By mistake if an uncomfortable editor is set for crontab, we can change it with following command:
The output of above command will asks you to select any editor from list as shown below:
Select an editor. To change later, run ‘select-editor’.
2. /bin/nano <—- easiest
Choose 1-4 : 4
Since I am comfortable with vim chosen option 4, which will set my crontab editor as vim.tiny.
After choosing an option just press enter and open crontab, it should opened with the editor you have selected. In my case it opened with vim.tiny.
There is one more post in my blog which will set the crontab editor only for that session.
Here is the link to change crontab editor for current session only.