Can someone point me to the right command to to run another shell on top of your default shell?

Thanks

PS If admin sees this It is not home work. I am old man who wants to learn unix in my spare time. I CURRENTLY DO NOT GO SCHOOL, COLLEGE OR UNIVERSITY.

After you login, # preceed comments and are not commands you enter.

# to get the bash shell
/bin/bash
# to get the ksh shel
/bin/ksh

Thank you.

Can i ask you one last question.

Lets say my default shell is bash and then i load up csh and then ksh. How would i exit csh without exiting ksh?

so basically i gone from bash > csh > ksh and i wish to close csh

Moderator's Comments:

edit by bakunin: You have asked the same question already here. Do not post the same question twice. Thraed closed.