) && is_object( $batcache ) && method_exists( $wp_object_cache, 'incr' ) ) {
			$html .= '<tr><td>Advanced cache</td><td>Batcache</td></tr>';
		}

		if( class_exists( 'APC_Object_Cache' ) ) {
			$html .= '<tr><td>Object cache</td><td>APC Object Cache</td></tr>';
		}

		$html .= '<tr><td style="height:10px"></td></tr>';

		$html .= '<tr><td>OS type</td><td>' . php_uname('s') . '</td></tr>';
		$html .= '<tr><td>Linux distro</td><td>' . $this->get_linux_distro() . '</td></tr>';
		$html .= '<tr><td>Webserver</td><td>' . $_SERVER["SERVER_SOFTWARE"] . '</td></tr>';
		$html .= '<tr><td>MySQL</td><td>' . $wpdb->db_version() . '</td></tr>';
		$html .= '<tr><td>PHP type</td><td>' . php_sapi_name() . '</td></tr>';
		$html .= '<tr><td>PHP version</td><td>' . phpversion() . '</td></tr>';
		$html .= '<tr><td>APC cache</td><td>' . phpversion( 'apc' ) . '</td></tr>';
		$html .= '<tr><td>GD version</td><td>' . gd_info()['GD Version'] . '</td></tr>';

		if( phpversion( 'imagick' ) ) {
			$html .= '<tr><td>Imagick version</td><td>' . phpversion( 'imagick' ) . '</td></tr>';
		}

		if( phpversion( 'gmagick' ) ) {
			$html .= '<tr><td>Gmagick version</td><td>' . phpversion( 'gmagick' ) . '</td></tr>';
		}

		$html .= '</table>';

		return $html;
	}

	private function get_linux_distro() {
		$distros = array(
			'Arch'   => 'arch-release',
			'Debian' => 'debian_version',
			'Fedora' => 'fedora-release',
			'Ubuntu' => 'lsb-release',
			'Redhat' => 'redhat-release',
			'CentOS' => 'centos-release'
		);

		foreach ( $distros as $distro => $release_file ) {
			if ( file_exists( '/etc/' . $release_file ) ) {
				return $distro . ' ' . file_get_contents( '/etc/' . $release_file );
			}
		}
	}

}