1. Popular
   1. Bourne (sh)
   2. C Shell (csh)
   3. Korn Shell (ksh)
   4. Bourne Again Shell (bash)
2. Prompt
   1. $
      1. bash
      2. sh
      3. ksh
   2. %
      1. csh
3. Change
   1. Command
      1. chsh
4. Display
   1. Command
      1. echo $SHELL