I ran into this with CentOS 5. Where the default editor for the system is set to nano!
I like vi and wanted to change the default to it.

1. login to the system
2. vi .bashrc
3. Add the following two lines to .bashrc
export EDITOR="vim" export VISUAL="vim"

1 2	export EDITOR="vim" export VISUAL="vim"

4. run the command, source .bashrc
5. A change to /etc/bashrc will make it a system wide change