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diff readline/doc/history.html @ 2996:9d4e3a9de17e
[project @ 1997-05-22 20:58:07 by jwe]
| author | jwe |
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| date | Thu, 22 May 1997 20:59:27 +0000 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/readline/doc/history.html Thu May 22 20:59:27 1997 +0000 @@ -0,0 +1,1062 @@ +<HTML> +<HEAD> +<!-- This HTML file has been created by texi2html 1.51 + from /usr/homes/chet/src/bash/readline-src/doc/hist.texinfo on 16 April 1997 --> + +<TITLE>GNU History Library</TITLE> +</HEAD> +<BODY> +<H1>GNU History Library</H1> +<H2>Edition 2.1, for <CODE>History Library</CODE> Version 2.1.</H2> +<H2>March 1996</H2> +<ADDRESS>Brian Fox, Free Software Foundation</ADDRESS> +<ADDRESS>Chet Ramey, Case Western Reserve University</ADDRESS> +<P> +<P><HR><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> +Published by the Free Software Foundation <BR> +675 Massachusetts Avenue, <BR> +Cambridge, MA 02139 USA + +</P> +<P> +Permission is granted to make and distribute verbatim copies of +this manual provided the copyright notice and this permission notice +are preserved on all copies. + +</P> +<P> +Permission is granted to copy and distribute modified versions of this +manual under the conditions for verbatim copying, provided that the entire +resulting derived work is distributed under the terms of a permission +notice identical to this one. + +</P> +<P> +Permission is granted to copy and distribute translations of this manual +into another language, under the above conditions for modified versions, +except that this permission notice may be stated in a translation approved +by the Foundation. + +</P> +<P> +Copyright (C) 1989, 1991 Free Software Foundation, Inc. + +</P> + + + +<H1><A NAME="SEC1" HREF="history_toc.html#TOC1">Using History Interactively</A></H1> + +<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">Programming with GNU History</A>. + +</P> + + + +<H2><A NAME="SEC2" HREF="history_toc.html#TOC2">Interactive History Expansion</A></H2> +<P> +<A NAME="IDX1"></A> + +</P> +<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 previous history 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 previous history is called the +<STRONG>event</STRONG>, and the portions of that line that are acted upon are +called <STRONG>words</STRONG>. Various <STRONG>modifiers</STRONG> are available to manipulate +the selected words. The line is broken into words in the same fashion +that Bash does, so that several English (or Unix) words +surrounded by quotes are considered as one word. +History expansions are introduced by the appearance of the +history expansion character, which is <SAMP>`!'</SAMP> by default. + +</P> + + + +<H3><A NAME="SEC3" HREF="history_toc.html#TOC3">Event Designators</A></H3> +<P> +<A NAME="IDX2"></A> + +</P> +<P> +An event designator is a reference to a command line entry in the +history list. +<A NAME="IDX3"></A> + +</P> +<DL COMPACT> + +<DT><CODE>!</CODE> +<DD> +Start a history substitution, except when followed by a space, tab, +the end of the line, <KBD>=</KBD> or <KBD>(</KBD>. + +<DT><CODE>!<VAR>n</VAR></CODE> +<DD> +Refer to command line <VAR>n</VAR>. + +<DT><CODE>!-<VAR>n</VAR></CODE> +<DD> +Refer to the command <VAR>n</VAR> lines back. + +<DT><CODE>!!</CODE> +<DD> +Refer to the previous command. This is a synonym for <SAMP>`!-1'</SAMP>. + +<DT><CODE>!<VAR>string</VAR></CODE> +<DD> +Refer to the most recent command starting with <VAR>string</VAR>. + +<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. + +<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>. + +<DT><CODE>!#</CODE> +<DD> +The entire command line typed so far. + +</DL> + + + +<H3><A NAME="SEC4" HREF="history_toc.html#TOC4">Word Designators</A></H3> + +<P> +Word designators are used to select desired words from the event. +A <SAMP>`:'</SAMP> separates the event specification from the word designator. It +can be omitted if the word designator begins with a <SAMP>`^'</SAMP>, <SAMP>`$'</SAMP>, +<SAMP>`*'</SAMP>, <SAMP>`-'</SAMP>, or <SAMP>`%'</SAMP>. Words are numbered from the beginning +of the line, with the first word being denoted by 0 (zero). Words are +inserted into the current line separated by single spaces. + +</P> +<DL COMPACT> + +<DT><CODE>0 (zero)</CODE> +<DD> +The <CODE>0</CODE>th word. For many applications, this is the command word. + +<DT><CODE><VAR>n</VAR></CODE> +<DD> +The <VAR>n</VAR>th word. + +<DT><CODE>^</CODE> +<DD> +The first argument; that is, word 1. + +<DT><CODE>$</CODE> +<DD> +The last argument. + +<DT><CODE>%</CODE> +<DD> +The word matched by the most recent <SAMP>`?<VAR>string</VAR>?'</SAMP> search. + +<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>. + +<DT><CODE>*</CODE> +<DD> +All of the words, except the <CODE>0</CODE>th. This is a synonym for <SAMP>`1-$'</SAMP>. +It is not an error to use <SAMP>`*'</SAMP> if there is just one word in the event; +the empty string is returned in that case. + +<DT><CODE><VAR>x</VAR>*</CODE> +<DD> +Abbreviates <SAMP>`<VAR>x</VAR>-$'</SAMP> + +<DT><CODE><VAR>x</VAR>-</CODE> +<DD> +Abbreviates <SAMP>`<VAR>x</VAR>-$'</SAMP> like <SAMP>`<VAR>x</VAR>*'</SAMP>, but omits the last word. + +</DL> + +<P> +If a word designator is supplied without an event specification, the +previous command is used as the event. + +</P> + + +<H3><A NAME="SEC5" HREF="history_toc.html#TOC5">Modifiers</A></H3> + +<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> +<DL COMPACT> + +<DT><CODE>h</CODE> +<DD> +Remove a trailing pathname component, leaving only the head. + +<DT><CODE>t</CODE> +<DD> +Remove all leading pathname components, leaving the tail. + +<DT><CODE>r</CODE> +<DD> +Remove a trailing suffix of the form <SAMP>`.<VAR>suffix</VAR>'</SAMP>, leaving +the basename. + +<DT><CODE>e</CODE> +<DD> +Remove all but the trailing suffix. + +<DT><CODE>p</CODE> +<DD> +Print the new command but do not execute it. + +<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>`&'</SAMP> appears in <VAR>new</VAR>, +it is replaced by <VAR>old</VAR>. A single backslash will quote +the <SAMP>`&'</SAMP>. The final delimiter is optional if it is the last +character on the input line. + +<DT><CODE>&</CODE> +<DD> +Repeat the previous substitution. + +<DT><CODE>g</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>`&'</SAMP>. + +</DL> + + + +<H1><A NAME="SEC6" HREF="history_toc.html#TOC6">Programming with GNU History</A></H1> + +<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">Using History Interactively</A>. + +</P> + + + +<H2><A NAME="SEC7" HREF="history_toc.html#TOC7">Introduction to History</A></H2> + +<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 <STRONG>expansion</STRONG> 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> + + +<H2><A NAME="SEC8" HREF="history_toc.html#TOC8">History Storage</A></H2> + +<P> +The history list is an array of history entries. A history entry is +declared as follows: + +</P> + +<PRE> +typedef struct _hist_entry { + char *line; + char *data; +} HIST_ENTRY; +</PRE> + +<P> +The history list itself might therefore be declared as + +</P> + +<PRE> +HIST_ENTRY **the_history_list; +</PRE> + +<P> +The state of the History library is encapsulated into a single structure: + +</P> + +<PRE> +/* A structure used to pass the current state of the history stuff around. */ +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> + +<P> +If the flags member includes <CODE>HS_STIFLED</CODE>, the history has been +stifled. + +</P> + + +<H2><A NAME="SEC9" HREF="history_toc.html#TOC9">History Functions</A></H2> + +<P> +This section describes the calling sequence for the various functions +present in GNU History. + +</P> + + + +<H3><A NAME="SEC10" HREF="history_toc.html#TOC10">Initializing History and State Management</A></H3> + +<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> +<DL> +<DT><U>Function:</U> void <B>using_history</B> <I>()</I> +<DD><A NAME="IDX4"></A> +Begin a session in which the history functions might be used. This +initializes the interactive variables. +</DL> + +</P> +<P> +<DL> +<DT><U>Function:</U> HISTORY_STATE * <B>history_get_history_state</B> <I>()</I> +<DD><A NAME="IDX5"></A> +Return a structure describing the current state of the input history. +</DL> + +</P> +<P> +<DL> +<DT><U>Function:</U> void <B>history_set_history_state</B> <I>(HISTORY_STATE *state)</I> +<DD><A NAME="IDX6"></A> +Set the state of the history list according to <VAR>state</VAR>. +</DL> + +</P> + + +<H3><A NAME="SEC11" HREF="history_toc.html#TOC11">History List Management</A></H3> + +<P> +These functions manage individual entries on the history list, or set +parameters managing the list itself. + +</P> +<P> +<DL> +<DT><U>Function:</U> void <B>add_history</B> <I>(char *string)</I> +<DD><A NAME="IDX7"></A> +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> +<DL> +<DT><U>Function:</U> HIST_ENTRY * <B>remove_history</B> <I>(int which)</I> +<DD><A NAME="IDX8"></A> +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> +<DL> +<DT><U>Function:</U> HIST_ENTRY * <B>replace_history_entry</B> <I>(int which, char *line, char *data)</I> +<DD><A NAME="IDX9"></A> +Make the history entry at offset <VAR>which</VAR> have <VAR>line</VAR> and <VAR>data</VAR>. +This returns the old entry so you can dispose of the data. In the case +of an invalid <VAR>which</VAR>, a <CODE>NULL</CODE> pointer is returned. +</DL> + +</P> +<P> +<DL> +<DT><U>Function:</U> void <B>clear_history</B> <I>()</I> +<DD><A NAME="IDX10"></A> +Clear the history list by deleting all the entries. +</DL> + +</P> +<P> +<DL> +<DT><U>Function:</U> void <B>stifle_history</B> <I>(int max)</I> +<DD><A NAME="IDX11"></A> +Stifle the history list, remembering only the last <VAR>max</VAR> entries. +</DL> + +</P> +<P> +<DL> +<DT><U>Function:</U> int <B>unstifle_history</B> <I>()</I> +<DD><A NAME="IDX12"></A> +Stop stifling the history. This returns the previous amount the +history was stifled. The value is positive if the history was +stifled, negative if it wasn't. +</DL> + +</P> +<P> +<DL> +<DT><U>Function:</U> int <B>history_is_stifled</B> <I>()</I> +<DD><A NAME="IDX13"></A> +Returns non-zero if the history is stifled, zero if it is not. +</DL> + +</P> + + +<H3><A NAME="SEC12" HREF="history_toc.html#TOC12">Information About the History List</A></H3> + +<P> +These functions return information about the entire history list or +individual list entries. + +</P> +<P> +<DL> +<DT><U>Function:</U> HIST_ENTRY ** <B>history_list</B> <I>()</I> +<DD><A NAME="IDX14"></A> +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> +<DL> +<DT><U>Function:</U> int <B>where_history</B> <I>()</I> +<DD><A NAME="IDX15"></A> +Returns the offset of the current history element. +</DL> + +</P> +<P> +<DL> +<DT><U>Function:</U> HIST_ENTRY * <B>current_history</B> <I>()</I> +<DD><A NAME="IDX16"></A> +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> +<DL> +<DT><U>Function:</U> HIST_ENTRY * <B>history_get</B> <I>(int offset)</I> +<DD><A NAME="IDX17"></A> +Return the history entry at position <VAR>offset</VAR>, starting from +<CODE>history_base</CODE>. 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> +<DL> +<DT><U>Function:</U> int <B>history_total_bytes</B> <I>()</I> +<DD><A NAME="IDX18"></A> +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> + + +<H3><A NAME="SEC13" HREF="history_toc.html#TOC13">Moving Around the History List</A></H3> + +<P> +These functions allow the current index into the history list to be +set or changed. + +</P> +<P> +<DL> +<DT><U>Function:</U> int <B>history_set_pos</B> <I>(int pos)</I> +<DD><A NAME="IDX19"></A> +Set the position in the history list to <VAR>pos</VAR>, an absolute index +into the list. +</DL> + +</P> +<P> +<DL> +<DT><U>Function:</U> HIST_ENTRY * <B>previous_history</B> <I>()</I> +<DD><A NAME="IDX20"></A> +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> +<DL> +<DT><U>Function:</U> HIST_ENTRY * <B>next_history</B> <I>()</I> +<DD><A NAME="IDX21"></A> +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> + + +<H3><A NAME="SEC14" HREF="history_toc.html#TOC14">Searching the History List</A></H3> +<P> +<A NAME="IDX22"></A> + +</P> +<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 <STRONG>anchored</STRONG>, +meaning that the string must match at the beginning of the history entry. +<A NAME="IDX23"></A> + +</P> +<P> +<DL> +<DT><U>Function:</U> int <B>history_search</B> <I>(char *string, int direction)</I> +<DD><A NAME="IDX24"></A> +Search the history for <VAR>string</VAR>, starting at the current history +offset. If <VAR>direction</VAR> < 0, then the search is through previous entries, +else through subsequent. 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> +<DL> +<DT><U>Function:</U> int <B>history_search_prefix</B> <I>(char *string, int direction)</I> +<DD><A NAME="IDX25"></A> +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> < 0, then the search is through previous +entries, else through subsequent. 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> +<DL> +<DT><U>Function:</U> int <B>history_search_pos</B> <I>(char *string, int direction, int pos)</I> +<DD><A NAME="IDX26"></A> +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> + + +<H3><A NAME="SEC15" HREF="history_toc.html#TOC15">Managing the History File</A></H3> + +<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> +<DL> +<DT><U>Function:</U> int <B>read_history</B> <I>(char *filename)</I> +<DD><A NAME="IDX27"></A> +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 errno if not. +</DL> + +</P> +<P> +<DL> +<DT><U>Function:</U> int <B>read_history_range</B> <I>(char *filename, int from, int to)</I> +<DD><A NAME="IDX28"></A> +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> +<DL> +<DT><U>Function:</U> int <B>write_history</B> <I>(char *filename)</I> +<DD><A NAME="IDX29"></A> +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>. Values +returned are as in <CODE>read_history ()</CODE>. +</DL> + +</P> +<P> +<DL> +<DT><U>Function:</U> int <B>append_history</B> <I>(int nelements, char *filename)</I> +<DD><A NAME="IDX30"></A> +Append the last <VAR>nelements</VAR> of the history list to <VAR>filename</VAR>. +</DL> + +</P> +<P> +<DL> +<DT><U>Function:</U> int <B>history_truncate_file</B> <I>(char *filename, int nlines)</I> +<DD><A NAME="IDX31"></A> +Truncate the history file <VAR>filename</VAR>, leaving only the last +<VAR>nlines</VAR> lines. +</DL> + +</P> + + +<H3><A NAME="SEC16" HREF="history_toc.html#TOC16">History Expansion</A></H3> + +<P> +These functions implement <CODE>csh</CODE>-like history expansion. + +</P> +<P> +<DL> +<DT><U>Function:</U> int <B>history_expand</B> <I>(char *string, char **output)</I> +<DD><A NAME="IDX32"></A> +Expand <VAR>string</VAR>, placing the result into <VAR>output</VAR>, a pointer +to a string (see section <A HREF="history.html#SEC2">Interactive 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 de-slashifying of 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 only be displayed, but not executed, +as with the <CODE>:p</CODE> modifier (see section <A HREF="history.html#SEC5">Modifiers</A>). +</DL> + +<P> +If an error ocurred in expansion, then <VAR>output</VAR> contains a descriptive +error message. +</DL> + +</P> +<P> +<DL> +<DT><U>Function:</U> char * <B>history_arg_extract</B> <I>(int first, int last, char *string)</I> +<DD><A NAME="IDX33"></A> +Extract a string segment consisting of the <VAR>first</VAR> through <VAR>last</VAR> +arguments present in <VAR>string</VAR>. Arguments are broken up as in Bash. +</DL> + +</P> +<P> +<DL> +<DT><U>Function:</U> char * <B>get_history_event</B> <I>(char *string, int *cindex, int qchar)</I> +<DD><A NAME="IDX34"></A> +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> +<DL> +<DT><U>Function:</U> char ** <B>history_tokenize</B> <I>(char *string)</I> +<DD><A NAME="IDX35"></A> +Return an array of tokens parsed out of <VAR>string</VAR>, much as the +shell might. The tokens are split on white space and on the +characters <CODE>()<>;&|$</CODE>, and shell quoting conventions are +obeyed. +</DL> + +</P> + + +<H2><A NAME="SEC17" HREF="history_toc.html#TOC17">History Variables</A></H2> + +<P> +This section describes the externally visible variables exported by +the GNU History Library. + +</P> +<P> +<DL> +<DT><U>Variable:</U> int <B>history_base</B> +<DD><A NAME="IDX36"></A> +The logical offset of the first entry in the history list. +</DL> + +</P> +<P> +<DL> +<DT><U>Variable:</U> int <B>history_length</B> +<DD><A NAME="IDX37"></A> +The number of entries currently stored in the history list. +</DL> + +</P> +<P> +<DL> +<DT><U>Variable:</U> int <B>max_input_history</B> +<DD><A NAME="IDX38"></A> +The maximum number of history entries. This must be changed using +<CODE>stifle_history ()</CODE>. +</DL> + +</P> +<P> +<DL> +<DT><U>Variable:</U> char <B>history_expansion_char</B> +<DD><A NAME="IDX39"></A> +The character that starts a history event. The default is <SAMP>`!'</SAMP>. +</DL> + +</P> +<P> +<DL> +<DT><U>Variable:</U> char <B>history_subst_char</B> +<DD><A NAME="IDX40"></A> +The character that invokes word substitution if found at the start of +a line. The default is <SAMP>`^'</SAMP>. +</DL> + +</P> +<P> +<DL> +<DT><U>Variable:</U> char <B>history_comment_char</B> +<DD><A NAME="IDX41"></A> +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> +<DL> +<DT><U>Variable:</U> char * <B>history_no_expand_chars</B> +<DD><A NAME="IDX42"></A> +The list of characters which inhibit history expansion if found immediately +following <VAR>history_expansion_char</VAR>. The default is whitespace and +<SAMP>`='</SAMP>. +</DL> + +</P> +<P> +<DL> +<DT><U>Variable:</U> char * <B>history_search_delimiter_chars</B> +<DD><A NAME="IDX43"></A> +The list of additional characters which can delimit a history search +string, in addition to whitespace, <SAMP>`:'</SAMP> and <SAMP>`?'</SAMP> in the case of +a substring search. The default is empty. +</DL> + +</P> +<P> +<DL> +<DT><U>Variable:</U> int <B>history_quotes_inhibit_expansion</B> +<DD><A NAME="IDX44"></A> +If non-zero, single-quoted words are not scanned for the history expansion +character. The default value is 0. +</DL> + +</P> +<P> +<DL> +<DT><U>Variable:</U> Function * <B>history_inhibit_expansion_function</B> +<DD><A NAME="IDX45"></A> +This should be set to the address of a function that takes two arguments: +a <CODE>char *</CODE> (<VAR>string</VAR>) and an integer 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 NULL. +</DL> + +</P> + + +<H2><A NAME="SEC18" HREF="history_toc.html#TOC18">History Programming Example</A></H2> + +<P> +The following program demonstrates simple use of the GNU History Library. + +</P> + +<PRE> +main () +{ + 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 && *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, &expansion); + if (result) + fprintf (stderr, "%s\n", expansion); + + if (result < 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]->line); + } + else if (strncmp (line, "delete", 6) == 0) + { + int which; + if ((sscanf (line + 6, "%d", &which)) == 1) + { + HIST_ENTRY *entry = remove_history (which); + if (!entry) + fprintf (stderr, "No such entry %d\n", which); + else + { + free (entry->line); + free (entry); + } + } + else + { + fprintf (stderr, "non-numeric arg given to `delete'\n"); + } + } + } +} +</PRE> + + + +<H1><A NAME="SEC19" HREF="history_toc.html#TOC19">Concept Index</A></H1> +<P> +<H2>a</H2> +<DIR> +<LI><A HREF="history.html#IDX23">anchored search</A> +</DIR> +<H2>e</H2> +<DIR> +<LI><A HREF="history.html#IDX2">event designators</A> +</DIR> +<H2>h</H2> +<DIR> +<LI><A HREF="history.html#IDX3">history events</A> +<LI><A HREF="history.html#IDX1">history expansion</A> +<LI><A HREF="history.html#IDX22">History Searching</A> +</DIR> + +</P> + + +<H1><A NAME="SEC20" HREF="history_toc.html#TOC20">Function and Variable Index</A></H1> +<P> +<H2>a</H2> +<DIR> +<LI><A HREF="history.html#IDX7">add_history</A> +<LI><A HREF="history.html#IDX30">append_history</A> +</DIR> +<H2>c</H2> +<DIR> +<LI><A HREF="history.html#IDX10">clear_history</A> +<LI><A HREF="history.html#IDX16">current_history</A> +</DIR> +<H2>g</H2> +<DIR> +<LI><A HREF="history.html#IDX34">get_history_event</A> +</DIR> +<H2>h</H2> +<DIR> +<LI><A HREF="history.html#IDX33">history_arg_extract</A> +<LI><A HREF="history.html#IDX36">history_base</A> +<LI><A HREF="history.html#IDX41">history_comment_char</A> +<LI><A HREF="history.html#IDX32">history_expand</A> +<LI><A HREF="history.html#IDX39">history_expansion_char</A> +<LI><A HREF="history.html#IDX17">history_get</A> +<LI><A HREF="history.html#IDX5">history_get_history_state</A> +<LI><A HREF="history.html#IDX45">history_inhibit_expansion_function</A> +<LI><A HREF="history.html#IDX13">history_is_stifled</A> +<LI><A HREF="history.html#IDX37">history_length</A> +<LI><A HREF="history.html#IDX14">history_list</A> +<LI><A HREF="history.html#IDX42">history_no_expand_chars</A> +<LI><A HREF="history.html#IDX44">history_quotes_inhibit_expansion</A> +<LI><A HREF="history.html#IDX24">history_search</A> +<LI><A HREF="history.html#IDX43">history_search_delimiter_chars</A> +<LI><A HREF="history.html#IDX26">history_search_pos</A> +<LI><A HREF="history.html#IDX25">history_search_prefix</A> +<LI><A HREF="history.html#IDX6">history_set_history_state</A> +<LI><A HREF="history.html#IDX19">history_set_pos</A> +<LI><A HREF="history.html#IDX40">history_subst_char</A> +<LI><A HREF="history.html#IDX35">history_tokenize</A> +<LI><A HREF="history.html#IDX18">history_total_bytes</A> +<LI><A HREF="history.html#IDX31">history_truncate_file</A> +</DIR> +<H2>m</H2> +<DIR> +<LI><A HREF="history.html#IDX38">max_input_history</A> +</DIR> +<H2>n</H2> +<DIR> +<LI><A HREF="history.html#IDX21">next_history</A> +</DIR> +<H2>p</H2> +<DIR> +<LI><A HREF="history.html#IDX20">previous_history</A> +</DIR> +<H2>r</H2> +<DIR> +<LI><A HREF="history.html#IDX27">read_history</A> +<LI><A HREF="history.html#IDX28">read_history_range</A> +<LI><A HREF="history.html#IDX8">remove_history</A> +<LI><A HREF="history.html#IDX9">replace_history_entry</A> +</DIR> +<H2>s</H2> +<DIR> +<LI><A HREF="history.html#IDX11">stifle_history</A> +</DIR> +<H2>u</H2> +<DIR> +<LI><A HREF="history.html#IDX12">unstifle_history</A> +<LI><A HREF="history.html#IDX4">using_history</A> +</DIR> +<H2>w</H2> +<DIR> +<LI><A HREF="history.html#IDX15">where_history</A> +<LI><A HREF="history.html#IDX29">write_history</A> +</DIR> + +</P> +<P><HR><P> +This document was generated on 16 April 1997 using the +<A HREF="http://wwwcn.cern.ch/dci/texi2html/">texi2html</A> +translator version 1.51.</P> +</BODY> +</HTML>