Internalization in GNU emacs

The figure below illustrates 3 useful tricks.

• After setting Language Environment to "Chinese-GB", the effect for some of the other commands changes. In particular, the default of M-x set-input-method changes from nothing (no default), to chinese-py-punct.
• M-x describ-char goes into split-screen, and showing information about the current character at the cursor position, how to input it in the current input method, what font is being used to display it, etc.
• It is possible to tell emacs, after a file opened and the content looking wrong, to tell it to "Revisit this file immediately using specified coding system".

General tips:

• C-x \ to toggle current input method and ascii.
• You select the one you mean using keys such as C-f (forward), C-b (backward), C-n (next line), C-p (previous line) (or the arrow keys), and digits, C-SPC for current position . C-x 8 RET (M-x insert-char) prompts raw code points in hex.
• C-x 1 to go back to single screen.
• C-x o to switch to other screen.

There are three ways of telling emacs that the current file is in, for example, GB2312 encoding:

• LANG=zh_CN.GB2312 emacs ... at launch
• -*- coding: gb2312 -*- as part of the first line of the file, or equivalent at the end of file (see Chapter 33, Customization, Local Variables in files, Specifying File Variables):

/* Local Variables: */
/* coding: gb2312   */
/* End:             */

• It is possible to set Emacs Directory Variables for whole set of files in a directory.

• "Set Language Environment" and "Set Coding Systems" (both), as above.

Cut and Paste with other applications: Emacs is clever enough and treats by default everything from X11 (as x-select-request-type) in the order UTF8_STRING, COMPOUND_TEXT, STRING, regardless and independent of the current file buffer content.

Various useful things under M-x

• describe-key and press a key

• describe-char describe the character under the cursor.

• (global-set-key [kp-5] 'goto-line) to bind keypad-5 to goto-line.

• It is not a good idea to rebind ESC (Meta and \C-[), see description of meta-prefix-char and Meta-Character Syntax, or \C-h, or \C-i quirk. Ordinary text terminals have no way of generating non-ASCII control characters.. Other Character Modifier Bits, Basic Char Syntax

EDT bugs

• #50364 27.2; EDT mode Xmodmap related documentation needs updating

• edt-mapper: When numlock is on, keypad keys are alias'ed to [deletechar], '[up]', etc. TPU mapper generates [kp-delete], [kp-up], etc.

Latest Manuals:

• GNU emacs 27, pdf
• Emacs quick reference Card, pdf
• EDT emulation, html

Subset (hosted and copied here): Emacs Chapter 19, pdf, Emacs Lisp reference, Chapter 33, pdf, EDT emulation, pdf. Also Annnotated sample xmodmap file for re-mapping the Num_Lock as GOLD key.

Reference: Intro to emacs Lisp Programming and Emacs Lisp Reference

Emacs FAQ contains a whole sections on key bindings.

Built-in Help:

Old Versions

Package emacs25 is available on Ubuntu bionic (18.04LTS).

Older versions are under current, emacs21, emacs22, emacs23, emacs24, emacs25.

Some older packaging is missing dfsg-compliance.

Historical

Variable default-enable-multibyte-characters is obsolete since 23.2. The variable enable-multibyte-characters is buffer-local, and cannot be set directly, but only via the function set-buffer-multibyte.

Changes in Emacs 23.2:

*** Unibyte sessions are now considered obsolete.
This refers to the EMACS_UNIBYTE environment variable as well as the
--unibyte, --multibyte, --no-multibyte, and --no-unibyte command line
arguments.  Customizing enable-multibyte-characters and setting
default-enable-multibyte-characters are also deprecated.