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(bashref.info)History Interaction

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History Expansion
=================

   The History library provides a history expansion feature that is
similar to the history expansion provided by `csh'.  This section
describes the syntax used to manipulate the history information.

   History expansions introduce words from the history list into the
input stream, making it easy to repeat commands, insert the arguments
to a previous command into the current input line, or fix errors in
previous commands quickly.

   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 "event", and the portions of that line that are acted upon
are called "words".  Various "modifiers" are available to manipulate
the selected words.  The line is broken into words in the same fashion
that Bash does, so that several words surrounded by quotes are
considered one word.  History expansions are introduced by the
appearance of the history expansion character, which is `!' by default.
Only `\' and `'' may be used to escape the history expansion character.

   Several shell options settable with the `shopt' builtin (Note: Bash
Builtins) may be used to tailor the behavior of history expansion.
If the `histverify' shell option is enabled, and Readline is being
used, history substitutions are not immediately passed to the shell
parser.  Instead, the expanded line is reloaded into the Readline
editing buffer for further modification.  If Readline is being used,
and the `histreedit' shell option is enabled, a failed history
expansion will be reloaded into the Readline editing buffer for
correction.  The `-p' option to the `history' builtin command may be
used to see what a history expansion will do before using it.  The `-s'
option to the `history' builtin may be used to add commands to the end
of the history list without actually executing them, so that they are
available for subsequent recall.  This is most useful in conjunction
with Readline.

   The shell allows control of the various characters used by the
history expansion mechanism with the `histchars' variable.

Event Designators

How to specify which history line to use.

Word Designators

Specifying which words are of interest.

Modifiers

Modifying the results of substitution.