title: npm uninstalls itself on npm update
body: <p>I looked for a similar topic in stackoverflow but could not find one, so here it goes.</p>
  
  <p>I've been looking at MEAN stack documentation at <a href="http://learn.mean.io/" rel="noreferrer">http://learn.mean.io/</a> and just checking some shell commands.</p>
  
  <p>I tried to update npm via </p>
  
  <pre><code>npm update -g npm
  </code></pre>
  
  <p>but this came out to give errors</p>
  
  <pre><code>npm ERR! Error: EACCES, unlink '/usr/local/lib/node_modules/npm'
  npm ERR!  { [Error: EACCES, unlink '/usr/local/lib/node_modules/npm']
  npm ERR!   errno: 3,
  npm ERR!   code: 'EACCES',
  npm ERR!   path: '/usr/local/lib/node_modules/npm' }
  npm ERR!
  npm ERR! Please try running this command again as root/Administrator.
  
  npm ERR! System Darwin 14.0.0
  npm ERR! command "node" "/usr/local/bin/npm" "update" "-g" "npm"
  npm ERR! cwd /Users/cihankoseoglu
  npm ERR! node -v v0.10.33
  npm ERR! npm -v 1.4.28
  npm ERR! path /usr/local/lib/node_modules/npm
  npm ERR! code EACCES
  npm ERR! errno 3
  npm ERR! stack Error: EACCES, unlink '/usr/local/lib/node_modules/npm'
  npm ERR! error rolling back Error: EACCES, unlink '/usr/local/lib/node_modules/npm'
  npm ERR! error rolling back  { [Error: EACCES, unlink '/usr/local/lib/node_modules/npm']
  npm ERR! error rolling back   errno: 3,
  npm ERR! error rolling back   code: 'EACCES',
  npm ERR! error rolling back   path: '/usr/local/lib/node_modules/npm' }
  npm ERR! not ok code 0
  </code></pre>
  
  <p>so i tried</p>
  
  <pre><code>sudo npm update -g npm
  </code></pre>
  
  <p>but after this command runs , my zsh shell can't find npm. when i type any npm command it simply returns command not found. I had to reinstall Node. what could be possibly causing this? Is it uninstalling npm or altering its PATH in the background for reasons unbeknowst to me?</p>