title: Permission denied when trying to self-update composer
body: <p>When I am trying to self-update my composer, I get <em>"Permission Denied"</em> error.</p>
  
  <p>Even when I use <code>sudo /usr/bin/composer.phar self-update</code>, it shows me <code>command not found</code>.</p>
  
  <p>Please help me I have no idea about composer </p>