Npm installation gyp error errno -13

  node.js, question

Mac notebook, install gyp to report error

pangangdeMacBook-Pro:~ pangang$ npm -v
 2.15.1
 pangangdeMacBook-Pro:~ pangang$ npm install -g node-gyp
 npm ERR!  tar.unpack untar error /Users/pangang/.npm/node-gyp/3.4.0/package.tgz
 npm ERR!  Darwin 15.5.0
 npm ERR!  argv "/usr/local/bin/node" "/usr/local/bin/npm" "install" "-g" "node-gyp"
 npm ERR!  node v4.4.3
 npm ERR!  npm  v2.15.1
 npm ERR!  path /usr/local/lib/node_modules/node-gyp
 npm ERR!  code EACCES
 npm ERR!  errno -13
 npm ERR!  syscall mkdir
 
 npm ERR!  Error: EACCES: permission denied, mkdir '/usr/local/lib/node_modules/node-gyp'
 npm ERR!  at Error (native)
 npm ERR!  { [Error: EACCES: permission denied, mkdir '/usr/local/lib/node_modules/node-gyp']
 npm ERR!  errno: -13,
 npm ERR!  code: 'EACCES',
 npm ERR!  syscall: 'mkdir',
 npm ERR!  path: '/usr/local/lib/node_modules/node-gyp',
 npm ERR!  fstream_type: 'Directory',
 npm ERR!  fstream_path: '/usr/local/lib/node_modules/node-gyp',
 npm ERR!  fstream_class: 'DirWriter',
 npm ERR!  fstream_stack:
 npm ERR!  [ '/usr/local/lib/node_modules/npm/node_modules/fstream/lib/dir-writer.js:35:25',
 npm ERR!  '/usr/local/lib/node_modules/npm/node_modules/mkdirp/index.js:47:53',
 npm ERR!  'FSReqWrap.oncomplete (fs.js:82:15)' ] }
 npm ERR!
 npm ERR!  Please try running this command again as root/Administrator.
 
 npm ERR!  Please include the following file with any support request:
 npm ERR!  /Users/pangang/npm-debug.log
 pangangdeMacBook-Pro:~ pangang$

* The global installation plug-in on *nix needs to be usedsudo

sudo npm install -g node-gyp