In message <57704.127.0.0.1.1143086361.squirrel@www.88thstreet.com>, "radhika" 
writes:
>I tried it and get this message:
>>su root bash
>>Password:
>>sh: Can't open bash

Do you have bash installed?

I would warn you, if you can't debug this error message without help, you
probably don't understand what you're doing enough to make the assertion that
you want to use bash instead of another shell.  If you don't understand what
you're doing, switching to bash won't help.

-s