macos下npm淘宝镜像安装失败

报错：

npm ERR! Error: EACCES: permission denied, symlink '../lib/node_modules/cnpm/bin/cnpm' -> '/usr/local/bin/cnpm'

npm ERR!  [Error: EACCES: permission denied, symlink '../lib/node_modules/cnpm/bin/cnpm' -> '/usr/local/bin/cnpm'] {

npm ERR!   errno: -13,

npm ERR!   code: 'EACCES',

npm ERR!   syscall: 'symlink',

npm ERR!   path: '../lib/node_modules/cnpm/bin/cnpm',

npm ERR!   dest: '/usr/local/bin/cnpm'

npm ERR! }

新命令：

sudo npm install -g cnpm --registry=https://registry.npm.taobao.org