xxx@CN_C02xxxxx6M ~ % npm install -g yarn npm ERR! code EACCES npm ERR! syscall mkdir npm ERR! path /usr/local/lib/node_modules/yarn npm ERR! errno -13 npm ERR! Error: EACCES: permission denied, mkdir '/usr/local/lib/node_modules/yarn' npm ERR! [Error: EACCES: permission denied, mkdir '/usr/local/lib/node_modules/yarn'] { npm ERR! errno: -13, npm ERR! code: 'EACCES', npm ERR! syscall: 'mkdir', npm ERR! path: '/usr/local/lib/node_modules/yarn' npm ERR! } npm ERR! npm ERR! The operation was rejected by your operating system. npm ERR! It is likely you do not have the permissions to access this file as the current user npm ERR! npm ERR! If you believe this might be a permissions issue, please double-check the npm ERR! permissions of the file and its containing directories, or try running npm ERR! the command again as root/Administrator.
npm ERR! A complete log of this run can be found in: npm ERR! /Users/xxx/.npm/_logs/2022-12-06T11_15_27_852Z-debug-0.log
原理：
报这个错，根本原因是由于npm全局安装模块的默认路径没有权限，通常有以下几种方式解决：
修改全局安装路径的权限（可能会不安全）
修改默认安装路径（推荐）
借助其他方式安装
解决方案
方案一：修改全局安装路径
step1:打开环境变量配置文件，配置环境变量
mkdir ~/.npm-global npm config set prefix '~/.npm-global'
