Currently the default editor for Debian Linux is nano. This may be happy news for all nano fans out there. This means that any application on command line requiring such us crontab will open nano editor by default. If you prefer different editor such as vi or vim you can update your default settings with a following command:
this will output more options for you to choose from depending on what text editors are currently installed on your system.
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From the above you can see that in order yo change your default editor in Debian or Ubuntu Linux you simply choose selection number followed by ENTER.