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8cf51b2c | 1 | @c This is part of the Emacs manual. |
73b0cd50 | 2 | @c Copyright (C) 1997, 1999-2011 Free Software Foundation, Inc. |
8cf51b2c GM |
3 | @c See file emacs.texi for copying conditions. |
4 | @node International, Major Modes, Frames, Top | |
5 | @chapter International Character Set Support | |
59eda47f RS |
6 | @c This node is referenced in the tutorial. When renaming or deleting |
7 | @c it, the tutorial needs to be adjusted. (TUTORIAL.de) | |
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8 | @cindex MULE |
9 | @cindex international scripts | |
10 | @cindex multibyte characters | |
11 | @cindex encoding of characters | |
12 | ||
13 | @cindex Celtic | |
14 | @cindex Chinese | |
15 | @cindex Cyrillic | |
16 | @cindex Czech | |
17 | @cindex Devanagari | |
18 | @cindex Hindi | |
19 | @cindex Marathi | |
20 | @cindex Ethiopic | |
21 | @cindex German | |
22 | @cindex Greek | |
23 | @cindex Hebrew | |
24 | @cindex IPA | |
25 | @cindex Japanese | |
26 | @cindex Korean | |
27 | @cindex Lao | |
28 | @cindex Latin | |
29 | @cindex Polish | |
30 | @cindex Romanian | |
31 | @cindex Slovak | |
32 | @cindex Slovenian | |
33 | @cindex Thai | |
34 | @cindex Tibetan | |
35 | @cindex Turkish | |
36 | @cindex Vietnamese | |
37 | @cindex Dutch | |
38 | @cindex Spanish | |
39 | Emacs supports a wide variety of international character sets, | |
40 | including European and Vietnamese variants of the Latin alphabet, as | |
41 | well as Cyrillic, Devanagari (for Hindi and Marathi), Ethiopic, Greek, | |
42 | Han (for Chinese and Japanese), Hangul (for Korean), Hebrew, IPA, | |
43 | Kannada, Lao, Malayalam, Tamil, Thai, Tibetan, and Vietnamese scripts. | |
44 | Emacs also supports various encodings of these characters used by | |
45 | other internationalized software, such as word processors and mailers. | |
46 | ||
47 | Emacs allows editing text with international characters by supporting | |
48 | all the related activities: | |
49 | ||
50 | @itemize @bullet | |
51 | @item | |
52 | You can visit files with non-@acronym{ASCII} characters, save non-@acronym{ASCII} text, and | |
53 | pass non-@acronym{ASCII} text between Emacs and programs it invokes (such as | |
54 | compilers, spell-checkers, and mailers). Setting your language | |
55 | environment (@pxref{Language Environments}) takes care of setting up the | |
56 | coding systems and other options for a specific language or culture. | |
57 | Alternatively, you can specify how Emacs should encode or decode text | |
58 | for each command; see @ref{Text Coding}. | |
59 | ||
60 | @item | |
61 | You can display non-@acronym{ASCII} characters encoded by the various | |
62 | scripts. This works by using appropriate fonts on graphics displays | |
63 | (@pxref{Defining Fontsets}), and by sending special codes to text-only | |
64 | displays (@pxref{Terminal Coding}). If some characters are displayed | |
65 | incorrectly, refer to @ref{Undisplayable Characters}, which describes | |
66 | possible problems and explains how to solve them. | |
67 | ||
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68 | @item |
69 | Characters from scripts whose natural ordering of text is from right | |
70 | to left are reordered for display (@pxref{Bidirectional Editing}). | |
71 | These scripts include Arabic, Hebrew, Syriac, Thaana, and a few | |
72 | others. | |
73 | ||
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74 | @item |
75 | You can insert non-@acronym{ASCII} characters or search for them. To do that, | |
76 | you can specify an input method (@pxref{Select Input Method}) suitable | |
77 | for your language, or use the default input method set up when you set | |
78 | your language environment. If | |
79 | your keyboard can produce non-@acronym{ASCII} characters, you can select an | |
80 | appropriate keyboard coding system (@pxref{Terminal Coding}), and Emacs | |
81 | will accept those characters. Latin-1 characters can also be input by | |
82 | using the @kbd{C-x 8} prefix, see @ref{Unibyte Mode}. | |
83 | ||
84 | On X Window systems, your locale should be set to an appropriate value | |
85 | to make sure Emacs interprets keyboard input correctly; see | |
86 | @ref{Language Environments, locales}. | |
87 | @end itemize | |
88 | ||
89 | The rest of this chapter describes these issues in detail. | |
90 | ||
91 | @menu | |
92 | * International Chars:: Basic concepts of multibyte characters. | |
93 | * Enabling Multibyte:: Controlling whether to use multibyte characters. | |
94 | * Language Environments:: Setting things up for the language you use. | |
95 | * Input Methods:: Entering text characters not on your keyboard. | |
96 | * Select Input Method:: Specifying your choice of input methods. | |
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97 | * Coding Systems:: Character set conversion when you read and |
98 | write files, and so on. | |
99 | * Recognize Coding:: How Emacs figures out which conversion to use. | |
100 | * Specify Coding:: Specifying a file's coding system explicitly. | |
101 | * Output Coding:: Choosing coding systems for output. | |
102 | * Text Coding:: Choosing conversion to use for file text. | |
103 | * Communication Coding:: Coding systems for interprocess communication. | |
104 | * File Name Coding:: Coding systems for file @emph{names}. | |
105 | * Terminal Coding:: Specifying coding systems for converting | |
106 | terminal input and output. | |
107 | * Fontsets:: Fontsets are collections of fonts | |
108 | that cover the whole spectrum of characters. | |
109 | * Defining Fontsets:: Defining a new fontset. | |
70bb6cac | 110 | * Modifying Fontsets:: Modifying an existing fontset. |
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111 | * Undisplayable Characters:: When characters don't display. |
112 | * Unibyte Mode:: You can pick one European character set | |
113 | to use without multibyte characters. | |
114 | * Charsets:: How Emacs groups its internal character codes. | |
f4b6ba46 | 115 | * Bidirectional Editing:: Support for right-to-left scripts. |
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116 | @end menu |
117 | ||
118 | @node International Chars | |
119 | @section Introduction to International Character Sets | |
120 | ||
121 | The users of international character sets and scripts have | |
122 | established many more-or-less standard coding systems for storing | |
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123 | files. These coding systems are typically @dfn{multibyte}, meaning |
124 | that sequences of two or more bytes are used to represent individual | |
125 | non-@acronym{ASCII} characters. | |
126 | ||
127 | @cindex Unicode | |
128 | Internally, Emacs uses its own multibyte character encoding, which | |
129 | is a superset of the @dfn{Unicode} standard. This internal encoding | |
130 | allows characters from almost every known script to be intermixed in a | |
131 | single buffer or string. Emacs translates between the multibyte | |
132 | character encoding and various other coding systems when reading and | |
133 | writing files, and when exchanging data with subprocesses. | |
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134 | |
135 | @kindex C-h h | |
136 | @findex view-hello-file | |
137 | @cindex undisplayable characters | |
138 | @cindex @samp{?} in display | |
139 | The command @kbd{C-h h} (@code{view-hello-file}) displays the file | |
140 | @file{etc/HELLO}, which shows how to say ``hello'' in many languages. | |
141 | This illustrates various scripts. If some characters can't be | |
142 | displayed on your terminal, they appear as @samp{?} or as hollow boxes | |
143 | (@pxref{Undisplayable Characters}). | |
144 | ||
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145 | Keyboards, even in the countries where these character sets are |
146 | used, generally don't have keys for all the characters in them. You | |
147 | can insert characters that your keyboard does not support, using | |
148 | @kbd{C-q} (@code{quoted-insert}) or @kbd{C-x 8 @key{RET}} | |
149 | (@code{ucs-insert}). @xref{Inserting Text}. Emacs also supports | |
150 | various @dfn{input methods}, typically one for each script or | |
151 | language, which make it easier to type characters in the script. | |
152 | @xref{Input Methods}. | |
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153 | |
154 | @kindex C-x RET | |
155 | The prefix key @kbd{C-x @key{RET}} is used for commands that pertain | |
156 | to multibyte characters, coding systems, and input methods. | |
157 | ||
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158 | @kindex C-x = |
159 | @findex what-cursor-position | |
160 | The command @kbd{C-x =} (@code{what-cursor-position}) shows | |
161 | information about the character at point. In addition to the | |
162 | character position, which was described in @ref{Position Info}, this | |
163 | command displays how the character is encoded. For instance, it | |
164 | displays the following line in the echo area for the character | |
165 | @samp{c}: | |
166 | ||
167 | @smallexample | |
168 | Char: c (99, #o143, #x63) point=28062 of 36168 (78%) column=53 | |
169 | @end smallexample | |
170 | ||
171 | The four values after @samp{Char:} describe the character that | |
172 | follows point, first by showing it and then by giving its character | |
173 | code in decimal, octal and hex. For a non-@acronym{ASCII} multibyte | |
174 | character, these are followed by @samp{file} and the character's | |
175 | representation, in hex, in the buffer's coding system, if that coding | |
176 | system encodes the character safely and with a single byte | |
177 | (@pxref{Coding Systems}). If the character's encoding is longer than | |
178 | one byte, Emacs shows @samp{file ...}. | |
179 | ||
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180 | As a special case, if the character lies in the range 128 (0200 |
181 | octal) through 159 (0237 octal), it stands for a ``raw'' byte that | |
182 | does not correspond to any specific displayable character. Such a | |
183 | ``character'' lies within the @code{eight-bit-control} character set, | |
184 | and is displayed as an escaped octal character code. In this case, | |
185 | @kbd{C-x =} shows @samp{part of display ...} instead of @samp{file}. | |
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186 | |
187 | @cindex character set of character at point | |
188 | @cindex font of character at point | |
189 | @cindex text properties at point | |
190 | @cindex face at point | |
191 | With a prefix argument (@kbd{C-u C-x =}), this command displays a | |
192 | detailed description of the character in a window: | |
193 | ||
194 | @itemize @bullet | |
195 | @item | |
196 | The character set name, and the codes that identify the character | |
197 | within that character set; @acronym{ASCII} characters are identified | |
198 | as belonging to the @code{ascii} character set. | |
199 | ||
200 | @item | |
201 | The character's syntax and categories. | |
202 | ||
203 | @item | |
204 | The character's encodings, both internally in the buffer, and externally | |
205 | if you were to save the file. | |
206 | ||
207 | @item | |
208 | What keys to type to input the character in the current input method | |
209 | (if it supports the character). | |
210 | ||
211 | @item | |
212 | If you are running Emacs on a graphical display, the font name and | |
213 | glyph code for the character. If you are running Emacs on a text-only | |
214 | terminal, the code(s) sent to the terminal. | |
215 | ||
216 | @item | |
217 | The character's text properties (@pxref{Text Properties,,, | |
218 | elisp, the Emacs Lisp Reference Manual}), including any non-default | |
219 | faces used to display the character, and any overlays containing it | |
220 | (@pxref{Overlays,,, elisp, the same manual}). | |
221 | @end itemize | |
222 | ||
223 | Here's an example showing the Latin-1 character A with grave accent, | |
224 | in a buffer whose coding system is @code{utf-8-unix}: | |
225 | ||
226 | @smallexample | |
227 | character: @`A (192, #o300, #xc0) | |
228 | preferred charset: unicode (Unicode (ISO10646)) | |
229 | code point: 0xC0 | |
53507b2c | 230 | syntax: w which means: word |
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231 | category: j:Japanese l:Latin v:Vietnamese |
232 | buffer code: #xC3 #x80 | |
233 | file code: not encodable by coding system undecided-unix | |
234 | display: by this font (glyph code) | |
235 | xft:-unknown-DejaVu Sans Mono-normal-normal-normal-*-13-*-*-*-m-0-iso10646-1 (#x82) | |
236 | ||
237 | Character code properties: customize what to show | |
238 | name: LATIN CAPITAL LETTER A WITH GRAVE | |
239 | general-category: Lu (Letter, Uppercase) | |
240 | decomposition: (65 768) ('A' 'Ì€') | |
241 | old-name: LATIN CAPITAL LETTER A GRAVE | |
242 | ||
243 | There are text properties here: | |
244 | auto-composed t | |
245 | @end smallexample | |
246 | ||
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247 | @node Enabling Multibyte |
248 | @section Enabling Multibyte Characters | |
249 | ||
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250 | By default, Emacs starts in multibyte mode: it stores the contents |
251 | of buffers and strings using an internal encoding that represents | |
252 | non-@acronym{ASCII} characters using multi-byte sequences. Multibyte | |
253 | mode allows you to use all the supported languages and scripts without | |
254 | limitations. | |
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255 | |
256 | @cindex turn multibyte support on or off | |
ad36c422 | 257 | Under very special circumstances, you may want to disable multibyte |
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258 | character support, for a specific buffer. |
259 | When multibyte characters are disabled in a buffer, we call | |
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260 | that @dfn{unibyte mode}. In unibyte mode, each character in the |
261 | buffer has a character code ranging from 0 through 255 (0377 octal); 0 | |
262 | through 127 (0177 octal) represent @acronym{ASCII} characters, and 128 | |
263 | (0200 octal) through 255 (0377 octal) represent non-@acronym{ASCII} | |
264 | characters. | |
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265 | |
266 | To edit a particular file in unibyte representation, visit it using | |
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267 | @code{find-file-literally}. @xref{Visiting}. You can convert a |
268 | multibyte buffer to unibyte by saving it to a file, killing the | |
269 | buffer, and visiting the file again with @code{find-file-literally}. | |
270 | Alternatively, you can use @kbd{C-x @key{RET} c} | |
271 | (@code{universal-coding-system-argument}) and specify @samp{raw-text} | |
272 | as the coding system with which to visit or save a file. @xref{Text | |
273 | Coding}. Unlike @code{find-file-literally}, finding a file as | |
274 | @samp{raw-text} doesn't disable format conversion, uncompression, or | |
275 | auto mode selection. | |
8cf51b2c | 276 | |
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277 | @cindex Lisp files, and multibyte operation |
278 | @cindex multibyte operation, and Lisp files | |
279 | @cindex unibyte operation, and Lisp files | |
280 | @cindex init file, and non-@acronym{ASCII} characters | |
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281 | Emacs normally loads Lisp files as multibyte. |
282 | This includes the Emacs initialization | |
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283 | file, @file{.emacs}, and the initialization files of Emacs packages |
284 | such as Gnus. However, you can specify unibyte loading for a | |
285 | particular Lisp file, by putting @w{@samp{-*-unibyte: t;-*-}} in a | |
286 | comment on the first line (@pxref{File Variables}). Then that file is | |
287 | always loaded as unibyte text. The motivation for these conventions | |
288 | is that it is more reliable to always load any particular Lisp file in | |
289 | the same way. However, you can load a Lisp file as unibyte, on any | |
290 | one occasion, by typing @kbd{C-x @key{RET} c raw-text @key{RET}} | |
291 | immediately before loading it. | |
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292 | |
293 | The mode line indicates whether multibyte character support is | |
294 | enabled in the current buffer. If it is, there are two or more | |
295 | characters (most often two dashes) near the beginning of the mode | |
296 | line, before the indication of the visited file's end-of-line | |
297 | convention (colon, backslash, etc.). When multibyte characters | |
298 | are not enabled, nothing precedes the colon except a single dash. | |
299 | @xref{Mode Line}, for more details about this. | |
300 | ||
ad36c422 | 301 | @findex toggle-enable-multibyte-characters |
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302 | You can turn on multibyte support in a specific buffer by invoking the |
303 | command @code{toggle-enable-multibyte-characters} in that buffer. | |
ad36c422 | 304 | |
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305 | @node Language Environments |
306 | @section Language Environments | |
307 | @cindex language environments | |
308 | ||
309 | All supported character sets are supported in Emacs buffers whenever | |
310 | multibyte characters are enabled; there is no need to select a | |
311 | particular language in order to display its characters in an Emacs | |
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312 | buffer. However, it is important to select a @dfn{language |
313 | environment} in order to set various defaults. Roughly speaking, the | |
314 | language environment represents a choice of preferred script rather | |
315 | than a choice of language. | |
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316 | |
317 | The language environment controls which coding systems to recognize | |
318 | when reading text (@pxref{Recognize Coding}). This applies to files, | |
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319 | incoming mail, and any other text you read into Emacs. It may also |
320 | specify the default coding system to use when you create a file. Each | |
321 | language environment also specifies a default input method. | |
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322 | |
323 | @findex set-language-environment | |
324 | @vindex current-language-environment | |
ad36c422 | 325 | To select a language environment, customize the variable |
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326 | @code{current-language-environment} or use the command @kbd{M-x |
327 | set-language-environment}. It makes no difference which buffer is | |
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328 | current when you use this command, because the effects apply globally |
329 | to the Emacs session. The supported language environments include: | |
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330 | |
331 | @cindex Euro sign | |
332 | @cindex UTF-8 | |
333 | @quotation | |
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334 | ASCII, Belarusian, Bengali, Brazilian Portuguese, Bulgarian, |
335 | Chinese-BIG5, Chinese-CNS, Chinese-EUC-TW, Chinese-GB, Chinese-GBK, | |
336 | Chinese-GB18030, Croatian, Cyrillic-ALT, Cyrillic-ISO, Cyrillic-KOI8, | |
337 | Czech, Devanagari, Dutch, English, Esperanto, Ethiopic, French, | |
338 | Georgian, German, Greek, Gujarati, Hebrew, IPA, Italian, Japanese, | |
339 | Kannada, Khmer, Korean, Lao, Latin-1, Latin-2, Latin-3, Latin-4, | |
340 | Latin-5, Latin-6, Latin-7, Latin-8 (Celtic), Latin-9 (updated Latin-1 | |
341 | with the Euro sign), Latvian, Lithuanian, Malayalam, Oriya, Polish, | |
342 | Punjabi, Romanian, Russian, Sinhala, Slovak, Slovenian, Spanish, | |
343 | Swedish, TaiViet, Tajik, Tamil, Telugu, Thai, Tibetan, Turkish, UTF-8 | |
344 | (for a setup which prefers Unicode characters and files encoded in | |
345 | UTF-8), Ukrainian, Vietnamese, Welsh, and Windows-1255 (for a setup | |
346 | which prefers Cyrillic characters and files encoded in Windows-1255). | |
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347 | @end quotation |
348 | ||
349 | @cindex fonts for various scripts | |
350 | @cindex Intlfonts package, installation | |
351 | To display the script(s) used by your language environment on a | |
352 | graphical display, you need to have a suitable font. If some of the | |
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353 | characters appear as empty boxes or hex codes, you should install the |
354 | GNU Intlfonts package, which includes fonts for most supported | |
355 | scripts.@footnote{If you run Emacs on X, you need to inform the X | |
356 | server about the location of the newly installed fonts with the | |
357 | following commands: | |
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358 | |
359 | @example | |
360 | xset fp+ /usr/local/share/emacs/fonts | |
361 | xset fp rehash | |
362 | @end example | |
363 | } | |
364 | @xref{Fontsets}, for more details about setting up your fonts. | |
365 | ||
366 | @findex set-locale-environment | |
367 | @vindex locale-language-names | |
368 | @vindex locale-charset-language-names | |
369 | @cindex locales | |
370 | Some operating systems let you specify the character-set locale you | |
371 | are using by setting the locale environment variables @env{LC_ALL}, | |
372 | @env{LC_CTYPE}, or @env{LANG}.@footnote{If more than one of these is | |
373 | set, the first one that is nonempty specifies your locale for this | |
374 | purpose.} During startup, Emacs looks up your character-set locale's | |
375 | name in the system locale alias table, matches its canonical name | |
376 | against entries in the value of the variables | |
377 | @code{locale-charset-language-names} and @code{locale-language-names}, | |
378 | and selects the corresponding language environment if a match is found. | |
379 | (The former variable overrides the latter.) It also adjusts the display | |
380 | table and terminal coding system, the locale coding system, the | |
381 | preferred coding system as needed for the locale, and---last but not | |
382 | least---the way Emacs decodes non-@acronym{ASCII} characters sent by your keyboard. | |
383 | ||
384 | If you modify the @env{LC_ALL}, @env{LC_CTYPE}, or @env{LANG} | |
385 | environment variables while running Emacs, you may want to invoke the | |
386 | @code{set-locale-environment} function afterwards to readjust the | |
387 | language environment from the new locale. | |
388 | ||
389 | @vindex locale-preferred-coding-systems | |
390 | The @code{set-locale-environment} function normally uses the preferred | |
391 | coding system established by the language environment to decode system | |
392 | messages. But if your locale matches an entry in the variable | |
393 | @code{locale-preferred-coding-systems}, Emacs uses the corresponding | |
394 | coding system instead. For example, if the locale @samp{ja_JP.PCK} | |
395 | matches @code{japanese-shift-jis} in | |
396 | @code{locale-preferred-coding-systems}, Emacs uses that encoding even | |
397 | though it might normally use @code{japanese-iso-8bit}. | |
398 | ||
399 | You can override the language environment chosen at startup with | |
400 | explicit use of the command @code{set-language-environment}, or with | |
401 | customization of @code{current-language-environment} in your init | |
402 | file. | |
403 | ||
404 | @kindex C-h L | |
405 | @findex describe-language-environment | |
406 | To display information about the effects of a certain language | |
407 | environment @var{lang-env}, use the command @kbd{C-h L @var{lang-env} | |
408 | @key{RET}} (@code{describe-language-environment}). This tells you | |
409 | which languages this language environment is useful for, and lists the | |
410 | character sets, coding systems, and input methods that go with it. It | |
411 | also shows some sample text to illustrate scripts used in this | |
412 | language environment. If you give an empty input for @var{lang-env}, | |
413 | this command describes the chosen language environment. | |
d2fac4a9 | 414 | @anchor{Describe Language Environment} |
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415 | |
416 | @vindex set-language-environment-hook | |
417 | You can customize any language environment with the normal hook | |
418 | @code{set-language-environment-hook}. The command | |
419 | @code{set-language-environment} runs that hook after setting up the new | |
420 | language environment. The hook functions can test for a specific | |
421 | language environment by checking the variable | |
422 | @code{current-language-environment}. This hook is where you should | |
423 | put non-default settings for specific language environment, such as | |
424 | coding systems for keyboard input and terminal output, the default | |
425 | input method, etc. | |
426 | ||
427 | @vindex exit-language-environment-hook | |
428 | Before it starts to set up the new language environment, | |
429 | @code{set-language-environment} first runs the hook | |
430 | @code{exit-language-environment-hook}. This hook is useful for undoing | |
431 | customizations that were made with @code{set-language-environment-hook}. | |
432 | For instance, if you set up a special key binding in a specific language | |
433 | environment using @code{set-language-environment-hook}, you should set | |
434 | up @code{exit-language-environment-hook} to restore the normal binding | |
435 | for that key. | |
436 | ||
437 | @node Input Methods | |
438 | @section Input Methods | |
439 | ||
440 | @cindex input methods | |
441 | An @dfn{input method} is a kind of character conversion designed | |
442 | specifically for interactive input. In Emacs, typically each language | |
443 | has its own input method; sometimes several languages which use the same | |
444 | characters can share one input method. A few languages support several | |
445 | input methods. | |
446 | ||
447 | The simplest kind of input method works by mapping @acronym{ASCII} letters | |
448 | into another alphabet; this allows you to use one other alphabet | |
449 | instead of @acronym{ASCII}. The Greek and Russian input methods | |
450 | work this way. | |
451 | ||
452 | A more powerful technique is composition: converting sequences of | |
453 | characters into one letter. Many European input methods use composition | |
454 | to produce a single non-@acronym{ASCII} letter from a sequence that consists of a | |
455 | letter followed by accent characters (or vice versa). For example, some | |
456 | methods convert the sequence @kbd{a'} into a single accented letter. | |
457 | These input methods have no special commands of their own; all they do | |
458 | is compose sequences of printing characters. | |
459 | ||
460 | The input methods for syllabic scripts typically use mapping followed | |
461 | by composition. The input methods for Thai and Korean work this way. | |
462 | First, letters are mapped into symbols for particular sounds or tone | |
463 | marks; then, sequences of these which make up a whole syllable are | |
464 | mapped into one syllable sign. | |
465 | ||
466 | Chinese and Japanese require more complex methods. In Chinese input | |
467 | methods, first you enter the phonetic spelling of a Chinese word (in | |
468 | input method @code{chinese-py}, among others), or a sequence of | |
469 | portions of the character (input methods @code{chinese-4corner} and | |
470 | @code{chinese-sw}, and others). One input sequence typically | |
471 | corresponds to many possible Chinese characters. You select the one | |
472 | you mean using keys such as @kbd{C-f}, @kbd{C-b}, @kbd{C-n}, | |
473 | @kbd{C-p}, and digits, which have special meanings in this situation. | |
474 | ||
475 | The possible characters are conceptually arranged in several rows, | |
476 | with each row holding up to 10 alternatives. Normally, Emacs displays | |
477 | just one row at a time, in the echo area; @code{(@var{i}/@var{j})} | |
478 | appears at the beginning, to indicate that this is the @var{i}th row | |
479 | out of a total of @var{j} rows. Type @kbd{C-n} or @kbd{C-p} to | |
480 | display the next row or the previous row. | |
481 | ||
482 | Type @kbd{C-f} and @kbd{C-b} to move forward and backward among | |
483 | the alternatives in the current row. As you do this, Emacs highlights | |
484 | the current alternative with a special color; type @code{C-@key{SPC}} | |
485 | to select the current alternative and use it as input. The | |
486 | alternatives in the row are also numbered; the number appears before | |
487 | the alternative. Typing a digit @var{n} selects the @var{n}th | |
488 | alternative of the current row and uses it as input. | |
489 | ||
490 | @key{TAB} in these Chinese input methods displays a buffer showing | |
491 | all the possible characters at once; then clicking @kbd{Mouse-2} on | |
492 | one of them selects that alternative. The keys @kbd{C-f}, @kbd{C-b}, | |
493 | @kbd{C-n}, @kbd{C-p}, and digits continue to work as usual, but they | |
494 | do the highlighting in the buffer showing the possible characters, | |
495 | rather than in the echo area. | |
496 | ||
497 | In Japanese input methods, first you input a whole word using | |
498 | phonetic spelling; then, after the word is in the buffer, Emacs | |
499 | converts it into one or more characters using a large dictionary. One | |
500 | phonetic spelling corresponds to a number of different Japanese words; | |
501 | to select one of them, use @kbd{C-n} and @kbd{C-p} to cycle through | |
502 | the alternatives. | |
503 | ||
504 | Sometimes it is useful to cut off input method processing so that the | |
505 | characters you have just entered will not combine with subsequent | |
506 | characters. For example, in input method @code{latin-1-postfix}, the | |
507 | sequence @kbd{e '} combines to form an @samp{e} with an accent. What if | |
508 | you want to enter them as separate characters? | |
509 | ||
510 | One way is to type the accent twice; this is a special feature for | |
511 | entering the separate letter and accent. For example, @kbd{e ' '} gives | |
512 | you the two characters @samp{e'}. Another way is to type another letter | |
513 | after the @kbd{e}---something that won't combine with that---and | |
514 | immediately delete it. For example, you could type @kbd{e e @key{DEL} | |
515 | '} to get separate @samp{e} and @samp{'}. | |
516 | ||
517 | Another method, more general but not quite as easy to type, is to use | |
518 | @kbd{C-\ C-\} between two characters to stop them from combining. This | |
519 | is the command @kbd{C-\} (@code{toggle-input-method}) used twice. | |
520 | @ifnottex | |
521 | @xref{Select Input Method}. | |
522 | @end ifnottex | |
523 | ||
524 | @cindex incremental search, input method interference | |
525 | @kbd{C-\ C-\} is especially useful inside an incremental search, | |
526 | because it stops waiting for more characters to combine, and starts | |
527 | searching for what you have already entered. | |
528 | ||
529 | To find out how to input the character after point using the current | |
530 | input method, type @kbd{C-u C-x =}. @xref{Position Info}. | |
531 | ||
532 | @vindex input-method-verbose-flag | |
533 | @vindex input-method-highlight-flag | |
534 | The variables @code{input-method-highlight-flag} and | |
535 | @code{input-method-verbose-flag} control how input methods explain | |
536 | what is happening. If @code{input-method-highlight-flag} is | |
537 | non-@code{nil}, the partial sequence is highlighted in the buffer (for | |
538 | most input methods---some disable this feature). If | |
539 | @code{input-method-verbose-flag} is non-@code{nil}, the list of | |
540 | possible characters to type next is displayed in the echo area (but | |
541 | not when you are in the minibuffer). | |
542 | ||
ce79424f EZ |
543 | Another facility for typing characters not on your keyboard is by |
544 | using the @kbd{C-x 8 @key{RET}} (@code{ucs-insert}) to insert a single | |
545 | character based on its Unicode name or code-point; see @ref{Inserting | |
546 | Text}. | |
547 | ||
8cf51b2c GM |
548 | @node Select Input Method |
549 | @section Selecting an Input Method | |
550 | ||
551 | @table @kbd | |
552 | @item C-\ | |
553 | Enable or disable use of the selected input method. | |
554 | ||
555 | @item C-x @key{RET} C-\ @var{method} @key{RET} | |
556 | Select a new input method for the current buffer. | |
557 | ||
558 | @item C-h I @var{method} @key{RET} | |
559 | @itemx C-h C-\ @var{method} @key{RET} | |
560 | @findex describe-input-method | |
561 | @kindex C-h I | |
562 | @kindex C-h C-\ | |
563 | Describe the input method @var{method} (@code{describe-input-method}). | |
564 | By default, it describes the current input method (if any). This | |
565 | description should give you the full details of how to use any | |
566 | particular input method. | |
567 | ||
568 | @item M-x list-input-methods | |
569 | Display a list of all the supported input methods. | |
570 | @end table | |
571 | ||
572 | @findex set-input-method | |
573 | @vindex current-input-method | |
574 | @kindex C-x RET C-\ | |
575 | To choose an input method for the current buffer, use @kbd{C-x | |
576 | @key{RET} C-\} (@code{set-input-method}). This command reads the | |
577 | input method name from the minibuffer; the name normally starts with the | |
578 | language environment that it is meant to be used with. The variable | |
579 | @code{current-input-method} records which input method is selected. | |
580 | ||
581 | @findex toggle-input-method | |
582 | @kindex C-\ | |
583 | Input methods use various sequences of @acronym{ASCII} characters to | |
584 | stand for non-@acronym{ASCII} characters. Sometimes it is useful to | |
585 | turn off the input method temporarily. To do this, type @kbd{C-\} | |
586 | (@code{toggle-input-method}). To reenable the input method, type | |
587 | @kbd{C-\} again. | |
588 | ||
589 | If you type @kbd{C-\} and you have not yet selected an input method, | |
590 | it prompts for you to specify one. This has the same effect as using | |
591 | @kbd{C-x @key{RET} C-\} to specify an input method. | |
592 | ||
593 | When invoked with a numeric argument, as in @kbd{C-u C-\}, | |
594 | @code{toggle-input-method} always prompts you for an input method, | |
595 | suggesting the most recently selected one as the default. | |
596 | ||
597 | @vindex default-input-method | |
598 | Selecting a language environment specifies a default input method for | |
599 | use in various buffers. When you have a default input method, you can | |
600 | select it in the current buffer by typing @kbd{C-\}. The variable | |
601 | @code{default-input-method} specifies the default input method | |
602 | (@code{nil} means there is none). | |
603 | ||
604 | In some language environments, which support several different input | |
605 | methods, you might want to use an input method different from the | |
606 | default chosen by @code{set-language-environment}. You can instruct | |
607 | Emacs to select a different default input method for a certain | |
608 | language environment, if you wish, by using | |
609 | @code{set-language-environment-hook} (@pxref{Language Environments, | |
610 | set-language-environment-hook}). For example: | |
611 | ||
612 | @lisp | |
613 | (defun my-chinese-setup () | |
614 | "Set up my private Chinese environment." | |
615 | (if (equal current-language-environment "Chinese-GB") | |
616 | (setq default-input-method "chinese-tonepy"))) | |
617 | (add-hook 'set-language-environment-hook 'my-chinese-setup) | |
618 | @end lisp | |
619 | ||
620 | @noindent | |
621 | This sets the default input method to be @code{chinese-tonepy} | |
622 | whenever you choose a Chinese-GB language environment. | |
623 | ||
0cf8a906 KH |
624 | You can instruct Emacs to activate a certain input method |
625 | automatically. For example: | |
626 | ||
627 | @lisp | |
628 | (add-hook 'text-mode-hook | |
629 | (lambda () (set-input-method "german-prefix"))) | |
630 | @end lisp | |
631 | ||
632 | @noindent | |
d3b396e4 | 633 | This activates the input method ``german-prefix'' automatically in the |
0cf8a906 KH |
634 | Text mode. |
635 | ||
8cf51b2c GM |
636 | @findex quail-set-keyboard-layout |
637 | Some input methods for alphabetic scripts work by (in effect) | |
638 | remapping the keyboard to emulate various keyboard layouts commonly used | |
639 | for those scripts. How to do this remapping properly depends on your | |
640 | actual keyboard layout. To specify which layout your keyboard has, use | |
641 | the command @kbd{M-x quail-set-keyboard-layout}. | |
642 | ||
643 | @findex quail-show-key | |
644 | You can use the command @kbd{M-x quail-show-key} to show what key (or | |
645 | key sequence) to type in order to input the character following point, | |
646 | using the selected keyboard layout. The command @kbd{C-u C-x =} also | |
647 | shows that information in addition to the other information about the | |
648 | character. | |
649 | ||
650 | @findex list-input-methods | |
651 | To see a list of all the supported input methods, type @kbd{M-x | |
652 | list-input-methods}. The list gives information about each input | |
653 | method, including the string that stands for it in the mode line. | |
654 | ||
8cf51b2c GM |
655 | @node Coding Systems |
656 | @section Coding Systems | |
657 | @cindex coding systems | |
658 | ||
659 | Users of various languages have established many more-or-less standard | |
660 | coding systems for representing them. Emacs does not use these coding | |
661 | systems internally; instead, it converts from various coding systems to | |
662 | its own system when reading data, and converts the internal coding | |
663 | system to other coding systems when writing data. Conversion is | |
664 | possible in reading or writing files, in sending or receiving from the | |
665 | terminal, and in exchanging data with subprocesses. | |
666 | ||
667 | Emacs assigns a name to each coding system. Most coding systems are | |
ad36c422 CY |
668 | used for one language, and the name of the coding system starts with |
669 | the language name. Some coding systems are used for several | |
670 | languages; their names usually start with @samp{iso}. There are also | |
671 | special coding systems, such as @code{no-conversion}, @code{raw-text}, | |
672 | and @code{emacs-internal}. | |
8cf51b2c GM |
673 | |
674 | @cindex international files from DOS/Windows systems | |
675 | A special class of coding systems, collectively known as | |
676 | @dfn{codepages}, is designed to support text encoded by MS-Windows and | |
677 | MS-DOS software. The names of these coding systems are | |
678 | @code{cp@var{nnnn}}, where @var{nnnn} is a 3- or 4-digit number of the | |
679 | codepage. You can use these encodings just like any other coding | |
680 | system; for example, to visit a file encoded in codepage 850, type | |
681 | @kbd{C-x @key{RET} c cp850 @key{RET} C-x C-f @var{filename} | |
f68eb991 | 682 | @key{RET}}. |
8cf51b2c GM |
683 | |
684 | In addition to converting various representations of non-@acronym{ASCII} | |
685 | characters, a coding system can perform end-of-line conversion. Emacs | |
686 | handles three different conventions for how to separate lines in a file: | |
687 | newline, carriage-return linefeed, and just carriage-return. | |
688 | ||
689 | @table @kbd | |
690 | @item C-h C @var{coding} @key{RET} | |
691 | Describe coding system @var{coding}. | |
692 | ||
693 | @item C-h C @key{RET} | |
694 | Describe the coding systems currently in use. | |
695 | ||
696 | @item M-x list-coding-systems | |
697 | Display a list of all the supported coding systems. | |
698 | @end table | |
699 | ||
700 | @kindex C-h C | |
701 | @findex describe-coding-system | |
702 | The command @kbd{C-h C} (@code{describe-coding-system}) displays | |
703 | information about particular coding systems, including the end-of-line | |
704 | conversion specified by those coding systems. You can specify a coding | |
705 | system name as the argument; alternatively, with an empty argument, it | |
706 | describes the coding systems currently selected for various purposes, | |
707 | both in the current buffer and as the defaults, and the priority list | |
708 | for recognizing coding systems (@pxref{Recognize Coding}). | |
709 | ||
710 | @findex list-coding-systems | |
711 | To display a list of all the supported coding systems, type @kbd{M-x | |
712 | list-coding-systems}. The list gives information about each coding | |
713 | system, including the letter that stands for it in the mode line | |
714 | (@pxref{Mode Line}). | |
715 | ||
716 | @cindex end-of-line conversion | |
717 | @cindex line endings | |
718 | @cindex MS-DOS end-of-line conversion | |
719 | @cindex Macintosh end-of-line conversion | |
720 | Each of the coding systems that appear in this list---except for | |
721 | @code{no-conversion}, which means no conversion of any kind---specifies | |
722 | how and whether to convert printing characters, but leaves the choice of | |
723 | end-of-line conversion to be decided based on the contents of each file. | |
724 | For example, if the file appears to use the sequence carriage-return | |
725 | linefeed to separate lines, DOS end-of-line conversion will be used. | |
726 | ||
727 | Each of the listed coding systems has three variants which specify | |
728 | exactly what to do for end-of-line conversion: | |
729 | ||
730 | @table @code | |
731 | @item @dots{}-unix | |
732 | Don't do any end-of-line conversion; assume the file uses | |
733 | newline to separate lines. (This is the convention normally used | |
734 | on Unix and GNU systems.) | |
735 | ||
736 | @item @dots{}-dos | |
737 | Assume the file uses carriage-return linefeed to separate lines, and do | |
738 | the appropriate conversion. (This is the convention normally used on | |
739 | Microsoft systems.@footnote{It is also specified for MIME @samp{text/*} | |
740 | bodies and in other network transport contexts. It is different | |
741 | from the SGML reference syntax record-start/record-end format which | |
742 | Emacs doesn't support directly.}) | |
743 | ||
744 | @item @dots{}-mac | |
745 | Assume the file uses carriage-return to separate lines, and do the | |
746 | appropriate conversion. (This is the convention normally used on the | |
747 | Macintosh system.) | |
748 | @end table | |
749 | ||
750 | These variant coding systems are omitted from the | |
751 | @code{list-coding-systems} display for brevity, since they are entirely | |
752 | predictable. For example, the coding system @code{iso-latin-1} has | |
753 | variants @code{iso-latin-1-unix}, @code{iso-latin-1-dos} and | |
754 | @code{iso-latin-1-mac}. | |
755 | ||
756 | @cindex @code{undecided}, coding system | |
757 | The coding systems @code{unix}, @code{dos}, and @code{mac} are | |
758 | aliases for @code{undecided-unix}, @code{undecided-dos}, and | |
759 | @code{undecided-mac}, respectively. These coding systems specify only | |
760 | the end-of-line conversion, and leave the character code conversion to | |
761 | be deduced from the text itself. | |
762 | ||
763 | The coding system @code{raw-text} is good for a file which is mainly | |
764 | @acronym{ASCII} text, but may contain byte values above 127 which are | |
765 | not meant to encode non-@acronym{ASCII} characters. With | |
766 | @code{raw-text}, Emacs copies those byte values unchanged, and sets | |
767 | @code{enable-multibyte-characters} to @code{nil} in the current buffer | |
768 | so that they will be interpreted properly. @code{raw-text} handles | |
769 | end-of-line conversion in the usual way, based on the data | |
770 | encountered, and has the usual three variants to specify the kind of | |
771 | end-of-line conversion to use. | |
772 | ||
773 | In contrast, the coding system @code{no-conversion} specifies no | |
774 | character code conversion at all---none for non-@acronym{ASCII} byte values and | |
775 | none for end of line. This is useful for reading or writing binary | |
776 | files, tar files, and other files that must be examined verbatim. It, | |
777 | too, sets @code{enable-multibyte-characters} to @code{nil}. | |
778 | ||
779 | The easiest way to edit a file with no conversion of any kind is with | |
780 | the @kbd{M-x find-file-literally} command. This uses | |
781 | @code{no-conversion}, and also suppresses other Emacs features that | |
782 | might convert the file contents before you see them. @xref{Visiting}. | |
783 | ||
ad36c422 CY |
784 | The coding system @code{emacs-internal} (or @code{utf-8-emacs}, |
785 | which is equivalent) means that the file contains non-@acronym{ASCII} | |
786 | characters stored with the internal Emacs encoding. This coding | |
787 | system handles end-of-line conversion based on the data encountered, | |
788 | and has the usual three variants to specify the kind of end-of-line | |
789 | conversion. | |
8cf51b2c GM |
790 | |
791 | @node Recognize Coding | |
792 | @section Recognizing Coding Systems | |
793 | ||
ad36c422 CY |
794 | Whenever Emacs reads a given piece of text, it tries to recognize |
795 | which coding system to use. This applies to files being read, output | |
796 | from subprocesses, text from X selections, etc. Emacs can select the | |
797 | right coding system automatically most of the time---once you have | |
798 | specified your preferences. | |
8cf51b2c GM |
799 | |
800 | Some coding systems can be recognized or distinguished by which byte | |
801 | sequences appear in the data. However, there are coding systems that | |
802 | cannot be distinguished, not even potentially. For example, there is no | |
803 | way to distinguish between Latin-1 and Latin-2; they use the same byte | |
804 | values with different meanings. | |
805 | ||
806 | Emacs handles this situation by means of a priority list of coding | |
807 | systems. Whenever Emacs reads a file, if you do not specify the coding | |
808 | system to use, Emacs checks the data against each coding system, | |
809 | starting with the first in priority and working down the list, until it | |
810 | finds a coding system that fits the data. Then it converts the file | |
811 | contents assuming that they are represented in this coding system. | |
812 | ||
813 | The priority list of coding systems depends on the selected language | |
814 | environment (@pxref{Language Environments}). For example, if you use | |
815 | French, you probably want Emacs to prefer Latin-1 to Latin-2; if you use | |
816 | Czech, you probably want Latin-2 to be preferred. This is one of the | |
817 | reasons to specify a language environment. | |
818 | ||
819 | @findex prefer-coding-system | |
820 | However, you can alter the coding system priority list in detail | |
821 | with the command @kbd{M-x prefer-coding-system}. This command reads | |
822 | the name of a coding system from the minibuffer, and adds it to the | |
823 | front of the priority list, so that it is preferred to all others. If | |
824 | you use this command several times, each use adds one element to the | |
825 | front of the priority list. | |
826 | ||
827 | If you use a coding system that specifies the end-of-line conversion | |
828 | type, such as @code{iso-8859-1-dos}, what this means is that Emacs | |
829 | should attempt to recognize @code{iso-8859-1} with priority, and should | |
830 | use DOS end-of-line conversion when it does recognize @code{iso-8859-1}. | |
831 | ||
832 | @vindex file-coding-system-alist | |
833 | Sometimes a file name indicates which coding system to use for the | |
834 | file. The variable @code{file-coding-system-alist} specifies this | |
835 | correspondence. There is a special function | |
836 | @code{modify-coding-system-alist} for adding elements to this list. For | |
837 | example, to read and write all @samp{.txt} files using the coding system | |
838 | @code{chinese-iso-8bit}, you can execute this Lisp expression: | |
839 | ||
840 | @smallexample | |
841 | (modify-coding-system-alist 'file "\\.txt\\'" 'chinese-iso-8bit) | |
842 | @end smallexample | |
843 | ||
844 | @noindent | |
845 | The first argument should be @code{file}, the second argument should be | |
846 | a regular expression that determines which files this applies to, and | |
847 | the third argument says which coding system to use for these files. | |
848 | ||
849 | @vindex inhibit-eol-conversion | |
850 | @cindex DOS-style end-of-line display | |
851 | Emacs recognizes which kind of end-of-line conversion to use based on | |
852 | the contents of the file: if it sees only carriage-returns, or only | |
853 | carriage-return linefeed sequences, then it chooses the end-of-line | |
854 | conversion accordingly. You can inhibit the automatic use of | |
855 | end-of-line conversion by setting the variable @code{inhibit-eol-conversion} | |
856 | to non-@code{nil}. If you do that, DOS-style files will be displayed | |
857 | with the @samp{^M} characters visible in the buffer; some people | |
858 | prefer this to the more subtle @samp{(DOS)} end-of-line type | |
859 | indication near the left edge of the mode line (@pxref{Mode Line, | |
860 | eol-mnemonic}). | |
861 | ||
862 | @vindex inhibit-iso-escape-detection | |
863 | @cindex escape sequences in files | |
864 | By default, the automatic detection of coding system is sensitive to | |
865 | escape sequences. If Emacs sees a sequence of characters that begin | |
866 | with an escape character, and the sequence is valid as an ISO-2022 | |
867 | code, that tells Emacs to use one of the ISO-2022 encodings to decode | |
868 | the file. | |
869 | ||
870 | However, there may be cases that you want to read escape sequences | |
871 | in a file as is. In such a case, you can set the variable | |
872 | @code{inhibit-iso-escape-detection} to non-@code{nil}. Then the code | |
873 | detection ignores any escape sequences, and never uses an ISO-2022 | |
874 | encoding. The result is that all escape sequences become visible in | |
875 | the buffer. | |
876 | ||
877 | The default value of @code{inhibit-iso-escape-detection} is | |
878 | @code{nil}. We recommend that you not change it permanently, only for | |
879 | one specific operation. That's because many Emacs Lisp source files | |
880 | in the Emacs distribution contain non-@acronym{ASCII} characters encoded in the | |
881 | coding system @code{iso-2022-7bit}, and they won't be | |
882 | decoded correctly when you visit those files if you suppress the | |
883 | escape sequence detection. | |
884 | ||
885 | @vindex auto-coding-alist | |
886 | @vindex auto-coding-regexp-alist | |
887 | @vindex auto-coding-functions | |
888 | The variables @code{auto-coding-alist}, | |
889 | @code{auto-coding-regexp-alist} and @code{auto-coding-functions} are | |
890 | the strongest way to specify the coding system for certain patterns of | |
891 | file names, or for files containing certain patterns; these variables | |
892 | even override @samp{-*-coding:-*-} tags in the file itself. Emacs | |
893 | uses @code{auto-coding-alist} for tar and archive files, to prevent it | |
894 | from being confused by a @samp{-*-coding:-*-} tag in a member of the | |
895 | archive and thinking it applies to the archive file as a whole. | |
896 | Likewise, Emacs uses @code{auto-coding-regexp-alist} to ensure that | |
897 | RMAIL files, whose names in general don't match any particular | |
898 | pattern, are decoded correctly. One of the builtin | |
899 | @code{auto-coding-functions} detects the encoding for XML files. | |
900 | ||
901 | @vindex rmail-decode-mime-charset | |
ad36c422 | 902 | @vindex rmail-file-coding-system |
8cf51b2c GM |
903 | When you get new mail in Rmail, each message is translated |
904 | automatically from the coding system it is written in, as if it were a | |
905 | separate file. This uses the priority list of coding systems that you | |
906 | have specified. If a MIME message specifies a character set, Rmail | |
907 | obeys that specification, unless @code{rmail-decode-mime-charset} is | |
ad36c422 CY |
908 | @code{nil}. For reading and saving Rmail files themselves, Emacs uses |
909 | the coding system specified by the variable | |
910 | @code{rmail-file-coding-system}. The default value is @code{nil}, | |
911 | which means that Rmail files are not translated (they are read and | |
912 | written in the Emacs internal character code). | |
8cf51b2c GM |
913 | |
914 | @node Specify Coding | |
915 | @section Specifying a File's Coding System | |
916 | ||
917 | If Emacs recognizes the encoding of a file incorrectly, you can | |
918 | reread the file using the correct coding system by typing @kbd{C-x | |
919 | @key{RET} r @var{coding-system} @key{RET}}. To see what coding system | |
920 | Emacs actually used to decode the file, look at the coding system | |
921 | mnemonic letter near the left edge of the mode line (@pxref{Mode | |
922 | Line}), or type @kbd{C-h C @key{RET}}. | |
923 | ||
924 | @vindex coding | |
925 | You can specify the coding system for a particular file in the file | |
926 | itself, using the @w{@samp{-*-@dots{}-*-}} construct at the beginning, | |
927 | or a local variables list at the end (@pxref{File Variables}). You do | |
928 | this by defining a value for the ``variable'' named @code{coding}. | |
929 | Emacs does not really have a variable @code{coding}; instead of | |
930 | setting a variable, this uses the specified coding system for the | |
931 | file. For example, @samp{-*-mode: C; coding: latin-1;-*-} specifies | |
932 | use of the Latin-1 coding system, as well as C mode. When you specify | |
933 | the coding explicitly in the file, that overrides | |
934 | @code{file-coding-system-alist}. | |
935 | ||
8cf51b2c GM |
936 | @node Output Coding |
937 | @section Choosing Coding Systems for Output | |
938 | ||
939 | @vindex buffer-file-coding-system | |
940 | Once Emacs has chosen a coding system for a buffer, it stores that | |
941 | coding system in @code{buffer-file-coding-system}. That makes it the | |
942 | default for operations that write from this buffer into a file, such | |
943 | as @code{save-buffer} and @code{write-region}. You can specify a | |
944 | different coding system for further file output from the buffer using | |
945 | @code{set-buffer-file-coding-system} (@pxref{Text Coding}). | |
946 | ||
947 | You can insert any character Emacs supports into any Emacs buffer, | |
948 | but most coding systems can only handle a subset of these characters. | |
ad36c422 CY |
949 | Therefore, it's possible that the characters you insert cannot be |
950 | encoded with the coding system that will be used to save the buffer. | |
951 | For example, you could visit a text file in Polish, encoded in | |
952 | @code{iso-8859-2}, and add some Russian words to it. When you save | |
8cf51b2c GM |
953 | that buffer, Emacs cannot use the current value of |
954 | @code{buffer-file-coding-system}, because the characters you added | |
955 | cannot be encoded by that coding system. | |
956 | ||
957 | When that happens, Emacs tries the most-preferred coding system (set | |
958 | by @kbd{M-x prefer-coding-system} or @kbd{M-x | |
ad36c422 CY |
959 | set-language-environment}). If that coding system can safely encode |
960 | all of the characters in the buffer, Emacs uses it, and stores its | |
961 | value in @code{buffer-file-coding-system}. Otherwise, Emacs displays | |
962 | a list of coding systems suitable for encoding the buffer's contents, | |
963 | and asks you to choose one of those coding systems. | |
8cf51b2c GM |
964 | |
965 | If you insert the unsuitable characters in a mail message, Emacs | |
966 | behaves a bit differently. It additionally checks whether the | |
967 | most-preferred coding system is recommended for use in MIME messages; | |
968 | if not, Emacs tells you that the most-preferred coding system is not | |
969 | recommended and prompts you for another coding system. This is so you | |
970 | won't inadvertently send a message encoded in a way that your | |
971 | recipient's mail software will have difficulty decoding. (You can | |
972 | still use an unsuitable coding system if you type its name in response | |
973 | to the question.) | |
974 | ||
975 | @vindex sendmail-coding-system | |
e73c2434 CY |
976 | When you send a message with Message mode (@pxref{Sending Mail}), |
977 | Emacs has four different ways to determine the coding system to use | |
978 | for encoding the message text. It tries the buffer's own value of | |
979 | @code{buffer-file-coding-system}, if that is non-@code{nil}. | |
980 | Otherwise, it uses the value of @code{sendmail-coding-system}, if that | |
981 | is non-@code{nil}. The third way is to use the default coding system | |
982 | for new files, which is controlled by your choice of language | |
983 | environment, if that is non-@code{nil}. If all of these three values | |
984 | are @code{nil}, Emacs encodes outgoing mail using the Latin-1 coding | |
985 | system. | |
8cf51b2c GM |
986 | |
987 | @node Text Coding | |
988 | @section Specifying a Coding System for File Text | |
989 | ||
990 | In cases where Emacs does not automatically choose the right coding | |
991 | system for a file's contents, you can use these commands to specify | |
992 | one: | |
993 | ||
994 | @table @kbd | |
995 | @item C-x @key{RET} f @var{coding} @key{RET} | |
996 | Use coding system @var{coding} for saving or revisiting the visited | |
997 | file in the current buffer. | |
998 | ||
999 | @item C-x @key{RET} c @var{coding} @key{RET} | |
1000 | Specify coding system @var{coding} for the immediately following | |
1001 | command. | |
1002 | ||
1003 | @item C-x @key{RET} r @var{coding} @key{RET} | |
1004 | Revisit the current file using the coding system @var{coding}. | |
1005 | ||
1006 | @item M-x recode-region @key{RET} @var{right} @key{RET} @var{wrong} @key{RET} | |
1007 | Convert a region that was decoded using coding system @var{wrong}, | |
1008 | decoding it using coding system @var{right} instead. | |
1009 | @end table | |
1010 | ||
1011 | @kindex C-x RET f | |
1012 | @findex set-buffer-file-coding-system | |
1013 | The command @kbd{C-x @key{RET} f} | |
1014 | (@code{set-buffer-file-coding-system}) sets the file coding system for | |
1015 | the current buffer---in other words, it says which coding system to | |
1016 | use when saving or reverting the visited file. You specify which | |
1017 | coding system using the minibuffer. If you specify a coding system | |
1018 | that cannot handle all of the characters in the buffer, Emacs warns | |
1019 | you about the troublesome characters when you actually save the | |
1020 | buffer. | |
1021 | ||
1022 | @cindex specify end-of-line conversion | |
1023 | You can also use this command to specify the end-of-line conversion | |
1024 | (@pxref{Coding Systems, end-of-line conversion}) for encoding the | |
1025 | current buffer. For example, @kbd{C-x @key{RET} f dos @key{RET}} will | |
1026 | cause Emacs to save the current buffer's text with DOS-style CRLF line | |
1027 | endings. | |
1028 | ||
1029 | @kindex C-x RET c | |
1030 | @findex universal-coding-system-argument | |
1031 | Another way to specify the coding system for a file is when you visit | |
1032 | the file. First use the command @kbd{C-x @key{RET} c} | |
1033 | (@code{universal-coding-system-argument}); this command uses the | |
1034 | minibuffer to read a coding system name. After you exit the minibuffer, | |
1035 | the specified coding system is used for @emph{the immediately following | |
1036 | command}. | |
1037 | ||
1038 | So if the immediately following command is @kbd{C-x C-f}, for example, | |
1039 | it reads the file using that coding system (and records the coding | |
1040 | system for when you later save the file). Or if the immediately following | |
1041 | command is @kbd{C-x C-w}, it writes the file using that coding system. | |
1042 | When you specify the coding system for saving in this way, instead | |
1043 | of with @kbd{C-x @key{RET} f}, there is no warning if the buffer | |
1044 | contains characters that the coding system cannot handle. | |
1045 | ||
1046 | Other file commands affected by a specified coding system include | |
1047 | @kbd{C-x i} and @kbd{C-x C-v}, as well as the other-window variants | |
1048 | of @kbd{C-x C-f}. @kbd{C-x @key{RET} c} also affects commands that | |
1049 | start subprocesses, including @kbd{M-x shell} (@pxref{Shell}). If the | |
1050 | immediately following command does not use the coding system, then | |
1051 | @kbd{C-x @key{RET} c} ultimately has no effect. | |
1052 | ||
1053 | An easy way to visit a file with no conversion is with the @kbd{M-x | |
1054 | find-file-literally} command. @xref{Visiting}. | |
1055 | ||
4e3b4528 SM |
1056 | The default value of the variable @code{buffer-file-coding-system} |
1057 | specifies the choice of coding system to use when you create a new file. | |
1058 | It applies when you find a new file, and when you create a buffer and | |
1059 | then save it in a file. Selecting a language environment typically sets | |
1060 | this variable to a good choice of default coding system for that language | |
8cf51b2c GM |
1061 | environment. |
1062 | ||
1063 | @kindex C-x RET r | |
1064 | @findex revert-buffer-with-coding-system | |
1065 | If you visit a file with a wrong coding system, you can correct this | |
1066 | with @kbd{C-x @key{RET} r} (@code{revert-buffer-with-coding-system}). | |
1067 | This visits the current file again, using a coding system you specify. | |
1068 | ||
1069 | @findex recode-region | |
1070 | If a piece of text has already been inserted into a buffer using the | |
1071 | wrong coding system, you can redo the decoding of it using @kbd{M-x | |
1072 | recode-region}. This prompts you for the proper coding system, then | |
1073 | for the wrong coding system that was actually used, and does the | |
1074 | conversion. It first encodes the region using the wrong coding system, | |
1075 | then decodes it again using the proper coding system. | |
1076 | ||
1077 | @node Communication Coding | |
1078 | @section Coding Systems for Interprocess Communication | |
1079 | ||
1080 | This section explains how to specify coding systems for use | |
1081 | in communication with other processes. | |
1082 | ||
1083 | @table @kbd | |
1084 | @item C-x @key{RET} x @var{coding} @key{RET} | |
1085 | Use coding system @var{coding} for transferring selections to and from | |
1086 | other window-based applications. | |
1087 | ||
1088 | @item C-x @key{RET} X @var{coding} @key{RET} | |
1089 | Use coding system @var{coding} for transferring @emph{one} | |
1090 | selection---the next one---to or from another window-based application. | |
1091 | ||
1092 | @item C-x @key{RET} p @var{input-coding} @key{RET} @var{output-coding} @key{RET} | |
1093 | Use coding systems @var{input-coding} and @var{output-coding} for | |
1094 | subprocess input and output in the current buffer. | |
1095 | ||
1096 | @item C-x @key{RET} c @var{coding} @key{RET} | |
1097 | Specify coding system @var{coding} for the immediately following | |
1098 | command. | |
1099 | @end table | |
1100 | ||
1101 | @kindex C-x RET x | |
1102 | @kindex C-x RET X | |
1103 | @findex set-selection-coding-system | |
1104 | @findex set-next-selection-coding-system | |
1105 | The command @kbd{C-x @key{RET} x} (@code{set-selection-coding-system}) | |
1106 | specifies the coding system for sending selected text to other windowing | |
1107 | applications, and for receiving the text of selections made in other | |
1108 | applications. This command applies to all subsequent selections, until | |
1109 | you override it by using the command again. The command @kbd{C-x | |
1110 | @key{RET} X} (@code{set-next-selection-coding-system}) specifies the | |
1111 | coding system for the next selection made in Emacs or read by Emacs. | |
1112 | ||
53b7759e | 1113 | @vindex x-select-request-type |
221bb7f6 EZ |
1114 | The variable @code{x-select-request-type} specifies the data type to |
1115 | request from the X Window System for receiving text selections from | |
1116 | other applications. If the value is @code{nil} (the default), Emacs | |
1117 | tries @code{COMPOUND_TEXT} and @code{UTF8_STRING}, in this order, and | |
1118 | uses various heuristics to choose the more appropriate of the two | |
1119 | results; if none of these succeed, Emacs falls back on @code{STRING}. | |
1120 | If the value of @code{x-select-request-type} is one of the symbols | |
1121 | @code{COMPOUND_TEXT}, @code{UTF8_STRING}, @code{STRING}, or | |
1122 | @code{TEXT}, Emacs uses only that request type. If the value is a | |
1123 | list of some of these symbols, Emacs tries only the request types in | |
1124 | the list, in order, until one of them succeeds, or until the list is | |
1125 | exhausted. | |
53b7759e | 1126 | |
8cf51b2c GM |
1127 | @kindex C-x RET p |
1128 | @findex set-buffer-process-coding-system | |
1129 | The command @kbd{C-x @key{RET} p} (@code{set-buffer-process-coding-system}) | |
1130 | specifies the coding system for input and output to a subprocess. This | |
1131 | command applies to the current buffer; normally, each subprocess has its | |
1132 | own buffer, and thus you can use this command to specify translation to | |
1133 | and from a particular subprocess by giving the command in the | |
1134 | corresponding buffer. | |
1135 | ||
1136 | You can also use @kbd{C-x @key{RET} c} just before the command that | |
1137 | runs or starts a subprocess, to specify the coding system to use for | |
1138 | communication with that subprocess. | |
1139 | ||
1140 | The default for translation of process input and output depends on the | |
1141 | current language environment. | |
1142 | ||
1143 | @vindex locale-coding-system | |
1144 | @cindex decoding non-@acronym{ASCII} keyboard input on X | |
1145 | The variable @code{locale-coding-system} specifies a coding system | |
1146 | to use when encoding and decoding system strings such as system error | |
1147 | messages and @code{format-time-string} formats and time stamps. That | |
1148 | coding system is also used for decoding non-@acronym{ASCII} keyboard input on X | |
1149 | Window systems. You should choose a coding system that is compatible | |
1150 | with the underlying system's text representation, which is normally | |
1151 | specified by one of the environment variables @env{LC_ALL}, | |
1152 | @env{LC_CTYPE}, and @env{LANG}. (The first one, in the order | |
1153 | specified above, whose value is nonempty is the one that determines | |
1154 | the text representation.) | |
1155 | ||
1156 | @node File Name Coding | |
1157 | @section Coding Systems for File Names | |
1158 | ||
1159 | @table @kbd | |
1160 | @item C-x @key{RET} F @var{coding} @key{RET} | |
1161 | Use coding system @var{coding} for encoding and decoding file | |
1162 | @emph{names}. | |
1163 | @end table | |
1164 | ||
1165 | @vindex file-name-coding-system | |
1166 | @cindex file names with non-@acronym{ASCII} characters | |
1167 | The variable @code{file-name-coding-system} specifies a coding | |
1168 | system to use for encoding file names. It has no effect on reading | |
1169 | and writing the @emph{contents} of files. | |
1170 | ||
1171 | @findex set-file-name-coding-system | |
1172 | @kindex C-x @key{RET} F | |
1173 | If you set the variable to a coding system name (as a Lisp symbol or | |
1174 | a string), Emacs encodes file names using that coding system for all | |
1175 | file operations. This makes it possible to use non-@acronym{ASCII} | |
1176 | characters in file names---or, at least, those non-@acronym{ASCII} | |
1177 | characters which the specified coding system can encode. Use @kbd{C-x | |
1178 | @key{RET} F} (@code{set-file-name-coding-system}) to specify this | |
1179 | interactively. | |
1180 | ||
1181 | If @code{file-name-coding-system} is @code{nil}, Emacs uses a | |
1182 | default coding system determined by the selected language environment. | |
ad36c422 CY |
1183 | In the default language environment, non-@acronym{ASCII} characters in |
1184 | file names are not encoded specially; they appear in the file system | |
1185 | using the internal Emacs representation. | |
8cf51b2c GM |
1186 | |
1187 | @strong{Warning:} if you change @code{file-name-coding-system} (or the | |
1188 | language environment) in the middle of an Emacs session, problems can | |
1189 | result if you have already visited files whose names were encoded using | |
1190 | the earlier coding system and cannot be encoded (or are encoded | |
1191 | differently) under the new coding system. If you try to save one of | |
1192 | these buffers under the visited file name, saving may use the wrong file | |
1193 | name, or it may get an error. If such a problem happens, use @kbd{C-x | |
1194 | C-w} to specify a new file name for that buffer. | |
1195 | ||
1196 | @findex recode-file-name | |
1197 | If a mistake occurs when encoding a file name, use the command | |
1198 | @kbd{M-x recode-file-name} to change the file name's coding | |
1199 | system. This prompts for an existing file name, its old coding | |
1200 | system, and the coding system to which you wish to convert. | |
1201 | ||
1202 | @node Terminal Coding | |
1203 | @section Coding Systems for Terminal I/O | |
1204 | ||
1205 | @table @kbd | |
1206 | @item C-x @key{RET} k @var{coding} @key{RET} | |
1207 | Use coding system @var{coding} for keyboard input. | |
1208 | ||
1209 | @item C-x @key{RET} t @var{coding} @key{RET} | |
1210 | Use coding system @var{coding} for terminal output. | |
1211 | @end table | |
1212 | ||
1213 | @kindex C-x RET t | |
1214 | @findex set-terminal-coding-system | |
1215 | The command @kbd{C-x @key{RET} t} (@code{set-terminal-coding-system}) | |
1216 | specifies the coding system for terminal output. If you specify a | |
1217 | character code for terminal output, all characters output to the | |
1218 | terminal are translated into that coding system. | |
1219 | ||
1220 | This feature is useful for certain character-only terminals built to | |
1221 | support specific languages or character sets---for example, European | |
1222 | terminals that support one of the ISO Latin character sets. You need to | |
1223 | specify the terminal coding system when using multibyte text, so that | |
1224 | Emacs knows which characters the terminal can actually handle. | |
1225 | ||
1226 | By default, output to the terminal is not translated at all, unless | |
1227 | Emacs can deduce the proper coding system from your terminal type or | |
1228 | your locale specification (@pxref{Language Environments}). | |
1229 | ||
1230 | @kindex C-x RET k | |
1231 | @findex set-keyboard-coding-system | |
1232 | @vindex keyboard-coding-system | |
1233 | The command @kbd{C-x @key{RET} k} (@code{set-keyboard-coding-system}) | |
1234 | or the variable @code{keyboard-coding-system} specifies the coding | |
1235 | system for keyboard input. Character-code translation of keyboard | |
1236 | input is useful for terminals with keys that send non-@acronym{ASCII} | |
1237 | graphic characters---for example, some terminals designed for ISO | |
1238 | Latin-1 or subsets of it. | |
1239 | ||
1240 | By default, keyboard input is translated based on your system locale | |
1241 | setting. If your terminal does not really support the encoding | |
1242 | implied by your locale (for example, if you find it inserts a | |
1243 | non-@acronym{ASCII} character if you type @kbd{M-i}), you will need to set | |
1244 | @code{keyboard-coding-system} to @code{nil} to turn off encoding. | |
1245 | You can do this by putting | |
1246 | ||
1247 | @lisp | |
1248 | (set-keyboard-coding-system nil) | |
1249 | @end lisp | |
1250 | ||
1251 | @noindent | |
ad36c422 | 1252 | in your init file. |
8cf51b2c GM |
1253 | |
1254 | There is a similarity between using a coding system translation for | |
1255 | keyboard input, and using an input method: both define sequences of | |
1256 | keyboard input that translate into single characters. However, input | |
1257 | methods are designed to be convenient for interactive use by humans, and | |
1258 | the sequences that are translated are typically sequences of @acronym{ASCII} | |
1259 | printing characters. Coding systems typically translate sequences of | |
1260 | non-graphic characters. | |
1261 | ||
1262 | @node Fontsets | |
1263 | @section Fontsets | |
1264 | @cindex fontsets | |
1265 | ||
1266 | A font typically defines shapes for a single alphabet or script. | |
1267 | Therefore, displaying the entire range of scripts that Emacs supports | |
1268 | requires a collection of many fonts. In Emacs, such a collection is | |
b545ff9c JR |
1269 | called a @dfn{fontset}. A fontset is defined by a list of font specs, |
1270 | each assigned to handle a range of character codes, and may fall back | |
1271 | on another fontset for characters which are not covered by the fonts | |
1272 | it specifies. | |
8cf51b2c GM |
1273 | |
1274 | Each fontset has a name, like a font. However, while fonts are | |
1275 | stored in the system and the available font names are defined by the | |
1276 | system, fontsets are defined within Emacs itself. Once you have | |
1277 | defined a fontset, you can use it within Emacs by specifying its name, | |
1278 | anywhere that you could use a single font. Of course, Emacs fontsets | |
1279 | can use only the fonts that the system supports; if certain characters | |
1280 | appear on the screen as hollow boxes, this means that the fontset in | |
1281 | use for them has no font for those characters.@footnote{The Emacs | |
1282 | installation instructions have information on additional font | |
1283 | support.} | |
1284 | ||
b545ff9c JR |
1285 | Emacs creates three fontsets automatically: the @dfn{standard |
1286 | fontset}, the @dfn{startup fontset} and the @dfn{default fontset}. | |
1287 | The default fontset is most likely to have fonts for a wide variety of | |
1288 | non-@acronym{ASCII} characters and is the default fallback for the | |
1289 | other two fontsets, and if you set a default font rather than fontset. | |
1290 | However it does not specify font family names, so results can be | |
a4bead12 JR |
1291 | somewhat random if you use it directly. You can specify use of a |
1292 | specific fontset with the @samp{-fn} option. For example, | |
8cf51b2c GM |
1293 | |
1294 | @example | |
1295 | emacs -fn fontset-standard | |
1296 | @end example | |
1297 | ||
1298 | @noindent | |
1299 | You can also specify a fontset with the @samp{Font} resource (@pxref{X | |
1300 | Resources}). | |
1301 | ||
a4bead12 JR |
1302 | If no fontset is specified for use, then Emacs uses an |
1303 | @acronym{ASCII} font, with @samp{fontset-default} as a fallback for | |
1304 | characters the font does not cover. The standard fontset is only used if | |
1305 | explicitly requested, despite its name. | |
1306 | ||
8cf51b2c | 1307 | A fontset does not necessarily specify a font for every character |
0eb025fb EZ |
1308 | code. If a fontset specifies no font for a certain character, or if |
1309 | it specifies a font that does not exist on your system, then it cannot | |
1310 | display that character properly. It will display that character as a | |
0088729a | 1311 | hex code or thin space or an empty box instead. (@xref{Text Display, , |
0eb025fb | 1312 | glyphless characters}, for details.) |
8cf51b2c GM |
1313 | |
1314 | @node Defining Fontsets | |
1315 | @section Defining fontsets | |
1316 | ||
1317 | @vindex standard-fontset-spec | |
b545ff9c JR |
1318 | @vindex w32-standard-fontset-spec |
1319 | @vindex ns-standard-fontset-spec | |
8cf51b2c | 1320 | @cindex standard fontset |
b545ff9c | 1321 | When running on X, Emacs creates a standard fontset automatically according to the value |
8cf51b2c GM |
1322 | of @code{standard-fontset-spec}. This fontset's name is |
1323 | ||
1324 | @example | |
1325 | -*-fixed-medium-r-normal-*-16-*-*-*-*-*-fontset-standard | |
1326 | @end example | |
1327 | ||
1328 | @noindent | |
1329 | or just @samp{fontset-standard} for short. | |
1330 | ||
b545ff9c JR |
1331 | On GNUstep and Mac, fontset-standard is created using the value of |
1332 | @code{ns-standard-fontset-spec}, and on Windows it is | |
1333 | created using the value of @code{w32-standard-fontset-spec}. | |
1334 | ||
8cf51b2c GM |
1335 | Bold, italic, and bold-italic variants of the standard fontset are |
1336 | created automatically. Their names have @samp{bold} instead of | |
1337 | @samp{medium}, or @samp{i} instead of @samp{r}, or both. | |
1338 | ||
1339 | @cindex startup fontset | |
b545ff9c JR |
1340 | Emacs generates a fontset automatically, based on any default |
1341 | @acronym{ASCII} font that you specify with the @samp{Font} resource or | |
1342 | the @samp{-fn} argument, or the default font that Emacs found when it | |
1343 | started. This is the @dfn{startup fontset} and its name is | |
1344 | @code{fontset-startup}. It does this by replacing the | |
1345 | @var{charset_registry} field with @samp{fontset}, and replacing | |
1346 | @var{charset_encoding} field with @samp{startup}, then using the | |
1347 | resulting string to specify a fontset. | |
8cf51b2c GM |
1348 | |
1349 | For instance, if you start Emacs this way, | |
1350 | ||
1351 | @example | |
1352 | emacs -fn "*courier-medium-r-normal--14-140-*-iso8859-1" | |
1353 | @end example | |
1354 | ||
1355 | @noindent | |
1356 | Emacs generates the following fontset and uses it for the initial X | |
1357 | window frame: | |
1358 | ||
1359 | @example | |
b545ff9c | 1360 | -*-courier-medium-r-normal-*-14-140-*-*-*-*-fontset-startup |
8cf51b2c GM |
1361 | @end example |
1362 | ||
b545ff9c JR |
1363 | The startup fontset will use the font that you specify or a variant |
1364 | with a different registry and encoding for all the characters which | |
1365 | are supported by that font, and fallback on @samp{fontset-default} for | |
1366 | other characters. | |
1367 | ||
8cf51b2c GM |
1368 | With the X resource @samp{Emacs.Font}, you can specify a fontset name |
1369 | just like an actual font name. But be careful not to specify a fontset | |
1370 | name in a wildcard resource like @samp{Emacs*Font}---that wildcard | |
1371 | specification matches various other resources, such as for menus, and | |
1372 | menus cannot handle fontsets. | |
1373 | ||
1374 | You can specify additional fontsets using X resources named | |
1375 | @samp{Fontset-@var{n}}, where @var{n} is an integer starting from 0. | |
1376 | The resource value should have this form: | |
1377 | ||
1378 | @smallexample | |
1379 | @var{fontpattern}, @r{[}@var{charset}:@var{font}@r{]@dots{}} | |
1380 | @end smallexample | |
1381 | ||
1382 | @noindent | |
1383 | @var{fontpattern} should have the form of a standard X font name, except | |
1384 | for the last two fields. They should have the form | |
1385 | @samp{fontset-@var{alias}}. | |
1386 | ||
1387 | The fontset has two names, one long and one short. The long name is | |
1388 | @var{fontpattern}. The short name is @samp{fontset-@var{alias}}. You | |
1389 | can refer to the fontset by either name. | |
1390 | ||
1391 | The construct @samp{@var{charset}:@var{font}} specifies which font to | |
1392 | use (in this fontset) for one particular character set. Here, | |
1393 | @var{charset} is the name of a character set, and @var{font} is the | |
1394 | font to use for that character set. You can use this construct any | |
1395 | number of times in defining one fontset. | |
1396 | ||
1397 | For the other character sets, Emacs chooses a font based on | |
1398 | @var{fontpattern}. It replaces @samp{fontset-@var{alias}} with values | |
1399 | that describe the character set. For the @acronym{ASCII} character font, | |
1400 | @samp{fontset-@var{alias}} is replaced with @samp{ISO8859-1}. | |
1401 | ||
1402 | In addition, when several consecutive fields are wildcards, Emacs | |
1403 | collapses them into a single wildcard. This is to prevent use of | |
1404 | auto-scaled fonts. Fonts made by scaling larger fonts are not usable | |
1405 | for editing, and scaling a smaller font is not useful because it is | |
1406 | better to use the smaller font in its own size, which is what Emacs | |
1407 | does. | |
1408 | ||
1409 | Thus if @var{fontpattern} is this, | |
1410 | ||
1411 | @example | |
1412 | -*-fixed-medium-r-normal-*-24-*-*-*-*-*-fontset-24 | |
1413 | @end example | |
1414 | ||
1415 | @noindent | |
1416 | the font specification for @acronym{ASCII} characters would be this: | |
1417 | ||
1418 | @example | |
1419 | -*-fixed-medium-r-normal-*-24-*-ISO8859-1 | |
1420 | @end example | |
1421 | ||
1422 | @noindent | |
1423 | and the font specification for Chinese GB2312 characters would be this: | |
1424 | ||
1425 | @example | |
1426 | -*-fixed-medium-r-normal-*-24-*-gb2312*-* | |
1427 | @end example | |
1428 | ||
1429 | You may not have any Chinese font matching the above font | |
1430 | specification. Most X distributions include only Chinese fonts that | |
1431 | have @samp{song ti} or @samp{fangsong ti} in @var{family} field. In | |
1432 | such a case, @samp{Fontset-@var{n}} can be specified as below: | |
1433 | ||
1434 | @smallexample | |
1435 | Emacs.Fontset-0: -*-fixed-medium-r-normal-*-24-*-*-*-*-*-fontset-24,\ | |
1436 | chinese-gb2312:-*-*-medium-r-normal-*-24-*-gb2312*-* | |
1437 | @end smallexample | |
1438 | ||
1439 | @noindent | |
1440 | Then, the font specifications for all but Chinese GB2312 characters have | |
1441 | @samp{fixed} in the @var{family} field, and the font specification for | |
1442 | Chinese GB2312 characters has a wild card @samp{*} in the @var{family} | |
1443 | field. | |
1444 | ||
1445 | @findex create-fontset-from-fontset-spec | |
1446 | The function that processes the fontset resource value to create the | |
1447 | fontset is called @code{create-fontset-from-fontset-spec}. You can also | |
1448 | call this function explicitly to create a fontset. | |
1449 | ||
d68eb23c | 1450 | @xref{Fonts}, for more information about font naming. |
8cf51b2c | 1451 | |
b545ff9c JR |
1452 | @node Modifying Fontsets |
1453 | @section Modifying Fontsets | |
1454 | @cindex fontsets, modifying | |
1455 | @findex set-fontset-font | |
1456 | ||
1457 | Fontsets do not always have to be created from scratch. If only | |
1458 | minor changes are required it may be easier to modify an existing | |
1459 | fontset. Modifying @samp{fontset-default} will also affect other | |
1460 | fontsets that use it as a fallback, so can be an effective way of | |
1461 | fixing problems with the fonts that Emacs chooses for a particular | |
1462 | script. | |
1463 | ||
1464 | Fontsets can be modified using the function @code{set-fontset-font}, | |
1465 | specifying a character, a charset, a script, or a range of characters | |
1466 | to modify the font for, and a font-spec for the font to be used. Some | |
1467 | examples are: | |
1468 | ||
1469 | @example | |
1470 | ;; Use Liberation Mono for latin-3 charset. | |
1471 | (set-fontset-font "fontset-default" 'iso-8859-3 "Liberation Mono") | |
1472 | ||
1473 | ;; Prefer a big5 font for han characters | |
1474 | (set-fontset-font "fontset-default" 'han (font-spec :registry "big5") | |
1475 | nil 'prepend) | |
1476 | ||
1477 | ;; Use DejaVu Sans Mono as a fallback in fontset-startup before | |
1478 | ;; resorting to fontset-default. | |
1479 | (set-fontset-font "fontset-startup" nil "DejaVu Sans Mono" nil 'append) | |
1480 | ||
1481 | ;; Use MyPrivateFont for the Unicode private use area. | |
1482 | (set-fontset-font "fontset-default" '(#xe000 . #xf8ff) "MyPrivateFont") | |
1483 | ||
1484 | @end example | |
1485 | ||
1486 | ||
8cf51b2c GM |
1487 | @node Undisplayable Characters |
1488 | @section Undisplayable Characters | |
1489 | ||
1490 | There may be a some non-@acronym{ASCII} characters that your terminal cannot | |
1491 | display. Most text-only terminals support just a single character | |
1492 | set (use the variable @code{default-terminal-coding-system} | |
1493 | (@pxref{Terminal Coding}) to tell Emacs which one); characters which | |
1494 | can't be encoded in that coding system are displayed as @samp{?} by | |
1495 | default. | |
1496 | ||
1497 | Graphical displays can display a broader range of characters, but | |
1498 | you may not have fonts installed for all of them; characters that have | |
1499 | no font appear as a hollow box. | |
1500 | ||
1501 | If you use Latin-1 characters but your terminal can't display | |
1502 | Latin-1, you can arrange to display mnemonic @acronym{ASCII} sequences | |
1503 | instead, e.g.@: @samp{"o} for o-umlaut. Load the library | |
1504 | @file{iso-ascii} to do this. | |
1505 | ||
1506 | @vindex latin1-display | |
1507 | If your terminal can display Latin-1, you can display characters | |
1508 | from other European character sets using a mixture of equivalent | |
1509 | Latin-1 characters and @acronym{ASCII} mnemonics. Customize the variable | |
1510 | @code{latin1-display} to enable this. The mnemonic @acronym{ASCII} | |
1511 | sequences mostly correspond to those of the prefix input methods. | |
1512 | ||
1513 | @node Unibyte Mode | |
1514 | @section Unibyte Editing Mode | |
1515 | ||
1516 | @cindex European character sets | |
1517 | @cindex accented characters | |
1518 | @cindex ISO Latin character sets | |
1519 | @cindex Unibyte operation | |
1520 | The ISO 8859 Latin-@var{n} character sets define character codes in | |
1521 | the range 0240 to 0377 octal (160 to 255 decimal) to handle the | |
1522 | accented letters and punctuation needed by various European languages | |
43b3b4d1 EZ |
1523 | (and some non-European ones). Note that Emacs considers bytes with |
1524 | codes in this range as raw bytes, not as characters, even in a unibyte | |
1525 | session, i.e.@: if you disable multibyte characters. However, Emacs | |
1526 | can still handle these character codes as if they belonged to | |
1527 | @emph{one} of the single-byte character sets at a time. To specify | |
1528 | @emph{which} of these codes to use, invoke @kbd{M-x | |
8cf51b2c GM |
1529 | set-language-environment} and specify a suitable language environment |
1530 | such as @samp{Latin-@var{n}}. | |
1531 | ||
1532 | For more information about unibyte operation, see @ref{Enabling | |
1533 | Multibyte}. Note particularly that you probably want to ensure that | |
1534 | your initialization files are read as unibyte if they contain | |
1535 | non-@acronym{ASCII} characters. | |
1536 | ||
1537 | @vindex unibyte-display-via-language-environment | |
43b3b4d1 EZ |
1538 | Emacs can also display bytes in the range 160 to 255 as readable |
1539 | characters, provided the terminal or font in use supports them. This | |
1540 | works automatically. On a graphical display, Emacs can also display | |
1541 | single-byte characters through fontsets, in effect by displaying the | |
1542 | equivalent multibyte characters according to the current language | |
1543 | environment. To request this, set the variable | |
1544 | @code{unibyte-display-via-language-environment} to a non-@code{nil} | |
1545 | value. Note that setting this only affects how these bytes are | |
1546 | displayed, but does not change the fundamental fact that Emacs treats | |
1547 | them as raw bytes, not as characters. | |
8cf51b2c GM |
1548 | |
1549 | @cindex @code{iso-ascii} library | |
1550 | If your terminal does not support display of the Latin-1 character | |
1551 | set, Emacs can display these characters as @acronym{ASCII} sequences which at | |
1552 | least give you a clear idea of what the characters are. To do this, | |
1553 | load the library @code{iso-ascii}. Similar libraries for other | |
1554 | Latin-@var{n} character sets could be implemented, but we don't have | |
1555 | them yet. | |
1556 | ||
1557 | @findex standard-display-8bit | |
1558 | @cindex 8-bit display | |
1559 | Normally non-ISO-8859 characters (decimal codes between 128 and 159 | |
1560 | inclusive) are displayed as octal escapes. You can change this for | |
1561 | non-standard ``extended'' versions of ISO-8859 character sets by using the | |
1562 | function @code{standard-display-8bit} in the @code{disp-table} library. | |
1563 | ||
1564 | There are two ways to input single-byte non-@acronym{ASCII} | |
1565 | characters: | |
1566 | ||
1567 | @itemize @bullet | |
1568 | @cindex 8-bit input | |
1569 | @item | |
1570 | You can use an input method for the selected language environment. | |
1571 | @xref{Input Methods}. When you use an input method in a unibyte buffer, | |
1572 | the non-@acronym{ASCII} character you specify with it is converted to unibyte. | |
1573 | ||
1574 | @item | |
1575 | If your keyboard can generate character codes 128 (decimal) and up, | |
1576 | representing non-@acronym{ASCII} characters, you can type those character codes | |
1577 | directly. | |
1578 | ||
1579 | On a graphical display, you should not need to do anything special to use | |
1580 | these keys; they should simply work. On a text-only terminal, you | |
1581 | should use the command @code{M-x set-keyboard-coding-system} or the | |
1582 | variable @code{keyboard-coding-system} to specify which coding system | |
1583 | your keyboard uses (@pxref{Terminal Coding}). Enabling this feature | |
1584 | will probably require you to use @kbd{ESC} to type Meta characters; | |
1585 | however, on a console terminal or in @code{xterm}, you can arrange for | |
1586 | Meta to be converted to @kbd{ESC} and still be able type 8-bit | |
1587 | characters present directly on the keyboard or using @kbd{Compose} or | |
1588 | @kbd{AltGr} keys. @xref{User Input}. | |
1589 | ||
1590 | @kindex C-x 8 | |
1591 | @cindex @code{iso-transl} library | |
1592 | @cindex compose character | |
1593 | @cindex dead character | |
1594 | @item | |
1595 | For Latin-1 only, you can use the key @kbd{C-x 8} as a ``compose | |
1596 | character'' prefix for entry of non-@acronym{ASCII} Latin-1 printing | |
1597 | characters. @kbd{C-x 8} is good for insertion (in the minibuffer as | |
1598 | well as other buffers), for searching, and in any other context where | |
1599 | a key sequence is allowed. | |
1600 | ||
1601 | @kbd{C-x 8} works by loading the @code{iso-transl} library. Once that | |
1602 | library is loaded, the @key{ALT} modifier key, if the keyboard has | |
1603 | one, serves the same purpose as @kbd{C-x 8}: use @key{ALT} together | |
1604 | with an accent character to modify the following letter. In addition, | |
1605 | if the keyboard has keys for the Latin-1 ``dead accent characters,'' | |
1606 | they too are defined to compose with the following character, once | |
1607 | @code{iso-transl} is loaded. | |
1608 | ||
1609 | Use @kbd{C-x 8 C-h} to list all the available @kbd{C-x 8} translations. | |
1610 | @end itemize | |
1611 | ||
1612 | @node Charsets | |
1613 | @section Charsets | |
1614 | @cindex charsets | |
1615 | ||
18430066 CY |
1616 | In Emacs, @dfn{charset} is short for ``character set''. Emacs |
1617 | supports most popular charsets (such as @code{ascii}, | |
1618 | @code{iso-8859-1}, @code{cp1250}, @code{big5}, and @code{unicode}), in | |
1619 | addition to some charsets of its own (such as @code{emacs}, | |
1620 | @code{unicode-bmp}, and @code{eight-bit}). All supported characters | |
1621 | belong to one or more charsets. | |
1622 | ||
1623 | Emacs normally ``does the right thing'' with respect to charsets, so | |
1624 | that you don't have to worry about them. However, it is sometimes | |
1625 | helpful to know some of the underlying details about charsets. | |
1626 | ||
d68eb23c | 1627 | One example is font selection (@pxref{Fonts}). Each language |
18430066 CY |
1628 | environment (@pxref{Language Environments}) defines a ``priority |
1629 | list'' for the various charsets. When searching for a font, Emacs | |
1630 | initially attempts to find one that can display the highest-priority | |
1631 | charsets. For instance, in the Japanese language environment, the | |
1632 | charset @code{japanese-jisx0208} has the highest priority, so Emacs | |
1633 | tries to use a font whose @code{registry} property is | |
1634 | @samp{JISX0208.1983-0}. | |
8cf51b2c GM |
1635 | |
1636 | @findex list-charset-chars | |
1637 | @cindex characters in a certain charset | |
1638 | @findex describe-character-set | |
18430066 | 1639 | There are two commands that can be used to obtain information about |
3af970a0 KH |
1640 | charsets. The command @kbd{M-x list-charset-chars} prompts for a |
1641 | charset name, and displays all the characters in that character set. | |
1642 | The command @kbd{M-x describe-character-set} prompts for a charset | |
18430066 | 1643 | name, and displays information about that charset, including its |
3af970a0 KH |
1644 | internal representation within Emacs. |
1645 | ||
1646 | @findex list-character-sets | |
18430066 | 1647 | To display a list of all supported charsets, type @kbd{M-x |
3af970a0 | 1648 | list-character-sets}. The list gives the names of charsets and |
18430066 CY |
1649 | additional information to identity each charset (see |
1650 | @url{http://www.itscj.ipsj.or.jp/ISO-IR/} for details). In this list, | |
1651 | charsets are divided into two categories: @dfn{normal charsets} are | |
1652 | listed first, followed by @dfn{supplementary charsets}. A | |
1653 | supplementary charset is one that is used to define another charset | |
1654 | (as a parent or a subset), or to provide backward-compatibility for | |
1655 | older Emacs versions. | |
1656 | ||
1657 | To find out which charset a character in the buffer belongs to, put | |
1658 | point before it and type @kbd{C-u C-x =} (@pxref{International | |
1659 | Chars}). | |
8cf51b2c | 1660 | |
f4b6ba46 EZ |
1661 | @node Bidirectional Editing |
1662 | @section Bidirectional Editing | |
1663 | @cindex bidirectional editing | |
1664 | @cindex right-to-left text | |
1665 | ||
1666 | Emacs supports editing text written in scripts, such as Arabic and | |
1667 | Hebrew, whose natural ordering of horizontal text for display is from | |
1668 | right to left. However, digits and Latin text embedded in these | |
1669 | scripts are still displayed left to right. It is also not uncommon to | |
1670 | have small portions of text in Arabic or Hebrew embedded in otherwise | |
1671 | Latin document, e.g., as comments and strings in a program source | |
1672 | file. For these reasons, text that uses these scripts is actually | |
1673 | @dfn{bidirectional}: a mixture of runs of left-to-right and | |
1674 | right-to-left characters. | |
1675 | ||
1676 | This section describes the facilities and options provided by Emacs | |
1677 | for editing bidirectional text. | |
1678 | ||
1679 | @cindex logical order | |
1680 | @cindex visual order | |
1681 | Emacs stores right-to-left and bidirectional text in the so-called | |
1682 | @dfn{logical} (or @dfn{reading}) order: the buffer or string position | |
1683 | of the first character you read precedes that of the next character. | |
1684 | Reordering of bidirectional text into the @dfn{visual} order happens | |
1685 | at display time. As result, character positions no longer increase | |
1686 | monotonically with their positions on display. Emacs implements the | |
1687 | Unicode Bidirectional Algorithm described in the Unicode Standard | |
1688 | Annex #9, for reordering of bidirectional text for display. | |
1689 | ||
1690 | @vindex bidi-display-reordering | |
1691 | The buffer-local variable @code{bidi-display-reordering} controls | |
1692 | whether text in the buffer is reordered for display. If its value is | |
1693 | non-@code{nil}, Emacs reorders characters that have right-to-left | |
1694 | directionality when they are displayed. The default value is | |
1695 | @code{nil}. | |
1696 | ||
1697 | Each paragraph of bidirectional text can have its own @dfn{base | |
1698 | direction}, either right-to-left or left-to-right. (Paragraph | |
1699 | boundaries are defined by the regular expressions | |
1700 | @code{paragraph-start} and @code{paragraph-separate}, see | |
1701 | @ref{Paragraphs}.) Text in left-to-right paragraphs begins at the | |
1702 | left margin of the window and is truncated or continued when it | |
1703 | reaches the right margin. By contrast, text in right-to-left | |
1704 | paragraphs begins at the right margin and is continued or truncated at | |
1705 | the left margin. | |
1706 | ||
1707 | @vindex bidi-paragraph-direction | |
1708 | Emacs determines the base direction of each paragraph dynamically, | |
1709 | based on the text at the beginning of the paragraph. However, | |
1710 | sometimes a buffer may need to force a certain base direction for its | |
1711 | paragraphs. The variable @code{bidi-paragraph-direction}, if | |
1712 | non-@code{nil}, disables the dynamic determination of the base | |
1713 | direction, and instead forces all paragraphs in the buffer to have the | |
1714 | direction specified by its buffer-local value. The value can be either | |
1715 | @code{right-to-left} or @code{left-to-right}. Any other value is | |
1716 | interpreted as @code{nil}. | |
1717 | ||
1718 | @cindex LRM | |
1719 | @cindex RLM | |
1720 | Alternatively, you can control the base direction of a paragraph by | |
1721 | inserting special formatting characters in front of the paragraph. | |
1722 | The special character @code{RIGHT-TO-LEFT MARK}, or @sc{rlm}, forces | |
1723 | the right-to-left direction on the following paragraph, while | |
1724 | @code{LEFT-TO-RIGHT MARK}, or @sc{lrm} forces the left-to-right | |
1725 | direction. (You can use @kbd{C-x 8 RET} to insert these characters.) | |
1726 | In a GUI session, the @sc{lrm} and @sc{rlm} characters display as | |
1727 | blanks. | |
1728 | ||
1729 | Because characters are reordered for display, Emacs commands that | |
1730 | operate in the logical order or on stretches of buffer positions may | |
1731 | produce unusual effects. For example, @kbd{C-f} and @kbd{C-b} | |
1732 | commands move point in the logical order, so the cursor will sometimes | |
1733 | jump when point traverses reordered bidirectional text. Similarly, a | |
1734 | highlighted region covering a contiguous range of character positions | |
1735 | may look discontinuous if the region spans reordered text. This is | |
1736 | normal and similar to behavior of other programs that support | |
1737 | bidirectional text. |