How to Change the Default Editor From Nano on Ubuntu Linux

Many of the utilities in Ubuntu Linux use a text editor to allow you to edit configuration options and files. An example of this is using the crontab command, which allows you to edit your cron jobs using the default editor.
It’s really easy to set the default editor using the update-alternatives command. Open up a terminal window and type in the following command:

sudo update-alternatives --config editor

Here’s an example of what you’ll see:

$ sudo update-alternatives –config editor
There are 5 alternatives which provide `editor’.
Selection Alternative
———————————————–
1 /usr/bin/vim
2 /bin/ed
*+ 3 /bin/nano
4 /usr/bin/vim.basic
5 /usr/bin/vim.tiny
Press enter to keep the default[*], or type selection number:

You can select the editor you want by just typing in the number. For example, if I want to change the default editor to vim, I would just hit the number 1.
You can test this out by typing in crontab -e to edit your cron file. You should see the editor that you chose, instead of the default.

Source from Howtogeek.com