The shell is a command interpreter and it is your interface to the
UNIX operating system. When you log in to the system, a shell
is started to receive your commands. There are many shells to
choose from, all with different features and enhancements. The
shells that you will probably use here are the C-Shell (csh) or
the Enhanced C-Shell (tcsh).
csh is an enhanced version of the Bourne shell, providing
many new features such as aliasing, command history, and job
control, to name just a few.
tcsh is the same as the csh, except it provides command-line
recall and editing based on Gnu EMACS editing commands. tcsh
provides many more enhancements than just command-line editing;
a discussion of the options can be found in the online manual pages
for tcsh.
To change your default shell, use the passwd -s command and enter the name of the shell that you wish to use.