Instead of messing with the /etc/passwd file, you can use the 'chsh' command:
See the manpage fmi.
> man chsh
You'll need to know the path for bash:
> which bash
.bashrc is a good file to use. You can get all kinds of examples from searching and you most likely will have a copy of one on your system already. Check the /etc directory. I have one called /etc/bash.bashrc.
Here's more info: