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1 \input texinfo @c -*-texinfo-*-
2 @comment %**start of header
3 @setfilename info.info
4 @settitle Info
5 @syncodeindex fn cp
6 @syncodeindex vr cp
7 @syncodeindex ky cp
8 @comment %**end of header
9 @comment $Id: info.texi,v 1.20 2001/05/03 14:02:33 karl Exp $
10
11 @dircategory Texinfo documentation system
12 @direntry
13 * Info: (info). Documentation browsing system.
14 @end direntry
15
16 @ifinfo
17 This file describes how to use Info, the on-line, menu-driven GNU
18 documentation system.
19
20 Copyright (C) 1989, 92, 96, 97, 98, 99, 2000, 2001
21 Free Software Foundation, Inc.
22
23
24 Permission is granted to copy, distribute and/or modify this document
25 under the terms of the GNU Free Documentation License, Version 1.1 or
26 any later version published by the Free Software Foundation; with no
27 Invariant Sections, with the Front-Cover texts being ``A GNU
28 Manual'', and with the Back-Cover Texts as in (a) below. A copy of the
29 license is included in the section entitled ``GNU Free Documentation
30 License'' in the Emacs manual.
31
32 (a) The FSF's Back-Cover Text is: ``You have freedom to copy and modify
33 this GNU Manual, like GNU software. Copies published by the Free
34 Software Foundation raise funds for GNU development.''
35
36 This document is part of a collection distributed under the GNU Free
37 Documentation License. If you want to distribute this document
38 separately from the collection, you can do so by adding a copy of the
39 license to the document, as described in section 6 of the license.
40 @end ifinfo
41
42 @titlepage
43 @title Info
44 @subtitle The online, hyper-text GNU documentation system
45 @author Brian Fox
46 @author and the GNU Texinfo community
47 @page
48 @vskip 0pt plus 1filll
49 Copyright @copyright{} 1989, 92, 93, 96, 97, 98, 99, 2000, 2001
50 Free Software Foundation, Inc.
51 @sp 2
52 Published by the Free Software Foundation @*
53 59 Temple Place - Suite 330 @*
54 Boston, MA 02111-1307, USA.
55
56 Permission is granted to copy, distribute and/or modify this document
57 under the terms of the GNU Free Documentation License, Version 1.1 or
58 any later version published by the Free Software Foundation; with no
59 Invariant Sections, with the Front-Cover texts being ``A GNU
60 Manual'', and with the Back-Cover Texts as in (a) below. A copy of the
61 license is included in the section entitled ``GNU Free Documentation
62 License'' in the Emacs manual.
63
64 (a) The FSF's Back-Cover Text is: ``You have freedom to copy and modify
65 this GNU Manual, like GNU software. Copies published by the Free
66 Software Foundation raise funds for GNU development.''
67
68 This document is part of a collection distributed under the GNU Free
69 Documentation License. If you want to distribute this document
70 separately from the collection, you can do so by adding a copy of the
71 license to the document, as described in section 6 of the license.
72 @end titlepage
73
74 @ifnottex
75 @node Top
76 @top Info: An Introduction
77
78 Info is a program for reading documentation, which you are using now.
79
80 @ifinfo
81 If you are new to Info and want to learn how to use it, type the
82 command @kbd{h} now. It brings you to a programmed instruction
83 sequence.
84
85 To learn advanced Info commands, type @kbd{n} twice. This brings you to
86 @cite{Info for Experts}, skipping over the `Getting Started' chapter.
87 @end ifinfo
88 @end ifnottex
89
90 @menu
91 * Getting Started:: Getting started using an Info reader.
92 * Advanced Info:: Advanced commands within Info.
93 * Creating an Info File:: How to make your own Info file.
94 * Index:: An index of topics, commands, and variables.
95 @end menu
96
97 @node Getting Started, Advanced Info, Top, Top
98 @comment node-name, next, previous, up
99 @chapter Getting Started
100
101 This first part of the Info manual describes how to get around inside
102 of Info. The second part of the manual describes various advanced
103 Info commands, and how to write an Info as distinct from a Texinfo
104 file. The third part briefly explains how to generate Info files from
105 Texinfo files.
106
107 @ifnotinfo
108 This manual is primarily designed for browsing with an Info reader
109 program on a computer, so that you can try Info commands while reading
110 about them. Reading it on paper or with an HTML browser is less
111 effective, since you must take it on faith that the commands described
112 really do what the manual says. By all means go through this manual
113 now that you have it; but please try going through the on-line version
114 as well.
115
116 @cindex Info reader, how to invoke
117 @cindex entering Info
118 There are two ways of looking at the online version of this manual:
119
120 @enumerate
121 @item
122 Type @code{info} at your shell's command line. This approach uses a
123 stand-alone program designed just to read Info files.
124
125 @item
126 Type @code{emacs} at the command line; then type @kbd{C-h i}
127 (@kbd{Control-h}, followed by @kbd{i}). This approach uses the Info
128 mode of the Emacs program, an editor with many other capabilities.
129 @end enumerate
130
131 In either case, then type @kbd{mInfo} (just the letters), followed by
132 @key{RET}---the ``Return'' or ``Enter'' key. At this point, you should
133 be ready to follow the instructions in this manual as you read them on
134 the screen.
135 @c FIXME! (pesch@cygnus.com, 14 dec 1992)
136 @c Is it worth worrying about what-if the beginner goes to somebody
137 @c else's Emacs session, which already has an Info running in the middle
138 @c of something---in which case these simple instructions won't work?
139 @end ifnotinfo
140
141 @menu
142 * Help-Small-Screen:: Starting Info on a Small Screen
143 * Help:: How to use Info
144 * Help-P:: Returning to the Previous node
145 * Help-^L:: The Space, Rubout, B and ^L commands.
146 * Help-M:: Menus
147 * Help-Adv:: Some advanced Info commands
148 * Help-Q:: Quitting Info
149 @end menu
150
151 @node Help-Small-Screen
152 @section Starting Info on a Small Screen
153
154 @ifnotinfo
155 (In Info, you only see this section if your terminal has a small
156 number of lines; most readers pass by it without seeing it.)
157 @end ifnotinfo
158
159 @cindex small screen, moving around
160 Since your terminal has a relatively small number of lines on its
161 screen, it is necessary to give you special advice at the beginning.
162
163 If you see the text @samp{--All----} near the bottom right corner
164 of the screen, it means the entire text you are looking at fits on the
165 screen. If you see @samp{--Top----} instead, it means that there is
166 more text below that does not fit. To move forward through the text
167 and see another screen full, press @key{SPC}, the Space bar. To move
168 back up, press the key labeled @samp{Backspace} or @samp{DEL} (on some
169 keyboards, this key might be labeled @samp{Delete}).
170
171 @ifinfo
172 Here are 40 lines of junk, so you can try @key{SPC} and @key{DEL} and
173 see what they do. At the end are instructions of what you should do
174 next.
175
176 @format
177 This is line 20
178 This is line 21
179 This is line 22
180 This is line 23
181 This is line 24
182 This is line 25
183 This is line 26
184 This is line 27
185 This is line 28
186 This is line 29
187 This is line 30
188 This is line 31
189 This is line 32
190 This is line 33
191 This is line 34
192 This is line 35
193 This is line 36
194 This is line 37
195 This is line 38
196 This is line 39
197 This is line 40
198 This is line 41
199 This is line 42
200 This is line 43
201 This is line 44
202 This is line 45
203 This is line 46
204 This is line 47
205 This is line 48
206 This is line 49
207 This is line 50
208 This is line 51
209 This is line 52
210 This is line 53
211 This is line 54
212 This is line 55
213 This is line 56
214 This is line 57
215 This is line 58
216 This is line 59
217 @end format
218
219 If you have managed to get here, go back to the beginning with
220 @kbd{DEL} (or @key{BACKSPACE}), and come back here again, then you
221 understand the about the @samp{Space} and @samp{Backspace} keys. So
222 now type an @kbd{n} ---just one character; don't type the quotes and
223 don't type the Return key afterward--- to get to the normal start of
224 the course.
225 @end ifinfo
226
227 @node Help, Help-P, Help-Small-Screen, Getting Started
228 @comment node-name, next, previous, up
229 @section How to use Info
230
231 You are talking to the program Info, for reading documentation.
232
233 @cindex node, in Info documents
234 Right now you are looking at one @dfn{Node} of Information.
235 A node contains text describing a specific topic at a specific
236 level of detail. This node's topic is ``how to use Info''. The mode
237 line says that this is node @samp{Help} in the file @file{info}.
238
239 @cindex header of Info node
240 The top line of a node is its @dfn{header}. This node's header (look at
241 it now) says that the @samp{Next} node after this one is the node
242 called @samp{Help-P}. An advanced Info command lets you go to any node
243 whose name you know. In the stand-alone Info reader program, the
244 header line shows the names of this node and the info file as well.
245 In Emacs, the header line is displayed in a special typeface, and it
246 doesn't scroll off the screen when you scroll the display. The names
247 of this node and of its Info file are omitted by Emacs from the header
248 line.
249
250 Besides a @samp{Next}, a node can have a @samp{Previous} or an
251 @samp{Up} links, or both. As you can see, this node has all of these
252 links.
253
254 @kindex n @r{(Info mode)}
255 Now it is time to move on to the @samp{Next} node, named @samp{Help-P}.
256
257 @format
258 >> Type @kbd{n} to move there. Type just one character;
259 do not type the quotes and do not type a @key{RET} afterward.
260 @end format
261
262 @noindent
263 @samp{>>} in the margin means it is really time to try a command.
264
265 @format
266 >> If you have a mouse, and if you already practiced typing @kbd{n}
267 to get to the next node, click now with the right mouse button on
268 the @samp{Next} link to do the same ``the mouse way''.
269 @end format
270
271 @node Help-P, Help-^L, Help, Getting Started
272 @comment node-name, next, previous, up
273 @section Returning to the Previous node
274
275 @kindex p @r{(Info mode)}
276 This node is called @samp{Help-P}. The @samp{Previous} node, as you see,
277 is @samp{Help}, which is the one you just came from using the @kbd{n}
278 command. Another @kbd{n} command now would take you to the next
279 node, @samp{Help-^L}. In Emacs, @kbd{n} runs the Emacs command
280 @code{Info-next}, and @kbd{p} runs @code{Info-prev}.
281
282 @format
283 >> But do not type @kbd{n} yet. First, try the @kbd{p} command,
284 or click the mouse on the @samp{Prev} link, which takes you to the
285 @samp{Previous} node. When you get there, you can do an @kbd{n}
286 again to return here.
287 @end format
288
289 If you read this in Emacs, you will see an @samp{Info} item in the
290 menu bar, close to its right edge. Clicking your mouse on the
291 @samp{Info} menu-bar item opens a menu of commands which include
292 @samp{Next} and @samp{Prev} (and also some others which you didn't yet
293 learn about).
294
295 This all probably seems insultingly simple so far, but @emph{do not} be
296 led into skimming. Things will get more complicated soon. Also,
297 do not try a new command until you are told it is time to. Otherwise,
298 you may make Info skip past an important warning that was coming up.
299
300 @format
301 >> Now do an @kbd{n}, or click the mouse on the @samp{Next} link, to
302 get to the node @samp{Help-^L} and learn more.
303 @end format
304
305 @node Help-^L, Help-M, Help-P, Getting Started
306 @comment node-name, next, previous, up
307 @section The Space, DEL, B and ^L commands.
308
309 This node's mode line tells you that you are now at node @samp{Help-^L},
310 and the header line tells you that @kbd{p} would get you back to
311 @samp{Help-P}. The node's title is underlined; it says what the node
312 is about (most nodes have titles).
313
314 This is a big node and it does not all fit on your display screen.
315 You can tell that there is more that is not visible because you
316 can see the string @samp{--Top-----} rather than @samp{--All----} near
317 the bottom right corner of the screen.
318
319 @kindex SPC @r{(Info mode)}
320 @kindex DEL @r{(Info mode)}
321 @kindex BACKSPACE @r{(Info mode)}
322 @findex Info-scroll-up
323 @findex Info-scroll-down
324 The @key{SPC}, @key{BACKSPACE} (or @key{DEL})@footnote{The key which
325 we call ``Backspace or DEL'' in this manual is labeled differently on
326 different keyboards. Look for a key which is a little ways above the
327 @key{ENTER} or @key{RET} key and which you normally use outside Emacs
328 to erase the character before the cursor, i.e.@: the character you
329 typed last. It might be labeled @samp{Backspace} or @samp{<-} or
330 @samp{DEL}, or sometimes @samp{Delete}.} and @kbd{b} commands exist to
331 allow you to ``move around'' in a node that does not all fit on the
332 screen at once. @key{SPC} moves forward, to show what was below the
333 bottom of the screen. @key{DEL} or @key{BACKSPACE} moves backward, to
334 show what was above the top of the screen (there is not anything above
335 the top until you have typed some spaces). In Emacs, @key{SPC} runs
336 the command @code{Info-scroll-up}, while @key{BACKSPACE} runs
337 @code{Info-scroll-down}.
338
339 @format
340 >> Now try typing a @key{SPC} (afterward, type a @key{BACKSPACE} to
341 return here).
342 @end format
343
344 When you type the @key{SPC}, the two lines that were at the bottom of
345 the screen appear at the top, followed by more lines. @key{DEL} or
346 @key{BACKSPACE} takes the two lines from the top and moves them to the
347 bottom, @emph{usually}, but if there are not a full screen's worth of
348 lines above them they may not make it all the way to the bottom.
349
350 If you are reading this in Emacs, note that the header line is
351 always visible, never scrolling off the display. That way, you can
352 always see the @samp{Next}, @samp{Prev}, and @samp{Up} links, and you
353 can conveniently go to one of these links from anywhere in the node by
354 clicking the mouse on one of these links.
355
356 @cindex reading Info documents top to bottom
357 @cindex Info documents as tutorials
358 @key{SPC} and @key{DEL} not only move forward and backward through
359 the current node. When these keys hit the beginning or the end of the
360 current node, they move to preceding or subsequent nodes.
361 Specifically, they scroll through all the nodes in an Info file as a
362 single logical sequence. In this sequence, a node's subnodes appear
363 following their parent. If a node has a menu, @key{SPC} takes you
364 into the subnodes listed in the menu, one by one. Once you reach the
365 end of a node, and have seen all of its subnodes, @key{SPC} takes you
366 to the next node or to the parent's next node. This is so you could
367 read the entire manual top to bottom by just typing @key{SPC}.
368
369 @kindex PAGEUP @r{(Info mode)}
370 @kindex PAGEDOWN @r{(Info mode)}
371 Many keyboards nowadays have two scroll keys labeled @samp{PageUp}
372 and @samp{PageDown} (or maybe @samp{Prior} and @samp{Next}). If your
373 keyboard has these keys, you can use them to move forward and backward
374 through the text, like with @key{SPC} and @key{BACKSPACE}. However,
375 unlike @key{SPC} and @key{BACKSPACE}, @key{PAGEUP} and @key{PAGEDOWN}
376 keys will never scroll beyond the beginning or the end of the current
377 node.
378
379 @kindex C-l @r{(Info mode)}
380 If your screen is ever garbaged, you can tell Info to print it out
381 again by typing @kbd{C-l} (@kbd{Control-L}, that is---hold down
382 @key{CTRL} and type @kbd{L} or @kbd{l}).
383
384 @format
385 >> Type @kbd{C-l} now.
386 @end format
387
388 @kindex b @r{(Info mode)}
389 To move back to the beginning of the node you are on, you can type
390 a lot of @key{BACKSPACE} keys. You can also type simply @kbd{b} for
391 beginning.
392
393 @format
394 >> Try that now. (We have put in enough verbiage to push this past
395 the first screenful, but screens are so big nowadays that perhaps it
396 isn't enough. You may need to shrink your Emacs or Info window.)
397 Then come back, with @key{SCS}s.
398 @end format
399
400 If your screen is very tall, all of this node might fit at once.
401 In that case, @kbd{b} won't do anything. Sorry; what can we do?
402
403 @kindex ? @r{(Info mode)}
404 @findex Info-summary
405 You have just learned a considerable number of commands. If you
406 want to use one but have trouble remembering which, you should type
407 a @kbd{?} (in Emacs it runs the @code{Info-summary} command) which
408 prints out a brief list of commands. When you are finished looking at
409 the list, make it go away by typing a @key{SPC} repeatedly.
410
411 @format
412 >> Type a @key{?} now. Press @key{SPC} to see consecutive screenfuls of
413 the list until finished. Then type @key{SPC} several times, until
414 it goes away.
415 @end format
416
417 (If you are using the stand-alone Info reader, type @kbd{C-x 0} to
418 return here, that is---press and hold @key{CTRL}, type an @kbd{x},
419 then release @key{CTRL} and @kbd{x}, and press @kbd{0}---a zero, not
420 the letter ``o''.)
421
422 From now on, you will encounter large nodes without warning, and
423 will be expected to know how to use @key{SPC} and @key{BACKSPACE} to
424 move around in them without being told. Since not all terminals have
425 the same size screen, it would be impossible to warn you anyway.
426
427 @format
428 >> Now type @kbd{n}, or click the mouse on the @samp{Next} link, to
429 see the description of the @kbd{m} command.
430 @end format
431
432 @node Help-M, Help-Adv, Help-^L, Getting Started
433 @comment node-name, next, previous, up
434 @section Menus and the @kbd{m} command
435
436 @cindex menus in an Info document
437 @cindex Info menus
438 With only the @kbd{n} (next) and @kbd{p} (previous) commands for
439 moving between nodes, nodes are restricted to a linear sequence.
440 Menus allow a branching structure. A menu is a list of other nodes
441 you can move to. It is actually just part of the text of the node
442 formatted specially so that Info can interpret it. The beginning of a
443 menu is always identified by a line which starts with @samp{* Menu:}.
444 A node contains a menu if and only if it has a line in it which starts
445 that way. The only menu you can use at any moment is the one in the
446 node you are in. To use a menu in any other node, you must move to
447 that node first.
448
449 After the start of the menu, each line that starts with a @samp{*}
450 identifies one subtopic. The line usually contains a brief name
451 for the subtopic (followed by a @samp{:}), the name of the node that talks
452 about that subtopic, and optionally some further description of the
453 subtopic. Lines in the menu that do not start with a @samp{*} have no
454 special meaning---they are only for the human reader's benefit and do
455 not define additional subtopics. Here is an example:
456
457 @example
458 * Foo: Node about FOO This tells about FOO
459 @end example
460
461 The subtopic name is Foo, and the node describing it is @samp{Node
462 about FOO}. The rest of the line is just for the reader's
463 Information. [[ But this line is not a real menu item, simply because
464 there is no line above it which starts with @samp{* Menu:}.]]
465
466 When you use a menu to go to another node (in a way that will be
467 described soon), what you specify is the subtopic name, the first
468 thing in the menu line. Info uses it to find the menu line, extracts
469 the node name from it, and goes to that node. The reason that there
470 is both a subtopic name and a node name is that the node name must be
471 meaningful to the computer and may therefore have to be ugly looking.
472 The subtopic name can be chosen just to be convenient for the user to
473 specify. Often the node name is convenient for the user to specify
474 and so both it and the subtopic name are the same. There is an
475 abbreviation for this:
476
477 @example
478 * Foo:: This tells about FOO
479 @end example
480
481 @noindent
482 This means that the subtopic name and node name are the same; they are
483 both @samp{Foo}.
484
485 @format
486 >> Now use @key{SPC} to find the menu in this node, then come back to
487 the front with a @kbd{b} and some @key{SPC}s. As you see, a menu is
488 actually visible in its node. If you cannot find a menu in a node
489 by looking at it, then the node does not have a menu and the
490 @kbd{m} command is not available.
491 @end format
492
493 @kindex m @r{(Info mode)}
494 The command to go to one of the subnodes is @kbd{m}---but @emph{do
495 not do it yet!} Before you use @kbd{m}, you need to learn about
496 commands which prompt you for more input. So far, you have learned
497 several commands that do not need additional input; when you typed
498 one, Info processed it and was instantly ready for another command.
499 The @kbd{m} command is different: it is incomplete without the
500 @dfn{name of the subtopic}. Once you have typed @kbd{m}, Info tries
501 to read the subtopic name.
502
503 Now look for the line containing many dashes near the bottom of the
504 screen. There is one more line beneath that one, but usually it is
505 blank. If it is empty, Info is ready for a command, such as @kbd{n}
506 or @kbd{b} or @key{SPC} or @kbd{m}. If that line contains text ending
507 in a colon, it means Info is trying to read more input for the last
508 command. At such times, commands do not work, because Info tries to
509 use them as the input it needs. You must either type your response and
510 finish the command you started, or type @kbd{Control-g} to cancel the
511 command. When you have done one of those things, the line becomes
512 blank again.
513
514 @findex Info-menu
515 The command to go to a subnode via a menu is @kbd{m}. After you type
516 the @kbd{m}, the line at the bottom of the screen says @samp{Menu item: }.
517 You must then type the name of the subtopic you want, and end it with
518 a @key{RET}. In Emacs, @kbd{m} runs the command @code{Info-menu}.
519
520 @cindex abbreviating Info subnodes
521 You can abbreviate the subtopic name. If the abbreviation is not
522 unique, the first matching subtopic is chosen. Some menus put
523 the shortest possible abbreviation for each subtopic name in capital
524 letters, so you can see how much you need to type. It does not
525 matter whether you use upper case or lower case when you type the
526 subtopic. You should not put any spaces at the end, or inside of the
527 item name, except for one space where a space appears in the item in
528 the menu.
529
530 @cindex completion of Info node names
531 You can also use the @dfn{completion} feature to help enter the subtopic
532 name. If you type the @key{TAB} key after entering part of a name, it will
533 magically fill in more of the name---as much as follows uniquely from
534 what you have entered.
535
536 If you move the cursor to one of the menu subtopic lines, then you do
537 not need to type the argument: you just type a @key{RET}, and it
538 stands for the subtopic of the line you are on.
539
540 Here is a menu to give you a chance to practice. This menu gives you
541 three ways of going to one place, Help-FOO:
542
543 @menu
544 * Foo: Help-FOO. A node you can visit for fun.
545 * Bar: Help-FOO. Strange! two ways to get to the same place.
546 * Help-FOO:: And yet another!
547 @end menu
548
549 @format
550 >> Now type just an @kbd{m} and see what happens:
551 @end format
552
553 Now you are ``inside'' an @kbd{m} command. Commands cannot be used
554 now; the next thing you will type must be the name of a subtopic.
555
556 You can change your mind about doing the @kbd{m} by typing
557 @kbd{Control-g}.
558
559 @format
560 >> Try that now; notice the bottom line clear.
561 @end format
562
563 @format
564 >> Then type another @kbd{m}.
565 @end format
566
567 @format
568 >> Now type @kbd{BAR}, the item name. Do not type @key{RET} yet.
569 @end format
570
571 While you are typing the item name, you can use the @key{DEL} (or
572 @key{BACKSPACE}) key to cancel one character at a time if you make a
573 mistake.
574
575 @format
576 >> Press @key{DEL} to cancel the @samp{R}. You could type another @kbd{R}
577 to replace it. But you do not have to, since @samp{BA} is a valid
578 abbreviation.
579 @end format
580
581 @format
582 >> Now you are ready to go. Type a @key{RET}.
583 @end format
584
585 After visiting @samp{Help-FOO}, you should return here.
586
587 Another way to move to the menu subtopic lines and between them is
588 to type @key{TAB}. Each time you type a @key{TAB}, you move to the
589 next subtopic line. To move to a previous subtopic line, type
590 @kbd{M-@key{TAB}}---that is, press and hold the @key{META} key and then
591 press @key{TAB}. (On some keyboards, the @key{META} key might be labeled
592 @samp{Alt}.)
593
594 Once you move cursor to a subtopic line, press @key{RET} to go to
595 that subtopic's node.
596
597 @cindex mouse support in Info mode
598 @kindex Mouse-2 @r{(Info mode)}
599 If your terminal supports a mouse, you have yet another way of going
600 to a subtopic. Move your mouse pointer to the subtopic line,
601 somewhere between the beginning @samp{*} and the colon @samp{:} which
602 ends the subtopic's brief name. You will see the subtopic's name
603 change its appearance (usually, its background color will change), and
604 the shape of the mouse pointer will change if your platform supports
605 that. After a while, if you leave the mouse on that spot, a tooltip
606 will pop up saying ``Mouse-2: go to that node''. (If the tooltips are
607 turned off or unavailable, this message is printed in the @dfn{echo
608 area}, the bottom screen line where you typed the menu subtopics in
609 response to the prompt.) @kbd{Mouse-2} is the second button of your
610 mouse counting from the left---the rightmost button for two-button
611 mice, the middle button for 3-button mice. So pressing @kbd{Mouse-2}
612 while the mouse pointer is on a menu subtopic goes to that subtopic.
613
614 @findex Info-mouse-follow-nearest-node
615 More generally, @kbd{Mouse-2} in an Info buffer runs the Emacs
616 command @code{Info-mouse-follow-nearest-node}, which finds the nearest
617 link to another node and goes there. For example, near a cross
618 reference it acts like @kbd{f}, in a menu it acts like @kbd{m}, on the
619 node's header line it acts like @kbd{n}, @kbd{p}, or @kbd{u}, etc. At
620 end of the node's text @kbd{Mouse-2} moves to the next node, or up if
621 there's no next node.
622
623 Here is another way to get to Help-FOO, a menu. You can ignore this
624 if you want, or else try it by typing @key{TAB} and then @key{RET}, or
625 clicking @kbd{Mouse-2} on it (but then please come back to here).
626
627 @menu
628 * Help-FOO::
629 @end menu
630
631 @format
632 >> Type @kbd{n} to see more commands.
633 @end format
634
635 @node Help-FOO, , , Help-M
636 @subsection The @kbd{u} command
637
638 Congratulations! This is the node @samp{Help-FOO}. It has an @samp{Up}
639 pointer @samp{Help-M}, the node you just came from via the @kbd{m}
640 command. This is the usual convention---the nodes you reach from a menu
641 have @samp{Up} nodes that lead back to the menu. Menus move Down in the
642 tree, and @samp{Up} moves Up. @samp{Previous}, on the other hand, is
643 usually used to ``stay on the same level but go backwards''.
644
645 @kindex u @r{(Info mode)}
646 @findex Info-up
647 You can go back to the node @samp{Help-M} by typing the command
648 @kbd{u} for ``Up'' (the Emacs command run by @kbd{u} is
649 @code{Info-up}). That puts you at the @emph{front} of the node---to
650 get back to where you were reading you have to type some @key{SPC}s.
651 (Some Info readers, such as the one built into Emacs, put you at the
652 same place where you were reading in @samp{Help-M}.)
653
654 Another way to go Up is to click on the @samp{Up} pointer shown in
655 the header line (provided that you have a mouse).
656
657 @format
658 >> Now type @kbd{u} to move back up to @samp{Help-M}.
659 @end format
660
661 @node Help-Adv, Help-Q, Help-M, Getting Started
662 @comment node-name, next, previous, up
663 @section Some advanced Info commands
664
665 The course is almost over, so please stick with it to the end.
666
667 @kindex l @r{(Info mode)}
668 @findex Info-last
669 @cindex going back in Info mode
670 If you have been moving around to different nodes and wish to
671 retrace your steps, the @kbd{l} command (@kbd{l} for @dfn{last}) will
672 do that, one node-step at a time. As you move from node to node, Info
673 records the nodes where you have been in a special history list. The
674 @kbd{l} command revisits nodes in the history list; each successive
675 @kbd{l} command moves one step back through the history.
676
677 If you have been following directions, ad @kbd{l} command now will get
678 you back to @samp{Help-M}. Another @kbd{l} command would undo the
679 @kbd{u} and get you back to @samp{Help-FOO}. Another @kbd{l} would undo
680 the @kbd{m} and get you back to @samp{Help-M}.
681
682 In Emacs, @kbd{l} runs the command @code{Info-last}.
683
684 @format
685 >> Try typing three @kbd{l}'s, pausing in between to see what each
686 @kbd{l} does. Then follow directions again and you will end up
687 back here.
688 @end format
689
690 Note the difference between @kbd{l} and @kbd{p}: @kbd{l} moves to
691 where @emph{you} last were, whereas @kbd{p} always moves to the node
692 which the header says is the @samp{Previous} node (from this node, the
693 @samp{Prev} link leads to @samp{Help-M}).
694
695 @kindex d @r{(Info mode)}
696 @findex Info-directory
697 @cindex go to Directory node
698 The @kbd{d} command (@code{Info-directory} in Emacs) gets you
699 instantly to the Directory node. This node, which is the first one
700 you saw when you entered Info, has a menu which leads (directly or
701 indirectly, through other menus), to all the nodes that exist. The
702 Directory node lists all the manuals and other Info documents that
703 are, or could be, installed on your system.
704
705 @format
706 >> Try doing a @kbd{d}, then do an @kbd{l} to return here (yes,
707 @emph{do} return).
708 @end format
709
710 @kindex t @r{(Info mode)}
711 @findex Info-top-node
712 @cindex go to Top node
713 The @kbd{t} command moves to the @samp{Top} node of the manual.
714 This is useful if you want to browse the manual's main menu, or select
715 some specific top-level menu item. The Emacs command run by @kbd{t}
716 is @code{Info-top-node}.
717
718 Sometimes, in Info documentation, you will see a cross reference.
719 Cross references look like this: @xref{Help-Cross, Cross}. That is a
720 real, live cross reference which is named @samp{Cross} and points at
721 the node named @samp{Help-Cross}.
722
723 @kindex f @r{(Info mode)}
724 @findex Info-follow-reference
725 @cindex cross references in Info documents
726 If you wish to follow a cross reference, you must use the @kbd{f}
727 command. The @kbd{f} must be followed by the cross reference name
728 (in this case, @samp{Cross}). If the cursor is on or near the cross
729 reference, Info suggests the name if the nearest reference in
730 parentheses; typing @key{RET} will follow that reference. You can
731 also type a different name, if the default is not what you want.
732 While you enter the name, you can use the @key{DEL} (or
733 @key{BACKSPACE}) key to edit your input. If you change your mind
734 about following any reference, you can use @kbd{Control-g} to cancel
735 the command.
736
737 Completion is available in the @kbd{f} command; you can complete among
738 all the cross reference names in the current node by typing a @key{TAB}.
739
740 @kbd{f} runs @code{Info-follow-reference} in Emacs.
741
742 @format
743 >> Type @kbd{f}, followed by @kbd{Cross}, and a @key{RET}.
744 @end format
745
746 To get a list of all the cross references in the current node, you can
747 type @kbd{?} after an @kbd{f}. The @kbd{f} continues to await a
748 cross reference name even after printing the list, so if you don't
749 actually want to follow a reference, you should type a @kbd{Control-g}
750 to cancel the @kbd{f}.
751
752 @format
753 >> Type @kbd{f?} to get a list of the cross references in this node. Then
754 type a @kbd{Control-g} and see how the @samp{f} gives up.
755 @end format
756
757 The @key{TAB} and @kbd{M-@key{TAB}} key, which move between
758 subtopics in a menu can move between cross references as well. Once
759 the cursor is on a cross reference, you can press @key{RET} to follow
760 that reference, just like you do in a menu.
761
762 Clicking @kbd{Mouse-2} on or near a cross reference also follows the
763 reference. You can see that the cross reference is mouse-sensitive by
764 moving the mouse pointer to the reference and watching how the
765 underlying text and the mouse pointer change in response.
766
767 @format
768 >> Now type @kbd{n} to see the last node of the course.
769 @end format
770
771 @c If a menu appears at the end of this node, remove it.
772 @c It is an accident of the menu updating command.
773
774 @node Advanced Info
775 @chapter Info for Experts
776
777 This chapter describes various advanced Info commands. (If you are
778 using a stand-alone Info reader, there are additional commands
779 specific to it, which are documented in several chapters of @ref{Top,,
780 GNU Info, info-stnd, GNU Info}.)
781
782 This chapter also explains how to write an Info as distinct from a
783 Texinfo file. (However, in most cases, writing a Texinfo file is
784 better, since you can use it @emph{both} to generate an Info file and
785 to make a printed manual. @xref{Top,, Overview of Texinfo, texinfo,
786 Texinfo: The GNU Documentation Format}.)
787
788 @menu
789 * Expert:: Advanced Info commands: g, s, e, and 1 - 5.
790 * Info Search:: How to search Info documents for specific subjects.
791 * Add:: Describes how to add new nodes to the hierarchy.
792 Also tells what nodes look like.
793 * Menus:: How to add to or create menus in Info nodes.
794 * Cross-refs:: How to add cross-references to Info nodes.
795 * Tags:: How to make tags tables for Info files.
796 * Checking:: Checking an Info File
797 * Emacs Info Variables:: Variables modifying the behavior of Emacs Info.
798 @end menu
799
800 @node Expert, Info Search, , Advanced Info
801 @comment node-name, next, previous, up
802 @section Advanced Info Commands
803
804 Here are some more Info commands that make it easier to move around.
805
806 @unnumberedsubsec @kbd{g} goes to a node by name
807
808 @kindex g @r{(Info mode)}
809 @findex Info-goto-node
810 @cindex go to a node by name
811 If you know a node's name, you can go there by typing @kbd{g}, the
812 name, and @key{RET}. Thus, @kbd{gTop@key{RET}} would go to the node
813 called @samp{Top} in this file. (This is equivalent to @kbd{t}, see
814 @ref{Help-Adv}.) @kbd{gExpert@key{RET}} would come back here.
815 @kbd{g} in Emacs runs the command @code{Info-goto-node}.
816
817 Unlike @kbd{m}, @kbd{g} does not allow the use of abbreviations.
818 But it does allow completion, so you can type @key{TAB} to complete a
819 partial node name.
820
821 @cindex go to another Info file
822 To go to a node in another file, you can include the file name in the
823 node name by putting it at the front, in parentheses. Thus,
824 @kbd{g(dir)Top@key{RET}} would go to the Info Directory node, which is
825 the node @samp{Top} in the Info file @file{dir}. Likewise,
826 @kbd{g(emacs)Top@key{RET}} goes to the top node of the Emacs manual.
827
828 The node name @samp{*} specifies the whole file. So you can look at
829 all of the current file by typing @kbd{g*@key{RET}} or all of any
830 other file with @kbd{g(@var{filename})@key{RET}}.
831
832 @unnumberedsubsec @kbd{1} -- @kbd{9} choose a menu subtopic by its number
833
834 @kindex 1 @r{through} 9 @r{(Info mode)}
835 @findex Info-nth-menu-item
836 @cindex select @var{n}'th menu item
837 If you begrudge each character of type-in which your system requires,
838 you might like to use the commands @kbd{1}, @kbd{2}, @kbd{3}, @kbd{4},
839 @dots{}, @kbd{9}. They are short for the @kbd{m} command together
840 with a name of a menu subtopic. @kbd{1} goes through the first item
841 in the current node's menu; @kbd{2} goes through the second item, etc.
842 In the stand-alone reader, @kbd{0} goes through the last menu item;
843 this is so you need not count how many entries are there. In Emacs,
844 the digit keys run the command @code{Info-nth-menu-item}.
845
846 If your display supports multiple fonts, and you are using Emacs'
847 Info mode to read Info files, the @samp{*} for the fifth menu item
848 stands out, either in color or in some other attribute, such as
849 underline, and so is the @samp{*} for the ninth item; this makes it
850 easy to see at a glance which number to use for an item.
851
852 Some terminals don't support colors or underlining. If you need to
853 actually count items, it is better to use @kbd{m} instead, and specify
854 the name, or use @key{TAB} to quickly move between menu items.
855
856 @unnumberedsubsec @kbd{e} makes Info document editable
857
858 @kindex e @r{(Info mode)}
859 @findex Info-edit
860 @cindex edit Info document
861 The Info command @kbd{e} changes from Info mode to an ordinary
862 Emacs editing mode, so that you can edit the text of the current node.
863 Type @kbd{C-c C-c} to switch back to Info. The @kbd{e} command is allowed
864 only if the variable @code{Info-enable-edit} is non-@code{nil}.
865
866 The @kbd{e} command only works in Emacs, where it runs the command
867 @code{Info-edit}. The stand-alone Info reader doesn't allow you to
868 edit the Info file, so typing @kbd{e} there goes to the end of the
869 current node.
870
871 @node Info Search, Add, Expert, Advanced Info
872 @comment node-name, next, previous, up
873 @section How to search Info documents for specific subjects
874
875 @cindex searching Info documents
876 @cindex Info document as a reference
877 The commands which move between and inside nodes allow you to read
878 the entire manual or its large portions. But what if you need to find
879 some information in the manual as fast as you can, and you don't know
880 or don't remember in what node to look for it? This need arises when
881 you use a manual as a @dfn{reference}, or when it is impractical to
882 read the entire manual before you start using the programs it
883 describes.
884
885 Info has powerful searching facilities that let you find things
886 quickly. You can search either the manual indices or its text.
887
888 @kindex i @r{(Info mode)}
889 @findex Info-index
890 Since most subjects related to what the manual describes should be
891 indexed, you should try the index search first. The @kbd{i} command
892 prompts you for a subject and then looks up that subject in the
893 indices. If it finds an index entry with the subject you typed, it
894 goes to the node to which that index entry points. You should browse
895 through that node to see whether the issue you are looking for is
896 described there. If it isn't, type @kbd{,} one or more times to go
897 through additional index entries which match your subject.
898
899 The @kbd{i} command finds all index entries which include the string
900 you typed @emph{as a substring}. For each match, Info shows in the
901 echo area the full index entry it found. Often, the text of the full
902 index entry already gives you enough information to decide whether it
903 is relevant to what you are looking for, so we recommend that you read
904 what Emacs shows in the echo are before looking at the node it
905 displays.
906
907 Since @kbd{i} looks for a substring, you can search for subjects even
908 if you are not sure how they are spelled in the index. For example,
909 suppose you want to find something that is pertinent to commands which
910 complete partial input (e.g., when you type @key{TAB}). If you want
911 to catch index entries that refer to ``complete'', ``completion'', and
912 ``completing'', you could type @kbd{icomplet@key{RET}}.
913
914 Info documents which describe programs should index the commands,
915 options, and key sequences that the program provides. If you are
916 looking for a description of a command, an option, or a key, just type
917 their names when @kbd{i} prompts you for a topic. For example, if you
918 want to read the description of what the @kbd{C-f} key does, type
919 @kbd{iC-f@key{RET}}. Here @kbd{C-f} are 3 literal characters
920 @samp{C}, @samp{-}, and @samp{f}, not the ``Control-f'' command key
921 you type inside Emacs to run the command bound to @kbd{C-f}.
922
923 In Emacs, @kbd{i} runs the command @code{Info-index}.
924
925 @kindex s @r{(Info mode)}
926 @findex Info-search
927 The @kbd{s} command allows you to search a whole file for a string.
928 It switches to the next node if and when that is necessary. You
929 type @kbd{s} followed by the string to search for, terminated by
930 @key{RET}. To search for the same string again, just @kbd{s} followed
931 by @key{RET} will do. The file's nodes are scanned in the order
932 they are in in the file, which has no necessary relationship to the
933 order that they may be in the tree structure of menus and @samp{next}
934 pointers. But normally the two orders are not very different. In any
935 case, you can always do a @kbd{b} to find out what node you have
936 reached, if the header is not visible (this can happen, because @kbd{s}
937 puts your cursor at the occurrence of the string, not at the beginning
938 of the node).
939
940 @kindex M-s @r{(Info mode)}
941 In Emacs, @kbd{Meta-s} is equivalent to @kbd{s}. That is for
942 compatibility with other GNU packages that use @kbd{M-s} for a similar
943 kind of search command. Both @kbd{s} and @kbd{M-s} run in Emacs the
944 command @code{Info-search}.
945
946
947 @node Add, Menus, Info Search, Advanced Info
948 @comment node-name, next, previous, up
949 @section Adding a new node to Info
950
951 To add a new topic to the list in the Info directory, you must:
952
953 @enumerate
954 @item
955 Create some nodes, in some file, to document that topic.
956 @item
957 Put that topic in the menu in the directory. @xref{Menus, Menu}.
958 @end enumerate
959
960 Usually, the way to create the nodes is with Texinfo (@pxref{Top,,
961 Overview of Texinfo, texinfo, Texinfo: The GNU Documentation Format});
962 this has the advantage that you can also make a printed manual from
963 them. However, if you want to edit an Info file, here is how.
964
965 @cindex node delimiters
966 The new node can live in an existing documentation file, or in a new
967 one. It must have a @samp{^_} character before it (invisible to the
968 user; this node has one but you cannot see it), and it ends with either
969 a @samp{^_}, a @samp{^L} (``formfeed''), or the end of file.@footnote{If
970 you put in a @samp{^L} to end a new node, be sure that there is a
971 @samp{^_} after it to start the next one, since @samp{^L} cannot
972 @emph{start} a node. Also, a nicer way to make a node boundary be a
973 page boundary as well is to put a @samp{^L} @emph{right after} the
974 @samp{^_}.}
975
976 The @samp{^_} starting a node must be followed by a newline or a
977 @samp{^L} newline, after which comes the node's header line. The header
978 line must give the node's name (by which Info finds it), and state the
979 names of the @samp{Next}, @samp{Previous}, and @samp{Up} nodes (if there
980 are any). As you can see, this node's @samp{Up} node is the node
981 @samp{Top}, which points at all the documentation for Info. The
982 @samp{Next} node is @samp{Menus}.
983
984 @cindex node header line format
985 @cindex format of node headers
986 The keywords @dfn{Node}, @dfn{Next}, @dfn{Previous}, and @dfn{Up}
987 may appear in any order, anywhere in the header line, but the
988 recommended order is the one in this sentence. Each keyword must be
989 followed by a colon, spaces and tabs, and then the appropriate name.
990 The name may be terminated with a tab, a comma, or a newline. A space
991 does not end it; node names may contain spaces. The case of letters
992 in the names is insignificant.
993
994 @cindex node name format
995 @cindex Directory node
996 A node name has two forms. A node in the current file is named by
997 what appears after the @samp{Node: } in that node's first line. For
998 example, this node's name is @samp{Add}. A node in another file is
999 named by @samp{(@var{filename})@var{node-within-file}}, as in
1000 @samp{(info)Add} for this node. If the file name starts with ``./'',
1001 then it is relative to the current directory; otherwise, it is
1002 relative starting from the standard directory for Info files of your
1003 site. The name @samp{(@var{filename})Top} can be abbreviated to just
1004 @samp{(@var{filename})}. By convention, the name @samp{Top} is used
1005 for the ``highest'' node in any single file---the node whose @samp{Up}
1006 points out of the file. The @samp{Directory} node is @file{(dir)}, it
1007 points to a file @file{dir} which holds a large menu listing all the
1008 Info documents installed on your site. The @samp{Top} node of a
1009 document file listed in the @samp{Directory} should have an @samp{Up:
1010 (dir)} in it.
1011
1012 @cindex unstructured documents
1013 The node name @kbd{*} is special: it refers to the entire file.
1014 Thus, @kbd{g*} shows you the whole current file. The use of the
1015 node @kbd{*} is to make it possible to make old-fashioned,
1016 unstructured files into nodes of the tree.
1017
1018 The @samp{Node:} name, in which a node states its own name, must not
1019 contain a file name, since when Info searches for a node, it does not
1020 expect a file name to be there. The @samp{Next}, @samp{Previous} and
1021 @samp{Up} names may contain them. In this node, since the @samp{Up}
1022 node is in the same file, it was not necessary to use one.
1023
1024 Note that the nodes in this file have a file name in the header
1025 line. The file names are ignored by Info, but they serve as comments
1026 to help identify the node for the user.
1027
1028 @node Menus, Cross-refs, Add, Advanced Info
1029 @comment node-name, next, previous, up
1030 @section How to Create Menus
1031
1032 Any node in the Info hierarchy may have a @dfn{menu}---a list of subnodes.
1033 The @kbd{m} command searches the current node's menu for the topic which it
1034 reads from the terminal.
1035
1036 @cindex menu and menu entry format
1037 A menu begins with a line starting with @samp{* Menu:}. The rest of the
1038 line is a comment. After the starting line, every line that begins
1039 with a @samp{* } lists a single topic. The name of the topic--what
1040 the user must type at the @kbd{m}'s command prompt to select this
1041 topic---comes right after the star and space, and is followed by a
1042 colon, spaces and tabs, and the name of the node which discusses that
1043 topic. The node name, like node names following @samp{Next}, @samp{Previous}
1044 and @samp{Up}, may be terminated with a tab, comma, or newline; it may also
1045 be terminated with a period.
1046
1047 If the node name and topic name are the same, then rather than
1048 giving the name twice, the abbreviation @samp{* @var{name}::} may be
1049 used (and should be used, whenever possible, as it reduces the visual
1050 clutter in the menu).
1051
1052 It is considerate to choose the topic names so that they differ
1053 from each other very near the beginning---this allows the user to type
1054 short abbreviations. In a long menu, it is a good idea to capitalize
1055 the beginning of each item name which is the minimum acceptable
1056 abbreviation for it (a long menu is more than 5 or so entries).
1057
1058 The nodes listed in a node's menu are called its ``subnodes'', and it
1059 is their ``superior''. They should each have an @samp{Up:} pointing at
1060 the superior. It is often useful to arrange all or most of the subnodes
1061 in a sequence of @samp{Next} and @samp{Previous} pointers so that
1062 someone who wants to see them all need not keep revisiting the Menu.
1063
1064 The Info Directory is simply the menu of the node @samp{(dir)Top}---that
1065 is, node @samp{Top} in file @file{.../info/dir}. You can put new entries
1066 in that menu just like any other menu. The Info Directory is @emph{not} the
1067 same as the file directory called @file{info}. It happens that many of
1068 Info's files live in that file directory, but they do not have to; and
1069 files in that directory are not automatically listed in the Info
1070 Directory node.
1071
1072 Also, although the Info node graph is claimed to be a ``hierarchy'',
1073 in fact it can be @emph{any} directed graph. Shared structures and
1074 pointer cycles are perfectly possible, and can be used if they are
1075 appropriate to the meaning to be expressed. There is no need for all
1076 the nodes in a file to form a connected structure. In fact, this file
1077 has two connected components. You are in one of them, which is under
1078 the node @samp{Top}; the other contains the node @samp{Help} which the
1079 @kbd{h} command goes to. In fact, since there is no garbage
1080 collector, nothing terrible happens if a substructure is not pointed
1081 to, but such a substructure is rather useless since nobody can
1082 ever find out that it exists.
1083
1084 @node Cross-refs, Tags, Menus, Advanced Info
1085 @comment node-name, next, previous, up
1086 @section Creating Cross References
1087
1088 @cindex cross reference format
1089 A cross reference can be placed anywhere in the text, unlike a menu
1090 item which must go at the front of a line. A cross reference looks
1091 like a menu item except that it has @samp{*note} instead of @samp{*}.
1092 It @emph{cannot} be terminated by a @samp{)}, because @samp{)}'s are
1093 so often part of node names. If you wish to enclose a cross reference
1094 in parentheses, terminate it with a period first. Here are two
1095 examples of cross references pointers:
1096
1097 @example
1098 *Note details: commands. (See *note 3: Full Proof.)
1099 @end example
1100
1101 @noindent
1102 @emph{These are just examples.} The places they ``lead to'' do not
1103 really exist!
1104
1105 @menu
1106 * Help-Cross:: Target of a cross-reference.
1107 @end menu
1108
1109
1110 @node Help-Cross, , , Cross-refs
1111 @subsection The node reached by the cross reference in Info
1112
1113 This is the node reached by the cross reference named @samp{Cross}.
1114
1115 While this node is specifically intended to be reached by a cross
1116 reference, most cross references lead to nodes that ``belong''
1117 someplace else far away in the structure of an Info document. So you
1118 cannot expect this node to have a @samp{Next}, @samp{Previous} or
1119 @samp{Up} links pointing back to where you came from. In general, the
1120 @kbd{l} (el) command is the only way to get back there.
1121
1122 @format
1123 >> Type @kbd{l} to return to the node where the cross reference was.
1124 @end format
1125
1126 @node Help-Q, , Help-Adv, Getting Started
1127 @comment node-name, next, previous, up
1128 @section Quitting Info
1129
1130 @kindex q @r{(Info mode)}
1131 @findex Info-exit
1132 @cindex quitting Info mode
1133 To get out of Info, back to what you were doing before, type @kbd{q}
1134 for @dfn{Quit}. This runs @code{Info-exit} in Emacs.
1135
1136 This is the end of the basic course on using Info. You have learned
1137 how to move in an Info document, and how to follow menus and cross
1138 references. This makes you ready for reading manuals top to bottom,
1139 as new users should do when they learn a new package.
1140
1141 Another set of Info commands is useful when you need to find
1142 something quickly in a manual---that is, when you need to use a manual
1143 as a reference rather than as a tutorial. We urge you to make learn
1144 these search commands as well. If you want to do that now, follow this
1145 cross reference to @ref{Info Search}.
1146
1147 Yet another set of commands are meant for experienced users; you can
1148 find them by looking in the Directory node for documentation on Info.
1149 Finding them will be a good exercise in using Info in the usual
1150 manner.
1151
1152 @format
1153 >> Type @kbd{d} to go to the Info directory node; then type
1154 @kbd{mInfo} and Return, to get to the node about Info and
1155 see what other help is available.
1156 @end format
1157
1158
1159 @node Tags, Checking, Cross-refs, Advanced Info
1160 @comment node-name, next, previous, up
1161 @section Tags Tables for Info Files
1162
1163 @cindex tags tables in info files
1164 You can speed up the access to nodes of a large Info file by giving
1165 it a tags table. Unlike the tags table for a program, the tags table for
1166 an Info file lives inside the file itself and is used
1167 automatically whenever Info reads in the file.
1168
1169 @findex Info-tagify
1170 To make a tags table, go to a node in the file using Emacs Info mode and type
1171 @kbd{M-x Info-tagify}. Then you must use @kbd{C-x C-s} to save the
1172 file. Info files produced by the @code{makeinfo} command that is part
1173 of the Texinfo package always have tags tables to begin with.
1174
1175 @cindex stale tags tables
1176 @cindex update Info tags table
1177 Once the Info file has a tags table, you must make certain it is up
1178 to date. If you edit an Info file directly (as opposed to editing its
1179 Texinfo source), and, as a result of deletion of text, any node moves back
1180 more than a thousand characters in the file from the position
1181 recorded in the tags table, Info will no longer be able to find that
1182 node. To update the tags table, use the @code{Info-tagify} command
1183 again.
1184
1185 An Info file tags table appears at the end of the file and looks like
1186 this:
1187
1188 @example
1189 ^_^L
1190 Tag Table:
1191 File: info, Node: Cross-refs^?21419
1192 File: info, Node: Tags^?22145
1193 ^_
1194 End Tag Table
1195 @end example
1196
1197 @noindent
1198 Note that it contains one line per node, and this line contains
1199 the beginning of the node's header (ending just after the node name),
1200 a @samp{DEL} character, and the character position in the file of the
1201 beginning of the node.
1202
1203
1204 @node Checking, Emacs Info Variables, Tags, Advanced Info
1205 @section Checking an Info File
1206
1207 When creating an Info file, it is easy to forget the name of a node when
1208 you are making a pointer to it from another node. If you put in the
1209 wrong name for a node, this is not detected until someone tries to go
1210 through the pointer using Info. Verification of the Info file is an
1211 automatic process which checks all pointers to nodes and reports any
1212 pointers which are invalid. Every @samp{Next}, @samp{Previous}, and
1213 @samp{Up} is checked, as is every menu item and every cross reference. In
1214 addition, any @samp{Next} which does not have a @samp{Previous} pointing
1215 back is reported. Only pointers within the file are checked, because
1216 checking pointers to other files would be terribly slow. But those are
1217 usually few.
1218
1219 @findex Info-validate
1220 To check an Info file, do @kbd{M-x Info-validate} while looking at any
1221 node of the file with Emacs Info mode.
1222
1223 @node Emacs Info Variables, , Checking, Advanced Info
1224 @section Emacs Info-mode Variables
1225
1226 The following variables may modify the behavior of Info-mode in Emacs;
1227 you may wish to set one or several of these variables interactively, or
1228 in your @file{~/.emacs} init file. @xref{Examining, Examining and Setting
1229 Variables, Examining and Setting Variables, emacs, The GNU Emacs
1230 Manual}. The stand-alone Info reader program has its own set of
1231 variables, described in @ref{Variables,, Manipulating Variables,
1232 info-stnd, GNU Info}.
1233
1234 @vtable @code
1235 @item Info-directory-list
1236 The list of directories to search for Info files. Each element is a
1237 string (directory name) or @code{nil} (try default directory). If not
1238 initialized Info uses the environment variable @env{INFOPATH} to
1239 initialize it, or @code{Info-default-directory-list} if there is no
1240 @env{INFOPATH} variable in the environment.
1241
1242 @item Info-additional-directory-list
1243 A list of additional directories to search for Info documentation files.
1244 These directories are not searched for merging the @file{dir} file.
1245
1246 @item Info-fontify
1247 When set to a non-@code{nil} value, enables highlighting of Info
1248 files. The default is @code{t}. You can change how the highlighting
1249 looks by customizing the faces @code{info-node}, @code{info-menu-5},
1250 @code{info-xref}, @code{info-header-xref}, @code{info-header-node},
1251 @code{info-title-@var{n}-face} (where @var{n} is the level of the
1252 section, a number between 1 and 4), and @code{info-menu-header}. To
1253 customize a face, type @kbd{M-x customize-face @key{RET} @var{face}
1254 @key{RET}}, where @var{face} is one of the face names listed here.
1255
1256 @item Info-use-header-line
1257 If non-@code{nil}, Emacs puts in the Info buffer a header line showing
1258 the @samp{Next}, @samp{Prev}, and @samp{Up} links. A header line does
1259 not scroll with the rest of the buffer, making these links always
1260 visible.
1261
1262 @item Info-scroll-prefer-subnodes
1263 If set to a non-@code{nil} value, @key{SPC} and @key{BACKSPACE} (or
1264 @key{DEL}) keys in a menu visit subnodes of the current node before
1265 scrolling to its end or beginning, respectively. For example, if the
1266 node's menu appears on the screen, the next @key{SPC} moves to a
1267 subnode indicated by the following menu item. Setting this option to
1268 @code{nil} results in behavior similar to the stand-alone Info reader
1269 program, which visits the first subnode from the menu only when you
1270 hit the end of the current node. The default is @code{t}.
1271
1272 @item Info-enable-active-nodes
1273 When set to a non-@code{nil} value, allows Info to execute Lisp code
1274 associated with nodes. The Lisp code is executed when the node is
1275 selected. The Lisp code to be executed should follow the node
1276 delimiter (the @samp{DEL} character) and an @samp{execute: } tag, like
1277 this:
1278
1279 @example
1280 ^_execute: (message "This is an active node!")
1281 @end example
1282
1283 @item Info-enable-edit
1284 Set to @code{nil}, disables the @samp{e} (@code{Info-edit}) command. A
1285 non-@code{nil} value enables it. @xref{Add, Edit}.
1286 @end vtable
1287
1288
1289 @node Creating an Info File
1290 @chapter Creating an Info File from a Texinfo File
1291
1292 @code{makeinfo} is a utility that converts a Texinfo file into an Info
1293 file; @code{texinfo-format-region} and @code{texinfo-format-buffer} are
1294 GNU Emacs functions that do the same.
1295
1296 @xref{Top,, Overview of Texinfo, texinfo, Texinfo: The GNU
1297 Documentation Format}, to learn how to write a Texinfo file.
1298
1299 @xref{Creating an Info File,,, texinfo, Texinfo: The GNU Documentation
1300 Format}, to learn how to create an Info file from a Texinfo file.
1301
1302 @xref{Installing an Info File,,, texinfo, Texinfo: The GNU
1303 Documentation Format}, to learn how to install an Info file after you
1304 have created one.
1305
1306 @node Index
1307 @unnumbered Index
1308
1309 This is an alphabetical listing of all the commands, variables, and
1310 topics discussed in this document.
1311
1312 @printindex cp
1313
1314 @bye