title: Program exit status and $?
body: <p>C++ Primer book i read says that </p>
  
  <blockquote>
    <p>The value returned from main is accessed in a system dependent manner.
    On both UNIX and Windows systems, afar executing the program you must
    issue an appropriate echo command. On UNIX we obtain the status by
    echo $?</p>
  </blockquote>
  
  <p>So, if the program is</p>
  
  <pre><code>int main ()
  {
      return -88;
  }
  </code></pre>
  
  <p>Why does <code>echo $?</code> not return it? (168 is printed upon <code>echo</code>)</p>