title: Bash - what's the use of "fi ;;"?
body: <p>I have been searching everywhere for an explanation. Here's a real example taken from the apt-fast.sh script:</p>
  
  <pre><code>if [ ! -x /usr/bin/axel ]
  then echo "axel is not installed, perform this?(y/n)"
      read ops
      case $ops in
       y) if apt-get install axel -y --force-yes
             then echo "axel installed"
          else echo "unable to install the axel. you are using sudo?" ; exit
          fi ;;
       n) echo "not possible usage apt-fast" ; exit ;;
      esac
  fi
  </code></pre>
  
  <p>What's the use of <code>"fi ;;"</code> in the middle of the <code>if</code> block?</p>