private function generatePartForPreferredIdentity()
    {
        if ($this->preferredIdentity === null) {
            return '';
        }
        if (!function_exists('posix_getpwnam')) {
            throw new Exception\LogicException('The POSIX extension must be installed to be able to set a preferred identity');
        }
        $pw = posix_getpwnam($this->preferredIdentity);
        if ($pw === false) {
            throw new Exception\LogicException('The preferred identity is one of a non-existent user');
        }

        return 'posix_setgid('.self::exportPhpValue($pw['gid']).');'.PHP_EOL.
            'posix_initgroups('.self::exportPhpValue($pw['name']).', '.self::exportPhpValue($pw['gid']).');'.PHP_EOL.
            'posix_setuid('.self::exportPhpValue($pw['uid']).');'.PHP_EOL;
    }
private function generatePartForPreferredIdentity()
    {
        if ($this->preferredIdentity === null) {
            return '';
        }
        if (!function_exists('posix_getpwnam')) {
            throw new Exception\LogicException('The POSIX extension must be installed to be able to set a preferred identity');
        }
        $pw = posix_getpwnam($this->preferredIdentity);
        if ($pw === false) {
            throw new Exception\LogicException('The preferred identity is one of a non-existent user');
        }

        return 'posix_setgid('.self::exportPhpValue($pw['gid']).');'.PHP_EOL.
            'posix_initgroups('.self::exportPhpValue($pw['name']).', '.self::exportPhpValue($pw['gid']).');'.PHP_EOL.
            'posix_setuid('.self::exportPhpValue($pw['uid']).');'.PHP_EOL;
    }
@throws Exception\LogicException

@return string