VIM
* i - go to insert mode starting before the current cursor position
* a - go to insert mode starting after the current cursor position
* o - go to insert mode after adding a new blank line after the current one
* :w - write file
* :q - quit
* :x - write file, then quit
* u - undo last edit
* ctrl-r - redo
* / - search forward in the file
* ? - search backward in the file