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8cf51b2c | 1 | @c This is part of the Emacs manual. |
73b0cd50 | 2 | @c Copyright (C) 1985-1987, 1993-1995, 1997, 2000-2011 |
8838673e | 3 | @c Free Software Foundation, Inc. |
8cf51b2c GM |
4 | @c See file emacs.texi for copying conditions. |
5 | @node Help, Mark, M-x, Top | |
6 | @chapter Help | |
7 | @kindex Help | |
8 | @cindex help | |
9 | @cindex self-documentation | |
10 | @findex help-command | |
11 | @kindex C-h | |
12 | @kindex F1 | |
13 | ||
14 | Emacs provides extensive help features, all accessible through the | |
15 | @dfn{help character}, @kbd{C-h}. This is a prefix key that is used | |
16 | for commands that display documentation; the next character you type | |
9de15963 | 17 | should be a @dfn{help option}, to ask for a particular kind of help. |
8cf51b2c GM |
18 | You can cancel the @kbd{C-h} command with @kbd{C-g}. The function key |
19 | @key{F1} is equivalent to @kbd{C-h}. | |
20 | ||
21 | @kindex C-h C-h | |
22 | @findex help-for-help | |
23 | @kbd{C-h} itself is one of the help options; @kbd{C-h C-h} displays | |
24 | a list of help options, with a brief description of each one | |
25 | (@code{help-for-help}). You can scroll the list with @key{SPC} and | |
26 | @key{DEL}, then type the help option you want. To cancel, type | |
27 | @kbd{C-g}. | |
28 | ||
29 | @kbd{C-h} or @key{F1} means ``help'' in various other contexts as | |
30 | well. For instance, you can type them after a prefix key to display | |
9de15963 | 31 | a list of the keys that can follow the prefix key. (A few prefix keys |
8cf51b2c GM |
32 | don't support @kbd{C-h} in this way, because they define other |
33 | meanings for it, but they all support @key{F1} for help.) | |
34 | ||
35 | Most help buffers use a special major mode, Help mode, which lets | |
36 | you scroll conveniently with @key{SPC} and @key{DEL}. You can also | |
37 | follow hyperlinks to URLs, and to other facilities including Info | |
38 | nodes and customization buffers. @xref{Help Mode}. | |
39 | ||
40 | @cindex searching documentation efficiently | |
41 | @cindex looking for a subject in documentation | |
42 | If you are looking for a certain feature, but don't know what it is | |
43 | called or where to look, we recommend three methods. First, try an | |
44 | apropos command, then try searching the manual index, then look in the | |
45 | FAQ and the package keywords. | |
46 | ||
47 | @table @kbd | |
48 | @item C-h a @var{topics} @key{RET} | |
49 | This searches for commands whose names match the argument | |
50 | @var{topics}. The argument can be a keyword, a list of keywords, or a | |
9de15963 | 51 | regular expression (@pxref{Regexps}). @xref{Apropos}. |
8cf51b2c GM |
52 | |
53 | @item C-h i d m emacs @key{RET} i @var{topic} @key{RET} | |
54 | This searches for @var{topic} in the indices of the on-line Emacs | |
55 | manual, and displays the first match found. Press @kbd{,} to see | |
56 | subsequent matches. You can use a regular expression as @var{topic}. | |
57 | ||
58 | @item C-h i d m emacs @key{RET} s @var{topic} @key{RET} | |
59 | Similar, but searches the @emph{text} of the manual rather than the | |
60 | indices. | |
61 | ||
62 | @item C-h C-f | |
63 | This displays the Emacs FAQ. You can use the Info commands | |
64 | to browse it. | |
65 | ||
66 | @item C-h p | |
67 | This displays the available Emacs packages based on keywords. | |
68 | @xref{Library Keywords}. | |
69 | @end table | |
70 | ||
71 | @menu | |
8838673e GM |
72 | * Help Summary:: Brief list of all Help commands. |
73 | * Key Help:: Asking what a key does in Emacs. | |
74 | * Name Help:: Asking about a command, variable or function name. | |
75 | * Apropos:: Asking what pertains to a given topic. | |
8cf51b2c | 76 | * Help Mode:: Special features of Help mode and Help buffers. |
8838673e | 77 | * Library Keywords:: Finding Lisp libraries by keywords (topics). |
8cf51b2c | 78 | * Language Help:: Help relating to international language support. |
8838673e | 79 | * Misc Help:: Other help commands. |
8cf51b2c | 80 | * Help Files:: Commands to display pre-written help files. |
dad70f66 | 81 | * Help Echo:: Help on active text and tooltips (`balloon help'). |
8cf51b2c GM |
82 | @end menu |
83 | ||
84 | @iftex | |
85 | @node Help Summary | |
86 | @end iftex | |
87 | @ifnottex | |
88 | @node Help Summary | |
89 | @section Help Summary | |
90 | @end ifnottex | |
91 | ||
92 | Here is a summary of the Emacs interactive help commands. (The | |
9de15963 MR |
93 | character that follows @kbd{C-h} is the ``help option.'') See |
94 | @ref{Help Files}, for other help commands that display fixed files | |
95 | of information. | |
8cf51b2c GM |
96 | |
97 | @table @kbd | |
98 | @item C-h a @var{topics} @key{RET} | |
99 | Display a list of commands whose names match @var{topics} | |
100 | (@code{apropos-command}; @pxref{Apropos}). | |
101 | @item C-h b | |
102 | Display all active key bindings; minor mode bindings first, then those | |
103 | of the major mode, then global bindings (@code{describe-bindings}). | |
104 | @item C-h c @var{key} | |
105 | Given a key sequence @var{key}, show the name of the command that it | |
106 | runs (@code{describe-key-briefly}). Here @kbd{c} stands for | |
107 | ``character.'' For more extensive information on @var{key}, use | |
108 | @kbd{C-h k}. | |
109 | @item C-h d @var{topics} @key{RET} | |
110 | Display the commands and variables whose documentation matches | |
111 | @var{topics} (@code{apropos-documentation}). | |
112 | @item C-h e | |
113 | Display the @code{*Messages*} buffer | |
114 | (@code{view-echo-area-messages}). | |
115 | @item C-h f @var{function} @key{RET} | |
116 | Display documentation on the Lisp function named @var{function} | |
117 | (@code{describe-function}). Since commands are Lisp functions, | |
118 | this works for commands too. | |
119 | @item C-h h | |
120 | Display the @file{HELLO} file, which shows examples of various character | |
121 | sets. | |
122 | @item C-h i | |
123 | Run Info, the GNU documentation browser (@code{info}). | |
124 | The complete Emacs manual is available on-line in Info. | |
125 | @item C-h k @var{key} | |
126 | Display the name and documentation of the command that @var{key} runs | |
127 | (@code{describe-key}). | |
128 | @item C-h l | |
9de15963 | 129 | Display a description of your last 300 keystrokes |
8cf51b2c GM |
130 | (@code{view-lossage}). |
131 | @item C-h m | |
132 | Display documentation of the current major mode (@code{describe-mode}). | |
9de15963 MR |
133 | @item C-h n |
134 | Display news of recent Emacs changes (@code{view-emacs-news}). | |
8cf51b2c | 135 | @item C-h p |
98932641 GM |
136 | Find packages by topic keyword (@code{finder-by-keyword}). For an |
137 | alternative interface to the same information, try the @code{info-finder} | |
138 | command. | |
9de15963 MR |
139 | @item C-h r |
140 | Display the Emacs manual in Info (@code{info-emacs-manual}). | |
8cf51b2c GM |
141 | @item C-h s |
142 | Display the current contents of the syntax table, with an explanation of | |
143 | what they mean (@code{describe-syntax}). @xref{Syntax}. | |
144 | @item C-h t | |
145 | Enter the Emacs interactive tutorial (@code{help-with-tutorial}). | |
146 | @item C-h v @var{var} @key{RET} | |
147 | Display the documentation of the Lisp variable @var{var} | |
148 | (@code{describe-variable}). | |
149 | @item C-h w @var{command} @key{RET} | |
150 | Show which keys run the command named @var{command} (@code{where-is}). | |
151 | @item C-h C @var{coding} @key{RET} | |
152 | Describe the coding system @var{coding} | |
153 | (@code{describe-coding-system}). | |
154 | @item C-h C @key{RET} | |
155 | Describe the coding systems currently in use. | |
9de15963 MR |
156 | @item C-h F @var{command} @key{RET} |
157 | Enter Info and go to the node that documents the Emacs command | |
158 | @var{command} (@code{Info-goto-emacs-command-node}). | |
8cf51b2c GM |
159 | @item C-h I @var{method} @key{RET} |
160 | Describe the input method @var{method} (@code{describe-input-method}). | |
9de15963 MR |
161 | @item C-h K @var{key} |
162 | Enter Info and go to the node that documents the key sequence | |
163 | @var{key} (@code{Info-goto-emacs-key-command-node}). | |
8cf51b2c GM |
164 | @item C-h L @var{language-env} @key{RET} |
165 | Display information on the character sets, coding systems, and input | |
166 | methods used in language environment @var{language-env} | |
167 | (@code{describe-language-environment}). | |
8cf51b2c GM |
168 | @item C-h S @var{symbol} @key{RET} |
169 | Display the Info documentation on symbol @var{symbol} according to the | |
170 | programming language you are editing (@code{info-lookup-symbol}). | |
171 | @item C-h . | |
172 | Display the help message for a special text area, if point is in one | |
173 | (@code{display-local-help}). (These include, for example, links in | |
174 | @samp{*Help*} buffers.) | |
175 | @end table | |
176 | ||
177 | @node Key Help | |
178 | @section Documentation for a Key | |
179 | ||
180 | @kindex C-h c | |
181 | @findex describe-key-briefly | |
182 | The help commands to get information about a key sequence are | |
183 | @kbd{C-h c} and @w{@kbd{C-h k}}. @kbd{C-h c @var{key}} displays in | |
184 | the echo area the name of the command that @var{key} is bound to. For | |
185 | example, @kbd{C-h c C-f} displays @samp{forward-char}. Since command | |
186 | names are chosen to describe what the commands do, this gives you a | |
187 | very brief description of what @var{key} does. | |
188 | ||
189 | @kindex C-h k | |
190 | @findex describe-key | |
191 | @kbd{C-h k @var{key}} is similar but gives more information: it | |
192 | displays the documentation string of the command as well as its name. | |
193 | It displays this information in a window, since it may not fit in the | |
194 | echo area. | |
195 | ||
196 | @kindex C-h K | |
197 | @findex Info-goto-emacs-key-command-node | |
198 | To find the documentation of a key sequence @var{key}, type @kbd{C-h | |
199 | K @var{key}}. This displays the appropriate manual section which | |
200 | contains the documentation of @var{key}. | |
201 | ||
202 | @kbd{C-h c}, @kbd{C-h k} and @kbd{C-h K} work for any sort of key | |
203 | sequences, including function keys, menus, and mouse events. For | |
204 | instance, after @kbd{C-h k} you can select a menu item from the menu | |
205 | bar, to view the documentation string of the command it runs. | |
206 | ||
207 | @kindex C-h w | |
208 | @findex where-is | |
209 | @kbd{C-h w @var{command} @key{RET}} lists the keys that are bound to | |
210 | @var{command}. It displays the list in the echo area. If it says the | |
211 | command is not on any key, that means you must use @kbd{M-x} to run | |
212 | it. @kbd{C-h w} runs the command @code{where-is}. | |
213 | ||
214 | @node Name Help | |
215 | @section Help by Command or Variable Name | |
216 | ||
217 | @kindex C-h f | |
218 | @findex describe-function | |
219 | @kbd{C-h f @var{function} @key{RET}} (@code{describe-function}) | |
220 | displays the documentation of Lisp function @var{function}, in a | |
221 | window. Since commands are Lisp functions, you can use this method to | |
222 | view the documentation of any command whose name you know. For | |
223 | example, | |
224 | ||
225 | @example | |
226 | C-h f auto-fill-mode @key{RET} | |
227 | @end example | |
228 | ||
229 | @noindent | |
230 | displays the documentation of @code{auto-fill-mode}. This is the only | |
231 | way to get the documentation of a command that is not bound to any key | |
232 | (one which you would normally run using @kbd{M-x}). | |
233 | ||
234 | @kbd{C-h f} is also useful for Lisp functions that you use in a Lisp | |
235 | program. For example, if you have just written the expression | |
236 | @code{(make-vector len)} and want to check that you are using | |
237 | @code{make-vector} properly, type @kbd{C-h f make-vector @key{RET}}. | |
238 | Because @kbd{C-h f} allows all function names, not just command names, | |
239 | you may find that some of your favorite completion abbreviations that | |
240 | work in @kbd{M-x} don't work in @kbd{C-h f}. An abbreviation that is | |
241 | unique among command names may not be unique among all function names. | |
242 | ||
243 | If you type @kbd{C-h f @key{RET}}, it describes the function called | |
244 | by the innermost Lisp expression in the buffer around point, | |
245 | @emph{provided} that function name is a valid, defined Lisp function. | |
246 | (That name appears as the default while you enter the argument.) For | |
247 | example, if point is located following the text @samp{(make-vector | |
248 | (car x)}, the innermost list containing point is the one that starts | |
249 | with @samp{(make-vector}, so @kbd{C-h f @key{RET}} will describe the | |
250 | function @code{make-vector}. | |
251 | ||
252 | @kbd{C-h f} is also useful just to verify that you spelled a | |
253 | function name correctly. If the minibuffer prompt for @kbd{C-h f} | |
254 | shows the function name from the buffer as the default, it means that | |
255 | name is defined as a Lisp function. Type @kbd{C-g} to cancel the | |
256 | @kbd{C-h f} command if you don't really want to view the | |
257 | documentation. | |
258 | ||
259 | @kindex C-h v | |
260 | @findex describe-variable | |
261 | @kbd{C-h v} (@code{describe-variable}) is like @kbd{C-h f} but | |
262 | describes Lisp variables instead of Lisp functions. Its default is | |
263 | the Lisp symbol around or before point, if that is the name of a | |
264 | defined Lisp variable. @xref{Variables}. | |
265 | ||
266 | Help buffers that describe Emacs variables and functions normally | |
267 | have hyperlinks to the corresponding source definition, if you have | |
268 | the source files installed. (@xref{Hyperlinking}.) If you know Lisp | |
269 | (or C), this provides the ultimate documentation. If you don't know | |
270 | Lisp, you should learn it. (The Introduction to Emacs Lisp | |
271 | Programming, available from the FSF through fsf.org, is a good way to | |
272 | get started.) If Emacs feels you are just @emph{using} it, treating | |
273 | it as an object program, its feelings may be hurt. For real intimacy, | |
274 | read the Emacs source code. | |
275 | ||
276 | @kindex C-h F | |
277 | @findex Info-goto-emacs-command-node | |
9de15963 | 278 | To find a command's documentation in a manual, use @kbd{C-h F} |
8cf51b2c GM |
279 | (@code{Info-goto-emacs-command-node}). This knows about various |
280 | manuals, not just the Emacs manual, and finds the right one. | |
281 | ||
282 | @node Apropos | |
283 | @section Apropos | |
284 | ||
285 | The @dfn{apropos} commands answer questions like, ``What are the | |
286 | commands for working with files?'' More precisely, you specify an | |
287 | @dfn{apropos pattern}, which means either a word, a list of words, or | |
288 | a regular expression. Each apropos command displays a list of items | |
289 | that match the pattern, in a separate buffer. | |
290 | ||
291 | @table @kbd | |
292 | @item C-h a @var{pattern} @key{RET} | |
293 | Search for commands whose names match @var{pattern}. | |
294 | ||
295 | @item M-x apropos @key{RET} @var{pattern} @key{RET} | |
296 | Search for functions and variables whose names match @var{pattern}. | |
297 | Both interactive functions (commands) and noninteractive functions can | |
298 | be found by this command. | |
299 | ||
300 | @item M-x apropos-variable @key{RET} @var{pattern} @key{RET} | |
301 | Search for user-option variables whose names match @var{pattern}. | |
302 | ||
303 | @item M-x apropos-value @key{RET} @var{pattern} @key{RET} | |
ff98e024 MR |
304 | Search for functions whose definitions match @var{pattern}, and |
305 | variables whose values match @var{pattern}. | |
8cf51b2c GM |
306 | |
307 | @item C-h d @var{pattern} @key{RET} | |
308 | Search for functions and variables whose @strong{documentation | |
309 | strings} match @var{pattern}. | |
310 | @end table | |
311 | ||
312 | @kindex C-h a | |
313 | @findex apropos-command | |
314 | @cindex apropos | |
315 | The simplest kind of apropos pattern is one word. Anything which | |
316 | contains that word matches the pattern. Thus, to find the commands | |
317 | that work on files, type @kbd{C-h a file @key{RET}}. This displays a | |
318 | list of all command names that contain @samp{file}, including | |
319 | @code{copy-file}, @code{find-file}, and so on. Each command name | |
320 | comes with a brief description and a list of keys you can currently | |
321 | invoke it with. In our example, it would say that you can invoke | |
322 | @code{find-file} by typing @kbd{C-x C-f}. | |
323 | ||
324 | The @kbd{a} in @kbd{C-h a} stands for ``Apropos''; @kbd{C-h a} | |
325 | runs the command @code{apropos-command}. This command normally checks | |
326 | only commands (interactive functions); if you specify a prefix | |
327 | argument, it checks noninteractive functions as well. | |
328 | ||
329 | For more information about a function definition, variable or symbol | |
330 | property listed in the apropos buffer, you can click on it with | |
331 | @kbd{Mouse-1} or @kbd{Mouse-2}, or move there and type @key{RET}. | |
332 | ||
333 | When you specify more than one word in the apropos pattern, a name | |
334 | must contain at least two of the words in order to match. Thus, if | |
335 | you are looking for commands to kill a chunk of text before point, you | |
336 | could try @kbd{C-h a kill back backward behind before @key{RET}}. The | |
337 | real command name @code{kill-backward} will match that; if there were | |
338 | a command @code{kill-text-before}, it would also match, since it | |
339 | contains two of the specified words. | |
340 | ||
341 | For even greater flexibility, you can specify a regular expression | |
342 | (@pxref{Regexps}). An apropos pattern is interpreted as a regular | |
343 | expression if it contains any of the regular expression special | |
344 | characters, @samp{^$*+?.\[}. | |
345 | ||
346 | Following the conventions for naming Emacs commands, here are some | |
347 | words that you'll find useful in apropos patterns. By using them in | |
348 | @kbd{C-h a}, you will also get a feel for the naming conventions. | |
349 | ||
350 | @quotation | |
351 | char, line, word, sentence, paragraph, region, page, sexp, list, defun, | |
352 | rect, buffer, frame, window, face, file, dir, register, mode, beginning, end, | |
353 | forward, backward, next, previous, up, down, search, goto, kill, delete, | |
354 | mark, insert, yank, fill, indent, case, change, set, what, list, find, | |
355 | view, describe, default. | |
356 | @end quotation | |
357 | ||
358 | @findex apropos | |
359 | Use @kbd{M-x apropos} instead of @kbd{C-h a} to list all the Lisp | |
360 | symbols that match an apropos pattern, not just the symbols that are | |
361 | commands. This command does not list key bindings by default; specify | |
362 | a numeric argument if you want it to list them. | |
363 | ||
364 | @findex apropos-variable | |
365 | Use @kbd{M-x apropos-variable} to list user-customizable variables | |
366 | that match an apropos pattern. If you specify a prefix argument, it | |
367 | lists all matching variables. | |
368 | ||
369 | @kindex C-h d | |
370 | @findex apropos-documentation | |
371 | The @code{apropos-documentation} command is like @code{apropos} | |
372 | except that it searches documentation strings instead of symbol names | |
373 | for matches. | |
374 | ||
375 | @findex apropos-value | |
376 | The @code{apropos-value} command is like @code{apropos} except that | |
377 | it searches variables' values for matches for the apropos pattern. | |
378 | With a prefix argument, it also checks symbols' function definitions | |
379 | and property lists. | |
380 | ||
381 | @vindex apropos-do-all | |
382 | If the variable @code{apropos-do-all} is non-@code{nil}, the apropos | |
383 | commands always behave as if they had been given a prefix argument. | |
384 | ||
385 | @vindex apropos-sort-by-scores | |
386 | @cindex apropos search results, order by score | |
387 | By default, apropos lists the search results in alphabetical order. | |
388 | If the variable @code{apropos-sort-by-scores} is non-@code{nil}, the | |
389 | apropos commands try to guess the relevance of each result, and | |
390 | display the most relevant ones first. | |
391 | ||
392 | @vindex apropos-documentation-sort-by-scores | |
393 | By default, apropos lists the search results for | |
394 | @code{apropos-documentation} in order of relevance of the match. If | |
395 | the variable @code{apropos-documentation-sort-by-scores} is | |
396 | @code{nil}, apropos lists the symbols found in alphabetical order. | |
397 | ||
398 | @node Help Mode | |
399 | @section Help Mode Commands | |
400 | ||
401 | Help buffers provide the same commands as View mode (@pxref{Misc File | |
402 | Ops}), plus a few special commands of their own. | |
403 | ||
404 | @table @kbd | |
405 | @item @key{SPC} | |
406 | Scroll forward. | |
407 | @item @key{DEL} | |
408 | Scroll backward. | |
409 | @item @key{RET} | |
410 | Follow a cross reference at point. | |
411 | @item @key{TAB} | |
412 | Move point forward to the next cross reference. | |
413 | @item S-@key{TAB} | |
414 | Move point back to the previous cross reference. | |
415 | @item Mouse-1 | |
416 | @itemx Mouse-2 | |
417 | Follow a cross reference that you click on. | |
418 | @item C-c C-c | |
419 | Show all documentation about the symbol at point. | |
420 | @end table | |
421 | ||
422 | When a function name (@pxref{M-x,, Running Commands by Name}), | |
423 | variable name (@pxref{Variables}), or face name (@pxref{Faces}) | |
424 | appears in the documentation, it normally appears inside paired | |
425 | single-quotes. To view the documentation of that command, variable or | |
426 | face, you can click on the name with @kbd{Mouse-1} or @kbd{Mouse-2}, | |
427 | or move point there and type @key{RET}. Use @kbd{C-c C-b} to retrace | |
428 | your steps. | |
429 | ||
430 | @cindex URL, viewing in help | |
431 | @cindex help, viewing web pages | |
432 | @cindex viewing web pages in help | |
433 | @cindex web pages, viewing in help | |
434 | @findex browse-url | |
435 | You can follow cross references to URLs (web pages) also. This uses | |
436 | the @code{browse-url} command to view the page in the browser you | |
437 | choose. @xref{Browse-URL}. | |
438 | ||
439 | @kindex @key{TAB} @r{(Help mode)} | |
440 | @findex help-next-ref | |
441 | @kindex S-@key{TAB} @r{(Help mode)} | |
442 | @findex help-previous-ref | |
443 | There are convenient commands to move point to cross references in | |
444 | the help text. @key{TAB} (@code{help-next-ref}) moves point down to | |
445 | the next cross reference. @kbd{S-@key{TAB}} moves up to the previous | |
446 | cross reference (@code{help-previous-ref}). | |
447 | ||
448 | To view all documentation about any symbol name that appears in the | |
449 | text, move point to the symbol name and type @kbd{C-c C-c} | |
450 | (@code{help-follow-symbol}). This shows all available documentation | |
451 | about the symbol as a variable, function and/or face. As above, use | |
452 | @kbd{C-c C-b} to retrace your steps. | |
453 | ||
454 | @node Library Keywords | |
455 | @section Keyword Search for Lisp Libraries | |
456 | ||
457 | @kindex C-h p | |
458 | @findex finder-by-keyword | |
459 | The @kbd{C-h p} command lets you search the standard Emacs Lisp | |
460 | libraries by topic keywords. Here is a partial list of keywords you can | |
461 | use: | |
462 | ||
463 | @multitable {convenience} {aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa} | |
464 | @item abbrev@tab abbreviation handling, typing shortcuts, macros. | |
465 | @item bib@tab code related to the @code{bib} bibliography processor. | |
466 | @item c@tab support for the C language and related languages. | |
467 | @item calendar@tab calendar and time management support. | |
468 | @item comm@tab communications, networking, remote access to files. | |
469 | @item convenience@tab convenience features for faster editing. | |
470 | @item data@tab support for editing files of data. | |
471 | @item docs@tab support for Emacs documentation. | |
472 | @item emulations@tab emulations of other editors. | |
473 | @item extensions@tab Emacs Lisp language extensions. | |
474 | @item faces@tab support for multiple fonts. | |
475 | @item files@tab support for editing and manipulating files. | |
476 | @item frames@tab support for Emacs frames and window systems. | |
477 | @item games@tab games, jokes and amusements. | |
478 | @item hardware@tab support for interfacing with exotic hardware. | |
479 | @item help@tab support for on-line help systems. | |
480 | @item hypermedia@tab support for links between text or other media types. | |
481 | @item i18n@tab internationalization and alternate character-set support. | |
482 | @item internal@tab code for Emacs internals, build process, defaults. | |
483 | @item languages@tab specialized modes for editing programming languages. | |
484 | @item lisp@tab Lisp support, including Emacs Lisp. | |
485 | @item local@tab code local to your site. | |
486 | @item maint@tab maintenance aids for the Emacs development group. | |
487 | @item mail@tab modes for electronic-mail handling. | |
488 | @item matching@tab various sorts of searching and matching. | |
489 | @item mouse@tab mouse support. | |
490 | @item multimedia@tab images and sound support. | |
491 | @item news@tab support for netnews reading and posting. | |
492 | @item oop@tab support for object-oriented programming. | |
493 | @item outlines@tab support for hierarchical outlining. | |
494 | @item processes@tab process, subshell, compilation, and job control support. | |
495 | @item terminals@tab support for terminal types. | |
496 | @item tex@tab supporting code for the @TeX{} formatter. | |
497 | @item tools@tab programming tools. | |
498 | @item unix@tab front-ends/assistants for, or emulators of, UNIX-like features. | |
499 | @item wp@tab word processing. | |
500 | @end multitable | |
501 | ||
502 | @node Language Help | |
503 | @section Help for International Language Support | |
504 | ||
505 | You can use the command @kbd{C-h L} | |
506 | (@code{describe-language-environment}) to get information about a | |
507 | specific language environment. @xref{Language Environments}. This | |
508 | tells you which languages this language environment supports. It also | |
509 | lists the character sets, coding systems, and input methods that work | |
510 | with this language environment, and finally shows some sample text to | |
511 | illustrate scripts. | |
512 | ||
513 | The command @kbd{C-h h} (@code{view-hello-file}) displays the file | |
514 | @file{etc/HELLO}, which shows how to say ``hello'' in many languages. | |
515 | ||
516 | The command @kbd{C-h I} (@code{describe-input-method}) describes an | |
517 | input method---either a specified input method, or by default the | |
518 | input method currently in use. @xref{Input Methods}. | |
519 | ||
520 | The command @kbd{C-h C} (@code{describe-coding-system}) describes | |
521 | coding systems---either a specified coding system, or the ones | |
522 | currently in use. @xref{Coding Systems}. | |
523 | ||
524 | @node Misc Help | |
525 | @section Other Help Commands | |
526 | ||
527 | @kindex C-h i | |
528 | @findex info | |
529 | @cindex Info | |
530 | @cindex manuals, on-line | |
531 | @cindex on-line manuals | |
532 | @kbd{C-h i} (@code{info}) runs the Info program, which browses | |
533 | structured documentation files. The entire Emacs manual is available | |
534 | within Info, along with many other manuals for the GNU system. Type | |
535 | @kbd{h} after entering Info to run a tutorial on using Info. | |
536 | ||
537 | @cindex find Info manual by its file name | |
538 | With a numeric argument @var{n}, @kbd{C-h i} selects the Info buffer | |
539 | @samp{*info*<@var{n}>}. This is useful if you want to browse multiple | |
540 | Info manuals simultaneously. If you specify just @kbd{C-u} as the | |
541 | prefix argument, @kbd{C-h i} prompts for the name of a documentation | |
542 | file, so you can browse a file which doesn't have an entry in the | |
543 | top-level Info menu. | |
544 | ||
545 | The help commands @kbd{C-h F @var{function} @key{RET}} and @kbd{C-h | |
546 | K @var{key}}, described above, enter Info and go straight to the | |
547 | documentation of @var{function} or @var{key}. | |
548 | ||
549 | @kindex C-h S | |
550 | @findex info-lookup-symbol | |
551 | When editing a program, if you have an Info version of the manual | |
552 | for the programming language, you can use @kbd{C-h S} | |
ff98e024 MR |
553 | (@code{info-lookup-symbol}) to find an entry for a symbol (keyword, |
554 | function or variable) in the proper manual. The details of how this | |
555 | command works depend on the major mode. | |
8cf51b2c GM |
556 | |
557 | @kindex C-h l | |
558 | @findex view-lossage | |
9de15963 MR |
559 | If something surprising happens, and you are not sure what you typed, |
560 | use @kbd{C-h l} (@code{view-lossage}). @kbd{C-h l} displays your last | |
561 | 300 input keystrokes. If you see commands that you don't know, you can | |
562 | use @kbd{C-h c} to find out what they do. | |
8cf51b2c GM |
563 | |
564 | @kindex C-h e | |
565 | @findex view-echo-area-messages | |
566 | To review recent echo area messages, use @kbd{C-h e} | |
567 | (@code{view-echo-area-messages}). This displays the buffer | |
568 | @code{*Messages*}, where those messages are kept. | |
569 | ||
570 | @kindex C-h m | |
571 | @findex describe-mode | |
572 | Each Emacs major mode typically redefines a few keys and makes other | |
573 | changes in how editing works. @kbd{C-h m} (@code{describe-mode}) | |
574 | displays documentation on the current major mode, which normally | |
575 | describes the commands and features that are changed in this mode. | |
576 | ||
577 | @kindex C-h b | |
578 | @findex describe-bindings | |
579 | @kbd{C-h b} (@code{describe-bindings}) and @kbd{C-h s} | |
580 | (@code{describe-syntax}) show other information about the current | |
581 | environment within Emacs. @kbd{C-h b} displays a list of all the key | |
582 | bindings now in effect: first the local bindings of the current minor | |
583 | modes, then the local bindings defined by the current major mode, and | |
584 | finally the global bindings (@pxref{Key Bindings}). @kbd{C-h s} | |
585 | displays the contents of the syntax table, with explanations of each | |
586 | character's syntax (@pxref{Syntax}). | |
587 | ||
588 | You can get a list of subcommands for a particular prefix key by | |
589 | typing @kbd{C-h} after the prefix key. (There are a few prefix keys | |
590 | for which this does not work---those that provide their own bindings | |
591 | for @kbd{C-h}. One of these is @key{ESC}, because @kbd{@key{ESC} C-h} | |
592 | is actually @kbd{C-M-h}, which marks a defun.) | |
593 | ||
594 | @node Help Files | |
595 | @section Help Files | |
596 | ||
597 | The Emacs help commands described above display dynamic help based | |
598 | on the current state within Emacs, or refer to manuals. Other help | |
087a8fdc KS |
599 | commands display pre-written, static help files. |
600 | ||
601 | Except for @kbd{C-h g}, these commands all have the form @kbd{C-h | |
602 | C-@var{char}}; that is, @kbd{C-h} followed by a control character. | |
8cf51b2c GM |
603 | |
604 | @kindex C-h C-c | |
605 | @findex describe-copying | |
606 | @kindex C-h C-d | |
087a8fdc | 607 | @findex view-emacs-debugging |
8cf51b2c | 608 | @kindex C-h C-e |
087a8fdc | 609 | @findex view-external-packages |
8cf51b2c GM |
610 | @kindex C-h C-f |
611 | @findex view-emacs-FAQ | |
087a8fdc KS |
612 | @kindex C-h g |
613 | @findex describe-gnu-project | |
614 | @kindex C-h C-m | |
615 | @findex view-order-manuals | |
8cf51b2c GM |
616 | @kindex C-h C-n |
617 | @findex view-emacs-news | |
087a8fdc KS |
618 | @kindex C-h C-o |
619 | @findex describe-distribution | |
8cf51b2c | 620 | @kindex C-h C-p |
087a8fdc | 621 | @findex view-emacs-problems |
8cf51b2c GM |
622 | @kindex C-h C-t |
623 | @findex view-emacs-todo | |
624 | @kindex C-h C-w | |
625 | @findex describe-no-warranty | |
626 | ||
627 | @table @kbd | |
628 | @item C-h C-c | |
629 | Display the Emacs copying conditions (@code{describe-copying}). | |
630 | These are the rules under which you can copy and redistribute Emacs. | |
631 | @item C-h C-d | |
087a8fdc | 632 | Display how to debug Emacs problems (@code{view-emacs-debugging}). |
8cf51b2c GM |
633 | @item C-h C-f |
634 | Display the Emacs frequently-answered-questions list (@code{view-emacs-FAQ}). | |
087a8fdc KS |
635 | @item C-h g |
636 | Display general information about the GNU Project | |
637 | (@code{describe-gnu-project}). | |
638 | @item C-h C-m | |
639 | Display how to order printed copies of Emacs manuals | |
640 | (@code{view-order-manuals}). | |
8cf51b2c GM |
641 | @item C-h C-n |
642 | Display the Emacs ``news'' file, which lists new features in the most | |
643 | recent version of Emacs (@code{view-emacs-news}). | |
087a8fdc KS |
644 | @item C-h C-o |
645 | Display how to order or download the latest version of | |
646 | Emacs and other GNU software (@code{describe-distribution}). | |
8cf51b2c | 647 | @item C-h C-p |
087a8fdc KS |
648 | Display the list of known Emacs problems, sometimes with suggested |
649 | workarounds (@code{view-emacs-problems}). | |
8cf51b2c | 650 | @item C-h C-t |
087a8fdc | 651 | Display the Emacs to-do list (@code{view-emacs-todo}). |
8cf51b2c GM |
652 | @item C-h C-w |
653 | Display the full details on the complete absence of warranty for GNU | |
654 | Emacs (@code{describe-no-warranty}). | |
655 | @end table | |
656 | ||
657 | @node Help Echo | |
658 | @section Help on Active Text and Tooltips | |
659 | ||
660 | @cindex tooltips | |
661 | @cindex balloon help | |
a67cf2bb RS |
662 | When text on the screen is ``active'', so that it does something |
663 | special in response to mouse clicks or @kbd{RET}, it often has associated | |
664 | help text. For instance, most parts of the mode line have help text. On | |
665 | terminals that support mouse tracking, Emacs displays the help text as a | |
666 | ``tooltip'' (sometimes known as ``balloon help'') or in the echo area, | |
667 | whenever you leave the mouse stationary over the active text. | |
668 | @xref{Tooltips}. | |
8cf51b2c GM |
669 | |
670 | @kindex C-h . | |
671 | @findex display-local-help | |
672 | @vindex help-at-pt-display-when-idle | |
a67cf2bb RS |
673 | If your terminal doesn't support mouse-tracking, you can display the |
674 | help text for active buffer text using the keyboard. @kbd{C-h .} | |
675 | (@code{display-local-help}) displays any help text associated with the | |
676 | character after point, using the echo area. To display help text | |
677 | automatically whenever it is available on the character after point, set | |
678 | the variable @code{help-at-pt-display-when-idle} to @code{t}. |