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6 <TITLE>GNU History Library
</TITLE>
9 <H1>GNU History Library
</H1>
10 <H2>Edition
4.1, for
<CODE>History Library
</CODE> Version
4.1.
</H2>
12 <ADDRESS>Brian Fox, Free Software Foundation
</ADDRESS>
13 <ADDRESS>Chet Ramey, Case Western Reserve University
</ADDRESS>
16 <H1>Table of Contents
</H1>
18 <LI><A NAME=
"TOC1" HREF=
"history.html#SEC1">Using History Interactively
</A>
20 <LI><A NAME=
"TOC2" HREF=
"history.html#SEC2">History Expansion
</A>
22 <LI><A NAME=
"TOC3" HREF=
"history.html#SEC3">Event Designators
</A>
23 <LI><A NAME=
"TOC4" HREF=
"history.html#SEC4">Word Designators
</A>
24 <LI><A NAME=
"TOC5" HREF=
"history.html#SEC5">Modifiers
</A>
27 <LI><A NAME=
"TOC6" HREF=
"history.html#SEC6">Programming with GNU History
</A>
29 <LI><A NAME=
"TOC7" HREF=
"history.html#SEC7">Introduction to History
</A>
30 <LI><A NAME=
"TOC8" HREF=
"history.html#SEC8">History Storage
</A>
31 <LI><A NAME=
"TOC9" HREF=
"history.html#SEC9">History Functions
</A>
33 <LI><A NAME=
"TOC10" HREF=
"history.html#SEC10">Initializing History and State Management
</A>
34 <LI><A NAME=
"TOC11" HREF=
"history.html#SEC11">History List Management
</A>
35 <LI><A NAME=
"TOC12" HREF=
"history.html#SEC12">Information About the History List
</A>
36 <LI><A NAME=
"TOC13" HREF=
"history.html#SEC13">Moving Around the History List
</A>
37 <LI><A NAME=
"TOC14" HREF=
"history.html#SEC14">Searching the History List
</A>
38 <LI><A NAME=
"TOC15" HREF=
"history.html#SEC15">Managing the History File
</A>
39 <LI><A NAME=
"TOC16" HREF=
"history.html#SEC16">History Expansion
</A>
41 <LI><A NAME=
"TOC17" HREF=
"history.html#SEC17">History Variables
</A>
42 <LI><A NAME=
"TOC18" HREF=
"history.html#SEC18">History Programming Example
</A>
44 <LI><A NAME=
"TOC19" HREF=
"history.html#SEC19">Concept Index
</A>
45 <LI><A NAME=
"TOC20" HREF=
"history.html#SEC20">Function and Variable Index
</A>
50 This document describes the GNU History library, a programming tool that
51 provides a consistent user interface for recalling lines of previously
56 Published by the Free Software Foundation
<BR>
57 59 Temple Place, Suite
330,
<BR>
62 Permission is granted to make and distribute verbatim copies of
63 this manual provided the copyright notice and this permission notice
64 are preserved on all copies.
68 Permission is granted to copy and distribute modified versions of this
69 manual under the conditions for verbatim copying, provided that the entire
70 resulting derived work is distributed under the terms of a permission
71 notice identical to this one.
75 Permission is granted to copy and distribute translations of this manual
76 into another language, under the above conditions for modified versions,
77 except that this permission notice may be stated in a translation approved
78 by the Free Software Foundation.
82 Copyright (C)
1988-
1999 Free Software Foundation, Inc.
88 <H1><A NAME=
"SEC1" HREF=
"history.html#TOC1">Using History Interactively
</A></H1>
91 This chapter describes how to use the GNU History Library interactively,
92 from a user's standpoint. It should be considered a user's guide. For
93 information on using the GNU History Library in your own programs,
94 see section
<A HREF=
"history.html#SEC6">Programming with GNU History
</A>.
99 <LI><A HREF=
"history.html#SEC2">History Interaction
</A>: What it feels like using History as a user.
104 <H2><A NAME=
"SEC2" HREF=
"history.html#TOC2">History Expansion
</A></H2>
110 The History library provides a history expansion feature that is similar
111 to the history expansion provided by
<CODE>csh
</CODE>. This section
112 describes the syntax used to manipulate the history information.
116 History expansions introduce words from the history list into
117 the input stream, making it easy to repeat commands, insert the
118 arguments to a previous command into the current input line, or
119 fix errors in previous commands quickly.
123 History expansion takes place in two parts. The first is to determine
124 which line from the history list should be used during substitution.
125 The second is to select portions of that line for inclusion into the
126 current one. The line selected from the history is called the
127 <EM>event
</EM>, and the portions of that line that are acted upon are
128 called
<EM>words
</EM>. Various
<EM>modifiers
</EM> are available to manipulate
129 the selected words. The line is broken into words in the same fashion
130 that Bash does, so that several words
131 surrounded by quotes are considered one word.
132 History expansions are introduced by the appearance of the
133 history expansion character, which is
<SAMP>`!'
</SAMP> by default.
139 <LI><A HREF=
"history.html#SEC3">Event Designators
</A>: How to specify which history line to use.
140 <LI><A HREF=
"history.html#SEC4">Word Designators
</A>: Specifying which words are of interest.
141 <LI><A HREF=
"history.html#SEC5">Modifiers
</A>: Modifying the results of substitution.
146 <H3><A NAME=
"SEC3" HREF=
"history.html#TOC3">Event Designators
</A></H3>
152 An event designator is a reference to a command line entry in the
161 Start a history substitution, except when followed by a space, tab,
162 the end of the line,
<SAMP>`='
</SAMP> or
<SAMP>`('
</SAMP>.
164 <DT><CODE>!
<VAR>n
</VAR></CODE>
166 Refer to command line
<VAR>n
</VAR>.
168 <DT><CODE>!-
<VAR>n
</VAR></CODE>
170 Refer to the command
<VAR>n
</VAR> lines back.
174 Refer to the previous command. This is a synonym for
<SAMP>`!-
1'
</SAMP>.
176 <DT><CODE>!
<VAR>string
</VAR></CODE>
178 Refer to the most recent command starting with
<VAR>string
</VAR>.
180 <DT><CODE>!?
<VAR>string
</VAR>[?]
</CODE>
182 Refer to the most recent command containing
<VAR>string
</VAR>. The trailing
183 <SAMP>`?'
</SAMP> may be omitted if the
<VAR>string
</VAR> is followed immediately by
186 <DT><CODE>^
<VAR>string1
</VAR>^
<VAR>string2
</VAR>^
</CODE>
188 Quick Substitution. Repeat the last command, replacing
<VAR>string1
</VAR>
189 with
<VAR>string2
</VAR>. Equivalent to
190 <CODE>!!:s/
<VAR>string1
</VAR>/
<VAR>string2
</VAR>/
</CODE>.
194 The entire command line typed so far.
200 <H3><A NAME=
"SEC4" HREF=
"history.html#TOC4">Word Designators
</A></H3>
203 Word designators are used to select desired words from the event.
204 A
<SAMP>`:'
</SAMP> separates the event specification from the word designator. It
205 may be omitted if the word designator begins with a
<SAMP>`^'
</SAMP>,
<SAMP>`$'
</SAMP>,
206 <SAMP>`*'
</SAMP>,
<SAMP>`-'
</SAMP>, or
<SAMP>`%'
</SAMP>. Words are numbered from the beginning
207 of the line, with the first word being denoted by
0 (zero). Words are
208 inserted into the current line separated by single spaces.
219 designates the preceding command. When you type this, the preceding
220 command is repeated in toto.
222 <DT><CODE>!!:$
</CODE>
224 designates the last argument of the preceding command. This may be
225 shortened to
<CODE>!$
</CODE>.
227 <DT><CODE>!fi:
2</CODE>
229 designates the second argument of the most recent command starting with
230 the letters
<CODE>fi
</CODE>.
234 Here are the word designators:
238 <DT><CODE>0 (zero)
</CODE>
240 The
<CODE>0</CODE>th word. For many applications, this is the command word.
242 <DT><CODE><VAR>n
</VAR></CODE>
244 The
<VAR>n
</VAR>th word.
248 The first argument; that is, word
1.
256 The word matched by the most recent
<SAMP>`?
<VAR>string
</VAR>?'
</SAMP> search.
258 <DT><CODE><VAR>x
</VAR>-
<VAR>y
</VAR></CODE>
260 A range of words;
<SAMP>`-
<VAR>y
</VAR>'
</SAMP> abbreviates
<SAMP>`
0-
<VAR>y
</VAR>'
</SAMP>.
264 All of the words, except the
<CODE>0</CODE>th. This is a synonym for
<SAMP>`
1-$'
</SAMP>.
265 It is not an error to use
<SAMP>`*'
</SAMP> if there is just one word in the event;
266 the empty string is returned in that case.
268 <DT><CODE><VAR>x
</VAR>*
</CODE>
270 Abbreviates
<SAMP>`
<VAR>x
</VAR>-$'
</SAMP>
272 <DT><CODE><VAR>x
</VAR>-
</CODE>
274 Abbreviates
<SAMP>`
<VAR>x
</VAR>-$'
</SAMP> like
<SAMP>`
<VAR>x
</VAR>*'
</SAMP>, but omits the last word.
279 If a word designator is supplied without an event specification, the
280 previous command is used as the event.
285 <H3><A NAME=
"SEC5" HREF=
"history.html#TOC5">Modifiers
</A></H3>
288 After the optional word designator, you can add a sequence of one or more
289 of the following modifiers, each preceded by a
<SAMP>`:'
</SAMP>.
296 Remove a trailing pathname component, leaving only the head.
300 Remove all leading pathname components, leaving the tail.
304 Remove a trailing suffix of the form
<SAMP>`.
<VAR>suffix
</VAR>'
</SAMP>, leaving
309 Remove all but the trailing suffix.
313 Print the new command but do not execute it.
315 <DT><CODE>s/
<VAR>old
</VAR>/
<VAR>new
</VAR>/
</CODE>
317 Substitute
<VAR>new
</VAR> for the first occurrence of
<VAR>old
</VAR> in the
318 event line. Any delimiter may be used in place of
<SAMP>`/'
</SAMP>.
319 The delimiter may be quoted in
<VAR>old
</VAR> and
<VAR>new
</VAR>
320 with a single backslash. If
<SAMP>`
&'
</SAMP> appears in
<VAR>new
</VAR>,
321 it is replaced by
<VAR>old
</VAR>. A single backslash will quote
322 the
<SAMP>`
&'
</SAMP>. The final delimiter is optional if it is the last
323 character on the input line.
325 <DT><CODE>&</CODE>
327 Repeat the previous substitution.
331 Cause changes to be applied over the entire event line. Used in
332 conjunction with
<SAMP>`s'
</SAMP>, as in
<CODE>gs/
<VAR>old
</VAR>/
<VAR>new
</VAR>/
</CODE>,
333 or with
<SAMP>`
&'
</SAMP>.
339 <H1><A NAME=
"SEC6" HREF=
"history.html#TOC6">Programming with GNU History
</A></H1>
342 This chapter describes how to interface programs that you write
343 with the GNU History Library.
344 It should be considered a technical guide.
345 For information on the interactive use of GNU History, see section
<A HREF=
"history.html#SEC1">Using History Interactively
</A>.
350 <LI><A HREF=
"history.html#SEC7">Introduction to History
</A>: What is the GNU History library for?
351 <LI><A HREF=
"history.html#SEC8">History Storage
</A>: How information is stored.
352 <LI><A HREF=
"history.html#SEC9">History Functions
</A>: Functions that you can use.
353 <LI><A HREF=
"history.html#SEC17">History Variables
</A>: Variables that control behaviour.
354 <LI><A HREF=
"history.html#SEC18">History Programming Example
</A>: Example of using the GNU History Library.
359 <H2><A NAME=
"SEC7" HREF=
"history.html#TOC7">Introduction to History
</A></H2>
362 Many programs read input from the user a line at a time. The GNU History
363 library is able to keep track of those lines, associate arbitrary data with
364 each line, and utilize information from previous lines in composing new
369 The programmer using the History library has available functions
370 for remembering lines on a history list, associating arbitrary data
371 with a line, removing lines from the list, searching through the list
372 for a line containing an arbitrary text string, and referencing any line
373 in the list directly. In addition, a history
<EM>expansion
</EM> function
374 is available which provides for a consistent user interface across
379 The user using programs written with the History library has the
380 benefit of a consistent user interface with a set of well-known
381 commands for manipulating the text of previous lines and using that text
382 in new commands. The basic history manipulation commands are similar to
383 the history substitution provided by
<CODE>csh
</CODE>.
387 If the programmer desires, he can use the Readline library, which
388 includes some history manipulation by default, and has the added
389 advantage of command line editing.
393 Before declaring any functions using any functionality the History
394 library provides in other code, an application writer should include
395 the file
<CODE><readline/history.h
></CODE> in any file that uses the
396 History library's features. It supplies extern declarations for all
397 of the library's public functions and variables, and declares all of
398 the public data structures.
403 <H2><A NAME=
"SEC8" HREF=
"history.html#TOC8">History Storage
</A></H2>
406 The history list is an array of history entries. A history entry is
412 typedef struct _hist_entry {
419 The history list itself might therefore be declared as
424 HIST_ENTRY **the_history_list;
428 The state of the History library is encapsulated into a single structure:
433 /* A structure used to pass the current state of the history stuff around. */
434 typedef struct _hist_state {
435 HIST_ENTRY **entries; /* Pointer to the entries themselves. */
436 int offset; /* The location pointer within this array. */
437 int length; /* Number of elements within this array. */
438 int size; /* Number of slots allocated to this array. */
444 If the flags member includes
<CODE>HS_STIFLED
</CODE>, the history has been
450 <H2><A NAME=
"SEC9" HREF=
"history.html#TOC9">History Functions
</A></H2>
453 This section describes the calling sequence for the various functions
454 present in GNU History.
459 <LI><A HREF=
"history.html#SEC10">Initializing History and State Management
</A>: Functions to call when you
460 want to use history in a
462 <LI><A HREF=
"history.html#SEC11">History List Management
</A>: Functions used to manage the list
464 <LI><A HREF=
"history.html#SEC12">Information About the History List
</A>: Functions returning information about
466 <LI><A HREF=
"history.html#SEC13">Moving Around the History List
</A>: Functions used to change the position
468 <LI><A HREF=
"history.html#SEC14">Searching the History List
</A>: Functions to search the history list
469 for entries containing a string.
470 <LI><A HREF=
"history.html#SEC15">Managing the History File
</A>: Functions that read and write a file
471 containing the history list.
472 <LI><A HREF=
"history.html#SEC16">History Expansion
</A>: Functions to perform csh-like history
478 <H3><A NAME=
"SEC10" HREF=
"history.html#TOC10">Initializing History and State Management
</A></H3>
481 This section describes functions used to initialize and manage
482 the state of the History library when you want to use the history
483 functions in your program.
488 <DT><U>Function:
</U> void
<B>using_history
</B> <I>()
</I>
489 <DD><A NAME=
"IDX4"></A>
490 Begin a session in which the history functions might be used. This
491 initializes the interactive variables.
497 <DT><U>Function:
</U> HISTORY_STATE *
<B>history_get_history_state
</B> <I>()
</I>
498 <DD><A NAME=
"IDX5"></A>
499 Return a structure describing the current state of the input history.
505 <DT><U>Function:
</U> void
<B>history_set_history_state
</B> <I>(HISTORY_STATE *state)
</I>
506 <DD><A NAME=
"IDX6"></A>
507 Set the state of the history list according to
<VAR>state
</VAR>.
513 <H3><A NAME=
"SEC11" HREF=
"history.html#TOC11">History List Management
</A></H3>
516 These functions manage individual entries on the history list, or set
517 parameters managing the list itself.
522 <DT><U>Function:
</U> void
<B>add_history
</B> <I>(char *string)
</I>
523 <DD><A NAME=
"IDX7"></A>
524 Place
<VAR>string
</VAR> at the end of the history list. The associated data
525 field (if any) is set to
<CODE>NULL
</CODE>.
531 <DT><U>Function:
</U> HIST_ENTRY *
<B>remove_history
</B> <I>(int which)
</I>
532 <DD><A NAME=
"IDX8"></A>
533 Remove history entry at offset
<VAR>which
</VAR> from the history. The
534 removed element is returned so you can free the line, data,
535 and containing structure.
541 <DT><U>Function:
</U> HIST_ENTRY *
<B>replace_history_entry
</B> <I>(int which, char *line, char *data)
</I>
542 <DD><A NAME=
"IDX9"></A>
543 Make the history entry at offset
<VAR>which
</VAR> have
<VAR>line
</VAR> and
<VAR>data
</VAR>.
544 This returns the old entry so you can dispose of the data. In the case
545 of an invalid
<VAR>which
</VAR>, a
<CODE>NULL
</CODE> pointer is returned.
551 <DT><U>Function:
</U> void
<B>clear_history
</B> <I>()
</I>
552 <DD><A NAME=
"IDX10"></A>
553 Clear the history list by deleting all the entries.
559 <DT><U>Function:
</U> void
<B>stifle_history
</B> <I>(int max)
</I>
560 <DD><A NAME=
"IDX11"></A>
561 Stifle the history list, remembering only the last
<VAR>max
</VAR> entries.
567 <DT><U>Function:
</U> int
<B>unstifle_history
</B> <I>()
</I>
568 <DD><A NAME=
"IDX12"></A>
569 Stop stifling the history. This returns the previous amount the
570 history was stifled. The value is positive if the history was
571 stifled, negative if it wasn't.
577 <DT><U>Function:
</U> int
<B>history_is_stifled
</B> <I>()
</I>
578 <DD><A NAME=
"IDX13"></A>
579 Returns non-zero if the history is stifled, zero if it is not.
585 <H3><A NAME=
"SEC12" HREF=
"history.html#TOC12">Information About the History List
</A></H3>
588 These functions return information about the entire history list or
589 individual list entries.
594 <DT><U>Function:
</U> HIST_ENTRY **
<B>history_list
</B> <I>()
</I>
595 <DD><A NAME=
"IDX14"></A>
596 Return a
<CODE>NULL
</CODE> terminated array of
<CODE>HIST_ENTRY
</CODE> which is the
597 current input history. Element
0 of this list is the beginning of time.
598 If there is no history, return
<CODE>NULL
</CODE>.
604 <DT><U>Function:
</U> int
<B>where_history
</B> <I>()
</I>
605 <DD><A NAME=
"IDX15"></A>
606 Returns the offset of the current history element.
612 <DT><U>Function:
</U> HIST_ENTRY *
<B>current_history
</B> <I>()
</I>
613 <DD><A NAME=
"IDX16"></A>
614 Return the history entry at the current position, as determined by
615 <CODE>where_history ()
</CODE>. If there is no entry there, return a
<CODE>NULL
</CODE>
622 <DT><U>Function:
</U> HIST_ENTRY *
<B>history_get
</B> <I>(int offset)
</I>
623 <DD><A NAME=
"IDX17"></A>
624 Return the history entry at position
<VAR>offset
</VAR>, starting from
625 <CODE>history_base
</CODE>. If there is no entry there, or if
<VAR>offset
</VAR>
626 is greater than the history length, return a
<CODE>NULL
</CODE> pointer.
632 <DT><U>Function:
</U> int
<B>history_total_bytes
</B> <I>()
</I>
633 <DD><A NAME=
"IDX18"></A>
634 Return the number of bytes that the primary history entries are using.
635 This function returns the sum of the lengths of all the lines in the
642 <H3><A NAME=
"SEC13" HREF=
"history.html#TOC13">Moving Around the History List
</A></H3>
645 These functions allow the current index into the history list to be
651 <DT><U>Function:
</U> int
<B>history_set_pos
</B> <I>(int pos)
</I>
652 <DD><A NAME=
"IDX19"></A>
653 Set the position in the history list to
<VAR>pos
</VAR>, an absolute index
660 <DT><U>Function:
</U> HIST_ENTRY *
<B>previous_history
</B> <I>()
</I>
661 <DD><A NAME=
"IDX20"></A>
662 Back up the current history offset to the previous history entry, and
663 return a pointer to that entry. If there is no previous entry, return
664 a
<CODE>NULL
</CODE> pointer.
670 <DT><U>Function:
</U> HIST_ENTRY *
<B>next_history
</B> <I>()
</I>
671 <DD><A NAME=
"IDX21"></A>
672 Move the current history offset forward to the next history entry, and
673 return the a pointer to that entry. If there is no next entry, return
674 a
<CODE>NULL
</CODE> pointer.
680 <H3><A NAME=
"SEC14" HREF=
"history.html#TOC14">Searching the History List
</A></H3>
686 These functions allow searching of the history list for entries containing
687 a specific string. Searching may be performed both forward and backward
688 from the current history position. The search may be
<EM>anchored
</EM>,
689 meaning that the string must match at the beginning of the history entry.
695 <DT><U>Function:
</U> int
<B>history_search
</B> <I>(char *string, int direction)
</I>
696 <DD><A NAME=
"IDX24"></A>
697 Search the history for
<VAR>string
</VAR>, starting at the current history
698 offset. If
<VAR>direction
</VAR> < 0, then the search is through previous entries,
699 else through subsequent. If
<VAR>string
</VAR> is found, then
700 the current history index is set to that history entry, and the value
701 returned is the offset in the line of the entry where
702 <VAR>string
</VAR> was found. Otherwise, nothing is changed, and a -
1 is
709 <DT><U>Function:
</U> int
<B>history_search_prefix
</B> <I>(char *string, int direction)
</I>
710 <DD><A NAME=
"IDX25"></A>
711 Search the history for
<VAR>string
</VAR>, starting at the current history
712 offset. The search is anchored: matching lines must begin with
713 <VAR>string
</VAR>. If
<VAR>direction
</VAR> < 0, then the search is through previous
714 entries, else through subsequent. If
<VAR>string
</VAR> is found, then the
715 current history index is set to that entry, and the return value is
0.
716 Otherwise, nothing is changed, and a -
1 is returned.
722 <DT><U>Function:
</U> int
<B>history_search_pos
</B> <I>(char *string, int direction, int pos)
</I>
723 <DD><A NAME=
"IDX26"></A>
724 Search for
<VAR>string
</VAR> in the history list, starting at
<VAR>pos
</VAR>, an
725 absolute index into the list. If
<VAR>direction
</VAR> is negative, the search
726 proceeds backward from
<VAR>pos
</VAR>, otherwise forward. Returns the absolute
727 index of the history element where
<VAR>string
</VAR> was found, or -
1 otherwise.
733 <H3><A NAME=
"SEC15" HREF=
"history.html#TOC15">Managing the History File
</A></H3>
736 The History library can read the history from and write it to a file.
737 This section documents the functions for managing a history file.
742 <DT><U>Function:
</U> int
<B>read_history
</B> <I>(char *filename)
</I>
743 <DD><A NAME=
"IDX27"></A>
744 Add the contents of
<VAR>filename
</VAR> to the history list, a line at a
745 time. If
<VAR>filename
</VAR> is
<CODE>NULL
</CODE>, then read from
746 <TT>`~/.history'
</TT>. Returns
0 if successful, or errno if not.
752 <DT><U>Function:
</U> int
<B>read_history_range
</B> <I>(char *filename, int from, int to)
</I>
753 <DD><A NAME=
"IDX28"></A>
754 Read a range of lines from
<VAR>filename
</VAR>, adding them to the history list.
755 Start reading at line
<VAR>from
</VAR> and end at
<VAR>to
</VAR>. If
756 <VAR>from
</VAR> is zero, start at the beginning. If
<VAR>to
</VAR> is less than
757 <VAR>from
</VAR>, then read until the end of the file. If
<VAR>filename
</VAR> is
758 <CODE>NULL
</CODE>, then read from
<TT>`~/.history'
</TT>. Returns
0 if successful,
759 or
<CODE>errno
</CODE> if not.
765 <DT><U>Function:
</U> int
<B>write_history
</B> <I>(char *filename)
</I>
766 <DD><A NAME=
"IDX29"></A>
767 Write the current history to
<VAR>filename
</VAR>, overwriting
<VAR>filename
</VAR>
768 if necessary. If
<VAR>filename
</VAR> is
769 <CODE>NULL
</CODE>, then write the history list to
<TT>`~/.history'
</TT>. Values
770 returned are as in
<CODE>read_history ()
</CODE>.
776 <DT><U>Function:
</U> int
<B>append_history
</B> <I>(int nelements, char *filename)
</I>
777 <DD><A NAME=
"IDX30"></A>
778 Append the last
<VAR>nelements
</VAR> of the history list to
<VAR>filename
</VAR>.
784 <DT><U>Function:
</U> int
<B>history_truncate_file
</B> <I>(char *filename, int nlines)
</I>
785 <DD><A NAME=
"IDX31"></A>
786 Truncate the history file
<VAR>filename
</VAR>, leaving only the last
787 <VAR>nlines
</VAR> lines.
793 <H3><A NAME=
"SEC16" HREF=
"history.html#TOC16">History Expansion
</A></H3>
796 These functions implement
<CODE>csh
</CODE>-like history expansion.
801 <DT><U>Function:
</U> int
<B>history_expand
</B> <I>(char *string, char **output)
</I>
802 <DD><A NAME=
"IDX32"></A>
803 Expand
<VAR>string
</VAR>, placing the result into
<VAR>output
</VAR>, a pointer
804 to a string (see section
<A HREF=
"history.html#SEC2">History Expansion
</A>). Returns:
809 If no expansions took place (or, if the only change in
810 the text was the de-slashifying of the history expansion
814 if expansions did take place;
817 if there was an error in expansion;
820 if the returned line should be displayed, but not executed,
821 as with the
<CODE>:p
</CODE> modifier (see section
<A HREF=
"history.html#SEC5">Modifiers
</A>).
825 If an error ocurred in expansion, then
<VAR>output
</VAR> contains a descriptive
832 <DT><U>Function:
</U> char *
<B>history_arg_extract
</B> <I>(int first, int last, char *string)
</I>
833 <DD><A NAME=
"IDX33"></A>
834 Extract a string segment consisting of the
<VAR>first
</VAR> through
<VAR>last
</VAR>
835 arguments present in
<VAR>string
</VAR>. Arguments are broken up as in Bash.
841 <DT><U>Function:
</U> char *
<B>get_history_event
</B> <I>(char *string, int *cindex, int qchar)
</I>
842 <DD><A NAME=
"IDX34"></A>
843 Returns the text of the history event beginning at
<VAR>string
</VAR> +
844 <VAR>*cindex
</VAR>.
<VAR>*cindex
</VAR> is modified to point to after the event
845 specifier. At function entry,
<VAR>cindex
</VAR> points to the index into
846 <VAR>string
</VAR> where the history event specification begins.
<VAR>qchar
</VAR>
847 is a character that is allowed to end the event specification in addition
848 to the
"normal" terminating characters.
854 <DT><U>Function:
</U> char **
<B>history_tokenize
</B> <I>(char *string)
</I>
855 <DD><A NAME=
"IDX35"></A>
856 Return an array of tokens parsed out of
<VAR>string
</VAR>, much as the
857 shell might. The tokens are split on white space and on the
858 characters
<CODE>()
<>;
&|$
</CODE>, and shell quoting conventions are
865 <H2><A NAME=
"SEC17" HREF=
"history.html#TOC17">History Variables
</A></H2>
868 This section describes the externally visible variables exported by
869 the GNU History Library.
874 <DT><U>Variable:
</U> int
<B>history_base
</B>
875 <DD><A NAME=
"IDX36"></A>
876 The logical offset of the first entry in the history list.
882 <DT><U>Variable:
</U> int
<B>history_length
</B>
883 <DD><A NAME=
"IDX37"></A>
884 The number of entries currently stored in the history list.
890 <DT><U>Variable:
</U> int
<B>max_input_history
</B>
891 <DD><A NAME=
"IDX38"></A>
892 The maximum number of history entries. This must be changed using
893 <CODE>stifle_history ()
</CODE>.
899 <DT><U>Variable:
</U> char
<B>history_expansion_char
</B>
900 <DD><A NAME=
"IDX39"></A>
901 The character that starts a history event. The default is
<SAMP>`!'
</SAMP>.
907 <DT><U>Variable:
</U> char
<B>history_subst_char
</B>
908 <DD><A NAME=
"IDX40"></A>
909 The character that invokes word substitution if found at the start of
910 a line. The default is
<SAMP>`^'
</SAMP>.
916 <DT><U>Variable:
</U> char
<B>history_comment_char
</B>
917 <DD><A NAME=
"IDX41"></A>
918 During tokenization, if this character is seen as the first character
919 of a word, then it and all subsequent characters up to a newline are
920 ignored, suppressing history expansion for the remainder of the line.
921 This is disabled by default.
927 <DT><U>Variable:
</U> char *
<B>history_no_expand_chars
</B>
928 <DD><A NAME=
"IDX42"></A>
929 The list of characters which inhibit history expansion if found immediately
930 following
<VAR>history_expansion_char
</VAR>. The default is whitespace and
937 <DT><U>Variable:
</U> char *
<B>history_search_delimiter_chars
</B>
938 <DD><A NAME=
"IDX43"></A>
939 The list of additional characters which can delimit a history search
940 string, in addition to whitespace,
<SAMP>`:'
</SAMP> and
<SAMP>`?'
</SAMP> in the case of
941 a substring search. The default is empty.
947 <DT><U>Variable:
</U> int
<B>history_quotes_inhibit_expansion
</B>
948 <DD><A NAME=
"IDX44"></A>
949 If non-zero, single-quoted words are not scanned for the history expansion
950 character. The default value is
0.
956 <DT><U>Variable:
</U> Function *
<B>history_inhibit_expansion_function
</B>
957 <DD><A NAME=
"IDX45"></A>
958 This should be set to the address of a function that takes two arguments:
959 a
<CODE>char *
</CODE> (
<VAR>string
</VAR>) and an integer index into that string (
<VAR>i
</VAR>).
960 It should return a non-zero value if the history expansion starting at
961 <VAR>string[i]
</VAR> should not be performed; zero if the expansion should
963 It is intended for use by applications like Bash that use the history
964 expansion character for additional purposes.
965 By default, this variable is set to NULL.
971 <H2><A NAME=
"SEC18" HREF=
"history.html#TOC18">History Programming Example
</A></H2>
974 The following program demonstrates simple use of the GNU History Library.
989 printf (
"history$ ");
991 t = fgets (line, sizeof (line) -
1, stdin);
995 if (t[len -
1] == '\n')
1000 strcpy (line,
"quit");
1007 result = history_expand (line,
&expansion);
1009 fprintf (stderr,
"%s\n", expansion);
1011 if (result
< 0 || result ==
2)
1017 add_history (expansion);
1018 strncpy (line, expansion, sizeof (line) -
1);
1022 if (strcmp (line,
"quit") ==
0)
1024 else if (strcmp (line,
"save") ==
0)
1025 write_history (
"history_file");
1026 else if (strcmp (line,
"read") ==
0)
1027 read_history (
"history_file");
1028 else if (strcmp (line,
"list") ==
0)
1030 register HIST_ENTRY **the_list;
1033 the_list = history_list ();
1035 for (i =
0; the_list[i]; i++)
1036 printf (
"%d: %s\n", i + history_base, the_list[i]-
>line);
1038 else if (strncmp (line,
"delete",
6) ==
0)
1041 if ((sscanf (line +
6,
"%d",
&which)) ==
1)
1043 HIST_ENTRY *entry = remove_history (which);
1045 fprintf (stderr,
"No such entry %d\n", which);
1048 free (entry-
>line);
1054 fprintf (stderr,
"non-numeric arg given to `delete'\n");
1063 <H1><A NAME=
"SEC19" HREF=
"history.html#TOC19">Concept Index
</A></H1>
1066 <A HREF=
"#cindex_a">a
</A>
1068 <A HREF=
"#cindex_e">e
</A>
1070 <A HREF=
"#cindex_h">h
</A>
1072 <H2><A NAME=
"cindex_a">a
</A></H2>
1074 <LI><A HREF=
"history.html#IDX23">anchored search
</A>
1076 <H2><A NAME=
"cindex_e">e
</A></H2>
1078 <LI><A HREF=
"history.html#IDX2">event designators
</A>
1080 <H2><A NAME=
"cindex_h">h
</A></H2>
1082 <LI><A HREF=
"history.html#IDX3">history events
</A>
1083 <LI><A HREF=
"history.html#IDX1">history expansion
</A>
1084 <LI><A HREF=
"history.html#IDX22">History Searching
</A>
1090 <H1><A NAME=
"SEC20" HREF=
"history.html#TOC20">Function and Variable Index
</A></H1>
1093 <A HREF=
"#vindex_a">a
</A>
1095 <A HREF=
"#vindex_c">c
</A>
1097 <A HREF=
"#vindex_g">g
</A>
1099 <A HREF=
"#vindex_h">h
</A>
1101 <A HREF=
"#vindex_m">m
</A>
1103 <A HREF=
"#vindex_n">n
</A>
1105 <A HREF=
"#vindex_p">p
</A>
1107 <A HREF=
"#vindex_r">r
</A>
1109 <A HREF=
"#vindex_s">s
</A>
1111 <A HREF=
"#vindex_u">u
</A>
1113 <A HREF=
"#vindex_w">w
</A>
1115 <H2><A NAME=
"vindex_a">a
</A></H2>
1117 <LI><A HREF=
"history.html#IDX7">add_history
</A>
1118 <LI><A HREF=
"history.html#IDX30">append_history
</A>
1120 <H2><A NAME=
"vindex_c">c
</A></H2>
1122 <LI><A HREF=
"history.html#IDX10">clear_history
</A>
1123 <LI><A HREF=
"history.html#IDX16">current_history
</A>
1125 <H2><A NAME=
"vindex_g">g
</A></H2>
1127 <LI><A HREF=
"history.html#IDX34">get_history_event
</A>
1129 <H2><A NAME=
"vindex_h">h
</A></H2>
1131 <LI><A HREF=
"history.html#IDX33">history_arg_extract
</A>
1132 <LI><A HREF=
"history.html#IDX36">history_base
</A>
1133 <LI><A HREF=
"history.html#IDX41">history_comment_char
</A>
1134 <LI><A HREF=
"history.html#IDX32">history_expand
</A>
1135 <LI><A HREF=
"history.html#IDX39">history_expansion_char
</A>
1136 <LI><A HREF=
"history.html#IDX17">history_get
</A>
1137 <LI><A HREF=
"history.html#IDX5">history_get_history_state
</A>
1138 <LI><A HREF=
"history.html#IDX45">history_inhibit_expansion_function
</A>
1139 <LI><A HREF=
"history.html#IDX13">history_is_stifled
</A>
1140 <LI><A HREF=
"history.html#IDX37">history_length
</A>
1141 <LI><A HREF=
"history.html#IDX14">history_list
</A>
1142 <LI><A HREF=
"history.html#IDX42">history_no_expand_chars
</A>
1143 <LI><A HREF=
"history.html#IDX44">history_quotes_inhibit_expansion
</A>
1144 <LI><A HREF=
"history.html#IDX24">history_search
</A>
1145 <LI><A HREF=
"history.html#IDX43">history_search_delimiter_chars
</A>
1146 <LI><A HREF=
"history.html#IDX26">history_search_pos
</A>
1147 <LI><A HREF=
"history.html#IDX25">history_search_prefix
</A>
1148 <LI><A HREF=
"history.html#IDX6">history_set_history_state
</A>
1149 <LI><A HREF=
"history.html#IDX19">history_set_pos
</A>
1150 <LI><A HREF=
"history.html#IDX40">history_subst_char
</A>
1151 <LI><A HREF=
"history.html#IDX35">history_tokenize
</A>
1152 <LI><A HREF=
"history.html#IDX18">history_total_bytes
</A>
1153 <LI><A HREF=
"history.html#IDX31">history_truncate_file
</A>
1155 <H2><A NAME=
"vindex_m">m
</A></H2>
1157 <LI><A HREF=
"history.html#IDX38">max_input_history
</A>
1159 <H2><A NAME=
"vindex_n">n
</A></H2>
1161 <LI><A HREF=
"history.html#IDX21">next_history
</A>
1163 <H2><A NAME=
"vindex_p">p
</A></H2>
1165 <LI><A HREF=
"history.html#IDX20">previous_history
</A>
1167 <H2><A NAME=
"vindex_r">r
</A></H2>
1169 <LI><A HREF=
"history.html#IDX27">read_history
</A>
1170 <LI><A HREF=
"history.html#IDX28">read_history_range
</A>
1171 <LI><A HREF=
"history.html#IDX8">remove_history
</A>
1172 <LI><A HREF=
"history.html#IDX9">replace_history_entry
</A>
1174 <H2><A NAME=
"vindex_s">s
</A></H2>
1176 <LI><A HREF=
"history.html#IDX11">stifle_history
</A>
1178 <H2><A NAME=
"vindex_u">u
</A></H2>
1180 <LI><A HREF=
"history.html#IDX12">unstifle_history
</A>
1181 <LI><A HREF=
"history.html#IDX4">using_history
</A>
1183 <H2><A NAME=
"vindex_w">w
</A></H2>
1185 <LI><A HREF=
"history.html#IDX15">where_history
</A>
1186 <LI><A HREF=
"history.html#IDX29">write_history
</A>
1191 This document was generated on
19 January
2000 using the
1192 <A HREF=
"http://wwwinfo.cern.ch/dis/texi2html/">texi2html
</A>
1193 translator version
1.52.
</P>