Ubuntu:
sudo update-alternatives --config editor
There are 4 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/vim.basic 30 manual mode
4 /usr/bin/vim.tiny 10 manual mode
Press <enter> to keep the current choice[*], or type selection number:
Non-interactive solution for setting vim as default editor:
sudo update-alternatives --set editor /usr/bin/vim.basic
CentOS:
On CentOS, you can change this value by adding the following line to your ~/.bashrc:
$ export EDITOR=`which name_of_editor`
Source the file to implement the changes:
$ source ~/.bashrc
sudo update-alternatives --set editor /usr/bin/vim.basic