刚才在一台机器上打开 crontab -e，跳出来的编辑器是nano，太难使...
在debian下是使用 update-alternatives 命令修改默认编辑器。
先查看一下使用帮助
# update-alternatives --help
Usage: update-alternatives [<option> ...] <command>
--config <name>：show alternatives for the <name> group and ask the user to select which one to use.
修改默认编辑器，选择4 /usr/bin/vim.basic
# update-alternatives --config editor
There are 5 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/emacs23 0 manual mode
4 /usr/bin/vim.basic 30 manual mode
5 /usr/bin/vim.tiny 10 manual mode
Press enter to keep the current choice[*], or type selection number: 4
update-alternatives: using /usr/bin/vim.basic to provide /usr/bin/editor (editor) in manual mode
顺着提示看了一下对应的文件，都是软链接，最终指向 /usr/bin/vim.basic
# ls -l /usr/bin/editor
lrwxrwxrwx 1 root root 24 Dec 8 2015 /usr/bin/editor -> /etc/alternatives/editor
# ls -l /etc/alternatives/editor
lrwxrwxrwx 1 root root 18 Aug 14 15:00 /etc/alternatives/editor -> /usr/bin/vim.basic
另外，可以通过导出变量临时修改编辑器：
export EDITOR="/usr/bin/vim" ; crontab -e
这样，再次打开 crontab -e，跳出来的就是vim了。