如何将 Composer 升级到 v2？

Question

我正在尝试将 Composer 升级到 Composer2（从 Composer1）。

richb201@richb201-XPS-13-9370:/opt/docker-substantiator2/app/vendor/sendpulse-rest-api-php-master/src$ composer selfupdate
Updating to version 2.0.13 (stable channel).
   Downloading (100%)         

                                                                                                        
  [ErrorException]                                                                                      
  rename(/home/richb201/.cache/composer/composer-temp.phar,/usr/local/bin/composer): Permission denied  

我究竟做错了什么？