| 1 | @c This is part of the Emacs manual. |
| 2 | @c Copyright (C) 1997, 1999-2013 Free Software Foundation, Inc. |
| 3 | @c See file emacs.texi for copying conditions. |
| 4 | @node International |
| 5 | @chapter International Character Set Support |
| 6 | @c This node is referenced in the tutorial. When renaming or deleting |
| 7 | @c it, the tutorial needs to be adjusted. (TUTORIAL.de) |
| 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 that are 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 |
| 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 | |
| 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 | |
| 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 chose |
| 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 | With the X Window System, your locale should be set to an appropriate |
| 85 | value 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 | * Language Environments:: Setting things up for the language you use. |
| 94 | * Input Methods:: Entering text characters not on your keyboard. |
| 95 | * Select Input Method:: Specifying your choice of input methods. |
| 96 | * Coding Systems:: Character set conversion when you read and |
| 97 | write files, and so on. |
| 98 | * Recognize Coding:: How Emacs figures out which conversion to use. |
| 99 | * Specify Coding:: Specifying a file's coding system explicitly. |
| 100 | * Output Coding:: Choosing coding systems for output. |
| 101 | * Text Coding:: Choosing conversion to use for file text. |
| 102 | * Communication Coding:: Coding systems for interprocess communication. |
| 103 | * File Name Coding:: Coding systems for file @emph{names}. |
| 104 | * Terminal Coding:: Specifying coding systems for converting |
| 105 | terminal input and output. |
| 106 | * Fontsets:: Fontsets are collections of fonts |
| 107 | that cover the whole spectrum of characters. |
| 108 | * Defining Fontsets:: Defining a new fontset. |
| 109 | * Modifying Fontsets:: Modifying an existing fontset. |
| 110 | * Undisplayable Characters:: When characters don't display. |
| 111 | * Unibyte Mode:: You can pick one European character set |
| 112 | to use without multibyte characters. |
| 113 | * Charsets:: How Emacs groups its internal character codes. |
| 114 | * Bidirectional Editing:: Support for right-to-left scripts. |
| 115 | @end menu |
| 116 | |
| 117 | @node International Chars |
| 118 | @section Introduction to International Character Sets |
| 119 | |
| 120 | The users of international character sets and scripts have |
| 121 | established many more-or-less standard coding systems for storing |
| 122 | files. These coding systems are typically @dfn{multibyte}, meaning |
| 123 | that sequences of two or more bytes are used to represent individual |
| 124 | non-@acronym{ASCII} characters. |
| 125 | |
| 126 | @cindex Unicode |
| 127 | Internally, Emacs uses its own multibyte character encoding, which |
| 128 | is a superset of the @dfn{Unicode} standard. This internal encoding |
| 129 | allows characters from almost every known script to be intermixed in a |
| 130 | single buffer or string. Emacs translates between the multibyte |
| 131 | character encoding and various other coding systems when reading and |
| 132 | writing files, and when exchanging data with subprocesses. |
| 133 | |
| 134 | @kindex C-h h |
| 135 | @findex view-hello-file |
| 136 | @cindex undisplayable characters |
| 137 | @cindex @samp{?} in display |
| 138 | The command @kbd{C-h h} (@code{view-hello-file}) displays the file |
| 139 | @file{etc/HELLO}, which illustrates various scripts by showing |
| 140 | how to say ``hello'' in many languages. If some characters can't be |
| 141 | displayed on your terminal, they appear as @samp{?} or as hollow boxes |
| 142 | (@pxref{Undisplayable Characters}). |
| 143 | |
| 144 | Keyboards, even in the countries where these character sets are |
| 145 | used, generally don't have keys for all the characters in them. You |
| 146 | can insert characters that your keyboard does not support, using |
| 147 | @kbd{C-q} (@code{quoted-insert}) or @kbd{C-x 8 @key{RET}} |
| 148 | (@code{insert-char}). @xref{Inserting Text}. Emacs also supports |
| 149 | various @dfn{input methods}, typically one for each script or |
| 150 | language, which make it easier to type characters in the script. |
| 151 | @xref{Input Methods}. |
| 152 | |
| 153 | @kindex C-x RET |
| 154 | The prefix key @kbd{C-x @key{RET}} is used for commands that pertain |
| 155 | to multibyte characters, coding systems, and input methods. |
| 156 | |
| 157 | @kindex C-x = |
| 158 | @findex what-cursor-position |
| 159 | The command @kbd{C-x =} (@code{what-cursor-position}) shows |
| 160 | information about the character at point. In addition to the |
| 161 | character position, which was described in @ref{Position Info}, this |
| 162 | command displays how the character is encoded. For instance, it |
| 163 | displays the following line in the echo area for the character |
| 164 | @samp{c}: |
| 165 | |
| 166 | @smallexample |
| 167 | Char: c (99, #o143, #x63) point=28062 of 36168 (78%) column=53 |
| 168 | @end smallexample |
| 169 | |
| 170 | The four values after @samp{Char:} describe the character that |
| 171 | follows point, first by showing it and then by giving its character |
| 172 | code in decimal, octal and hex. For a non-@acronym{ASCII} multibyte |
| 173 | character, these are followed by @samp{file} and the character's |
| 174 | representation, in hex, in the buffer's coding system, if that coding |
| 175 | system encodes the character safely and with a single byte |
| 176 | (@pxref{Coding Systems}). If the character's encoding is longer than |
| 177 | one byte, Emacs shows @samp{file ...}. |
| 178 | |
| 179 | As a special case, if the character lies in the range 128 (0200 |
| 180 | octal) through 159 (0237 octal), it stands for a ``raw'' byte that |
| 181 | does not correspond to any specific displayable character. Such a |
| 182 | ``character'' lies within the @code{eight-bit-control} character set, |
| 183 | and is displayed as an escaped octal character code. In this case, |
| 184 | @kbd{C-x =} shows @samp{part of display ...} instead of @samp{file}. |
| 185 | |
| 186 | @cindex character set of character at point |
| 187 | @cindex font of character at point |
| 188 | @cindex text properties at point |
| 189 | @cindex face at point |
| 190 | With a prefix argument (@kbd{C-u C-x =}), this command displays a |
| 191 | detailed description of the character in a window: |
| 192 | |
| 193 | @itemize @bullet |
| 194 | @item |
| 195 | The character set name, and the codes that identify the character |
| 196 | within that character set; @acronym{ASCII} characters are identified |
| 197 | as belonging to the @code{ascii} character set. |
| 198 | |
| 199 | @item |
| 200 | The character's syntax and categories. |
| 201 | |
| 202 | @item |
| 203 | The character's encodings, both internally in the buffer, and externally |
| 204 | if you were to save the file. |
| 205 | |
| 206 | @item |
| 207 | What keys to type to input the character in the current input method |
| 208 | (if it supports the character). |
| 209 | |
| 210 | @item |
| 211 | If you are running Emacs on a graphical display, the font name and |
| 212 | glyph code for the character. If you are running Emacs on a text |
| 213 | terminal, the code(s) sent to the terminal. |
| 214 | |
| 215 | @item |
| 216 | The character's text properties (@pxref{Text Properties,,, |
| 217 | elisp, the Emacs Lisp Reference Manual}), including any non-default |
| 218 | faces used to display the character, and any overlays containing it |
| 219 | (@pxref{Overlays,,, elisp, the same manual}). |
| 220 | @end itemize |
| 221 | |
| 222 | Here's an example showing the Latin-1 character A with grave accent, |
| 223 | in a buffer whose coding system is @code{utf-8-unix}: |
| 224 | |
| 225 | @smallexample |
| 226 | position: 1 of 1 (0%), column: 0 |
| 227 | character: @`A (displayed as @`A) (codepoint 192, #o300, #xc0) |
| 228 | preferred charset: unicode (Unicode (ISO10646)) |
| 229 | code point in charset: 0xC0 |
| 230 | syntax: w which means: word |
| 231 | category: .:Base, L:Left-to-right (strong), |
| 232 | j:Japanese, l:Latin, v:Viet |
| 233 | buffer code: #xC3 #x80 |
| 234 | file code: not encodable by coding system undecided-unix |
| 235 | display: by this font (glyph code) |
| 236 | xft:-unknown-DejaVu Sans Mono-normal-normal- |
| 237 | normal-*-13-*-*-*-m-0-iso10646-1 (#x82) |
| 238 | |
| 239 | Character code properties: customize what to show |
| 240 | name: LATIN CAPITAL LETTER A WITH GRAVE |
| 241 | old-name: LATIN CAPITAL LETTER A GRAVE |
| 242 | general-category: Lu (Letter, Uppercase) |
| 243 | decomposition: (65 768) ('A' '`') |
| 244 | @end smallexample |
| 245 | |
| 246 | @node Language Environments |
| 247 | @section Language Environments |
| 248 | @cindex language environments |
| 249 | |
| 250 | All supported character sets are supported in Emacs buffers whenever |
| 251 | multibyte characters are enabled; there is no need to select a |
| 252 | particular language in order to display its characters. |
| 253 | However, it is important to select a @dfn{language |
| 254 | environment} in order to set various defaults. Roughly speaking, the |
| 255 | language environment represents a choice of preferred script rather |
| 256 | than a choice of language. |
| 257 | |
| 258 | The language environment controls which coding systems to recognize |
| 259 | when reading text (@pxref{Recognize Coding}). This applies to files, |
| 260 | incoming mail, and any other text you read into Emacs. It may also |
| 261 | specify the default coding system to use when you create a file. Each |
| 262 | language environment also specifies a default input method. |
| 263 | |
| 264 | @findex set-language-environment |
| 265 | @vindex current-language-environment |
| 266 | To select a language environment, customize |
| 267 | @code{current-language-environment} or use the command @kbd{M-x |
| 268 | set-language-environment}. It makes no difference which buffer is |
| 269 | current when you use this command, because the effects apply globally |
| 270 | to the Emacs session. The supported language environments |
| 271 | (see the variable @code{language-info-alist}) include: |
| 272 | |
| 273 | @cindex Euro sign |
| 274 | @cindex UTF-8 |
| 275 | @quotation |
| 276 | ASCII, Belarusian, Bengali, Brazilian Portuguese, Bulgarian, Cham, |
| 277 | Chinese-BIG5, Chinese-CNS, Chinese-EUC-TW, Chinese-GB, Chinese-GBK, |
| 278 | Chinese-GB18030, Croatian, Cyrillic-ALT, Cyrillic-ISO, Cyrillic-KOI8, |
| 279 | Czech, Devanagari, Dutch, English, Esperanto, Ethiopic, French, |
| 280 | Georgian, German, Greek, Gujarati, Hebrew, IPA, Italian, Japanese, |
| 281 | Kannada, Khmer, Korean, Lao, Latin-1, Latin-2, Latin-3, Latin-4, |
| 282 | Latin-5, Latin-6, Latin-7, Latin-8 (Celtic), Latin-9 (updated Latin-1 |
| 283 | with the Euro sign), Latvian, Lithuanian, Malayalam, Oriya, Polish, |
| 284 | Punjabi, Romanian, Russian, Sinhala, Slovak, Slovenian, Spanish, |
| 285 | Swedish, TaiViet, Tajik, Tamil, Telugu, Thai, Tibetan, Turkish, UTF-8 |
| 286 | (for a setup which prefers Unicode characters and files encoded in |
| 287 | UTF-8), Ukrainian, Vietnamese, Welsh, and Windows-1255 (for a setup |
| 288 | which prefers Cyrillic characters and files encoded in Windows-1255). |
| 289 | @end quotation |
| 290 | |
| 291 | To display the script(s) used by your language environment on a |
| 292 | graphical display, you need to have suitable fonts. |
| 293 | @xref{Fontsets}, for more details about setting up your fonts. |
| 294 | |
| 295 | @findex set-locale-environment |
| 296 | @vindex locale-language-names |
| 297 | @vindex locale-charset-language-names |
| 298 | @cindex locales |
| 299 | Some operating systems let you specify the character-set locale you |
| 300 | are using by setting the locale environment variables @env{LC_ALL}, |
| 301 | @env{LC_CTYPE}, or @env{LANG}. (If more than one of these is |
| 302 | set, the first one that is nonempty specifies your locale for this |
| 303 | purpose.) During startup, Emacs looks up your character-set locale's |
| 304 | name in the system locale alias table, matches its canonical name |
| 305 | against entries in the value of the variables |
| 306 | @code{locale-charset-language-names} and @code{locale-language-names} |
| 307 | (the former overrides the latter), |
| 308 | and selects the corresponding language environment if a match is found. |
| 309 | It also adjusts the display |
| 310 | table and terminal coding system, the locale coding system, the |
| 311 | preferred coding system as needed for the locale, and---last but not |
| 312 | least---the way Emacs decodes non-@acronym{ASCII} characters sent by your keyboard. |
| 313 | |
| 314 | @c This seems unlikely, doesn't it? |
| 315 | If you modify the @env{LC_ALL}, @env{LC_CTYPE}, or @env{LANG} |
| 316 | environment variables while running Emacs (by using @kbd{M-x setenv}), |
| 317 | you may want to invoke the @code{set-locale-environment} |
| 318 | function afterwards to readjust the language environment from the new |
| 319 | locale. |
| 320 | |
| 321 | @vindex locale-preferred-coding-systems |
| 322 | The @code{set-locale-environment} function normally uses the preferred |
| 323 | coding system established by the language environment to decode system |
| 324 | messages. But if your locale matches an entry in the variable |
| 325 | @code{locale-preferred-coding-systems}, Emacs uses the corresponding |
| 326 | coding system instead. For example, if the locale @samp{ja_JP.PCK} |
| 327 | matches @code{japanese-shift-jis} in |
| 328 | @code{locale-preferred-coding-systems}, Emacs uses that encoding even |
| 329 | though it might normally use @code{japanese-iso-8bit}. |
| 330 | |
| 331 | You can override the language environment chosen at startup with |
| 332 | explicit use of the command @code{set-language-environment}, or with |
| 333 | customization of @code{current-language-environment} in your init |
| 334 | file. |
| 335 | |
| 336 | @kindex C-h L |
| 337 | @findex describe-language-environment |
| 338 | To display information about the effects of a certain language |
| 339 | environment @var{lang-env}, use the command @kbd{C-h L @var{lang-env} |
| 340 | @key{RET}} (@code{describe-language-environment}). This tells you |
| 341 | which languages this language environment is useful for, and lists the |
| 342 | character sets, coding systems, and input methods that go with it. It |
| 343 | also shows some sample text to illustrate scripts used in this |
| 344 | language environment. If you give an empty input for @var{lang-env}, |
| 345 | this command describes the chosen language environment. |
| 346 | @anchor{Describe Language Environment} |
| 347 | |
| 348 | @vindex set-language-environment-hook |
| 349 | You can customize any language environment with the normal hook |
| 350 | @code{set-language-environment-hook}. The command |
| 351 | @code{set-language-environment} runs that hook after setting up the new |
| 352 | language environment. The hook functions can test for a specific |
| 353 | language environment by checking the variable |
| 354 | @code{current-language-environment}. This hook is where you should |
| 355 | put non-default settings for specific language environments, such as |
| 356 | coding systems for keyboard input and terminal output, the default |
| 357 | input method, etc. |
| 358 | |
| 359 | @vindex exit-language-environment-hook |
| 360 | Before it starts to set up the new language environment, |
| 361 | @code{set-language-environment} first runs the hook |
| 362 | @code{exit-language-environment-hook}. This hook is useful for undoing |
| 363 | customizations that were made with @code{set-language-environment-hook}. |
| 364 | For instance, if you set up a special key binding in a specific language |
| 365 | environment using @code{set-language-environment-hook}, you should set |
| 366 | up @code{exit-language-environment-hook} to restore the normal binding |
| 367 | for that key. |
| 368 | |
| 369 | @node Input Methods |
| 370 | @section Input Methods |
| 371 | |
| 372 | @cindex input methods |
| 373 | An @dfn{input method} is a kind of character conversion designed |
| 374 | specifically for interactive input. In Emacs, typically each language |
| 375 | has its own input method; sometimes several languages that use the same |
| 376 | characters can share one input method. A few languages support several |
| 377 | input methods. |
| 378 | |
| 379 | The simplest kind of input method works by mapping @acronym{ASCII} letters |
| 380 | into another alphabet; this allows you to use one other alphabet |
| 381 | instead of @acronym{ASCII}. The Greek and Russian input methods |
| 382 | work this way. |
| 383 | |
| 384 | A more powerful technique is composition: converting sequences of |
| 385 | characters into one letter. Many European input methods use composition |
| 386 | to produce a single non-@acronym{ASCII} letter from a sequence that consists of a |
| 387 | letter followed by accent characters (or vice versa). For example, some |
| 388 | methods convert the sequence @kbd{o ^} into a single accented letter. |
| 389 | These input methods have no special commands of their own; all they do |
| 390 | is compose sequences of printing characters. |
| 391 | |
| 392 | The input methods for syllabic scripts typically use mapping followed |
| 393 | by composition. The input methods for Thai and Korean work this way. |
| 394 | First, letters are mapped into symbols for particular sounds or tone |
| 395 | marks; then, sequences of these that make up a whole syllable are |
| 396 | mapped into one syllable sign. |
| 397 | |
| 398 | Chinese and Japanese require more complex methods. In Chinese input |
| 399 | methods, first you enter the phonetic spelling of a Chinese word (in |
| 400 | input method @code{chinese-py}, among others), or a sequence of |
| 401 | portions of the character (input methods @code{chinese-4corner} and |
| 402 | @code{chinese-sw}, and others). One input sequence typically |
| 403 | corresponds to many possible Chinese characters. You select the one |
| 404 | you mean using keys such as @kbd{C-f}, @kbd{C-b}, @kbd{C-n}, |
| 405 | @kbd{C-p} (or the arrow keys), and digits, which have special meanings |
| 406 | in this situation. |
| 407 | |
| 408 | The possible characters are conceptually arranged in several rows, |
| 409 | with each row holding up to 10 alternatives. Normally, Emacs displays |
| 410 | just one row at a time, in the echo area; @code{(@var{i}/@var{j})} |
| 411 | appears at the beginning, to indicate that this is the @var{i}th row |
| 412 | out of a total of @var{j} rows. Type @kbd{C-n} or @kbd{C-p} to |
| 413 | display the next row or the previous row. |
| 414 | |
| 415 | Type @kbd{C-f} and @kbd{C-b} to move forward and backward among |
| 416 | the alternatives in the current row. As you do this, Emacs highlights |
| 417 | the current alternative with a special color; type @code{C-@key{SPC}} |
| 418 | to select the current alternative and use it as input. The |
| 419 | alternatives in the row are also numbered; the number appears before |
| 420 | the alternative. Typing a number selects the associated alternative |
| 421 | of the current row and uses it as input. |
| 422 | |
| 423 | @key{TAB} in these Chinese input methods displays a buffer showing |
| 424 | all the possible characters at once; then clicking @kbd{Mouse-2} on |
| 425 | one of them selects that alternative. The keys @kbd{C-f}, @kbd{C-b}, |
| 426 | @kbd{C-n}, @kbd{C-p}, and digits continue to work as usual, but they |
| 427 | do the highlighting in the buffer showing the possible characters, |
| 428 | rather than in the echo area. |
| 429 | |
| 430 | In Japanese input methods, first you input a whole word using |
| 431 | phonetic spelling; then, after the word is in the buffer, Emacs |
| 432 | converts it into one or more characters using a large dictionary. One |
| 433 | phonetic spelling corresponds to a number of different Japanese words; |
| 434 | to select one of them, use @kbd{C-n} and @kbd{C-p} to cycle through |
| 435 | the alternatives. |
| 436 | |
| 437 | Sometimes it is useful to cut off input method processing so that the |
| 438 | characters you have just entered will not combine with subsequent |
| 439 | characters. For example, in input method @code{latin-1-postfix}, the |
| 440 | sequence @kbd{o ^} combines to form an @samp{o} with an accent. What if |
| 441 | you want to enter them as separate characters? |
| 442 | |
| 443 | One way is to type the accent twice; this is a special feature for |
| 444 | entering the separate letter and accent. For example, @kbd{o ^ ^} gives |
| 445 | you the two characters @samp{o^}. Another way is to type another letter |
| 446 | after the @kbd{o}---something that won't combine with that---and |
| 447 | immediately delete it. For example, you could type @kbd{o o @key{DEL} |
| 448 | ^} to get separate @samp{o} and @samp{^}. |
| 449 | |
| 450 | Another method, more general but not quite as easy to type, is to use |
| 451 | @kbd{C-\ C-\} between two characters to stop them from combining. This |
| 452 | is the command @kbd{C-\} (@code{toggle-input-method}) used twice. |
| 453 | @ifnottex |
| 454 | @xref{Select Input Method}. |
| 455 | @end ifnottex |
| 456 | |
| 457 | @cindex incremental search, input method interference |
| 458 | @kbd{C-\ C-\} is especially useful inside an incremental search, |
| 459 | because it stops waiting for more characters to combine, and starts |
| 460 | searching for what you have already entered. |
| 461 | |
| 462 | To find out how to input the character after point using the current |
| 463 | input method, type @kbd{C-u C-x =}. @xref{Position Info}. |
| 464 | |
| 465 | @vindex input-method-verbose-flag |
| 466 | @vindex input-method-highlight-flag |
| 467 | The variables @code{input-method-highlight-flag} and |
| 468 | @code{input-method-verbose-flag} control how input methods explain |
| 469 | what is happening. If @code{input-method-highlight-flag} is |
| 470 | non-@code{nil}, the partial sequence is highlighted in the buffer (for |
| 471 | most input methods---some disable this feature). If |
| 472 | @code{input-method-verbose-flag} is non-@code{nil}, the list of |
| 473 | possible characters to type next is displayed in the echo area (but |
| 474 | not when you are in the minibuffer). |
| 475 | |
| 476 | Another facility for typing characters not on your keyboard is by |
| 477 | using @kbd{C-x 8 @key{RET}} (@code{insert-char}) to insert a single |
| 478 | character based on its Unicode name or code-point; see @ref{Inserting |
| 479 | Text}. |
| 480 | |
| 481 | @node Select Input Method |
| 482 | @section Selecting an Input Method |
| 483 | |
| 484 | @table @kbd |
| 485 | @item C-\ |
| 486 | Enable or disable use of the selected input method (@code{toggle-input-method}). |
| 487 | |
| 488 | @item C-x @key{RET} C-\ @var{method} @key{RET} |
| 489 | Select a new input method for the current buffer (@code{set-input-method}). |
| 490 | |
| 491 | @item C-h I @var{method} @key{RET} |
| 492 | @itemx C-h C-\ @var{method} @key{RET} |
| 493 | @findex describe-input-method |
| 494 | @kindex C-h I |
| 495 | @kindex C-h C-\ |
| 496 | Describe the input method @var{method} (@code{describe-input-method}). |
| 497 | By default, it describes the current input method (if any). This |
| 498 | description should give you the full details of how to use any |
| 499 | particular input method. |
| 500 | |
| 501 | @item M-x list-input-methods |
| 502 | Display a list of all the supported input methods. |
| 503 | @end table |
| 504 | |
| 505 | @findex set-input-method |
| 506 | @vindex current-input-method |
| 507 | @kindex C-x RET C-\ |
| 508 | To choose an input method for the current buffer, use @kbd{C-x |
| 509 | @key{RET} C-\} (@code{set-input-method}). This command reads the |
| 510 | input method name from the minibuffer; the name normally starts with the |
| 511 | language environment that it is meant to be used with. The variable |
| 512 | @code{current-input-method} records which input method is selected. |
| 513 | |
| 514 | @findex toggle-input-method |
| 515 | @kindex C-\ |
| 516 | Input methods use various sequences of @acronym{ASCII} characters to |
| 517 | stand for non-@acronym{ASCII} characters. Sometimes it is useful to |
| 518 | turn off the input method temporarily. To do this, type @kbd{C-\} |
| 519 | (@code{toggle-input-method}). To reenable the input method, type |
| 520 | @kbd{C-\} again. |
| 521 | |
| 522 | If you type @kbd{C-\} and you have not yet selected an input method, |
| 523 | it prompts you to specify one. This has the same effect as using |
| 524 | @kbd{C-x @key{RET} C-\} to specify an input method. |
| 525 | |
| 526 | When invoked with a numeric argument, as in @kbd{C-u C-\}, |
| 527 | @code{toggle-input-method} always prompts you for an input method, |
| 528 | suggesting the most recently selected one as the default. |
| 529 | |
| 530 | @vindex default-input-method |
| 531 | Selecting a language environment specifies a default input method for |
| 532 | use in various buffers. When you have a default input method, you can |
| 533 | select it in the current buffer by typing @kbd{C-\}. The variable |
| 534 | @code{default-input-method} specifies the default input method |
| 535 | (@code{nil} means there is none). |
| 536 | |
| 537 | In some language environments, which support several different input |
| 538 | methods, you might want to use an input method different from the |
| 539 | default chosen by @code{set-language-environment}. You can instruct |
| 540 | Emacs to select a different default input method for a certain |
| 541 | language environment, if you wish, by using |
| 542 | @code{set-language-environment-hook} (@pxref{Language Environments, |
| 543 | set-language-environment-hook}). For example: |
| 544 | |
| 545 | @lisp |
| 546 | (defun my-chinese-setup () |
| 547 | "Set up my private Chinese environment." |
| 548 | (if (equal current-language-environment "Chinese-GB") |
| 549 | (setq default-input-method "chinese-tonepy"))) |
| 550 | (add-hook 'set-language-environment-hook 'my-chinese-setup) |
| 551 | @end lisp |
| 552 | |
| 553 | @noindent |
| 554 | This sets the default input method to be @code{chinese-tonepy} |
| 555 | whenever you choose a Chinese-GB language environment. |
| 556 | |
| 557 | You can instruct Emacs to activate a certain input method |
| 558 | automatically. For example: |
| 559 | |
| 560 | @lisp |
| 561 | (add-hook 'text-mode-hook |
| 562 | (lambda () (set-input-method "german-prefix"))) |
| 563 | @end lisp |
| 564 | |
| 565 | @noindent |
| 566 | This automatically activates the input method ``german-prefix'' in |
| 567 | Text mode. |
| 568 | |
| 569 | @findex quail-set-keyboard-layout |
| 570 | Some input methods for alphabetic scripts work by (in effect) |
| 571 | remapping the keyboard to emulate various keyboard layouts commonly used |
| 572 | for those scripts. How to do this remapping properly depends on your |
| 573 | actual keyboard layout. To specify which layout your keyboard has, use |
| 574 | the command @kbd{M-x quail-set-keyboard-layout}. |
| 575 | |
| 576 | @findex quail-show-key |
| 577 | You can use the command @kbd{M-x quail-show-key} to show what key (or |
| 578 | key sequence) to type in order to input the character following point, |
| 579 | using the selected keyboard layout. The command @kbd{C-u C-x =} also |
| 580 | shows that information, in addition to other information about the |
| 581 | character. |
| 582 | |
| 583 | @findex list-input-methods |
| 584 | @kbd{M-x list-input-methods} displays a list of all the supported |
| 585 | input methods. The list gives information about each input method, |
| 586 | including the string that stands for it in the mode line. |
| 587 | |
| 588 | @node Coding Systems |
| 589 | @section Coding Systems |
| 590 | @cindex coding systems |
| 591 | |
| 592 | Users of various languages have established many more-or-less standard |
| 593 | coding systems for representing them. Emacs does not use these coding |
| 594 | systems internally; instead, it converts from various coding systems to |
| 595 | its own system when reading data, and converts the internal coding |
| 596 | system to other coding systems when writing data. Conversion is |
| 597 | possible in reading or writing files, in sending or receiving from the |
| 598 | terminal, and in exchanging data with subprocesses. |
| 599 | |
| 600 | Emacs assigns a name to each coding system. Most coding systems are |
| 601 | used for one language, and the name of the coding system starts with |
| 602 | the language name. Some coding systems are used for several |
| 603 | languages; their names usually start with @samp{iso}. There are also |
| 604 | special coding systems, such as @code{no-conversion}, @code{raw-text}, |
| 605 | and @code{emacs-internal}. |
| 606 | |
| 607 | @cindex international files from DOS/Windows systems |
| 608 | A special class of coding systems, collectively known as |
| 609 | @dfn{codepages}, is designed to support text encoded by MS-Windows and |
| 610 | MS-DOS software. The names of these coding systems are |
| 611 | @code{cp@var{nnnn}}, where @var{nnnn} is a 3- or 4-digit number of the |
| 612 | codepage. You can use these encodings just like any other coding |
| 613 | system; for example, to visit a file encoded in codepage 850, type |
| 614 | @kbd{C-x @key{RET} c cp850 @key{RET} C-x C-f @var{filename} |
| 615 | @key{RET}}. |
| 616 | |
| 617 | In addition to converting various representations of non-@acronym{ASCII} |
| 618 | characters, a coding system can perform end-of-line conversion. Emacs |
| 619 | handles three different conventions for how to separate lines in a file: |
| 620 | newline (``unix''), carriage-return linefeed (``dos''), and just |
| 621 | carriage-return (``mac''). |
| 622 | |
| 623 | @table @kbd |
| 624 | @item C-h C @var{coding} @key{RET} |
| 625 | Describe coding system @var{coding} (@code{describe-coding-system}). |
| 626 | |
| 627 | @item C-h C @key{RET} |
| 628 | Describe the coding systems currently in use. |
| 629 | |
| 630 | @item M-x list-coding-systems |
| 631 | Display a list of all the supported coding systems. |
| 632 | @end table |
| 633 | |
| 634 | @kindex C-h C |
| 635 | @findex describe-coding-system |
| 636 | The command @kbd{C-h C} (@code{describe-coding-system}) displays |
| 637 | information about particular coding systems, including the end-of-line |
| 638 | conversion specified by those coding systems. You can specify a coding |
| 639 | system name as the argument; alternatively, with an empty argument, it |
| 640 | describes the coding systems currently selected for various purposes, |
| 641 | both in the current buffer and as the defaults, and the priority list |
| 642 | for recognizing coding systems (@pxref{Recognize Coding}). |
| 643 | |
| 644 | @findex list-coding-systems |
| 645 | To display a list of all the supported coding systems, type @kbd{M-x |
| 646 | list-coding-systems}. The list gives information about each coding |
| 647 | system, including the letter that stands for it in the mode line |
| 648 | (@pxref{Mode Line}). |
| 649 | |
| 650 | @cindex end-of-line conversion |
| 651 | @cindex line endings |
| 652 | @cindex MS-DOS end-of-line conversion |
| 653 | @cindex Macintosh end-of-line conversion |
| 654 | Each of the coding systems that appear in this list---except for |
| 655 | @code{no-conversion}, which means no conversion of any kind---specifies |
| 656 | how and whether to convert printing characters, but leaves the choice of |
| 657 | end-of-line conversion to be decided based on the contents of each file. |
| 658 | For example, if the file appears to use the sequence carriage-return |
| 659 | linefeed to separate lines, DOS end-of-line conversion will be used. |
| 660 | |
| 661 | Each of the listed coding systems has three variants, which specify |
| 662 | exactly what to do for end-of-line conversion: |
| 663 | |
| 664 | @table @code |
| 665 | @item @dots{}-unix |
| 666 | Don't do any end-of-line conversion; assume the file uses |
| 667 | newline to separate lines. (This is the convention normally used |
| 668 | on Unix and GNU systems, and Mac OS X.) |
| 669 | |
| 670 | @item @dots{}-dos |
| 671 | Assume the file uses carriage-return linefeed to separate lines, and do |
| 672 | the appropriate conversion. (This is the convention normally used on |
| 673 | Microsoft systems.@footnote{It is also specified for MIME @samp{text/*} |
| 674 | bodies and in other network transport contexts. It is different |
| 675 | from the SGML reference syntax record-start/record-end format, which |
| 676 | Emacs doesn't support directly.}) |
| 677 | |
| 678 | @item @dots{}-mac |
| 679 | Assume the file uses carriage-return to separate lines, and do the |
| 680 | appropriate conversion. (This was the convention used on the |
| 681 | Macintosh system prior to OS X.) |
| 682 | @end table |
| 683 | |
| 684 | These variant coding systems are omitted from the |
| 685 | @code{list-coding-systems} display for brevity, since they are entirely |
| 686 | predictable. For example, the coding system @code{iso-latin-1} has |
| 687 | variants @code{iso-latin-1-unix}, @code{iso-latin-1-dos} and |
| 688 | @code{iso-latin-1-mac}. |
| 689 | |
| 690 | @cindex @code{undecided}, coding system |
| 691 | The coding systems @code{unix}, @code{dos}, and @code{mac} are |
| 692 | aliases for @code{undecided-unix}, @code{undecided-dos}, and |
| 693 | @code{undecided-mac}, respectively. These coding systems specify only |
| 694 | the end-of-line conversion, and leave the character code conversion to |
| 695 | be deduced from the text itself. |
| 696 | |
| 697 | @cindex @code{raw-text}, coding system |
| 698 | The coding system @code{raw-text} is good for a file which is mainly |
| 699 | @acronym{ASCII} text, but may contain byte values above 127 that are |
| 700 | not meant to encode non-@acronym{ASCII} characters. With |
| 701 | @code{raw-text}, Emacs copies those byte values unchanged, and sets |
| 702 | @code{enable-multibyte-characters} to @code{nil} in the current buffer |
| 703 | so that they will be interpreted properly. @code{raw-text} handles |
| 704 | end-of-line conversion in the usual way, based on the data |
| 705 | encountered, and has the usual three variants to specify the kind of |
| 706 | end-of-line conversion to use. |
| 707 | |
| 708 | @cindex @code{no-conversion}, coding system |
| 709 | In contrast, the coding system @code{no-conversion} specifies no |
| 710 | character code conversion at all---none for non-@acronym{ASCII} byte values and |
| 711 | none for end of line. This is useful for reading or writing binary |
| 712 | files, tar files, and other files that must be examined verbatim. It, |
| 713 | too, sets @code{enable-multibyte-characters} to @code{nil}. |
| 714 | |
| 715 | The easiest way to edit a file with no conversion of any kind is with |
| 716 | the @kbd{M-x find-file-literally} command. This uses |
| 717 | @code{no-conversion}, and also suppresses other Emacs features that |
| 718 | might convert the file contents before you see them. @xref{Visiting}. |
| 719 | |
| 720 | @cindex @code{emacs-internal}, coding system |
| 721 | The coding system @code{emacs-internal} (or @code{utf-8-emacs}, |
| 722 | which is equivalent) means that the file contains non-@acronym{ASCII} |
| 723 | characters stored with the internal Emacs encoding. This coding |
| 724 | system handles end-of-line conversion based on the data encountered, |
| 725 | and has the usual three variants to specify the kind of end-of-line |
| 726 | conversion. |
| 727 | |
| 728 | @node Recognize Coding |
| 729 | @section Recognizing Coding Systems |
| 730 | |
| 731 | Whenever Emacs reads a given piece of text, it tries to recognize |
| 732 | which coding system to use. This applies to files being read, output |
| 733 | from subprocesses, text from X selections, etc. Emacs can select the |
| 734 | right coding system automatically most of the time---once you have |
| 735 | specified your preferences. |
| 736 | |
| 737 | Some coding systems can be recognized or distinguished by which byte |
| 738 | sequences appear in the data. However, there are coding systems that |
| 739 | cannot be distinguished, not even potentially. For example, there is no |
| 740 | way to distinguish between Latin-1 and Latin-2; they use the same byte |
| 741 | values with different meanings. |
| 742 | |
| 743 | Emacs handles this situation by means of a priority list of coding |
| 744 | systems. Whenever Emacs reads a file, if you do not specify the coding |
| 745 | system to use, Emacs checks the data against each coding system, |
| 746 | starting with the first in priority and working down the list, until it |
| 747 | finds a coding system that fits the data. Then it converts the file |
| 748 | contents assuming that they are represented in this coding system. |
| 749 | |
| 750 | The priority list of coding systems depends on the selected language |
| 751 | environment (@pxref{Language Environments}). For example, if you use |
| 752 | French, you probably want Emacs to prefer Latin-1 to Latin-2; if you use |
| 753 | Czech, you probably want Latin-2 to be preferred. This is one of the |
| 754 | reasons to specify a language environment. |
| 755 | |
| 756 | @findex prefer-coding-system |
| 757 | However, you can alter the coding system priority list in detail |
| 758 | with the command @kbd{M-x prefer-coding-system}. This command reads |
| 759 | the name of a coding system from the minibuffer, and adds it to the |
| 760 | front of the priority list, so that it is preferred to all others. If |
| 761 | you use this command several times, each use adds one element to the |
| 762 | front of the priority list. |
| 763 | |
| 764 | If you use a coding system that specifies the end-of-line conversion |
| 765 | type, such as @code{iso-8859-1-dos}, what this means is that Emacs |
| 766 | should attempt to recognize @code{iso-8859-1} with priority, and should |
| 767 | use DOS end-of-line conversion when it does recognize @code{iso-8859-1}. |
| 768 | |
| 769 | @vindex file-coding-system-alist |
| 770 | Sometimes a file name indicates which coding system to use for the |
| 771 | file. The variable @code{file-coding-system-alist} specifies this |
| 772 | correspondence. There is a special function |
| 773 | @code{modify-coding-system-alist} for adding elements to this list. For |
| 774 | example, to read and write all @samp{.txt} files using the coding system |
| 775 | @code{chinese-iso-8bit}, you can execute this Lisp expression: |
| 776 | |
| 777 | @smallexample |
| 778 | (modify-coding-system-alist 'file "\\.txt\\'" 'chinese-iso-8bit) |
| 779 | @end smallexample |
| 780 | |
| 781 | @noindent |
| 782 | The first argument should be @code{file}, the second argument should be |
| 783 | a regular expression that determines which files this applies to, and |
| 784 | the third argument says which coding system to use for these files. |
| 785 | |
| 786 | @vindex inhibit-eol-conversion |
| 787 | @cindex DOS-style end-of-line display |
| 788 | Emacs recognizes which kind of end-of-line conversion to use based on |
| 789 | the contents of the file: if it sees only carriage-returns, or only |
| 790 | carriage-return linefeed sequences, then it chooses the end-of-line |
| 791 | conversion accordingly. You can inhibit the automatic use of |
| 792 | end-of-line conversion by setting the variable @code{inhibit-eol-conversion} |
| 793 | to non-@code{nil}. If you do that, DOS-style files will be displayed |
| 794 | with the @samp{^M} characters visible in the buffer; some people |
| 795 | prefer this to the more subtle @samp{(DOS)} end-of-line type |
| 796 | indication near the left edge of the mode line (@pxref{Mode Line, |
| 797 | eol-mnemonic}). |
| 798 | |
| 799 | @vindex inhibit-iso-escape-detection |
| 800 | @cindex escape sequences in files |
| 801 | By default, the automatic detection of coding system is sensitive to |
| 802 | escape sequences. If Emacs sees a sequence of characters that begin |
| 803 | with an escape character, and the sequence is valid as an ISO-2022 |
| 804 | code, that tells Emacs to use one of the ISO-2022 encodings to decode |
| 805 | the file. |
| 806 | |
| 807 | However, there may be cases that you want to read escape sequences |
| 808 | in a file as is. In such a case, you can set the variable |
| 809 | @code{inhibit-iso-escape-detection} to non-@code{nil}. Then the code |
| 810 | detection ignores any escape sequences, and never uses an ISO-2022 |
| 811 | encoding. The result is that all escape sequences become visible in |
| 812 | the buffer. |
| 813 | |
| 814 | The default value of @code{inhibit-iso-escape-detection} is |
| 815 | @code{nil}. We recommend that you not change it permanently, only for |
| 816 | one specific operation. That's because some Emacs Lisp source files |
| 817 | in the Emacs distribution contain non-@acronym{ASCII} characters encoded in the |
| 818 | coding system @code{iso-2022-7bit}, and they won't be |
| 819 | decoded correctly when you visit those files if you suppress the |
| 820 | escape sequence detection. |
| 821 | @c I count a grand total of 3 such files, so is the above really true? |
| 822 | |
| 823 | @vindex auto-coding-alist |
| 824 | @vindex auto-coding-regexp-alist |
| 825 | The variables @code{auto-coding-alist} and |
| 826 | @code{auto-coding-regexp-alist} are |
| 827 | the strongest way to specify the coding system for certain patterns of |
| 828 | file names, or for files containing certain patterns, respectively. |
| 829 | These variables even override @samp{-*-coding:-*-} tags in the file |
| 830 | itself (@pxref{Specify Coding}). For example, Emacs |
| 831 | uses @code{auto-coding-alist} for tar and archive files, to prevent it |
| 832 | from being confused by a @samp{-*-coding:-*-} tag in a member of the |
| 833 | archive and thinking it applies to the archive file as a whole. |
| 834 | @ignore |
| 835 | @c This describes old-style BABYL files, which are no longer relevant. |
| 836 | Likewise, Emacs uses @code{auto-coding-regexp-alist} to ensure that |
| 837 | RMAIL files, whose names in general don't match any particular |
| 838 | pattern, are decoded correctly. |
| 839 | @end ignore |
| 840 | |
| 841 | @vindex auto-coding-functions |
| 842 | Another way to specify a coding system is with the variable |
| 843 | @code{auto-coding-functions}. For example, one of the builtin |
| 844 | @code{auto-coding-functions} detects the encoding for XML files. |
| 845 | Unlike the previous two, this variable does not override any |
| 846 | @samp{-*-coding:-*-} tag. |
| 847 | |
| 848 | @node Specify Coding |
| 849 | @section Specifying a File's Coding System |
| 850 | |
| 851 | If Emacs recognizes the encoding of a file incorrectly, you can |
| 852 | reread the file using the correct coding system with @kbd{C-x |
| 853 | @key{RET} r} (@code{revert-buffer-with-coding-system}). This command |
| 854 | prompts for the coding system to use. To see what coding system Emacs |
| 855 | actually used to decode the file, look at the coding system mnemonic |
| 856 | letter near the left edge of the mode line (@pxref{Mode Line}), or |
| 857 | type @kbd{C-h C} (@code{describe-coding-system}). |
| 858 | |
| 859 | @vindex coding |
| 860 | You can specify the coding system for a particular file in the file |
| 861 | itself, using the @w{@samp{-*-@dots{}-*-}} construct at the beginning, |
| 862 | or a local variables list at the end (@pxref{File Variables}). You do |
| 863 | this by defining a value for the ``variable'' named @code{coding}. |
| 864 | Emacs does not really have a variable @code{coding}; instead of |
| 865 | setting a variable, this uses the specified coding system for the |
| 866 | file. For example, @samp{-*-mode: C; coding: latin-1;-*-} specifies |
| 867 | use of the Latin-1 coding system, as well as C mode. When you specify |
| 868 | the coding explicitly in the file, that overrides |
| 869 | @code{file-coding-system-alist}. |
| 870 | |
| 871 | @node Output Coding |
| 872 | @section Choosing Coding Systems for Output |
| 873 | |
| 874 | @vindex buffer-file-coding-system |
| 875 | Once Emacs has chosen a coding system for a buffer, it stores that |
| 876 | coding system in @code{buffer-file-coding-system}. That makes it the |
| 877 | default for operations that write from this buffer into a file, such |
| 878 | as @code{save-buffer} and @code{write-region}. You can specify a |
| 879 | different coding system for further file output from the buffer using |
| 880 | @code{set-buffer-file-coding-system} (@pxref{Text Coding}). |
| 881 | |
| 882 | You can insert any character Emacs supports into any Emacs buffer, |
| 883 | but most coding systems can only handle a subset of these characters. |
| 884 | Therefore, it's possible that the characters you insert cannot be |
| 885 | encoded with the coding system that will be used to save the buffer. |
| 886 | For example, you could visit a text file in Polish, encoded in |
| 887 | @code{iso-8859-2}, and add some Russian words to it. When you save |
| 888 | that buffer, Emacs cannot use the current value of |
| 889 | @code{buffer-file-coding-system}, because the characters you added |
| 890 | cannot be encoded by that coding system. |
| 891 | |
| 892 | When that happens, Emacs tries the most-preferred coding system (set |
| 893 | by @kbd{M-x prefer-coding-system} or @kbd{M-x |
| 894 | set-language-environment}). If that coding system can safely encode |
| 895 | all of the characters in the buffer, Emacs uses it, and stores its |
| 896 | value in @code{buffer-file-coding-system}. Otherwise, Emacs displays |
| 897 | a list of coding systems suitable for encoding the buffer's contents, |
| 898 | and asks you to choose one of those coding systems. |
| 899 | |
| 900 | If you insert the unsuitable characters in a mail message, Emacs |
| 901 | behaves a bit differently. It additionally checks whether the |
| 902 | @c What determines this? |
| 903 | most-preferred coding system is recommended for use in MIME messages; |
| 904 | if not, it informs you of this fact and prompts you for another coding |
| 905 | system. This is so you won't inadvertently send a message encoded in |
| 906 | a way that your recipient's mail software will have difficulty |
| 907 | decoding. (You can still use an unsuitable coding system if you enter |
| 908 | its name at the prompt.) |
| 909 | |
| 910 | @c It seems that select-message-coding-system does this. |
| 911 | @c Both sendmail.el and smptmail.el call it; i.e., smtpmail.el still |
| 912 | @c obeys sendmail-coding-system. |
| 913 | @vindex sendmail-coding-system |
| 914 | When you send a mail message (@pxref{Sending Mail}), |
| 915 | Emacs has four different ways to determine the coding system to use |
| 916 | for encoding the message text. It tries the buffer's own value of |
| 917 | @code{buffer-file-coding-system}, if that is non-@code{nil}. |
| 918 | Otherwise, it uses the value of @code{sendmail-coding-system}, if that |
| 919 | is non-@code{nil}. The third way is to use the default coding system |
| 920 | for new files, which is controlled by your choice of language |
| 921 | @c i.e., default-sendmail-coding-system |
| 922 | environment, if that is non-@code{nil}. If all of these three values |
| 923 | are @code{nil}, Emacs encodes outgoing mail using the Latin-1 coding |
| 924 | system. |
| 925 | @c FIXME? Where does the Latin-1 default come in? |
| 926 | |
| 927 | @node Text Coding |
| 928 | @section Specifying a Coding System for File Text |
| 929 | |
| 930 | In cases where Emacs does not automatically choose the right coding |
| 931 | system for a file's contents, you can use these commands to specify |
| 932 | one: |
| 933 | |
| 934 | @table @kbd |
| 935 | @item C-x @key{RET} f @var{coding} @key{RET} |
| 936 | Use coding system @var{coding} to save or revisit the file in |
| 937 | the current buffer (@code{set-buffer-file-coding-system}). |
| 938 | |
| 939 | @item C-x @key{RET} c @var{coding} @key{RET} |
| 940 | Specify coding system @var{coding} for the immediately following |
| 941 | command (@code{universal-coding-system-argument}). |
| 942 | |
| 943 | @item C-x @key{RET} r @var{coding} @key{RET} |
| 944 | Revisit the current file using the coding system @var{coding} |
| 945 | (@code{revert-buffer-with-coding-system}). |
| 946 | |
| 947 | @item M-x recode-region @key{RET} @var{right} @key{RET} @var{wrong} @key{RET} |
| 948 | Convert a region that was decoded using coding system @var{wrong}, |
| 949 | decoding it using coding system @var{right} instead. |
| 950 | @end table |
| 951 | |
| 952 | @kindex C-x RET f |
| 953 | @findex set-buffer-file-coding-system |
| 954 | The command @kbd{C-x @key{RET} f} |
| 955 | (@code{set-buffer-file-coding-system}) sets the file coding system for |
| 956 | the current buffer (i.e., the coding system to use when saving or |
| 957 | reverting the file). You specify which coding system using the |
| 958 | minibuffer. You can also invoke this command by clicking with |
| 959 | @kbd{Mouse-3} on the coding system indicator in the mode line |
| 960 | (@pxref{Mode Line}). |
| 961 | |
| 962 | If you specify a coding system that cannot handle all the characters |
| 963 | in the buffer, Emacs will warn you about the troublesome characters, |
| 964 | and ask you to choose another coding system, when you try to save the |
| 965 | buffer (@pxref{Output Coding}). |
| 966 | |
| 967 | @cindex specify end-of-line conversion |
| 968 | You can also use this command to specify the end-of-line conversion |
| 969 | (@pxref{Coding Systems, end-of-line conversion}) for encoding the |
| 970 | current buffer. For example, @kbd{C-x @key{RET} f dos @key{RET}} will |
| 971 | cause Emacs to save the current buffer's text with DOS-style |
| 972 | carriage-return linefeed line endings. |
| 973 | |
| 974 | @kindex C-x RET c |
| 975 | @findex universal-coding-system-argument |
| 976 | Another way to specify the coding system for a file is when you visit |
| 977 | the file. First use the command @kbd{C-x @key{RET} c} |
| 978 | (@code{universal-coding-system-argument}); this command uses the |
| 979 | minibuffer to read a coding system name. After you exit the minibuffer, |
| 980 | the specified coding system is used for @emph{the immediately following |
| 981 | command}. |
| 982 | |
| 983 | So if the immediately following command is @kbd{C-x C-f}, for example, |
| 984 | it reads the file using that coding system (and records the coding |
| 985 | system for when you later save the file). Or if the immediately following |
| 986 | command is @kbd{C-x C-w}, it writes the file using that coding system. |
| 987 | When you specify the coding system for saving in this way, instead |
| 988 | of with @kbd{C-x @key{RET} f}, there is no warning if the buffer |
| 989 | contains characters that the coding system cannot handle. |
| 990 | |
| 991 | Other file commands affected by a specified coding system include |
| 992 | @kbd{C-x i} and @kbd{C-x C-v}, as well as the other-window variants |
| 993 | of @kbd{C-x C-f}. @kbd{C-x @key{RET} c} also affects commands that |
| 994 | start subprocesses, including @kbd{M-x shell} (@pxref{Shell}). If the |
| 995 | immediately following command does not use the coding system, then |
| 996 | @kbd{C-x @key{RET} c} ultimately has no effect. |
| 997 | |
| 998 | An easy way to visit a file with no conversion is with the @kbd{M-x |
| 999 | find-file-literally} command. @xref{Visiting}. |
| 1000 | |
| 1001 | The default value of the variable @code{buffer-file-coding-system} |
| 1002 | specifies the choice of coding system to use when you create a new file. |
| 1003 | It applies when you find a new file, and when you create a buffer and |
| 1004 | then save it in a file. Selecting a language environment typically sets |
| 1005 | this variable to a good choice of default coding system for that language |
| 1006 | environment. |
| 1007 | |
| 1008 | @kindex C-x RET r |
| 1009 | @findex revert-buffer-with-coding-system |
| 1010 | If you visit a file with a wrong coding system, you can correct this |
| 1011 | with @kbd{C-x @key{RET} r} (@code{revert-buffer-with-coding-system}). |
| 1012 | This visits the current file again, using a coding system you specify. |
| 1013 | |
| 1014 | @findex recode-region |
| 1015 | If a piece of text has already been inserted into a buffer using the |
| 1016 | wrong coding system, you can redo the decoding of it using @kbd{M-x |
| 1017 | recode-region}. This prompts you for the proper coding system, then |
| 1018 | for the wrong coding system that was actually used, and does the |
| 1019 | conversion. It first encodes the region using the wrong coding system, |
| 1020 | then decodes it again using the proper coding system. |
| 1021 | |
| 1022 | @node Communication Coding |
| 1023 | @section Coding Systems for Interprocess Communication |
| 1024 | |
| 1025 | This section explains how to specify coding systems for use |
| 1026 | in communication with other processes. |
| 1027 | |
| 1028 | @table @kbd |
| 1029 | @item C-x @key{RET} x @var{coding} @key{RET} |
| 1030 | Use coding system @var{coding} for transferring selections to and from |
| 1031 | other graphical applications (@code{set-selection-coding-system}). |
| 1032 | |
| 1033 | @item C-x @key{RET} X @var{coding} @key{RET} |
| 1034 | Use coding system @var{coding} for transferring @emph{one} |
| 1035 | selection---the next one---to or from another graphical application |
| 1036 | (@code{set-next-selection-coding-system}). |
| 1037 | |
| 1038 | @item C-x @key{RET} p @var{input-coding} @key{RET} @var{output-coding} @key{RET} |
| 1039 | Use coding systems @var{input-coding} and @var{output-coding} for |
| 1040 | subprocess input and output in the current buffer |
| 1041 | (@code{set-buffer-process-coding-system}). |
| 1042 | @end table |
| 1043 | |
| 1044 | @kindex C-x RET x |
| 1045 | @kindex C-x RET X |
| 1046 | @findex set-selection-coding-system |
| 1047 | @findex set-next-selection-coding-system |
| 1048 | The command @kbd{C-x @key{RET} x} (@code{set-selection-coding-system}) |
| 1049 | specifies the coding system for sending selected text to other windowing |
| 1050 | applications, and for receiving the text of selections made in other |
| 1051 | applications. This command applies to all subsequent selections, until |
| 1052 | you override it by using the command again. The command @kbd{C-x |
| 1053 | @key{RET} X} (@code{set-next-selection-coding-system}) specifies the |
| 1054 | coding system for the next selection made in Emacs or read by Emacs. |
| 1055 | |
| 1056 | @vindex x-select-request-type |
| 1057 | The variable @code{x-select-request-type} specifies the data type to |
| 1058 | request from the X Window System for receiving text selections from |
| 1059 | other applications. If the value is @code{nil} (the default), Emacs |
| 1060 | tries @code{UTF8_STRING} and @code{COMPOUND_TEXT}, in this order, and |
| 1061 | uses various heuristics to choose the more appropriate of the two |
| 1062 | results; if none of these succeed, Emacs falls back on @code{STRING}. |
| 1063 | If the value of @code{x-select-request-type} is one of the symbols |
| 1064 | @code{COMPOUND_TEXT}, @code{UTF8_STRING}, @code{STRING}, or |
| 1065 | @code{TEXT}, Emacs uses only that request type. If the value is a |
| 1066 | list of some of these symbols, Emacs tries only the request types in |
| 1067 | the list, in order, until one of them succeeds, or until the list is |
| 1068 | exhausted. |
| 1069 | |
| 1070 | @kindex C-x RET p |
| 1071 | @findex set-buffer-process-coding-system |
| 1072 | The command @kbd{C-x @key{RET} p} (@code{set-buffer-process-coding-system}) |
| 1073 | specifies the coding system for input and output to a subprocess. This |
| 1074 | command applies to the current buffer; normally, each subprocess has its |
| 1075 | own buffer, and thus you can use this command to specify translation to |
| 1076 | and from a particular subprocess by giving the command in the |
| 1077 | corresponding buffer. |
| 1078 | |
| 1079 | You can also use @kbd{C-x @key{RET} c} |
| 1080 | (@code{universal-coding-system-argument}) just before the command that |
| 1081 | runs or starts a subprocess, to specify the coding system for |
| 1082 | communicating with that subprocess. @xref{Text Coding}. |
| 1083 | |
| 1084 | The default for translation of process input and output depends on the |
| 1085 | current language environment. |
| 1086 | |
| 1087 | @vindex locale-coding-system |
| 1088 | @cindex decoding non-@acronym{ASCII} keyboard input on X |
| 1089 | The variable @code{locale-coding-system} specifies a coding system |
| 1090 | to use when encoding and decoding system strings such as system error |
| 1091 | messages and @code{format-time-string} formats and time stamps. That |
| 1092 | coding system is also used for decoding non-@acronym{ASCII} keyboard |
| 1093 | input on the X Window System. You should choose a coding system that is compatible |
| 1094 | with the underlying system's text representation, which is normally |
| 1095 | specified by one of the environment variables @env{LC_ALL}, |
| 1096 | @env{LC_CTYPE}, and @env{LANG}. (The first one, in the order |
| 1097 | specified above, whose value is nonempty is the one that determines |
| 1098 | the text representation.) |
| 1099 | |
| 1100 | @node File Name Coding |
| 1101 | @section Coding Systems for File Names |
| 1102 | |
| 1103 | @table @kbd |
| 1104 | @item C-x @key{RET} F @var{coding} @key{RET} |
| 1105 | Use coding system @var{coding} for encoding and decoding file |
| 1106 | names (@code{set-file-name-coding-system}). |
| 1107 | @end table |
| 1108 | |
| 1109 | @findex set-file-name-coding-system |
| 1110 | @kindex C-x @key{RET} F |
| 1111 | @cindex file names with non-@acronym{ASCII} characters |
| 1112 | The command @kbd{C-x @key{RET} F} (@code{set-file-name-coding-system}) |
| 1113 | specifies a coding system to use for encoding file @emph{names}. It |
| 1114 | has no effect on reading and writing the @emph{contents} of files. |
| 1115 | |
| 1116 | @vindex file-name-coding-system |
| 1117 | In fact, all this command does is set the value of the variable |
| 1118 | @code{file-name-coding-system}. If you set the variable to a coding |
| 1119 | system name (as a Lisp symbol or a string), Emacs encodes file names |
| 1120 | using that coding system for all file operations. This makes it |
| 1121 | possible to use non-@acronym{ASCII} characters in file names---or, at |
| 1122 | least, those non-@acronym{ASCII} characters that the specified coding |
| 1123 | system can encode. |
| 1124 | |
| 1125 | If @code{file-name-coding-system} is @code{nil}, Emacs uses a |
| 1126 | default coding system determined by the selected language environment, |
| 1127 | and stored in the @code{default-file-name-coding-system} variable. |
| 1128 | @c FIXME? Is this correct? What is the "default language environment"? |
| 1129 | In the default language environment, non-@acronym{ASCII} characters in |
| 1130 | file names are not encoded specially; they appear in the file system |
| 1131 | using the internal Emacs representation. |
| 1132 | |
| 1133 | @cindex file-name encoding, MS-Windows |
| 1134 | @vindex w32-unicode-filenames |
| 1135 | When Emacs runs on MS-Windows versions that are descendants of the |
| 1136 | NT family (Windows 2000, XP, Vista, Windows 7, and Windows 8), the |
| 1137 | value of @code{file-name-coding-system} is largely ignored, as Emacs |
| 1138 | by default uses APIs that allow to pass Unicode file names directly. |
| 1139 | By contrast, on Windows 9X, file names are encoded using |
| 1140 | @code{file-name-coding-system}, which should be set to the codepage |
| 1141 | (@pxref{Coding Systems, codepage}) pertinent for the current system |
| 1142 | locale. The value of the variable @code{w32-unicode-filenames} |
| 1143 | controls whether Emacs uses the Unicode APIs when it calls OS |
| 1144 | functions that accept file names. This variable is set by the startup |
| 1145 | code to @code{nil} on Windows 9X, and to @code{t} on newer versions of |
| 1146 | MS-Windows. |
| 1147 | |
| 1148 | @strong{Warning:} if you change @code{file-name-coding-system} (or the |
| 1149 | language environment) in the middle of an Emacs session, problems can |
| 1150 | result if you have already visited files whose names were encoded using |
| 1151 | the earlier coding system and cannot be encoded (or are encoded |
| 1152 | differently) under the new coding system. If you try to save one of |
| 1153 | these buffers under the visited file name, saving may use the wrong file |
| 1154 | name, or it may encounter an error. If such a problem happens, use @kbd{C-x |
| 1155 | C-w} to specify a new file name for that buffer. |
| 1156 | |
| 1157 | @findex recode-file-name |
| 1158 | If a mistake occurs when encoding a file name, use the command |
| 1159 | @kbd{M-x recode-file-name} to change the file name's coding |
| 1160 | system. This prompts for an existing file name, its old coding |
| 1161 | system, and the coding system to which you wish to convert. |
| 1162 | |
| 1163 | @node Terminal Coding |
| 1164 | @section Coding Systems for Terminal I/O |
| 1165 | |
| 1166 | @table @kbd |
| 1167 | @item C-x @key{RET} t @var{coding} @key{RET} |
| 1168 | Use coding system @var{coding} for terminal output |
| 1169 | (@code{set-terminal-coding-system}). |
| 1170 | |
| 1171 | @item C-x @key{RET} k @var{coding} @key{RET} |
| 1172 | Use coding system @var{coding} for keyboard input |
| 1173 | (@code{set-keyboard-coding-system}). |
| 1174 | @end table |
| 1175 | |
| 1176 | @kindex C-x RET t |
| 1177 | @findex set-terminal-coding-system |
| 1178 | The command @kbd{C-x @key{RET} t} (@code{set-terminal-coding-system}) |
| 1179 | specifies the coding system for terminal output. If you specify a |
| 1180 | character code for terminal output, all characters output to the |
| 1181 | terminal are translated into that coding system. |
| 1182 | |
| 1183 | This feature is useful for certain character-only terminals built to |
| 1184 | support specific languages or character sets---for example, European |
| 1185 | terminals that support one of the ISO Latin character sets. You need to |
| 1186 | specify the terminal coding system when using multibyte text, so that |
| 1187 | Emacs knows which characters the terminal can actually handle. |
| 1188 | |
| 1189 | By default, output to the terminal is not translated at all, unless |
| 1190 | Emacs can deduce the proper coding system from your terminal type or |
| 1191 | your locale specification (@pxref{Language Environments}). |
| 1192 | |
| 1193 | @kindex C-x RET k |
| 1194 | @findex set-keyboard-coding-system |
| 1195 | @vindex keyboard-coding-system |
| 1196 | The command @kbd{C-x @key{RET} k} (@code{set-keyboard-coding-system}), |
| 1197 | or the variable @code{keyboard-coding-system}, specifies the coding |
| 1198 | system for keyboard input. Character-code translation of keyboard |
| 1199 | input is useful for terminals with keys that send non-@acronym{ASCII} |
| 1200 | graphic characters---for example, some terminals designed for ISO |
| 1201 | Latin-1 or subsets of it. |
| 1202 | |
| 1203 | By default, keyboard input is translated based on your system locale |
| 1204 | setting. If your terminal does not really support the encoding |
| 1205 | implied by your locale (for example, if you find it inserts a |
| 1206 | non-@acronym{ASCII} character if you type @kbd{M-i}), you will need to set |
| 1207 | @code{keyboard-coding-system} to @code{nil} to turn off encoding. |
| 1208 | You can do this by putting |
| 1209 | |
| 1210 | @lisp |
| 1211 | (set-keyboard-coding-system nil) |
| 1212 | @end lisp |
| 1213 | |
| 1214 | @noindent |
| 1215 | in your init file. |
| 1216 | |
| 1217 | There is a similarity between using a coding system translation for |
| 1218 | keyboard input, and using an input method: both define sequences of |
| 1219 | keyboard input that translate into single characters. However, input |
| 1220 | methods are designed to be convenient for interactive use by humans, and |
| 1221 | the sequences that are translated are typically sequences of @acronym{ASCII} |
| 1222 | printing characters. Coding systems typically translate sequences of |
| 1223 | non-graphic characters. |
| 1224 | |
| 1225 | @node Fontsets |
| 1226 | @section Fontsets |
| 1227 | @cindex fontsets |
| 1228 | |
| 1229 | A font typically defines shapes for a single alphabet or script. |
| 1230 | Therefore, displaying the entire range of scripts that Emacs supports |
| 1231 | requires a collection of many fonts. In Emacs, such a collection is |
| 1232 | called a @dfn{fontset}. A fontset is defined by a list of font specifications, |
| 1233 | each assigned to handle a range of character codes, and may fall back |
| 1234 | on another fontset for characters that are not covered by the fonts |
| 1235 | it specifies. |
| 1236 | |
| 1237 | @cindex fonts for various scripts |
| 1238 | @cindex Intlfonts package, installation |
| 1239 | Each fontset has a name, like a font. However, while fonts are |
| 1240 | stored in the system and the available font names are defined by the |
| 1241 | system, fontsets are defined within Emacs itself. Once you have |
| 1242 | defined a fontset, you can use it within Emacs by specifying its name, |
| 1243 | anywhere that you could use a single font. Of course, Emacs fontsets |
| 1244 | can use only the fonts that the system supports. If some characters |
| 1245 | appear on the screen as empty boxes or hex codes, this means that the |
| 1246 | fontset in use for them has no font for those characters. In this |
| 1247 | case, or if the characters are shown, but not as well as you would |
| 1248 | like, you may need to install extra fonts. Your operating system may |
| 1249 | have optional fonts that you can install; or you can install the GNU |
| 1250 | Intlfonts package, which includes fonts for most supported |
| 1251 | scripts.@footnote{If you run Emacs on X, you may need to inform the X |
| 1252 | server about the location of the newly installed fonts with commands |
| 1253 | such as: |
| 1254 | @c FIXME? I feel like this may be out of date. |
| 1255 | @c E.g., the intlfonts tarfile is ~ 10 years old. |
| 1256 | |
| 1257 | @example |
| 1258 | xset fp+ /usr/local/share/emacs/fonts |
| 1259 | xset fp rehash |
| 1260 | @end example |
| 1261 | } |
| 1262 | |
| 1263 | Emacs creates three fontsets automatically: the @dfn{standard |
| 1264 | fontset}, the @dfn{startup fontset} and the @dfn{default fontset}. |
| 1265 | @c FIXME? The doc of *standard*-fontset-spec says: |
| 1266 | @c "You have the biggest chance to display international characters |
| 1267 | @c with correct glyphs by using the *standard* fontset." (my emphasis) |
| 1268 | @c See http://lists.gnu.org/archive/html/emacs-devel/2012-04/msg00430.html |
| 1269 | The default fontset is most likely to have fonts for a wide variety of |
| 1270 | non-@acronym{ASCII} characters, and is the default fallback for the |
| 1271 | other two fontsets, and if you set a default font rather than fontset. |
| 1272 | However, it does not specify font family names, so results can be |
| 1273 | somewhat random if you use it directly. You can specify use of a |
| 1274 | particular fontset by starting Emacs with the @samp{-fn} option. |
| 1275 | For example, |
| 1276 | |
| 1277 | @example |
| 1278 | emacs -fn fontset-standard |
| 1279 | @end example |
| 1280 | |
| 1281 | @noindent |
| 1282 | You can also specify a fontset with the @samp{Font} resource (@pxref{X |
| 1283 | Resources}). |
| 1284 | |
| 1285 | If no fontset is specified for use, then Emacs uses an |
| 1286 | @acronym{ASCII} font, with @samp{fontset-default} as a fallback for |
| 1287 | characters the font does not cover. The standard fontset is only used if |
| 1288 | explicitly requested, despite its name. |
| 1289 | |
| 1290 | A fontset does not necessarily specify a font for every character |
| 1291 | code. If a fontset specifies no font for a certain character, or if |
| 1292 | it specifies a font that does not exist on your system, then it cannot |
| 1293 | display that character properly. It will display that character as a |
| 1294 | hex code or thin space or an empty box instead. (@xref{Text Display, , |
| 1295 | glyphless characters}, for details.) |
| 1296 | |
| 1297 | @node Defining Fontsets |
| 1298 | @section Defining fontsets |
| 1299 | |
| 1300 | @vindex standard-fontset-spec |
| 1301 | @vindex w32-standard-fontset-spec |
| 1302 | @vindex ns-standard-fontset-spec |
| 1303 | @cindex standard fontset |
| 1304 | When running on X, Emacs creates a standard fontset automatically according to the value |
| 1305 | of @code{standard-fontset-spec}. This fontset's name is |
| 1306 | |
| 1307 | @example |
| 1308 | -*-fixed-medium-r-normal-*-16-*-*-*-*-*-fontset-standard |
| 1309 | @end example |
| 1310 | |
| 1311 | @noindent |
| 1312 | or just @samp{fontset-standard} for short. |
| 1313 | |
| 1314 | On GNUstep and Mac OS X, the standard fontset is created using the value of |
| 1315 | @code{ns-standard-fontset-spec}, and on MS Windows it is |
| 1316 | created using the value of @code{w32-standard-fontset-spec}. |
| 1317 | |
| 1318 | @c FIXME? How does one access these, or do anything with them? |
| 1319 | @c Does it matter? |
| 1320 | Bold, italic, and bold-italic variants of the standard fontset are |
| 1321 | created automatically. Their names have @samp{bold} instead of |
| 1322 | @samp{medium}, or @samp{i} instead of @samp{r}, or both. |
| 1323 | |
| 1324 | @cindex startup fontset |
| 1325 | Emacs generates a fontset automatically, based on any default |
| 1326 | @acronym{ASCII} font that you specify with the @samp{Font} resource or |
| 1327 | the @samp{-fn} argument, or the default font that Emacs found when it |
| 1328 | started. This is the @dfn{startup fontset} and its name is |
| 1329 | @code{fontset-startup}. It does this by replacing the |
| 1330 | @var{charset_registry} field with @samp{fontset}, and replacing |
| 1331 | @var{charset_encoding} field with @samp{startup}, then using the |
| 1332 | resulting string to specify a fontset. |
| 1333 | |
| 1334 | For instance, if you start Emacs with a font of this form, |
| 1335 | |
| 1336 | @c FIXME? I think this is a little misleading, because you cannot (?) |
| 1337 | @c actually specify a font with wildcards, it has to be a complete spec. |
| 1338 | @c Also, an X font specification of this form hasn't (?) been |
| 1339 | @c mentioned before now, and is somewhat obsolete these days. |
| 1340 | @c People are more likely to use a form like |
| 1341 | @c emacs -fn "DejaVu Sans Mono-12" |
| 1342 | @c How does any of this apply in that case? |
| 1343 | @example |
| 1344 | emacs -fn "*courier-medium-r-normal--14-140-*-iso8859-1" |
| 1345 | @end example |
| 1346 | |
| 1347 | @noindent |
| 1348 | Emacs generates the following fontset and uses it for the initial X |
| 1349 | window frame: |
| 1350 | |
| 1351 | @example |
| 1352 | -*-courier-medium-r-normal-*-14-140-*-*-*-*-fontset-startup |
| 1353 | @end example |
| 1354 | |
| 1355 | The startup fontset will use the font that you specify, or a variant |
| 1356 | with a different registry and encoding, for all the characters that |
| 1357 | are supported by that font, and fallback on @samp{fontset-default} for |
| 1358 | other characters. |
| 1359 | |
| 1360 | With the X resource @samp{Emacs.Font}, you can specify a fontset name |
| 1361 | just like an actual font name. But be careful not to specify a fontset |
| 1362 | name in a wildcard resource like @samp{Emacs*Font}---that wildcard |
| 1363 | specification matches various other resources, such as for menus, and |
| 1364 | @c FIXME is this still true? |
| 1365 | menus cannot handle fontsets. @xref{X Resources}. |
| 1366 | |
| 1367 | You can specify additional fontsets using X resources named |
| 1368 | @samp{Fontset-@var{n}}, where @var{n} is an integer starting from 0. |
| 1369 | The resource value should have this form: |
| 1370 | |
| 1371 | @smallexample |
| 1372 | @var{fontpattern}, @r{[}@var{charset}:@var{font}@r{]@dots{}} |
| 1373 | @end smallexample |
| 1374 | |
| 1375 | @noindent |
| 1376 | @var{fontpattern} should have the form of a standard X font name (see |
| 1377 | the previous fontset-startup example), except |
| 1378 | for the last two fields. They should have the form |
| 1379 | @samp{fontset-@var{alias}}. |
| 1380 | |
| 1381 | The fontset has two names, one long and one short. The long name is |
| 1382 | @var{fontpattern}. The short name is @samp{fontset-@var{alias}}. You |
| 1383 | can refer to the fontset by either name. |
| 1384 | |
| 1385 | The construct @samp{@var{charset}:@var{font}} specifies which font to |
| 1386 | use (in this fontset) for one particular character set. Here, |
| 1387 | @var{charset} is the name of a character set, and @var{font} is the |
| 1388 | font to use for that character set. You can use this construct any |
| 1389 | number of times in defining one fontset. |
| 1390 | |
| 1391 | For the other character sets, Emacs chooses a font based on |
| 1392 | @var{fontpattern}. It replaces @samp{fontset-@var{alias}} with values |
| 1393 | that describe the character set. For the @acronym{ASCII} character font, |
| 1394 | @samp{fontset-@var{alias}} is replaced with @samp{ISO8859-1}. |
| 1395 | |
| 1396 | In addition, when several consecutive fields are wildcards, Emacs |
| 1397 | collapses them into a single wildcard. This is to prevent use of |
| 1398 | auto-scaled fonts. Fonts made by scaling larger fonts are not usable |
| 1399 | for editing, and scaling a smaller font is not also useful, because it is |
| 1400 | better to use the smaller font in its own size, which is what Emacs |
| 1401 | does. |
| 1402 | |
| 1403 | Thus if @var{fontpattern} is this, |
| 1404 | |
| 1405 | @example |
| 1406 | -*-fixed-medium-r-normal-*-24-*-*-*-*-*-fontset-24 |
| 1407 | @end example |
| 1408 | |
| 1409 | @noindent |
| 1410 | the font specification for @acronym{ASCII} characters would be this: |
| 1411 | |
| 1412 | @example |
| 1413 | -*-fixed-medium-r-normal-*-24-*-ISO8859-1 |
| 1414 | @end example |
| 1415 | |
| 1416 | @noindent |
| 1417 | and the font specification for Chinese GB2312 characters would be this: |
| 1418 | |
| 1419 | @example |
| 1420 | -*-fixed-medium-r-normal-*-24-*-gb2312*-* |
| 1421 | @end example |
| 1422 | |
| 1423 | You may not have any Chinese font matching the above font |
| 1424 | specification. Most X distributions include only Chinese fonts that |
| 1425 | have @samp{song ti} or @samp{fangsong ti} in the @var{family} field. In |
| 1426 | such a case, @samp{Fontset-@var{n}} can be specified as: |
| 1427 | |
| 1428 | @smallexample |
| 1429 | Emacs.Fontset-0: -*-fixed-medium-r-normal-*-24-*-*-*-*-*-fontset-24,\ |
| 1430 | chinese-gb2312:-*-*-medium-r-normal-*-24-*-gb2312*-* |
| 1431 | @end smallexample |
| 1432 | |
| 1433 | @noindent |
| 1434 | Then, the font specifications for all but Chinese GB2312 characters have |
| 1435 | @samp{fixed} in the @var{family} field, and the font specification for |
| 1436 | Chinese GB2312 characters has a wild card @samp{*} in the @var{family} |
| 1437 | field. |
| 1438 | |
| 1439 | @findex create-fontset-from-fontset-spec |
| 1440 | The function that processes the fontset resource value to create the |
| 1441 | fontset is called @code{create-fontset-from-fontset-spec}. You can also |
| 1442 | call this function explicitly to create a fontset. |
| 1443 | |
| 1444 | @xref{Fonts}, for more information about font naming. |
| 1445 | |
| 1446 | @node Modifying Fontsets |
| 1447 | @section Modifying Fontsets |
| 1448 | @cindex fontsets, modifying |
| 1449 | @findex set-fontset-font |
| 1450 | |
| 1451 | Fontsets do not always have to be created from scratch. If only |
| 1452 | minor changes are required it may be easier to modify an existing |
| 1453 | fontset. Modifying @samp{fontset-default} will also affect other |
| 1454 | fontsets that use it as a fallback, so can be an effective way of |
| 1455 | fixing problems with the fonts that Emacs chooses for a particular |
| 1456 | script. |
| 1457 | |
| 1458 | Fontsets can be modified using the function @code{set-fontset-font}, |
| 1459 | specifying a character, a charset, a script, or a range of characters |
| 1460 | to modify the font for, and a font specification for the font to be |
| 1461 | used. Some examples are: |
| 1462 | |
| 1463 | @example |
| 1464 | ;; Use Liberation Mono for latin-3 charset. |
| 1465 | (set-fontset-font "fontset-default" 'iso-8859-3 |
| 1466 | "Liberation Mono") |
| 1467 | |
| 1468 | ;; Prefer a big5 font for han characters |
| 1469 | (set-fontset-font "fontset-default" |
| 1470 | 'han (font-spec :registry "big5") |
| 1471 | nil 'prepend) |
| 1472 | |
| 1473 | ;; Use DejaVu Sans Mono as a fallback in fontset-startup |
| 1474 | ;; before resorting to fontset-default. |
| 1475 | (set-fontset-font "fontset-startup" nil "DejaVu Sans Mono" |
| 1476 | nil 'append) |
| 1477 | |
| 1478 | ;; Use MyPrivateFont for the Unicode private use area. |
| 1479 | (set-fontset-font "fontset-default" '(#xe000 . #xf8ff) |
| 1480 | "MyPrivateFont") |
| 1481 | |
| 1482 | @end example |
| 1483 | |
| 1484 | |
| 1485 | @node Undisplayable Characters |
| 1486 | @section Undisplayable Characters |
| 1487 | |
| 1488 | There may be some non-@acronym{ASCII} characters that your |
| 1489 | terminal cannot display. Most text terminals support just a single |
| 1490 | character set (use the variable @code{default-terminal-coding-system} |
| 1491 | to tell Emacs which one, @ref{Terminal Coding}); characters that |
| 1492 | can't be encoded in that coding system are displayed as @samp{?} by |
| 1493 | default. |
| 1494 | |
| 1495 | Graphical displays can display a broader range of characters, but |
| 1496 | you may not have fonts installed for all of them; characters that have |
| 1497 | no font appear as a hollow box. |
| 1498 | |
| 1499 | If you use Latin-1 characters but your terminal can't display |
| 1500 | Latin-1, you can arrange to display mnemonic @acronym{ASCII} sequences |
| 1501 | instead, e.g., @samp{"o} for o-umlaut. Load the library |
| 1502 | @file{iso-ascii} to do this. |
| 1503 | |
| 1504 | @vindex latin1-display |
| 1505 | If your terminal can display Latin-1, you can display characters |
| 1506 | from other European character sets using a mixture of equivalent |
| 1507 | Latin-1 characters and @acronym{ASCII} mnemonics. Customize the variable |
| 1508 | @code{latin1-display} to enable this. The mnemonic @acronym{ASCII} |
| 1509 | sequences mostly correspond to those of the prefix input methods. |
| 1510 | |
| 1511 | @node Unibyte Mode |
| 1512 | @section Unibyte Editing Mode |
| 1513 | |
| 1514 | @cindex European character sets |
| 1515 | @cindex accented characters |
| 1516 | @cindex ISO Latin character sets |
| 1517 | @cindex Unibyte operation |
| 1518 | The ISO 8859 Latin-@var{n} character sets define character codes in |
| 1519 | the range 0240 to 0377 octal (160 to 255 decimal) to handle the |
| 1520 | accented letters and punctuation needed by various European languages |
| 1521 | (and some non-European ones). Note that Emacs considers bytes with |
| 1522 | codes in this range as raw bytes, not as characters, even in a unibyte |
| 1523 | buffer, i.e., if you disable multibyte characters. However, Emacs can |
| 1524 | still handle these character codes as if they belonged to @emph{one} |
| 1525 | of the single-byte character sets at a time. To specify @emph{which} |
| 1526 | of these codes to use, invoke @kbd{M-x set-language-environment} and |
| 1527 | specify a suitable language environment such as @samp{Latin-@var{n}}. |
| 1528 | @xref{Disabling Multibyte, , Disabling Multibyte Characters, elisp, |
| 1529 | GNU Emacs Lisp Reference Manual}. |
| 1530 | |
| 1531 | @vindex unibyte-display-via-language-environment |
| 1532 | Emacs can also display bytes in the range 160 to 255 as readable |
| 1533 | characters, provided the terminal or font in use supports them. This |
| 1534 | works automatically. On a graphical display, Emacs can also display |
| 1535 | single-byte characters through fontsets, in effect by displaying the |
| 1536 | equivalent multibyte characters according to the current language |
| 1537 | environment. To request this, set the variable |
| 1538 | @code{unibyte-display-via-language-environment} to a non-@code{nil} |
| 1539 | value. Note that setting this only affects how these bytes are |
| 1540 | displayed, but does not change the fundamental fact that Emacs treats |
| 1541 | them as raw bytes, not as characters. |
| 1542 | |
| 1543 | @cindex @code{iso-ascii} library |
| 1544 | If your terminal does not support display of the Latin-1 character |
| 1545 | set, Emacs can display these characters as @acronym{ASCII} sequences which at |
| 1546 | least give you a clear idea of what the characters are. To do this, |
| 1547 | load the library @code{iso-ascii}. Similar libraries for other |
| 1548 | Latin-@var{n} character sets could be implemented, but have not been |
| 1549 | so far. |
| 1550 | |
| 1551 | @findex standard-display-8bit |
| 1552 | @cindex 8-bit display |
| 1553 | Normally non-ISO-8859 characters (decimal codes between 128 and 159 |
| 1554 | inclusive) are displayed as octal escapes. You can change this for |
| 1555 | non-standard ``extended'' versions of ISO-8859 character sets by using the |
| 1556 | function @code{standard-display-8bit} in the @code{disp-table} library. |
| 1557 | |
| 1558 | There are two ways to input single-byte non-@acronym{ASCII} |
| 1559 | characters: |
| 1560 | |
| 1561 | @itemize @bullet |
| 1562 | @cindex 8-bit input |
| 1563 | @item |
| 1564 | You can use an input method for the selected language environment. |
| 1565 | @xref{Input Methods}. When you use an input method in a unibyte buffer, |
| 1566 | the non-@acronym{ASCII} character you specify with it is converted to unibyte. |
| 1567 | |
| 1568 | @item |
| 1569 | If your keyboard can generate character codes 128 (decimal) and up, |
| 1570 | representing non-@acronym{ASCII} characters, you can type those character codes |
| 1571 | directly. |
| 1572 | |
| 1573 | On a graphical display, you should not need to do anything special to |
| 1574 | use these keys; they should simply work. On a text terminal, you |
| 1575 | should use the command @code{M-x set-keyboard-coding-system} or customize the |
| 1576 | variable @code{keyboard-coding-system} to specify which coding system |
| 1577 | your keyboard uses (@pxref{Terminal Coding}). Enabling this feature |
| 1578 | will probably require you to use @kbd{ESC} to type Meta characters; |
| 1579 | however, on a console terminal or in @code{xterm}, you can arrange for |
| 1580 | Meta to be converted to @kbd{ESC} and still be able type 8-bit |
| 1581 | characters present directly on the keyboard or using @kbd{Compose} or |
| 1582 | @kbd{AltGr} keys. @xref{User Input}. |
| 1583 | |
| 1584 | @kindex C-x 8 |
| 1585 | @cindex @code{iso-transl} library |
| 1586 | @cindex compose character |
| 1587 | @cindex dead character |
| 1588 | @item |
| 1589 | For Latin-1 only, you can use the key @kbd{C-x 8} as a ``compose |
| 1590 | character'' prefix for entry of non-@acronym{ASCII} Latin-1 printing |
| 1591 | characters. @kbd{C-x 8} is good for insertion (in the minibuffer as |
| 1592 | well as other buffers), for searching, and in any other context where |
| 1593 | a key sequence is allowed. |
| 1594 | |
| 1595 | @kbd{C-x 8} works by loading the @code{iso-transl} library. Once that |
| 1596 | library is loaded, the @key{ALT} modifier key, if the keyboard has |
| 1597 | one, serves the same purpose as @kbd{C-x 8}: use @key{ALT} together |
| 1598 | with an accent character to modify the following letter. In addition, |
| 1599 | if the keyboard has keys for the Latin-1 ``dead accent characters'', |
| 1600 | they too are defined to compose with the following character, once |
| 1601 | @code{iso-transl} is loaded. |
| 1602 | |
| 1603 | Use @kbd{C-x 8 C-h} to list all the available @kbd{C-x 8} translations. |
| 1604 | @end itemize |
| 1605 | |
| 1606 | @node Charsets |
| 1607 | @section Charsets |
| 1608 | @cindex charsets |
| 1609 | |
| 1610 | In Emacs, @dfn{charset} is short for ``character set''. Emacs |
| 1611 | supports most popular charsets (such as @code{ascii}, |
| 1612 | @code{iso-8859-1}, @code{cp1250}, @code{big5}, and @code{unicode}), in |
| 1613 | addition to some charsets of its own (such as @code{emacs}, |
| 1614 | @code{unicode-bmp}, and @code{eight-bit}). All supported characters |
| 1615 | belong to one or more charsets. |
| 1616 | |
| 1617 | Emacs normally ``does the right thing'' with respect to charsets, so |
| 1618 | that you don't have to worry about them. However, it is sometimes |
| 1619 | helpful to know some of the underlying details about charsets. |
| 1620 | |
| 1621 | One example is font selection (@pxref{Fonts}). Each language |
| 1622 | environment (@pxref{Language Environments}) defines a ``priority |
| 1623 | list'' for the various charsets. When searching for a font, Emacs |
| 1624 | initially attempts to find one that can display the highest-priority |
| 1625 | charsets. For instance, in the Japanese language environment, the |
| 1626 | charset @code{japanese-jisx0208} has the highest priority, so Emacs |
| 1627 | tries to use a font whose @code{registry} property is |
| 1628 | @samp{JISX0208.1983-0}. |
| 1629 | |
| 1630 | @findex list-charset-chars |
| 1631 | @cindex characters in a certain charset |
| 1632 | @findex describe-character-set |
| 1633 | There are two commands that can be used to obtain information about |
| 1634 | charsets. The command @kbd{M-x list-charset-chars} prompts for a |
| 1635 | charset name, and displays all the characters in that character set. |
| 1636 | The command @kbd{M-x describe-character-set} prompts for a charset |
| 1637 | name, and displays information about that charset, including its |
| 1638 | internal representation within Emacs. |
| 1639 | |
| 1640 | @findex list-character-sets |
| 1641 | @kbd{M-x list-character-sets} displays a list of all supported |
| 1642 | charsets. The list gives the names of charsets and additional |
| 1643 | information to identity each charset; see the |
| 1644 | @url{http://www.itscj.ipsj.or.jp/ISO-IR/, International Register of |
| 1645 | Coded Character Sets} for more details. In this list, |
| 1646 | charsets are divided into two categories: @dfn{normal charsets} are |
| 1647 | listed first, followed by @dfn{supplementary charsets}. A |
| 1648 | supplementary charset is one that is used to define another charset |
| 1649 | (as a parent or a subset), or to provide backward-compatibility for |
| 1650 | older Emacs versions. |
| 1651 | |
| 1652 | To find out which charset a character in the buffer belongs to, put |
| 1653 | point before it and type @kbd{C-u C-x =} (@pxref{International |
| 1654 | Chars}). |
| 1655 | |
| 1656 | @node Bidirectional Editing |
| 1657 | @section Bidirectional Editing |
| 1658 | @cindex bidirectional editing |
| 1659 | @cindex right-to-left text |
| 1660 | |
| 1661 | Emacs supports editing text written in scripts, such as Arabic and |
| 1662 | Hebrew, whose natural ordering of horizontal text for display is from |
| 1663 | right to left. However, digits and Latin text embedded in these |
| 1664 | scripts are still displayed left to right. It is also not uncommon to |
| 1665 | have small portions of text in Arabic or Hebrew embedded in an otherwise |
| 1666 | Latin document; e.g., as comments and strings in a program source |
| 1667 | file. For these reasons, text that uses these scripts is actually |
| 1668 | @dfn{bidirectional}: a mixture of runs of left-to-right and |
| 1669 | right-to-left characters. |
| 1670 | |
| 1671 | This section describes the facilities and options provided by Emacs |
| 1672 | for editing bidirectional text. |
| 1673 | |
| 1674 | @cindex logical order |
| 1675 | @cindex visual order |
| 1676 | Emacs stores right-to-left and bidirectional text in the so-called |
| 1677 | @dfn{logical} (or @dfn{reading}) order: the buffer or string position |
| 1678 | of the first character you read precedes that of the next character. |
| 1679 | Reordering of bidirectional text into the @dfn{visual} order happens |
| 1680 | at display time. As result, character positions no longer increase |
| 1681 | monotonically with their positions on display. Emacs implements the |
| 1682 | Unicode Bidirectional Algorithm described in the Unicode Standard |
| 1683 | Annex #9, for reordering of bidirectional text for display. |
| 1684 | |
| 1685 | @vindex bidi-display-reordering |
| 1686 | The buffer-local variable @code{bidi-display-reordering} controls |
| 1687 | whether text in the buffer is reordered for display. If its value is |
| 1688 | non-@code{nil}, Emacs reorders characters that have right-to-left |
| 1689 | directionality when they are displayed. The default value is |
| 1690 | @code{t}. |
| 1691 | |
| 1692 | @cindex base direction of paragraphs |
| 1693 | @cindex paragraph, base direction |
| 1694 | Each paragraph of bidirectional text can have its own @dfn{base |
| 1695 | direction}, either right-to-left or left-to-right. (Paragraph |
| 1696 | @c paragraph-separate etc have no influence on this? |
| 1697 | boundaries are empty lines, i.e., lines consisting entirely of |
| 1698 | whitespace characters.) Text in left-to-right paragraphs begins on |
| 1699 | the screen at the left margin of the window and is truncated or |
| 1700 | continued when it reaches the right margin. By contrast, text in |
| 1701 | right-to-left paragraphs is displayed starting at the right margin and |
| 1702 | is continued or truncated at the left margin. |
| 1703 | |
| 1704 | @vindex bidi-paragraph-direction |
| 1705 | Emacs determines the base direction of each paragraph dynamically, |
| 1706 | based on the text at the beginning of the paragraph. However, |
| 1707 | sometimes a buffer may need to force a certain base direction for its |
| 1708 | paragraphs. The variable @code{bidi-paragraph-direction}, if |
| 1709 | non-@code{nil}, disables the dynamic determination of the base |
| 1710 | direction, and instead forces all paragraphs in the buffer to have the |
| 1711 | direction specified by its buffer-local value. The value can be either |
| 1712 | @code{right-to-left} or @code{left-to-right}. Any other value is |
| 1713 | interpreted as @code{nil}. |
| 1714 | |
| 1715 | @cindex LRM |
| 1716 | @cindex RLM |
| 1717 | Alternatively, you can control the base direction of a paragraph by |
| 1718 | inserting special formatting characters in front of the paragraph. |
| 1719 | The special character @code{RIGHT-TO-LEFT MARK}, or @sc{rlm}, forces |
| 1720 | the right-to-left direction on the following paragraph, while |
| 1721 | @code{LEFT-TO-RIGHT MARK}, or @sc{lrm} forces the left-to-right |
| 1722 | direction. (You can use @kbd{C-x 8 RET} to insert these characters.) |
| 1723 | In a GUI session, the @sc{lrm} and @sc{rlm} characters display as very |
| 1724 | thin blank characters; on text terminals they display as blanks. |
| 1725 | |
| 1726 | Because characters are reordered for display, Emacs commands that |
| 1727 | operate in the logical order or on stretches of buffer positions may |
| 1728 | produce unusual effects. For example, @kbd{C-f} and @kbd{C-b} |
| 1729 | commands move point in the logical order, so the cursor will sometimes |
| 1730 | jump when point traverses reordered bidirectional text. Similarly, a |
| 1731 | highlighted region covering a contiguous range of character positions |
| 1732 | may look discontinuous if the region spans reordered text. This is |
| 1733 | normal and similar to the behavior of other programs that support |
| 1734 | bidirectional text. If you set @code{visual-order-cursor-movement} to |
| 1735 | a non-@code{nil} value, cursor motion by the arrow keys follows the |
| 1736 | visual order on screen (@pxref{Moving Point, visual-order movement}). |