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<div class="top-level-extent" id="Top">
<div class="nav-panel">
<p>
Next: <a href="#Using-History-Interactively" accesskey="n" rel="next">Using History Interactively</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Concept-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h1 class="top" id="GNU-History-Library"><span>GNU History Library<a class="copiable-link" href="#GNU-History-Library"> &para;</a></span></h1>

<p>This document describes the GNU History library, a programming tool that
provides a consistent user interface for recalling lines of previously
typed input.
</p>



<div class="element-contents" id="SEC_Contents">
<h2 class="contents-heading">Table of Contents</h2>

<div class="contents">

<ul class="toc-numbered-mark">
  <li><a id="toc-Using-History-Interactively-1" href="#Using-History-Interactively">1 Using History Interactively</a>
  <ul class="toc-numbered-mark">
    <li><a id="toc-History-Expansion-1" href="#History-Interaction">1.1 History Expansion</a>
    <ul class="toc-numbered-mark">
      <li><a id="toc-Event-Designators-1" href="#Event-Designators">1.1.1 Event Designators</a></li>
      <li><a id="toc-Word-Designators-1" href="#Word-Designators">1.1.2 Word Designators</a></li>
      <li><a id="toc-Modifiers-1" href="#Modifiers">1.1.3 Modifiers</a></li>
    </ul></li>
  </ul></li>
  <li><a id="toc-Programming-with-GNU-History-1" href="#Programming-with-GNU-History">2 Programming with GNU History</a>
  <ul class="toc-numbered-mark">
    <li><a id="toc-Introduction-to-History-1" href="#Introduction-to-History">2.1 Introduction to History</a></li>
    <li><a id="toc-History-Storage-1" href="#History-Storage">2.2 History Storage</a></li>
    <li><a id="toc-History-Functions-1" href="#History-Functions">2.3 History Functions</a>
    <ul class="toc-numbered-mark">
      <li><a id="toc-Initializing-History-and-State-Management-1" href="#Initializing-History-and-State-Management">2.3.1 Initializing History and State Management</a></li>
      <li><a id="toc-History-List-Management-1" href="#History-List-Management">2.3.2 History List Management</a></li>
      <li><a id="toc-Information-About-the-History-List-1" href="#Information-About-the-History-List">2.3.3 Information About the History List</a></li>
      <li><a id="toc-Moving-Around-the-History-List-1" href="#Moving-Around-the-History-List">2.3.4 Moving Around the History List</a></li>
      <li><a id="toc-Searching-the-History-List-1" href="#Searching-the-History-List">2.3.5 Searching the History List</a></li>
      <li><a id="toc-Managing-the-History-File-1" href="#Managing-the-History-File">2.3.6 Managing the History File</a></li>
      <li><a id="toc-History-Expansion-2" href="#History-Expansion">2.3.7 History Expansion</a></li>
    </ul></li>
    <li><a id="toc-History-Variables-1" href="#History-Variables">2.4 History Variables</a></li>
    <li><a id="toc-History-Programming-Example-1" href="#History-Programming-Example">2.5 History Programming Example</a></li>
  </ul></li>
  <li><a id="toc-GNU-Free-Documentation-License-1" href="#GNU-Free-Documentation-License">Appendix A GNU Free Documentation License</a></li>
  <li><a id="toc-Concept-Index-1" href="#Concept-Index" rel="index">Appendix B Concept Index</a></li>
  <li><a id="toc-Function-and-Variable-Index-1" href="#Function-and-Variable-Index" rel="index">Appendix C Function and Variable Index</a></li>
</ul>
</div>
</div>
<hr>
<div class="chapter-level-extent" id="Using-History-Interactively">
<div class="nav-panel">
<p>
Next: <a href="#Programming-with-GNU-History" accesskey="n" rel="next">Programming with GNU History</a>, Previous: <a href="#Top" accesskey="p" rel="prev">GNU History Library</a>, Up: <a href="#Top" accesskey="u" rel="up">GNU History Library</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Concept-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h2 class="chapter" id="Using-History-Interactively-1"><span>1 Using History Interactively<a class="copiable-link" href="#Using-History-Interactively-1"> &para;</a></span></h2>


<p>This chapter describes how to use the <small class="sc">GNU</small> History Library
interactively, from a user&rsquo;s standpoint.
It should be considered a user&rsquo;s guide.
For information on using the <small class="sc">GNU</small> History Library in your own programs,
see <a class="pxref" href="#Programming-with-GNU-History">Programming with GNU History</a>.
</p>


<ul class="mini-toc">
<li><a href="#History-Interaction" accesskey="1">History Expansion</a></li>
</ul>
<hr>
<div class="section-level-extent" id="History-Interaction">
<div class="nav-panel">
<p>
Up: <a href="#Using-History-Interactively" accesskey="u" rel="up">Using History Interactively</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Concept-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="History-Expansion-1"><span>1.1 History Expansion<a class="copiable-link" href="#History-Expansion-1"> &para;</a></span></h3>
<a class="index-entry-id" id="index-history-expansion"></a>

<p>The History library
provides a history expansion feature that is similar
to the history expansion provided by <code class="code">csh</code>
(also referred to as history substitution where appropriate).
This section describes the syntax used to manipulate the
history information.
</p>

<p>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.
</p>

<p>History expansion takes place in two parts.
The first is to determine
which entry from the history list should be used during substitution.
The second is to select portions of that entry to include into the
current one.
</p>
<p>The entry selected from the history is called the <em class="dfn">event</em>,
and the portions of that entry that are acted upon are <em class="dfn">words</em>.
Various <em class="dfn">modifiers</em> are available to manipulate the selected words.
The entry is split into words in the same fashion that Bash
does when reading input,
so that several words surrounded by quotes are considered one word.
The <em class="dfn">event designator</em> selects the event, the optional
<em class="dfn">word designator</em> selects words from the event, and
various optional <em class="dfn">modifiers</em> are available to manipulate the
selected words.
</p>
<p>History expansions are introduced by the appearance of the
history expansion character, which is &lsquo;<samp class="samp">!</samp>&rsquo; by default.
History expansions may appear anywhere in the input, but do not nest.
</p>
<p>History expansion implements shell-like quoting conventions:
a backslash can be used to remove the special handling for the next character;
single quotes enclose verbatim sequences of characters, and can be used to
inhibit history expansion;
and characters enclosed within double quotes may be subject to history
expansion, since backslash can escape the history expansion character,
but single quotes may not, since they are not treated specially within
double quotes.
</p>

<p>There is a special abbreviation for substitution, active when the
<var class="var">quick substitution</var> character
(default &lsquo;<samp class="samp">^</samp>&rsquo;)
is the first character on the line.
It selects the previous history list entry, using an event designator
equivalent to <code class="code">!!</code>,
and substitutes one string for another in that entry.
It is described below (see <a class="pxref" href="#Event-Designators">Event Designators</a>).
This is the only history expansion that does not begin with the history
expansion character.
</p>


<ul class="mini-toc">
<li><a href="#Event-Designators" accesskey="1">Event Designators</a></li>
<li><a href="#Word-Designators" accesskey="2">Word Designators</a></li>
<li><a href="#Modifiers" accesskey="3">Modifiers</a></li>
</ul>
<hr>
<div class="subsection-level-extent" id="Event-Designators">
<div class="nav-panel">
<p>
Next: <a href="#Word-Designators" accesskey="n" rel="next">Word Designators</a>, Up: <a href="#History-Interaction" accesskey="u" rel="up">History Expansion</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Concept-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Event-Designators-1"><span>1.1.1 Event Designators<a class="copiable-link" href="#Event-Designators-1"> &para;</a></span></h4>
<a class="index-entry-id" id="index-event-designators"></a>

<p>An event designator is a reference to an entry in the history list.
The event designator consists of the portion of the word beginning
with the history expansion character, and ending with the word designator
if one is present, or the end of the word.
Unless the reference is absolute, events are relative to the current
position in the history list.
<a class="index-entry-id" id="index-history-events"></a>
</p>
<dl class="table">
<dt><code class="code">!</code></dt>
<dd><p>Start a history substitution, except when followed by a space, tab,
the end of the line, or &lsquo;<samp class="samp">=</samp>&rsquo;.
</p>
</dd>
<dt><code class="code">!<var class="var">n</var></code></dt>
<dd><p>Refer to history list entry <var class="var">n</var>.
</p>
</dd>
<dt><code class="code">!-<var class="var">n</var></code></dt>
<dd><p>Refer to the history entry minus <var class="var">n</var>.
</p>
</dd>
<dt><code class="code">!!</code></dt>
<dd><p>Refer to the previous entry.
This is a synonym for &lsquo;<samp class="samp">!-1</samp>&rsquo;.
</p>
</dd>
<dt><code class="code">!<var class="var">string</var></code></dt>
<dd><p>Refer to the most recent command
preceding the current position in the history list
starting with <var class="var">string</var>.
</p>
</dd>
<dt><code class="code">!?<var class="var">string</var>[?]</code></dt>
<dd><p>Refer to the most recent command
preceding the current position in the history list
containing <var class="var">string</var>.
The trailing
&lsquo;<samp class="samp">?</samp>&rsquo; may be omitted if the <var class="var">string</var> is followed immediately by
a newline.
If <var class="var">string</var> is missing, this uses
the string from the most recent search;
it is an error if there is no previous search string.
</p>
</dd>
<dt><code class="code">^<var class="var">string1</var>^<var class="var">string2</var>^</code></dt>
<dd><p>Quick Substitution.
Repeat the last command, replacing <var class="var">string1</var> with <var class="var">string2</var>.
Equivalent to <code class="code">!!:s^<var class="var">string1</var>^<var class="var">string2</var>^</code>.
</p>
</dd>
<dt><code class="code">!#</code></dt>
<dd><p>The entire command line typed so far.
</p>
</dd>
</dl>

<hr>
</div>
<div class="subsection-level-extent" id="Word-Designators">
<div class="nav-panel">
<p>
Next: <a href="#Modifiers" accesskey="n" rel="next">Modifiers</a>, Previous: <a href="#Event-Designators" accesskey="p" rel="prev">Event Designators</a>, Up: <a href="#History-Interaction" accesskey="u" rel="up">History Expansion</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Concept-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Word-Designators-1"><span>1.1.2 Word Designators<a class="copiable-link" href="#Word-Designators-1"> &para;</a></span></h4>

<p>Word designators are used to select desired words from the event.
They are optional; if the word designator isn&rsquo;t supplied, the history
expansion uses the entire event.
A &lsquo;<samp class="samp">:</samp>&rsquo; separates the event specification from the word designator.
It may be omitted if the word designator begins with a &lsquo;<samp class="samp">^</samp>&rsquo;, &lsquo;<samp class="samp">$</samp>&rsquo;,
&lsquo;<samp class="samp">*</samp>&rsquo;, &lsquo;<samp class="samp">-</samp>&rsquo;, or &lsquo;<samp class="samp">%</samp>&rsquo;.
Words are numbered from the beginning of the line,
with the first word being denoted by 0 (zero).
That first word is usually the command word, and the arguments begin
with the second word.
Words are inserted into the current line separated by single spaces.
</p>
<p>For example,
</p>
<dl class="table">
<dt><code class="code">!!</code></dt>
<dd><p>designates the preceding command.
When you type this, the preceding command is repeated in toto.
</p>
</dd>
<dt><code class="code">!!:$</code></dt>
<dd><p>designates the last word of the preceding command.
This may be shortened to <code class="code">!$</code>.
</p>
</dd>
<dt><code class="code">!fi:2</code></dt>
<dd><p>designates the second argument of the most recent command starting with
the letters <code class="code">fi</code>.
</p></dd>
</dl>

<p>Here are the word designators:
</p>
<dl class="table">
<dt><code class="code">0 (zero)</code></dt>
<dd><p>The <code class="code">0</code>th word.
For the shell, and many other, applications, this is the command word.
</p>
</dd>
<dt><code class="code"><var class="var">n</var></code></dt>
<dd><p>The <var class="var">n</var>th word.
</p>
</dd>
<dt><code class="code">^</code></dt>
<dd><p>The first argument: word 1.
</p>
</dd>
<dt><code class="code">$</code></dt>
<dd><p>The last word.
This is usually the last argument, but expands to the
zeroth word if there is only one word in the line.
</p>
</dd>
<dt><code class="code">%</code></dt>
<dd><p>The first word matched by the most recent &lsquo;<samp class="samp">?<var class="var">string</var>?</samp>&rsquo; search,
if the search string begins with a character that is part of a word.
By default, searches begin at the end of each line and proceed to the
beginning, so the first word matched is the one closest to the end of
the line.
</p>
</dd>
<dt><code class="code"><var class="var">x</var>-<var class="var">y</var></code></dt>
<dd><p>A range of words; &lsquo;<samp class="samp">-<var class="var">y</var></samp>&rsquo; abbreviates &lsquo;<samp class="samp">0-<var class="var">y</var></samp>&rsquo;.
</p>
</dd>
<dt><code class="code">*</code></dt>
<dd><p>All of the words, except the <code class="code">0</code>th.
This is a synonym for &lsquo;<samp class="samp">1-$</samp>&rsquo;.
It is not an error to use &lsquo;<samp class="samp">*</samp>&rsquo; if there is just one word in the event;
it expands to the empty string in that case.
</p>
</dd>
<dt><code class="code"><var class="var">x</var>*</code></dt>
<dd><p>Abbreviates &lsquo;<samp class="samp"><var class="var">x</var>-$</samp>&rsquo;.
</p>
</dd>
<dt><code class="code"><var class="var">x</var>-</code></dt>
<dd><p>Abbreviates &lsquo;<samp class="samp"><var class="var">x</var>-$</samp>&rsquo; like &lsquo;<samp class="samp"><var class="var">x</var>*</samp>&rsquo;, but omits the last word.
If &lsquo;<samp class="samp">x</samp>&rsquo; is missing, it defaults to 0.
</p>
</dd>
</dl>

<p>If a word designator is supplied without an event specification, the
previous command is used as the event, equivalent to <code class="code">!!</code>. 
</p>
<hr>
</div>
<div class="subsection-level-extent" id="Modifiers">
<div class="nav-panel">
<p>
Previous: <a href="#Word-Designators" accesskey="p" rel="prev">Word Designators</a>, Up: <a href="#History-Interaction" accesskey="u" rel="up">History Expansion</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Concept-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Modifiers-1"><span>1.1.3 Modifiers<a class="copiable-link" href="#Modifiers-1"> &para;</a></span></h4>

<p>After the optional word designator, you can add a sequence of one or more
of the following modifiers, each preceded by a &lsquo;<samp class="samp">:</samp>&rsquo;.
These modify, or edit, the word or words selected from the history event.
</p>
<dl class="table">
<dt><code class="code">h</code></dt>
<dd><p>Remove a trailing filename component, leaving only the head.
</p>
</dd>
<dt><code class="code">t</code></dt>
<dd><p>Remove all leading filename components, leaving the tail.
</p>
</dd>
<dt><code class="code">r</code></dt>
<dd><p>Remove a trailing suffix of the form &lsquo;<samp class="samp">.<var class="var">suffix</var></samp>&rsquo;, leaving
the basename.
</p>
</dd>
<dt><code class="code">e</code></dt>
<dd><p>Remove all but the trailing suffix.
</p>
</dd>
<dt><code class="code">p</code></dt>
<dd><p>Print the new command but do not execute it.
</p>

</dd>
<dt><code class="code">s/<var class="var">old</var>/<var class="var">new</var>/</code></dt>
<dd><p>Substitute <var class="var">new</var> for the first occurrence of <var class="var">old</var> in the
event line.
Any character may be used as the delimiter in place of &lsquo;<samp class="samp">/</samp>&rsquo;.
The delimiter may be quoted in <var class="var">old</var> and <var class="var">new</var>
with a single backslash.
If &lsquo;<samp class="samp">&amp;</samp>&rsquo; appears in <var class="var">new</var>, it is replaced with <var class="var">old</var>.
A single backslash quotes the &lsquo;<samp class="samp">&amp;</samp>&rsquo; in <var class="var">old</var> and <var class="var">new</var>.
If <var class="var">old</var> is null, it is set to the last <var class="var">old</var>
substituted, or, if no previous history substitutions took place,
the last <var class="var">string</var>
in a !?<var class="var">string</var><code class="code">[?]</code>
search.
If <var class="var">new</var> is null, each matching <var class="var">old</var> is deleted.
The final delimiter is optional if it is the last
character on the input line.
</p>
</dd>
<dt><code class="code">&amp;</code></dt>
<dd><p>Repeat the previous substitution.
</p>
</dd>
<dt><code class="code">g</code></dt>
<dt><code class="code">a</code></dt>
<dd><p>Cause changes to be applied over the entire event line.
This is used in conjunction with
&lsquo;<samp class="samp">s</samp>&rsquo;, as in <code class="code">gs/<var class="var">old</var>/<var class="var">new</var>/</code>,
or with &lsquo;<samp class="samp">&amp;</samp>&rsquo;.
</p>
</dd>
<dt><code class="code">G</code></dt>
<dd><p>Apply the following &lsquo;<samp class="samp">s</samp>&rsquo; or &lsquo;<samp class="samp">&amp;</samp>&rsquo; modifier once to each word
in the event.
</p>
</dd>
</dl>

<hr>
</div>
</div>
</div>
<div class="chapter-level-extent" id="Programming-with-GNU-History">
<div class="nav-panel">
<p>
Next: <a href="#GNU-Free-Documentation-License" accesskey="n" rel="next">GNU Free Documentation License</a>, Previous: <a href="#Using-History-Interactively" accesskey="p" rel="prev">Using History Interactively</a>, Up: <a href="#Top" accesskey="u" rel="up">GNU History Library</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Concept-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h2 class="chapter" id="Programming-with-GNU-History-1"><span>2 Programming with GNU History<a class="copiable-link" href="#Programming-with-GNU-History-1"> &para;</a></span></h2>

<p>This chapter describes how to interface programs that you write
with the <small class="sc">GNU</small> History Library.
It should be considered a technical guide.
For information on the interactive use of <small class="sc">GNU</small> History,
see <a class="pxref" href="#Using-History-Interactively">Using History Interactively</a>.
</p>

<ul class="mini-toc">
<li><a href="#Introduction-to-History" accesskey="1">Introduction to History</a></li>
<li><a href="#History-Storage" accesskey="2">History Storage</a></li>
<li><a href="#History-Functions" accesskey="3">History Functions</a></li>
<li><a href="#History-Variables" accesskey="4">History Variables</a></li>
<li><a href="#History-Programming-Example" accesskey="5">History Programming Example</a></li>
</ul>
<hr>
<div class="section-level-extent" id="Introduction-to-History">
<div class="nav-panel">
<p>
Next: <a href="#History-Storage" accesskey="n" rel="next">History Storage</a>, Up: <a href="#Programming-with-GNU-History" accesskey="u" rel="up">Programming with GNU History</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Concept-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="Introduction-to-History-1"><span>2.1 Introduction to History<a class="copiable-link" href="#Introduction-to-History-1"> &para;</a></span></h3>

<p>Many programs read input from the user a line at a time.
The <small class="sc">GNU</small> History library is able to keep track of those lines,
associate arbitrary data with each line, and utilize information from
previous lines when composing new ones. 
</p>
<p>A programmer using the History library can use functions
to save commands on a history list,
associate arbitrary data with history list entries,
remove entries from the list,
search through the list for a line containing an arbitrary text string,
reference any entry in the list directly,
and read and write the history list from and to a file.
In addition, a history <em class="dfn">expansion</em> function
is available which provides for a consistent user interface across
different programs.
</p>
<p>Someone using programs written with the History library has the
benefit of a consistent user interface with a set of well-known
commands for manipulating the text of previous lines and using that text
in new commands.
The basic history manipulation commands are similar to
the history substitution provided by <code class="code">csh</code>.
</p>
<p>The programmer can also use the Readline library, which
includes some history manipulation by default, and has the added
advantage of command line editing.
</p>
<p>Before declaring any functions using any functionality the History
library provides in other code, an application writer should include
the file <code class="code">&lt;readline/history.h&gt;</code> in any file that uses the
History library&rsquo;s features.
It supplies declarations for all of the library&rsquo;s
public functions and variables,
and declares all of the public data structures.
</p>
<hr>
</div>
<div class="section-level-extent" id="History-Storage">
<div class="nav-panel">
<p>
Next: <a href="#History-Functions" accesskey="n" rel="next">History Functions</a>, Previous: <a href="#Introduction-to-History" accesskey="p" rel="prev">Introduction to History</a>, Up: <a href="#Programming-with-GNU-History" accesskey="u" rel="up">Programming with GNU History</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Concept-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="History-Storage-1"><span>2.2 History Storage<a class="copiable-link" href="#History-Storage-1"> &para;</a></span></h3>

<p>The history list is an array of history entries.
A history entry is declared as follows:
</p>
<div class="example">
<pre class="example-preformatted">typedef void *histdata_t;

typedef struct _hist_entry {
  char *line;
  char *timestamp;
  histdata_t data;
} HIST_ENTRY;
</pre></div>

<p>The history list itself might therefore be declared as
</p>
<div class="example">
<pre class="example-preformatted">HIST_ENTRY **the_history_list;
</pre></div>

<p>The state of the History library is encapsulated into a single structure:
</p>
<div class="example">
<pre class="example-preformatted">/*
 * A structure used to pass around the current state of the history.
 */
typedef struct _hist_state {
  HIST_ENTRY **entries; /* Pointer to the entries themselves. */
  int offset;           /* The location pointer within this array. */
  int length;           /* Number of elements within this array. */
  int size;             /* Number of slots allocated to this array. */
  int flags;
} HISTORY_STATE;
</pre></div>

<p>If the flags member includes <code class="code">HS_STIFLED</code>, the history has been
stifled (limited to a maximum number of entries).
</p>
<hr>
</div>
<div class="section-level-extent" id="History-Functions">
<div class="nav-panel">
<p>
Next: <a href="#History-Variables" accesskey="n" rel="next">History Variables</a>, Previous: <a href="#History-Storage" accesskey="p" rel="prev">History Storage</a>, Up: <a href="#Programming-with-GNU-History" accesskey="u" rel="up">Programming with GNU History</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Concept-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="History-Functions-1"><span>2.3 History Functions<a class="copiable-link" href="#History-Functions-1"> &para;</a></span></h3>

<p>This section describes the calling sequence for the various functions
exported by the <small class="sc">GNU</small> History library.
</p>

<ul class="mini-toc">
<li><a href="#Initializing-History-and-State-Management" accesskey="1">Initializing History and State Management</a></li>
<li><a href="#History-List-Management" accesskey="2">History List Management</a></li>
<li><a href="#Information-About-the-History-List" accesskey="3">Information About the History List</a></li>
<li><a href="#Moving-Around-the-History-List" accesskey="4">Moving Around the History List</a></li>
<li><a href="#Searching-the-History-List" accesskey="5">Searching the History List</a></li>
<li><a href="#Managing-the-History-File" accesskey="6">Managing the History File</a></li>
<li><a href="#History-Expansion" accesskey="7">History Expansion</a></li>
</ul>
<hr>
<div class="subsection-level-extent" id="Initializing-History-and-State-Management">
<div class="nav-panel">
<p>
Next: <a href="#History-List-Management" accesskey="n" rel="next">History List Management</a>, Up: <a href="#History-Functions" accesskey="u" rel="up">History Functions</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Concept-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Initializing-History-and-State-Management-1"><span>2.3.1 Initializing History and State Management<a class="copiable-link" href="#Initializing-History-and-State-Management-1"> &para;</a></span></h4>

<p>This section describes functions used to initialize and manage
the state of the History library when you want to use the history
functions in your program.
</p>
<dl class="first-deftypefn first-deftypefun-alias-first-deftypefn">
<dt class="deftypefn deftypefun-alias-deftypefn" id="index-using_005fhistory"><span class="category-def">Function: </span><span><code class="def-type">void</code> <strong class="def-name">using_history</strong> <code class="def-code-arguments">(void)</code><a class="copiable-link" href="#index-using_005fhistory"> &para;</a></span></dt>
<dd><p>Begin a session that will use the history functions.
This initializes the interactive variables.
</p></dd></dl>

<dl class="first-deftypefn first-deftypefun-alias-first-deftypefn">
<dt class="deftypefn deftypefun-alias-deftypefn" id="index-history_005fget_005fhistory_005fstate"><span class="category-def">Function: </span><span><code class="def-type">HISTORY_STATE *</code> <strong class="def-name">history_get_history_state</strong> <code class="def-code-arguments">(void)</code><a class="copiable-link" href="#index-history_005fget_005fhistory_005fstate"> &para;</a></span></dt>
<dd><p>Return a structure describing the current state of the input history.
</p></dd></dl>

<dl class="first-deftypefn first-deftypefun-alias-first-deftypefn">
<dt class="deftypefn deftypefun-alias-deftypefn" id="index-history_005fset_005fhistory_005fstate"><span class="category-def">Function: </span><span><code class="def-type">void</code> <strong class="def-name">history_set_history_state</strong> <code class="def-code-arguments">(HISTORY_STATE *state)</code><a class="copiable-link" href="#index-history_005fset_005fhistory_005fstate"> &para;</a></span></dt>
<dd><p>Set the state of the history list according to <var class="var">state</var>.
</p></dd></dl>

<hr>
</div>
<div class="subsection-level-extent" id="History-List-Management">
<div class="nav-panel">
<p>
Next: <a href="#Information-About-the-History-List" accesskey="n" rel="next">Information About the History List</a>, Previous: <a href="#Initializing-History-and-State-Management" accesskey="p" rel="prev">Initializing History and State Management</a>, Up: <a href="#History-Functions" accesskey="u" rel="up">History Functions</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Concept-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="History-List-Management-1"><span>2.3.2 History List Management<a class="copiable-link" href="#History-List-Management-1"> &para;</a></span></h4>

<p>These functions manage individual entries on the history list, or set
parameters managing the list itself.
</p>
<dl class="first-deftypefn first-deftypefun-alias-first-deftypefn">
<dt class="deftypefn deftypefun-alias-deftypefn" id="index-add_005fhistory"><span class="category-def">Function: </span><span><code class="def-type">void</code> <strong class="def-name">add_history</strong> <code class="def-code-arguments">(const char *string)</code><a class="copiable-link" href="#index-add_005fhistory"> &para;</a></span></dt>
<dd><p>Add <var class="var">string</var> to the end of the history list, and
set the associated data field (if any) to <code class="code">NULL</code>.
If the maximum number of history entries has been set using
<code class="code">stifle_history()</code>, and the new number of history entries
would exceed that maximum, this removes the oldest history entry.
</p></dd></dl>

<dl class="first-deftypefn first-deftypefun-alias-first-deftypefn">
<dt class="deftypefn deftypefun-alias-deftypefn" id="index-add_005fhistory_005ftime"><span class="category-def">Function: </span><span><code class="def-type">void</code> <strong class="def-name">add_history_time</strong> <code class="def-code-arguments">(const char *string)</code><a class="copiable-link" href="#index-add_005fhistory_005ftime"> &para;</a></span></dt>
<dd><p>Change the time stamp associated with the most recent history entry to
<var class="var">string</var>.
</p></dd></dl>

<dl class="first-deftypefn first-deftypefun-alias-first-deftypefn">
<dt class="deftypefn deftypefun-alias-deftypefn" id="index-remove_005fhistory"><span class="category-def">Function: </span><span><code class="def-type">HIST_ENTRY *</code> <strong class="def-name">remove_history</strong> <code class="def-code-arguments">(int which)</code><a class="copiable-link" href="#index-remove_005fhistory"> &para;</a></span></dt>
<dd><p>Remove the history entry at offset <var class="var">which</var> from the history list.
This returns the removed element so you can free the line, data,
and containing structure.
Since the data is private to your application, the History library
doesn&rsquo;t know how to free it, if necessary.
</p></dd></dl>

<dl class="first-deftypefn first-deftypefun-alias-first-deftypefn">
<dt class="deftypefn deftypefun-alias-deftypefn" id="index-free_005fhistory_005fentry"><span class="category-def">Function: </span><span><code class="def-type">histdata_t</code> <strong class="def-name">free_history_entry</strong> <code class="def-code-arguments">(HIST_ENTRY *histent)</code><a class="copiable-link" href="#index-free_005fhistory_005fentry"> &para;</a></span></dt>
<dd><p>Free the history entry <var class="var">histent</var> and any history library private
data associated with it.
Returns the application-specific data
so the caller can dispose of it.
</p></dd></dl>

<dl class="first-deftypefn first-deftypefun-alias-first-deftypefn">
<dt class="deftypefn deftypefun-alias-deftypefn" id="index-replace_005fhistory_005fentry"><span class="category-def">Function: </span><span><code class="def-type">HIST_ENTRY *</code> <strong class="def-name">replace_history_entry</strong> <code class="def-code-arguments">(int which, const char *line, histdata_t data)</code><a class="copiable-link" href="#index-replace_005fhistory_005fentry"> &para;</a></span></dt>
<dd><p>Make the history entry at offset <var class="var">which</var> have <var class="var">line</var> and <var class="var">data</var>.
This returns the old entry so the caller can dispose of any
application-specific data.
In the case of an invalid <var class="var">which</var>, this returns <code class="code">NULL</code>.
</p></dd></dl>

<dl class="first-deftypefn first-deftypefun-alias-first-deftypefn">
<dt class="deftypefn deftypefun-alias-deftypefn" id="index-clear_005fhistory"><span class="category-def">Function: </span><span><code class="def-type">void</code> <strong class="def-name">clear_history</strong> <code class="def-code-arguments">(void)</code><a class="copiable-link" href="#index-clear_005fhistory"> &para;</a></span></dt>
<dd><p>Clear the history list by deleting all the entries.
</p></dd></dl>

<dl class="first-deftypefn first-deftypefun-alias-first-deftypefn">
<dt class="deftypefn deftypefun-alias-deftypefn" id="index-stifle_005fhistory"><span class="category-def">Function: </span><span><code class="def-type">void</code> <strong class="def-name">stifle_history</strong> <code class="def-code-arguments">(int max)</code><a class="copiable-link" href="#index-stifle_005fhistory"> &para;</a></span></dt>
<dd><p>Stifle the history list, remembering only the last <var class="var">max</var> entries.
The history list will contain only <var class="var">max</var> entries at a time.
</p></dd></dl>

<dl class="first-deftypefn first-deftypefun-alias-first-deftypefn">
<dt class="deftypefn deftypefun-alias-deftypefn" id="index-unstifle_005fhistory"><span class="category-def">Function: </span><span><code class="def-type">int</code> <strong class="def-name">unstifle_history</strong> <code class="def-code-arguments">(void)</code><a class="copiable-link" href="#index-unstifle_005fhistory"> &para;</a></span></dt>
<dd><p>Stop stifling the history.
This returns the previously-set maximum number of history
entries (as set by <code class="code">stifle_history()</code>).
The value is positive if the history was stifled, negative if it wasn&rsquo;t.
</p></dd></dl>

<dl class="first-deftypefn first-deftypefun-alias-first-deftypefn">
<dt class="deftypefn deftypefun-alias-deftypefn" id="index-history_005fis_005fstifled"><span class="category-def">Function: </span><span><code class="def-type">int</code> <strong class="def-name">history_is_stifled</strong> <code class="def-code-arguments">(void)</code><a class="copiable-link" href="#index-history_005fis_005fstifled"> &para;</a></span></dt>
<dd><p>Returns non-zero if the history is stifled, zero if it is not.
</p></dd></dl>

<hr>
</div>
<div class="subsection-level-extent" id="Information-About-the-History-List">
<div class="nav-panel">
<p>
Next: <a href="#Moving-Around-the-History-List" accesskey="n" rel="next">Moving Around the History List</a>, Previous: <a href="#History-List-Management" accesskey="p" rel="prev">History List Management</a>, Up: <a href="#History-Functions" accesskey="u" rel="up">History Functions</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Concept-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Information-About-the-History-List-1"><span>2.3.3 Information About the History List<a class="copiable-link" href="#Information-About-the-History-List-1"> &para;</a></span></h4>

<p>These functions return information about the entire history list or
individual list entries.
</p>
<dl class="first-deftypefn first-deftypefun-alias-first-deftypefn">
<dt class="deftypefn deftypefun-alias-deftypefn" id="index-history_005flist"><span class="category-def">Function: </span><span><code class="def-type">HIST_ENTRY **</code> <strong class="def-name">history_list</strong> <code class="def-code-arguments">(void)</code><a class="copiable-link" href="#index-history_005flist"> &para;</a></span></dt>
<dd><p>Return a <code class="code">NULL</code> terminated array of <code class="code">HIST_ENTRY *</code> which is the
current input history.
Element 0 of this list is the beginning of time.
Return <code class="code">NULL</code> if there is no history.
</p></dd></dl>

<dl class="first-deftypefn first-deftypefun-alias-first-deftypefn">
<dt class="deftypefn deftypefun-alias-deftypefn" id="index-where_005fhistory"><span class="category-def">Function: </span><span><code class="def-type">int</code> <strong class="def-name">where_history</strong> <code class="def-code-arguments">(void)</code><a class="copiable-link" href="#index-where_005fhistory"> &para;</a></span></dt>
<dd><p>Return the offset of the current history entry.
</p></dd></dl>

<dl class="first-deftypefn first-deftypefun-alias-first-deftypefn">
<dt class="deftypefn deftypefun-alias-deftypefn" id="index-current_005fhistory"><span class="category-def">Function: </span><span><code class="def-type">HIST_ENTRY *</code> <strong class="def-name">current_history</strong> <code class="def-code-arguments">(void)</code><a class="copiable-link" href="#index-current_005fhistory"> &para;</a></span></dt>
<dd><p>Return the history entry at the current position, as determined by
<code class="code">where_history()</code>.
If there is no entry there, return <code class="code">NULL</code>.
</p></dd></dl>

<dl class="first-deftypefn first-deftypefun-alias-first-deftypefn">
<dt class="deftypefn deftypefun-alias-deftypefn" id="index-history_005fget"><span class="category-def">Function: </span><span><code class="def-type">HIST_ENTRY *</code> <strong class="def-name">history_get</strong> <code class="def-code-arguments">(int offset)</code><a class="copiable-link" href="#index-history_005fget"> &para;</a></span></dt>
<dd><p>Return the history entry at position <var class="var">offset</var>.
The range of valid
values of <var class="var">offset</var> starts at <code class="code">history_base</code> and ends at
<var class="var">history_length</var> - 1 (see <a class="pxref" href="#History-Variables">History Variables</a>).
If there is no entry there, or if <var class="var">offset</var> is outside the valid
range, return <code class="code">NULL</code>.
</p></dd></dl>

<dl class="first-deftypefn first-deftypefun-alias-first-deftypefn">
<dt class="deftypefn deftypefun-alias-deftypefn" id="index-history_005fget_005ftime"><span class="category-def">Function: </span><span><code class="def-type">time_t</code> <strong class="def-name">history_get_time</strong> <code class="def-code-arguments">(HIST_ENTRY *entry)</code><a class="copiable-link" href="#index-history_005fget_005ftime"> &para;</a></span></dt>
<dd><p>Return the time stamp associated with the history entry <var class="var">entry</var>.
If the timestamp is missing or invalid, return 0.
</p></dd></dl>

<dl class="first-deftypefn first-deftypefun-alias-first-deftypefn">
<dt class="deftypefn deftypefun-alias-deftypefn" id="index-history_005ftotal_005fbytes"><span class="category-def">Function: </span><span><code class="def-type">int</code> <strong class="def-name">history_total_bytes</strong> <code class="def-code-arguments">(void)</code><a class="copiable-link" href="#index-history_005ftotal_005fbytes"> &para;</a></span></dt>
<dd><p>Return the number of bytes that the primary history entries are using.
This function returns the sum of the lengths of all the lines in the
history.
</p></dd></dl>

<hr>
</div>
<div class="subsection-level-extent" id="Moving-Around-the-History-List">
<div class="nav-panel">
<p>
Next: <a href="#Searching-the-History-List" accesskey="n" rel="next">Searching the History List</a>, Previous: <a href="#Information-About-the-History-List" accesskey="p" rel="prev">Information About the History List</a>, Up: <a href="#History-Functions" accesskey="u" rel="up">History Functions</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Concept-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Moving-Around-the-History-List-1"><span>2.3.4 Moving Around the History List<a class="copiable-link" href="#Moving-Around-the-History-List-1"> &para;</a></span></h4>

<p>These functions allow the current index into the history list to be
set or changed.
</p>
<dl class="first-deftypefn first-deftypefun-alias-first-deftypefn">
<dt class="deftypefn deftypefun-alias-deftypefn" id="index-history_005fset_005fpos"><span class="category-def">Function: </span><span><code class="def-type">int</code> <strong class="def-name">history_set_pos</strong> <code class="def-code-arguments">(int pos)</code><a class="copiable-link" href="#index-history_005fset_005fpos"> &para;</a></span></dt>
<dd><p>Set the current history offset to <var class="var">pos</var>, an absolute index
into the list.
Returns 1 on success, 0 if <var class="var">pos</var> is less than zero or greater
than the number of history entries.
</p></dd></dl>

<dl class="first-deftypefn first-deftypefun-alias-first-deftypefn">
<dt class="deftypefn deftypefun-alias-deftypefn" id="index-previous_005fhistory"><span class="category-def">Function: </span><span><code class="def-type">HIST_ENTRY *</code> <strong class="def-name">previous_history</strong> <code class="def-code-arguments">(void)</code><a class="copiable-link" href="#index-previous_005fhistory"> &para;</a></span></dt>
<dd><p>Back up the current history offset to the previous history entry, and
return a pointer to that entry.
If there is no previous entry, return <code class="code">NULL</code>.
</p></dd></dl>

<dl class="first-deftypefn first-deftypefun-alias-first-deftypefn">
<dt class="deftypefn deftypefun-alias-deftypefn" id="index-next_005fhistory"><span class="category-def">Function: </span><span><code class="def-type">HIST_ENTRY *</code> <strong class="def-name">next_history</strong> <code class="def-code-arguments">(void)</code><a class="copiable-link" href="#index-next_005fhistory"> &para;</a></span></dt>
<dd><p>If the current history offset refers to a valid history entry,
increment the current history offset.
If the possibly-incremented history offset refers to a valid history
entry, return a pointer to that entry;
otherwise, return <code class="code">NULL</code>.
</p></dd></dl>

<hr>
</div>
<div class="subsection-level-extent" id="Searching-the-History-List">
<div class="nav-panel">
<p>
Next: <a href="#Managing-the-History-File" accesskey="n" rel="next">Managing the History File</a>, Previous: <a href="#Moving-Around-the-History-List" accesskey="p" rel="prev">Moving Around the History List</a>, Up: <a href="#History-Functions" accesskey="u" rel="up">History Functions</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Concept-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Searching-the-History-List-1"><span>2.3.5 Searching the History List<a class="copiable-link" href="#Searching-the-History-List-1"> &para;</a></span></h4>
<a class="index-entry-id" id="index-History-Searching"></a>

<p>These functions search the history list for entries containing
a specific string.
Searching may be performed both forward and backward
from the current history position.
The search may be <em class="dfn">anchored</em>,
meaning that the string must match at the beginning of a history entry.
<a class="index-entry-id" id="index-anchored-search"></a>
</p>
<dl class="first-deftypefn first-deftypefun-alias-first-deftypefn">
<dt class="deftypefn deftypefun-alias-deftypefn" id="index-history_005fsearch"><span class="category-def">Function: </span><span><code class="def-type">int</code> <strong class="def-name">history_search</strong> <code class="def-code-arguments">(const char *string, int direction)</code><a class="copiable-link" href="#index-history_005fsearch"> &para;</a></span></dt>
<dd><p>Search the history for <var class="var">string</var>, starting at the current history offset.
If <var class="var">direction</var> is less than 0, then the search is through
previous entries, otherwise through subsequent entries.
If <var class="var">string</var> is found, then the current history index is set to
that history entry, and <code class="code">history_search</code>
returns the offset in the line of the entry where
<var class="var">string</var> was found.
Otherwise, nothing is changed, and this returns -1.
</p></dd></dl>

<dl class="first-deftypefn first-deftypefun-alias-first-deftypefn">
<dt class="deftypefn deftypefun-alias-deftypefn" id="index-history_005fsearch_005fprefix"><span class="category-def">Function: </span><span><code class="def-type">int</code> <strong class="def-name">history_search_prefix</strong> <code class="def-code-arguments">(const char *string, int direction)</code><a class="copiable-link" href="#index-history_005fsearch_005fprefix"> &para;</a></span></dt>
<dd><p>Search the history for <var class="var">string</var>, starting at the current history
offset.
The search is anchored: matching history entries must begin with <var class="var">string</var>.
If <var class="var">direction</var> is less than 0, then the search is
through previous entries, otherwise through subsequent entries.
If <var class="var">string</var> is found, then the current history index is set to
that entry, and the return value is 0. 
Otherwise, nothing is changed, and this returns -1. 
</p></dd></dl>

<dl class="first-deftypefn first-deftypefun-alias-first-deftypefn">
<dt class="deftypefn deftypefun-alias-deftypefn" id="index-history_005fsearch_005fpos"><span class="category-def">Function: </span><span><code class="def-type">int</code> <strong class="def-name">history_search_pos</strong> <code class="def-code-arguments">(const char *string, int direction, int pos)</code><a class="copiable-link" href="#index-history_005fsearch_005fpos"> &para;</a></span></dt>
<dd><p>Search for <var class="var">string</var> in the history list, starting at <var class="var">pos</var>, an
absolute index into the list.
If <var class="var">direction</var> is negative, the search
proceeds backward from <var class="var">pos</var>, otherwise forward.
Returns the index in the history list
of the history element where <var class="var">string</var> was
found, or -1 otherwise.
</p></dd></dl>

<hr>
</div>
<div class="subsection-level-extent" id="Managing-the-History-File">
<div class="nav-panel">
<p>
Next: <a href="#History-Expansion" accesskey="n" rel="next">History Expansion</a>, Previous: <a href="#Searching-the-History-List" accesskey="p" rel="prev">Searching the History List</a>, Up: <a href="#History-Functions" accesskey="u" rel="up">History Functions</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Concept-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="Managing-the-History-File-1"><span>2.3.6 Managing the History File<a class="copiable-link" href="#Managing-the-History-File-1"> &para;</a></span></h4>

<p>The History library can read the history from and write it to a file.
This section documents the functions for managing a history file.
</p>
<dl class="first-deftypefn first-deftypefun-alias-first-deftypefn">
<dt class="deftypefn deftypefun-alias-deftypefn" id="index-read_005fhistory"><span class="category-def">Function: </span><span><code class="def-type">int</code> <strong class="def-name">read_history</strong> <code class="def-code-arguments">(const char *filename)</code><a class="copiable-link" href="#index-read_005fhistory"> &para;</a></span></dt>
<dd><p>Add the contents of <var class="var">filename</var> to the history list, one entry
at a time.
If <var class="var">filename</var> is <code class="code">NULL</code>, this reads from <samp class="file">~/.history</samp>,
if it exists.
This attempts to determine whether the history file includes timestamp
information, and assigns timestamps to the history entries it reads
if so.
Returns 0 if successful, or <code class="code">errno</code> if not.
</p></dd></dl>

<dl class="first-deftypefn first-deftypefun-alias-first-deftypefn">
<dt class="deftypefn deftypefun-alias-deftypefn" id="index-read_005fhistory_005frange"><span class="category-def">Function: </span><span><code class="def-type">int</code> <strong class="def-name">read_history_range</strong> <code class="def-code-arguments">(const char *filename, int from, int to)</code><a class="copiable-link" href="#index-read_005fhistory_005frange"> &para;</a></span></dt>
<dd><p>Read a range of lines from <var class="var">filename</var>, adding them to the history list.
Start reading at line <var class="var">from</var> and end at <var class="var">to</var>.
If <var class="var">from</var> is zero, start at the beginning.
If <var class="var">to</var> is less than <var class="var">from</var>, this reads until the end of the file.
This attempts to determine whether the history file includes timestamp
information, and assigns timestamps to the history entries it reads
if so.
If <var class="var">filename</var> is <code class="code">NULL</code>, this reads from <samp class="file">~/.history</samp>,
if it exists.
Returns 0 if successful, or <code class="code">errno</code> if not.
</p></dd></dl>

<dl class="first-deftypefn first-deftypefun-alias-first-deftypefn">
<dt class="deftypefn deftypefun-alias-deftypefn" id="index-write_005fhistory"><span class="category-def">Function: </span><span><code class="def-type">int</code> <strong class="def-name">write_history</strong> <code class="def-code-arguments">(const char *filename)</code><a class="copiable-link" href="#index-write_005fhistory"> &para;</a></span></dt>
<dd><p>Write the current history to <var class="var">filename</var>, overwriting <var class="var">filename</var>
if necessary.
This writes timestamp information if the
<code class="code">history_write_timestamps</code> variable is set to a non-zero value.
If <var class="var">filename</var> is <code class="code">NULL</code>, then write the history list to
<samp class="file">~/.history</samp>.
Returns 0 on success, or <code class="code">errno</code> on a read or write error.
</p></dd></dl>

<dl class="first-deftypefn first-deftypefun-alias-first-deftypefn">
<dt class="deftypefn deftypefun-alias-deftypefn" id="index-append_005fhistory"><span class="category-def">Function: </span><span><code class="def-type">int</code> <strong class="def-name">append_history</strong> <code class="def-code-arguments">(int nelements, const char *filename)</code><a class="copiable-link" href="#index-append_005fhistory"> &para;</a></span></dt>
<dd><p>Append the last <var class="var">nelements</var> of the history list to <var class="var">filename</var>.
This writes timestamp information if the
<code class="code">history_write_timestamps</code> variable is set to a non-zero value.
If <var class="var">filename</var> is <code class="code">NULL</code>, then append to <samp class="file">~/.history</samp>.
Returns 0 on success, or <code class="code">errno</code> on a read or write error.
</p></dd></dl>

<dl class="first-deftypefn first-deftypefun-alias-first-deftypefn">
<dt class="deftypefn deftypefun-alias-deftypefn" id="index-history_005ftruncate_005ffile"><span class="category-def">Function: </span><span><code class="def-type">int</code> <strong class="def-name">history_truncate_file</strong> <code class="def-code-arguments">(const char *filename, int nlines)</code><a class="copiable-link" href="#index-history_005ftruncate_005ffile"> &para;</a></span></dt>
<dd><p>Truncate the history file <var class="var">filename</var>, leaving only the last
<var class="var">nlines</var> lines.
If <var class="var">filename</var> is <code class="code">NULL</code>, this truncates <samp class="file">~/.history</samp>.
Returns 0 on success, or <code class="code">errno</code> on failure.
</p></dd></dl>

<hr>
</div>
<div class="subsection-level-extent" id="History-Expansion">
<div class="nav-panel">
<p>
Previous: <a href="#Managing-the-History-File" accesskey="p" rel="prev">Managing the History File</a>, Up: <a href="#History-Functions" accesskey="u" rel="up">History Functions</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Concept-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h4 class="subsection" id="History-Expansion-2"><span>2.3.7 History Expansion<a class="copiable-link" href="#History-Expansion-2"> &para;</a></span></h4>

<p>These functions implement history expansion.
</p>
<dl class="first-deftypefn first-deftypefun-alias-first-deftypefn">
<dt class="deftypefn deftypefun-alias-deftypefn" id="index-history_005fexpand"><span class="category-def">Function: </span><span><code class="def-type">int</code> <strong class="def-name">history_expand</strong> <code class="def-code-arguments">(const char *string, char **output)</code><a class="copiable-link" href="#index-history_005fexpand"> &para;</a></span></dt>
<dd><p>Expand <var class="var">string</var>, placing the result into <var class="var">output</var>, a pointer
to a string (see <a class="pxref" href="#History-Interaction">History Expansion</a>).
Returns:
</p><dl class="table">
<dt><code class="code">0</code></dt>
<dd><p>If no expansions took place (or, if the only change in
the text was the removal of escape characters preceding the history expansion
character);
</p></dd>
<dt><code class="code">1</code></dt>
<dd><p>if expansions did take place;
</p></dd>
<dt><code class="code">-1</code></dt>
<dd><p>if there was an error in expansion;
</p></dd>
<dt><code class="code">2</code></dt>
<dd><p>if the returned line should be displayed, but not executed,
as with the <code class="code">:p</code> modifier (see <a class="pxref" href="#Modifiers">Modifiers</a>).
</p></dd>
</dl>

<p>If an error occurred during expansion,
then <var class="var">output</var> contains a descriptive error message.
</p></dd></dl>

<dl class="first-deftypefn first-deftypefun-alias-first-deftypefn">
<dt class="deftypefn deftypefun-alias-deftypefn" id="index-get_005fhistory_005fevent"><span class="category-def">Function: </span><span><code class="def-type">char *</code> <strong class="def-name">get_history_event</strong> <code class="def-code-arguments">(const char *string, int *cindex, int qchar)</code><a class="copiable-link" href="#index-get_005fhistory_005fevent"> &para;</a></span></dt>
<dd><p>Returns the text of the history event beginning at <var class="var">string</var> +
<var class="var">*cindex</var>.
Modifies <var class="var">*cindex</var> to point to after the event specifier.
At function entry, <var class="var">cindex</var> points to the index into <var class="var">string</var>
where the history event specification begins.
<var class="var">qchar</var>
is a character that is allowed to end the event specification in addition
to the &ldquo;normal&rdquo; terminating characters.
</p></dd></dl>

<dl class="first-deftypefn first-deftypefun-alias-first-deftypefn">
<dt class="deftypefn deftypefun-alias-deftypefn" id="index-history_005ftokenize"><span class="category-def">Function: </span><span><code class="def-type">char **</code> <strong class="def-name">history_tokenize</strong> <code class="def-code-arguments">(const char *string)</code><a class="copiable-link" href="#index-history_005ftokenize"> &para;</a></span></dt>
<dd><p>Return an array of tokens parsed out of <var class="var">string</var>, much as the
shell might.
The tokens are split on the characters in the
<var class="var">history_word_delimiters</var> variable,
and shell quoting conventions are obeyed as described below.
</p></dd></dl>

<dl class="first-deftypefn first-deftypefun-alias-first-deftypefn">
<dt class="deftypefn deftypefun-alias-deftypefn" id="index-history_005farg_005fextract"><span class="category-def">Function: </span><span><code class="def-type">char *</code> <strong class="def-name">history_arg_extract</strong> <code class="def-code-arguments">(int first, int last, const char *string)</code><a class="copiable-link" href="#index-history_005farg_005fextract"> &para;</a></span></dt>
<dd><p>Extract a string segment consisting of the <var class="var">first</var> through <var class="var">last</var>
arguments present in <var class="var">string</var>.
This splits <var class="var">string</var> into arguments using <code class="code">history_tokenize</code>.
</p></dd></dl>

<hr>
</div>
</div>
<div class="section-level-extent" id="History-Variables">
<div class="nav-panel">
<p>
Next: <a href="#History-Programming-Example" accesskey="n" rel="next">History Programming Example</a>, Previous: <a href="#History-Functions" accesskey="p" rel="prev">History Functions</a>, Up: <a href="#Programming-with-GNU-History" accesskey="u" rel="up">Programming with GNU History</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Concept-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="History-Variables-1"><span>2.4 History Variables<a class="copiable-link" href="#History-Variables-1"> &para;</a></span></h3>

<p>This section describes the externally-visible variables exported by
the <small class="sc">GNU</small> History Library.
</p>
<dl class="first-deftypevr first-deftypevar-alias-first-deftypevr">
<dt class="deftypevr deftypevar-alias-deftypevr" id="index-history_005fbase"><span class="category-def">Variable: </span><span><code class="def-type">int</code> <strong class="def-name">history_base</strong><a class="copiable-link" href="#index-history_005fbase"> &para;</a></span></dt>
<dd><p>The logical offset of the first entry in the history list.
</p></dd></dl>

<dl class="first-deftypevr first-deftypevar-alias-first-deftypevr">
<dt class="deftypevr deftypevar-alias-deftypevr" id="index-history_005flength"><span class="category-def">Variable: </span><span><code class="def-type">int</code> <strong class="def-name">history_length</strong><a class="copiable-link" href="#index-history_005flength"> &para;</a></span></dt>
<dd><p>The number of entries currently stored in the history list.
</p></dd></dl>

<dl class="first-deftypevr first-deftypevar-alias-first-deftypevr">
<dt class="deftypevr deftypevar-alias-deftypevr" id="index-history_005fmax_005fentries"><span class="category-def">Variable: </span><span><code class="def-type">int</code> <strong class="def-name">history_max_entries</strong><a class="copiable-link" href="#index-history_005fmax_005fentries"> &para;</a></span></dt>
<dd><p>The maximum number of history entries.
This must be changed using <code class="code">stifle_history()</code>.
</p></dd></dl>

<dl class="first-deftypevr first-deftypevar-alias-first-deftypevr">
<dt class="deftypevr deftypevar-alias-deftypevr" id="index-history_005fwrite_005ftimestamps"><span class="category-def">Variable: </span><span><code class="def-type">int</code> <strong class="def-name">history_write_timestamps</strong><a class="copiable-link" href="#index-history_005fwrite_005ftimestamps"> &para;</a></span></dt>
<dd><p>If non-zero, timestamps are written to the history file, so they can be
preserved between sessions.
The default value is 0, meaning that timestamps are not saved.
</p>
<p>The current timestamp format uses the value of <var class="var">history_comment_char</var>
to delimit timestamp entries in the history file.
If that variable does not have a value (the default),
the history library will not write timestamps.
</p></dd></dl>

<dl class="first-deftypevr first-deftypevar-alias-first-deftypevr">
<dt class="deftypevr deftypevar-alias-deftypevr" id="index-history_005fexpansion_005fchar"><span class="category-def">Variable: </span><span><code class="def-type">char</code> <strong class="def-name">history_expansion_char</strong><a class="copiable-link" href="#index-history_005fexpansion_005fchar"> &para;</a></span></dt>
<dd><p>The character that introduces a history event.
The default is &lsquo;<samp class="samp">!</samp>&rsquo;.
Setting this to 0 inhibits history expansion.
</p></dd></dl>

<dl class="first-deftypevr first-deftypevar-alias-first-deftypevr">
<dt class="deftypevr deftypevar-alias-deftypevr" id="index-history_005fsubst_005fchar"><span class="category-def">Variable: </span><span><code class="def-type">char</code> <strong class="def-name">history_subst_char</strong><a class="copiable-link" href="#index-history_005fsubst_005fchar"> &para;</a></span></dt>
<dd><p>The character that invokes word substitution if found at the start of
a line.
The default is &lsquo;<samp class="samp">^</samp>&rsquo;.
</p></dd></dl>

<dl class="first-deftypevr first-deftypevar-alias-first-deftypevr">
<dt class="deftypevr deftypevar-alias-deftypevr" id="index-history_005fcomment_005fchar"><span class="category-def">Variable: </span><span><code class="def-type">char</code> <strong class="def-name">history_comment_char</strong><a class="copiable-link" href="#index-history_005fcomment_005fchar"> &para;</a></span></dt>
<dd><p>During tokenization, if this character appears as the first character
of a word, then it and all subsequent characters up to a newline are
ignored, suppressing history expansion for the remainder of the line.
This is disabled by default.
</p></dd></dl>

<dl class="first-deftypevr first-deftypevar-alias-first-deftypevr">
<dt class="deftypevr deftypevar-alias-deftypevr" id="index-history_005fword_005fdelimiters"><span class="category-def">Variable: </span><span><code class="def-type">char *</code> <strong class="def-name">history_word_delimiters</strong><a class="copiable-link" href="#index-history_005fword_005fdelimiters"> &para;</a></span></dt>
<dd><p>The characters that separate tokens for <code class="code">history_tokenize()</code>.
The default value is <code class="code">&quot; \t\n()&lt;&gt;;&amp;|&quot;</code>.
</p></dd></dl>

<dl class="first-deftypevr first-deftypevar-alias-first-deftypevr">
<dt class="deftypevr deftypevar-alias-deftypevr" id="index-history_005fsearch_005fdelimiter_005fchars"><span class="category-def">Variable: </span><span><code class="def-type">char *</code> <strong class="def-name">history_search_delimiter_chars</strong><a class="copiable-link" href="#index-history_005fsearch_005fdelimiter_005fchars"> &para;</a></span></dt>
<dd><p>The list of additional characters which can delimit a history search
string, in addition to space, TAB, &lsquo;<samp class="samp">:</samp>&rsquo; and &lsquo;<samp class="samp">?</samp>&rsquo; in the case of
a substring search.
The default is empty.
</p></dd></dl>

<dl class="first-deftypevr first-deftypevar-alias-first-deftypevr">
<dt class="deftypevr deftypevar-alias-deftypevr" id="index-history_005fno_005fexpand_005fchars"><span class="category-def">Variable: </span><span><code class="def-type">char *</code> <strong class="def-name">history_no_expand_chars</strong><a class="copiable-link" href="#index-history_005fno_005fexpand_005fchars"> &para;</a></span></dt>
<dd><p>The list of characters which inhibit history expansion if found immediately
following <var class="var">history_expansion_char</var>.
The default is space, tab, newline, carriage return, and &lsquo;<samp class="samp">=</samp>&rsquo;.
</p></dd></dl>

<dl class="first-deftypevr first-deftypevar-alias-first-deftypevr">
<dt class="deftypevr deftypevar-alias-deftypevr" id="index-history_005fquotes_005finhibit_005fexpansion"><span class="category-def">Variable: </span><span><code class="def-type">int</code> <strong class="def-name">history_quotes_inhibit_expansion</strong><a class="copiable-link" href="#index-history_005fquotes_005finhibit_005fexpansion"> &para;</a></span></dt>
<dd><p>If non-zero, the history expansion code implements shell-like quoting:
single-quoted words are not scanned for the history expansion
character or the history comment character, and double-quoted words may
have history expansion performed, since single quotes are not special
within double quotes.
The default value is 0.
</p></dd></dl>

<dl class="first-deftypevr first-deftypevar-alias-first-deftypevr">
<dt class="deftypevr deftypevar-alias-deftypevr" id="index-history_005fquoting_005fstate"><span class="category-def">Variable: </span><span><code class="def-type">int</code> <strong class="def-name">history_quoting_state</strong><a class="copiable-link" href="#index-history_005fquoting_005fstate"> &para;</a></span></dt>
<dd><p>An application may set this variable to indicate that the current line
being expanded is subject to existing quoting.
If set to &lsquo;<samp class="samp">'</samp>&rsquo;,
history expansion assumes that the line is single-quoted and
inhibit expansion until it reads an unquoted closing single quote;
if set to &lsquo;<samp class="samp">&quot;</samp>&rsquo;,
history expansion assumes the line is double quoted
until it reads an unquoted closing double quote.
If set to 0, the default,
history expansion assumes the line is not quoted and
treats quote characters within the line as described above.
This is only effective if <var class="var">history_quotes_inhibit_expansion</var> is set.
This is intended for use by applications like Bash which allow
quoted strings to span multiple lines.
</p></dd></dl>

<dl class="first-deftypevr first-deftypevar-alias-first-deftypevr">
<dt class="deftypevr deftypevar-alias-deftypevr" id="index-history_005finhibit_005fexpansion_005ffunction"><span class="category-def">Variable: </span><span><code class="def-type">rl_linebuf_func_t *</code> <strong class="def-name">history_inhibit_expansion_function</strong><a class="copiable-link" href="#index-history_005finhibit_005fexpansion_005ffunction"> &para;</a></span></dt>
<dd><p>This should be set to the address of a function that takes two arguments:
a <code class="code">char *</code> (<var class="var">string</var>)
and an <code class="code">int</code> index into that string (<var class="var">i</var>).
It should return a non-zero value if the history expansion starting at
<var class="var">string[i]</var> should not be performed; zero if the expansion should
be done.
It is intended for use by applications like Bash that use the history
expansion character for additional purposes.
By default, this variable is set to <code class="code">NULL</code>.
</p></dd></dl>

<hr>
</div>
<div class="section-level-extent" id="History-Programming-Example">
<div class="nav-panel">
<p>
Previous: <a href="#History-Variables" accesskey="p" rel="prev">History Variables</a>, Up: <a href="#Programming-with-GNU-History" accesskey="u" rel="up">Programming with GNU History</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Concept-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h3 class="section" id="History-Programming-Example-1"><span>2.5 History Programming Example<a class="copiable-link" href="#History-Programming-Example-1"> &para;</a></span></h3>

<p>The following program demonstrates simple use of the <small class="sc">GNU</small> History Library.
</p>
<div class="example smallexample">
<pre class="example-preformatted">#include &lt;stdio.h&gt;
#include &lt;readline/history.h&gt;

int
main (int argc, char **argv)
{
  char line[1024], *t;
  int len, done = 0;

  line[0] = 0;

  using_history ();
  while (!done)
    {
      printf (&quot;history$ &quot;);
      fflush (stdout);
      t = fgets (line, sizeof (line) - 1, stdin);
      if (t &amp;&amp; *t)
        {
          len = strlen (t);
          if (t[len - 1] == '\n')
            t[len - 1] = '\0';
        }

      if (!t)
        strcpy (line, &quot;quit&quot;);

      if (line[0])
        {
          char *expansion;
          int result;

          result = history_expand (line, &amp;expansion);
          if (result)
            fprintf (stderr, &quot;%s\n&quot;, expansion);

          if (result &lt; 0 || result == 2)
            {
              free (expansion);
              continue;
            }

          add_history (expansion);
          strncpy (line, expansion, sizeof (line) - 1);
          free (expansion);
        }

      if (strcmp (line, &quot;quit&quot;) == 0)
        done = 1;
      else if (strcmp (line, &quot;save&quot;) == 0)
        write_history (&quot;history_file&quot;);
      else if (strcmp (line, &quot;read&quot;) == 0)
        read_history (&quot;history_file&quot;);
      else if (strcmp (line, &quot;list&quot;) == 0)
        {
          register HIST_ENTRY **the_list;
          register int i;

          the_list = history_list ();
          if (the_list)
            for (i = 0; the_list[i]; i++)
              printf (&quot;%d: %s\n&quot;, i + history_base, the_list[i]-&gt;line);
        }
      else if (strncmp (line, &quot;delete&quot;, 6) == 0)
        {
          int which;
          if ((sscanf (line + 6, &quot;%d&quot;, &amp;which)) == 1)
            {
              HIST_ENTRY *entry = remove_history (which);
              if (!entry)
                fprintf (stderr, &quot;No such entry %d\n&quot;, which);
              else
                {
                  free (entry-&gt;line);
                  free (entry);
                }
            }
          else
            {
              fprintf (stderr, &quot;non-numeric arg given to `delete'\n&quot;);
            }
        }
    }
}
</pre></div>

<hr>
</div>
</div>
<div class="appendix-level-extent" id="GNU-Free-Documentation-License">
<div class="nav-panel">
<p>
Next: <a href="#Concept-Index" accesskey="n" rel="next">Concept Index</a>, Previous: <a href="#Programming-with-GNU-History" accesskey="p" rel="prev">Programming with GNU History</a>, Up: <a href="#Top" accesskey="u" rel="up">GNU History Library</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Concept-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h2 class="appendix" id="GNU-Free-Documentation-License-1"><span>Appendix A GNU Free Documentation License<a class="copiable-link" href="#GNU-Free-Documentation-License-1"> &para;</a></span></h2>

<div class="center">Version 1.3, 3 November 2008
</div>

<div class="display">
<pre class="display-preformatted">Copyright &copy; 2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc.
<a class="uref" href="http://fsf.org/">http://fsf.org/</a>

Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.
</pre></div>

<ol class="enumerate" start="0">
<li> PREAMBLE

<p>The purpose of this License is to make a manual, textbook, or other
functional and useful document <em class="dfn">free</em> in the sense of freedom: to
assure everyone the effective freedom to copy and redistribute it,
with or without modifying it, either commercially or noncommercially.
Secondarily, this License preserves for the author and publisher a way
to get credit for their work, while not being considered responsible
for modifications made by others.
</p>
<p>This License is a kind of &ldquo;copyleft&rdquo;, which means that derivative
works of the document must themselves be free in the same sense.  It
complements the GNU General Public License, which is a copyleft
license designed for free software.
</p>
<p>We have designed this License in order to use it for manuals for free
software, because free software needs free documentation: a free
program should come with manuals providing the same freedoms that the
software does.  But this License is not limited to software manuals;
it can be used for any textual work, regardless of subject matter or
whether it is published as a printed book.  We recommend this License
principally for works whose purpose is instruction or reference.
</p>
</li><li> APPLICABILITY AND DEFINITIONS

<p>This License applies to any manual or other work, in any medium, that
contains a notice placed by the copyright holder saying it can be
distributed under the terms of this License.  Such a notice grants a
world-wide, royalty-free license, unlimited in duration, to use that
work under the conditions stated herein.  The &ldquo;Document&rdquo;, below,
refers to any such manual or work.  Any member of the public is a
licensee, and is addressed as &ldquo;you&rdquo;.  You accept the license if you
copy, modify or distribute the work in a way requiring permission
under copyright law.
</p>
<p>A &ldquo;Modified Version&rdquo; of the Document means any work containing the
Document or a portion of it, either copied verbatim, or with
modifications and/or translated into another language.
</p>
<p>A &ldquo;Secondary Section&rdquo; is a named appendix or a front-matter section
of the Document that deals exclusively with the relationship of the
publishers or authors of the Document to the Document&rsquo;s overall
subject (or to related matters) and contains nothing that could fall
directly within that overall subject.  (Thus, if the Document is in
part a textbook of mathematics, a Secondary Section may not explain
any mathematics.)  The relationship could be a matter of historical
connection with the subject or with related matters, or of legal,
commercial, philosophical, ethical or political position regarding
them.
</p>
<p>The &ldquo;Invariant Sections&rdquo; are certain Secondary Sections whose titles
are designated, as being those of Invariant Sections, in the notice
that says that the Document is released under this License.  If a
section does not fit the above definition of Secondary then it is not
allowed to be designated as Invariant.  The Document may contain zero
Invariant Sections.  If the Document does not identify any Invariant
Sections then there are none.
</p>
<p>The &ldquo;Cover Texts&rdquo; are certain short passages of text that are listed,
as Front-Cover Texts or Back-Cover Texts, in the notice that says that
the Document is released under this License.  A Front-Cover Text may
be at most 5 words, and a Back-Cover Text may be at most 25 words.
</p>
<p>A &ldquo;Transparent&rdquo; copy of the Document means a machine-readable copy,
represented in a format whose specification is available to the
general public, that is suitable for revising the document
straightforwardly with generic text editors or (for images composed of
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drawing editor, and that is suitable for input to text formatters or
for automatic translation to a variety of formats suitable for input
to text formatters.  A copy made in an otherwise Transparent file
format whose markup, or absence of markup, has been arranged to thwart
or discourage subsequent modification by readers is not Transparent.
An image format is not Transparent if used for any substantial amount
of text.  A copy that is not &ldquo;Transparent&rdquo; is called &ldquo;Opaque&rdquo;.
</p>
<p>Examples of suitable formats for Transparent copies include plain
<small class="sc">ASCII</small> without markup, Texinfo input format, LaTeX input
format, <abbr class="acronym">SGML</abbr> or <abbr class="acronym">XML</abbr> using a publicly available
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PostScript or <abbr class="acronym">PDF</abbr> designed for human modification.  Examples
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<abbr class="acronym">JPG</abbr>.  Opaque formats include proprietary formats that can be
read and edited only by proprietary word processors, <abbr class="acronym">SGML</abbr> or
<abbr class="acronym">XML</abbr> for which the <abbr class="acronym">DTD</abbr> and/or processing tools are
not generally available, and the machine-generated <abbr class="acronym">HTML</abbr>,
PostScript or <abbr class="acronym">PDF</abbr> produced by some word processors for
output purposes only.
</p>
<p>The &ldquo;Title Page&rdquo; means, for a printed book, the title page itself,
plus such following pages as are needed to hold, legibly, the material
this License requires to appear in the title page.  For works in
formats which do not have any title page as such, &ldquo;Title Page&rdquo; means
the text near the most prominent appearance of the work&rsquo;s title,
preceding the beginning of the body of the text.
</p>
<p>The &ldquo;publisher&rdquo; means any person or entity that distributes copies
of the Document to the public.
</p>
<p>A section &ldquo;Entitled XYZ&rdquo; means a named subunit of the Document whose
title either is precisely XYZ or contains XYZ in parentheses following
text that translates XYZ in another language.  (Here XYZ stands for a
specific section name mentioned below, such as &ldquo;Acknowledgements&rdquo;,
&ldquo;Dedications&rdquo;, &ldquo;Endorsements&rdquo;, or &ldquo;History&rdquo;.)  To &ldquo;Preserve the Title&rdquo;
of such a section when you modify the Document means that it remains a
section &ldquo;Entitled XYZ&rdquo; according to this definition.
</p>
<p>The Document may include Warranty Disclaimers next to the notice which
states that this License applies to the Document.  These Warranty
Disclaimers are considered to be included by reference in this
License, but only as regards disclaiming warranties: any other
implication that these Warranty Disclaimers may have is void and has
no effect on the meaning of this License.
</p>
</li><li> VERBATIM COPYING

<p>You may copy and distribute the Document in any medium, either
commercially or noncommercially, provided that this License, the
copyright notices, and the license notice saying this License applies
to the Document are reproduced in all copies, and that you add no other
conditions whatsoever to those of this License.  You may not use
technical measures to obstruct or control the reading or further
copying of the copies you make or distribute.  However, you may accept
compensation in exchange for copies.  If you distribute a large enough
number of copies you must also follow the conditions in section 3.
</p>
<p>You may also lend copies, under the same conditions stated above, and
you may publicly display copies.
</p>
</li><li> COPYING IN QUANTITY

<p>If you publish printed copies (or copies in media that commonly have
printed covers) of the Document, numbering more than 100, and the
Document&rsquo;s license notice requires Cover Texts, you must enclose the
copies in covers that carry, clearly and legibly, all these Cover
Texts: Front-Cover Texts on the front cover, and Back-Cover Texts on
the back cover.  Both covers must also clearly and legibly identify
you as the publisher of these copies.  The front cover must present
the full title with all words of the title equally prominent and
visible.  You may add other material on the covers in addition.
Copying with changes limited to the covers, as long as they preserve
the title of the Document and satisfy these conditions, can be treated
as verbatim copying in other respects.
</p>
<p>If the required texts for either cover are too voluminous to fit
legibly, you should put the first ones listed (as many as fit
reasonably) on the actual cover, and continue the rest onto adjacent
pages.
</p>
<p>If you publish or distribute Opaque copies of the Document numbering
more than 100, you must either include a machine-readable Transparent
copy along with each Opaque copy, or state in or with each Opaque copy
a computer-network location from which the general network-using
public has access to download using public-standard network protocols
a complete Transparent copy of the Document, free of added material.
If you use the latter option, you must take reasonably prudent steps,
when you begin distribution of Opaque copies in quantity, to ensure
that this Transparent copy will remain thus accessible at the stated
location until at least one year after the last time you distribute an
Opaque copy (directly or through your agents or retailers) of that
edition to the public.
</p>
<p>It is requested, but not required, that you contact the authors of the
Document well before redistributing any large number of copies, to give
them a chance to provide you with an updated version of the Document.
</p>
</li><li> MODIFICATIONS

<p>You may copy and distribute a Modified Version of the Document under
the conditions of sections 2 and 3 above, provided that you release
the Modified Version under precisely this License, with the Modified
Version filling the role of the Document, thus licensing distribution
and modification of the Modified Version to whoever possesses a copy
of it.  In addition, you must do these things in the Modified Version:
</p>
<ol class="enumerate" type="A" start="1">
<li> Use in the Title Page (and on the covers, if any) a title distinct
from that of the Document, and from those of previous versions
(which should, if there were any, be listed in the History section
of the Document).  You may use the same title as a previous version
if the original publisher of that version gives permission.

</li><li> List on the Title Page, as authors, one or more persons or entities
responsible for authorship of the modifications in the Modified
Version, together with at least five of the principal authors of the
Document (all of its principal authors, if it has fewer than five),
unless they release you from this requirement.

</li><li> State on the Title page the name of the publisher of the
Modified Version, as the publisher.

</li><li> Preserve all the copyright notices of the Document.

</li><li> Add an appropriate copyright notice for your modifications
adjacent to the other copyright notices.

</li><li> Include, immediately after the copyright notices, a license notice
giving the public permission to use the Modified Version under the
terms of this License, in the form shown in the Addendum below.

</li><li> Preserve in that license notice the full lists of Invariant Sections
and required Cover Texts given in the Document&rsquo;s license notice.

</li><li> Include an unaltered copy of this License.

</li><li> Preserve the section Entitled &ldquo;History&rdquo;, Preserve its Title, and add
to it an item stating at least the title, year, new authors, and
publisher of the Modified Version as given on the Title Page.  If
there is no section Entitled &ldquo;History&rdquo; in the Document, create one
stating the title, year, authors, and publisher of the Document as
given on its Title Page, then add an item describing the Modified
Version as stated in the previous sentence.

</li><li> Preserve the network location, if any, given in the Document for
public access to a Transparent copy of the Document, and likewise
the network locations given in the Document for previous versions
it was based on.  These may be placed in the &ldquo;History&rdquo; section.
You may omit a network location for a work that was published at
least four years before the Document itself, or if the original
publisher of the version it refers to gives permission.

</li><li> For any section Entitled &ldquo;Acknowledgements&rdquo; or &ldquo;Dedications&rdquo;, Preserve
the Title of the section, and preserve in the section all the
substance and tone of each of the contributor acknowledgements and/or
dedications given therein.

</li><li> Preserve all the Invariant Sections of the Document,
unaltered in their text and in their titles.  Section numbers
or the equivalent are not considered part of the section titles.

</li><li> Delete any section Entitled &ldquo;Endorsements&rdquo;.  Such a section
may not be included in the Modified Version.

</li><li> Do not retitle any existing section to be Entitled &ldquo;Endorsements&rdquo; or
to conflict in title with any Invariant Section.

</li><li> Preserve any Warranty Disclaimers.
</li></ol>

<p>If the Modified Version includes new front-matter sections or
appendices that qualify as Secondary Sections and contain no material
copied from the Document, you may at your option designate some or all
of these sections as invariant.  To do this, add their titles to the
list of Invariant Sections in the Modified Version&rsquo;s license notice.
These titles must be distinct from any other section titles.
</p>
<p>You may add a section Entitled &ldquo;Endorsements&rdquo;, provided it contains
nothing but endorsements of your Modified Version by various
parties&mdash;for example, statements of peer review or that the text has
been approved by an organization as the authoritative definition of a
standard.
</p>
<p>You may add a passage of up to five words as a Front-Cover Text, and a
passage of up to 25 words as a Back-Cover Text, to the end of the list
of Cover Texts in the Modified Version.  Only one passage of
Front-Cover Text and one of Back-Cover Text may be added by (or
through arrangements made by) any one entity.  If the Document already
includes a cover text for the same cover, previously added by you or
by arrangement made by the same entity you are acting on behalf of,
you may not add another; but you may replace the old one, on explicit
permission from the previous publisher that added the old one.
</p>
<p>The author(s) and publisher(s) of the Document do not by this License
give permission to use their names for publicity for or to assert or
imply endorsement of any Modified Version.
</p>
</li><li> COMBINING DOCUMENTS

<p>You may combine the Document with other documents released under this
License, under the terms defined in section 4 above for modified
versions, provided that you include in the combination all of the
Invariant Sections of all of the original documents, unmodified, and
list them all as Invariant Sections of your combined work in its
license notice, and that you preserve all their Warranty Disclaimers.
</p>
<p>The combined work need only contain one copy of this License, and
multiple identical Invariant Sections may be replaced with a single
copy.  If there are multiple Invariant Sections with the same name but
different contents, make the title of each such section unique by
adding at the end of it, in parentheses, the name of the original
author or publisher of that section if known, or else a unique number.
Make the same adjustment to the section titles in the list of
Invariant Sections in the license notice of the combined work.
</p>
<p>In the combination, you must combine any sections Entitled &ldquo;History&rdquo;
in the various original documents, forming one section Entitled
&ldquo;History&rdquo;; likewise combine any sections Entitled &ldquo;Acknowledgements&rdquo;,
and any sections Entitled &ldquo;Dedications&rdquo;.  You must delete all
sections Entitled &ldquo;Endorsements.&rdquo;
</p>
</li><li> COLLECTIONS OF DOCUMENTS

<p>You may make a collection consisting of the Document and other documents
released under this License, and replace the individual copies of this
License in the various documents with a single copy that is included in
the collection, provided that you follow the rules of this License for
verbatim copying of each of the documents in all other respects.
</p>
<p>You may extract a single document from such a collection, and distribute
it individually under this License, provided you insert a copy of this
License into the extracted document, and follow this License in all
other respects regarding verbatim copying of that document.
</p>
</li><li> AGGREGATION WITH INDEPENDENT WORKS

<p>A compilation of the Document or its derivatives with other separate
and independent documents or works, in or on a volume of a storage or
distribution medium, is called an &ldquo;aggregate&rdquo; if the copyright
resulting from the compilation is not used to limit the legal rights
of the compilation&rsquo;s users beyond what the individual works permit.
When the Document is included in an aggregate, this License does not
apply to the other works in the aggregate which are not themselves
derivative works of the Document.
</p>
<p>If the Cover Text requirement of section 3 is applicable to these
copies of the Document, then if the Document is less than one half of
the entire aggregate, the Document&rsquo;s Cover Texts may be placed on
covers that bracket the Document within the aggregate, or the
electronic equivalent of covers if the Document is in electronic form.
Otherwise they must appear on printed covers that bracket the whole
aggregate.
</p>
</li><li> TRANSLATION

<p>Translation is considered a kind of modification, so you may
distribute translations of the Document under the terms of section 4.
Replacing Invariant Sections with translations requires special
permission from their copyright holders, but you may include
translations of some or all Invariant Sections in addition to the
original versions of these Invariant Sections.  You may include a
translation of this License, and all the license notices in the
Document, and any Warranty Disclaimers, provided that you also include
the original English version of this License and the original versions
of those notices and disclaimers.  In case of a disagreement between
the translation and the original version of this License or a notice
or disclaimer, the original version will prevail.
</p>
<p>If a section in the Document is Entitled &ldquo;Acknowledgements&rdquo;,
&ldquo;Dedications&rdquo;, or &ldquo;History&rdquo;, the requirement (section 4) to Preserve
its Title (section 1) will typically require changing the actual
title.
</p>
</li><li> TERMINATION

<p>You may not copy, modify, sublicense, or distribute the Document
except as expressly provided under this License.  Any attempt
otherwise to copy, modify, sublicense, or distribute it is void, and
will automatically terminate your rights under this License.
</p>
<p>However, if you cease all violation of this License, then your license
from a particular copyright holder is reinstated (a) provisionally,
unless and until the copyright holder explicitly and finally
terminates your license, and (b) permanently, if the copyright holder
fails to notify you of the violation by some reasonable means prior to
60 days after the cessation.
</p>
<p>Moreover, your license from a particular copyright holder is
reinstated permanently if the copyright holder notifies you of the
violation by some reasonable means, this is the first time you have
received notice of violation of this License (for any work) from that
copyright holder, and you cure the violation prior to 30 days after
your receipt of the notice.
</p>
<p>Termination of your rights under this section does not terminate the
licenses of parties who have received copies or rights from you under
this License.  If your rights have been terminated and not permanently
reinstated, receipt of a copy of some or all of the same material does
not give you any rights to use it.
</p>
</li><li> FUTURE REVISIONS OF THIS LICENSE

<p>The Free Software Foundation may publish new, revised versions
of the GNU Free Documentation License from time to time.  Such new
versions will be similar in spirit to the present version, but may
differ in detail to address new problems or concerns.  See
<a class="uref" href="http://www.gnu.org/copyleft/">http://www.gnu.org/copyleft/</a>.
</p>
<p>Each version of the License is given a distinguishing version number.
If the Document specifies that a particular numbered version of this
License &ldquo;or any later version&rdquo; applies to it, you have the option of
following the terms and conditions either of that specified version or
of any later version that has been published (not as a draft) by the
Free Software Foundation.  If the Document does not specify a version
number of this License, you may choose any version ever published (not
as a draft) by the Free Software Foundation.  If the Document
specifies that a proxy can decide which future versions of this
License can be used, that proxy&rsquo;s public statement of acceptance of a
version permanently authorizes you to choose that version for the
Document.
</p>
</li><li> RELICENSING

<p>&ldquo;Massive Multiauthor Collaboration Site&rdquo; (or &ldquo;MMC Site&rdquo;) means any
World Wide Web server that publishes copyrightable works and also
provides prominent facilities for anybody to edit those works.  A
public wiki that anybody can edit is an example of such a server.  A
&ldquo;Massive Multiauthor Collaboration&rdquo; (or &ldquo;MMC&rdquo;) contained in the
site means any set of copyrightable works thus published on the MMC
site.
</p>
<p>&ldquo;CC-BY-SA&rdquo; means the Creative Commons Attribution-Share Alike 3.0
license published by Creative Commons Corporation, a not-for-profit
corporation with a principal place of business in San Francisco,
California, as well as future copyleft versions of that license
published by that same organization.
</p>
<p>&ldquo;Incorporate&rdquo; means to publish or republish a Document, in whole or
in part, as part of another Document.
</p>
<p>An MMC is &ldquo;eligible for relicensing&rdquo; if it is licensed under this
License, and if all works that were first published under this License
somewhere other than this MMC, and subsequently incorporated in whole
or in part into the MMC, (1) had no cover texts or invariant sections,
and (2) were thus incorporated prior to November 1, 2008.
</p>
<p>The operator of an MMC Site may republish an MMC contained in the site
under CC-BY-SA on the same site at any time before August 1, 2009,
provided the MMC is eligible for relicensing.
</p>
</li></ol>

<h3 class="heading" id="ADDENDUM_003a-How-to-use-this-License-for-your-documents"><span>ADDENDUM: How to use this License for your documents<a class="copiable-link" href="#ADDENDUM_003a-How-to-use-this-License-for-your-documents"> &para;</a></span></h3>

<p>To use this License in a document you have written, include a copy of
the License in the document and put the following copyright and
license notices just after the title page:
</p>
<div class="example smallexample">
<div class="group"><pre class="example-preformatted">  Copyright (C)  <var class="var">year</var>  <var class="var">your name</var>.
  Permission is granted to copy, distribute and/or modify this document
  under the terms of the GNU Free Documentation License, Version 1.3
  or any later version published by the Free Software Foundation;
  with no Invariant Sections, no Front-Cover Texts, and no Back-Cover
  Texts.  A copy of the license is included in the section entitled ``GNU
  Free Documentation License''.
</pre></div></div>

<p>If you have Invariant Sections, Front-Cover Texts and Back-Cover Texts,
replace the &ldquo;with&hellip;Texts.&rdquo; line with this:
</p>
<div class="example smallexample">
<div class="group"><pre class="example-preformatted">    with the Invariant Sections being <var class="var">list their titles</var>, with
    the Front-Cover Texts being <var class="var">list</var>, and with the Back-Cover Texts
    being <var class="var">list</var>.
</pre></div></div>

<p>If you have Invariant Sections without Cover Texts, or some other
combination of the three, merge those two alternatives to suit the
situation.
</p>
<p>If your document contains nontrivial examples of program code, we
recommend releasing these examples in parallel under your choice of
free software license, such as the GNU General Public License,
to permit their use in free software.
</p>


<hr>
</div>
<div class="appendix-level-extent" id="Concept-Index">
<div class="nav-panel">
<p>
Next: <a href="#Function-and-Variable-Index" accesskey="n" rel="next">Function and Variable Index</a>, Previous: <a href="#GNU-Free-Documentation-License" accesskey="p" rel="prev">GNU Free Documentation License</a>, Up: <a href="#Top" accesskey="u" rel="up">GNU History Library</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Concept-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h2 class="appendix" id="Concept-Index-1"><span>Appendix B Concept Index<a class="copiable-link" href="#Concept-Index-1"> &para;</a></span></h2>
<div class="printindex cp-printindex">
<table class="cp-letters-header-printindex"><tr><th>Jump to: &nbsp; </th><td><a class="summary-letter-printindex" href="#Concept-Index_cp_letter-A"><b>A</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-E"><b>E</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-H"><b>H</b></a>
 &nbsp; 
</td></tr></table>
<table class="cp-entries-printindex" border="0">
<tr><td></td><th class="entries-header-printindex">Index Entry</th><th class="sections-header-printindex">Section</th></tr>
<tr><td colspan="3"><hr></td></tr>
<tr><th id="Concept-Index_cp_letter-A">A</th></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-anchored-search">anchored search</a></td><td class="printindex-index-section"><a href="#Searching-the-History-List">Searching the History List</a></td></tr>
<tr><td colspan="3"><hr></td></tr>
<tr><th id="Concept-Index_cp_letter-E">E</th></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-event-designators">event designators</a></td><td class="printindex-index-section"><a href="#Event-Designators">Event Designators</a></td></tr>
<tr><td colspan="3"><hr></td></tr>
<tr><th id="Concept-Index_cp_letter-H">H</th></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-history-events">history events</a></td><td class="printindex-index-section"><a href="#Event-Designators">Event Designators</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-history-expansion">history expansion</a></td><td class="printindex-index-section"><a href="#History-Interaction">History Interaction</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-History-Searching">History Searching</a></td><td class="printindex-index-section"><a href="#Searching-the-History-List">Searching the History List</a></td></tr>
<tr><td colspan="3"><hr></td></tr>
</table>
<table class="cp-letters-footer-printindex"><tr><th>Jump to: &nbsp; </th><td><a class="summary-letter-printindex" href="#Concept-Index_cp_letter-A"><b>A</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-E"><b>E</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Concept-Index_cp_letter-H"><b>H</b></a>
 &nbsp; 
</td></tr></table>
</div>

<hr>
</div>
<div class="appendix-level-extent" id="Function-and-Variable-Index">
<div class="nav-panel">
<p>
Previous: <a href="#Concept-Index" accesskey="p" rel="prev">Concept Index</a>, Up: <a href="#Top" accesskey="u" rel="up">GNU History Library</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Concept-Index" title="Index" rel="index">Index</a>]</p>
</div>
<h2 class="appendix" id="Function-and-Variable-Index-1"><span>Appendix C Function and Variable Index<a class="copiable-link" href="#Function-and-Variable-Index-1"> &para;</a></span></h2>
<div class="printindex vr-printindex">
<table class="vr-letters-header-printindex"><tr><th>Jump to: &nbsp; </th><td><a class="summary-letter-printindex" href="#Function-and-Variable-Index_vr_letter-A"><b>A</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Function-and-Variable-Index_vr_letter-C"><b>C</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Function-and-Variable-Index_vr_letter-F"><b>F</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Function-and-Variable-Index_vr_letter-G"><b>G</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Function-and-Variable-Index_vr_letter-H"><b>H</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Function-and-Variable-Index_vr_letter-N"><b>N</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Function-and-Variable-Index_vr_letter-P"><b>P</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Function-and-Variable-Index_vr_letter-R"><b>R</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Function-and-Variable-Index_vr_letter-S"><b>S</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Function-and-Variable-Index_vr_letter-U"><b>U</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Function-and-Variable-Index_vr_letter-W"><b>W</b></a>
 &nbsp; 
</td></tr></table>
<table class="vr-entries-printindex" border="0">
<tr><td></td><th class="entries-header-printindex">Index Entry</th><th class="sections-header-printindex">Section</th></tr>
<tr><td colspan="3"><hr></td></tr>
<tr><th id="Function-and-Variable-Index_vr_letter-A">A</th></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-add_005fhistory"><code>add_history</code></a></td><td class="printindex-index-section"><a href="#History-List-Management">History List Management</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-add_005fhistory_005ftime"><code>add_history_time</code></a></td><td class="printindex-index-section"><a href="#History-List-Management">History List Management</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-append_005fhistory"><code>append_history</code></a></td><td class="printindex-index-section"><a href="#Managing-the-History-File">Managing the History File</a></td></tr>
<tr><td colspan="3"><hr></td></tr>
<tr><th id="Function-and-Variable-Index_vr_letter-C">C</th></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-clear_005fhistory"><code>clear_history</code></a></td><td class="printindex-index-section"><a href="#History-List-Management">History List Management</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-current_005fhistory"><code>current_history</code></a></td><td class="printindex-index-section"><a href="#Information-About-the-History-List">Information About the History List</a></td></tr>
<tr><td colspan="3"><hr></td></tr>
<tr><th id="Function-and-Variable-Index_vr_letter-F">F</th></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-free_005fhistory_005fentry"><code>free_history_entry</code></a></td><td class="printindex-index-section"><a href="#History-List-Management">History List Management</a></td></tr>
<tr><td colspan="3"><hr></td></tr>
<tr><th id="Function-and-Variable-Index_vr_letter-G">G</th></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-get_005fhistory_005fevent"><code>get_history_event</code></a></td><td class="printindex-index-section"><a href="#History-Expansion">History Expansion</a></td></tr>
<tr><td colspan="3"><hr></td></tr>
<tr><th id="Function-and-Variable-Index_vr_letter-H">H</th></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-history_005farg_005fextract"><code>history_arg_extract</code></a></td><td class="printindex-index-section"><a href="#History-Expansion">History Expansion</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-history_005fbase"><code>history_base</code></a></td><td class="printindex-index-section"><a href="#History-Variables">History Variables</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-history_005fcomment_005fchar"><code>history_comment_char</code></a></td><td class="printindex-index-section"><a href="#History-Variables">History Variables</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-history_005fexpand"><code>history_expand</code></a></td><td class="printindex-index-section"><a href="#History-Expansion">History Expansion</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-history_005fexpansion_005fchar"><code>history_expansion_char</code></a></td><td class="printindex-index-section"><a href="#History-Variables">History Variables</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-history_005fget"><code>history_get</code></a></td><td class="printindex-index-section"><a href="#Information-About-the-History-List">Information About the History List</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-history_005fget_005fhistory_005fstate"><code>history_get_history_state</code></a></td><td class="printindex-index-section"><a href="#Initializing-History-and-State-Management">Initializing History and State Management</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-history_005fget_005ftime"><code>history_get_time</code></a></td><td class="printindex-index-section"><a href="#Information-About-the-History-List">Information About the History List</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-history_005finhibit_005fexpansion_005ffunction"><code>history_inhibit_expansion_function</code></a></td><td class="printindex-index-section"><a href="#History-Variables">History Variables</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-history_005fis_005fstifled"><code>history_is_stifled</code></a></td><td class="printindex-index-section"><a href="#History-List-Management">History List Management</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-history_005flength"><code>history_length</code></a></td><td class="printindex-index-section"><a href="#History-Variables">History Variables</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-history_005flist"><code>history_list</code></a></td><td class="printindex-index-section"><a href="#Information-About-the-History-List">Information About the History List</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-history_005fmax_005fentries"><code>history_max_entries</code></a></td><td class="printindex-index-section"><a href="#History-Variables">History Variables</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-history_005fno_005fexpand_005fchars"><code>history_no_expand_chars</code></a></td><td class="printindex-index-section"><a href="#History-Variables">History Variables</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-history_005fquotes_005finhibit_005fexpansion"><code>history_quotes_inhibit_expansion</code></a></td><td class="printindex-index-section"><a href="#History-Variables">History Variables</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-history_005fquoting_005fstate"><code>history_quoting_state</code></a></td><td class="printindex-index-section"><a href="#History-Variables">History Variables</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-history_005fsearch"><code>history_search</code></a></td><td class="printindex-index-section"><a href="#Searching-the-History-List">Searching the History List</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-history_005fsearch_005fdelimiter_005fchars"><code>history_search_delimiter_chars</code></a></td><td class="printindex-index-section"><a href="#History-Variables">History Variables</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-history_005fsearch_005fpos"><code>history_search_pos</code></a></td><td class="printindex-index-section"><a href="#Searching-the-History-List">Searching the History List</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-history_005fsearch_005fprefix"><code>history_search_prefix</code></a></td><td class="printindex-index-section"><a href="#Searching-the-History-List">Searching the History List</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-history_005fset_005fhistory_005fstate"><code>history_set_history_state</code></a></td><td class="printindex-index-section"><a href="#Initializing-History-and-State-Management">Initializing History and State Management</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-history_005fset_005fpos"><code>history_set_pos</code></a></td><td class="printindex-index-section"><a href="#Moving-Around-the-History-List">Moving Around the History List</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-history_005fsubst_005fchar"><code>history_subst_char</code></a></td><td class="printindex-index-section"><a href="#History-Variables">History Variables</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-history_005ftokenize"><code>history_tokenize</code></a></td><td class="printindex-index-section"><a href="#History-Expansion">History Expansion</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-history_005ftotal_005fbytes"><code>history_total_bytes</code></a></td><td class="printindex-index-section"><a href="#Information-About-the-History-List">Information About the History List</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-history_005ftruncate_005ffile"><code>history_truncate_file</code></a></td><td class="printindex-index-section"><a href="#Managing-the-History-File">Managing the History File</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-history_005fword_005fdelimiters"><code>history_word_delimiters</code></a></td><td class="printindex-index-section"><a href="#History-Variables">History Variables</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-history_005fwrite_005ftimestamps"><code>history_write_timestamps</code></a></td><td class="printindex-index-section"><a href="#History-Variables">History Variables</a></td></tr>
<tr><td colspan="3"><hr></td></tr>
<tr><th id="Function-and-Variable-Index_vr_letter-N">N</th></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-next_005fhistory"><code>next_history</code></a></td><td class="printindex-index-section"><a href="#Moving-Around-the-History-List">Moving Around the History List</a></td></tr>
<tr><td colspan="3"><hr></td></tr>
<tr><th id="Function-and-Variable-Index_vr_letter-P">P</th></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-previous_005fhistory"><code>previous_history</code></a></td><td class="printindex-index-section"><a href="#Moving-Around-the-History-List">Moving Around the History List</a></td></tr>
<tr><td colspan="3"><hr></td></tr>
<tr><th id="Function-and-Variable-Index_vr_letter-R">R</th></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-read_005fhistory"><code>read_history</code></a></td><td class="printindex-index-section"><a href="#Managing-the-History-File">Managing the History File</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-read_005fhistory_005frange"><code>read_history_range</code></a></td><td class="printindex-index-section"><a href="#Managing-the-History-File">Managing the History File</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-remove_005fhistory"><code>remove_history</code></a></td><td class="printindex-index-section"><a href="#History-List-Management">History List Management</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-replace_005fhistory_005fentry"><code>replace_history_entry</code></a></td><td class="printindex-index-section"><a href="#History-List-Management">History List Management</a></td></tr>
<tr><td colspan="3"><hr></td></tr>
<tr><th id="Function-and-Variable-Index_vr_letter-S">S</th></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-stifle_005fhistory"><code>stifle_history</code></a></td><td class="printindex-index-section"><a href="#History-List-Management">History List Management</a></td></tr>
<tr><td colspan="3"><hr></td></tr>
<tr><th id="Function-and-Variable-Index_vr_letter-U">U</th></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-unstifle_005fhistory"><code>unstifle_history</code></a></td><td class="printindex-index-section"><a href="#History-List-Management">History List Management</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-using_005fhistory"><code>using_history</code></a></td><td class="printindex-index-section"><a href="#Initializing-History-and-State-Management">Initializing History and State Management</a></td></tr>
<tr><td colspan="3"><hr></td></tr>
<tr><th id="Function-and-Variable-Index_vr_letter-W">W</th></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-where_005fhistory"><code>where_history</code></a></td><td class="printindex-index-section"><a href="#Information-About-the-History-List">Information About the History List</a></td></tr>
<tr><td></td><td class="printindex-index-entry"><a href="#index-write_005fhistory"><code>write_history</code></a></td><td class="printindex-index-section"><a href="#Managing-the-History-File">Managing the History File</a></td></tr>
<tr><td colspan="3"><hr></td></tr>
</table>
<table class="vr-letters-footer-printindex"><tr><th>Jump to: &nbsp; </th><td><a class="summary-letter-printindex" href="#Function-and-Variable-Index_vr_letter-A"><b>A</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Function-and-Variable-Index_vr_letter-C"><b>C</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Function-and-Variable-Index_vr_letter-F"><b>F</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Function-and-Variable-Index_vr_letter-G"><b>G</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Function-and-Variable-Index_vr_letter-H"><b>H</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Function-and-Variable-Index_vr_letter-N"><b>N</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Function-and-Variable-Index_vr_letter-P"><b>P</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Function-and-Variable-Index_vr_letter-R"><b>R</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Function-and-Variable-Index_vr_letter-S"><b>S</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Function-and-Variable-Index_vr_letter-U"><b>U</b></a>
 &nbsp; 
<a class="summary-letter-printindex" href="#Function-and-Variable-Index_vr_letter-W"><b>W</b></a>
 &nbsp; 
</td></tr></table>
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