History Expansion
=================
History expansion allows you to use words from previous command lines
in the command line you are typing. This simplifies spelling
corrections and the repetition of complicated commands or arguments.
Immediately before execution, each command is saved in the history list,
the size of which is controlled by the HISTSIZE parameter. The one
most recent command is always retained in any case. Each saved command
in the history list is called a history _event_ and is assigned a
number, beginning with 1 (one) when the shell starts up. The history
number that you may see in your prompt (see Note:Prompt Expansion)
is the number that is to be assigned to the _next_ command.