How do I make Git use the editor of my choice for commits?

Question

I would prefer to write my commit messages in Vim, but it is opening them in Emacs.

How do I configure Git to always use Vim? Note that I want to do this globally,

Answer 1

For Textmate Users

This opens Textmate editor in when you want to edit your commits. Requires textmate command line tools to be installed.

git config --global core.editor "mate -w"