噓~

* change to tcsh for login
chsh -s /usr/bin/tcsh

* change to bash for login
chsh -s /bin/bash

 
* check which shell do you use when you login?
vi /etc/passwdd

* change shell to csh now
csh
* change shell to bash now
bash

* check which shell do you use now?
echo shell
echo SHELL


REFERENCE