title: Using 'sudo apt-get install build-essentials'
body: <p>I was trying to use <code>sudo apt-get install build-essentials</code> to install the g++ compiler on my Ubuntu Linux box. But it gave me the following message:</p>
  
  <blockquote>
    <p>Reading package lists... Done </p>
    
    <p>Building dependency tree<br>
       Reading state information... Done</p>
    
    <p>E: Unable to locate package build-essentials</p>
  </blockquote>
  
  <p>How do I fix this problem?</p>