n previous commands quickly.

   <p>History expansion takes place in two parts.  The first is to determine
which line from the history list should be used during substitution. 
The second is to select portions of that line for inclusion into the
current one.  The line selected from the history is called the
<dfn>event</dfn>, and the portions of that line that are acted upon are
called <dfn>words</dfn>.  Various <dfn>modifiers</dfn> are available to manipulate
the selected words.  The line is broken into wor