how can I fire up carbon emacs (as editor instead of emacs in default) to edit a file under terminal.app?

Question

How to configure the bash file?

Answer 1

I use:

alias cemacs='open -a /Applications/Emacs.app' 

Then I can type cemacs foo.txt and have emacs open the file.

(Is that what you were asking? The question was a little vague.)

Answer 2

export EDITOR=/usr/bin/emacs

to your ~/.bash_profile