In order to make vi the standard global default editor to edit crontab for example use this command for debian:

update-alternatives --config editor

and select vim.basic

follow it by

select-editor

or

change the symlink to the default editor manually:

rm /etc/alternatives/editor
ln -s /usr/bin/vi /etc/alternatives/editor

or

In order to make vi the global default editor in debian to edit crontab for example, either

vi /etc/bash.bashrc

and add this line at the end of the file:

export EDITOR=vi
export VISUAL=vi

To make this change only for an individual user (whereby ~ is the home directory of the current user or change it to the home directory of the user this should be changed for):

vi ~/.bashrc

and add this line at the end of the file:

export VISUAL=vi
export EDITOR=vi

In Debian 9, vi/vim has mouse support enabled by default. While this makes it easy to go to a different area of the file via mouse clicks, it causes copy&paste to fail and/or to behave weirdly.

To revert to the old behaviour, a local .vimrc file needs to be created. It can be empty (just containing a double quote sign which is a comment). When this file exists, the default config with mouse support (/usr/share/vim/vim80/defaults.vim) is not being loaded. Editing the defaults.vim file directly is discouraged as this will be overwritten by updates.

vi ~/.vimrc

add something to it. In the very least one double quoted line as a comment:

"placeholder as /usr/share/vim/vim80/defaults.vim is loaded if no ~/.vimrc exists

By default Debian installs vim-tiny which does not support syntax highlighting. To install all required modules for console use

apt-get install vim

then edit /etc/vim/vimrc

vi /etc/vim/vimrc

and enable syntax, dark backgrounds and remembering the previous cursor position by removing the double-quotes in front of the relevant lines like this:

" Vim5 and later versions support syntax highlighting. Uncommenting the next
" line enables syntax highlighting by default.
syntax on

" If using a dark background within the editing area and syntax highlighting
" turn on this option as well
set background=dark

Add the configuration to your local .vimrc file in your home directory for various sensible and convenient settings:

vi ~/.vimrc

"placeholder as /usr/share/vim/vim80/defaults.vim is loaded if no ~/.vimrc exists
syntax on
set tabstop=4       " The width of a TAB is set to 4.
                    " Still it is a \t. It is just that
                    " Vim will interpret it to be having
                    " a width of 4.

set shiftwidth=4    " Indents will have a width of 4

set softtabstop=4   " Sets the number of columns for a TAB

set expandtab       " Expand TABs to spaces

set nocompatible    " Fix telnet issues where cursor keys add A B etc

set mouse-=a        " Disable automatic visual mode when selecting with mouse

" Only do this part when compiled with support for autocommands.
if has("autocmd")

  " Enable file type detection.
  " Use the default filetype settings, so that mail gets 'tw' set to 72,
  " 'cindent' is on in C files, etc.
  " Also load indent files, to automatically do language-dependent indenting.
  " Revert with ":filetype off".
  filetype plugin indent on

  " Put these in an autocmd group, so that you can revert them with:
  " ":augroup vimStartup | au! | augroup END"
  augroup vimStartup
    au!

    " When editing a file, always jump to the last known cursor position.
    " Don't do it when the position is invalid or when inside an event handler
    " (happens when dropping a file on gvim).
    autocmd BufReadPost *
      \ if line("'\"") >= 1 && line("'\"") <= line("$") |
      \   exe "normal! g`\"" |
      \ endif

  augroup END

endif " has("autocmd")

VIM Cheat Sheet