This post is older than a year. Consider some information might not be accurate anymore.
Using so many years vi or vim (vi improved) it is coming quite annoying that nano is the default editor. I understand that new users find it easier to use nano, but for all old school guys out there, this post describes how to set the vi or vim as default editor on deb based distributions like Debian, Ubuntu, etc.
Install vim with
sudo apt-get install vim
After this invoke sudo update-alternatives --config editor and set the editor to vim. Example
tan@cinhtau:~$ sudo update-alternatives --config editor
There are 5 choices for the alternative editor (providing /usr/bin/editor).
Selection Path Priority Status
------------------------------------------------------------
* 0 /bin/nano 40 auto mode
1 /bin/ed -100 manual mode
2 /bin/nano 40 manual mode
3 /usr/bin/mcedit 25 manual mode
4 /usr/bin/vim.basic 30 manual mode
5 /usr/bin/vim.tiny 10 manual mode
Press enter to keep the current choice[*], or type selection number: 4
update-alternatives: using /usr/bin/vim.basic to provide /usr/bin/editor (editor) in manual mode
