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6 <TITLE>GNU History Library
</TITLE>
9 <H1>GNU History Library
</H1>
10 <H2>Edition
4.0, for
<CODE>History Library
</CODE> Version
4.0.
</H2>
11 <H2>December
1998</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>
57 675 Massachusetts Avenue,
<BR>
58 Cambridge, MA
02139 USA
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>`$'
</SAMP>,
206 <SAMP>`*'
</SAMP>,
<SAMP>`-'
</SAMP>, or
<SAMP>`%'
</SAMP>. Words are numbered from the beginning
207 of the line, with the first word being denoted by
0 (zero). Words are
208 inserted into the current line separated by single spaces.
213 <DT><CODE>0 (zero)
</CODE>
215 The
<CODE>0</CODE>th word. For many applications, this is the command word.
217 <DT><CODE><VAR>n
</VAR></CODE>
219 The
<VAR>n
</VAR>th word.
223 The first argument; that is, word
1.
231 The word matched by the most recent
<SAMP>`?
<VAR>string
</VAR>?'
</SAMP> search.
233 <DT><CODE><VAR>x
</VAR>-
<VAR>y
</VAR></CODE>
235 A range of words;
<SAMP>`-
<VAR>y
</VAR>'
</SAMP> abbreviates
<SAMP>`
0-
<VAR>y
</VAR>'
</SAMP>.
239 All of the words, except the
<CODE>0</CODE>th. This is a synonym for
<SAMP>`
1-$'
</SAMP>.
240 It is not an error to use
<SAMP>`*'
</SAMP> if there is just one word in the event;
241 the empty string is returned in that case.
243 <DT><CODE><VAR>x
</VAR>*
</CODE>
245 Abbreviates
<SAMP>`
<VAR>x
</VAR>-$'
</SAMP>
247 <DT><CODE><VAR>x
</VAR>-
</CODE>
249 Abbreviates
<SAMP>`
<VAR>x
</VAR>-$'
</SAMP> like
<SAMP>`
<VAR>x
</VAR>*'
</SAMP>, but omits the last word.
254 If a word designator is supplied without an event specification, the
255 previous command is used as the event.
260 <H3><A NAME=
"SEC5" HREF=
"history.html#TOC5">Modifiers
</A></H3>
263 After the optional word designator, you can add a sequence of one or more
264 of the following modifiers, each preceded by a
<SAMP>`:'
</SAMP>.
271 Remove a trailing pathname component, leaving only the head.
275 Remove all leading pathname components, leaving the tail.
279 Remove a trailing suffix of the form
<SAMP>`.
<VAR>suffix
</VAR>'
</SAMP>, leaving
284 Remove all but the trailing suffix.
288 Print the new command but do not execute it.
290 <DT><CODE>s/
<VAR>old
</VAR>/
<VAR>new
</VAR>/
</CODE>
292 Substitute
<VAR>new
</VAR> for the first occurrence of
<VAR>old
</VAR> in the
293 event line. Any delimiter may be used in place of
<SAMP>`/'
</SAMP>.
294 The delimiter may be quoted in
<VAR>old
</VAR> and
<VAR>new
</VAR>
295 with a single backslash. If
<SAMP>`
&'
</SAMP> appears in
<VAR>new
</VAR>,
296 it is replaced by
<VAR>old
</VAR>. A single backslash will quote
297 the
<SAMP>`
&'
</SAMP>. The final delimiter is optional if it is the last
298 character on the input line.
300 <DT><CODE>&</CODE>
302 Repeat the previous substitution.
306 Cause changes to be applied over the entire event line. Used in
307 conjunction with
<SAMP>`s'
</SAMP>, as in
<CODE>gs/
<VAR>old
</VAR>/
<VAR>new
</VAR>/
</CODE>,
308 or with
<SAMP>`
&'
</SAMP>.
314 <H1><A NAME=
"SEC6" HREF=
"history.html#TOC6">Programming with GNU History
</A></H1>
317 This chapter describes how to interface programs that you write
318 with the GNU History Library.
319 It should be considered a technical guide.
320 For information on the interactive use of GNU History, see section
<A HREF=
"history.html#SEC1">Using History Interactively
</A>.
325 <LI><A HREF=
"history.html#SEC7">Introduction to History
</A>: What is the GNU History library for?
326 <LI><A HREF=
"history.html#SEC8">History Storage
</A>: How information is stored.
327 <LI><A HREF=
"history.html#SEC9">History Functions
</A>: Functions that you can use.
328 <LI><A HREF=
"history.html#SEC17">History Variables
</A>: Variables that control behaviour.
329 <LI><A HREF=
"history.html#SEC18">History Programming Example
</A>: Example of using the GNU History Library.
334 <H2><A NAME=
"SEC7" HREF=
"history.html#TOC7">Introduction to History
</A></H2>
337 Many programs read input from the user a line at a time. The GNU History
338 library is able to keep track of those lines, associate arbitrary data with
339 each line, and utilize information from previous lines in composing new
344 The programmer using the History library has available functions
345 for remembering lines on a history list, associating arbitrary data
346 with a line, removing lines from the list, searching through the list
347 for a line containing an arbitrary text string, and referencing any line
348 in the list directly. In addition, a history
<EM>expansion
</EM> function
349 is available which provides for a consistent user interface across
354 The user using programs written with the History library has the
355 benefit of a consistent user interface with a set of well-known
356 commands for manipulating the text of previous lines and using that text
357 in new commands. The basic history manipulation commands are similar to
358 the history substitution provided by
<CODE>csh
</CODE>.
362 If the programmer desires, he can use the Readline library, which
363 includes some history manipulation by default, and has the added
364 advantage of command line editing.
369 <H2><A NAME=
"SEC8" HREF=
"history.html#TOC8">History Storage
</A></H2>
372 The history list is an array of history entries. A history entry is
378 typedef struct _hist_entry {
385 The history list itself might therefore be declared as
390 HIST_ENTRY **the_history_list;
394 The state of the History library is encapsulated into a single structure:
399 /* A structure used to pass the current state of the history stuff around. */
400 typedef struct _hist_state {
401 HIST_ENTRY **entries; /* Pointer to the entries themselves. */
402 int offset; /* The location pointer within this array. */
403 int length; /* Number of elements within this array. */
404 int size; /* Number of slots allocated to this array. */
410 If the flags member includes
<CODE>HS_STIFLED
</CODE>, the history has been
416 <H2><A NAME=
"SEC9" HREF=
"history.html#TOC9">History Functions
</A></H2>
419 This section describes the calling sequence for the various functions
420 present in GNU History.
425 <LI><A HREF=
"history.html#SEC10">Initializing History and State Management
</A>: Functions to call when you
426 want to use history in a
428 <LI><A HREF=
"history.html#SEC11">History List Management
</A>: Functions used to manage the list
430 <LI><A HREF=
"history.html#SEC12">Information About the History List
</A>: Functions returning information about
432 <LI><A HREF=
"history.html#SEC13">Moving Around the History List
</A>: Functions used to change the position
434 <LI><A HREF=
"history.html#SEC14">Searching the History List
</A>: Functions to search the history list
435 for entries containing a string.
436 <LI><A HREF=
"history.html#SEC15">Managing the History File
</A>: Functions that read and write a file
437 containing the history list.
438 <LI><A HREF=
"history.html#SEC16">History Expansion
</A>: Functions to perform csh-like history
444 <H3><A NAME=
"SEC10" HREF=
"history.html#TOC10">Initializing History and State Management
</A></H3>
447 This section describes functions used to initialize and manage
448 the state of the History library when you want to use the history
449 functions in your program.
454 <DT><U>Function:
</U> void
<B>using_history
</B> <I>()
</I>
455 <DD><A NAME=
"IDX4"></A>
456 Begin a session in which the history functions might be used. This
457 initializes the interactive variables.
463 <DT><U>Function:
</U> HISTORY_STATE *
<B>history_get_history_state
</B> <I>()
</I>
464 <DD><A NAME=
"IDX5"></A>
465 Return a structure describing the current state of the input history.
471 <DT><U>Function:
</U> void
<B>history_set_history_state
</B> <I>(HISTORY_STATE *state)
</I>
472 <DD><A NAME=
"IDX6"></A>
473 Set the state of the history list according to
<VAR>state
</VAR>.
479 <H3><A NAME=
"SEC11" HREF=
"history.html#TOC11">History List Management
</A></H3>
482 These functions manage individual entries on the history list, or set
483 parameters managing the list itself.
488 <DT><U>Function:
</U> void
<B>add_history
</B> <I>(char *string)
</I>
489 <DD><A NAME=
"IDX7"></A>
490 Place
<VAR>string
</VAR> at the end of the history list. The associated data
491 field (if any) is set to
<CODE>NULL
</CODE>.
497 <DT><U>Function:
</U> HIST_ENTRY *
<B>remove_history
</B> <I>(int which)
</I>
498 <DD><A NAME=
"IDX8"></A>
499 Remove history entry at offset
<VAR>which
</VAR> from the history. The
500 removed element is returned so you can free the line, data,
501 and containing structure.
507 <DT><U>Function:
</U> HIST_ENTRY *
<B>replace_history_entry
</B> <I>(int which, char *line, char *data)
</I>
508 <DD><A NAME=
"IDX9"></A>
509 Make the history entry at offset
<VAR>which
</VAR> have
<VAR>line
</VAR> and
<VAR>data
</VAR>.
510 This returns the old entry so you can dispose of the data. In the case
511 of an invalid
<VAR>which
</VAR>, a
<CODE>NULL
</CODE> pointer is returned.
517 <DT><U>Function:
</U> void
<B>clear_history
</B> <I>()
</I>
518 <DD><A NAME=
"IDX10"></A>
519 Clear the history list by deleting all the entries.
525 <DT><U>Function:
</U> void
<B>stifle_history
</B> <I>(int max)
</I>
526 <DD><A NAME=
"IDX11"></A>
527 Stifle the history list, remembering only the last
<VAR>max
</VAR> entries.
533 <DT><U>Function:
</U> int
<B>unstifle_history
</B> <I>()
</I>
534 <DD><A NAME=
"IDX12"></A>
535 Stop stifling the history. This returns the previous amount the
536 history was stifled. The value is positive if the history was
537 stifled, negative if it wasn't.
543 <DT><U>Function:
</U> int
<B>history_is_stifled
</B> <I>()
</I>
544 <DD><A NAME=
"IDX13"></A>
545 Returns non-zero if the history is stifled, zero if it is not.
551 <H3><A NAME=
"SEC12" HREF=
"history.html#TOC12">Information About the History List
</A></H3>
554 These functions return information about the entire history list or
555 individual list entries.
560 <DT><U>Function:
</U> HIST_ENTRY **
<B>history_list
</B> <I>()
</I>
561 <DD><A NAME=
"IDX14"></A>
562 Return a
<CODE>NULL
</CODE> terminated array of
<CODE>HIST_ENTRY
</CODE> which is the
563 current input history. Element
0 of this list is the beginning of time.
564 If there is no history, return
<CODE>NULL
</CODE>.
570 <DT><U>Function:
</U> int
<B>where_history
</B> <I>()
</I>
571 <DD><A NAME=
"IDX15"></A>
572 Returns the offset of the current history element.
578 <DT><U>Function:
</U> HIST_ENTRY *
<B>current_history
</B> <I>()
</I>
579 <DD><A NAME=
"IDX16"></A>
580 Return the history entry at the current position, as determined by
581 <CODE>where_history ()
</CODE>. If there is no entry there, return a
<CODE>NULL
</CODE>
588 <DT><U>Function:
</U> HIST_ENTRY *
<B>history_get
</B> <I>(int offset)
</I>
589 <DD><A NAME=
"IDX17"></A>
590 Return the history entry at position
<VAR>offset
</VAR>, starting from
591 <CODE>history_base
</CODE>. If there is no entry there, or if
<VAR>offset
</VAR>
592 is greater than the history length, return a
<CODE>NULL
</CODE> pointer.
598 <DT><U>Function:
</U> int
<B>history_total_bytes
</B> <I>()
</I>
599 <DD><A NAME=
"IDX18"></A>
600 Return the number of bytes that the primary history entries are using.
601 This function returns the sum of the lengths of all the lines in the
608 <H3><A NAME=
"SEC13" HREF=
"history.html#TOC13">Moving Around the History List
</A></H3>
611 These functions allow the current index into the history list to be
617 <DT><U>Function:
</U> int
<B>history_set_pos
</B> <I>(int pos)
</I>
618 <DD><A NAME=
"IDX19"></A>
619 Set the position in the history list to
<VAR>pos
</VAR>, an absolute index
626 <DT><U>Function:
</U> HIST_ENTRY *
<B>previous_history
</B> <I>()
</I>
627 <DD><A NAME=
"IDX20"></A>
628 Back up the current history offset to the previous history entry, and
629 return a pointer to that entry. If there is no previous entry, return
630 a
<CODE>NULL
</CODE> pointer.
636 <DT><U>Function:
</U> HIST_ENTRY *
<B>next_history
</B> <I>()
</I>
637 <DD><A NAME=
"IDX21"></A>
638 Move the current history offset forward to the next history entry, and
639 return the a pointer to that entry. If there is no next entry, return
640 a
<CODE>NULL
</CODE> pointer.
646 <H3><A NAME=
"SEC14" HREF=
"history.html#TOC14">Searching the History List
</A></H3>
652 These functions allow searching of the history list for entries containing
653 a specific string. Searching may be performed both forward and backward
654 from the current history position. The search may be
<EM>anchored
</EM>,
655 meaning that the string must match at the beginning of the history entry.
661 <DT><U>Function:
</U> int
<B>history_search
</B> <I>(char *string, int direction)
</I>
662 <DD><A NAME=
"IDX24"></A>
663 Search the history for
<VAR>string
</VAR>, starting at the current history
664 offset. If
<VAR>direction
</VAR> < 0, then the search is through previous entries,
665 else through subsequent. If
<VAR>string
</VAR> is found, then
666 the current history index is set to that history entry, and the value
667 returned is the offset in the line of the entry where
668 <VAR>string
</VAR> was found. Otherwise, nothing is changed, and a -
1 is
675 <DT><U>Function:
</U> int
<B>history_search_prefix
</B> <I>(char *string, int direction)
</I>
676 <DD><A NAME=
"IDX25"></A>
677 Search the history for
<VAR>string
</VAR>, starting at the current history
678 offset. The search is anchored: matching lines must begin with
679 <VAR>string
</VAR>. If
<VAR>direction
</VAR> < 0, then the search is through previous
680 entries, else through subsequent. If
<VAR>string
</VAR> is found, then the
681 current history index is set to that entry, and the return value is
0.
682 Otherwise, nothing is changed, and a -
1 is returned.
688 <DT><U>Function:
</U> int
<B>history_search_pos
</B> <I>(char *string, int direction, int pos)
</I>
689 <DD><A NAME=
"IDX26"></A>
690 Search for
<VAR>string
</VAR> in the history list, starting at
<VAR>pos
</VAR>, an
691 absolute index into the list. If
<VAR>direction
</VAR> is negative, the search
692 proceeds backward from
<VAR>pos
</VAR>, otherwise forward. Returns the absolute
693 index of the history element where
<VAR>string
</VAR> was found, or -
1 otherwise.
699 <H3><A NAME=
"SEC15" HREF=
"history.html#TOC15">Managing the History File
</A></H3>
702 The History library can read the history from and write it to a file.
703 This section documents the functions for managing a history file.
708 <DT><U>Function:
</U> int
<B>read_history
</B> <I>(char *filename)
</I>
709 <DD><A NAME=
"IDX27"></A>
710 Add the contents of
<VAR>filename
</VAR> to the history list, a line at a
711 time. If
<VAR>filename
</VAR> is
<CODE>NULL
</CODE>, then read from
712 <TT>`~/.history'
</TT>. Returns
0 if successful, or errno if not.
718 <DT><U>Function:
</U> int
<B>read_history_range
</B> <I>(char *filename, int from, int to)
</I>
719 <DD><A NAME=
"IDX28"></A>
720 Read a range of lines from
<VAR>filename
</VAR>, adding them to the history list.
721 Start reading at line
<VAR>from
</VAR> and end at
<VAR>to
</VAR>. If
722 <VAR>from
</VAR> is zero, start at the beginning. If
<VAR>to
</VAR> is less than
723 <VAR>from
</VAR>, then read until the end of the file. If
<VAR>filename
</VAR> is
724 <CODE>NULL
</CODE>, then read from
<TT>`~/.history'
</TT>. Returns
0 if successful,
725 or
<CODE>errno
</CODE> if not.
731 <DT><U>Function:
</U> int
<B>write_history
</B> <I>(char *filename)
</I>
732 <DD><A NAME=
"IDX29"></A>
733 Write the current history to
<VAR>filename
</VAR>, overwriting
<VAR>filename
</VAR>
734 if necessary. If
<VAR>filename
</VAR> is
735 <CODE>NULL
</CODE>, then write the history list to
<TT>`~/.history'
</TT>. Values
736 returned are as in
<CODE>read_history ()
</CODE>.
742 <DT><U>Function:
</U> int
<B>append_history
</B> <I>(int nelements, char *filename)
</I>
743 <DD><A NAME=
"IDX30"></A>
744 Append the last
<VAR>nelements
</VAR> of the history list to
<VAR>filename
</VAR>.
750 <DT><U>Function:
</U> int
<B>history_truncate_file
</B> <I>(char *filename, int nlines)
</I>
751 <DD><A NAME=
"IDX31"></A>
752 Truncate the history file
<VAR>filename
</VAR>, leaving only the last
753 <VAR>nlines
</VAR> lines.
759 <H3><A NAME=
"SEC16" HREF=
"history.html#TOC16">History Expansion
</A></H3>
762 These functions implement
<CODE>csh
</CODE>-like history expansion.
767 <DT><U>Function:
</U> int
<B>history_expand
</B> <I>(char *string, char **output)
</I>
768 <DD><A NAME=
"IDX32"></A>
769 Expand
<VAR>string
</VAR>, placing the result into
<VAR>output
</VAR>, a pointer
770 to a string (see section
<A HREF=
"history.html#SEC2">History Expansion
</A>). Returns:
775 If no expansions took place (or, if the only change in
776 the text was the de-slashifying of the history expansion
780 if expansions did take place;
783 if there was an error in expansion;
786 if the returned line should only be displayed, but not executed,
787 as with the
<CODE>:p
</CODE> modifier (see section
<A HREF=
"history.html#SEC5">Modifiers
</A>).
791 If an error ocurred in expansion, then
<VAR>output
</VAR> contains a descriptive
798 <DT><U>Function:
</U> char *
<B>history_arg_extract
</B> <I>(int first, int last, char *string)
</I>
799 <DD><A NAME=
"IDX33"></A>
800 Extract a string segment consisting of the
<VAR>first
</VAR> through
<VAR>last
</VAR>
801 arguments present in
<VAR>string
</VAR>. Arguments are broken up as in Bash.
807 <DT><U>Function:
</U> char *
<B>get_history_event
</B> <I>(char *string, int *cindex, int qchar)
</I>
808 <DD><A NAME=
"IDX34"></A>
809 Returns the text of the history event beginning at
<VAR>string
</VAR> +
810 <VAR>*cindex
</VAR>.
<VAR>*cindex
</VAR> is modified to point to after the event
811 specifier. At function entry,
<VAR>cindex
</VAR> points to the index into
812 <VAR>string
</VAR> where the history event specification begins.
<VAR>qchar
</VAR>
813 is a character that is allowed to end the event specification in addition
814 to the
"normal" terminating characters.
820 <DT><U>Function:
</U> char **
<B>history_tokenize
</B> <I>(char *string)
</I>
821 <DD><A NAME=
"IDX35"></A>
822 Return an array of tokens parsed out of
<VAR>string
</VAR>, much as the
823 shell might. The tokens are split on white space and on the
824 characters
<CODE>()
<>;
&|$
</CODE>, and shell quoting conventions are
831 <H2><A NAME=
"SEC17" HREF=
"history.html#TOC17">History Variables
</A></H2>
834 This section describes the externally visible variables exported by
835 the GNU History Library.
840 <DT><U>Variable:
</U> int
<B>history_base
</B>
841 <DD><A NAME=
"IDX36"></A>
842 The logical offset of the first entry in the history list.
848 <DT><U>Variable:
</U> int
<B>history_length
</B>
849 <DD><A NAME=
"IDX37"></A>
850 The number of entries currently stored in the history list.
856 <DT><U>Variable:
</U> int
<B>max_input_history
</B>
857 <DD><A NAME=
"IDX38"></A>
858 The maximum number of history entries. This must be changed using
859 <CODE>stifle_history ()
</CODE>.
865 <DT><U>Variable:
</U> char
<B>history_expansion_char
</B>
866 <DD><A NAME=
"IDX39"></A>
867 The character that starts a history event. The default is
<SAMP>`!'
</SAMP>.
873 <DT><U>Variable:
</U> char
<B>history_subst_char
</B>
874 <DD><A NAME=
"IDX40"></A>
875 The character that invokes word substitution if found at the start of
876 a line. The default is
<SAMP>`^'
</SAMP>.
882 <DT><U>Variable:
</U> char
<B>history_comment_char
</B>
883 <DD><A NAME=
"IDX41"></A>
884 During tokenization, if this character is seen as the first character
885 of a word, then it and all subsequent characters up to a newline are
886 ignored, suppressing history expansion for the remainder of the line.
887 This is disabled by default.
893 <DT><U>Variable:
</U> char *
<B>history_no_expand_chars
</B>
894 <DD><A NAME=
"IDX42"></A>
895 The list of characters which inhibit history expansion if found immediately
896 following
<VAR>history_expansion_char
</VAR>. The default is whitespace and
903 <DT><U>Variable:
</U> char *
<B>history_search_delimiter_chars
</B>
904 <DD><A NAME=
"IDX43"></A>
905 The list of additional characters which can delimit a history search
906 string, in addition to whitespace,
<SAMP>`:'
</SAMP> and
<SAMP>`?'
</SAMP> in the case of
907 a substring search. The default is empty.
913 <DT><U>Variable:
</U> int
<B>history_quotes_inhibit_expansion
</B>
914 <DD><A NAME=
"IDX44"></A>
915 If non-zero, single-quoted words are not scanned for the history expansion
916 character. The default value is
0.
922 <DT><U>Variable:
</U> Function *
<B>history_inhibit_expansion_function
</B>
923 <DD><A NAME=
"IDX45"></A>
924 This should be set to the address of a function that takes two arguments:
925 a
<CODE>char *
</CODE> (
<VAR>string
</VAR>) and an integer index into that string (
<VAR>i
</VAR>).
926 It should return a non-zero value if the history expansion starting at
927 <VAR>string[i]
</VAR> should not be performed; zero if the expansion should
929 It is intended for use by applications like Bash that use the history
930 expansion character for additional purposes.
931 By default, this variable is set to NULL.
937 <H2><A NAME=
"SEC18" HREF=
"history.html#TOC18">History Programming Example
</A></H2>
940 The following program demonstrates simple use of the GNU History Library.
955 printf (
"history$ ");
957 t = fgets (line, sizeof (line) -
1, stdin);
961 if (t[len -
1] == '\n')
966 strcpy (line,
"quit");
973 result = history_expand (line,
&expansion);
975 fprintf (stderr,
"%s\n", expansion);
977 if (result
< 0 || result ==
2)
983 add_history (expansion);
984 strncpy (line, expansion, sizeof (line) -
1);
988 if (strcmp (line,
"quit") ==
0)
990 else if (strcmp (line,
"save") ==
0)
991 write_history (
"history_file");
992 else if (strcmp (line,
"read") ==
0)
993 read_history (
"history_file");
994 else if (strcmp (line,
"list") ==
0)
996 register HIST_ENTRY **the_list;
999 the_list = history_list ();
1001 for (i =
0; the_list[i]; i++)
1002 printf (
"%d: %s\n", i + history_base, the_list[i]-
>line);
1004 else if (strncmp (line,
"delete",
6) ==
0)
1007 if ((sscanf (line +
6,
"%d",
&which)) ==
1)
1009 HIST_ENTRY *entry = remove_history (which);
1011 fprintf (stderr,
"No such entry %d\n", which);
1014 free (entry-
>line);
1020 fprintf (stderr,
"non-numeric arg given to `delete'\n");
1029 <H1><A NAME=
"SEC19" HREF=
"history.html#TOC19">Concept Index
</A></H1>
1038 <H2><A NAME=
"a">a
</A></H2>
1040 <LI><A HREF=
"history.html#IDX23">anchored search
</A>
1042 <H2><A NAME=
"e">e
</A></H2>
1044 <LI><A HREF=
"history.html#IDX2">event designators
</A>
1046 <H2><A NAME=
"h">h
</A></H2>
1048 <LI><A HREF=
"history.html#IDX3">history events
</A>
1049 <LI><A HREF=
"history.html#IDX1">history expansion
</A>
1050 <LI><A HREF=
"history.html#IDX22">History Searching
</A>
1056 <H1><A NAME=
"SEC20" HREF=
"history.html#TOC20">Function and Variable Index
</A></H1>
1081 <H2><A NAME=
"a">a
</A></H2>
1083 <LI><A HREF=
"history.html#IDX7">add_history
</A>
1084 <LI><A HREF=
"history.html#IDX30">append_history
</A>
1086 <H2><A NAME=
"c">c
</A></H2>
1088 <LI><A HREF=
"history.html#IDX10">clear_history
</A>
1089 <LI><A HREF=
"history.html#IDX16">current_history
</A>
1091 <H2><A NAME=
"g">g
</A></H2>
1093 <LI><A HREF=
"history.html#IDX34">get_history_event
</A>
1095 <H2><A NAME=
"h">h
</A></H2>
1097 <LI><A HREF=
"history.html#IDX33">history_arg_extract
</A>
1098 <LI><A HREF=
"history.html#IDX36">history_base
</A>
1099 <LI><A HREF=
"history.html#IDX41">history_comment_char
</A>
1100 <LI><A HREF=
"history.html#IDX32">history_expand
</A>
1101 <LI><A HREF=
"history.html#IDX39">history_expansion_char
</A>
1102 <LI><A HREF=
"history.html#IDX17">history_get
</A>
1103 <LI><A HREF=
"history.html#IDX5">history_get_history_state
</A>
1104 <LI><A HREF=
"history.html#IDX45">history_inhibit_expansion_function
</A>
1105 <LI><A HREF=
"history.html#IDX13">history_is_stifled
</A>
1106 <LI><A HREF=
"history.html#IDX37">history_length
</A>
1107 <LI><A HREF=
"history.html#IDX14">history_list
</A>
1108 <LI><A HREF=
"history.html#IDX42">history_no_expand_chars
</A>
1109 <LI><A HREF=
"history.html#IDX44">history_quotes_inhibit_expansion
</A>
1110 <LI><A HREF=
"history.html#IDX24">history_search
</A>
1111 <LI><A HREF=
"history.html#IDX43">history_search_delimiter_chars
</A>
1112 <LI><A HREF=
"history.html#IDX26">history_search_pos
</A>
1113 <LI><A HREF=
"history.html#IDX25">history_search_prefix
</A>
1114 <LI><A HREF=
"history.html#IDX6">history_set_history_state
</A>
1115 <LI><A HREF=
"history.html#IDX19">history_set_pos
</A>
1116 <LI><A HREF=
"history.html#IDX40">history_subst_char
</A>
1117 <LI><A HREF=
"history.html#IDX35">history_tokenize
</A>
1118 <LI><A HREF=
"history.html#IDX18">history_total_bytes
</A>
1119 <LI><A HREF=
"history.html#IDX31">history_truncate_file
</A>
1121 <H2><A NAME=
"m">m
</A></H2>
1123 <LI><A HREF=
"history.html#IDX38">max_input_history
</A>
1125 <H2><A NAME=
"n">n
</A></H2>
1127 <LI><A HREF=
"history.html#IDX21">next_history
</A>
1129 <H2><A NAME=
"p">p
</A></H2>
1131 <LI><A HREF=
"history.html#IDX20">previous_history
</A>
1133 <H2><A NAME=
"r">r
</A></H2>
1135 <LI><A HREF=
"history.html#IDX27">read_history
</A>
1136 <LI><A HREF=
"history.html#IDX28">read_history_range
</A>
1137 <LI><A HREF=
"history.html#IDX8">remove_history
</A>
1138 <LI><A HREF=
"history.html#IDX9">replace_history_entry
</A>
1140 <H2><A NAME=
"s">s
</A></H2>
1142 <LI><A HREF=
"history.html#IDX11">stifle_history
</A>
1144 <H2><A NAME=
"u">u
</A></H2>
1146 <LI><A HREF=
"history.html#IDX12">unstifle_history
</A>
1147 <LI><A HREF=
"history.html#IDX4">using_history
</A>
1149 <H2><A NAME=
"w">w
</A></H2>
1151 <LI><A HREF=
"history.html#IDX15">where_history
</A>
1152 <LI><A HREF=
"history.html#IDX29">write_history
</A>
1157 This document was generated on
31 December
1998 using the
1158 <A HREF=
"http://wwwinfo.cern.ch/dis/texi2html/">texi2html
</A>
1159 translator version
1.52.
</P>