public static function getComposerLocation()
    {
        if (!\function_exists('shell_exec') || stripos(PHP_OS, 'win') === 0) {
            return self::DEFAULT_PATH;
        }

        // check for global composer install
        $path = trim(shell_exec('command -v composer'));

        // fall back to grav bundled composer
        if (!$path || !preg_match('/(composer|composer\.phar)$/', $path)) {
            $path = self::DEFAULT_PATH;
        }

        return $path;
    }