2 .\" MAN PAGE COMMENTS to
5 .\" Information Network Services
6 .\" Case Western Reserve University
7 .\" chet.ramey@case.edu
9 .\" Last Change: Fri Jul 17 09:43:01 EDT 2020
11 .TH HISTORY 3 "2020 July 17" "GNU History 8.1"
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 1989-2020 by the Free Software Foundation, Inc.
44 .if n The GNU History Library is Copyright (C) 1989-2020 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"
52 The history library supports a history expansion feature that
53 is identical to the history expansion in
55 This section describes what syntax features are available.
57 History expansions introduce words from the history list into
58 the input stream, making it easy to repeat commands, insert the
59 arguments to a previous command into the current input line, or
60 fix errors in previous commands quickly.
62 History expansion is usually performed immediately after a complete line
64 It takes place in two parts.
65 The first is to determine which line from the history list
66 to use during substitution.
67 The second is to select portions of that line for inclusion into
69 The line selected from the history is the \fIevent\fP,
70 and the portions of that line that are acted upon are \fIwords\fP.
71 Various \fImodifiers\fP are available to manipulate the selected words.
72 The line is broken into words in the same fashion as \fBbash\fP
73 does when reading input,
74 so that several words that would otherwise be separated
75 are considered one word when surrounded by quotes (see the
76 description of \fBhistory_tokenize()\fP below).
77 History expansions are introduced by the appearance of the
78 history expansion character, which is \^\fB!\fP\^ by default.
79 Only backslash (\^\fB\e\fP\^) and single quotes can quote
80 the history expansion character.
82 An event designator is a reference to a command line entry in the
84 Unless the reference is absolute, events are relative to the current
85 position in the history list.
90 Start a history substitution, except when followed by a
99 Refer to the current command minus
103 Refer to the previous command. This is a synonym for `!\-1'.
106 Refer to the most recent command
107 preceding the current position in the history list
111 .B !?\fIstring\fR\fB[?]\fR
112 Refer to the most recent command
113 preceding the current position in the history list
116 The trailing \fB?\fP may be omitted if
118 is followed immediately by a newline.
119 If \fIstring\fP is missing, the string from the most recent search is used;
120 it is an error if there is no previous search string.
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\d\s+2^\s-2\u\fIstring1\fP\d\s+2^\s-2\u\fIstring2\fP\d\s+2^\s-2\u''
129 (see \fBModifiers\fP below).
132 The entire command line typed so far.
135 Word designators are used to select desired words from the event.
138 separates the event specification from the word designator.
139 It may be omitted if the word designator begins with a
146 Words are numbered from the beginning of the line,
147 with the first word being denoted by 0 (zero).
148 Words are inserted into the current line separated by single spaces.
153 The zeroth word. For the shell, this is the command
160 The first argument. That is, word 1.
163 The last word. This is usually the last argument, but will expand to the
164 zeroth word if there is only one word in the line.
167 The first word matched by the most recent `?\fIstring\fR?' search,
168 if the search string begins with a character that is part of a word.
171 A range of words; `\-\fIy\fR' abbreviates `0\-\fIy\fR'.
174 All of the words but the zeroth. This is a synonym
175 for `\fI1\-$\fP'. It is not an error to use
178 word in the event; the empty string is returned in that case.
181 Abbreviates \fIx\-$\fP.
184 Abbreviates \fIx\-$\fP like \fBx*\fP, but omits the last word.
185 If \fBx\fP is missing, it defaults to 0.
188 If a word designator is supplied without an event specification, the
189 previous command is used as the event.
191 After the optional word designator, there may appear a sequence of
192 one or more of the following modifiers, each preceded by a `:'.
193 These modify, or edit, the word or words selected from the history event.
199 Remove a trailing file name component, leaving only the head.
202 Remove all leading file name components, leaving the tail.
205 Remove a trailing suffix of the form \fI.xxx\fP, leaving the
209 Remove all but the trailing suffix.
212 Print the new command but do not execute it.
215 Quote the substituted words, escaping further substitutions.
218 Quote the substituted words as with
220 but break into words at
223 The \fBq\fP and \fBx\fP modifiers are mutually exclusive; the last one
226 .B s/\fIold\fP/\fInew\fP/
229 for the first occurrence of
232 Any character may be used as the delimiter in place of /.
233 The final delimiter is optional if it is the last character of the
235 The delimiter may be quoted in
239 with a single backslash. If & appears in
243 A single backslash will quote the &.
246 is null, it is set to the last
248 substituted, or, if no previous history substitutions took place,
252 .B !?\fIstring\fR\fB[?]\fR
256 is null, each matching
261 Repeat the previous substitution.
264 Cause changes to be applied over the entire event line. This is
265 used in conjunction with `\fB:s\fP' (e.g., `\fB:gs/\fIold\fP/\fInew\fP/\fR')
266 or `\fB:&\fP'. If used with
267 `\fB:s\fP', any delimiter can be used
268 in place of /, and the final delimiter is optional
269 if it is the last character of the event line.
270 An \fBa\fP may be used as a synonym for \fBg\fP.
273 Apply the following `\fBs\fP' or `\fB&\fP' modifier once to each word
276 .SH "PROGRAMMING WITH HISTORY FUNCTIONS"
277 This section describes how to use the History library in other programs.
278 .SS Introduction to History
279 A programmer using the History library has available functions
280 for remembering lines on a history list, associating arbitrary data
281 with a line, removing lines from the list, searching through the list
282 for a line containing an arbitrary text string, and referencing any line
283 in the list directly. In addition, a history \fIexpansion\fP function
284 is available which provides for a consistent user interface across
287 The user using programs written with the History library has the
288 benefit of a consistent user interface with a set of well-known
289 commands for manipulating the text of previous lines and using that text
290 in new commands. The basic history manipulation commands are
292 the history substitution provided by \fBbash\fP.
294 The programmer can also use the Readline library, which
295 includes some history manipulation by default, and has the added
296 advantage of command line editing.
298 Before declaring any functions using any functionality the History
299 library provides in other code, an application writer should include
301 .FN <readline/history.h>
302 in any file that uses the
303 History library's features. It supplies extern declarations for all
304 of the library's public functions and variables, and declares all of
305 the public data structures.
307 The history list is an array of history entries. A history entry is
310 .Vb "typedef void *" histdata_t;
313 typedef struct _hist_entry {
320 The history list itself might therefore be declared as
322 .Vb "HIST_ENTRY **" the_history_list;
324 The state of the History library is encapsulated into a single structure:
328 * A structure used to pass around the current state of the history.
330 typedef struct _hist_state {
331 HIST_ENTRY **entries; /* Pointer to the entries themselves. */
332 int offset; /* The location pointer within this array. */
333 int length; /* Number of elements within this array. */
334 int size; /* Number of slots allocated to this array. */
339 If the flags member includes \fBHS_STIFLED\fP, the history has been
341 .SH "History Functions"
342 This section describes the calling sequence for the various functions
343 exported by the GNU History library.
344 .SS Initializing History and State Management
345 This section describes functions used to initialize and manage
346 the state of the History library when you want to use the history
347 functions in your program.
349 .Fn1 void using_history void
350 Begin a session in which the history functions might be used. This
351 initializes the interactive variables.
353 .Fn1 "HISTORY_STATE *" history_get_history_state void
354 Return a structure describing the current state of the input history.
356 .Fn1 void history_set_history_state "HISTORY_STATE *state"
357 Set the state of the history list according to \fIstate\fP.
359 .SS History List Management
360 These functions manage individual entries on the history list, or set
361 parameters managing the list itself.
363 .Fn1 void add_history "const char *string"
364 Place \fIstring\fP at the end of the history list. The associated data
365 field (if any) is set to \fBNULL\fP.
366 If the maximum number of history entries has been set using
367 \fBstifle_history()\fP, and the new number of history entries would exceed
368 that maximum, the oldest history entry is removed.
370 .Fn1 void add_history_time "const char *string"
371 Change the time stamp associated with the most recent history entry to
374 .Fn1 "HIST_ENTRY *" remove_history "int which"
375 Remove history entry at offset \fIwhich\fP from the history. The
376 removed element is returned so you can free the line, data,
377 and containing structure.
379 .Fn1 "histdata_t" free_history_entry "HIST_ENTRY *histent"
380 Free the history entry \fIhistent\fP and any history library private
381 data associated with it. Returns the application-specific data
382 so the caller can dispose of it.
384 .Fn3 "HIST_ENTRY *" replace_history_entry "int which" "const char *line" "histdata_t data"
385 Make the history entry at offset \fIwhich\fP have \fIline\fP and \fIdata\fP.
386 This returns the old entry so the caller can dispose of any
387 application-specific data. In the case
388 of an invalid \fIwhich\fP, a \fBNULL\fP pointer is returned.
390 .Fn1 void clear_history "void"
391 Clear the history list by deleting all the entries.
393 .Fn1 void stifle_history "int max"
394 Stifle the history list, remembering only the last \fImax\fP entries.
395 The history list will contain only \fImax\fP entries at a time.
397 .Fn1 int unstifle_history "void"
398 Stop stifling the history. This returns the previously-set
399 maximum number of history entries (as set by \fBstifle_history()\fP).
400 history was stifled. The value is positive if the history was
401 stifled, negative if it wasn't.
403 .Fn1 int history_is_stifled "void"
404 Returns non-zero if the history is stifled, zero if it is not.
406 .SS Information About the History List
408 These functions return information about the entire history list or
409 individual list entries.
411 .Fn1 "HIST_ENTRY **" history_list "void"
412 Return a \fBNULL\fP terminated array of \fIHIST_ENTRY *\fP which is the
413 current input history. Element 0 of this list is the beginning of time.
414 If there is no history, return \fBNULL\fP.
416 .Fn1 int where_history "void"
417 Returns the offset of the current history element.
419 .Fn1 "HIST_ENTRY *" current_history "void"
420 Return the history entry at the current position, as determined by
421 \fBwhere_history()\fP. If there is no entry there, return a \fBNULL\fP
424 .Fn1 "HIST_ENTRY *" history_get "int offset"
425 Return the history entry at position \fIoffset\fP.
426 The range of valid values of \fIoffset\fP starts at \fBhistory_base\fP
427 and ends at \fBhistory_length\fP \- 1.
428 If there is no entry there, or if \fIoffset\fP is outside the valid
429 range, return a \fBNULL\fP pointer.
431 .Fn1 "time_t" history_get_time "HIST_ENTRY *"
432 Return the time stamp associated with the history entry passed as the argument.
434 .Fn1 int history_total_bytes "void"
435 Return the number of bytes that the primary history entries are using.
436 This function returns the sum of the lengths of all the lines in the
439 .SS Moving Around the History List
441 These functions allow the current index into the history list to be
444 .Fn1 int history_set_pos "int pos"
445 Set the current history offset to \fIpos\fP, an absolute index
447 Returns 1 on success, 0 if \fIpos\fP is less than zero or greater
448 than the number of history entries.
450 .Fn1 "HIST_ENTRY *" previous_history "void"
451 Back up the current history offset to the previous history entry, and
452 return a pointer to that entry. If there is no previous entry, return
453 a \fBNULL\fP pointer.
455 .Fn1 "HIST_ENTRY *" next_history "void"
456 If the current history offset refers to a valid history entry,
457 increment the current history offset.
458 If the possibly-incremented history offset refers to a valid history
459 entry, return a pointer to that entry;
460 otherwise, return a \fBNULL\fP pointer.
462 .SS Searching the History List
464 These functions allow searching of the history list for entries containing
465 a specific string. Searching may be performed both forward and backward
466 from the current history position. The search may be \fIanchored\fP,
467 meaning that the string must match at the beginning of the history entry.
469 .Fn2 int history_search "const char *string" "int direction"
470 Search the history for \fIstring\fP, starting at the current history offset.
471 If \fIdirection\fP is less than 0, then the search is through
472 previous entries, otherwise through subsequent entries.
473 If \fIstring\fP is found, then
474 the current history index is set to that history entry, and the value
475 returned is the offset in the line of the entry where
476 \fIstring\fP was found. Otherwise, nothing is changed, and a -1 is
479 .Fn2 int history_search_prefix "const char *string" "int direction"
480 Search the history for \fIstring\fP, starting at the current history
481 offset. The search is anchored: matching lines must begin with
482 \fIstring\fP. If \fIdirection\fP is less than 0, then the search is
483 through previous entries, otherwise through subsequent entries.
484 If \fIstring\fP is found, then the
485 current history index is set to that entry, and the return value is 0.
486 Otherwise, nothing is changed, and a -1 is returned.
488 .Fn3 int history_search_pos "const char *string" "int direction" "int pos"
489 Search for \fIstring\fP in the history list, starting at \fIpos\fP, an
490 absolute index into the list. If \fIdirection\fP is negative, the search
491 proceeds backward from \fIpos\fP, otherwise forward. Returns the absolute
492 index of the history element where \fIstring\fP was found, or -1 otherwise.
494 .SS Managing the History File
495 The History library can read the history from and write it to a file.
496 This section documents the functions for managing a history file.
498 .Fn1 int read_history "const char *filename"
499 Add the contents of \fIfilename\fP to the history list, a line at a time.
500 If \fIfilename\fP is \fBNULL\fP, then read from \fI~/.history\fP.
501 Returns 0 if successful, or \fBerrno\fP if not.
503 .Fn3 int read_history_range "const char *filename" "int from" "int to"
504 Read a range of lines from \fIfilename\fP, adding them to the history list.
505 Start reading at line \fIfrom\fP and end at \fIto\fP.
506 If \fIfrom\fP is zero, start at the beginning. If \fIto\fP is less than
507 \fIfrom\fP, then read until the end of the file. If \fIfilename\fP is
508 \fBNULL\fP, then read from \fI~/.history\fP. Returns 0 if successful,
509 or \fBerrno\fP if not.
511 .Fn1 int write_history "const char *filename"
512 Write the current history to \fIfilename\fP, overwriting \fIfilename\fP
514 If \fIfilename\fP is \fBNULL\fP, then write the history list to \fI~/.history\fP.
515 Returns 0 on success, or \fBerrno\fP on a read or write error.
518 .Fn2 int append_history "int nelements" "const char *filename"
519 Append the last \fInelements\fP of the history list to \fIfilename\fP.
520 If \fIfilename\fP is \fBNULL\fP, then append to \fI~/.history\fP.
521 Returns 0 on success, or \fBerrno\fP on a read or write error.
523 .Fn2 int history_truncate_file "const char *filename" "int nlines"
524 Truncate the history file \fIfilename\fP, leaving only the last
526 If \fIfilename\fP is \fBNULL\fP, then \fI~/.history\fP is truncated.
527 Returns 0 on success, or \fBerrno\fP on failure.
529 .SS History Expansion
531 These functions implement history expansion.
533 .Fn2 int history_expand "char *string" "char **output"
534 Expand \fIstring\fP, placing the result into \fIoutput\fP, a pointer
535 to a string. Returns:
540 If no expansions took place (or, if the only change in
541 the text was the removal of escape characters preceding the history expansion
545 if expansions did take place;
548 if there was an error in expansion;
551 if the returned line should be displayed, but not executed,
552 as with the \fB:p\fP modifier.
555 If an error occurred in expansion, then \fIoutput\fP contains a descriptive
558 .Fn3 "char *" get_history_event "const char *string" "int *cindex" "int qchar"
559 Returns the text of the history event beginning at \fIstring\fP +
560 \fI*cindex\fP. \fI*cindex\fP is modified to point to after the event
561 specifier. At function entry, \fIcindex\fP points to the index into
562 \fIstring\fP where the history event specification begins. \fIqchar\fP
563 is a character that is allowed to end the event specification in addition
564 to the ``normal'' terminating characters.
566 .Fn1 "char **" history_tokenize "const char *string"
567 Return an array of tokens parsed out of \fIstring\fP, much as the
569 The tokens are split on the characters in the
570 \fBhistory_word_delimiters\fP variable,
571 and shell quoting conventions are obeyed.
573 .Fn3 "char *" history_arg_extract "int first" "int last" "const char *string"
574 Extract a string segment consisting of the \fIfirst\fP through \fIlast\fP
575 arguments present in \fIstring\fP. Arguments are split using
576 \fBhistory_tokenize()\fP.
578 .SS History Variables
580 This section describes the externally-visible variables exported by
581 the GNU History Library.
584 The logical offset of the first entry in the history list.
586 .Vb int history_length
587 The number of entries currently stored in the history list.
589 .Vb int history_max_entries
590 The maximum number of history entries. This must be changed using
591 \fBstifle_history()\fP.
593 .Vb int history_write_timestamps
594 If non-zero, timestamps are written to the history file, so they can be
595 preserved between sessions. The default value is 0, meaning that
596 timestamps are not saved.
597 The current timestamp format uses the value of \fIhistory_comment_char\fP
598 to delimit timestamp entries in the history file. If that variable does
599 not have a value (the default), timestamps will not be written.
601 .Vb char history_expansion_char
602 The character that introduces a history event. The default is \fB!\fP.
603 Setting this to 0 inhibits history expansion.
605 .Vb char history_subst_char
606 The character that invokes word substitution if found at the start of
607 a line. The default is \fB^\fP.
609 .Vb char history_comment_char
610 During tokenization, if this character is seen as the first character
611 of a word, then it and all subsequent characters up to a newline are
612 ignored, suppressing history expansion for the remainder of the line.
613 This is disabled by default.
615 .Vb "char *" history_word_delimiters
616 The characters that separate tokens for \fBhistory_tokenize()\fP.
617 The default value is \fB"\ \et\en()<>;&|"\fP.
619 .Vb "char *" history_no_expand_chars
620 The list of characters which inhibit history expansion if found immediately
621 following \fBhistory_expansion_char\fP. The default is space, tab, newline,
622 \fB\er\fP, and \fB=\fP.
624 .Vb "char *" history_search_delimiter_chars
625 The list of additional characters which can delimit a history search
626 string, in addition to space, tab, \fI:\fP and \fI?\fP in the case of
627 a substring search. The default is empty.
629 .Vb int history_quotes_inhibit_expansion
630 If non-zero, double-quoted words are not scanned for the history expansion
631 character or the history comment character. The default value is 0.
633 .Vb "rl_linebuf_func_t *" history_inhibit_expansion_function
634 This should be set to the address of a function that takes two arguments:
635 a \fBchar *\fP (\fIstring\fP)
636 and an \fBint\fP index into that string (\fIi\fP).
637 It should return a non-zero value if the history expansion starting at
638 \fIstring[i]\fP should not be performed; zero if the expansion should
640 It is intended for use by applications like \fBbash\fP that use the history
641 expansion character for additional purposes.
642 By default, this variable is set to \fBNULL\fP.
647 Default filename for reading and writing saved history
652 \fIThe Gnu Readline Library\fP, Brian Fox and Chet Ramey
654 \fIThe Gnu History Library\fP, Brian Fox and Chet Ramey
661 Brian Fox, Free Software Foundation
665 Chet Ramey, Case Western Reserve University
669 If you find a bug in the
671 library, you should report it. But first, you should
672 make sure that it really is a bug, and that it appears in the latest
675 library that you have.
677 Once you have determined that a bug actually exists, mail a
678 bug report to \fIbug\-readline\fP@\fIgnu.org\fP.
679 If you have a fix, you are welcome to mail that
680 as well! Suggestions and `philosophical' bug reports may be mailed
681 to \fPbug-readline\fP@\fIgnu.org\fP or posted to the Usenet
685 Comments and bug reports concerning
686 this manual page should be directed to
687 .IR chet.ramey@case.edu .
projects / binutils-gdb.git / blob