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<H1>GNU History Library</H1></P><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><P>

<BLOCKQUOTE><TABLE BORDER=0 CELLSPACING=0> 
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="history.html#SEC1">1. Using History Interactively</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">GNU History User's Manual.</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="history.html#SEC6">2. Programming with GNU History</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">GNU History Programmer's Manual.</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="history.html#SEC19">A. Copying This Manual</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP"></TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="history.html#SEC22">B. Concept Index</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Index of concepts described in this manual.</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="history.html#SEC23">C. Function and Variable Index</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Index of externally visible functions
				  and variables.</TD></TR>
</TABLE></BLOCKQUOTE>
<P>

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<A NAME="Using History Interactively"></A>
<H1> 1. Using History Interactively </H1>
<!--docid::SEC1::-->
<P>

This chapter describes how to use the GNU History Library interactively,
from a user's standpoint.  It should be considered a user's guide.  For
information on using the GNU History Library in your own programs,
see section <A HREF="history.html#SEC6">2. Programming with GNU History</A>.
</P><P>

<BLOCKQUOTE><TABLE BORDER=0 CELLSPACING=0> 
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="history.html#SEC2">1.1 History Expansion</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">What it feels like using History as a user.</TD></TR>
</TABLE></BLOCKQUOTE>
<P>

<A NAME="History Interaction"></A>
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<H2> 1.1 History Expansion </H2>
<!--docid::SEC2::-->
<P>

The History library provides a history expansion feature that is similar
to the history expansion provided by <CODE>csh</CODE>.  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 line from the history list should be used during substitution.
The second is to select portions of that line for inclusion into the
current one.  The line selected from the history is called the
<EM>event</EM>, and the portions of that line that are acted upon are
called <EM>words</EM>.  Various <EM>modifiers</EM> are available to manipulate
the selected words.  The line is broken into words in the same fashion
that Bash does, so that several words
surrounded by quotes are considered one word.
History expansions are introduced by the appearance of the
history expansion character, which is <SAMP>`!'</SAMP> by default.
</P><P>

<BLOCKQUOTE><TABLE BORDER=0 CELLSPACING=0> 
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="history.html#SEC3">1.1.1 Event Designators</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">How to specify which history line to use.</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="history.html#SEC4">1.1.2 Word Designators</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Specifying which words are of interest.</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="history.html#SEC5">1.1.3 Modifiers</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Modifying the results of substitution.</TD></TR>
</TABLE></BLOCKQUOTE>
<P>

<A NAME="Event Designators"></A>
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<H3> 1.1.1 Event Designators </H3>
<!--docid::SEC3::-->
<P>

An event designator is a reference to a command line entry in the
history list.
<A NAME="IDX1"></A>
</P><P>

<DL COMPACT>

<DT><CODE>!</CODE>
<DD>Start a history substitution, except when followed by a space, tab,
the end of the line, or <SAMP>`='</SAMP>.
<P>

<DT><CODE>!<VAR>n</VAR></CODE>
<DD>Refer to command line <VAR>n</VAR>.
<P>

<DT><CODE>!-<VAR>n</VAR></CODE>
<DD>Refer to the command <VAR>n</VAR> lines back.
<P>

<DT><CODE>!!</CODE>
<DD>Refer to the previous command.  This is a synonym for <SAMP>`!-1'</SAMP>.
<P>

<DT><CODE>!<VAR>string</VAR></CODE>
<DD>Refer to the most recent command starting with <VAR>string</VAR>.
<P>

<DT><CODE>!?<VAR>string</VAR>[?]</CODE>
<DD>Refer to the most recent command containing <VAR>string</VAR>.  The trailing
<SAMP>`?'</SAMP> may be omitted if the <VAR>string</VAR> is followed immediately by
a newline.
<P>

<DT><CODE>^<VAR>string1</VAR>^<VAR>string2</VAR>^</CODE>
<DD>Quick Substitution.  Repeat the last command, replacing <VAR>string1</VAR>
with <VAR>string2</VAR>.  Equivalent to
<CODE>!!:s/<VAR>string1</VAR>/<VAR>string2</VAR>/</CODE>.
<P>

<DT><CODE>!#</CODE>
<DD>The entire command line typed so far.
<P>

</DL>
<P>

<A NAME="Word Designators"></A>
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<H3> 1.1.2 Word Designators </H3>
<!--docid::SEC4::-->
<P>

Word designators are used to select desired words from the event.
A <SAMP>`:'</SAMP> separates the event specification from the word designator.  It
may be omitted if the word designator begins with a <SAMP>`^'</SAMP>, <SAMP>`$'</SAMP>,
<SAMP>`*'</SAMP>, <SAMP>`-'</SAMP>, or <SAMP>`%'</SAMP>.  Words are numbered from the beginning
of the line, with the first word being denoted by 0 (zero).  Words are
inserted into the current line separated by single spaces.
</P><P>

For example,
</P><P>

<DL COMPACT>
<DT><CODE>!!</CODE>
<DD>designates the preceding command.  When you type this, the preceding
command is repeated in toto.
<P>

<DT><CODE>!!:$</CODE>
<DD>designates the last argument of the preceding command.  This may be
shortened to <CODE>!$</CODE>.
<P>

<DT><CODE>!fi:2</CODE>
<DD>designates the second argument of the most recent command starting with
the letters <CODE>fi</CODE>.
</DL>
<P>

Here are the word designators:
 
<DL COMPACT>

<DT><CODE>0 (zero)</CODE>
<DD>The <CODE>0</CODE>th word.  For many applications, this is the command word.
<P>

<DT><CODE><VAR>n</VAR></CODE>
<DD>The <VAR>n</VAR>th word.
<P>

<DT><CODE>^</CODE>
<DD>The first argument; that is, word 1.
<P>

<DT><CODE>$</CODE>
<DD>The last argument.
<P>

<DT><CODE>%</CODE>
<DD>The word matched by the most recent <SAMP>`?<VAR>string</VAR>?'</SAMP> search.
<P>

<DT><CODE><VAR>x</VAR>-<VAR>y</VAR></CODE>
<DD>A range of words; <SAMP>`-<VAR>y</VAR>'</SAMP> abbreviates <SAMP>`0-<VAR>y</VAR>'</SAMP>.
<P>

<DT><CODE>*</CODE>
<DD>All of the words, except the <CODE>0</CODE>th.  This is a synonym for <SAMP>`1-$'</SAMP>.
It is not an error to use <SAMP>`*'</SAMP> if there is just one word in the event;
the empty string is returned in that case.
<P>

<DT><CODE><VAR>x</VAR>*</CODE>
<DD>Abbreviates <SAMP>`<VAR>x</VAR>-$'</SAMP>
<P>

<DT><CODE><VAR>x</VAR>-</CODE>
<DD>Abbreviates <SAMP>`<VAR>x</VAR>-$'</SAMP> like <SAMP>`<VAR>x</VAR>*'</SAMP>, but omits the last word.
<P>

</DL>
<P>

If a word designator is supplied without an event specification, the
previous command is used as the event.
</P><P>

<A NAME="Modifiers"></A>
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<H3> 1.1.3 Modifiers </H3>
<!--docid::SEC5::-->
<P>

After the optional word designator, you can add a sequence of one or more
of the following modifiers, each preceded by a <SAMP>`:'</SAMP>.
</P><P>

<DL COMPACT>

<DT><CODE>h</CODE>
<DD>Remove a trailing pathname component, leaving only the head.
<P>

<DT><CODE>t</CODE>
<DD>Remove all leading  pathname  components, leaving the tail.
<P>

<DT><CODE>r</CODE>
<DD>Remove a trailing suffix of the form <SAMP>`.<VAR>suffix</VAR>'</SAMP>, leaving
the basename.
<P>

<DT><CODE>e</CODE>
<DD>Remove all but the trailing suffix.
<P>

<DT><CODE>p</CODE>
<DD>Print the new command but do not execute it.
<P>

<DT><CODE>s/<VAR>old</VAR>/<VAR>new</VAR>/</CODE>
<DD>Substitute <VAR>new</VAR> for the first occurrence of <VAR>old</VAR> in the
event line.  Any delimiter may be used in place of <SAMP>`/'</SAMP>.
The delimiter may be quoted in <VAR>old</VAR> and <VAR>new</VAR>
with a single backslash.  If <SAMP>`&#38;'</SAMP> appears in <VAR>new</VAR>,
it is replaced by <VAR>old</VAR>.  A single backslash will quote
the <SAMP>`&#38;'</SAMP>.  The final delimiter is optional if it is the last
character on the input line.
<P>

<DT><CODE>&#38;</CODE>
<DD>Repeat the previous substitution.
<P>

<DT><CODE>g</CODE>
<DD><DT><CODE>a</CODE>
<DD>Cause changes to be applied over the entire event line.  Used in
conjunction with <SAMP>`s'</SAMP>, as in <CODE>gs/<VAR>old</VAR>/<VAR>new</VAR>/</CODE>,
or with <SAMP>`&#38;'</SAMP>.
<P>

<DT><CODE>G</CODE>
<DD>Apply the following <SAMP>`s'</SAMP> modifier once to each word in the event.
<P>

</DL>
<P>

<A NAME="Programming with GNU History"></A>
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<H1> 2. Programming with GNU History </H1>
<!--docid::SEC6::-->
<P>

This chapter describes how to interface programs that you write
with the GNU History Library.
It should be considered a technical guide.
For information on the interactive use of GNU History, see section <A HREF="history.html#SEC1">1. Using History Interactively</A>.
</P><P>

<BLOCKQUOTE><TABLE BORDER=0 CELLSPACING=0> 
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="history.html#SEC7">2.1 Introduction to History</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">What is the GNU History library for?</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="history.html#SEC8">2.2 History Storage</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">How information is stored.</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="history.html#SEC9">2.3 History Functions</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Functions that you can use.</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="history.html#SEC17">2.4 History Variables</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Variables that control behaviour.</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="history.html#SEC18">2.5 History Programming Example</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Example of using the GNU History Library.</TD></TR>
</TABLE></BLOCKQUOTE>
<P>

<A NAME="Introduction to History"></A>
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<H2> 2.1 Introduction to History </H2>
<!--docid::SEC7::-->
<P>

Many programs read input from the user a line at a time.  The GNU
History library is able to keep track of those lines, associate arbitrary
data with each line, and utilize information from previous lines in
composing new ones. 
</P><P>

The programmer using the History library has available functions
for remembering lines on a history list, associating arbitrary data
with a line, removing lines from the list, searching through the list
for a line containing an arbitrary text string, and referencing any line
in the list directly.  In addition, a history <EM>expansion</EM> function
is available which provides for a consistent user interface across
different programs.
</P><P>

The user 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>csh</CODE>.
</P><P>

If the programmer desires, he can 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>&#60;readline/history.h&#62;</CODE> in any file that uses the
History library's features.  It supplies extern declarations for all
of the library's public functions and variables, and declares all of
the public data structures.
</P><P>

<A NAME="History Storage"></A>
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<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_About"> ? </A>]</TD>
</TR></TABLE>
<H2> 2.2 History Storage </H2>
<!--docid::SEC8::-->
<P>

The history list is an array of history entries.  A history entry is
declared as follows:
</P><P>

<TABLE><tr><td>&nbsp;</td><td class=example><pre>typedef void *histdata_t;

typedef struct _hist_entry {
  char *line;
  char *timestamp;
  histdata_t data;
} HIST_ENTRY;
</pre></td></tr></table></P><P>

The history list itself might therefore be declared as
</P><P>

<TABLE><tr><td>&nbsp;</td><td class=example><pre>HIST_ENTRY **the_history_list;
</pre></td></tr></table></P><P>

The state of the History library is encapsulated into a single structure:
</P><P>

<TABLE><tr><td>&nbsp;</td><td class=example><pre>/*
 * 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></td></tr></table></P><P>

If the flags member includes <CODE>HS_STIFLED</CODE>, the history has been
stifled.
</P><P>

<A NAME="History Functions"></A>
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<H2> 2.3 History Functions </H2>
<!--docid::SEC9::-->
<P>

This section describes the calling sequence for the various functions
exported by the GNU History library.
</P><P>

<BLOCKQUOTE><TABLE BORDER=0 CELLSPACING=0> 
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="history.html#SEC10">2.3.1 Initializing History and State Management</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Functions to call when you
						want to use history in a
						program.</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="history.html#SEC11">2.3.2 History List Management</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Functions used to manage the list
					of history entries.</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="history.html#SEC12">2.3.3 Information About the History List</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Functions returning information about
					the history list.</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="history.html#SEC13">2.3.4 Moving Around the History List</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Functions used to change the position
					in the history list.</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="history.html#SEC14">2.3.5 Searching the History List</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Functions to search the history list
					for entries containing a string.</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="history.html#SEC15">2.3.6 Managing the History File</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Functions that read and write a file
					containing the history list.</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="history.html#SEC16">2.3.7 History Expansion</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Functions to perform csh-like history
					expansion.</TD></TR>
</TABLE></BLOCKQUOTE>
<P>

<A NAME="Initializing History and State Management"></A>
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</TR></TABLE>
<H3> 2.3.1 Initializing History and State Management </H3>
<!--docid::SEC10::-->
<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><P>

<A NAME="IDX2"></A>
<DL>
<DT><U>Function:</U> void <B>using_history</B> <I>(void)</I>
<DD>Begin a session in which the history functions might be used.  This
initializes the interactive variables.
</DL>
</P><P>

<A NAME="IDX3"></A>
<DL>
<DT><U>Function:</U> HISTORY_STATE * <B>history_get_history_state</B> <I>(void)</I>
<DD>Return a structure describing the current state of the input history.
</DL>
</P><P>

<A NAME="IDX4"></A>
<DL>
<DT><U>Function:</U> void <B>history_set_history_state</B> <I>(HISTORY_STATE *state)</I>
<DD>Set the state of the history list according to <VAR>state</VAR>.
</DL>
</P><P>

<A NAME="History List Management"></A>
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</TR></TABLE>
<H3> 2.3.2 History List Management </H3>
<!--docid::SEC11::-->
<P>

These functions manage individual entries on the history list, or set
parameters managing the list itself.
</P><P>

<A NAME="IDX5"></A>
<DL>
<DT><U>Function:</U> void <B>add_history</B> <I>(const char *string)</I>
<DD>Place <VAR>string</VAR> at the end of the history list.  The associated data
field (if any) is set to <CODE>NULL</CODE>.
</DL>
</P><P>

<A NAME="IDX6"></A>
<DL>
<DT><U>Function:</U> void <B>add_history_time</B> <I>(const char *string)</I>
<DD>Change the time stamp associated with the most recent history entry to
<VAR>string</VAR>.
</DL>
</P><P>

<A NAME="IDX7"></A>
<DL>
<DT><U>Function:</U> HIST_ENTRY * <B>remove_history</B> <I>(int which)</I>
<DD>Remove history entry at offset <VAR>which</VAR> from the history.  The
removed element is returned so you can free the line, data,
and containing structure.
</DL>
</P><P>

<A NAME="IDX8"></A>
<DL>
<DT><U>Function:</U> histdata_t <B>free_history_entry</B> <I>(HIST_ENTRY *histent)</I>
<DD>Free the history entry <VAR>histent</VAR> and any history library private
data associated with it.  Returns the application-specific data
so the caller can dispose of it.
</DL>
</P><P>

<A NAME="IDX9"></A>
<DL>
<DT><U>Function:</U> HIST_ENTRY * <B>replace_history_entry</B> <I>(int which, const char *line, histdata_t data)</I>
<DD>Make the history entry at offset <VAR>which</VAR> have <VAR>line</VAR> and <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>which</VAR>, a <CODE>NULL</CODE> pointer is returned.
</DL>
</P><P>

<A NAME="IDX10"></A>
<DL>
<DT><U>Function:</U> void <B>clear_history</B> <I>(void)</I>
<DD>Clear the history list by deleting all the entries.
</DL>
</P><P>

<A NAME="IDX11"></A>
<DL>
<DT><U>Function:</U> void <B>stifle_history</B> <I>(int max)</I>
<DD>Stifle the history list, remembering only the last <VAR>max</VAR> entries.
</DL>
</P><P>

<A NAME="IDX12"></A>
<DL>
<DT><U>Function:</U> int <B>unstifle_history</B> <I>(void)</I>
<DD>Stop stifling the history.  This returns the previously-set
maximum number of history entries (as set by <CODE>stifle_history()</CODE>).
The value is positive if the history was
stifled, negative if it wasn't.
</DL>
</P><P>

<A NAME="IDX13"></A>
<DL>
<DT><U>Function:</U> int <B>history_is_stifled</B> <I>(void)</I>
<DD>Returns non-zero if the history is stifled, zero if it is not.
</DL>
</P><P>

<A NAME="Information About the History List"></A>
<HR SIZE="6">
<A NAME="SEC12"></A>
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<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_About"> ? </A>]</TD>
</TR></TABLE>
<H3> 2.3.3 Information About the History List </H3>
<!--docid::SEC12::-->
<P>

These functions return information about the entire history list or
individual list entries.
</P><P>

<A NAME="IDX14"></A>
<DL>
<DT><U>Function:</U> HIST_ENTRY ** <B>history_list</B> <I>(void)</I>
<DD>Return a <CODE>NULL</CODE> terminated array of <CODE>HIST_ENTRY *</CODE> which is the
current input history.  Element 0 of this list is the beginning of time.
If there is no history, return <CODE>NULL</CODE>.
</DL>
</P><P>

<A NAME="IDX15"></A>
<DL>
<DT><U>Function:</U> int <B>where_history</B> <I>(void)</I>
<DD>Returns the offset of the current history element.
</DL>
</P><P>

<A NAME="IDX16"></A>
<DL>
<DT><U>Function:</U> HIST_ENTRY * <B>current_history</B> <I>(void)</I>
<DD>Return the history entry at the current position, as determined by
<CODE>where_history()</CODE>.  If there is no entry there, return a <CODE>NULL</CODE>
pointer.
</DL>
</P><P>

<A NAME="IDX17"></A>
<DL>
<DT><U>Function:</U> HIST_ENTRY * <B>history_get</B> <I>(int offset)</I>
<DD>Return the history entry at position <VAR>offset</VAR>, starting from
<CODE>history_base</CODE> (see section <A HREF="history.html#SEC17">2.4 History Variables</A>).
If there is no entry there, or if <VAR>offset</VAR>
is greater than the history length, return a <CODE>NULL</CODE> pointer.
</DL>
</P><P>

<A NAME="IDX18"></A>
<DL>
<DT><U>Function:</U> time_t <B>history_get_time</B> <I>(HIST_ENTRY *entry)</I>
<DD>Return the time stamp associated with the history entry <VAR>entry</VAR>.
</DL>
</P><P>

<A NAME="IDX19"></A>
<DL>
<DT><U>Function:</U> int <B>history_total_bytes</B> <I>(void)</I>
<DD>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.
</DL>
</P><P>

<A NAME="Moving Around the History List"></A>
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</TR></TABLE>
<H3> 2.3.4 Moving Around the History List </H3>
<!--docid::SEC13::-->
<P>

These functions allow the current index into the history list to be
set or changed.
</P><P>

<A NAME="IDX20"></A>
<DL>
<DT><U>Function:</U> int <B>history_set_pos</B> <I>(int pos)</I>
<DD>Set the current history offset to <VAR>pos</VAR>, an absolute index
into the list.
Returns 1 on success, 0 if <VAR>pos</VAR> is less than zero or greater
than the number of history entries.
</DL>
</P><P>

<A NAME="IDX21"></A>
<DL>
<DT><U>Function:</U> HIST_ENTRY * <B>previous_history</B> <I>(void)</I>
<DD>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
a <CODE>NULL</CODE> pointer.
</DL>
</P><P>

<A NAME="IDX22"></A>
<DL>
<DT><U>Function:</U> HIST_ENTRY * <B>next_history</B> <I>(void)</I>
<DD>Move the current history offset forward to the next history entry, and
return the a pointer to that entry.  If there is no next entry, return
a <CODE>NULL</CODE> pointer.
</DL>
</P><P>

<A NAME="Searching the History List"></A>
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</TR></TABLE>
<H3> 2.3.5 Searching the History List </H3>
<!--docid::SEC14::-->
<P>

These functions allow searching of 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>anchored</EM>,
meaning that the string must match at the beginning of the history entry.
<A NAME="IDX23"></A>
</P><P>

<A NAME="IDX24"></A>
<DL>
<DT><U>Function:</U> int <B>history_search</B> <I>(const char *string, int direction)</I>
<DD>Search the history for <VAR>string</VAR>, starting at the current history offset.
If <VAR>direction</VAR> is less than 0, then the search is through
previous entries, otherwise through subsequent entries.
If <VAR>string</VAR> is found, then
the current history index is set to that history entry, and the value
returned is the offset in the line of the entry where
<VAR>string</VAR> was found.  Otherwise, nothing is changed, and a -1 is
returned.
</DL>
</P><P>

<A NAME="IDX25"></A>
<DL>
<DT><U>Function:</U> int <B>history_search_prefix</B> <I>(const char *string, int direction)</I>
<DD>Search the history for <VAR>string</VAR>, starting at the current history
offset.  The search is anchored: matching lines must begin with
<VAR>string</VAR>.  If <VAR>direction</VAR> is less than 0, then the search is
through previous entries, otherwise through subsequent entries.
If <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 a -1 is returned. 
</DL>
</P><P>

<A NAME="IDX26"></A>
<DL>
<DT><U>Function:</U> int <B>history_search_pos</B> <I>(const char *string, int direction, int pos)</I>
<DD>Search for <VAR>string</VAR> in the history list, starting at <VAR>pos</VAR>, an
absolute index into the list.  If <VAR>direction</VAR> is negative, the search
proceeds backward from <VAR>pos</VAR>, otherwise forward.  Returns the absolute
index of the history element where <VAR>string</VAR> was found, or -1 otherwise.
</DL>
</P><P>

<A NAME="Managing the History File"></A>
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<A NAME="SEC15"></A>
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<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_About"> ? </A>]</TD>
</TR></TABLE>
<H3> 2.3.6 Managing the History File </H3>
<!--docid::SEC15::-->
<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><P>

<A NAME="IDX27"></A>
<DL>
<DT><U>Function:</U> int <B>read_history</B> <I>(const char *filename)</I>
<DD>Add the contents of <VAR>filename</VAR> to the history list, a line at a time.
If <VAR>filename</VAR> is <CODE>NULL</CODE>, then read from <TT>`~/.history'</TT>.
Returns 0 if successful, or <CODE>errno</CODE> if not.
</DL>
</P><P>

<A NAME="IDX28"></A>
<DL>
<DT><U>Function:</U> int <B>read_history_range</B> <I>(const char *filename, int from, int to)</I>
<DD>Read a range of lines from <VAR>filename</VAR>, adding them to the history list.
Start reading at line <VAR>from</VAR> and end at <VAR>to</VAR>.
If <VAR>from</VAR> is zero, start at the beginning.  If <VAR>to</VAR> is less than
<VAR>from</VAR>, then read until the end of the file.  If <VAR>filename</VAR> is
<CODE>NULL</CODE>, then read from <TT>`~/.history'</TT>.  Returns 0 if successful,
or <CODE>errno</CODE> if not.
</DL>
</P><P>

<A NAME="IDX29"></A>
<DL>
<DT><U>Function:</U> int <B>write_history</B> <I>(const char *filename)</I>
<DD>Write the current history to <VAR>filename</VAR>, overwriting <VAR>filename</VAR>
if necessary.
If <VAR>filename</VAR> is <CODE>NULL</CODE>, then write the history list to
<TT>`~/.history'</TT>.
Returns 0 on success, or <CODE>errno</CODE> on a read or write error.
</DL>
</P><P>

<A NAME="IDX30"></A>
<DL>
<DT><U>Function:</U> int <B>append_history</B> <I>(int nelements, const char *filename)</I>
<DD>Append the last <VAR>nelements</VAR> of the history list to <VAR>filename</VAR>.
If <VAR>filename</VAR> is <CODE>NULL</CODE>, then append to <TT>`~/.history'</TT>.
Returns 0 on success, or <CODE>errno</CODE> on a read or write error.
</DL>
</P><P>

<A NAME="IDX31"></A>
<DL>
<DT><U>Function:</U> int <B>history_truncate_file</B> <I>(const char *filename, int nlines)</I>
<DD>Truncate the history file <VAR>filename</VAR>, leaving only the last
<VAR>nlines</VAR> lines.
If <VAR>filename</VAR> is <CODE>NULL</CODE>, then <TT>`~/.history'</TT> is truncated.
Returns 0 on success, or <CODE>errno</CODE> on failure.
</DL>
</P><P>

<A NAME="History Expansion"></A>
<HR SIZE="6">
<A NAME="SEC16"></A>
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</TR></TABLE>
<H3> 2.3.7 History Expansion </H3>
<!--docid::SEC16::-->
<P>

These functions implement history expansion.
</P><P>

<A NAME="IDX32"></A>
<DL>
<DT><U>Function:</U> int <B>history_expand</B> <I>(char *string, char **output)</I>
<DD>Expand <VAR>string</VAR>, placing the result into <VAR>output</VAR>, a pointer
to a string (see section <A HREF="history.html#SEC2">1.1 History Expansion</A>).  Returns:
<DL COMPACT>
<DT><CODE>0</CODE>
<DD>If no expansions took place (or, if the only change in
the text was the removal of escape characters preceding the history expansion
character);
<DT><CODE>1</CODE>
<DD>if expansions did take place;
<DT><CODE>-1</CODE>
<DD>if there was an error in expansion;
<DT><CODE>2</CODE>
<DD>if the returned line should be displayed, but not executed,
as with the <CODE>:p</CODE> modifier (see section <A HREF="history.html#SEC5">1.1.3 Modifiers</A>).
</DL>
<P>

If an error ocurred in expansion, then <VAR>output</VAR> contains a descriptive
error message.
</DL>
</P><P>

<A NAME="IDX33"></A>
<DL>
<DT><U>Function:</U> char * <B>get_history_event</B> <I>(const char *string, int *cindex, int qchar)</I>
<DD>Returns the text of the history event beginning at <VAR>string</VAR> +
<VAR>*cindex</VAR>.  <VAR>*cindex</VAR> is modified to point to after the event
specifier.  At function entry, <VAR>cindex</VAR> points to the index into
<VAR>string</VAR> where the history event specification begins.  <VAR>qchar</VAR>
is a character that is allowed to end the event specification in addition
to the "normal" terminating characters.
</DL>
</P><P>

<A NAME="IDX34"></A>
<DL>
<DT><U>Function:</U> char ** <B>history_tokenize</B> <I>(const char *string)</I>
<DD>Return an array of tokens parsed out of <VAR>string</VAR>, much as the
shell might.  The tokens are split on the characters in the
<VAR>history_word_delimiters</VAR> variable,
and shell quoting conventions are obeyed.
</DL>
</P><P>

<A NAME="IDX35"></A>
<DL>
<DT><U>Function:</U> char * <B>history_arg_extract</B> <I>(int first, int last, const char *string)</I>
<DD>Extract a string segment consisting of the <VAR>first</VAR> through <VAR>last</VAR>
arguments present in <VAR>string</VAR>.  Arguments are split using
<CODE>history_tokenize</CODE>.
</DL>
</P><P>

<A NAME="History Variables"></A>
<HR SIZE="6">
<A NAME="SEC17"></A>
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<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_About"> ? </A>]</TD>
</TR></TABLE>
<H2> 2.4 History Variables </H2>
<!--docid::SEC17::-->
<P>

This section describes the externally-visible variables exported by
the GNU History Library.
</P><P>

<A NAME="IDX36"></A>
<DL>
<DT><U>Variable:</U> int <B>history_base</B>
<DD>The logical offset of the first entry in the history list.
</DL>
</P><P>

<A NAME="IDX37"></A>
<DL>
<DT><U>Variable:</U> int <B>history_length</B>
<DD>The number of entries currently stored in the history list.
</DL>
</P><P>

<A NAME="IDX38"></A>
<DL>
<DT><U>Variable:</U> int <B>history_max_entries</B>
<DD>The maximum number of history entries.  This must be changed using
<CODE>stifle_history()</CODE>.
</DL>
</P><P>

<A NAME="IDX39"></A>
<DL>
<DT><U>Variable:</U> int <B>history_write_timestamps</B>
<DD>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.
</DL>
</P><P>

<A NAME="IDX40"></A>
<DL>
<DT><U>Variable:</U> char <B>history_expansion_char</B>
<DD>The character that introduces a history event.  The default is <SAMP>`!'</SAMP>.
Setting this to 0 inhibits history expansion.
</DL>
</P><P>

<A NAME="IDX41"></A>
<DL>
<DT><U>Variable:</U> char <B>history_subst_char</B>
<DD>The character that invokes word substitution if found at the start of
a line.  The default is <SAMP>`^'</SAMP>.
</DL>
</P><P>

<A NAME="IDX42"></A>
<DL>
<DT><U>Variable:</U> char <B>history_comment_char</B>
<DD>During tokenization, if this character is seen 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.
</DL>
</P><P>

<A NAME="IDX43"></A>
<DL>
<DT><U>Variable:</U> char * <B>history_word_delimiters</B>
<DD>The characters that separate tokens for <CODE>history_tokenize()</CODE>.
The default value is <CODE>" \t\n()<>;&|"</CODE>.
</DL>
</P><P>

<A NAME="IDX44"></A>
<DL>
<DT><U>Variable:</U> char * <B>history_search_delimiter_chars</B>
<DD>The list of additional characters which can delimit a history search
string, in addition to space, TAB, <SAMP>`:'</SAMP> and <SAMP>`?'</SAMP> in the case of
a substring search.  The default is empty.
</DL>
</P><P>

<A NAME="IDX45"></A>
<DL>
<DT><U>Variable:</U> char * <B>history_no_expand_chars</B>
<DD>The list of characters which inhibit history expansion if found immediately
following <VAR>history_expansion_char</VAR>.  The default is space, tab, newline,
carriage return, and <SAMP>`='</SAMP>.
</DL>
</P><P>

<A NAME="IDX46"></A>
<DL>
<DT><U>Variable:</U> int <B>history_quotes_inhibit_expansion</B>
<DD>If non-zero, single-quoted words are not scanned for the history expansion
character.  The default value is 0.
</DL>
</P><P>

<A NAME="IDX47"></A>
<DL>
<DT><U>Variable:</U> rl_linebuf_func_t * <B>history_inhibit_expansion_function</B>
<DD>This should be set to the address of a function that takes two arguments:
a <CODE>char *</CODE> (<VAR>string</VAR>)
and an <CODE>int</CODE> index into that string (<VAR>i</VAR>).
It should return a non-zero value if the history expansion starting at
<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>NULL</CODE>.
</DL>
</P><P>

<A NAME="History Programming Example"></A>
<HR SIZE="6">
<A NAME="SEC18"></A>
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</TR></TABLE>
<H2> 2.5 History Programming Example </H2>
<!--docid::SEC18::-->
<P>

The following program demonstrates simple use of the GNU History Library.
</P><P>

<TABLE><tr><td>&nbsp;</td><td class=smallexample><FONT SIZE=-1><pre>#include &#60;stdio.h&#62;
#include &#60;readline/history.h&#62;

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

  line[0] = 0;

  using_history ();
  while (!done)
    {
      printf ("history$ ");
      fflush (stdout);
      t = fgets (line, sizeof (line) - 1, stdin);
      if (t &#38;&#38; *t)
        {
          len = strlen (t);
          if (t[len - 1] == '\n')
            t[len - 1] = '\0';
        }

      if (!t)
        strcpy (line, "quit");

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

          result = history_expand (line, &#38;expansion);
          if (result)
            fprintf (stderr, "%s\n", expansion);

          if (result &#60; 0 || result == 2)
            {
              free (expansion);
              continue;
            }

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

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

          the_list = history_list ();
          if (the_list)
            for (i = 0; the_list[i]; i++)
              printf ("%d: %s\n", i + history_base, the_list[i]-&#62;line);
        }
      else if (strncmp (line, "delete", 6) == 0)
        {
          int which;
          if ((sscanf (line + 6, "%d", &#38;which)) == 1)
            {
              HIST_ENTRY *entry = remove_history (which);
              if (!entry)
                fprintf (stderr, "No such entry %d\n", which);
              else
                {
                  free (entry-&#62;line);
                  free (entry);
                }
            }
          else
            {
              fprintf (stderr, "non-numeric arg given to `delete'\n");
            }
        }
    }
}
</FONT></pre></td></tr></table></P><P>

<A NAME="Copying This Manual"></A>
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<H1> A. Copying This Manual </H1>
<!--docid::SEC19::-->
<P>

<BLOCKQUOTE><TABLE BORDER=0 CELLSPACING=0> 
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="history.html#SEC20">A.1 GNU Free Documentation License</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">License for copying this manual.</TD></TR>
</TABLE></BLOCKQUOTE>
<P>

<A NAME="GNU Free Documentation License"></A>
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<H2> A.1 GNU Free Documentation License </H2>
<!--docid::SEC20::-->
<P>

<A NAME="IDX48"></A>
<center>
 Version 1.2, November 2002
</center>
</P><P>

<TABLE><tr><td>&nbsp;</td><td class=display><pre style="font-family: serif">Copyright (C) 2000,2001,2002 Free Software Foundation, Inc.
59 Temple Place, Suite 330, Boston, MA  02111-1307, USA

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

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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><P>

<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'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><P>

<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><P>

<OL>
<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.
<P>

<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.
<P>

<LI>
State on the Title page the name of the publisher of the
Modified Version, as the publisher.
<P>

<LI>
Preserve all the copyright notices of the Document.
<P>

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

<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.
<P>

<LI>
Preserve in that license notice the full lists of Invariant Sections
and required Cover Texts given in the Document's license notice.
<P>

<LI>
Include an unaltered copy of this License.
<P>

<LI>
Preserve the section Entitled "History", 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 "History" 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.
<P>

<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 "History" 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.
<P>

<LI>
For any section Entitled "Acknowledgements" or "Dedications", 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.
<P>

<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.
<P>

<LI>
Delete any section Entitled "Endorsements".  Such a section
may not be included in the Modified Version.
<P>

<LI>
Do not retitle any existing section to be Entitled "Endorsements" or
to conflict in title with any Invariant Section.
<P>

<LI>
Preserve any Warranty Disclaimers.
</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's license notice.
These titles must be distinct from any other section titles.
</P><P>

You may add a section Entitled "Endorsements", provided it contains
nothing but endorsements of your Modified Version by various
parties--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><P>

<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 "History"
in the various original documents, forming one section Entitled
"History"; likewise combine any sections Entitled "Acknowledgements",
and any sections Entitled "Dedications".  You must delete all
sections Entitled "Endorsements."
</P><P>

<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><P>

<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 "aggregate" if the copyright
resulting from the compilation is not used to limit the legal rights
of the compilation's users beyond what the individual works permit.
When the Document is included 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'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><P>

<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 "Acknowledgements",
"Dedications", or "History", the requirement (section 4) to Preserve
its Title (section 1) will typically require changing the actual
title.
</P><P>

<LI>
TERMINATION
<P>

You may not copy, modify, sublicense, or distribute the Document except
as expressly provided for under this License.  Any other attempt to
copy, modify, sublicense or distribute the Document is void, and will
automatically terminate your rights under this License.  However,
parties who have received copies, or rights, from you under this
License will not have their licenses terminated so long as such
parties remain in full compliance.
</P><P>

<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 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 "or any later version" 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.
</OL>
<P>

<HR SIZE="6">
<A NAME="SEC21"></A>
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<H3> A.1.1 ADDENDUM: How to use this License for your documents </H3>
<!--docid::SEC21::-->
<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><P>

<TABLE><tr><td>&nbsp;</td><td class=smallexample><FONT SIZE=-1><pre>  Copyright (C)  <VAR>year</VAR>  <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 1.2
  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''.
</FONT></pre></td></tr></table></P><P>

If you have Invariant Sections, Front-Cover Texts and Back-Cover Texts,
replace the "with...Texts." line with this:
</P><P>

<TABLE><tr><td>&nbsp;</td><td class=smallexample><FONT SIZE=-1><pre>    with the Invariant Sections being <VAR>list their titles</VAR>, with
    the Front-Cover Texts being <VAR>list</VAR>, and with the Back-Cover Texts
    being <VAR>list</VAR>.
</FONT></pre></td></tr></table></P><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><P>

<A NAME="Concept Index"></A>
<HR SIZE="6">
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<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_About"> ? </A>]</TD>
</TR></TABLE>
<H1> B. Concept Index </H1>
<!--docid::SEC22::-->
<table><tr><th valign=top>Jump to: &nbsp; </th><td><A HREF="history.html#cp_A" style="text-decoration:none"><b>A</b></A>
 &nbsp; 
<A HREF="history.html#cp_E" style="text-decoration:none"><b>E</b></A>
 &nbsp; 
<A HREF="history.html#cp_F" style="text-decoration:none"><b>F</b></A>
 &nbsp; 
<A HREF="history.html#cp_H" style="text-decoration:none"><b>H</b></A>
 &nbsp; 
</td></tr></table><br><P></P>
<TABLE border=0>
<TR><TD></TD><TH ALIGN=LEFT>Index Entry</TH><TH ALIGN=LEFT> Section</TH></TR>
<TR><TD COLSPAN=3> <HR></TD></TR>
<TR><TH><A NAME="cp_A"></A>A</TH><TD></TD><TD></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX23">anchored search</A></TD><TD valign=top><A HREF="history.html#SEC14">2.3.5 Searching the History List</A></TD></TR>
<TR><TD COLSPAN=3> <HR></TD></TR>
<TR><TH><A NAME="cp_E"></A>E</TH><TD></TD><TD></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#SEC3">event designators</A></TD><TD valign=top><A HREF="history.html#SEC3">1.1.1 Event Designators</A></TD></TR>
<TR><TD COLSPAN=3> <HR></TD></TR>
<TR><TH><A NAME="cp_F"></A>F</TH><TD></TD><TD></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX48">FDL, GNU Free Documentation License</A></TD><TD valign=top><A HREF="history.html#SEC20">A.1 GNU Free Documentation License</A></TD></TR>
<TR><TD COLSPAN=3> <HR></TD></TR>
<TR><TH><A NAME="cp_H"></A>H</TH><TD></TD><TD></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX1">history events</A></TD><TD valign=top><A HREF="history.html#SEC3">1.1.1 Event Designators</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#SEC2">history expansion</A></TD><TD valign=top><A HREF="history.html#SEC2">1.1 History Expansion</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#SEC14">History Searching</A></TD><TD valign=top><A HREF="history.html#SEC14">2.3.5 Searching the History List</A></TD></TR>
<TR><TD COLSPAN=3> <HR></TD></TR>
</TABLE><P></P><table><tr><th valign=top>Jump to: &nbsp; </th><td><A HREF="history.html#cp_A" style="text-decoration:none"><b>A</b></A>
 &nbsp; 
<A HREF="history.html#cp_E" style="text-decoration:none"><b>E</b></A>
 &nbsp; 
<A HREF="history.html#cp_F" style="text-decoration:none"><b>F</b></A>
 &nbsp; 
<A HREF="history.html#cp_H" style="text-decoration:none"><b>H</b></A>
 &nbsp; 
</td></tr></table><br><P>

<A NAME="Function and Variable Index"></A>
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<H1> C. Function and Variable Index </H1>
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 &nbsp; 
<A HREF="history.html#vr_C" style="text-decoration:none"><b>C</b></A>
 &nbsp; 
<A HREF="history.html#vr_F" style="text-decoration:none"><b>F</b></A>
 &nbsp; 
<A HREF="history.html#vr_G" style="text-decoration:none"><b>G</b></A>
 &nbsp; 
<A HREF="history.html#vr_H" style="text-decoration:none"><b>H</b></A>
 &nbsp; 
<A HREF="history.html#vr_N" style="text-decoration:none"><b>N</b></A>
 &nbsp; 
<A HREF="history.html#vr_P" style="text-decoration:none"><b>P</b></A>
 &nbsp; 
<A HREF="history.html#vr_R" style="text-decoration:none"><b>R</b></A>
 &nbsp; 
<A HREF="history.html#vr_S" style="text-decoration:none"><b>S</b></A>
 &nbsp; 
<A HREF="history.html#vr_U" style="text-decoration:none"><b>U</b></A>
 &nbsp; 
<A HREF="history.html#vr_W" style="text-decoration:none"><b>W</b></A>
 &nbsp; 
</td></tr></table><br><P></P>
<TABLE border=0>
<TR><TD></TD><TH ALIGN=LEFT>Index Entry</TH><TH ALIGN=LEFT> Section</TH></TR>
<TR><TD COLSPAN=3> <HR></TD></TR>
<TR><TH><A NAME="vr_A"></A>A</TH><TD></TD><TD></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX5"><CODE>add_history</CODE></A></TD><TD valign=top><A HREF="history.html#SEC11">2.3.2 History List Management</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX6"><CODE>add_history_time</CODE></A></TD><TD valign=top><A HREF="history.html#SEC11">2.3.2 History List Management</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX30"><CODE>append_history</CODE></A></TD><TD valign=top><A HREF="history.html#SEC15">2.3.6 Managing the History File</A></TD></TR>
<TR><TD COLSPAN=3> <HR></TD></TR>
<TR><TH><A NAME="vr_C"></A>C</TH><TD></TD><TD></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX10"><CODE>clear_history</CODE></A></TD><TD valign=top><A HREF="history.html#SEC11">2.3.2 History List Management</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX16"><CODE>current_history</CODE></A></TD><TD valign=top><A HREF="history.html#SEC12">2.3.3 Information About the History List</A></TD></TR>
<TR><TD COLSPAN=3> <HR></TD></TR>
<TR><TH><A NAME="vr_F"></A>F</TH><TD></TD><TD></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX8"><CODE>free_history_entry</CODE></A></TD><TD valign=top><A HREF="history.html#SEC11">2.3.2 History List Management</A></TD></TR>
<TR><TD COLSPAN=3> <HR></TD></TR>
<TR><TH><A NAME="vr_G"></A>G</TH><TD></TD><TD></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX33"><CODE>get_history_event</CODE></A></TD><TD valign=top><A HREF="history.html#SEC16">2.3.7 History Expansion</A></TD></TR>
<TR><TD COLSPAN=3> <HR></TD></TR>
<TR><TH><A NAME="vr_H"></A>H</TH><TD></TD><TD></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX35"><CODE>history_arg_extract</CODE></A></TD><TD valign=top><A HREF="history.html#SEC16">2.3.7 History Expansion</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX36"><CODE>history_base</CODE></A></TD><TD valign=top><A HREF="history.html#SEC17">2.4 History Variables</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX42"><CODE>history_comment_char</CODE></A></TD><TD valign=top><A HREF="history.html#SEC17">2.4 History Variables</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX32"><CODE>history_expand</CODE></A></TD><TD valign=top><A HREF="history.html#SEC16">2.3.7 History Expansion</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX40"><CODE>history_expansion_char</CODE></A></TD><TD valign=top><A HREF="history.html#SEC17">2.4 History Variables</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX17"><CODE>history_get</CODE></A></TD><TD valign=top><A HREF="history.html#SEC12">2.3.3 Information About the History List</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX3"><CODE>history_get_history_state</CODE></A></TD><TD valign=top><A HREF="history.html#SEC10">2.3.1 Initializing History and State Management</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX18"><CODE>history_get_time</CODE></A></TD><TD valign=top><A HREF="history.html#SEC12">2.3.3 Information About the History List</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX47"><CODE>history_inhibit_expansion_function</CODE></A></TD><TD valign=top><A HREF="history.html#SEC17">2.4 History Variables</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX13"><CODE>history_is_stifled</CODE></A></TD><TD valign=top><A HREF="history.html#SEC11">2.3.2 History List Management</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX37"><CODE>history_length</CODE></A></TD><TD valign=top><A HREF="history.html#SEC17">2.4 History Variables</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX14"><CODE>history_list</CODE></A></TD><TD valign=top><A HREF="history.html#SEC12">2.3.3 Information About the History List</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX38"><CODE>history_max_entries</CODE></A></TD><TD valign=top><A HREF="history.html#SEC17">2.4 History Variables</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX45"><CODE>history_no_expand_chars</CODE></A></TD><TD valign=top><A HREF="history.html#SEC17">2.4 History Variables</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX46"><CODE>history_quotes_inhibit_expansion</CODE></A></TD><TD valign=top><A HREF="history.html#SEC17">2.4 History Variables</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX24"><CODE>history_search</CODE></A></TD><TD valign=top><A HREF="history.html#SEC14">2.3.5 Searching the History List</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX44"><CODE>history_search_delimiter_chars</CODE></A></TD><TD valign=top><A HREF="history.html#SEC17">2.4 History Variables</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX26"><CODE>history_search_pos</CODE></A></TD><TD valign=top><A HREF="history.html#SEC14">2.3.5 Searching the History List</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX25"><CODE>history_search_prefix</CODE></A></TD><TD valign=top><A HREF="history.html#SEC14">2.3.5 Searching the History List</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX4"><CODE>history_set_history_state</CODE></A></TD><TD valign=top><A HREF="history.html#SEC10">2.3.1 Initializing History and State Management</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX20"><CODE>history_set_pos</CODE></A></TD><TD valign=top><A HREF="history.html#SEC13">2.3.4 Moving Around the History List</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX41"><CODE>history_subst_char</CODE></A></TD><TD valign=top><A HREF="history.html#SEC17">2.4 History Variables</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX34"><CODE>history_tokenize</CODE></A></TD><TD valign=top><A HREF="history.html#SEC16">2.3.7 History Expansion</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX19"><CODE>history_total_bytes</CODE></A></TD><TD valign=top><A HREF="history.html#SEC12">2.3.3 Information About the History List</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX31"><CODE>history_truncate_file</CODE></A></TD><TD valign=top><A HREF="history.html#SEC15">2.3.6 Managing the History File</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX43"><CODE>history_word_delimiters</CODE></A></TD><TD valign=top><A HREF="history.html#SEC17">2.4 History Variables</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX39"><CODE>history_write_timestamps</CODE></A></TD><TD valign=top><A HREF="history.html#SEC17">2.4 History Variables</A></TD></TR>
<TR><TD COLSPAN=3> <HR></TD></TR>
<TR><TH><A NAME="vr_N"></A>N</TH><TD></TD><TD></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX22"><CODE>next_history</CODE></A></TD><TD valign=top><A HREF="history.html#SEC13">2.3.4 Moving Around the History List</A></TD></TR>
<TR><TD COLSPAN=3> <HR></TD></TR>
<TR><TH><A NAME="vr_P"></A>P</TH><TD></TD><TD></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX21"><CODE>previous_history</CODE></A></TD><TD valign=top><A HREF="history.html#SEC13">2.3.4 Moving Around the History List</A></TD></TR>
<TR><TD COLSPAN=3> <HR></TD></TR>
<TR><TH><A NAME="vr_R"></A>R</TH><TD></TD><TD></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX27"><CODE>read_history</CODE></A></TD><TD valign=top><A HREF="history.html#SEC15">2.3.6 Managing the History File</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX28"><CODE>read_history_range</CODE></A></TD><TD valign=top><A HREF="history.html#SEC15">2.3.6 Managing the History File</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX7"><CODE>remove_history</CODE></A></TD><TD valign=top><A HREF="history.html#SEC11">2.3.2 History List Management</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX9"><CODE>replace_history_entry</CODE></A></TD><TD valign=top><A HREF="history.html#SEC11">2.3.2 History List Management</A></TD></TR>
<TR><TD COLSPAN=3> <HR></TD></TR>
<TR><TH><A NAME="vr_S"></A>S</TH><TD></TD><TD></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX11"><CODE>stifle_history</CODE></A></TD><TD valign=top><A HREF="history.html#SEC11">2.3.2 History List Management</A></TD></TR>
<TR><TD COLSPAN=3> <HR></TD></TR>
<TR><TH><A NAME="vr_U"></A>U</TH><TD></TD><TD></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX12"><CODE>unstifle_history</CODE></A></TD><TD valign=top><A HREF="history.html#SEC11">2.3.2 History List Management</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX2"><CODE>using_history</CODE></A></TD><TD valign=top><A HREF="history.html#SEC10">2.3.1 Initializing History and State Management</A></TD></TR>
<TR><TD COLSPAN=3> <HR></TD></TR>
<TR><TH><A NAME="vr_W"></A>W</TH><TD></TD><TD></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX15"><CODE>where_history</CODE></A></TD><TD valign=top><A HREF="history.html#SEC12">2.3.3 Information About the History List</A></TD></TR>
<TR><TD></TD><TD valign=top><A HREF="history.html#IDX29"><CODE>write_history</CODE></A></TD><TD valign=top><A HREF="history.html#SEC15">2.3.6 Managing the History File</A></TD></TR>
<TR><TD COLSPAN=3> <HR></TD></TR>
</TABLE><P></P><table><tr><th valign=top>Jump to: &nbsp; </th><td><A HREF="history.html#vr_A" style="text-decoration:none"><b>A</b></A>
 &nbsp; 
<A HREF="history.html#vr_C" style="text-decoration:none"><b>C</b></A>
 &nbsp; 
<A HREF="history.html#vr_F" style="text-decoration:none"><b>F</b></A>
 &nbsp; 
<A HREF="history.html#vr_G" style="text-decoration:none"><b>G</b></A>
 &nbsp; 
<A HREF="history.html#vr_H" style="text-decoration:none"><b>H</b></A>
 &nbsp; 
<A HREF="history.html#vr_N" style="text-decoration:none"><b>N</b></A>
 &nbsp; 
<A HREF="history.html#vr_P" style="text-decoration:none"><b>P</b></A>
 &nbsp; 
<A HREF="history.html#vr_R" style="text-decoration:none"><b>R</b></A>
 &nbsp; 
<A HREF="history.html#vr_S" style="text-decoration:none"><b>S</b></A>
 &nbsp; 
<A HREF="history.html#vr_U" style="text-decoration:none"><b>U</b></A>
 &nbsp; 
<A HREF="history.html#vr_W" style="text-decoration:none"><b>W</b></A>
 &nbsp; 
</td></tr></table><br><P>

<HR SIZE="6">
<A NAME="SEC_Contents"></A>
<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
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<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_About"> ? </A>]</TD>
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<H1>Table of Contents</H1>
<UL>
<A NAME="TOC1" HREF="history.html#SEC1">1. Using History Interactively</A>
<BR>
<UL>
<A NAME="TOC2" HREF="history.html#SEC2">1.1 History Expansion</A>
<BR>
<UL>
<A NAME="TOC3" HREF="history.html#SEC3">1.1.1 Event Designators</A>
<BR>
<A NAME="TOC4" HREF="history.html#SEC4">1.1.2 Word Designators</A>
<BR>
<A NAME="TOC5" HREF="history.html#SEC5">1.1.3 Modifiers</A>
<BR>
</UL>
</UL>
<A NAME="TOC6" HREF="history.html#SEC6">2. Programming with GNU History</A>
<BR>
<UL>
<A NAME="TOC7" HREF="history.html#SEC7">2.1 Introduction to History</A>
<BR>
<A NAME="TOC8" HREF="history.html#SEC8">2.2 History Storage</A>
<BR>
<A NAME="TOC9" HREF="history.html#SEC9">2.3 History Functions</A>
<BR>
<UL>
<A NAME="TOC10" HREF="history.html#SEC10">2.3.1 Initializing History and State Management</A>
<BR>
<A NAME="TOC11" HREF="history.html#SEC11">2.3.2 History List Management</A>
<BR>
<A NAME="TOC12" HREF="history.html#SEC12">2.3.3 Information About the History List</A>
<BR>
<A NAME="TOC13" HREF="history.html#SEC13">2.3.4 Moving Around the History List</A>
<BR>
<A NAME="TOC14" HREF="history.html#SEC14">2.3.5 Searching the History List</A>
<BR>
<A NAME="TOC15" HREF="history.html#SEC15">2.3.6 Managing the History File</A>
<BR>
<A NAME="TOC16" HREF="history.html#SEC16">2.3.7 History Expansion</A>
<BR>
</UL>
<A NAME="TOC17" HREF="history.html#SEC17">2.4 History Variables</A>
<BR>
<A NAME="TOC18" HREF="history.html#SEC18">2.5 History Programming Example</A>
<BR>
</UL>
<A NAME="TOC19" HREF="history.html#SEC19">A. Copying This Manual</A>
<BR>
<UL>
<A NAME="TOC20" HREF="history.html#SEC20">A.1 GNU Free Documentation License</A>
<BR>
<UL>
<A NAME="TOC21" HREF="history.html#SEC21">A.1.1 ADDENDUM: How to use this License for your documents</A>
<BR>
</UL>
</UL>
<A NAME="TOC22" HREF="history.html#SEC22">B. Concept Index</A>
<BR>
<A NAME="TOC23" HREF="history.html#SEC23">C. Function and Variable Index</A>
<BR>
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<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC22">Index</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="history.html#SEC_About"> ? </A>]</TD>
</TR></TABLE>
<H1>Short Table of Contents</H1>
<BLOCKQUOTE>
<A NAME="TOC1" HREF="history.html#SEC1">1. Using History Interactively</A>
<BR>
<A NAME="TOC6" HREF="history.html#SEC6">2. Programming with GNU History</A>
<BR>
<A NAME="TOC19" HREF="history.html#SEC19">A. Copying This Manual</A>
<BR>
<A NAME="TOC22" HREF="history.html#SEC22">B. Concept Index</A>
<BR>
<A NAME="TOC23" HREF="history.html#SEC23">C. Function and Variable Index</A>
<BR>

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<H1>About this document</H1>
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