For many years, the default shell on Athena was tcsh. On April 2, 2009, the default shell for new accounts was changed to bash. This change did not affect existing users.
If you registered for your account in April 2009 or later, chances are your default shell is bash. For everyone else, it will be tcsh.
You can confirm what your current default shell is with the following command:
In the example above, the user is using "tcsh". Bash users would see the following output: