Command Line Editing
Setting the line edit mode: $set -o vi OR $set editing-mode vi
<TAB> complete last keystroke (not always available).
<ALT> ? Offer possible completions
<CTRL> a Move to the beginning of the line.
<CTRL> e Move to the end of the line.
<DEL> Delete the character to the left of the cursor.
<CTRL> l Clear the screen, reprinting the current line at the top.
<CTRL>_ Undo the last editing command.