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Summary Box
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 ($varname) (Section 35.9) or command substitution ('command') (Section 28.14): the shell replaces what you type (like !$) with something else (in this case, part or all of a previous command line).
Section 30.1 is an introduction to shell history. These articles show lots of ways to use history substitution:
We start with favorite uses from several contributors -- Section 30.3, Section 30.4, Section 30.5, and Section 30.6.
Section 30.8 starts with a quick introduction, then covers the full range of history substitutions with a series of examples that show the different kinds of things you can do with history.
(Back in Section 28.5 are examples of csh/tcsh and bash operators such as :r. Many of these can be used to edit history substitutions.)
See an easy way to repeat a set of csh/tcsh or bash commands in Section 30.9.
Each shell saves its own history. To pass a shell's history to another shell, see Section 30.12 and Section 30.13.
You don't have to use an exclamation point (!) for history. Section 30.15 shows how to use some other character.
The Korn shell does history in a different way. Section 30.14 introduces part of that: command-line editing in ksh and bash.
One last note: putting the history number in your prompt (Section 4.3) makes it easy to reuse commands that haven't scrolled off your screen.
-- JP
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| 30. The Use of History |  | 30.3. My Favorite Is !$ |
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