title: cd - results in "-bash: cd: OLDPWD not set"
body: <p>I tried following <a href="https://help.ubuntu.com/community/UsingTheTerminal" rel="noreferrer">these instructions</a> to go back to the previous directory, but that results in "-bash cd: OLDPWD not set".</p>
  
  <p><a href="https://i.stack.imgur.com/ooOJD.png" rel="noreferrer"><img src="https://i.stack.imgur.com/ooOJD.png" alt="enter image description here"></a></p>
  
  <p>How could I do what I want?</p>
  
  <p>Thank you.</p>