2068 lines
92 KiB
Plaintext
2068 lines
92 KiB
Plaintext
@c -*- coding: utf-8 -*-
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@c This is part of the Emacs manual.
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@c Copyright (C) 1997, 1999--2024 Free Software Foundation, Inc.
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@c See file emacs.texi for copying conditions.
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@node International
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@chapter International Character Set Support
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@c This node is referenced in the tutorial. When renaming or deleting
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@c it, the tutorial needs to be adjusted. (TUTORIAL.de)
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@cindex international scripts
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@cindex multibyte characters
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@cindex encoding of characters
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@cindex Han
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@cindex Hindi
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@cindex Hangul
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Emacs supports a wide variety of international character sets,
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including European and Vietnamese variants of the Latin alphabet, as
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well as Arabic scripts, Brahmic scripts (for languages such as
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Bengali, Hindi, and Thai), Cyrillic, Ethiopic, Georgian, Greek, Han
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(for Chinese and Japanese), Hangul (for Korean), Hebrew and IPA@.
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Emacs also supports various encodings of these characters that are used by
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other internationalized software, such as word processors and mailers.
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Emacs allows editing text with international characters by supporting
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all the related activities:
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@itemize @bullet
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@item
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You can visit files with non-@acronym{ASCII} characters, save non-@acronym{ASCII} text, and
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pass non-@acronym{ASCII} text between Emacs and programs it invokes (such as
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compilers, spell-checkers, and mailers). Setting your language
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environment (@pxref{Language Environments}) takes care of setting up the
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coding systems and other options for a specific language or culture.
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Alternatively, you can specify how Emacs should encode or decode text
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for each command; see @ref{Text Coding}.
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@item
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You can display non-@acronym{ASCII} characters encoded by the various
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scripts. This works by using appropriate fonts on graphics displays
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(@pxref{Defining Fontsets}), and by sending special codes to text
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displays (@pxref{Terminal Coding}). If some characters are displayed
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incorrectly, refer to @ref{Undisplayable Characters}, which describes
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possible problems and explains how to solve them.
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@item
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Characters from scripts whose natural ordering of text is from right
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to left are reordered for display (@pxref{Bidirectional Editing}).
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These scripts include Arabic, Hebrew, Syriac, Thaana, and a few
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others.
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@item
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You can insert non-@acronym{ASCII} characters or search for them. To do that,
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you can specify an Emacs input method (@pxref{Select Input Method}) suitable
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for your language, or use the default input method set up when you choose
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your language environment. If
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your keyboard can produce non-@acronym{ASCII} characters, you can select an
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appropriate keyboard coding system (@pxref{Terminal Coding}), and Emacs
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will accept those characters. On graphical displays, modern systems
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typically provide their native input methods, and Latin-1 characters
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can also be input by using the @kbd{C-x 8} prefix, see @ref{Unibyte Mode}.
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With the X Window System, your locale should be set to an appropriate
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value to make sure Emacs interprets keyboard input correctly; see
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@ref{Language Environments, locales}, and @ref{X Coding}.
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@end itemize
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The rest of this chapter describes these issues in detail.
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@menu
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* International Chars:: Basic concepts of multibyte characters.
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* Language Environments:: Setting things up for the language you use.
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* Input Methods:: Entering text characters not on your keyboard.
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* Select Input Method:: Specifying your choice of input methods.
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* Coding Systems:: Character set conversion when you read and
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write files, and so on.
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* Recognize Coding:: How Emacs figures out which conversion to use.
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* Specify Coding:: Specifying a file's coding system explicitly.
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* Output Coding:: Choosing coding systems for output.
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* Text Coding:: Choosing conversion to use for file text.
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* Communication Coding:: Coding systems for interprocess communication.
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* File Name Coding:: Coding systems for file @emph{names}.
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* X Coding:: Coding systems for X input methods.
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* Terminal Coding:: Specifying coding systems for converting
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terminal input and output.
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* Fontsets:: Fontsets are collections of fonts
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that cover the whole spectrum of characters.
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* Defining Fontsets:: Defining a new fontset.
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* Modifying Fontsets:: Modifying an existing fontset.
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* Undisplayable Characters:: When characters don't display.
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* Unibyte Mode:: You can pick one European character set
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to use without multibyte characters.
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* Charsets:: How Emacs groups its internal character codes.
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* Bidirectional Editing:: Support for right-to-left scripts.
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@end menu
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@node International Chars
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@section Introduction to International Character Sets
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The users of international character sets and scripts have
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established many more-or-less standard coding systems for storing
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files. These coding systems are typically @dfn{multibyte}, meaning
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that sequences of two or more bytes are used to represent individual
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non-@acronym{ASCII} characters.
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@cindex Unicode
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Internally, Emacs uses its own multibyte character encoding, which
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is a superset of the @dfn{Unicode} standard. This internal encoding
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allows characters from almost every known script to be intermixed in a
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single buffer or string. Emacs translates between the multibyte
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character encoding and various other coding systems when reading and
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writing files, and when exchanging data with subprocesses.
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@kindex C-h h
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@findex view-hello-file
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@cindex undisplayable characters
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@cindex @samp{?} in display
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The command @kbd{C-h h} (@code{view-hello-file}) displays the file
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@file{etc/HELLO}, which illustrates various scripts by showing
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how to say ``hello'' in many languages. If some characters can't be
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displayed on your terminal, they appear as @samp{?} or as hollow boxes
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(@pxref{Undisplayable Characters}).
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Keyboards, even in the countries where these character sets are
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used, generally don't have keys for all the characters in them. You
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can insert characters that your keyboard does not support, using
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@kbd{C-x 8 @key{RET}} (@code{insert-char}). @xref{Inserting Text}.
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Shorthands are available for some common characters; for example, you
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can insert a left single quotation mark @t{‘} by typing @kbd{C-x 8
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[}, or in Electric Quote mode, usually by simply typing @kbd{`}.
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@xref{Quotation Marks}. Emacs also supports
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various @dfn{input methods}, typically one for each script or
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language, which make it easier to type characters in the script.
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@xref{Input Methods}.
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@kindex C-x RET
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The prefix key @kbd{C-x @key{RET}} is used for commands that pertain
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to multibyte characters, coding systems, and input methods.
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@kindex C-x =@r{, and international characters}
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@findex what-cursor-position@r{, and international characters}
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The command @kbd{C-x =} (@code{what-cursor-position}) shows
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information about the character at point. In addition to the
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character position, which was described in @ref{Position Info}, this
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command displays how the character is encoded. For instance, it
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displays the following line in the echo area for the character
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@samp{c}:
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@smallexample
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Char: c (99, #o143, #x63) point=28062 of 36168 (78%) column=53
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@end smallexample
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The four values after @samp{Char:} describe the character that
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follows point, first by showing it and then by giving its character
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code in decimal, octal and hex. For a non-@acronym{ASCII} multibyte
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character, these are followed by @samp{file} and the character's
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representation, in hex, in the buffer's coding system, if that coding
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system encodes the character safely and with a single byte
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(@pxref{Coding Systems}). If the character's encoding is longer than
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one byte, Emacs shows @samp{file ...}.
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@cindex eight-bit character set
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@cindex raw bytes
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On rare occasions, Emacs encounters @dfn{raw bytes}: single bytes
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whose values are in the range 128 (0200 octal) through 255 (0377
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octal), which Emacs cannot interpret as part of a known encoding of
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some non-ASCII character. Such raw bytes are treated as if they
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belonged to a special character set @code{eight-bit}; Emacs displays
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them as escaped octal codes (this can be customized; @pxref{Display
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Custom}). In this case, @kbd{C-x =} shows @samp{raw-byte} instead of
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@samp{file}. In addition, @kbd{C-x =} shows the character codes of
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raw bytes as if they were in the range @code{#x3FFF80..#x3FFFFF},
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which is where Emacs maps them to distinguish them from Unicode
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characters in the range @code{#x0080..#x00FF}.
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@cindex character set of character at point
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@cindex font of character at point
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@cindex text properties at point
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@cindex face at point
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@findex describe-char
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With a prefix argument (@kbd{C-u C-x =}), this command additionally
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calls the command @code{describe-char}, which displays a detailed
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description of the character:
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@itemize @bullet
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@item
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The character set name, and the codes that identify the character
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within that character set; @acronym{ASCII} characters are identified
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as belonging to the @code{ascii} character set.
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@item
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The character's script, syntax and categories.
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@item
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What keys to type to input the character in the current input method
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(if it supports the character).
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@item
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The character's encodings, both internally in the buffer, and externally
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if you were to save the buffer to a file.
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@item
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If you are running Emacs on a graphical display, the font name and
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glyph code for the character. If you are running Emacs on a text
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terminal, the code(s) sent to the terminal.
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@item
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If the character was composed on display with any following characters
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to form one or more grapheme clusters, the composition information:
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the font glyphs if the frame is on a graphical display, and the
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characters that were composed.
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@item
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The character's text properties (@pxref{Text Properties,,,
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elisp, the Emacs Lisp Reference Manual}), including any non-default
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faces used to display the character, and any overlays containing it
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(@pxref{Overlays,,, elisp, the same manual}).
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@end itemize
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Here's an example, with some lines folded to fit into this manual:
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@smallexample
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position: 1 of 1 (0%), column: 0
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character: ê (displayed as ê) (codepoint 234, #o352, #xea)
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preferred charset: unicode (Unicode (ISO10646))
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code point in charset: 0xEA
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script: latin
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syntax: w which means: word
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category: .:Base, L:Left-to-right (strong), c:Chinese,
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j:Japanese, l:Latin, v:Viet
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to input: type "C-x 8 RET ea" or
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"C-x 8 RET LATIN SMALL LETTER E WITH CIRCUMFLEX"
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buffer code: #xC3 #xAA
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file code: #xC3 #xAA (encoded by coding system utf-8-unix)
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display: by this font (glyph code)
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xft:-PfEd-DejaVu Sans Mono-normal-normal-
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normal-*-15-*-*-*-m-0-iso10646-1 (#xAC)
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Character code properties: customize what to show
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name: LATIN SMALL LETTER E WITH CIRCUMFLEX
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old-name: LATIN SMALL LETTER E CIRCUMFLEX
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general-category: Ll (Letter, Lowercase)
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decomposition: (101 770) ('e' '^')
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@end smallexample
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@node Language Environments
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@section Language Environments
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@cindex language environments
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All supported character sets are supported in Emacs buffers whenever
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multibyte characters are enabled; there is no need to select a
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particular language in order to display its characters.
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However, it is important to select a @dfn{language
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environment} in order to set various defaults. Roughly speaking, the
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language environment represents a choice of preferred script rather
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than a choice of language.
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The language environment controls which coding systems to recognize
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when reading text (@pxref{Recognize Coding}). This applies to files,
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incoming mail, and any other text you read into Emacs. It may also
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specify the default coding system to use when you create a file. Each
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language environment also specifies a default input method.
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@findex set-language-environment
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@vindex current-language-environment
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To select a language environment, customize
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@code{current-language-environment} or use the command @kbd{M-x
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set-language-environment}. It makes no difference which buffer is
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current when you use this command, because the effects apply globally
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to the Emacs session. See the variable @code{language-info-alist} for
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the list of supported language environments, and use the command
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@kbd{C-h L @var{lang-env} @key{RET}} (@code{describe-language-environment})
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for more information about the language environment @var{lang-env}.
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Supported language environments include:
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@c @cindex entries below are split between portions of the list to
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@c make them more accurate, i.e., land on the line that mentions the
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@c language. However, makeinfo 4.x doesn't fill inside @quotation
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@c lines that follow a @cindex entry and whose text has no whitespace.
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@c To work around, we group the language environments together, so
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@c that the blank that separates them triggers refill.
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@quotation
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@cindex ASCII (language environment)
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@cindex Arabic
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ASCII, Arabic,
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@cindex Belarusian
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@cindex Bengali
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Belarusian, Bengali,
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@cindex Brazilian Portuguese
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@cindex Bulgarian
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Brazilian Portuguese, Bulgarian,
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@cindex Burmese
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@cindex Cham
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Burmese, Cham,
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@cindex Chinese
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Chinese-BIG5, Chinese-CNS, Chinese-EUC-TW, Chinese-GB,
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Chinese-GB18030, Chinese-GBK,
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@cindex Croatian
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@cindex Cyrillic
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Croatian, Cyrillic-ALT, Cyrillic-ISO, Cyrillic-KOI8,
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@cindex Czech
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@cindex Devanagari
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Czech, Devanagari,
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@cindex Dutch
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@cindex English
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Dutch, English,
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@cindex Esperanto
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@cindex Ethiopic
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Esperanto, Ethiopic,
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@cindex French
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@cindex Georgian
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French, Georgian,
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@cindex German
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@cindex Greek
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@cindex Gujarati
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German, Greek, Gujarati,
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@cindex Hebrew
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@cindex IPA
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Hebrew, IPA,
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@cindex Italian
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Italian,
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@cindex Japanese
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@cindex Kannada
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Japanese, Kannada,
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@cindex Khmer
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@cindex Korean
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@cindex Lao
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Khmer, Korean, Lao,
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@cindex Latin
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Latin-1, Latin-2, Latin-3, Latin-4, Latin-5, Latin-6, Latin-7,
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Latin-8, Latin-9,
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@cindex Latvian
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@cindex Lithuanian
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Latvian, Lithuanian,
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@cindex Malayalam
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@cindex Oriya
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Malayalam, Oriya,
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@cindex Persian
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@cindex Polish
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Persian, Polish,
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@cindex Punjabi
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@cindex Romanian
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Punjabi, Romanian,
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@cindex Russian
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@cindex Sinhala
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Russian, Sinhala,
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@cindex Slovak
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@cindex Slovenian
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@cindex Spanish
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Slovak, Slovenian, Spanish,
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@cindex Swedish
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@cindex TaiViet
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Swedish, TaiViet,
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@cindex Tajik
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@cindex Tamil
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Tajik, Tamil,
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@cindex Telugu
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@cindex Thai
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Telugu, Thai,
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@cindex Tibetan
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@cindex Turkish
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Tibetan, Turkish,
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@cindex UTF-8
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@cindex Ukrainian
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UTF-8, Ukrainian,
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@cindex Vietnamese
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@cindex Welsh
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Vietnamese, Welsh,
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@cindex Windows-1255
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and Windows-1255.
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@end quotation
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To display the script(s) used by your language environment on a
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graphical display, you need to have suitable fonts.
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@xref{Fontsets}, for more details about setting up your fonts.
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@findex set-locale-environment
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@vindex locale-language-names
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@vindex locale-charset-language-names
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@cindex locales
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Some operating systems let you specify the character-set locale you
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are using by setting the locale environment variables @env{LC_ALL},
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@env{LC_CTYPE}, or @env{LANG}. (If more than one of these is
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set, the first one that is nonempty specifies your locale for this
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purpose.) During startup, Emacs looks up your character-set locale's
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name in the system locale alias table, matches its canonical name
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against entries in the value of the variables
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@code{locale-charset-language-names} and @code{locale-language-names}
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(the former overrides the latter),
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and selects the corresponding language environment if a match is found.
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It also adjusts the display
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table and terminal coding system, the locale coding system, the
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preferred coding system as needed for the locale, and---last but not
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least---the way Emacs decodes non-@acronym{ASCII} characters sent by your keyboard.
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@c This seems unlikely, doesn't it?
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If you modify the @env{LC_ALL}, @env{LC_CTYPE}, or @env{LANG}
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environment variables while running Emacs (by using @kbd{M-x setenv}),
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you may want to invoke the @code{set-locale-environment}
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command afterwards to readjust the language environment from the new
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locale.
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@vindex locale-preferred-coding-systems
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The @code{set-locale-environment} function normally uses the preferred
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coding system established by the language environment to decode system
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messages. But if your locale matches an entry in the variable
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@code{locale-preferred-coding-systems}, Emacs uses the corresponding
|
||
coding system instead. For example, if the locale @samp{ja_JP.PCK}
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matches @code{japanese-shift-jis} in
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@code{locale-preferred-coding-systems}, Emacs uses that encoding even
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||
though it might normally use @code{utf-8}.
|
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|
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You can override the language environment chosen at startup with
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explicit use of the command @code{set-language-environment}, or with
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customization of @code{current-language-environment} in your init
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file.
|
||
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@kindex C-h L
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@findex describe-language-environment
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||
To display information about the effects of a certain language
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||
environment @var{lang-env}, use the command @kbd{C-h L @var{lang-env}
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||
@key{RET}} (@code{describe-language-environment}). This tells you
|
||
which languages this language environment is useful for, and lists the
|
||
character sets, coding systems, and input methods that go with it. It
|
||
also shows some sample text to illustrate scripts used in this
|
||
language environment. If you give an empty input for @var{lang-env},
|
||
this command describes the chosen language environment.
|
||
|
||
@vindex set-language-environment-hook
|
||
You can customize any language environment with the normal hook
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||
@code{set-language-environment-hook}. The command
|
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@code{set-language-environment} runs that hook after setting up the new
|
||
language environment. The hook functions can test for a specific
|
||
language environment by checking the variable
|
||
@code{current-language-environment}. This hook is where you should
|
||
put non-default settings for specific language environments, such as
|
||
coding systems for keyboard input and terminal output, the default
|
||
input method, etc.
|
||
|
||
@vindex exit-language-environment-hook
|
||
Before it starts to set up the new language environment,
|
||
@code{set-language-environment} first runs the hook
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||
@code{exit-language-environment-hook}. This hook is useful for undoing
|
||
customizations that were made with @code{set-language-environment-hook}.
|
||
For instance, if you set up a special key binding in a specific language
|
||
environment using @code{set-language-environment-hook}, you should set
|
||
up @code{exit-language-environment-hook} to restore the normal binding
|
||
for that key.
|
||
|
||
@node Input Methods
|
||
@section Input Methods
|
||
|
||
@cindex input methods
|
||
An @dfn{input method} is a kind of character conversion designed
|
||
specifically for interactive input. This section describes input
|
||
methods that come with Emacs; for native input methods provided by the
|
||
underlying OS, @pxref{Unibyte Mode}.
|
||
|
||
In Emacs, typically each language has its own input method;
|
||
sometimes several languages that use the same characters can share one
|
||
input method. A few languages support several input methods.
|
||
|
||
The simplest kind of input method works by mapping @acronym{ASCII} letters
|
||
into another alphabet; this allows you to use one other alphabet
|
||
instead of @acronym{ASCII}. The Greek and Russian input methods
|
||
work this way.
|
||
|
||
A more powerful technique is composition: converting sequences of
|
||
characters into one letter. Many European input methods use composition
|
||
to produce a single non-@acronym{ASCII} letter from a sequence that consists of a
|
||
letter followed by accent characters (or vice versa). For example, some
|
||
methods convert the sequence @kbd{o ^} into a single accented letter.
|
||
These input methods have no special commands of their own; all they do
|
||
is compose sequences of printing characters.
|
||
|
||
The input methods for syllabic scripts typically use mapping followed
|
||
by composition. The input methods for Thai and Korean work this way.
|
||
First, letters are mapped into symbols for particular sounds or tone
|
||
marks; then, sequences of these that make up a whole syllable are
|
||
mapped into one syllable sign.
|
||
|
||
@kindex C-f@r{, when using input methods}
|
||
@kindex C-b@r{, when using input methods}
|
||
@kindex C-n@r{, when using input methods}
|
||
@kindex C-p@r{, when using input methods}
|
||
Chinese and Japanese require more complex methods. In Chinese input
|
||
methods, first you enter the phonetic spelling of a Chinese word (in
|
||
input method @code{chinese-py}, among others), or a sequence of
|
||
portions of the character (input methods @code{chinese-4corner} and
|
||
@code{chinese-sw}, and others). One input sequence typically
|
||
corresponds to many possible Chinese characters. You select the one
|
||
you mean using keys such as @kbd{C-f}, @kbd{C-b}, @kbd{C-n},
|
||
@kbd{C-p} (or the arrow keys), and digits, which have special meanings
|
||
in this situation.
|
||
|
||
The possible characters are conceptually arranged in several rows,
|
||
with each row holding up to 10 alternatives. Normally, Emacs displays
|
||
just one row at a time, in the echo area; @code{(@var{i}/@var{j})}
|
||
appears at the beginning, to indicate that this is the @var{i}th row
|
||
out of a total of @var{j} rows. Type @kbd{C-n} or @kbd{C-p} to
|
||
display the next row or the previous row.
|
||
|
||
Type @kbd{C-f} and @kbd{C-b} to move forward and backward among
|
||
the alternatives in the current row. As you do this, Emacs highlights
|
||
the current alternative with a special color; type @kbd{C-@key{SPC}}
|
||
to select the current alternative and use it as input. The
|
||
alternatives in the row are also numbered; the number appears before
|
||
the alternative. Typing a number selects the associated alternative
|
||
of the current row and uses it as input.
|
||
|
||
@kindex TAB@r{, when using Chinese input methods}
|
||
@key{TAB} in these Chinese input methods displays a buffer showing
|
||
all the possible characters at once; then clicking @kbd{mouse-2} on
|
||
one of them selects that alternative. The keys @kbd{C-f}, @kbd{C-b},
|
||
@kbd{C-n}, @kbd{C-p}, and digits continue to work as usual, but they
|
||
do the highlighting in the buffer showing the possible characters,
|
||
rather than in the echo area.
|
||
|
||
To enter characters according to the @dfn{p@=iny@=in} transliteration
|
||
method instead, use the @code{chinese-sisheng} input method. This is
|
||
a composition based method, where e.g. @kbd{pi1} results in @samp{p@=i}.
|
||
|
||
In Japanese input methods, first you input a whole word using
|
||
phonetic spelling; then, after the word is in the buffer, Emacs
|
||
converts it into one or more characters using a large dictionary. One
|
||
phonetic spelling corresponds to a number of different Japanese words;
|
||
to select one of them, use @kbd{C-n} and @kbd{C-p} to cycle through
|
||
the alternatives.
|
||
|
||
Sometimes it is useful to cut off input method processing so that the
|
||
characters you have just entered will not combine with subsequent
|
||
characters. For example, in input method @code{latin-1-postfix}, the
|
||
sequence @kbd{o ^} combines to form an @samp{o} with an accent. What if
|
||
you want to enter them as separate characters?
|
||
|
||
One way is to type the accent twice; this is a special feature for
|
||
entering the separate letter and accent. For example, @kbd{o ^ ^} gives
|
||
you the two characters @samp{o^}. Another way is to type another letter
|
||
after the @kbd{o}---something that won't combine with that---and
|
||
immediately delete it. For example, you could type @kbd{o o @key{DEL}
|
||
^} to get separate @samp{o} and @samp{^}. Another method, more
|
||
general but not quite as easy to type, is to use @kbd{C-\ C-\} between
|
||
two characters to stop them from combining. This is the command
|
||
@kbd{C-\} (@code{toggle-input-method}) used twice.
|
||
@ifnottex
|
||
@xref{Select Input Method}.
|
||
@end ifnottex
|
||
|
||
@cindex incremental search, input method interference
|
||
@kbd{C-\ C-\} is especially useful inside an incremental search,
|
||
because it stops waiting for more characters to combine, and starts
|
||
searching for what you have already entered.
|
||
|
||
To find out how to input the character after point using the current
|
||
input method, type @kbd{C-u C-x =}. @xref{Position Info}.
|
||
|
||
@c TODO: document complex-only/default/t of
|
||
@c @code{input-method-verbose-flag}
|
||
@vindex input-method-verbose-flag
|
||
@vindex input-method-highlight-flag
|
||
The variables @code{input-method-highlight-flag} and
|
||
@code{input-method-verbose-flag} control how input methods explain
|
||
what is happening. If @code{input-method-highlight-flag} is
|
||
non-@code{nil}, the partial sequence is highlighted in the buffer (for
|
||
most input methods---some disable this feature). If
|
||
@code{input-method-verbose-flag} is non-@code{nil}, the list of
|
||
possible characters to type next is displayed in the echo area (but
|
||
not when you are in the minibuffer).
|
||
|
||
@vindex quail-activate-hook
|
||
@findex quail-translation-keymap
|
||
You can modify how an input method works by making your changes in a
|
||
function that you add to the hook variable @code{quail-activate-hook}.
|
||
@xref{Hooks}. For example, you can redefine some of the input
|
||
method's keys by defining key bindings in the keymap returned by the
|
||
function @code{quail-translation-keymap}, using @code{define-key}.
|
||
@xref{Init Rebinding}.
|
||
|
||
Input methods are inhibited when the text in the buffer is read-only
|
||
for some reason. This is so single-character key bindings work in
|
||
modes that make buffer text or parts of it read-only, such as
|
||
@code{read-only-mode} and @code{image-mode}, even when an input method
|
||
is active.
|
||
|
||
@kindex C-x 8 @key{RET}
|
||
@cindex insert character by name or code-point
|
||
Another facility for typing characters not on your keyboard is by
|
||
using @kbd{C-x 8 @key{RET}} (@code{insert-char}) to insert a single
|
||
character based on its Unicode name or code-point; see @ref{Inserting
|
||
Text}.
|
||
|
||
@cindex emoji input
|
||
@cindex inserting Emoji
|
||
@kindex C-x 8 e
|
||
@findex emoji-insert
|
||
@findex emoji-list
|
||
@findex emoji-search
|
||
There are specialized commands for inserting Emoji, and these can be
|
||
found on the @kbd{C-x 8 e} keymap. @kbd{C-x 8 e e}
|
||
(@code{emoji-insert}) will let you navigate through different Emoji
|
||
categories and then choose one. @kbd{C-x 8 e l} (@code{emoji-list})
|
||
will pop up a new buffer and list all the Emoji; clicking (or using
|
||
@kbd{RET}) on an emoji character will insert it in the current buffer.
|
||
Finally, @kbd{C-x 8 e s} (@code{emoji-search}) will allow you to
|
||
search for Emoji based on their names.
|
||
|
||
@findex emoji-describe
|
||
@code{describe-char} displays a lot of information about the
|
||
character/glyphs under point (including emojis). It's sometimes
|
||
useful to get a quick description of the name, and you can use the
|
||
@kbd{C-x 8 e d} (@code{emoji-describe}) command to do that. It's
|
||
meant primarily to help distinguish between different Emoji
|
||
variants (which can look very similar), but it will also tell you
|
||
the names of non-Emoji characters.
|
||
|
||
@node Select Input Method
|
||
@section Selecting an Input Method
|
||
|
||
@table @kbd
|
||
@item C-\
|
||
Enable or disable use of the selected input method (@code{toggle-input-method}).
|
||
|
||
@item C-x @key{RET} C-\ @var{method} @key{RET}
|
||
Select a new input method for the current buffer (@code{set-input-method}).
|
||
|
||
@item C-x \ @var{method} @key{RET}
|
||
Temporarily enable the selected transient input method ; it will be
|
||
automatically disabled after inserting a single character
|
||
(@code{activate-transient-input-method}).
|
||
|
||
@item C-h I @var{method} @key{RET}
|
||
@itemx C-h C-\ @var{method} @key{RET}
|
||
@findex describe-input-method
|
||
@kindex C-h I
|
||
@kindex C-h C-\
|
||
Describe the input method @var{method} (@code{describe-input-method}).
|
||
By default, it describes the current input method (if any). This
|
||
description should give you the full details of how to use any
|
||
particular input method.
|
||
|
||
@item M-x list-input-methods
|
||
Display a list of all the supported input methods.
|
||
@end table
|
||
|
||
@findex set-input-method
|
||
@vindex current-input-method
|
||
@kindex C-x RET C-\
|
||
To choose an input method for the current buffer, use @kbd{C-x
|
||
@key{RET} C-\} (@code{set-input-method}). This command reads the
|
||
input method name from the minibuffer; the name normally starts with the
|
||
language environment that it is meant to be used with. The variable
|
||
@code{current-input-method} records which input method is selected.
|
||
|
||
@findex toggle-input-method
|
||
@kindex C-\
|
||
Input methods use various sequences of @acronym{ASCII} characters to
|
||
stand for non-@acronym{ASCII} characters. Sometimes it is useful to
|
||
turn off the input method temporarily. To do this, type @kbd{C-\}
|
||
(@code{toggle-input-method}). To reenable the input method, type
|
||
@kbd{C-\} again.
|
||
|
||
If you type @kbd{C-\} and you have not yet selected an input method,
|
||
it prompts you to specify one. This has the same effect as using
|
||
@kbd{C-x @key{RET} C-\} to specify an input method.
|
||
|
||
When invoked with a numeric argument, as in @kbd{C-u C-\},
|
||
@code{toggle-input-method} always prompts you for an input method,
|
||
suggesting the most recently selected one as the default.
|
||
|
||
@vindex default-input-method
|
||
Selecting a language environment specifies a default input method for
|
||
use in various buffers. When you have a default input method, you can
|
||
select it in the current buffer by typing @kbd{C-\}. The variable
|
||
@code{default-input-method} specifies the default input method
|
||
(@code{nil} means there is none).
|
||
|
||
In some language environments, which support several different input
|
||
methods, you might want to use an input method different from the
|
||
default chosen by @code{set-language-environment}. You can instruct
|
||
Emacs to select a different default input method for a certain
|
||
language environment, if you wish, by using
|
||
@code{set-language-environment-hook} (@pxref{Language Environments,
|
||
set-language-environment-hook}). For example:
|
||
|
||
@lisp
|
||
(defun my-chinese-setup ()
|
||
"Set up my private Chinese environment."
|
||
(if (equal current-language-environment "Chinese-GB")
|
||
(setq default-input-method "chinese-tonepy")))
|
||
(add-hook 'set-language-environment-hook 'my-chinese-setup)
|
||
@end lisp
|
||
|
||
@noindent
|
||
This sets the default input method to be @code{chinese-tonepy}
|
||
whenever you choose a Chinese-GB language environment.
|
||
|
||
You can instruct Emacs to activate a certain input method
|
||
automatically. For example:
|
||
|
||
@lisp
|
||
(add-hook 'text-mode-hook
|
||
(lambda () (set-input-method "german-prefix")))
|
||
@end lisp
|
||
|
||
@noindent
|
||
This automatically activates the input method @code{german-prefix} in
|
||
Text mode.
|
||
|
||
@findex quail-set-keyboard-layout
|
||
Some input methods for alphabetic scripts work by (in effect)
|
||
remapping the keyboard to emulate various keyboard layouts commonly used
|
||
for those scripts. How to do this remapping properly depends on your
|
||
actual keyboard layout. To specify which layout your keyboard has, use
|
||
the command @kbd{M-x quail-set-keyboard-layout}.
|
||
|
||
@findex quail-show-key
|
||
You can use the command @kbd{M-x quail-show-key} to show what key (or
|
||
key sequence) to type in order to input the character following point,
|
||
using the selected keyboard layout. The command @kbd{C-u C-x =} also
|
||
shows that information, in addition to other information about the
|
||
character.
|
||
|
||
@findex list-input-methods
|
||
@kbd{M-x list-input-methods} displays a list of all the supported
|
||
input methods. The list gives information about each input method,
|
||
including the string that stands for it in the mode line.
|
||
|
||
@findex activate-transient-input-method
|
||
@kindex C-x \
|
||
@anchor{transient input method}
|
||
Sometimes it can be convenient to enable an input method
|
||
@dfn{transiently}, for inserting only a single character. Typing
|
||
@kbd{C-x \} (@code{activate-transient-input-method}) will temporarily
|
||
enable an input method, let you insert a single character using the input
|
||
method rules, and then automatically disable the input method. If no
|
||
transient input method was selected yet, @kbd{C-x \} will prompt you
|
||
for an input method; subsequent invocations of this command will
|
||
enable the selected transient input method. To select a different
|
||
transient input method, type @kbd{C-u C-x \}. You can select a
|
||
transient method that is different from the input method which you
|
||
selected using @kbd{C-u C-\}.
|
||
|
||
@node Coding Systems
|
||
@section Coding Systems
|
||
@cindex coding systems
|
||
|
||
Users of various languages have established many more-or-less standard
|
||
coding systems for representing them. Emacs does not use these coding
|
||
systems internally; instead, it converts from various coding systems to
|
||
its own system when reading data, and converts the internal coding
|
||
system to other coding systems when writing data. Conversion is
|
||
possible in reading or writing files, in sending or receiving from the
|
||
terminal, and in exchanging data with subprocesses.
|
||
|
||
Emacs assigns a name to each coding system. Most coding systems are
|
||
used for one language, and the name of the coding system starts with
|
||
the language name. Some coding systems are used for several
|
||
languages; their names usually start with @samp{iso}. There are also
|
||
special coding systems, such as @code{no-conversion}, @code{raw-text},
|
||
and @code{emacs-internal}.
|
||
|
||
@cindex international files from DOS/Windows systems
|
||
A special class of coding systems, collectively known as
|
||
@dfn{codepages}, is designed to support text encoded by MS-Windows and
|
||
MS-DOS software. The names of these coding systems are
|
||
@code{cp@var{nnnn}}, where @var{nnnn} is a 3- or 4-digit number of the
|
||
codepage. You can use these encodings just like any other coding
|
||
system; for example, to visit a file encoded in codepage 850, type
|
||
@kbd{C-x @key{RET} c cp850 @key{RET} C-x C-f @var{filename}
|
||
@key{RET}}.
|
||
|
||
In addition to converting various representations of non-@acronym{ASCII}
|
||
characters, a coding system can perform end-of-line conversion. Emacs
|
||
handles three different conventions for how to separate lines in a file:
|
||
newline (Unix), carriage return followed by linefeed (DOS), and just
|
||
carriage return (Mac).
|
||
|
||
@table @kbd
|
||
@item C-h C @var{coding} @key{RET}
|
||
Describe coding system @var{coding} (@code{describe-coding-system}).
|
||
|
||
@item C-h C @key{RET}
|
||
Describe the coding systems currently in use (@code{describe-coding-system}).
|
||
|
||
@item M-x list-coding-systems
|
||
Display a list of all the supported coding systems.
|
||
@end table
|
||
|
||
@kindex C-h C
|
||
@findex describe-coding-system
|
||
The command @kbd{C-h C} (@code{describe-coding-system}) displays
|
||
information about particular coding systems, including the end-of-line
|
||
conversion specified by those coding systems. You can specify a coding
|
||
system name as the argument; alternatively, with an empty argument, it
|
||
describes the coding systems currently selected for various purposes,
|
||
both in the current buffer and as the defaults, and the priority list
|
||
for recognizing coding systems (@pxref{Recognize Coding}).
|
||
|
||
@findex list-coding-systems
|
||
To display a list of all the supported coding systems, type @kbd{M-x
|
||
list-coding-systems}. The list gives information about each coding
|
||
system, including the letter that stands for it in the mode line
|
||
(@pxref{Mode Line}).
|
||
|
||
@cindex end-of-line conversion
|
||
@cindex line endings
|
||
@cindex MS-DOS end-of-line conversion
|
||
@cindex Macintosh end-of-line conversion
|
||
Each of the coding systems that appear in this list---except for
|
||
@code{no-conversion}, which means no conversion of any kind---specifies
|
||
how and whether to convert printing characters, but leaves the choice of
|
||
end-of-line conversion to be decided based on the contents of each file.
|
||
For example, if the file appears to use the sequence carriage return
|
||
and linefeed to separate lines, DOS end-of-line conversion will be used.
|
||
|
||
Each of the listed coding systems has three variants, which specify
|
||
exactly what to do for end-of-line conversion:
|
||
|
||
@table @code
|
||
@item @dots{}-unix
|
||
Don't do any end-of-line conversion; assume the file uses
|
||
newline to separate lines. (This is the convention normally used
|
||
on Unix and GNU systems, and macOS.)
|
||
|
||
@item @dots{}-dos
|
||
Assume the file uses carriage return followed by linefeed to separate
|
||
lines, and do the appropriate conversion. (This is the convention
|
||
normally used on Microsoft systems.@footnote{It is also specified for
|
||
MIME @samp{text/*} bodies and in other network transport contexts. It
|
||
is different from the SGML reference syntax record-start/record-end
|
||
format, which Emacs doesn't support directly.})
|
||
|
||
@item @dots{}-mac
|
||
Assume the file uses carriage return to separate lines, and do the
|
||
appropriate conversion. (This was the convention used in Classic Mac
|
||
OS.)
|
||
@end table
|
||
|
||
These variant coding systems are omitted from the
|
||
@code{list-coding-systems} display for brevity, since they are entirely
|
||
predictable. For example, the coding system @code{iso-latin-1} has
|
||
variants @code{iso-latin-1-unix}, @code{iso-latin-1-dos} and
|
||
@code{iso-latin-1-mac}.
|
||
|
||
@cindex @code{undecided}, coding system
|
||
The coding systems @code{unix}, @code{dos}, and @code{mac} are
|
||
aliases for @code{undecided-unix}, @code{undecided-dos}, and
|
||
@code{undecided-mac}, respectively. These coding systems specify only
|
||
the end-of-line conversion, and leave the character code conversion to
|
||
be deduced from the text itself.
|
||
|
||
@cindex @code{raw-text}, coding system
|
||
The coding system @code{raw-text} is good for a file which is mainly
|
||
@acronym{ASCII} text, but may contain byte values above 127 that are
|
||
not meant to encode non-@acronym{ASCII} characters. With
|
||
@code{raw-text}, Emacs copies those byte values unchanged, and sets
|
||
@code{enable-multibyte-characters} to @code{nil} in the current buffer
|
||
so that they will be interpreted properly. @code{raw-text} handles
|
||
end-of-line conversion in the usual way, based on the data
|
||
encountered, and has the usual three variants to specify the kind of
|
||
end-of-line conversion to use.
|
||
|
||
@cindex @code{no-conversion}, coding system
|
||
In contrast, the coding system @code{no-conversion} specifies no
|
||
character code conversion at all---none for non-@acronym{ASCII} byte values and
|
||
none for end of line. This is useful for reading or writing binary
|
||
files, tar files, and other files that must be examined verbatim. It,
|
||
too, sets @code{enable-multibyte-characters} to @code{nil}.
|
||
|
||
The easiest way to edit a file with no conversion of any kind is with
|
||
the @kbd{M-x find-file-literally} command. This uses
|
||
@code{no-conversion}, and also suppresses other Emacs features that
|
||
might convert the file contents before you see them. @xref{Visiting}.
|
||
|
||
@cindex @code{emacs-internal}, coding system
|
||
The coding system @code{emacs-internal} (or @code{utf-8-emacs},
|
||
which is equivalent) means that the file contains non-@acronym{ASCII}
|
||
characters stored with the internal Emacs encoding. This coding
|
||
system handles end-of-line conversion based on the data encountered,
|
||
and has the usual three variants to specify the kind of end-of-line
|
||
conversion.
|
||
|
||
@node Recognize Coding
|
||
@section Recognizing Coding Systems
|
||
|
||
Whenever Emacs reads a given piece of text, it tries to recognize
|
||
which coding system to use. This applies to files being read, output
|
||
from subprocesses, text from X selections, etc. Emacs can select the
|
||
right coding system automatically most of the time---once you have
|
||
specified your preferences.
|
||
|
||
Some coding systems can be recognized or distinguished by which byte
|
||
sequences appear in the data. However, there are coding systems that
|
||
cannot be distinguished, not even potentially. For example, there is no
|
||
way to distinguish between Latin-1 and Latin-2; they use the same byte
|
||
values with different meanings.
|
||
|
||
Emacs handles this situation by means of a priority list of coding
|
||
systems. Whenever Emacs reads a file, if you do not specify the coding
|
||
system to use, Emacs checks the data against each coding system,
|
||
starting with the first in priority and working down the list, until it
|
||
finds a coding system that fits the data. Then it converts the file
|
||
contents assuming that they are represented in this coding system.
|
||
|
||
The priority list of coding systems depends on the selected language
|
||
environment (@pxref{Language Environments}). For example, if you use
|
||
French, you probably want Emacs to prefer Latin-1 to Latin-2; if you use
|
||
Czech, you probably want Latin-2 to be preferred. This is one of the
|
||
reasons to specify a language environment.
|
||
|
||
@findex prefer-coding-system
|
||
However, you can alter the coding system priority list in detail
|
||
with the command @kbd{M-x prefer-coding-system}. This command reads
|
||
the name of a coding system from the minibuffer, and adds it to the
|
||
front of the priority list, so that it is preferred to all others. If
|
||
you use this command several times, each use adds one element to the
|
||
front of the priority list.
|
||
|
||
If you use a coding system that specifies the end-of-line conversion
|
||
type, such as @code{iso-8859-1-dos}, what this means is that Emacs
|
||
should attempt to recognize @code{iso-8859-1} with priority, and should
|
||
use DOS end-of-line conversion when it does recognize @code{iso-8859-1}.
|
||
|
||
@vindex file-coding-system-alist
|
||
Sometimes a file name indicates which coding system to use for the
|
||
file. The variable @code{file-coding-system-alist} specifies this
|
||
correspondence. There is a special function
|
||
@code{modify-coding-system-alist} for adding elements to this list. For
|
||
example, to read and write all @samp{.txt} files using the coding system
|
||
@code{chinese-iso-8bit}, you can execute this Lisp expression:
|
||
|
||
@smallexample
|
||
(modify-coding-system-alist 'file "\\.txt\\'" 'chinese-iso-8bit)
|
||
@end smallexample
|
||
|
||
@noindent
|
||
The first argument should be @code{file}, the second argument should be
|
||
a regular expression that determines which files this applies to, and
|
||
the third argument says which coding system to use for these files.
|
||
|
||
@vindex inhibit-eol-conversion
|
||
@cindex DOS-style end-of-line display
|
||
Emacs recognizes which kind of end-of-line conversion to use based on
|
||
the contents of the file: if it sees only carriage returns, or only
|
||
carriage return followed by linefeed sequences, then it chooses the
|
||
end-of-line conversion accordingly. You can inhibit the automatic use
|
||
of end-of-line conversion by setting the variable
|
||
@code{inhibit-eol-conversion} to non-@code{nil}. If you do that,
|
||
DOS-style files will be displayed with the @samp{^M} characters
|
||
visible in the buffer; some people prefer this to the more subtle
|
||
@samp{(DOS)} end-of-line type indication near the left edge of the
|
||
mode line (@pxref{Mode Line, eol-mnemonic}).
|
||
|
||
@vindex inhibit-iso-escape-detection
|
||
@cindex escape sequences in files
|
||
By default, the automatic detection of the coding system is sensitive to
|
||
escape sequences. If Emacs sees a sequence of characters that begin
|
||
with an escape character, and the sequence is valid as an ISO-2022
|
||
code, that tells Emacs to use one of the ISO-2022 encodings to decode
|
||
the file.
|
||
|
||
However, there may be cases that you want to read escape sequences
|
||
in a file as is. In such a case, you can set the variable
|
||
@code{inhibit-iso-escape-detection} to non-@code{nil}. Then the code
|
||
detection ignores any escape sequences, and never uses an ISO-2022
|
||
encoding. The result is that all escape sequences become visible in
|
||
the buffer.
|
||
|
||
The default value of @code{inhibit-iso-escape-detection} is
|
||
@code{nil}. We recommend that you not change it permanently, only for
|
||
one specific operation. That's because some Emacs Lisp source files
|
||
in the Emacs distribution contain non-@acronym{ASCII} characters encoded in the
|
||
coding system @code{iso-2022-7bit}, and they won't be
|
||
decoded correctly when you visit those files if you suppress the
|
||
escape sequence detection.
|
||
@c I count a grand total of 3 such files, so is the above really true?
|
||
|
||
@vindex auto-coding-alist
|
||
@vindex auto-coding-regexp-alist
|
||
The variables @code{auto-coding-alist} and
|
||
@code{auto-coding-regexp-alist} are
|
||
the strongest way to specify the coding system for certain patterns of
|
||
file names, or for files containing certain patterns, respectively.
|
||
These variables even override @samp{-*-coding:-*-} tags in the file
|
||
itself (@pxref{Specify Coding}). For example, Emacs
|
||
uses @code{auto-coding-alist} for tar and archive files, to prevent it
|
||
from being confused by a @samp{-*-coding:-*-} tag in a member of the
|
||
archive and thinking it applies to the archive file as a whole.
|
||
@ignore
|
||
@c This describes old-style BABYL files, which are no longer relevant.
|
||
Likewise, Emacs uses @code{auto-coding-regexp-alist} to ensure that
|
||
RMAIL files, whose names in general don't match any particular
|
||
pattern, are decoded correctly.
|
||
@end ignore
|
||
|
||
@vindex auto-coding-functions
|
||
Another way to specify a coding system is with the variable
|
||
@code{auto-coding-functions}. For example, one of the builtin
|
||
@code{auto-coding-functions} detects the encoding for XML files.
|
||
Unlike the previous two, this variable does not override any
|
||
@samp{-*-coding:-*-} tag.
|
||
|
||
@node Specify Coding
|
||
@section Specifying a File's Coding System
|
||
|
||
If Emacs recognizes the encoding of a file incorrectly, you can
|
||
reread the file using the correct coding system with @kbd{C-x
|
||
@key{RET} r} (@code{revert-buffer-with-coding-system}). This command
|
||
prompts for the coding system to use. To see what coding system Emacs
|
||
actually used to decode the file, look at the coding system mnemonic
|
||
letter near the left edge of the mode line (@pxref{Mode Line}), or
|
||
type @kbd{C-h C} (@code{describe-coding-system}).
|
||
|
||
@vindex coding
|
||
You can specify the coding system for a particular file in the file
|
||
itself, using the @w{@samp{-*-@dots{}-*-}} construct at the beginning,
|
||
or a local variables list at the end (@pxref{File Variables}). You do
|
||
this by defining a value for the ``variable'' named @code{coding}.
|
||
Emacs does not really have a variable @code{coding}; instead of
|
||
setting a variable, this uses the specified coding system for the
|
||
file. For example, @w{@samp{-*-mode: C; coding: latin-1; -*-}} specifies
|
||
use of the Latin-1 coding system, as well as C mode. When you specify
|
||
the coding explicitly in the file, that overrides
|
||
@code{file-coding-system-alist}.
|
||
|
||
@node Output Coding
|
||
@section Choosing Coding Systems for Output
|
||
|
||
@vindex buffer-file-coding-system
|
||
Once Emacs has chosen a coding system for a buffer, it stores that
|
||
coding system in @code{buffer-file-coding-system}. That makes it the
|
||
default for operations that write from this buffer into a file, such
|
||
as @code{save-buffer} and @code{write-region}. You can specify a
|
||
different coding system for further file output from the buffer using
|
||
@code{set-buffer-file-coding-system} (@pxref{Text Coding}).
|
||
|
||
You can insert any character Emacs supports into any Emacs buffer,
|
||
but most coding systems can only handle a subset of these characters.
|
||
Therefore, it's possible that the characters you insert cannot be
|
||
encoded with the coding system that will be used to save the buffer.
|
||
For example, you could visit a text file in Polish, encoded in
|
||
@code{iso-8859-2}, and add some Russian words to it. When you save
|
||
that buffer, Emacs cannot use the current value of
|
||
@code{buffer-file-coding-system}, because the characters you added
|
||
cannot be encoded by that coding system.
|
||
|
||
When that happens, Emacs tries the most-preferred coding system (set
|
||
by @kbd{M-x prefer-coding-system} or @kbd{M-x
|
||
set-language-environment}). If that coding system can safely encode
|
||
all of the characters in the buffer, Emacs uses it, and stores its
|
||
value in @code{buffer-file-coding-system}. Otherwise, Emacs displays
|
||
a list of coding systems suitable for encoding the buffer's contents,
|
||
and asks you to choose one of those coding systems.
|
||
|
||
If you insert the unsuitable characters in a mail message, Emacs
|
||
behaves a bit differently. It additionally checks whether the
|
||
@c What determines this?
|
||
most-preferred coding system is recommended for use in MIME messages;
|
||
if not, it informs you of this fact and prompts you for another coding
|
||
system. This is so you won't inadvertently send a message encoded in
|
||
a way that your recipient's mail software will have difficulty
|
||
decoding. (You can still use an unsuitable coding system if you enter
|
||
its name at the prompt.)
|
||
|
||
@c It seems that select-message-coding-system does this.
|
||
@c Both sendmail.el and smptmail.el call it; i.e., smtpmail.el still
|
||
@c obeys sendmail-coding-system.
|
||
@vindex sendmail-coding-system
|
||
When you send a mail message (@pxref{Sending Mail}),
|
||
Emacs has four different ways to determine the coding system to use
|
||
for encoding the message text. It first tries the buffer's own value of
|
||
@code{buffer-file-coding-system}, if that is non-@code{nil}.
|
||
Otherwise, it uses the value of @code{sendmail-coding-system}, if that
|
||
is non-@code{nil}. Thirdly, it uses the value of
|
||
@code{default-sendmail-coding-system}.
|
||
If all of these three values are @code{nil}, Emacs encodes outgoing
|
||
mail using the default coding system for new files (i.e., the
|
||
default value of @code{buffer-file-coding-system}), which is
|
||
controlled by your choice of language environment.
|
||
|
||
@node Text Coding
|
||
@section Specifying a Coding System for File Text
|
||
|
||
In cases where Emacs does not automatically choose the right coding
|
||
system for a file's contents, you can use these commands to specify
|
||
one:
|
||
|
||
@table @kbd
|
||
@item C-x @key{RET} f @var{coding} @key{RET}
|
||
Use coding system @var{coding} to save or revisit the file in
|
||
the current buffer (@code{set-buffer-file-coding-system}).
|
||
|
||
@item C-x @key{RET} c @var{coding} @key{RET}
|
||
Specify coding system @var{coding} for the immediately following
|
||
command (@code{universal-coding-system-argument}).
|
||
|
||
@item C-x @key{RET} r @var{coding} @key{RET}
|
||
Revisit the current file using the coding system @var{coding}
|
||
(@code{revert-buffer-with-coding-system}).
|
||
|
||
@item M-x recode-region @key{RET} @var{right} @key{RET} @var{wrong} @key{RET}
|
||
Convert a region that was decoded using coding system @var{wrong},
|
||
decoding it using coding system @var{right} instead.
|
||
@end table
|
||
|
||
@kindex C-x RET f
|
||
@findex set-buffer-file-coding-system
|
||
The command @kbd{C-x @key{RET} f}
|
||
(@code{set-buffer-file-coding-system}) sets the file coding system for
|
||
the current buffer (i.e., the coding system to use when saving or
|
||
reverting the file). You specify which coding system using the
|
||
minibuffer. You can also invoke this command by clicking with
|
||
@kbd{mouse-3} on the coding system indicator in the mode line
|
||
(@pxref{Mode Line}).
|
||
|
||
If you specify a coding system that cannot handle all the characters
|
||
in the buffer, Emacs will warn you about the troublesome characters,
|
||
and ask you to choose another coding system, when you try to save the
|
||
buffer (@pxref{Output Coding}).
|
||
|
||
@cindex specify end-of-line conversion
|
||
You can also use this command to specify the end-of-line conversion
|
||
(@pxref{Coding Systems, end-of-line conversion}) for encoding the
|
||
current buffer. For example, @kbd{C-x @key{RET} f dos @key{RET}} will
|
||
cause Emacs to save the current buffer's text with DOS-style
|
||
carriage return followed by linefeed line endings.
|
||
|
||
@kindex C-x RET c
|
||
@findex universal-coding-system-argument
|
||
Another way to specify the coding system for a file is when you visit
|
||
the file. First use the command @kbd{C-x @key{RET} c}
|
||
(@code{universal-coding-system-argument}); this command uses the
|
||
minibuffer to read a coding system name. After you exit the minibuffer,
|
||
the specified coding system is used for @emph{the immediately following
|
||
command}.
|
||
|
||
So if the immediately following command is @kbd{C-x C-f}, for example,
|
||
it reads the file using that coding system (and records the coding
|
||
system for when you later save the file). Or if the immediately following
|
||
command is @kbd{C-x C-w}, it writes the file using that coding system.
|
||
When you specify the coding system for saving in this way, instead
|
||
of with @kbd{C-x @key{RET} f}, there is no warning if the buffer
|
||
contains characters that the coding system cannot handle.
|
||
|
||
Other file commands affected by a specified coding system include
|
||
@kbd{C-x i} and @kbd{C-x C-v}, as well as the other-window variants
|
||
of @kbd{C-x C-f}. @kbd{C-x @key{RET} c} also affects commands that
|
||
start subprocesses, including @kbd{M-x shell} (@pxref{Shell}). If the
|
||
immediately following command does not use the coding system, then
|
||
@kbd{C-x @key{RET} c} ultimately has no effect.
|
||
|
||
An easy way to visit a file with no conversion is with the @kbd{M-x
|
||
find-file-literally} command. @xref{Visiting}.
|
||
|
||
The default value of the variable @code{buffer-file-coding-system}
|
||
specifies the choice of coding system to use when you create a new file.
|
||
It applies when you find a new file, and when you create a buffer and
|
||
then save it in a file. Selecting a language environment typically sets
|
||
this variable to a good choice of default coding system for that language
|
||
environment.
|
||
|
||
@kindex C-x RET r
|
||
@findex revert-buffer-with-coding-system
|
||
If you visit a file with a wrong coding system, you can correct this
|
||
with @kbd{C-x @key{RET} r} (@code{revert-buffer-with-coding-system}).
|
||
This visits the current file again, using a coding system you specify.
|
||
|
||
@findex recode-region
|
||
If a piece of text has already been inserted into a buffer using the
|
||
wrong coding system, you can redo the decoding of it using @kbd{M-x
|
||
recode-region}. This prompts you for the proper coding system, then
|
||
for the wrong coding system that was actually used, and does the
|
||
conversion. It first encodes the region using the wrong coding system,
|
||
then decodes it again using the proper coding system.
|
||
|
||
@node Communication Coding
|
||
@section Coding Systems for Interprocess Communication
|
||
|
||
This section explains how to specify coding systems for use
|
||
in communication with other processes.
|
||
|
||
@table @kbd
|
||
@item C-x @key{RET} x @var{coding} @key{RET}
|
||
Use coding system @var{coding} for transferring selections to and from
|
||
other graphical applications (@code{set-selection-coding-system}).
|
||
|
||
@item C-x @key{RET} X @var{coding} @key{RET}
|
||
Use coding system @var{coding} for transferring @emph{one}
|
||
selection---the next one---to or from another graphical application
|
||
(@code{set-next-selection-coding-system}).
|
||
|
||
@item C-x @key{RET} p @var{input-coding} @key{RET} @var{output-coding} @key{RET}
|
||
Use coding systems @var{input-coding} and @var{output-coding} for
|
||
subprocess input and output in the current buffer
|
||
(@code{set-buffer-process-coding-system}).
|
||
@end table
|
||
|
||
@kindex C-x RET x
|
||
@kindex C-x RET X
|
||
@findex set-selection-coding-system
|
||
@findex set-next-selection-coding-system
|
||
The command @kbd{C-x @key{RET} x} (@code{set-selection-coding-system})
|
||
specifies the coding system for sending selected text to other windowing
|
||
applications, and for receiving the text of selections made in other
|
||
applications. This command applies to all subsequent selections, until
|
||
you override it by using the command again. The command @kbd{C-x
|
||
@key{RET} X} (@code{set-next-selection-coding-system}) specifies the
|
||
coding system for the next selection made in Emacs or read by Emacs.
|
||
|
||
@vindex x-select-request-type
|
||
The variable @code{x-select-request-type} specifies the data type to
|
||
request from the X Window System for receiving text selections from
|
||
other applications. If the value is @code{nil} (the default), Emacs
|
||
tries @code{UTF8_STRING} and @code{COMPOUND_TEXT}, in this order, and
|
||
uses various heuristics to choose the more appropriate of the two
|
||
results; if none of these succeed, Emacs falls back on @code{STRING}.
|
||
If the value of @code{x-select-request-type} is one of the symbols
|
||
@code{COMPOUND_TEXT}, @code{UTF8_STRING}, @code{STRING}, or
|
||
@code{TEXT}, Emacs uses only that request type. If the value is a
|
||
list of some of these symbols, Emacs tries only the request types in
|
||
the list, in order, until one of them succeeds, or until the list is
|
||
exhausted.
|
||
|
||
@kindex C-x RET p
|
||
@findex set-buffer-process-coding-system
|
||
The command @kbd{C-x @key{RET} p} (@code{set-buffer-process-coding-system})
|
||
specifies the coding system for input and output to a subprocess. This
|
||
command applies to the current buffer; normally, each subprocess has its
|
||
own buffer, and thus you can use this command to specify translation to
|
||
and from a particular subprocess by giving the command in the
|
||
corresponding buffer.
|
||
|
||
You can also use @kbd{C-x @key{RET} c}
|
||
(@code{universal-coding-system-argument}) just before the command that
|
||
runs or starts a subprocess, to specify the coding system for
|
||
communicating with that subprocess. @xref{Text Coding}.
|
||
|
||
The default for translation of process input and output depends on the
|
||
current language environment.
|
||
|
||
@vindex locale-coding-system
|
||
@cindex decoding non-@acronym{ASCII} keyboard input on X
|
||
The variable @code{locale-coding-system} specifies a coding system
|
||
to use when encoding and decoding system strings such as system error
|
||
messages and @code{format-time-string} formats and time stamps. That
|
||
coding system might also be used for decoding non-@acronym{ASCII}
|
||
keyboard input on the X Window System and will also be used to encode
|
||
text sent to the standard output and error streams in batch mode. You
|
||
should choose a coding system that is compatible with the underlying
|
||
system's text representation, which is normally specified by one of
|
||
the environment variables @env{LC_ALL}, @env{LC_CTYPE}, and
|
||
@env{LANG}. (The first one, in the order specified above, whose value
|
||
is nonempty is the one that determines the text representation.)
|
||
|
||
@node File Name Coding
|
||
@section Coding Systems for File Names
|
||
|
||
@table @kbd
|
||
@item C-x @key{RET} F @var{coding} @key{RET}
|
||
Use coding system @var{coding} for encoding and decoding file
|
||
names (@code{set-file-name-coding-system}).
|
||
@end table
|
||
|
||
@findex set-file-name-coding-system
|
||
@kindex C-x RET F
|
||
@cindex file names with non-@acronym{ASCII} characters
|
||
The command @kbd{C-x @key{RET} F} (@code{set-file-name-coding-system})
|
||
specifies a coding system to use for encoding file @emph{names}. It
|
||
has no effect on reading and writing the @emph{contents} of files.
|
||
|
||
@vindex file-name-coding-system
|
||
In fact, all this command does is set the value of the variable
|
||
@code{file-name-coding-system}. If you set the variable to a coding
|
||
system name (as a Lisp symbol or a string), Emacs encodes file names
|
||
using that coding system for all file operations. This makes it
|
||
possible to use non-@acronym{ASCII} characters in file names---or, at
|
||
least, those non-@acronym{ASCII} characters that the specified coding
|
||
system can encode.
|
||
|
||
If @code{file-name-coding-system} is @code{nil}, Emacs uses a
|
||
default coding system determined by the selected language environment,
|
||
and stored in the @code{default-file-name-coding-system} variable
|
||
(normally UTF-8).
|
||
|
||
@cindex file-name encoding, MS-Windows
|
||
@vindex w32-unicode-filenames
|
||
When Emacs runs on MS-Windows versions that are descendants of the
|
||
NT family (Windows 2000, XP, and all the later versions), the value of
|
||
@code{file-name-coding-system} is largely ignored, as Emacs by default
|
||
uses APIs that allow passing Unicode file names directly. By
|
||
contrast, on Windows 9X, file names are encoded using
|
||
@code{file-name-coding-system}, which should be set to the codepage
|
||
(@pxref{Coding Systems, codepage}) pertinent for the current system
|
||
locale. The value of the variable @code{w32-unicode-filenames}
|
||
controls whether Emacs uses the Unicode APIs when it calls OS
|
||
functions that accept file names. This variable is set by the startup
|
||
code to @code{nil} on Windows 9X, and to @code{t} on newer versions of
|
||
MS-Windows.
|
||
|
||
@strong{Warning:} if you change @code{file-name-coding-system} (or the
|
||
language environment) in the middle of an Emacs session, problems can
|
||
result if you have already visited files whose names were encoded using
|
||
the earlier coding system and cannot be encoded (or are encoded
|
||
differently) under the new coding system. If you try to save one of
|
||
these buffers under the visited file name, saving may use the wrong file
|
||
name, or it may encounter an error. If such a problem happens, use @kbd{C-x
|
||
C-w} to specify a new file name for that buffer.
|
||
|
||
@findex recode-file-name
|
||
If a mistake occurs when encoding a file name, use the command
|
||
@kbd{M-x recode-file-name} to change the file name's coding
|
||
system. This prompts for an existing file name, its old coding
|
||
system, and the coding system to which you wish to convert.
|
||
|
||
@node X Coding
|
||
@section Coding Systems for X Keyboard Input
|
||
@cindex X input method coding systems
|
||
Input methods under the X Window System specify their own coding
|
||
systems that must be used to decode keyboard input. By default, Emacs
|
||
determines the coding system used for each input method automatically
|
||
upon establishing the connection to the input method server, and uses
|
||
that specific coding system to decode keyboard input. However, that
|
||
determination can sometimes fail; in that situation, the locale coding
|
||
system (@pxref{Communication Coding}) is used instead.
|
||
|
||
@cindex X input method coding systems, overriding
|
||
@vindex x-input-coding-system
|
||
If the input method does not correctly announce the coding system it
|
||
uses to encode text, then the coding system used by Emacs to decode
|
||
text from input methods must be manually specified. The value of the
|
||
variable @code{x-input-coding-system}, when set to a symbol, is
|
||
unconditionally used as the coding system used to decode keyboard
|
||
input from input methods.
|
||
|
||
@node Terminal Coding
|
||
@section Coding Systems for Terminal I/O
|
||
|
||
@table @kbd
|
||
@item C-x @key{RET} t @var{coding} @key{RET}
|
||
Use coding system @var{coding} for terminal output
|
||
(@code{set-terminal-coding-system}).
|
||
|
||
@item C-x @key{RET} k @var{coding} @key{RET}
|
||
Use coding system @var{coding} for keyboard input
|
||
(@code{set-keyboard-coding-system}).
|
||
@end table
|
||
|
||
@kindex C-x RET t
|
||
@findex set-terminal-coding-system
|
||
The command @kbd{C-x @key{RET} t} (@code{set-terminal-coding-system})
|
||
specifies the coding system for terminal output. If you specify a
|
||
character code for terminal output, all characters output to the
|
||
terminal are translated into that coding system.
|
||
|
||
This feature is useful for certain character-only terminals built to
|
||
support specific languages or character sets---for example, European
|
||
terminals that support one of the ISO Latin character sets. You need to
|
||
specify the terminal coding system when using multibyte text, so that
|
||
Emacs knows which characters the terminal can actually handle.
|
||
|
||
By default, output to the terminal is not translated at all, unless
|
||
Emacs can deduce the proper coding system from your terminal type or
|
||
your locale specification (@pxref{Language Environments}).
|
||
|
||
@kindex C-x RET k
|
||
@findex set-keyboard-coding-system
|
||
@vindex keyboard-coding-system
|
||
The command @kbd{C-x @key{RET} k} (@code{set-keyboard-coding-system}),
|
||
or the variable @code{keyboard-coding-system}, specifies the coding
|
||
system for keyboard input. Character-code translation of keyboard
|
||
input is useful for terminals with keys that send non-@acronym{ASCII}
|
||
graphic characters---for example, some terminals designed for ISO
|
||
Latin-1 or subsets of it.
|
||
|
||
By default, keyboard input is translated based on your system locale
|
||
setting. If your terminal does not really support the encoding
|
||
implied by your locale (for example, if you find it inserts a
|
||
non-@acronym{ASCII} character if you type @kbd{M-i}), you will need to set
|
||
@code{keyboard-coding-system} to @code{nil} to turn off encoding.
|
||
You can do this by putting
|
||
|
||
@lisp
|
||
(set-keyboard-coding-system nil)
|
||
@end lisp
|
||
|
||
@noindent
|
||
in your init file.
|
||
|
||
@findex w32-set-console-codepage
|
||
Setting @code{keyboard-coding-system} has no effect on MS-Windows,
|
||
except on old Windows 9X systems, in which case the encoding must
|
||
match the current codepage of the MS-Windows console, which can be
|
||
changed by calling @code{w32-set-console-codepage}.
|
||
|
||
There is a similarity between using a coding system translation for
|
||
keyboard input, and using an input method: both define sequences of
|
||
keyboard input that translate into single characters. However, input
|
||
methods are designed to be convenient for interactive use by humans, and
|
||
the sequences that are translated are typically sequences of @acronym{ASCII}
|
||
printing characters. Coding systems typically translate sequences of
|
||
non-graphic characters.
|
||
|
||
@node Fontsets
|
||
@section Fontsets
|
||
@cindex fontsets
|
||
|
||
A font typically defines shapes for a single alphabet or script.
|
||
Therefore, displaying the entire range of scripts that Emacs supports
|
||
requires a collection of many fonts. In Emacs, such a collection is
|
||
called a @dfn{fontset}. A fontset is defined by a list of font specifications,
|
||
each assigned to handle a range of character codes, and may fall back
|
||
on another fontset for characters that are not covered by the fonts
|
||
it specifies.
|
||
|
||
@cindex fonts for various scripts
|
||
@cindex Intlfonts package, installation
|
||
Each fontset has a name, like a font. However, while fonts are
|
||
stored in the system and the available font names are defined by the
|
||
system, fontsets are defined within Emacs itself. Once you have
|
||
defined a fontset, you can use it within Emacs by specifying its name,
|
||
anywhere that you could use a single font. Of course, Emacs fontsets
|
||
can use only the fonts that your system supports. If some characters
|
||
appear on the screen as empty boxes or hex codes, this means that the
|
||
fontset in use for them has no font for those characters. In this
|
||
case, or if the characters are shown, but not as well as you would
|
||
like, you may need to install extra fonts or modify the fontset to use
|
||
specific fonts already installed on your system (see below). Your
|
||
operating system may have optional fonts that you can install; or you
|
||
can install the GNU Intlfonts package, which includes fonts for most
|
||
supported scripts.@footnote{If you run Emacs on X, you may need to
|
||
inform the X server about the location of the newly installed fonts
|
||
with commands such as:
|
||
@c FIXME? I feel like this may be out of date.
|
||
@c E.g., the intlfonts tarfile is ~ 10 years old.
|
||
|
||
@example
|
||
xset fp+ /usr/local/share/emacs/fonts
|
||
xset fp rehash
|
||
@end example
|
||
}
|
||
|
||
Emacs creates three fontsets automatically: the @dfn{standard
|
||
fontset}, the @dfn{startup fontset} and the @dfn{default fontset}.
|
||
@c FIXME? The doc of *standard*-fontset-spec says:
|
||
@c "You have the biggest chance to display international characters
|
||
@c with correct glyphs by using the *standard* fontset." (my emphasis)
|
||
@c See https://lists.gnu.org/r/emacs-devel/2012-04/msg00430.html
|
||
The default fontset is most likely to have fonts for a wide variety of
|
||
non-@acronym{ASCII} characters, and is the default fallback for the
|
||
other two fontsets, and if you set a default font rather than fontset.
|
||
However, it does not specify font family names, so results can be
|
||
somewhat random if you use it directly. You can specify a particular
|
||
fontset by starting Emacs with the @samp{-fn} option. For example,
|
||
|
||
@example
|
||
emacs -fn fontset-standard
|
||
@end example
|
||
|
||
@noindent
|
||
You can also specify a fontset with the @samp{Font} resource (@pxref{X
|
||
Resources}).
|
||
|
||
If no fontset is specified for use, then Emacs uses an
|
||
@acronym{ASCII} font, with @samp{fontset-default} as a fallback for
|
||
characters the font does not cover. The standard fontset is only used if
|
||
explicitly requested, despite its name.
|
||
|
||
@findex describe-fontset
|
||
To show the information about a specific fontset, use the
|
||
@w{@kbd{M-x describe-fontset}} command. It prompts for a fontset
|
||
name, defaulting to the one used by the current frame, and then
|
||
displays all the subranges of characters and the fonts assigned to
|
||
them in that fontset. To see which fonts Emacs is using in a session
|
||
started without a specific fontset (which is what happens normally),
|
||
type @kbd{fontset-default @key{RET}} at the prompt, or just
|
||
@kbd{@key{RET}} to describe the fontset used by the current frame.
|
||
|
||
A fontset does not necessarily specify a font for every character
|
||
code. If a fontset specifies no font for a certain character, or if
|
||
it specifies a font that does not exist on your system, then it cannot
|
||
display that character properly. It will display that character as a
|
||
hex code or thin space or an empty box instead. (@xref{Text Display,
|
||
, glyphless characters}, for details.) Or a fontset might specify a
|
||
font for some range of characters, but you may not like their visual
|
||
appearance. If this happens, you may wish to modify your fontset; see
|
||
@ref{Modifying Fontsets}, for how to do that.
|
||
|
||
@node Defining Fontsets
|
||
@section Defining Fontsets
|
||
|
||
@vindex standard-fontset-spec
|
||
@vindex w32-standard-fontset-spec
|
||
@vindex ns-standard-fontset-spec
|
||
@cindex standard fontset
|
||
When running on X, Emacs creates a standard fontset automatically according to the value
|
||
of @code{standard-fontset-spec}. This fontset's name is
|
||
|
||
@example
|
||
-*-fixed-medium-r-normal-*-16-*-*-*-*-*-fontset-standard
|
||
@end example
|
||
|
||
@noindent
|
||
or just @samp{fontset-standard} for short.
|
||
|
||
On GNUstep and macOS, the standard fontset is created using the value of
|
||
@code{ns-standard-fontset-spec}, and on MS Windows it is
|
||
created using the value of @code{w32-standard-fontset-spec}.
|
||
|
||
@c FIXME? How does one access these, or do anything with them?
|
||
@c Does it matter?
|
||
Bold, italic, and bold-italic variants of the standard fontset are
|
||
created automatically. Their names have @samp{bold} instead of
|
||
@samp{medium}, or @samp{i} instead of @samp{r}, or both.
|
||
|
||
@cindex startup fontset
|
||
Emacs generates a fontset automatically, based on any default
|
||
@acronym{ASCII} font that you specify with the @samp{Font} resource or
|
||
the @samp{-fn} argument, or the default font that Emacs found when it
|
||
started. This is the @dfn{startup fontset} and its name is
|
||
@code{fontset-startup}. Emacs generates this fontset by replacing the
|
||
@var{charset_registry} field with @samp{fontset}, and replacing the
|
||
@var{charset_encoding} field with @samp{startup}, then using the
|
||
resulting string to specify a fontset.
|
||
|
||
For instance, if you start Emacs with a font of this form,
|
||
|
||
@c FIXME? I think this is a little misleading, because you cannot (?)
|
||
@c actually specify a font with wildcards, it has to be a complete spec.
|
||
@c Also, an X font specification of this form hasn't (?) been
|
||
@c mentioned before now, and is somewhat obsolete these days.
|
||
@c People are more likely to use a form like
|
||
@c emacs -fn "DejaVu Sans Mono-12"
|
||
@c How does any of this apply in that case?
|
||
@example
|
||
emacs -fn "*courier-medium-r-normal--14-140-*-iso8859-1"
|
||
@end example
|
||
|
||
@noindent
|
||
Emacs generates the following fontset and uses it for the initial X
|
||
window frame:
|
||
|
||
@example
|
||
-*-courier-medium-r-normal-*-14-140-*-*-*-*-fontset-startup
|
||
@end example
|
||
|
||
The startup fontset will use the font that you specify, or a variant
|
||
with a different registry and encoding, for all the characters that
|
||
are supported by that font, and fallback on @samp{fontset-default} for
|
||
other characters.
|
||
|
||
With the X resource @samp{Emacs.Font}, you can specify a fontset name
|
||
just like an actual font name. But be careful not to specify a fontset
|
||
name in a wildcard resource like @samp{Emacs*Font}---that wildcard
|
||
specification matches various other resources, such as for menus, and
|
||
@c FIXME is this still true?
|
||
menus cannot handle fontsets. @xref{X Resources}.
|
||
|
||
You can specify additional fontsets using X resources named
|
||
@samp{Fontset-@var{n}}, where @var{n} is an integer starting from 0.
|
||
The resource value should have this form:
|
||
|
||
@smallexample
|
||
@var{fontpattern}, @r{[}@var{charset}:@var{font}@r{]@dots{}}
|
||
@end smallexample
|
||
|
||
@noindent
|
||
where @var{fontpattern} should have the form of a standard X font name
|
||
(see the previous fontset-startup example), except for the last two
|
||
fields. They should have the form @samp{fontset-@var{alias}}.
|
||
|
||
Each fontset has two names, one long and one short. The long name
|
||
is @var{fontpattern}. The short name is @samp{fontset-@var{alias}},
|
||
the last 2 fields of the long name (e.g., @samp{fontset-startup} for
|
||
the fontset automatically created at startup). You can refer to the
|
||
fontset by either name.
|
||
|
||
The construct @samp{@var{charset}:@var{font}} specifies which font to
|
||
use (in this fontset) for one particular character set. Here,
|
||
@var{charset} is the name of a character set, and @var{font} is the
|
||
font to use for that character set. You can use this construct any
|
||
number of times in defining one fontset.
|
||
|
||
For the other character sets, Emacs chooses a font based on
|
||
@var{fontpattern}. It replaces @samp{fontset-@var{alias}} with values
|
||
that describe the character set. For the @acronym{ASCII} character font,
|
||
@samp{fontset-@var{alias}} is replaced with @samp{ISO8859-1}.
|
||
|
||
In addition, when several consecutive fields are wildcards, Emacs
|
||
collapses them into a single wildcard. This is to prevent use of
|
||
auto-scaled fonts. Fonts made by scaling larger fonts are not usable
|
||
for editing, and scaling a smaller font is also not useful, because it is
|
||
better to use the smaller font in its own size, which is what Emacs
|
||
does.
|
||
|
||
Thus if @var{fontpattern} is this,
|
||
|
||
@example
|
||
-*-fixed-medium-r-normal-*-24-*-*-*-*-*-fontset-24
|
||
@end example
|
||
|
||
@noindent
|
||
the font specification for @acronym{ASCII} characters would be this:
|
||
|
||
@example
|
||
-*-fixed-medium-r-normal-*-24-*-ISO8859-1
|
||
@end example
|
||
|
||
@noindent
|
||
and the font specification for Chinese GB2312 characters would be this:
|
||
|
||
@example
|
||
-*-fixed-medium-r-normal-*-24-*-gb2312*-*
|
||
@end example
|
||
|
||
You may not have any Chinese font matching the above font
|
||
specification. Most X distributions include only Chinese fonts that
|
||
have @samp{song ti} or @samp{fangsong ti} in the @var{family} field. In
|
||
such a case, @samp{Fontset-@var{n}} can be specified as:
|
||
|
||
@smallexample
|
||
Emacs.Fontset-0: -*-fixed-medium-r-normal-*-24-*-*-*-*-*-fontset-24,\
|
||
chinese-gb2312:-*-*-medium-r-normal-*-24-*-gb2312*-*
|
||
@end smallexample
|
||
|
||
@noindent
|
||
Then, the font specifications for all but Chinese GB2312 characters have
|
||
@samp{fixed} in the @var{family} field, and the font specification for
|
||
Chinese GB2312 characters has a wild card @samp{*} in the @var{family}
|
||
field.
|
||
|
||
@findex create-fontset-from-fontset-spec
|
||
The function that processes the fontset resource value to create the
|
||
fontset is called @code{create-fontset-from-fontset-spec}. You can also
|
||
call this function explicitly to create a fontset.
|
||
|
||
@xref{Fonts}, for more information about font naming.
|
||
|
||
@node Modifying Fontsets
|
||
@section Modifying Fontsets
|
||
@cindex fontsets, modifying
|
||
@findex set-fontset-font
|
||
|
||
Fontsets do not always have to be created from scratch. If only
|
||
minor changes are required it may be easier to modify an existing
|
||
fontset, usually @samp{fontset-default}. Modifying
|
||
@samp{fontset-default} will also affect other fontsets that use it as
|
||
a fallback, so can be an effective way of fixing problems with the
|
||
fonts that Emacs chooses for a particular script.
|
||
|
||
Fontsets can be modified using the function @code{set-fontset-font},
|
||
specifying a character, a charset, a script, or a range of characters
|
||
to modify the font for, and a font specification for the font to be
|
||
used. Some examples are:
|
||
|
||
@example
|
||
;; Prefer a big5 font for han characters.
|
||
(set-fontset-font "fontset-default"
|
||
'han (font-spec :registry "big5")
|
||
nil 'prepend)
|
||
|
||
;; Use MyPrivateFont for the Unicode private use area.
|
||
(set-fontset-font "fontset-default" '(#xe000 . #xf8ff)
|
||
"MyPrivateFont")
|
||
|
||
;; Use Liberation Mono for latin-3 charset.
|
||
(set-fontset-font "fontset-default" 'iso-8859-3
|
||
"Liberation Mono")
|
||
|
||
;; Use DejaVu Sans Mono as a fallback in fontset-startup
|
||
;; before resorting to fontset-default.
|
||
(set-fontset-font "fontset-startup" nil "DejaVu Sans Mono"
|
||
nil 'append)
|
||
@end example
|
||
|
||
When modifying the fontset for the @code{symbol} script, the value of
|
||
@code{use-default-font-for-symbols} will affect whether the fontset is
|
||
actually used.
|
||
|
||
@noindent
|
||
@xref{Fontsets, , , elisp, GNU Emacs Lisp Reference Manual}, for more
|
||
details about using the @code{set-fontset-font} function.
|
||
|
||
@cindex script of a character
|
||
@cindex codepoint of a character
|
||
If you don't know the character's codepoint or the script to which it
|
||
belongs, you can ask Emacs. With point at the character, type
|
||
@w{@kbd{C-u C-x =}} (@code{what-cursor-position}), and this
|
||
information, together with much more, will be displayed in the
|
||
@file{*Help*} buffer that Emacs pops up. @xref{Position Info}. For
|
||
example, Japanese characters belong to the @samp{kana} script, but
|
||
Japanese text also mixes them with Chinese characters so the following
|
||
uses the @samp{han} script to set up Emacs to use the @samp{Kochi
|
||
Gothic} font for Japanese text:
|
||
|
||
@example
|
||
(set-fontset-font "fontset-default" 'han "Kochi Gothic")
|
||
@end example
|
||
|
||
@noindent
|
||
@cindex CKJ characters
|
||
(For convenience, the @samp{han} script in Emacs is set up to support
|
||
all of the Chinese, Japanese, and Korean, a.k.a.@: @acronym{CJK},
|
||
characters, not just Chinese characters.)
|
||
|
||
@vindex script-representative-chars
|
||
For the list of known scripts, see the variable
|
||
@code{script-representative-chars}.
|
||
|
||
Fontset settings like those above only affect characters that the
|
||
default font doesn't support, so if the @samp{Kochi Gothic} font
|
||
covers Latin characters, it will not be used for displaying Latin
|
||
scripts, since the default font used by Emacs usually covers Basic
|
||
Latin.
|
||
|
||
@cindex ignore font
|
||
@cindex fonts, how to ignore
|
||
@vindex face-ignored-fonts
|
||
Some fonts installed on your system might be broken, or produce
|
||
unpleasant results for characters for which they are used, and you may
|
||
wish to instruct Emacs to completely ignore them while searching for a
|
||
suitable font required to display a character. You can do that by
|
||
adding the offending fonts to the value of the variable
|
||
@code{face-ignored-fonts}, which is a list. Here's an example to put
|
||
in your @file{~/.emacs}:
|
||
|
||
@example
|
||
(add-to-list 'face-ignored-fonts "Some Bad Font")
|
||
@end example
|
||
|
||
@node Undisplayable Characters
|
||
@section Undisplayable Characters
|
||
|
||
There may be some non-@acronym{ASCII} characters that your
|
||
terminal cannot display. Most text terminals support just a single
|
||
character set (use the variable @code{default-terminal-coding-system}
|
||
to tell Emacs which one, @ref{Terminal Coding}); characters that
|
||
can't be encoded in that coding system are displayed as @samp{?} by
|
||
default.
|
||
|
||
Graphical displays can display a broader range of characters, but
|
||
you may not have fonts installed for all of them; characters that have
|
||
no font appear as a hollow box.
|
||
|
||
If you use Latin-1 characters but your terminal can't display
|
||
Latin-1, you can arrange to display mnemonic @acronym{ASCII} sequences
|
||
instead, e.g., @samp{"o} for o-umlaut. Load the library
|
||
@file{iso-ascii} to do this.
|
||
|
||
@vindex latin1-display
|
||
If your terminal can display Latin-1, you can display characters
|
||
from other European character sets using a mixture of equivalent
|
||
Latin-1 characters and @acronym{ASCII} mnemonics. Customize the variable
|
||
@code{latin1-display} to enable this. The mnemonic @acronym{ASCII}
|
||
sequences mostly correspond to those of the prefix input methods.
|
||
|
||
@node Unibyte Mode
|
||
@section Unibyte Editing Mode
|
||
|
||
@cindex European character sets
|
||
@cindex accented characters
|
||
@cindex ISO Latin character sets
|
||
@cindex Unibyte operation
|
||
The ISO 8859 Latin-@var{n} character sets define character codes in
|
||
the range 0240 to 0377 octal (160 to 255 decimal) to handle the
|
||
accented letters and punctuation needed by various European languages
|
||
(and some non-European ones). Note that Emacs considers bytes with
|
||
codes in this range as raw bytes, not as characters, even in a unibyte
|
||
buffer, i.e., if you disable multibyte characters. However, Emacs can
|
||
still handle these character codes as if they belonged to @emph{one}
|
||
of the single-byte character sets at a time. To specify @emph{which}
|
||
of these codes to use, invoke @kbd{M-x set-language-environment} and
|
||
specify a suitable language environment such as @samp{Latin-@var{n}}.
|
||
@xref{Disabling Multibyte, , Disabling Multibyte Characters, elisp,
|
||
GNU Emacs Lisp Reference Manual}.
|
||
|
||
@vindex unibyte-display-via-language-environment
|
||
Emacs can also display bytes in the range 160 to 255 as readable
|
||
characters, provided the terminal or font in use supports them. This
|
||
works automatically. On a graphical display, Emacs can also display
|
||
single-byte characters through fontsets, in effect by displaying the
|
||
equivalent multibyte characters according to the current language
|
||
environment. To request this, set the variable
|
||
@code{unibyte-display-via-language-environment} to a non-@code{nil}
|
||
value. Note that setting this only affects how these bytes are
|
||
displayed, but does not change the fundamental fact that Emacs treats
|
||
them as raw bytes, not as characters.
|
||
|
||
@cindex @code{iso-ascii} library
|
||
If your terminal does not support display of the Latin-1 character
|
||
set, Emacs can display these characters as @acronym{ASCII} sequences which at
|
||
least give you a clear idea of what the characters are. To do this,
|
||
load the library @code{iso-ascii}. Similar libraries for other
|
||
Latin-@var{n} character sets could be implemented, but have not been
|
||
so far.
|
||
|
||
@findex standard-display-8bit
|
||
@cindex 8-bit display
|
||
Normally non-ISO-8859 characters (decimal codes between 128 and 159
|
||
inclusive) are displayed as octal escapes. You can change this for
|
||
non-standard extended versions of ISO-8859 character sets by using the
|
||
function @code{standard-display-8bit} in the @code{disp-table} library.
|
||
|
||
There are two ways to input single-byte non-@acronym{ASCII}
|
||
characters:
|
||
|
||
@itemize @bullet
|
||
@cindex 8-bit input
|
||
@item
|
||
You can use an input method for the selected language environment.
|
||
@xref{Input Methods}. When you use an input method in a unibyte
|
||
buffer, the non-@acronym{ASCII} character you specify with it is
|
||
converted to unibyte.
|
||
|
||
@item
|
||
If your keyboard can generate character codes 128 (decimal) and up,
|
||
representing non-@acronym{ASCII} characters, you can type those
|
||
character codes directly.
|
||
|
||
On a graphical display, you should not need to do anything special to
|
||
use these keys; they should simply work. On a text terminal, you
|
||
should use the command @kbd{M-x set-keyboard-coding-system} or
|
||
customize the variable @code{keyboard-coding-system} to specify which
|
||
coding system your keyboard uses (@pxref{Terminal Coding}). Enabling
|
||
this feature will probably require you to use @key{ESC} to type Meta
|
||
characters; however, on a console terminal or a terminal emulator such
|
||
as @code{xterm}, you can arrange for Meta to be converted to @key{ESC}
|
||
and still be able to type 8-bit characters present directly on the
|
||
keyboard or using @key{Compose} or @key{AltGr} keys. @xref{User Input}.
|
||
|
||
@cindex input methods, native
|
||
@cindex XIM, X Input Methods
|
||
@cindex GTK input methods
|
||
Many modern systems provide @dfn{native input methods} for many
|
||
languages whose characters don't have keyboard keys assigned to them.
|
||
If Emacs was built with support for these native input methods, you
|
||
can activate such an input method and type the characters they
|
||
support. How to activate and use these input methods depends on the
|
||
system and the input method, and will not be described here; see your
|
||
system documentation. Here we describe some Emacs facilities to
|
||
control the use of the native input methods.
|
||
|
||
@vindex x-gtk-use-native-input
|
||
In Emacs built with the GTK toolkit, the variable
|
||
@code{x-gtk-use-native-input} controls whether Emacs should receive
|
||
characters produced by GTK input methods. If the value is @code{nil},
|
||
the default, Emacs uses the X input methods (@acronym{XIM}), otherwise
|
||
it uses the GTK input methods. The @code{useXIM} X resource controls
|
||
whether to use @acronym{XIM}, and @code{inputStyle} X resource
|
||
controls the display on X of preview text generated by the native
|
||
input methods; @pxref{Table of Resources}.
|
||
|
||
On MS-Windows, Emacs supports native inputs methods provided by
|
||
@acronym{IMM}, the Input Method Manager, but that can be turned off if
|
||
needed; @pxref{Windows Keyboard}.
|
||
|
||
@cindex @code{iso-transl} library
|
||
@cindex compose character
|
||
@cindex dead character
|
||
@item
|
||
You can use the key @kbd{C-x 8} as a compose-character prefix for
|
||
entry of non-@acronym{ASCII} Latin-1 and other printing
|
||
characters. @kbd{C-x 8} is good for insertion (in the minibuffer as
|
||
well as other buffers), for searching, and in any other context where
|
||
a key sequence is allowed.
|
||
|
||
@kbd{C-x 8} works by loading the @code{iso-transl} library. Once that
|
||
library is loaded, the @key{Alt} modifier key, if the keyboard has
|
||
one, serves the same purpose as @kbd{C-x 8}: use @key{Alt} together
|
||
with an accent character to modify the following letter. In addition,
|
||
if the keyboard has keys for the Latin-1 dead accent characters,
|
||
they too are defined to compose with the following character, once
|
||
@code{iso-transl} is loaded.
|
||
|
||
Use @kbd{C-x 8 C-h} to list all the available @kbd{C-x 8} translations.
|
||
|
||
The set of translations available can be extended with certain
|
||
language-specific characters using the @kbd{M-x iso-transl-set-language}
|
||
command. Current supported languages are: @samp{French}, @samp{German},
|
||
@samp{Portuguese}, @samp{Spanish}, and @samp{Esperanto}. See
|
||
@code{iso-transl-language-alist} for details.
|
||
@end itemize
|
||
|
||
@node Charsets
|
||
@section Charsets
|
||
@cindex charsets
|
||
|
||
In Emacs, @dfn{charset} is short for ``character set''. Emacs
|
||
supports most popular charsets (such as @code{ascii},
|
||
@code{iso-8859-1}, @code{cp1250}, @code{big5}, and @code{unicode}), in
|
||
addition to some charsets of its own (such as @code{emacs},
|
||
@code{unicode-bmp}, and @code{eight-bit}). All supported characters
|
||
belong to one or more charsets.
|
||
|
||
Emacs normally does the right thing with respect to charsets, so
|
||
that you don't have to worry about them. However, it is sometimes
|
||
helpful to know some of the underlying details about charsets.
|
||
|
||
One example is font selection (@pxref{Fonts}). Each language
|
||
environment (@pxref{Language Environments}) defines a priority
|
||
list for the various charsets. When searching for a font, Emacs
|
||
initially attempts to find one that can display the highest-priority
|
||
charsets. For instance, in the Japanese language environment, the
|
||
charset @code{japanese-jisx0208} has the highest priority, so Emacs
|
||
tries to use a font whose @code{registry} property is
|
||
@samp{JISX0208.1983-0}.
|
||
|
||
@findex list-charset-chars
|
||
@cindex characters in a certain charset
|
||
@findex describe-character-set
|
||
There are two commands that can be used to obtain information about
|
||
charsets. The command @kbd{M-x list-charset-chars} prompts for a
|
||
charset name, and displays all the characters in that character set.
|
||
The command @kbd{M-x describe-character-set} prompts for a charset
|
||
name, and displays information about that charset, including its
|
||
internal representation within Emacs.
|
||
|
||
@findex list-character-sets
|
||
@kbd{M-x list-character-sets} displays a list of all supported
|
||
charsets. The list gives the names of charsets and additional
|
||
information to identity each charset; for more details, see the
|
||
@url{https://www.itscj.ipsj.or.jp/itscj_english/iso-ir/ISO-IR.pdf,
|
||
ISO International Register of Coded Character Sets to be Used with
|
||
Escape Sequences (ISO-IR)} maintained by
|
||
the @url{https://www.itscj.ipsj.or.jp/itscj_english/,
|
||
Information Processing Society of Japan/Information Technology
|
||
Standards Commission of Japan (IPSJ/ITSCJ)}. In this list,
|
||
charsets are divided into two categories: @dfn{normal charsets} are
|
||
listed first, followed by @dfn{supplementary charsets}. A
|
||
supplementary charset is one that is used to define another charset
|
||
(as a parent or a subset), or to provide backward-compatibility for
|
||
older Emacs versions.
|
||
|
||
To find out which charset a character in the buffer belongs to, put
|
||
point before it and type @kbd{C-u C-x =} (@pxref{International
|
||
Chars}).
|
||
|
||
@node Bidirectional Editing
|
||
@section Bidirectional Editing
|
||
@cindex bidirectional editing
|
||
@cindex right-to-left text
|
||
|
||
Emacs supports editing text written in scripts, such as Arabic,
|
||
Farsi, and Hebrew, whose natural ordering of horizontal text for
|
||
display is from right to left. However, digits and Latin text
|
||
embedded in these scripts are still displayed left to right. It is
|
||
also not uncommon to have small portions of text in Arabic or Hebrew
|
||
embedded in an otherwise Latin document; e.g., as comments and strings
|
||
in a program source file. For these reasons, text that uses these
|
||
scripts is actually @dfn{bidirectional}: a mixture of runs of
|
||
left-to-right and right-to-left characters.
|
||
|
||
This section describes the facilities and options provided by Emacs
|
||
for editing bidirectional text.
|
||
|
||
@cindex logical order
|
||
@cindex visual order
|
||
Emacs stores right-to-left and bidirectional text in the so-called
|
||
@dfn{logical} (or @dfn{reading}) order: the buffer or string position
|
||
of the first character you read precedes that of the next character.
|
||
Reordering of bidirectional text into the @dfn{visual} order happens
|
||
at display time. As a result, character positions no longer increase
|
||
monotonically with their positions on display. Emacs implements the
|
||
Unicode Bidirectional Algorithm (UBA) described in the
|
||
@uref{https://unicode.org/reports/tr9/, Unicode Standard Annex #9}, for
|
||
reordering of bidirectional text for display.
|
||
It deviates from the UBA only in how continuation lines are displayed
|
||
when text direction is opposite to the base paragraph direction,
|
||
e.g., when a long line of English text appears in a right-to-left
|
||
paragraph.
|
||
|
||
@vindex bidi-display-reordering
|
||
The buffer-local variable @code{bidi-display-reordering} controls
|
||
whether text in the buffer is reordered for display. If its value is
|
||
non-@code{nil}, Emacs reorders characters that have right-to-left
|
||
directionality when they are displayed. The default value is
|
||
@code{t}.
|
||
|
||
@cindex base direction of paragraphs
|
||
@cindex paragraph, base direction
|
||
@vindex bidi-paragraph-start-re
|
||
@vindex bidi-paragraph-separate-re
|
||
Each paragraph of bidirectional text can have its own @dfn{base
|
||
direction}, either right-to-left or left-to-right. Text in
|
||
left-to-right paragraphs begins on the screen at the left margin of
|
||
the window and is truncated or continued when it reaches the right
|
||
margin. By contrast, text in right-to-left paragraphs is displayed
|
||
starting at the right margin and is continued or truncated at the left
|
||
margin. By default, paragraph boundaries are empty lines, i.e., lines
|
||
consisting entirely of whitespace characters. To change that, you can
|
||
customize the two variables @code{bidi-paragraph-start-re} and
|
||
@code{bidi-paragraph-separate-re}, whose values should be regular
|
||
expressions (strings); e.g., to have a single newline start a new
|
||
paragraph, set both of these variables to @code{"^"}. These two
|
||
variables are buffer-local (@pxref{Locals}).
|
||
|
||
@vindex bidi-paragraph-direction
|
||
Emacs determines the base direction of each paragraph dynamically,
|
||
based on the text at the beginning of the paragraph. However,
|
||
sometimes a buffer may need to force a certain base direction for its
|
||
paragraphs. The variable @code{bidi-paragraph-direction}, if
|
||
non-@code{nil}, disables the dynamic determination of the base
|
||
direction, and instead forces all paragraphs in the buffer to have the
|
||
direction specified by its buffer-local value. The value can be either
|
||
@code{right-to-left} or @code{left-to-right}. Any other value is
|
||
interpreted as @code{nil}.
|
||
|
||
@cindex LRM
|
||
@cindex RLM
|
||
Alternatively, you can control the base direction of a paragraph by
|
||
inserting special formatting characters in front of the paragraph.
|
||
The special character @code{RIGHT-TO-LEFT MARK}, or @sc{rlm}, forces
|
||
the right-to-left direction on the following paragraph, while
|
||
@code{LEFT-TO-RIGHT MARK}, or @sc{lrm} forces the left-to-right
|
||
direction. (You can use @kbd{C-x 8 @key{RET}} to insert these characters.)
|
||
In a GUI session, the @sc{lrm} and @sc{rlm} characters display as very
|
||
thin blank characters; on text terminals they display as blanks.
|
||
|
||
Because characters are reordered for display, Emacs commands that
|
||
operate in the logical order or on stretches of buffer positions may
|
||
produce unusual effects. For example, the commands @kbd{C-f} and
|
||
@kbd{C-b} move point in the logical order, so the cursor will
|
||
sometimes jump when point traverses reordered bidirectional text.
|
||
Similarly, a highlighted region covering a contiguous range of
|
||
character positions may look discontinuous if the region spans
|
||
reordered text. This is normal and similar to the behavior of other
|
||
programs that support bidirectional text.
|
||
|
||
@kindex RIGHT@r{, and bidirectional text}
|
||
@kindex LEFT@r{, and bidirectional text}
|
||
@findex right-char@r{, and bidirectional text}
|
||
@findex left-char@r{, and bidirectional text}
|
||
Cursor motion commands bound to arrow keys, such as @key{LEFT} and
|
||
@kbd{C-@key{RIGHT}}, are sensitive to the base direction of the
|
||
current paragraph. In a left-to-right paragraph, commands bound to
|
||
@key{RIGHT} with or without modifiers move @emph{forward} through
|
||
buffer text, but in a right-to-left paragraph they move
|
||
@emph{backward} instead. This reflects the fact that in a
|
||
right-to-left paragraph buffer positions predominantly increase when
|
||
moving to the left on display.
|
||
|
||
When you move out of a paragraph, the meaning of the arrow keys
|
||
might change if the base direction of the preceding or the following
|
||
paragraph is different from the paragraph out of which you moved.
|
||
When that happens, you need to adjust the arrow key you press to the
|
||
new base direction.
|
||
|
||
@vindex visual-order-cursor-movement
|
||
@cindex cursor, visual-order motion
|
||
By default, @key{LEFT} and @key{RIGHT} move in the logical order,
|
||
but if @code{visual-order-cursor-movement} is non-@code{nil}, these
|
||
commands move to the character that is, correspondingly, to the left
|
||
or right of the current screen position, moving to the next or
|
||
previous screen line as appropriate. Note that this might potentially
|
||
move point many buffer positions away, depending on the surrounding
|
||
bidirectional context.
|
||
|
||
@cindex bidi formatting control characters
|
||
Bidirectional text sometimes uses special formatting characters to
|
||
affect the reordering of text for display. The @sc{lrm} and @sc{rlm}
|
||
characters, mentioned above, are two such characters, but there are
|
||
more of them. They are by default displayed as thin space glyphs on
|
||
GUI frames, and as simple spaces on text-mode frames. If you want to
|
||
be aware of these special control characters, so that their effect on
|
||
display does not come as a surprise, you can turn on the
|
||
@code{glyphless-display-mode} (@pxref{Text Display}). This minor mode
|
||
will cause these formatting characters to be displayed as acronyms
|
||
inside a small box, so that they stand out on display, and make their
|
||
effect easier to understand.
|