By default Ubuntu provides nano as it's command line editor. Personally I prefer VIM. Ubuntu provides a simple utility for changing the default editor. Run the following from the command line:
sudo update-alternatives --config editor
Ubuntu will return a dialog similar to the following, simply pick a number. Given these options, I would pick 3.
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: