node.js - 什么是“/usr/local/bin/gc”，为什么在我升级 graphcool 客户端时会抛出错误？

Question

npm update -g graphcool

我正在从 v 0.5 升级到最新的 graphcool 客户端，但出现以下错误

npm ERR! path /usr/local/bin/gc
npm ERR! code EEXIST
npm ERR! Refusing to delete /usr/local/bin/gc: is outside /usr/local/lib/node_modules/graphcool and not a link
npm ERR! File exists: /usr/local/bin/gc
npm ERR! Move it away, and try again.

/usr/local/bin/gc 是什么，我应该按照它的要求删除它吗？