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The Lessons of History
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11.2 History in a Nutshell

The C shell and bash can save copies of the previous command lines you type. Later, you can ask for a copy of some or all of a previous command line. That can save time and retyping.

This feature is called history substitution, and it's done when you type a string that starts with an exclamation point (!command). You can think of it like variable substitution ($varname) (6.8) or command substitution (`command`) (9.16): the shell replaces what you type (like !$) with something else (in this case, part or all of a previous command line).

Article 11.1 is an introduction to shell history. These articles show lots of ways to use history substitution:

One last note: putting the history number in your prompt (7.2) makes it easy to re-use commands that haven't scrolled off your screen.

- JP


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