title: User Permissions in Ubuntu
body: <p>I want to access "sudoers" file and also access "su -" but I fail and get following error please check terminal output that I have tried. I am m-usman(admin) but not allow to edit or access ? :(</p>
  
  <pre><code>m-usman@muhammad-usman:~$ sudo gedit /etc/sudoers
  [sudo] password for m-usman:        
  m-usman is not in the sudoers file.  This incident will be reported.
  m-usman@muhammad-usman:~$ su -
  Password:   
  su: Authentication failure
  m-usman@muhammad-usman:~$ sudo visudo
  [sudo] password for m-usman: 
  m-usman is not in the sudoers file.  This incident will be reported.
  </code></pre>
  
  <p>How can I fix it?</p>