2 .\" MAN PAGE COMMENTS to
5 .\" Information Network Services
6 .\" Case Western Reserve University
9 .\" Last Change: Thu Aug 12 22:24:41 EDT 2010
11 .TH HISTORY 3 "2010 August 12" "GNU History 6.2"
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 1989-2011 by the Free Software Foundation, Inc.
44 .if n The GNU History Library is Copyright (C) 1989-2011 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
86 Unless the reference is absolute, events are relative to the current
87 position in the history list.
92 Start a history substitution, except when followed by a
101 Refer to the current command minus
105 Refer to the previous command. This is a synonym for `!\-1'.
108 Refer to the most recent command
109 preceding the current position in the history list
113 .B !?\fIstring\fR\fB[?]\fR
114 Refer to the most recent command
115 preceding the current postition in the history list
118 The trailing \fB?\fP may be omitted if
120 is followed immediately by a newline.
122 .B \d\s+2^\s-2\u\fIstring1\fP\d\s+2^\s-2\u\fIstring2\fP\d\s+2^\s-2\u
123 Quick substitution. Repeat the last command, replacing
128 ``!!:s/\fIstring1\fP/\fIstring2\fP/''
129 (see \fBModifiers\fP below).
132 The entire command line typed so far.
136 Word designators are used to select desired words from the event.
139 separates the event specification from the word designator.
140 It may be omitted if the word designator begins with a
147 Words are numbered from the beginning of the line,
148 with the first word being denoted by 0 (zero).
149 Words are inserted into the current line separated by single spaces.
154 The zeroth word. For the shell, this is the command
161 The first argument. That is, word 1.
167 The word matched by the most recent `?\fIstring\fR?' search.
170 A range of words; `\-\fIy\fR' abbreviates `0\-\fIy\fR'.
173 All of the words but the zeroth. This is a synonym
174 for `\fI1\-$\fP'. It is not an error to use
177 word in the event; the empty string is returned in that case.
180 Abbreviates \fIx\-$\fP.
183 Abbreviates \fIx\-$\fP like \fBx*\fP, but omits the last word.
186 If a word designator is supplied without an event specification, the
187 previous command is used as the event.
190 After the optional word designator, there may appear a sequence of
191 one or more of the following modifiers, each preceded by a `:'.
197 Remove a trailing file name component, leaving only the head.
200 Remove all leading file name components, leaving the tail.
203 Remove a trailing suffix of the form \fI.xxx\fP, leaving the
207 Remove all but the trailing suffix.
210 Print the new command but do not execute it.
213 Quote the substituted words, escaping further substitutions.
216 Quote the substituted words as with
218 but break into words at
222 .B s/\fIold\fP/\fInew\fP/
225 for the first occurrence of
227 in the event line. Any delimiter can be used in place of /. The
228 final delimiter is optional if it is the last character of the
229 event line. The delimiter may be quoted in
233 with a single backslash. If & appears in
237 A single backslash will quote the &. If
239 is null, it is set to the last
241 substituted, or, if no previous history substitutions took place,
245 .B !?\fIstring\fR\fB[?]\fR
249 Repeat the previous substitution.
252 Cause changes to be applied over the entire event line. This is
253 used in conjunction with `\fB:s\fP' (e.g., `\fB:gs/\fIold\fP/\fInew\fP/\fR')
254 or `\fB:&\fP'. If used with
255 `\fB:s\fP', any delimiter can be used
256 in place of /, and the final delimiter is optional
257 if it is the last character of the event line.
258 An \fBa\fP may be used as a synonym for \fBg\fP.
261 Apply the following `\fBs\fP' modifier once to each word in the event line.
263 .SH "PROGRAMMING WITH HISTORY FUNCTIONS"
264 This section describes how to use the History library in other programs.
265 .SS Introduction to History
267 The programmer using the History library has available functions
268 for remembering lines on a history list, associating arbitrary data
269 with a line, removing lines from the list, searching through the list
270 for a line containing an arbitrary text string, and referencing any line
271 in the list directly. In addition, a history \fIexpansion\fP function
272 is available which provides for a consistent user interface across
275 The user using programs written with the History library has the
276 benefit of a consistent user interface with a set of well-known
277 commands for manipulating the text of previous lines and using that text
278 in new commands. The basic history manipulation commands are
280 the history substitution provided by \fBbash\fP.
282 If the programmer desires, he can use the Readline library, which
283 includes some history manipulation by default, and has the added
284 advantage of command line editing.
286 Before declaring any functions using any functionality the History
287 library provides in other code, an application writer should include
289 .FN <readline/history.h>
290 in any file that uses the
291 History library's features. It supplies extern declarations for all
292 of the library's public functions and variables, and declares all of
293 the public data structures.
297 The history list is an array of history entries. A history entry is
300 .Vb "typedef void *" histdata_t;
303 typedef struct _hist_entry {
310 The history list itself might therefore be declared as
312 .Vb "HIST_ENTRY **" the_history_list;
314 The state of the History library is encapsulated into a single structure:
318 * A structure used to pass around the current state of the history.
320 typedef struct _hist_state {
321 HIST_ENTRY **entries; /* Pointer to the entries themselves. */
322 int offset; /* The location pointer within this array. */
323 int length; /* Number of elements within this array. */
324 int size; /* Number of slots allocated to this array. */
329 If the flags member includes \fBHS_STIFLED\fP, the history has been
331 .SH "History Functions"
333 This section describes the calling sequence for the various functions
334 exported by the GNU History library.
335 .SS Initializing History and State Management
336 This section describes functions used to initialize and manage
337 the state of the History library when you want to use the history
338 functions in your program.
340 .Fn1 void using_history void
341 Begin a session in which the history functions might be used. This
342 initializes the interactive variables.
344 .Fn1 "HISTORY_STATE *" history_get_history_state void
345 Return a structure describing the current state of the input history.
347 .Fn1 void history_set_history_state "HISTORY_STATE *state"
348 Set the state of the history list according to \fIstate\fP.
350 .SS History List Management
352 These functions manage individual entries on the history list, or set
353 parameters managing the list itself.
355 .Fn1 void add_history "const char *string"
356 Place \fIstring\fP at the end of the history list. The associated data
357 field (if any) is set to \fBNULL\fP.
359 .Fn1 void add_history_time "const char *string"
360 Change the time stamp associated with the most recent history entry to
363 .Fn1 "HIST_ENTRY *" remove_history "int which"
364 Remove history entry at offset \fIwhich\fP from the history. The
365 removed element is returned so you can free the line, data,
366 and containing structure.
368 .Fn1 "histdata_t" free_history_entry "HIST_ENTRY *histent"
369 Free the history entry \fIhistent\fP and any history library private
370 data associated with it. Returns the application-specific data
371 so the caller can dispose of it.
373 .Fn3 "HIST_ENTRY *" replace_history_entry "int which" "const char *line" "histdata_t data"
374 Make the history entry at offset \fIwhich\fP have \fIline\fP and \fIdata\fP.
375 This returns the old entry so the caller can dispose of any
376 application-specific data. In the case
377 of an invalid \fIwhich\fP, a \fBNULL\fP pointer is returned.
379 .Fn1 void clear_history "void"
380 Clear the history list by deleting all the entries.
382 .Fn1 void stifle_history "int max"
383 Stifle the history list, remembering only the last \fImax\fP entries.
385 .Fn1 int unstifle_history "void"
386 Stop stifling the history. This returns the previously-set
387 maximum number of history entries (as set by \fBstifle_history()\fP).
388 history was stifled. The value is positive if the history was
389 stifled, negative if it wasn't.
391 .Fn1 int history_is_stifled "void"
392 Returns non-zero if the history is stifled, zero if it is not.
394 .SS Information About the History List
396 These functions return information about the entire history list or
397 individual list entries.
399 .Fn1 "HIST_ENTRY **" history_list "void"
400 Return a \fBNULL\fP terminated array of \fIHIST_ENTRY *\fP which is the
401 current input history. Element 0 of this list is the beginning of time.
402 If there is no history, return \fBNULL\fP.
404 .Fn1 int where_history "void"
405 Returns the offset of the current history element.
407 .Fn1 "HIST_ENTRY *" current_history "void"
408 Return the history entry at the current position, as determined by
409 \fBwhere_history()\fP. If there is no entry there, return a \fBNULL\fP
412 .Fn1 "HIST_ENTRY *" history_get "int offset"
413 Return the history entry at position \fIoffset\fP, starting from
415 If there is no entry there, or if \fIoffset\fP
416 is greater than the history length, return a \fBNULL\fP pointer.
418 .Fn1 "time_t" history_get_time "HIST_ENTRY *"
419 Return the time stamp associated with the history entry passed as the argument.
421 .Fn1 int history_total_bytes "void"
422 Return the number of bytes that the primary history entries are using.
423 This function returns the sum of the lengths of all the lines in the
426 .SS Moving Around the History List
428 These functions allow the current index into the history list to be
431 .Fn1 int history_set_pos "int pos"
432 Set the current history offset to \fIpos\fP, an absolute index
434 Returns 1 on success, 0 if \fIpos\fP is less than zero or greater
435 than the number of history entries.
437 .Fn1 "HIST_ENTRY *" previous_history "void"
438 Back up the current history offset to the previous history entry, and
439 return a pointer to that entry. If there is no previous entry, return
440 a \fBNULL\fP pointer.
442 .Fn1 "HIST_ENTRY *" next_history "void"
443 Move the current history offset forward to the next history entry, and
444 return the a pointer to that entry. If there is no next entry, return
445 a \fBNULL\fP pointer.
447 .SS Searching the History List
449 These functions allow searching of the history list for entries containing
450 a specific string. Searching may be performed both forward and backward
451 from the current history position. The search may be \fIanchored\fP,
452 meaning that the string must match at the beginning of the history entry.
454 .Fn2 int history_search "const char *string" "int direction"
455 Search the history for \fIstring\fP, starting at the current history offset.
456 If \fIdirection\fP is less than 0, then the search is through
457 previous entries, otherwise through subsequent entries.
458 If \fIstring\fP is found, then
459 the current history index is set to that history entry, and the value
460 returned is the offset in the line of the entry where
461 \fIstring\fP was found. Otherwise, nothing is changed, and a -1 is
464 .Fn2 int history_search_prefix "const char *string" "int direction"
465 Search the history for \fIstring\fP, starting at the current history
466 offset. The search is anchored: matching lines must begin with
467 \fIstring\fP. If \fIdirection\fP is less than 0, then the search is
468 through previous entries, otherwise through subsequent entries.
469 If \fIstring\fP is found, then the
470 current history index is set to that entry, and the return value is 0.
471 Otherwise, nothing is changed, and a -1 is returned.
473 .Fn3 int history_search_pos "const char *string" "int direction" "int pos"
474 Search for \fIstring\fP in the history list, starting at \fIpos\fP, an
475 absolute index into the list. If \fIdirection\fP is negative, the search
476 proceeds backward from \fIpos\fP, otherwise forward. Returns the absolute
477 index of the history element where \fIstring\fP was found, or -1 otherwise.
479 .SS Managing the History File
480 The History library can read the history from and write it to a file.
481 This section documents the functions for managing a history file.
483 .Fn1 int read_history "const char *filename"
484 Add the contents of \fIfilename\fP to the history list, a line at a time.
485 If \fIfilename\fP is \fBNULL\fP, then read from \fI~/.history\fP.
486 Returns 0 if successful, or \fBerrno\fP if not.
488 .Fn3 int read_history_range "const char *filename" "int from" "int to"
489 Read a range of lines from \fIfilename\fP, adding them to the history list.
490 Start reading at line \fIfrom\fP and end at \fIto\fP.
491 If \fIfrom\fP is zero, start at the beginning. If \fIto\fP is less than
492 \fIfrom\fP, then read until the end of the file. If \fIfilename\fP is
493 \fBNULL\fP, then read from \fI~/.history\fP. Returns 0 if successful,
494 or \fBerrno\fP if not.
496 .Fn1 int write_history "const char *filename"
497 Write the current history to \fIfilename\fP, overwriting \fIfilename\fP
499 If \fIfilename\fP is \fBNULL\fP, then write the history list to \fI~/.history\fP.
500 Returns 0 on success, or \fBerrno\fP on a read or write error.
503 .Fn2 int append_history "int nelements" "const char *filename"
504 Append the last \fInelements\fP of the history list to \fIfilename\fP.
505 If \fIfilename\fP is \fBNULL\fP, then append to \fI~/.history\fP.
506 Returns 0 on success, or \fBerrno\fP on a read or write error.
508 .Fn2 int history_truncate_file "const char *filename" "int nlines"
509 Truncate the history file \fIfilename\fP, leaving only the last
511 If \fIfilename\fP is \fBNULL\fP, then \fI~/.history\fP is truncated.
512 Returns 0 on success, or \fBerrno\fP on failure.
514 .SS History Expansion
516 These functions implement history expansion.
518 .Fn2 int history_expand "char *string" "char **output"
519 Expand \fIstring\fP, placing the result into \fIoutput\fP, a pointer
520 to a string. Returns:
525 If no expansions took place (or, if the only change in
526 the text was the removal of escape characters preceding the history expansion
530 if expansions did take place;
533 if there was an error in expansion;
536 if the returned line should be displayed, but not executed,
537 as with the \fB:p\fP modifier.
540 If an error ocurred in expansion, then \fIoutput\fP contains a descriptive
543 .Fn3 "char *" get_history_event "const char *string" "int *cindex" "int qchar"
544 Returns the text of the history event beginning at \fIstring\fP +
545 \fI*cindex\fP. \fI*cindex\fP is modified to point to after the event
546 specifier. At function entry, \fIcindex\fP points to the index into
547 \fIstring\fP where the history event specification begins. \fIqchar\fP
548 is a character that is allowed to end the event specification in addition
549 to the ``normal'' terminating characters.
551 .Fn1 "char **" history_tokenize "const char *string"
552 Return an array of tokens parsed out of \fIstring\fP, much as the
554 The tokens are split on the characters in the
555 \fBhistory_word_delimiters\fP variable,
556 and shell quoting conventions are obeyed.
558 .Fn3 "char *" history_arg_extract "int first" "int last" "const char *string"
559 Extract a string segment consisting of the \fIfirst\fP through \fIlast\fP
560 arguments present in \fIstring\fP. Arguments are split using
561 \fBhistory_tokenize()\fP.
563 .SS History Variables
565 This section describes the externally-visible variables exported by
566 the GNU History Library.
569 The logical offset of the first entry in the history list.
571 .Vb int history_length
572 The number of entries currently stored in the history list.
574 .Vb int history_max_entries
575 The maximum number of history entries. This must be changed using
576 \fBstifle_history()\fP.
578 .Vb int history_wite_timestamps
579 If non-zero, timestamps are written to the history file, so they can be
580 preserved between sessions. The default value is 0, meaning that
581 timestamps are not saved.
582 The current timestamp format uses the value of \fIhistory_comment_char\fP
583 to delimit timestamp entries in the history file. If that variable does
584 not have a value (the default), timestamps will not be written.
586 .Vb char history_expansion_char
587 The character that introduces a history event. The default is \fB!\fP.
588 Setting this to 0 inhibits history expansion.
590 .Vb char history_subst_char
591 The character that invokes word substitution if found at the start of
592 a line. The default is \fB^\fP.
594 .Vb char history_comment_char
595 During tokenization, if this character is seen as the first character
596 of a word, then it and all subsequent characters up to a newline are
597 ignored, suppressing history expansion for the remainder of the line.
598 This is disabled by default.
600 .Vb "char *" history_word_delimiters
601 The characters that separate tokens for \fBhistory_tokenize()\fP.
602 The default value is \fB"\ \et\en()<>;&|"\fP.
604 .Vb "char *" history_no_expand_chars
605 The list of characters which inhibit history expansion if found immediately
606 following \fBhistory_expansion_char\fP. The default is space, tab, newline,
607 \fB\er\fP, and \fB=\fP.
609 .Vb "char *" history_search_delimiter_chars
610 The list of additional characters which can delimit a history search
611 string, in addition to space, tab, \fI:\fP and \fI?\fP in the case of
612 a substring search. The default is empty.
614 .Vb int history_quotes_inhibit_expansion
615 If non-zero, single-quoted words are not scanned for the history expansion
616 character. The default value is 0.
618 .Vb "rl_linebuf_func_t *" history_inhibit_expansion_function
619 This should be set to the address of a function that takes two arguments:
620 a \fBchar *\fP (\fIstring\fP)
621 and an \fBint\fP index into that string (\fIi\fP).
622 It should return a non-zero value if the history expansion starting at
623 \fIstring[i]\fP should not be performed; zero if the expansion should
625 It is intended for use by applications like \fBbash\fP that use the history
626 expansion character for additional purposes.
627 By default, this variable is set to \fBNULL\fP.
632 Default filename for reading and writing saved history
637 \fIThe Gnu Readline Library\fP, Brian Fox and Chet Ramey
639 \fIThe Gnu History Library\fP, Brian Fox and Chet Ramey
646 Brian Fox, Free Software Foundation
650 Chet Ramey, Case Western Reserve University
654 If you find a bug in the
656 library, you should report it. But first, you should
657 make sure that it really is a bug, and that it appears in the latest
660 library that you have.
662 Once you have determined that a bug actually exists, mail a
663 bug report to \fIbug\-readline\fP@\fIgnu.org\fP.
664 If you have a fix, you are welcome to mail that
665 as well! Suggestions and `philosophical' bug reports may be mailed
666 to \fPbug-readline\fP@\fIgnu.org\fP or posted to the Usenet
670 Comments and bug reports concerning
671 this manual page should be directed to
672 .IR chet@ins.CWRU.Edu .
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