"Add "set -o vi" in your ~/.bashrc to make use the vi keybindings instead of the Emacs ones." Better to do this kind of thing in .inputrc, as:

set editing-mode vi

(or set editing-mode emacs) because any application that uses readline gets to use those settings. So for example you get command line editing in various command line apps. bash uses readline, so you'll get that. The python repl will give command line editing with .inputrc set as above.

  $ apt-rdepends -r libreadline6 |egrep -ve "^ " |wc -l
  8995

psql (postgresql) and mysql (mysql) are really handy with command line editing.

"'ctrl-x ctrl-e' opens an editor to work with long or complex command lines"

If you've set -o vi, or set editing-mode vi in .inputrc, then on a command line type:

  esc-v

(Escape key to get out of insert mode, then the 'v' key) That will open a full vim session for editing your complex command line.

  :wq

exits vim and gives your command to bash to execute.