2 .\" MAN PAGE COMMENTS to
5 .\" Information Network Services
6 .\" Case Western Reserve University
9 .\" Last Change: Thu Jul 31 08:46:08 EDT 2003
11 .TH HISTORY 3 "2003 July 31" "GNU History 5.0"
13 .\" File Name macro. This used to be `.PN', for Path Name,
14 .\" but Sun doesn't seem to like that very much.
21 .\" FnN return-value fun-name N arguments
23 \fI\\$1\fP \fB\\$2\fP \\*(lp\fI\\$3\fP\\*(rp
27 .if t \fI\\$1\fP \fB\\$2\fP \\*(lp\fI\\$3,\|\\$4\fP\\*(rp
28 .if n \fI\\$1\fP \fB\\$2\fP \\*(lp\fI\\$3, \\$4\fP\\*(rp
32 .if t \fI\\$1\fP \fB\\$2\fP \\*(lp\fI\\$3,\|\\$4,\|\\$5\fP\|\\*(rp
33 .if n \fI\\$1\fP \fB\\$2\fP \\*(lp\fI\\$3, \\$4, \\$5\fP\\*(rp
41 history \- GNU History Library
43 .if t The GNU History Library is Copyright \(co 1989-2002 by the Free Software Foundation, Inc.
44 .if n The GNU History Library is Copyright (C) 1989-2002 by the Free Software Foundation, Inc.
46 Many programs read input from the user a line at a time. The GNU
47 History library is able to keep track of those lines, associate arbitrary
48 data with each line, and utilize information from previous lines in
51 .SH "HISTORY EXPANSION"
53 The history library supports a history expansion feature that
54 is identical to the history expansion in
56 This section describes what syntax features are available.
58 History expansions introduce words from the history list into
59 the input stream, making it easy to repeat commands, insert the
60 arguments to a previous command into the current input line, or
61 fix errors in previous commands quickly.
63 History expansion is usually performed immediately after a complete line
65 It takes place in two parts.
66 The first is to determine which line from the history list
67 to use during substitution.
68 The second is to select portions of that line for inclusion into
70 The line selected from the history is the \fIevent\fP,
71 and the portions of that line that are acted upon are \fIwords\fP.
72 Various \fImodifiers\fP are available to manipulate the selected words.
73 The line is broken into words in the same fashion as \fBbash\fP
74 does when reading input,
75 so that several words that would otherwise be separated
76 are considered one word when surrounded by quotes (see the
77 description of \fBhistory_tokenize()\fP below).
78 History expansions are introduced by the appearance of the
79 history expansion character, which is \^\fB!\fP\^ by default.
80 Only backslash (\^\fB\e\fP\^) and single quotes can quote
81 the history expansion character.
84 An event designator is a reference to a command line entry in the
90 Start a history substitution, except when followed by a
99 Refer to the current command line minus
103 Refer to the previous command. This is a synonym for `!\-1'.
106 Refer to the most recent command starting with
109 .B !?\fIstring\fR\fB[?]\fR
110 Refer to the most recent command containing
112 The trailing \fB?\fP may be omitted if
114 is followed immediately by a newline.
116 .B \d\s+2^\s-2\u\fIstring1\fP\d\s+2^\s-2\u\fIstring2\fP\d\s+2^\s-2\u
117 Quick substitution. Repeat the last command, replacing
122 ``!!:s/\fIstring1\fP/\fIstring2\fP/''
123 (see \fBModifiers\fP below).
126 The entire command line typed so far.
130 Word designators are used to select desired words from the event.
133 separates the event specification from the word designator.
134 It may be omitted if the word designator begins with a
141 Words are numbered from the beginning of the line,
142 with the first word being denoted by 0 (zero).
143 Words are inserted into the current line separated by single spaces.
148 The zeroth word. For the shell, this is the command
155 The first argument. That is, word 1.
161 The word matched by the most recent `?\fIstring\fR?' search.
164 A range of words; `\-\fIy\fR' abbreviates `0\-\fIy\fR'.
167 All of the words but the zeroth. This is a synonym
168 for `\fI1\-$\fP'. It is not an error to use
171 word in the event; the empty string is returned in that case.
174 Abbreviates \fIx\-$\fP.
177 Abbreviates \fIx\-$\fP like \fBx*\fP, but omits the last word.
180 If a word designator is supplied without an event specification, the
181 previous command is used as the event.
184 After the optional word designator, there may appear a sequence of
185 one or more of the following modifiers, each preceded by a `:'.
191 Remove a trailing file name component, leaving only the head.
194 Remove all leading file name components, leaving the tail.
197 Remove a trailing suffix of the form \fI.xxx\fP, leaving the
201 Remove all but the trailing suffix.
204 Print the new command but do not execute it.
207 Quote the substituted words, escaping further substitutions.
210 Quote the substituted words as with
212 but break into words at
216 .B s/\fIold\fP/\fInew\fP/
219 for the first occurrence of
221 in the event line. Any delimiter can be used in place of /. The
222 final delimiter is optional if it is the last character of the
223 event line. The delimiter may be quoted in
227 with a single backslash. If & appears in
231 A single backslash will quote the &. If
233 is null, it is set to the last
235 substituted, or, if no previous history substitutions took place,
239 .B !?\fIstring\fR\fB[?]\fR
243 Repeat the previous substitution.
246 Cause changes to be applied over the entire event line. This is
247 used in conjunction with `\fB:s\fP' (e.g., `\fB:gs/\fIold\fP/\fInew\fP/\fR')
248 or `\fB:&\fP'. If used with
249 `\fB:s\fP', any delimiter can be used
250 in place of /, and the final delimiter is optional
251 if it is the last character of the event line.
252 An \fBa\fP may be used as a synonym for \fBg\fP.
255 Apply the following `\fBs\fP' modifier once to each word in the event line.
257 .SH "PROGRAMMING WITH HISTORY FUNCTIONS"
258 This section describes how to use the History library in other programs.
259 .SS Introduction to History
261 The programmer using the History library has available functions
262 for remembering lines on a history list, associating arbitrary data
263 with a line, removing lines from the list, searching through the list
264 for a line containing an arbitrary text string, and referencing any line
265 in the list directly. In addition, a history \fIexpansion\fP function
266 is available which provides for a consistent user interface across
269 The user using programs written with the History library has the
270 benefit of a consistent user interface with a set of well-known
271 commands for manipulating the text of previous lines and using that text
272 in new commands. The basic history manipulation commands are
274 the history substitution provided by \fBbash\fP.
276 If the programmer desires, he can use the Readline library, which
277 includes some history manipulation by default, and has the added
278 advantage of command line editing.
280 Before declaring any functions using any functionality the History
281 library provides in other code, an application writer should include
283 .FN <readline/history.h>
284 in any file that uses the
285 History library's features. It supplies extern declarations for all
286 of the library's public functions and variables, and declares all of
287 the public data structures.
291 The history list is an array of history entries. A history entry is
294 .Vb "typedef void *" histdata_t;
297 typedef struct _hist_entry {
304 The history list itself might therefore be declared as
306 .Vb "HIST_ENTRY **" the_history_list;
308 The state of the History library is encapsulated into a single structure:
312 * A structure used to pass around the current state of the history.
314 typedef struct _hist_state {
315 HIST_ENTRY **entries; /* Pointer to the entries themselves. */
316 int offset; /* The location pointer within this array. */
317 int length; /* Number of elements within this array. */
318 int size; /* Number of slots allocated to this array. */
323 If the flags member includes \fBHS_STIFLED\fP, the history has been
325 .SH "History Functions"
327 This section describes the calling sequence for the various functions
328 exported by the GNU History library.
329 .SS Initializing History and State Management
330 This section describes functions used to initialize and manage
331 the state of the History library when you want to use the history
332 functions in your program.
334 .Fn1 void using_history void
335 Begin a session in which the history functions might be used. This
336 initializes the interactive variables.
338 .Fn1 "HISTORY_STATE *" history_get_history_state void
339 Return a structure describing the current state of the input history.
341 .Fn1 void history_set_history_state "HISTORY_STATE *state"
342 Set the state of the history list according to \fIstate\fP.
344 .SS History List Management
346 These functions manage individual entries on the history list, or set
347 parameters managing the list itself.
349 .Fn1 void add_history "const char *string"
350 Place \fIstring\fP at the end of the history list. The associated data
351 field (if any) is set to \fBNULL\fP.
353 .Fn1 void add_history_time "const char *string"
354 Change the time stamp associated with the most recent history entry to
357 .Fn1 "HIST_ENTRY *" remove_history "int which"
358 Remove history entry at offset \fIwhich\fP from the history. The
359 removed element is returned so you can free the line, data,
360 and containing structure.
362 .Fn1 "histdata_t" free_history_entry "HIST_ENTRY *histent"
363 Free the history entry \fIhistent\fP and any history library private
364 data associated with it. Returns the application-specific data
365 so the caller can dispose of it.
367 .Fn3 "HIST_ENTRY *" replace_history_entry "int which" "const char *line" "histdata_t data"
368 Make the history entry at offset \fIwhich\fP have \fIline\fP and \fIdata\fP.
369 This returns the old entry so the caller can dispose of any
370 application-specific data. In the case
371 of an invalid \fIwhich\fP, a \fBNULL\fP pointer is returned.
373 .Fn1 void clear_history "void"
374 Clear the history list by deleting all the entries.
376 .Fn1 void stifle_history "int max"
377 Stifle the history list, remembering only the last \fImax\fP entries.
379 .Fn1 int unstifle_history "void"
380 Stop stifling the history. This returns the previously-set
381 maximum number of history entries (as set by \fBstifle_history()\fP).
382 history was stifled. The value is positive if the history was
383 stifled, negative if it wasn't.
385 .Fn1 int history_is_stifled "void"
386 Returns non-zero if the history is stifled, zero if it is not.
388 .SS Information About the History List
390 These functions return information about the entire history list or
391 individual list entries.
393 .Fn1 "HIST_ENTRY **" history_list "void"
394 Return a \fBNULL\fP terminated array of \fIHIST_ENTRY *\fP which is the
395 current input history. Element 0 of this list is the beginning of time.
396 If there is no history, return \fBNULL\fP.
398 .Fn1 int where_history "void"
399 Returns the offset of the current history element.
401 .Fn1 "HIST_ENTRY *" current_history "void"
402 Return the history entry at the current position, as determined by
403 \fBwhere_history()\fP. If there is no entry there, return a \fBNULL\fP
406 .Fn1 "HIST_ENTRY *" history_get "int offset"
407 Return the history entry at position \fIoffset\fP, starting from
409 If there is no entry there, or if \fIoffset\fP
410 is greater than the history length, return a \fBNULL\fP pointer.
412 .Fn1 "time_t" history_get_time "HIST_ENTRY *"
413 Return the time stamp associated with the history entry passed as the argument.
415 .Fn1 int history_total_bytes "void"
416 Return the number of bytes that the primary history entries are using.
417 This function returns the sum of the lengths of all the lines in the
420 .SS Moving Around the History List
422 These functions allow the current index into the history list to be
425 .Fn1 int history_set_pos "int pos"
426 Set the current history offset to \fIpos\fP, an absolute index
428 Returns 1 on success, 0 if \fIpos\fP is less than zero or greater
429 than the number of history entries.
431 .Fn1 "HIST_ENTRY *" previous_history "void"
432 Back up the current history offset to the previous history entry, and
433 return a pointer to that entry. If there is no previous entry, return
434 a \fBNULL\fP pointer.
436 .Fn1 "HIST_ENTRY *" next_history "void"
437 Move the current history offset forward to the next history entry, and
438 return the a pointer to that entry. If there is no next entry, return
439 a \fBNULL\fP pointer.
441 .SS Searching the History List
443 These functions allow searching of the history list for entries containing
444 a specific string. Searching may be performed both forward and backward
445 from the current history position. The search may be \fIanchored\fP,
446 meaning that the string must match at the beginning of the history entry.
448 .Fn2 int history_search "const char *string" "int direction"
449 Search the history for \fIstring\fP, starting at the current history offset.
450 If \fIdirection\fP is less than 0, then the search is through
451 previous entries, otherwise through subsequent entries.
452 If \fIstring\fP is found, then
453 the current history index is set to that history entry, and the value
454 returned is the offset in the line of the entry where
455 \fIstring\fP was found. Otherwise, nothing is changed, and a -1 is
458 .Fn2 int history_search_prefix "const char *string" "int direction"
459 Search the history for \fIstring\fP, starting at the current history
460 offset. The search is anchored: matching lines must begin with
461 \fIstring\fP. If \fIdirection\fP is less than 0, then the search is
462 through previous entries, otherwise through subsequent entries.
463 If \fIstring\fP is found, then the
464 current history index is set to that entry, and the return value is 0.
465 Otherwise, nothing is changed, and a -1 is returned.
467 .Fn3 int history_search_pos "const char *string" "int direction" "int pos"
468 Search for \fIstring\fP in the history list, starting at \fIpos\fP, an
469 absolute index into the list. If \fIdirection\fP is negative, the search
470 proceeds backward from \fIpos\fP, otherwise forward. Returns the absolute
471 index of the history element where \fIstring\fP was found, or -1 otherwise.
473 .SS Managing the History File
474 The History library can read the history from and write it to a file.
475 This section documents the functions for managing a history file.
477 .Fn1 int read_history "const char *filename"
478 Add the contents of \fIfilename\fP to the history list, a line at a time.
479 If \fIfilename\fP is \fBNULL\fP, then read from \fI~/.history\fP.
480 Returns 0 if successful, or \fBerrno\fP if not.
482 .Fn3 int read_history_range "const char *filename" "int from" "int to"
483 Read a range of lines from \fIfilename\fP, adding them to the history list.
484 Start reading at line \fIfrom\fP and end at \fIto\fP.
485 If \fIfrom\fP is zero, start at the beginning. If \fIto\fP is less than
486 \fIfrom\fP, then read until the end of the file. If \fIfilename\fP is
487 \fBNULL\fP, then read from \fI~/.history\fP. Returns 0 if successful,
488 or \fBerrno\fP if not.
490 .Fn1 int write_history "const char *filename"
491 Write the current history to \fIfilename\fP, overwriting \fIfilename\fP
493 If \fIfilename\fP is \fBNULL\fP, then write the history list to \fI~/.history\fP.
494 Returns 0 on success, or \fBerrno\fP on a read or write error.
497 .Fn2 int append_history "int nelements" "const char *filename"
498 Append the last \fInelements\fP of the history list to \fIfilename\fP.
499 If \fIfilename\fP is \fBNULL\fP, then append to \fI~/.history\fP.
500 Returns 0 on success, or \fBerrno\fP on a read or write error.
502 .Fn2 int history_truncate_file "const char *filename" "int nlines"
503 Truncate the history file \fIfilename\fP, leaving only the last
505 If \fIfilename\fP is \fBNULL\fP, then \fI~/.history\fP is truncated.
506 Returns 0 on success, or \fBerrno\fP on failure.
508 .SS History Expansion
510 These functions implement history expansion.
512 .Fn2 int history_expand "char *string" "char **output"
513 Expand \fIstring\fP, placing the result into \fIoutput\fP, a pointer
514 to a string. Returns:
519 If no expansions took place (or, if the only change in
520 the text was the removal of escape characters preceding the history expansion
524 if expansions did take place;
527 if there was an error in expansion;
530 if the returned line should be displayed, but not executed,
531 as with the \fB:p\fP modifier.
534 If an error ocurred in expansion, then \fIoutput\fP contains a descriptive
537 .Fn3 "char *" get_history_event "const char *string" "int *cindex" "int qchar"
538 Returns the text of the history event beginning at \fIstring\fP +
539 \fI*cindex\fP. \fI*cindex\fP is modified to point to after the event
540 specifier. At function entry, \fIcindex\fP points to the index into
541 \fIstring\fP where the history event specification begins. \fIqchar\fP
542 is a character that is allowed to end the event specification in addition
543 to the ``normal'' terminating characters.
545 .Fn1 "char **" history_tokenize "const char *string"
546 Return an array of tokens parsed out of \fIstring\fP, much as the
548 The tokens are split on the characters in the
549 \fBhistory_word_delimiters\fP variable,
550 and shell quoting conventions are obeyed.
552 .Fn3 "char *" history_arg_extract "int first" "int last" "const char *string"
553 Extract a string segment consisting of the \fIfirst\fP through \fIlast\fP
554 arguments present in \fIstring\fP. Arguments are split using
555 \fBhistory_tokenize()\fP.
557 .SS History Variables
559 This section describes the externally-visible variables exported by
560 the GNU History Library.
563 The logical offset of the first entry in the history list.
565 .Vb int history_length
566 The number of entries currently stored in the history list.
568 .Vb int history_max_entries
569 The maximum number of history entries. This must be changed using
570 \fBstifle_history()\fP.
572 .Vb int history_write_timestamps
573 If non-zero, timestamps are written to the history file, so they can be
574 preserved between sessions. The default value is 0, meaning that
575 timestamps are not saved.
577 .Vb char history_expansion_char
578 The character that introduces a history event. The default is \fB!\fP.
579 Setting this to 0 inhibits history expansion.
581 .Vb char history_subst_char
582 The character that invokes word substitution if found at the start of
583 a line. The default is \fB^\fP.
585 .Vb char history_comment_char
586 During tokenization, if this character is seen as the first character
587 of a word, then it and all subsequent characters up to a newline are
588 ignored, suppressing history expansion for the remainder of the line.
589 This is disabled by default.
591 .Vb "char *" history_word_delimiters
592 The characters that separate tokens for \fBhistory_tokenize()\fP.
593 The default value is \fB"\ \et\en()<>;&|"\fP.
595 .Vb "char *" history_no_expand_chars
596 The list of characters which inhibit history expansion if found immediately
597 following \fBhistory_expansion_char\fP. The default is space, tab, newline,
598 \fB\er\fP, and \fB=\fP.
600 .Vb "char *" history_search_delimiter_chars
601 The list of additional characters which can delimit a history search
602 string, in addition to space, tab, \fI:\fP and \fI?\fP in the case of
603 a substring search. The default is empty.
605 .Vb int history_quotes_inhibit_expansion
606 If non-zero, single-quoted words are not scanned for the history expansion
607 character. The default value is 0.
609 .Vb "rl_linebuf_func_t *" history_inhibit_expansion_function
610 This should be set to the address of a function that takes two arguments:
611 a \fBchar *\fP (\fIstring\fP)
612 and an \fBint\fP index into that string (\fIi\fP).
613 It should return a non-zero value if the history expansion starting at
614 \fIstring[i]\fP should not be performed; zero if the expansion should
616 It is intended for use by applications like \fBbash\fP that use the history
617 expansion character for additional purposes.
618 By default, this variable is set to \fBNULL\fP.
623 Default filename for reading and writing saved history
628 \fIThe Gnu Readline Library\fP, Brian Fox and Chet Ramey
630 \fIThe Gnu History Library\fP, Brian Fox and Chet Ramey
637 Brian Fox, Free Software Foundation
641 Chet Ramey, Case Western Reserve University
645 If you find a bug in the
647 library, you should report it. But first, you should
648 make sure that it really is a bug, and that it appears in the latest
651 library that you have.
653 Once you have determined that a bug actually exists, mail a
654 bug report to \fIbug\-readline\fP@\fIgnu.org\fP.
655 If you have a fix, you are welcome to mail that
656 as well! Suggestions and `philosophical' bug reports may be mailed
657 to \fPbug-readline\fP@\fIgnu.org\fP or posted to the Usenet
661 Comments and bug reports concerning
662 this manual page should be directed to
663 .IR chet@ins.CWRU.Edu .
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