help.texi 27.6 KB
Newer Older
Dave Love's avatar
#  
Dave Love committed
1
@c This is part of the Emacs manual.
2 3
@c Copyright (C) 1985, 1986, 1987, 1993, 1994, 1995, 1997, 2000, 2001,
@c   2002, 2003, 2004, 2005 Free Software Foundation, Inc.
Dave Love's avatar
#  
Dave Love committed
4 5 6 7 8 9 10 11 12 13 14
@c See file emacs.texi for copying conditions.
@node Help, Mark, M-x, Top
@chapter Help
@kindex Help
@cindex help
@cindex self-documentation
@findex help-command
@kindex C-h
@kindex F1

  Emacs provides extensive help features accessible through a single
Eli Zaretskii's avatar
Eli Zaretskii committed
15
character, @kbd{C-h}.  @kbd{C-h} is a prefix key that is used for
16
commands that display documentation.  The characters that you can type after
Dave Love's avatar
#  
Dave Love committed
17 18 19 20 21 22 23 24 25 26 27
@kbd{C-h} are called @dfn{help options}.  One help option is @kbd{C-h};
that is how you ask for help about using @kbd{C-h}.  To cancel, type
@kbd{C-g}.  The function key @key{F1} is equivalent to @kbd{C-h}.

@kindex C-h C-h
@findex help-for-help
  @kbd{C-h C-h} (@code{help-for-help}) displays a list of the possible
help options, each with a brief description.  Before you type a help
option, you can use @key{SPC} or @key{DEL} to scroll through the list.

  @kbd{C-h} or @key{F1} means ``help'' in various other contexts as
28 29 30 31
well.  After a prefix key, it displays a list of the alternatives that
can follow the prefix key.  (A few prefix keys don't support
@kbd{C-h}, because they define other meanings for it, but they all
support @key{F1}.)
Dave Love's avatar
#  
Dave Love committed
32 33

  Most help buffers use a special major mode, Help mode, which lets you
Dave Love's avatar
Dave Love committed
34
scroll conveniently with @key{SPC} and @key{DEL}.  It also offers
35 36
hyperlinks to URLs and further help regarding cross-referenced names, Info
nodes, customization buffers and the like.  @xref{Help Mode}.
Dave Love's avatar
#  
Dave Love committed
37

38 39
@cindex searching documentation efficiently
@cindex looking for a subject in documentation
40
  If you are looking for a certain feature, but don't know where
Richard M. Stallman's avatar
Richard M. Stallman committed
41
exactly it is documented, and aren't sure of the name of a
42
related command or variable, we recommend trying these methods.  Usually
43 44
it is best to start with an apropos command, then try searching the
manual index, then finally look in the FAQ and the package keywords.
45 46

@table @kbd
47 48 49
@item C-h a @var{topics} @key{RET}
This searches for commands whose names match @var{topics}, which
should be a keyword, a list of keywords, or a regular expression
Luc Teirlinck's avatar
Luc Teirlinck committed
50
(@pxref{Regexps}).  This command displays all the matches in a new
51
buffer.  @xref{Apropos}.
Dave Love's avatar
Dave Love committed
52

53
@item C-h i d m emacs @key{RET} i @var{topic} @key{RET}
54
This looks up @var{topic} in the indices of the Emacs on-line manual.
Eli Zaretskii's avatar
Eli Zaretskii committed
55
If there are several matches, Emacs displays the first one.  You can then
Luc Teirlinck's avatar
Luc Teirlinck committed
56
press @kbd{,} to move to other matches, until you find what you are
57 58
looking for.

59
@item C-h i d m emacs @key{RET} s @var{topic} @key{RET}
60 61 62 63
Similar, but searches for @var{topic} (which can be a regular
expression) in the @emph{text} of the manual rather than in its
indices.

Juri Linkov's avatar
Juri Linkov committed
64
@item C-h C-f
65 66
This brings up the Emacs FAQ.  You can use the Info commands
to browse it.
67

68
@item C-h p
69
Finally, you can try looking up a suitable package using keywords
70
pertinent to the feature you need.  @xref{Library Keywords}.
71 72
@end table

73
  To find the documentation of a key sequence or a menu item, type
74
@kbd{C-h K} and then type that key sequence or select the menu
75 76
item.  This looks up the description of the command invoked by the key
or the menu in the appropriate manual (not necessarily the Emacs
77
manual).  Likewise, use @kbd{C-h F} for reading documentation of a
78 79
command.

Dave Love's avatar
#  
Dave Love committed
80 81 82 83 84 85 86 87 88
@menu
* Help Summary::	Brief list of all Help commands.
* Key Help::		Asking what a key does in Emacs.
* Name Help::		Asking about a command, variable or function name.
* Apropos::		Asking what pertains to a given topic.
* Library Keywords::	Finding Lisp libraries by keywords (topics).
* Language Help::       Help relating to international language support.
* Help Mode::           Special features of Help mode and Help buffers.
* Misc Help::		Other help commands.
89
* Help Files::          Commands to display pre-written help files.
Dave Love's avatar
Dave Love committed
90
* Help Echo::           Help on active text and tooltips (`balloon help')
Dave Love's avatar
#  
Dave Love committed
91 92 93 94 95
@end menu

@iftex
@node Help Summary
@end iftex
Karl Berry's avatar
Karl Berry committed
96
@ifnottex
Dave Love's avatar
#  
Dave Love committed
97 98
@node Help Summary
@section Help Summary
Karl Berry's avatar
Karl Berry committed
99
@end ifnottex
Dave Love's avatar
#  
Dave Love committed
100

101 102 103
  Here is a summary of the Emacs interactive help commands.
@xref{Help Files}, for other help commands that just display a
pre-written file of information.
Dave Love's avatar
#  
Dave Love committed
104 105

@table @kbd
106 107 108
@item C-h a @var{topics} @key{RET}
Display a list of commands whose names match @var{topics}
(@code{apropos-command}; @pxref{Apropos}).
Dave Love's avatar
#  
Dave Love committed
109 110 111 112 113
@item C-h b
Display a table of all key bindings in effect now, in this order: minor
mode bindings, major mode bindings, and global bindings
(@code{describe-bindings}).
@item C-h c @var{key}
Eli Zaretskii's avatar
Eli Zaretskii committed
114
Show the name of the command that @var{key} runs
Richard M. Stallman's avatar
Richard M. Stallman committed
115 116
(@code{describe-key-briefly}).  Here @kbd{c} stands for ``character.''
For more extensive information on @var{key}, use @kbd{C-h k}.
117 118 119
@item C-h d @var{topics} @key{RET}
Display a list of commands and variables whose documentation matches
@var{topics} (@code{apropos-documentation}).
120 121 122
@item C-h e
Display the @code{*Messages*} buffer
(@code{view-echo-area-messages}).
Dave Love's avatar
#  
Dave Love committed
123 124 125 126 127
@item C-h f @var{function} @key{RET}
Display documentation on the Lisp function named @var{function}
(@code{describe-function}).  Since commands are Lisp functions,
a command name may be used.
@item C-h h
128
Display the @file{HELLO} file, which shows examples of various character
Dave Love's avatar
#  
Dave Love committed
129 130 131 132 133 134 135 136 137 138 139 140 141 142 143
sets.
@item C-h i
Run Info, the program for browsing documentation files (@code{info}).
The complete Emacs manual is available on-line in Info.
@item C-h k @var{key}
Display the name and documentation of the command that @var{key} runs
(@code{describe-key}).
@item C-h l
Display a description of the last 100 characters you typed
(@code{view-lossage}).
@item C-h m
Display documentation of the current major mode (@code{describe-mode}).
@item C-h p
Find packages by topic keyword (@code{finder-by-keyword}).
@item C-h s
144
Display the current contents of the syntax table, plus an explanation of
Dave Love's avatar
#  
Dave Love committed
145 146 147 148
what they mean (@code{describe-syntax}).  @xref{Syntax}.
@item C-h t
Enter the Emacs interactive tutorial (@code{help-with-tutorial}).
@item C-h v @var{var} @key{RET}
Eli Zaretskii's avatar
Eli Zaretskii committed
149
Display the documentation of the Lisp variable @var{var}
Dave Love's avatar
#  
Dave Love committed
150 151
(@code{describe-variable}).
@item C-h w @var{command} @key{RET}
Eli Zaretskii's avatar
Eli Zaretskii committed
152
Show which keys run the command named @var{command} (@code{where-is}).
Dave Love's avatar
#  
Dave Love committed
153
@item C-h C @var{coding} @key{RET}
Eli Zaretskii's avatar
Eli Zaretskii committed
154
Describe coding system @var{coding}
Dave Love's avatar
#  
Dave Love committed
155 156 157 158 159 160
(@code{describe-coding-system}).
@item C-h C @key{RET}
Describe the coding systems currently in use.
@item C-h I @var{method} @key{RET}
Describe an input method (@code{describe-input-method}).
@item C-h L @var{language-env} @key{RET}
Richard M. Stallman's avatar
Richard M. Stallman committed
161
Display information on the character sets, coding systems, and input
Eli Zaretskii's avatar
Eli Zaretskii committed
162
methods used for language environment @var{language-env}
Dave Love's avatar
#  
Dave Love committed
163
(@code{describe-language-environment}).
164
@item C-h F @var{function} @key{RET}
Dave Love's avatar
#  
Dave Love committed
165 166
Enter Info and go to the node documenting the Emacs function @var{function}
(@code{Info-goto-emacs-command-node}).
167
@item C-h K @var{key}
Dave Love's avatar
#  
Dave Love committed
168 169
Enter Info and go to the node where the key sequence @var{key} is
documented (@code{Info-goto-emacs-key-command-node}).
170
@item C-h S @var{symbol} @key{RET}
Dave Love's avatar
#  
Dave Love committed
171 172
Display the Info documentation on symbol @var{symbol} according to the
programming language you are editing (@code{info-lookup-symbol}).
173 174
@item C-h .
Display a help message associated with special text areas, such as
175
links in @samp{*Help*} buffers (@code{display-local-help}).
Dave Love's avatar
#  
Dave Love committed
176 177 178 179 180 181 182 183 184
@end table

@node Key Help
@section Documentation for a Key

@kindex C-h c
@findex describe-key-briefly
  The most basic @kbd{C-h} options are @kbd{C-h c}
(@code{describe-key-briefly}) and @w{@kbd{C-h k}} (@code{describe-key}).
185 186
@kbd{C-h c @var{key}} displays in the echo area the name of the command
that @var{key} is bound to.  For example, @kbd{C-h c C-f} displays
Dave Love's avatar
#  
Dave Love committed
187 188 189 190 191 192 193 194 195 196 197 198 199
@samp{forward-char}.  Since command names are chosen to describe what
the commands do, this is a good way to get a very brief description of
what @var{key} does.

@kindex C-h k
@findex describe-key
  @kbd{C-h k @var{key}} is similar but gives more information: it
displays the documentation string of the command as well as its name.
This is too big for the echo area, so a window is used for the display.

  @kbd{C-h c} and @kbd{C-h k} work for any sort of key sequences,
including function keys and mouse events.

200 201 202 203 204 205 206
@kindex C-h w
@findex where-is
  @kbd{C-h w @var{command} @key{RET}} tells you what keys are bound to
@var{command}.  It displays a list of the keys in the echo area.  If it
says the command is not on any key, you must use @kbd{M-x} to run it.
@kbd{C-h w} runs the command @code{where-is}.

Dave Love's avatar
#  
Dave Love committed
207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225
@node Name Help
@section Help by Command or Variable Name

@kindex C-h f
@findex describe-function
  @kbd{C-h f} (@code{describe-function}) reads the name of a Lisp function
using the minibuffer, then displays that function's documentation string
in a window.  Since commands are Lisp functions, you can use this to get
the documentation of a command that you know by name.  For example,

@example
C-h f auto-fill-mode @key{RET}
@end example

@noindent
displays the documentation of @code{auto-fill-mode}.  This is the only
way to get the documentation of a command that is not bound to any key
(one which you would normally run using @kbd{M-x}).

226 227 228 229 230 231 232 233 234
  @kbd{C-h f} is also useful for Lisp functions that you are planning
to use in a Lisp program.  For example, if you have just written the
expression @code{(make-vector len)} and want to check that you are
using @code{make-vector} properly, type @kbd{C-h f make-vector
@key{RET}}.  Because @kbd{C-h f} allows all function names, not just
command names, you may find that some of your favorite completion
abbreviations that work in @kbd{M-x} don't work in @kbd{C-h f}.  An
abbreviation may be unique among command names, yet fail to be unique
when other function names are allowed.
Dave Love's avatar
#  
Dave Love committed
235

Eli Zaretskii's avatar
Eli Zaretskii committed
236 237 238 239 240 241 242
  The default function name for @kbd{C-h f} to describe, if you type
just @key{RET}, is the name of the function called by the innermost Lisp
expression in the buffer around point, @emph{provided} that is a valid,
defined Lisp function name.  For example, if point is located following
the text @samp{(make-vector (car x)}, the innermost list containing
point is the one that starts with @samp{(make-vector}, so the default is
to describe the function @code{make-vector}.
Dave Love's avatar
#  
Dave Love committed
243 244 245 246 247 248 249 250 251 252

  @kbd{C-h f} is often useful just to verify that you have the right
spelling for the function name.  If @kbd{C-h f} mentions a name from the
buffer as the default, that name must be defined as a Lisp function.  If
that is all you want to know, just type @kbd{C-g} to cancel the @kbd{C-h
f} command, then go on editing.

  @kbd{C-h v} (@code{describe-variable}) is like @kbd{C-h f} but describes
Lisp variables instead of Lisp functions.  Its default is the Lisp symbol
around or before point, but only if that is the name of a known Lisp
253 254 255 256 257 258 259 260 261
variable.  @xref{Variables}.

  Help buffers describing Emacs variables and functions normally have
hyperlinks to the definition, if you have the source files installed.
(@xref{Hyperlinking}.)  If you know Lisp (or C), this provides the
ultimate documentation.  If you don't know Lisp, you should learn it.
If you are just @emph{using} Emacs, treating Emacs as an object
(file), then you don't really love it.  For true intimacy with your
editor, you need to read the source code.
262

Dave Love's avatar
#  
Dave Love committed
263 264 265
@node Apropos
@section Apropos

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
  A more sophisticated sort of question to ask is, ``What are the
commands for working with files?''  The @dfn{apropos} commands ask
such questions---they look for things whose names match an
@dfn{apropos pattern}, which means either a word, a list of words, or
a regular expression.  Each apropos command displays a list of
matching items in a special buffer.

@table @kbd
@item C-h a @var{pattern} @key{RET}
Search for commands whose names match @var{pattern}.

@item M-x apropos @key{RET} @var{pattern} @key{RET}
Similar, but it searches for noninteractive functions and for
variables, as well as commands.

@item M-x apropos-variable @key{RET} @var{pattern} @key{RET}
Similar, but it searches for variables only.

@item M-x apropos-value @key{RET} @var{pattern} @key{RET}
Similar, but it searches for variables based on their values, or
functions based on their definitions.

@item C-h d @var{pattern} @key{RET}
Search the @emph{documentation strings} (the built-in short
descriptions) of all variables and functions (not their names) for a
match for @var{pattern}.
@end table

Dave Love's avatar
#  
Dave Love committed
294 295 296
@kindex C-h a
@findex apropos-command
@cindex apropos
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
  To find the commands that work on files, type @kbd{C-h a file
@key{RET}}.  This displays a list of all command names that contain
@samp{file}, including @code{copy-file}, @code{find-file}, and so on.
With each command name appears a brief description of how to use the
command, and what keys you can currently invoke it with.  For example,
it would say that you can invoke @code{find-file} by typing @kbd{C-x
C-f}.  The @kbd{a} in @kbd{C-h a} stands for ``Apropos''; @kbd{C-h a}
runs the command @code{apropos-command}.  This command normally checks
only commands (interactive functions); if you specify a prefix
argument, it checks noninteractive functions as well.

  If you want more information about a function definition, variable or
symbol property listed in the Apropos buffer, you can click on it with
@kbd{Mouse-1} or @kbd{Mouse-2}, or move there and type @key{RET}.

  @kbd{C-h a} with a single word can find too many matches.  Don't
just give up; you can give Apropos a list of words to search for.
When you specify more than one word in the apropos pattern, a name
must contain at least two of the words in order to match.  Thus, if
you are looking for commands to kill a chunk of text before point, you
could try @kbd{C-h a kill back backward behind before @key{RET}}.

  For even greater flexibility, you can specify a regular expression
(@pxref{Regexps}).  An apropos pattern is interpreted as a regular
expression if it contains any of the regular expression special
characters, @samp{^$*+?.\[}.
Dave Love's avatar
#  
Dave Love committed
323 324

  Here is a set of arguments to give to @kbd{C-h a} that covers many
325 326 327 328
classes of Emacs commands, since there are strong conventions for
naming the standard Emacs commands.  By giving you a feel for the
naming conventions, this set should also serve to aid you in
developing a technique for picking Apropos keywords.
Dave Love's avatar
#  
Dave Love committed
329 330 331 332 333 334 335 336 337

@quotation
char, line, word, sentence, paragraph, region, page, sexp, list, defun,
rect, buffer, frame, window, face, file, dir, register, mode, beginning, end,
forward, backward, next, previous, up, down, search, goto, kill, delete,
mark, insert, yank, fill, indent, case, change, set, what, list, find,
view, describe, default.
@end quotation

338
@findex apropos
Luc Teirlinck's avatar
Luc Teirlinck committed
339
  To list all Lisp symbols that contain a match for an Apropos pattern,
340 341 342 343 344
not just the ones that are defined as commands, use the command
@kbd{M-x apropos} instead of @kbd{C-h a}.  This command does not check
key bindings by default; specify a numeric argument if you want it to
check them.

Dave Love's avatar
#  
Dave Love committed
345
@findex apropos-variable
346 347
  To list user-customizable variables that match an apropos pattern,
use the command @kbd{M-x apropos-variable}.  If you specify a prefix
348
argument, it checks all variables.
Dave Love's avatar
#  
Dave Love committed
349

350
@kindex C-h d
Dave Love's avatar
#  
Dave Love committed
351
@findex apropos-documentation
352 353 354
  The @code{apropos-documentation} command is like @code{apropos}
except that it searches documentation strings instead of symbol names
for matches for the specified Apropos pattern.
Dave Love's avatar
#  
Dave Love committed
355 356

@findex apropos-value
357 358 359 360
  The @code{apropos-value} command is like @code{apropos} except that
it searches variables' values for matches for the pattern.  With a
prefix argument, it also checks symbols' function definitions and
property lists.
Dave Love's avatar
#  
Dave Love committed
361 362 363 364 365

@vindex apropos-do-all
  If the variable @code{apropos-do-all} is non-@code{nil}, the commands
above all behave as if they had been given a prefix argument.

366
@vindex apropos-sort-by-scores
367
@cindex apropos search results, order by score
368 369 370 371 372
  By default, Apropos lists the search results in alphabetical order.
If the variable @code{apropos-sort-by-scores} is non-@code{nil},
Apropos tries to guess the relevance of each result, and displays the
most relevant ones first.

373 374
@vindex apropos-documentation-sort-by-scores
  By default, Apropos lists the search results for
375 376
@code{apropos-documentation} in order of relevance of the match.  If
the variable @code{apropos-documentation-sort-by-scores} is
Luc Teirlinck's avatar
Luc Teirlinck committed
377
@code{nil}, Apropos lists the symbols found in alphabetical order.
Dave Love's avatar
#  
Dave Love committed
378 379 380 381 382 383 384 385 386 387

@node Library Keywords
@section Keyword Search for Lisp Libraries

@kindex C-h p
@findex finder-by-keyword
The @kbd{C-h p} command lets you search the standard Emacs Lisp
libraries by topic keywords.  Here is a partial list of keywords you can
use:

388 389
@multitable {emulations} {aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa}
@item abbrev@tab abbreviation handling, typing shortcuts, macros.
Juri Linkov's avatar
Juri Linkov committed
390 391
@item bib@tab code related to the @code{bib} bibliography processor.
@item c@tab support for the C language and related languages.
392 393
@item calendar@tab calendar and time management support.
@item comm@tab communications, networking, remote access to files.
Juri Linkov's avatar
Juri Linkov committed
394
@item convenience@tab convenience features for faster editing.
395 396 397 398
@item data@tab support for editing files of data.
@item docs@tab support for Emacs documentation.
@item emulations@tab emulations of other editors.
@item extensions@tab Emacs Lisp language extensions.
Juri Linkov's avatar
Juri Linkov committed
399 400
@item faces@tab support for multiple fonts.
@item files@tab support for editing and manipulating files.
401 402 403 404
@item frames@tab support for Emacs frames and window systems.
@item games@tab games, jokes and amusements.
@item hardware@tab support for interfacing with exotic hardware.
@item help@tab support for on-line help systems.
Juri Linkov's avatar
Juri Linkov committed
405
@item hypermedia@tab support for links between text or other media types.
406 407 408
@item i18n@tab internationalization and alternate character-set support.
@item internal@tab code for Emacs internals, build process, defaults.
@item languages@tab specialized modes for editing programming languages.
Juri Linkov's avatar
Juri Linkov committed
409 410
@item lisp@tab Lisp support, including Emacs Lisp.
@item local@tab code local to your site.
411 412
@item maint@tab maintenance aids for the Emacs development group.
@item mail@tab modes for electronic-mail handling.
Juri Linkov's avatar
Juri Linkov committed
413 414 415
@item matching@tab various sorts of searching and matching.
@item mouse@tab mouse support.
@item multimedia@tab images and sound support.
416 417
@item news@tab support for netnews reading and posting.
@item oop@tab support for object-oriented programming.
Juri Linkov's avatar
Juri Linkov committed
418
@item outlines@tab support for hierarchical outlining.
419 420
@item processes@tab process, subshell, compilation, and job control support.
@item terminals@tab support for terminal types.
Juri Linkov's avatar
Juri Linkov committed
421
@item tex@tab supporting code for the @TeX{} formatter.
422
@item tools@tab programming tools.
Juri Linkov's avatar
Juri Linkov committed
423
@item unix@tab front-ends/assistants for, or emulators of, UNIX-like features.
424 425
@item wp@tab word processing.
@end multitable
Dave Love's avatar
#  
Dave Love committed
426 427 428 429 430

@node Language Help
@section Help for International Language Support

  You can use the command @kbd{C-h L}
431 432 433 434 435 436
(@code{describe-language-environment}) to find out information about
the support for a specific language environment.  @xref{Language
Environments}.  This tells you which languages this language
environment is useful for, and lists the character sets, coding
systems, and input methods that go with it.  It also shows some sample
text to illustrate scripts.
Dave Love's avatar
#  
Dave Love committed
437 438 439 440 441 442 443 444 445 446 447 448 449 450 451

  The command @kbd{C-h h} (@code{view-hello-file}) displays the file
@file{etc/HELLO}, which shows how to say ``hello'' in many languages.

  The command @kbd{C-h I} (@code{describe-input-method}) describes
information about input methods---either a specified input method, or by
default the input method in use.  @xref{Input Methods}.

  The command @kbd{C-h C} (@code{describe-coding-system}) describes
information about coding systems---either a specified coding system, or
the ones currently in use.  @xref{Coding Systems}.

@node Help Mode
@section Help Mode Commands

Eli Zaretskii's avatar
Eli Zaretskii committed
452 453
  Help buffers provide the same commands as View mode (@pxref{Misc File
Ops}), plus a few special commands of their own.
Dave Love's avatar
#  
Dave Love committed
454 455 456 457 458

@table @kbd
@item @key{SPC}
Scroll forward.
@item @key{DEL}
459 460 461
@itemx @key{BS}
Scroll backward.  On some keyboards, this key is known as @key{BS} or
@key{backspace}.
Dave Love's avatar
#  
Dave Love committed
462 463 464 465 466 467
@item @key{RET}
Follow a cross reference at point.
@item @key{TAB}
Move point forward to the next cross reference.
@item S-@key{TAB}
Move point back to the previous cross reference.
468 469
@item Mouse-1
@itemx Mouse-2
Dave Love's avatar
#  
Dave Love committed
470 471 472
Follow a cross reference that you click on.
@end table

473
  When a function name (@pxref{M-x,, Running Commands by Name}) or
Dave Love's avatar
#  
Dave Love committed
474
variable name (@pxref{Variables}) appears in the documentation, it
475 476 477 478
normally appears inside paired single-quotes.  You can click on the
name with @kbd{Mouse-1} or @kbd{Mouse-2}, or move point there and type
@key{RET}, to view the documentation of that command or variable.  Use
@kbd{C-c C-b} to retrace your steps.
Dave Love's avatar
#  
Dave Love committed
479

480 481 482 483 484
@cindex URL, viewing in help
@cindex help, viewing web pages
@cindex viewing web pages in help
@cindex web pages, viewing in help
@findex browse-url
Bill Wohler's avatar
Bill Wohler committed
485
  You can follow cross references to URLs (web pages) as well.  When
486 487 488 489
you follow a cross reference that is a URL, the @code{browse-url}
command is used to view the web page in a browser of your choosing.
@xref{Browse-URL}.

Dave Love's avatar
#  
Dave Love committed
490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508
@kindex @key{TAB} @r{(Help mode)}
@findex help-next-ref
@kindex S-@key{TAB} @r{(Help mode)}
@findex help-previous-ref
  There are convenient commands for moving point to cross references in
the help text.  @key{TAB} (@code{help-next-ref}) moves point down to the
next cross reference.  Use @kbd{S-@key{TAB}} to move point up to the
previous cross reference (@code{help-previous-ref}).

@node Misc Help
@section Other Help Commands

@kindex C-h i
@findex info
@cindex Info
@cindex manuals, on-line
@cindex on-line manuals
  @kbd{C-h i} (@code{info}) runs the Info program, which is used for
browsing through structured documentation files.  The entire Emacs manual
Eli Zaretskii's avatar
Eli Zaretskii committed
509
is available within Info.  Eventually all the documentation of the GNU
Dave Love's avatar
#  
Dave Love committed
510 511 512
system will be available.  Type @kbd{h} after entering Info to run
a tutorial on using Info.

513
@cindex find Info manual by its file name
514 515 516 517 518 519
  With a numeric argument, @kbd{C-h i} selects an Info buffer with the
number appended to the default @samp{*info*} buffer name
(e.g. @samp{*info*<2>}).  This is useful if you want to browse
multiple Info manuals simultaneously.  If you specify just @kbd{C-u}
as the prefix argument, @kbd{C-h i} prompts for the name of a
documentation file.  This way, you can browse a file which doesn't
Dave Love's avatar
#  
Dave Love committed
520
have an entry in the top-level Info menu.  It is also handy when you
521 522
need to get to the documentation quickly, and you know the exact name
of the file.
Dave Love's avatar
#  
Dave Love committed
523

524 525
@kindex C-h F
@kindex C-h K
Dave Love's avatar
#  
Dave Love committed
526 527
@findex Info-goto-emacs-key-command-node
@findex Info-goto-emacs-command-node
528 529 530 531 532 533 534
  There are two special help commands for accessing Emacs
documentation through Info.  @kbd{C-h F @var{function} @key{RET}}
enters Info and goes straight to the documentation of the Emacs
function @var{function}.  @kbd{C-h K @var{key}} enters Info and goes
straight to the documentation of the key @var{key}.  These two keys
run the commands @code{Info-goto-emacs-command-node} and
@code{Info-goto-emacs-key-command-node}.  You can use @kbd{C-h K} to
535
find the documentation of a menu item: just select that menu item when
536
@kbd{C-h K} prompts for a key.
537

538 539 540 541
  @kbd{C-h F} and @kbd{C-h K} know about commands and keys described
in manuals other than the Emacs manual.  Thus, they make it easier to
find the documentation of commands and keys when you are not sure
which manual describes them, like when using some specialized mode.
Dave Love's avatar
#  
Dave Love committed
542

543 544 545 546 547 548 549
@kindex C-h S
@findex info-lookup-symbol
  When editing a program, if you have an Info version of the manual
for the programming language, you can use the command @kbd{C-h S}
(@code{info-lookup-symbol}) to refer to the manual documentation for a
symbol (keyword, function or variable).  The details of how this
command works depend on the major mode.
Dave Love's avatar
#  
Dave Love committed
550 551 552 553

@kindex C-h l
@findex view-lossage
  If something surprising happens, and you are not sure what commands you
554
typed, use @kbd{C-h l} (@code{view-lossage}).  @kbd{C-h l} displays the last
Dave Love's avatar
#  
Dave Love committed
555 556 557
100 command characters you typed in.  If you see commands that you don't
know, you can use @kbd{C-h c} to find out what they do.

558 559 560 561 562 563
@kindex C-h e
@findex view-echo-area-messages
  To review messages that recently appeared in the echo area, use
@kbd{C-h e} (@code{view-echo-area-messages}).  This displays the
buffer @code{*Messages*}, where those messages are kept.

Dave Love's avatar
#  
Dave Love committed
564 565 566 567
@kindex C-h m
@findex describe-mode
  Emacs has numerous major modes, each of which redefines a few keys and
makes a few other changes in how editing works.  @kbd{C-h m}
568
(@code{describe-mode}) displays documentation on the current major mode,
Dave Love's avatar
#  
Dave Love committed
569 570 571 572 573 574 575 576
which normally describes all the commands that are changed in this
mode.

@kindex C-h b
@findex describe-bindings
  @kbd{C-h b} (@code{describe-bindings}) and @kbd{C-h s}
(@code{describe-syntax}) present other information about the current
Emacs mode.  @kbd{C-h b} displays a list of all the key bindings now in
577
effect, showing the local bindings defined by the current minor modes first,
Dave Love's avatar
#  
Dave Love committed
578 579 580 581 582 583 584 585 586 587 588
then the local bindings defined by the current major mode, and finally
the global bindings (@pxref{Key Bindings}).  @kbd{C-h s} displays the
contents of the syntax table, with explanations of each character's
syntax (@pxref{Syntax}).

  You can get a similar list for a particular prefix key by typing
@kbd{C-h} after the prefix key.  (There are a few prefix keys for which
this does not work---those that provide their own bindings for
@kbd{C-h}.  One of these is @key{ESC}, because @kbd{@key{ESC} C-h} is
actually @kbd{C-M-h}, which marks a defun.)

589 590 591 592 593 594 595 596
@node Help Files
@section Help Files

  The Emacs help commands described above display the state of data
bases within Emacs.  Emacs has a few other help commands that display
pre-written help files.  These commands all have the form @kbd{C-h
C-@var{char}}; that is, @kbd{C-h} followed by a control character.

Dave Love's avatar
#  
Dave Love committed
597 598 599 600
@kindex C-h C-c
@findex describe-copying
@kindex C-h C-d
@findex describe-distribution
601 602 603 604 605 606
@kindex C-h C-e
@findex view-emacs-problems
@kindex C-h C-f
@findex view-emacs-FAQ
@kindex C-h C-n
@findex view-emacs-news
Dave Love's avatar
#  
Dave Love committed
607 608
@kindex C-h C-p
@findex describe-project
609 610 611 612
@kindex C-h C-t
@findex view-emacs-todo
@kindex C-h C-w
@findex describe-no-warranty
613
  The other @kbd{C-h} options display various files containing useful
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
information.

@table @kbd
@item C-h C-c
Displays the Emacs copying conditions (@code{describe-copying}).
These are the rules under which you can copy and redistribute Emacs.
@item C-h C-d
Displays information on how to download or order the latest version of
Emacs and other GNU software (@code{describe-distribution}).
@item C-h C-e
Displays the list of known Emacs problems, sometimes with suggested
workarounds (@code{view-emacs-problems}).
@item C-h C-f
Displays the Emacs frequently-answered-questions list (@code{view-emacs-FAQ}).
@item C-h C-n
Displays the Emacs ``news'' file, which lists new Emacs features, most
recent first (@code{view-emacs-news}).
@item C-h C-p
Displays general information about the GNU Project
(@code{describe-project}).
@item C-h C-t
Displays the Emacs to-do list (@code{view-todo}).
@item C-h C-w
Displays the full details on the complete absence of warranty for GNU
Emacs (@code{describe-no-warranty}).
@end table
Dave Love's avatar
Dave Love committed
640 641 642 643 644

@node Help Echo
@section Help on Active Text and Tooltips

@cindex tooltips
645
@cindex balloon help
Richard M. Stallman's avatar
Richard M. Stallman committed
646
  When a region of text is ``active,'' so that you can select it with
Richard M. Stallman's avatar
Richard M. Stallman committed
647
the mouse or a key like @kbd{RET}, it often has associated help text.
648 649
Areas of the mode line are examples.  On most window systems, the help
text is displayed as a ``tooltip'' (sometimes known as ``balloon
650 651 652 653
help''), when you move the mouse over the active text.  @xref{Tooltips}.
On some systems, it is shown in the echo area.  On text-only
terminals, Emacs may not be able to follow the mouse and hence will
not show the help text on mouse-over.
654 655 656 657 658 659 660 661 662 663

@kindex C-h .
@findex display-local-help
@vindex help-at-pt-display-when-idle
  You can also access text region help info using the keyboard.  The
command @kbd{C-h .} (@code{display-local-help}) displays any help text
associated with the text at point, using the echo area.  If you want
help text to be displayed automatically whenever it is available at
point, set the variable @code{help-at-pt-display-when-idle} to
@code{t}.
Miles Bader's avatar
Miles Bader committed
664 665 666 667

@ignore
   arch-tag: 6f33ab62-bc75-4367-8057-fd67cc15c3a1
@end ignore