title: Unset is not useful? (Korn shell)
body: <p>I'm reading this:</p>
  
  <blockquote>
    <p>You can delete a variable with the command <code>unset</code> <em>varname</em>. Normally this is not useful, since all variables that don't exist are assumed to be null, i.e., equal to empty string "". But if you use the option <code>nounset</code> which causes the shell to indicate an error when it encounters an undefined variable, then you may be interested in <code>unset</code>.</p>
  </blockquote>
  
  <p>My first question is: I cannot see why the use of <code>unset</code> be not useful; if I want to put my variable to <code>null</code> I can use it (or set <em>variable=""</em> or <em>variable=</em>). On the other hand, if I have a variable that doesn't exist, I don't know why I should have to use it..</p>
  
  <p>My second question is: Why may I be interested in <code>unset</code> in that case?</p>