aboutsummaryrefslogtreecommitdiff
path: root/readline/doc/history.3
blob: ed0cb9f84e0499d89735ea49e44a20389402d228 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
.\"
.\" MAN PAGE COMMENTS to
.\"
.\"	Chet Ramey
.\"	Information Network Services
.\"	Case Western Reserve University
.\"	chet@ins.CWRU.Edu
.\"
.\"	Last Change: Thu Jan 31 16:08:07 EST 2002
.\"
.TH HISTORY 3 "2002 January 31" "GNU History 4.3"
.\"
.\" File Name macro.  This used to be `.PN', for Path Name,
.\" but Sun doesn't seem to like that very much.
.\"
.de FN
\fI\|\\$1\|\fP
..
.ds lp \fR\|(\fP
.ds rp \fR\|)\fP
.\" FnN return-value fun-name N arguments
.de Fn1
\fI\\$1\fP \fB\\$2\fP \\*(lp\fI\\$3\fP\\*(rp
.br
..
.de Fn2
.if t \fI\\$1\fP \fB\\$2\fP \\*(lp\fI\\$3,\|\\$4\fP\\*(rp
.if n \fI\\$1\fP \fB\\$2\fP \\*(lp\fI\\$3, \\$4\fP\\*(rp
.br
..
.de Fn3
.if t \fI\\$1\fP \fB\\$2\fP \\*(lp\fI\\$3,\|\\$4,\|\\$5\fP\|\\*(rp
.if n \fI\\$1\fP \fB\\$2\fP \\*(lp\fI\\$3, \\$4, \\$5\fP\\*(rp
.br
..
.de Vb
\fI\\$1\fP \fB\\$2\fP
.br
..
.SH NAME
history \- GNU History Library
.SH COPYRIGHT
.if t The GNU History Library is Copyright \(co 1989-2002 by the Free Software Foundation, Inc.
.if n The GNU History Library is Copyright (C) 1989-2002 by the Free Software Foundation, Inc.
.SH DESCRIPTION
Many programs read input from the user a line at a time.  The GNU
History library is able to keep track of those lines, associate arbitrary
data with each line, and utilize information from previous lines in
composing new ones. 
.PP
.SH "HISTORY EXPANSION"
.PP
The history library supports a history expansion feature that
is identical to the history expansion in
.BR bash.
This section describes what syntax features are available.
.PP
History expansions introduce words from the history list into
the input stream, making it easy to repeat commands, insert the
arguments to a previous command into the current input line, or
fix errors in previous commands quickly.
.PP
History expansion is usually performed immediately after a complete line
is read.
It takes place in two parts.
The first is to determine which line from the history list
to use during substitution.
The second is to select portions of that line for inclusion into
the current one.
The line selected from the history is the \fIevent\fP,
and the portions of that line that are acted upon are \fIwords\fP.
Various \fImodifiers\fP are available to manipulate the selected words.
The line is broken into words in the same fashion as \fBbash\fP
does when reading input,
so that several words that would otherwise be separated 
are considered one word when surrounded by quotes (see the
description of \fBhistory_tokenize()\fP below).
History expansions are introduced by the appearance of the
history expansion character, which is \^\fB!\fP\^ by default.
Only backslash (\^\fB\e\fP\^) and single quotes can quote
the history expansion character.
.SS Event Designators
.PP
An event designator is a reference to a command line entry in the
history list.
.PP
.PD 0
.TP
.B !
Start a history substitution, except when followed by a
.BR blank ,
newline, = or (.
.TP
.B !\fIn\fR
Refer to command line
.IR n .
.TP
.B !\-\fIn\fR
Refer to the current command line minus
.IR n .
.TP
.B !!
Refer to the previous command.  This is a synonym for `!\-1'.
.TP
.B !\fIstring\fR
Refer to the most recent command starting with 
.IR string .
.TP
.B !?\fIstring\fR\fB[?]\fR
Refer to the most recent command containing
.IR string .
The trailing \fB?\fP may be omitted if
.I string
is followed immediately by a newline.
.TP
.B \d\s+2^\s-2\u\fIstring1\fP\d\s+2^\s-2\u\fIstring2\fP\d\s+2^\s-2\u
Quick substitution.  Repeat the last command, replacing
.I string1
with
.IR string2 .
Equivalent to
``!!:s/\fIstring1\fP/\fIstring2\fP/''
(see \fBModifiers\fP below).
.TP
.B !#
The entire command line typed so far.
.PD
.SS Word Designators
.PP
Word designators are used to select desired words from the event.
A 
.B :
separates the event specification from the word designator.
It may be omitted if the word designator begins with a
.BR ^ ,
.BR $ ,
.BR * ,
.BR \- ,
or
.BR % .
Words are numbered from the beginning of the line,
with the first word being denoted by 0 (zero).
Words are inserted into the current line separated by single spaces.
.PP
.PD 0
.TP
.B 0 (zero)
The zeroth word.  For the shell, this is the command
word.
.TP
.I n
The \fIn\fRth word.
.TP
.B ^
The first argument.  That is, word 1.
.TP
.B $
The last argument.
.TP
.B %
The word matched by the most recent `?\fIstring\fR?' search.
.TP
.I x\fB\-\fPy
A range of words; `\-\fIy\fR' abbreviates `0\-\fIy\fR'.
.TP
.B *
All of the words but the zeroth.  This is a synonym
for `\fI1\-$\fP'.  It is not an error to use
.B *
if there is just one
word in the event; the empty string is returned in that case.
.TP
.B x*
Abbreviates \fIx\-$\fP.
.TP
.B x\-
Abbreviates \fIx\-$\fP like \fBx*\fP, but omits the last word.
.PD
.PP
If a word designator is supplied without an event specification, the
previous command is used as the event.
.SS Modifiers
.PP
After the optional word designator, there may appear a sequence of
one or more of the following modifiers, each preceded by a `:'.
.PP
.PD 0
.PP
.TP
.B h
Remove a trailing file name component, leaving only the head.
.TP
.B t
Remove all leading file name components, leaving the tail.
.TP
.B r
Remove a trailing suffix of the form \fI.xxx\fP, leaving the
basename.
.TP
.B e
Remove all but the trailing suffix.
.TP
.B p
Print the new command but do not execute it.
.TP
.B q
Quote the substituted words, escaping further substitutions.
.TP
.B x
Quote the substituted words as with
.BR q ,
but break into words at
.B blanks
and newlines.
.TP
.B s/\fIold\fP/\fInew\fP/
Substitute
.I new
for the first occurrence of
.I old
in the event line.  Any delimiter can be used in place of /.  The
final delimiter is optional if it is the last character of the
event line.  The delimiter may be quoted in
.I old
and
.I new
with a single backslash.  If & appears in
.IR new ,
it is replaced by
.IR old .
A single backslash will quote the &.  If
.I old
is null, it is set to the last
.I old
substituted, or, if no previous history substitutions took place,
the last
.I string
in a
.B !?\fIstring\fR\fB[?]\fR
search.
.TP
.B &
Repeat the previous substitution.
.TP
.B g
Cause changes to be applied over the entire event line.  This is
used in conjunction with `\fB:s\fP' (e.g., `\fB:gs/\fIold\fP/\fInew\fP/\fR')
or `\fB:&\fP'.  If used with
`\fB:s\fP', any delimiter can be used
in place of /, and the final delimiter is optional
if it is the last character of the event line.
.PD
.SH "PROGRAMMING WITH HISTORY FUNCTIONS"
This section describes how to use the History library in other programs.
.SS Introduction to History
.PP
The programmer using the History library has available functions
for remembering lines on a history list, associating arbitrary data
with a line, removing lines from the list, searching through the list
for a line containing an arbitrary text string, and referencing any line
in the list directly.  In addition, a history \fIexpansion\fP function
is available which provides for a consistent user interface across
different programs.
.PP
The user using programs written with the History library has the
benefit of a consistent user interface with a set of well-known
commands for manipulating the text of previous lines and using that text
in new commands.  The basic history manipulation commands are
identical to
the history substitution provided by \fBbash\fP.
.PP
If the programmer desires, he can use the Readline library, which
includes some history manipulation by default, and has the added
advantage of command line editing.
.PP
Before declaring any functions using any functionality the History
library provides in other code, an application writer should include
the file
.FN <readline/history.h>
in any file that uses the
History library's features.  It supplies extern declarations for all
of the library's public functions and variables, and declares all of
the public data structures.

.SS History Storage
.PP
The history list is an array of history entries.  A history entry is
declared as follows:
.PP
.Vb "typedef void *" histdata_t;
.PP
.nf
typedef struct _hist_entry {
  char *line;
  histdata_t data;
} HIST_ENTRY;
.fi
.PP
The history list itself might therefore be declared as
.PP
.Vb "HIST_ENTRY **" the_history_list;
.PP
The state of the History library is encapsulated into a single structure:
.PP
.nf
/*
 * A structure used to pass around the current state of the history.
 */
typedef struct _hist_state {
  HIST_ENTRY **entries; /* Pointer to the entries themselves. */
  int offset;           /* The location pointer within this array. */
  int length;           /* Number of elements within this array. */
  int size;             /* Number of slots allocated to this array. */
  int flags;
} HISTORY_STATE;
.fi
.PP
If the flags member includes \fBHS_STIFLED\fP, the history has been
stifled.
.SH "History Functions"
.PP
This section describes the calling sequence for the various functions
exported by the GNU History library.
.SS Initializing History and State Management
This section describes functions used to initialize and manage
the state of the History library when you want to use the history
functions in your program.

.Fn1 void using_history void
Begin a session in which the history functions might be used.  This
initializes the interactive variables.

.Fn1 "HISTORY_STATE *" history_get_history_state void
Return a structure describing the current state of the input history.

.Fn1 void history_set_history_state "HISTORY_STATE *state"
Set the state of the history list according to \fIstate\fP.

.SS History List Management

These functions manage individual entries on the history list, or set
parameters managing the list itself.

.Fn1 void add_history "const char *string"
Place \fIstring\fP at the end of the history list.  The associated data
field (if any) is set to \fBNULL\fP.

.Fn1 "HIST_ENTRY *" remove_history "int which"
Remove history entry at offset \fIwhich\fP from the history.  The
removed element is returned so you can free the line, data,
and containing structure.

.Fn3 "HIST_ENTRY *" replace_history_entry "int which" "const char *line" "histdata_t data"
Make the history entry at offset \fIwhich\fP have \fIline\fP and \fIdata\fP.
This returns the old entry so you can dispose of the data.  In the case
of an invalid \fIwhich\fP, a \fBNULL\fP pointer is returned.

.Fn1 void clear_history "void"
Clear the history list by deleting all the entries.

.Fn1 void stifle_history "int max"
Stifle the history list, remembering only the last \fImax\fP entries.

.Fn1 int unstifle_history "void"
Stop stifling the history.  This returns the previously-set
maximum number of history entries (as set by \fBstifle_history()\fP).
history was stifled.  The value is positive if the history was
stifled, negative if it wasn't.

.Fn1 int history_is_stifled "void"
Returns non-zero if the history is stifled, zero if it is not.

.SS Information About the History List

These functions return information about the entire history list or
individual list entries.

.Fn1 "HIST_ENTRY **" history_list "void"
Return a \fBNULL\fP terminated array of \fIHIST_ENTRY *\fP which is the
current input history.  Element 0 of this list is the beginning of time.
If there is no history, return \fBNULL\fP.

.Fn1 int where_history "void"
Returns the offset of the current history element.

.Fn1 "HIST_ENTRY *" current_history "void"
Return the history entry at the current position, as determined by
\fBwhere_history()\fP.  If there is no entry there, return a \fBNULL\fP
pointer.

.Fn1 "HIST_ENTRY *" history_get "int offset"
Return the history entry at position \fIoffset\fP, starting from
\fBhistory_base\fP.
If there is no entry there, or if \fIoffset\fP
is greater than the history length, return a \fBNULL\fP pointer.

.Fn1 int history_total_bytes "void"
Return the number of bytes that the primary history entries are using.
This function returns the sum of the lengths of all the lines in the
history.

.SS Moving Around the History List

These functions allow the current index into the history list to be
set or changed.

.Fn1 int history_set_pos "int pos"
Set the current history offset to \fIpos\fP, an absolute index
into the list.
Returns 1 on success, 0 if \fIpos\fP is less than zero or greater
than the number of history entries.

.Fn1 "HIST_ENTRY *" previous_history "void"
Back up the current history offset to the previous history entry, and
return a pointer to that entry.  If there is no previous entry, return
a \fBNULL\fP pointer.

.Fn1 "HIST_ENTRY *" next_history "void"
Move the current history offset forward to the next history entry, and
return the a pointer to that entry.  If there is no next entry, return
a \fBNULL\fP pointer.

.SS Searching the History List

These functions allow searching of the history list for entries containing
a specific string.  Searching may be performed both forward and backward
from the current history position.  The search may be \fIanchored\fP,
meaning that the string must match at the beginning of the history entry.

.Fn2 int history_search "const char *string" "int direction"
Search the history for \fIstring\fP, starting at the current history offset.
If \fIdirection\fP is less than 0, then the search is through
previous entries, otherwise through subsequent entries.
If \fIstring\fP is found, then
the current history index is set to that history entry, and the value
returned is the offset in the line of the entry where
\fIstring\fP was found.  Otherwise, nothing is changed, and a -1 is
returned.

.Fn2 int history_search_prefix "const char *string" "int direction"
Search the history for \fIstring\fP, starting at the current history
offset.  The search is anchored: matching lines must begin with
\fIstring\fP.  If \fIdirection\fP is less than 0, then the search is
through previous entries, otherwise through subsequent entries.
If \fIstring\fP is found, then the
current history index is set to that entry, and the return value is 0. 
Otherwise, nothing is changed, and a -1 is returned. 

.Fn3 int history_search_pos "const char *string" "int direction" "int pos"
Search for \fIstring\fP in the history list, starting at \fIpos\fP, an
absolute index into the list.  If \fIdirection\fP is negative, the search
proceeds backward from \fIpos\fP, otherwise forward.  Returns the absolute
index of the history element where \fIstring\fP was found, or -1 otherwise.

.SS Managing the History File
The History library can read the history from and write it to a file.
This section documents the functions for managing a history file.

.Fn1 int read_history "const char *filename"
Add the contents of \fIfilename\fP to the history list, a line at a time.
If \fIfilename\fP is \fBNULL\fP, then read from \fI~/.history\fP.
Returns 0 if successful, or \fBerrno\fP if not.

.Fn3 int read_history_range "const char *filename" "int from" "int to"
Read a range of lines from \fIfilename\fP, adding them to the history list.
Start reading at line \fIfrom\fP and end at \fIto\fP.
If \fIfrom\fP is zero, start at the beginning.  If \fIto\fP is less than
\fIfrom\fP, then read until the end of the file.  If \fIfilename\fP is
\fBNULL\fP, then read from \fI~/.history\fP.  Returns 0 if successful,
or \fBerrno\fP if not.

.Fn1 int write_history "const char *filename"
Write the current history to \fIfilename\fP, overwriting \fIfilename\fP
if necessary.
If \fIfilename\fP is \fBNULL\fP, then write the history list to \fI~/.history\fP.
Returns 0 on success, or \fBerrno\fP on a read or write error.


.Fn2 int append_history "int nelements" "const char *filename"
Append the last \fInelements\fP of the history list to \fIfilename\fP.
If \fIfilename\fP is \fBNULL\fP, then append to \fI~/.history\fP.
Returns 0 on success, or \fBerrno\fP on a read or write error.

.Fn2 int history_truncate_file "const char *filename" "int nlines"
Truncate the history file \fIfilename\fP, leaving only the last
\fInlines\fP lines.
If \fIfilename\fP is \fBNULL\fP, then \fI~/.history\fP is truncated.
Returns 0 on success, or \fBerrno\fP on failure.

.SS History Expansion

These functions implement history expansion.

.Fn2 int history_expand "char *string" "char **output"
Expand \fIstring\fP, placing the result into \fIoutput\fP, a pointer
to a string.  Returns:
.RS
.PD 0
.TP
0
If no expansions took place (or, if the only change in
the text was the removal of escape characters preceding the history expansion
character);
.TP
1
if expansions did take place;
.TP
-1
if there was an error in expansion;
.TP
2
if the returned line should be displayed, but not executed,
as with the \fB:p\fP modifier.
.PD
.RE
If an error ocurred in expansion, then \fIoutput\fP contains a descriptive
error message.

.Fn3 "char *" get_history_event "const char *string" "int *cindex" "int qchar"
Returns the text of the history event beginning at \fIstring\fP +
\fI*cindex\fP.  \fI*cindex\fP is modified to point to after the event
specifier.  At function entry, \fIcindex\fP points to the index into
\fIstring\fP where the history event specification begins.  \fIqchar\fP
is a character that is allowed to end the event specification in addition
to the ``normal'' terminating characters.

.Fn1 "char **" history_tokenize "const char *string"
Return an array of tokens parsed out of \fIstring\fP, much as the
shell might.
The tokens are split on the characters in the
\fBhistory_word_delimiters\fP variable,
and shell quoting conventions are obeyed.

.Fn3 "char *" history_arg_extract "int first" "int last" "const char *string"
Extract a string segment consisting of the \fIfirst\fP through \fIlast\fP
arguments present in \fIstring\fP.  Arguments are split using
\fBhistory_tokenize()\fP.

.SS History Variables

This section describes the externally-visible variables exported by
the GNU History Library.

.Vb int history_base
The logical offset of the first entry in the history list.

.Vb int history_length
The number of entries currently stored in the history list.

.Vb int history_max_entries
The maximum number of history entries.  This must be changed using
\fBstifle_history()\fP.

.Vb char history_expansion_char
The character that introduces a history event.  The default is \fB!\fP.
Setting this to 0 inhibits history expansion.

.Vb char history_subst_char
The character that invokes word substitution if found at the start of
a line.  The default is \fB^\fP.

.Vb char history_comment_char
During tokenization, if this character is seen as the first character
of a word, then it and all subsequent characters up to a newline are
ignored, suppressing history expansion for the remainder of the line.
This is disabled by default.

.Vb "char *" history_word_delimiters
The characters that separate tokens for \fBhistory_tokenize()\fP.
The default value is \fB"\ \et\en()<>;&|"\fP.

.Vb "char *" history_no_expand_chars
The list of characters which inhibit history expansion if found immediately
following \fBhistory_expansion_char\fP.  The default is space, tab, newline,
\fB\er\fP, and \fB=\fP.

.Vb "char *" history_search_delimiter_chars
The list of additional characters which can delimit a history search
string, in addition to space, tab, \fI:\fP and \fI?\fP in the case of
a substring search.  The default is empty.

.Vb int history_quotes_inhibit_expansion
If non-zero, single-quoted words are not scanned for the history expansion
character.  The default value is 0.

.Vb "rl_linebuf_func_t *" history_inhibit_expansion_function
This should be set to the address of a function that takes two arguments:
a \fBchar *\fP (\fIstring\fP)
and an \fBint\fP index into that string (\fIi\fP).
It should return a non-zero value if the history expansion starting at
\fIstring[i]\fP should not be performed; zero if the expansion should
be done.
It is intended for use by applications like \fBbash\fP that use the history
expansion character for additional purposes.
By default, this variable is set to \fBNULL\fP.
.SH FILES
.PD 0 
.TP
.FN ~/.history
Default filename for reading and writing saved history
.PD
.SH "SEE ALSO"
.PD 0
.TP
\fIThe Gnu Readline Library\fP, Brian Fox and Chet Ramey
.TP
\fIThe Gnu History Library\fP, Brian Fox and Chet Ramey
.TP
\fIbash\fP(1)
.TP
\fIreadline\fP(3)
.PD
.SH AUTHORS
Brian Fox, Free Software Foundation
.br
bfox@gnu.org
.PP
Chet Ramey, Case Western Reserve University
.br
chet@ins.CWRU.Edu
.SH BUG REPORTS
If you find a bug in the
.B history
library, you should report it.  But first, you should
make sure that it really is a bug, and that it appears in the latest
version of the
.B history
library that you have.
.PP
Once you have determined that a bug actually exists, mail a
bug report to \fIbug\-readline\fP@\fIgnu.org\fP.
If you have a fix, you are welcome to mail that
as well!  Suggestions and `philosophical' bug reports may be mailed
to \fPbug-readline\fP@\fIgnu.org\fP or posted to the Usenet
newsgroup
.BR gnu.bash.bug .
.PP
Comments and bug reports concerning
this manual page should be directed to
.IR chet@ins.CWRU.Edu .