This is Info file ../../info/xemacs.info, produced by Makeinfo version 1.68 from the input file xemacs.texi. INFO-DIR-SECTION XEmacs Editor START-INFO-DIR-ENTRY * XEmacs: (xemacs). XEmacs Editor. END-INFO-DIR-ENTRY This file documents the XEmacs editor. Copyright (C) 1985, 1986, 1988 Richard M. Stallman. Copyright (C) 1991, 1992, 1993, 1994 Lucid, Inc. Copyright (C) 1993, 1994 Sun Microsystems, Inc. Copyright (C) 1995 Amdahl Corporation. Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided also that the sections entitled "The GNU Manifesto", "Distribution" and "GNU General Public License" are included exactly as in the original, and provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Permission is granted to copy and distribute translations of this manual into another language, under the above conditions for modified versions, except that the sections entitled "The GNU Manifesto", "Distribution" and "GNU General Public License" may be included in a translation approved by the author instead of in the original English.  File: xemacs.info, Node: Dired Immed, Prev: Dired Deletion, Up: Dired Immediate File Operations in Dired ---------------------------------- Some file operations in Dired take place immediately when they are requested. `C' Copies the file described on the current line. You must supply a file name to copy to, using the minibuffer. `f' Visits the file described on the current line. It is just like typing `C-x C-f' and supplying that file name. If the file on this line is a subdirectory, `f' actually causes Dired to be invoked on that subdirectory. *Note Visiting::. `o' Like `f', but uses another window to display the file's buffer. The Dired buffer remains visible in the first window. This is like using `C-x 4 C-f' to visit the file. *Note Windows::. `R' Renames the file described on the current line. You must supply a file name to rename to, using the minibuffer. `v' Views the file described on this line using `M-x view-file'. Viewing a file is like visiting it, but is slanted toward moving around in the file conveniently and does not allow changing the file. *Note View File: Misc File Ops. Viewing a file that is a directory runs Dired on that directory.  File: xemacs.info, Node: Misc File Ops, Prev: Dired, Up: Files Miscellaneous File Operations ============================= Emacs has commands for performing many other operations on files. All operate on one file; they do not accept wildcard file names. You can use the command `M-x add-name-to-file' to add a name to an existing file without removing the old name. The new name must belong on the file system that the file is on. `M-x append-to-file' adds the text of the region to the end of the specified file. `M-x copy-file' reads the file OLD and writes a new file named NEW with the same contents. Confirmation is required if a file named NEW already exists, because copying overwrites the old contents of the file NEW. `M-x delete-file' deletes a specified file, like the `rm' command in the shell. If you are deleting many files in one directory, it may be more convenient to use Dired (*note Dired::.). `M-x insert-file' inserts a copy of the contents of a specified file into the current buffer at point, leaving point unchanged before the contents and the mark after them. *Note Mark::. `M-x make-symbolic-link' reads two file names OLD and LINKNAME, and then creates a symbolic link named LINKNAME and pointing at OLD. Future attempts to open file LINKNAME will then refer to the file named OLD at the time the opening is done, or will result in an error if the name OLD is not in use at that time. Confirmation is required if you create the link while LINKNAME is in use. Note that not all systems support symbolic links. `M-x rename-file' reads two file names OLD and NEW using the minibuffer, then renames file OLD as NEW. If a file named NEW already exists, you must confirm with `yes' or renaming is not done; this is because renaming causes the previous meaning of the name NEW to be lost. If OLD and NEW are on different file systems, the file OLD is copied and deleted. `M-x view-file' allows you to scan or read a file by sequential screenfuls. It reads a file name argument using the minibuffer. After reading the file into an Emacs buffer, `view-file' reads and displays one windowful. You can then type to scroll forward one window, or to scroll backward. Various other commands are provided for moving around in the file, but none for changing it; type `C-h' while viewing a file for a list of them. Most commands are the default Emacs cursor motion commands. To exit from viewing, type `C-c'.  File: xemacs.info, Node: Buffers, Next: Windows, Prev: Files, Up: Top Using Multiple Buffers ********************** Text you are editing in Emacs resides in an object called a "buffer". Each time you visit a file, Emacs creates a buffer to hold the file's text. Each time you invoke Dired, Emacs creates a buffer to hold the directory listing. If you send a message with `C-x m', a buffer named `*mail*' is used to hold the text of the message. When you ask for a command's documentation, it appears in a buffer called `*Help*'. At any time, one and only one buffer is "selected". It is also called the "current buffer". Saying a command operates on "the buffer" really means that the command operates on the selected buffer, as most commands do. When Emacs creates multiple windows, each window has a chosen buffer which is displayed there, but at any time only one of the windows is selected and its chosen buffer is the selected buffer. Each window's mode line displays the name of the buffer the window is displaying (*note Windows::.). Each buffer has a name which can be of any length but is case-sensitive. You can select a buffer using its name. Most buffers are created when you visit files; their names are derived from the files' names. You can also create an empty buffer with any name you want. A newly started Emacs has a buffer named `*scratch*' which you can use for evaluating Lisp expressions in Emacs. Each buffer records what file it is visiting, whether it is modified, and what major mode and minor modes are in effect in it (*note Major Modes::.). Any Emacs variable can be made "local to" a particular buffer, meaning its value in that buffer can be different from the value in other buffers. *Note Locals::. * Menu: * Select Buffer:: Creating a new buffer or reselecting an old one. * List Buffers:: Getting a list of buffers that exist. * Misc Buffer:: Renaming; changing read-onliness; copying text. * Kill Buffer:: Killing buffers you no longer need. * Several Buffers:: How to go through the list of all buffers and operate variously on several of them.  File: xemacs.info, Node: Select Buffer, Next: List Buffers, Prev: Buffers, Up: Buffers Creating and Selecting Buffers ============================== `C-x b BUFFER ' Select or create a buffer named BUFFER (`switch-to-buffer'). `C-x 4 b BUFFER ' Similar, but select a buffer named BUFFER in another window (`switch-to-buffer-other-window'). `M-x switch-to-other-buffer N' Switch to the previous buffer. To select a buffer named BUFNAME, type `C-x b BUFNAME '. This is the command `switch-to-buffer' with argument BUFNAME. You can use completion on an abbreviation for the buffer name you want (*note Completion::.). An empty argument to `C-x b' specifies the most recently selected buffer that is not displayed in any window. Most buffers are created when you visit files, or use Emacs commands that display text. You can also create a buffer explicitly by typing `C-x b BUFNAME ', which creates a new, empty buffer that is not visiting any file, and selects it for editing. The new buffer's major mode is determined by the value of `default-major-mode' (*note Major Modes::.). Buffers not visiting files are usually used for making notes to yourself. If you try to save one, you are asked for the file name to use. The function `switch-to-buffer-other-frame' is similar to `switch-to-buffer' except that it creates a new frame in which to display the selected buffer. Use `M-x switch-to-other-buffer' to visit the previous buffer. If you supply a positive integer N, the Nth most recent buffer is displayed. If you supply an argument of 0, the current buffer is moved to the bottom of the buffer stack. Note that you can also use `C-x C-f' and any other command for visiting a file to switch buffers. *Note Visiting::.  File: xemacs.info, Node: List Buffers, Next: Misc Buffer, Prev: Select Buffer, Up: Buffers Listing Existing Buffers ======================== `C-x C-b' List the existing buffers (`list-buffers'). To print a list of all existing buffers, type `C-x C-b'. Each line in the list shows one buffer's name, major mode, and visited file. A `*' at the beginning of a line indicates the buffer has been "modified". If several buffers are modified, it may be time to save some with `C-x s' (*note Saving::.). A `%' indicates a read-only buffer. A `.' marks the selected buffer. Here is an example of a buffer list: MR Buffer Size Mode File -- ------ ---- ---- ---- .* emacs.tex 383402 Texinfo /u2/emacs/man/emacs.tex *Help* 1287 Fundamental files.el 23076 Emacs-Lisp /u2/emacs/lisp/files.el % RMAIL 64042 RMAIL /u/rms/RMAIL *% man 747 Dired /u2/emacs/man/ net.emacs 343885 Fundamental /u/rms/net.emacs fileio.c 27691 C /u2/emacs/src/fileio.c NEWS 67340 Text /u2/emacs/etc/NEWS *scratch* 0 Lisp Interaction Note that the buffer `*Help*' was made by a help request; it is not visiting any file. The buffer `man' was made by Dired on the directory `/u2/emacs/man/'. As you move the mouse over the `*Buffer List*' buffer, the lines are highlighted. This visual cue indicates that clicking the right mouse button (`button3') will pop up a menu of commands on the buffer represented by this line. This menu duplicates most of those commands which are bound to keys in the `*Buffer List*' buffer.  File: xemacs.info, Node: Misc Buffer, Next: Kill Buffer, Prev: List Buffers, Up: Buffers Miscellaneous Buffer Operations =============================== `C-x C-q' Toggle read-only status of buffer (`toggle-read-only'). `M-x rename-buffer' Change the name of the current buffer. `M-x view-buffer' Scroll through a buffer. A buffer can be "read-only", which means that commands to change its text are not allowed. Normally, read-only buffers are created by subsystems such as Dired and Rmail that have special commands to operate on the text. Emacs also creates a read-only buffer if you visit a file that is protected. To make changes in a read-only buffer, use the command `C-x C-q' (`toggle-read-only'). It makes a read-only buffer writable, and makes a writable buffer read-only. This works by setting the variable `buffer-read-only', which has a local value in each buffer and makes a buffer read-only if its value is non-`nil'. `M-x rename-buffer' changes the name of the current buffer, prompting for the new name in the minibuffer. There is no default. If you specify a name that is used by a different buffer, an error is signalled and renaming is not done. `M-x view-buffer' is similar to `M-x view-file' (*note Misc File Ops::.), but it examines an already existing Emacs buffer. View mode provides convenient commands for scrolling through the buffer but not for changing it. When you exit View mode, the resulting value of point remains in effect. To copy text from one buffer to another, use the commands `M-x append-to-buffer' and `M-x insert-buffer'. *Note Accumulating Text::.  File: xemacs.info, Node: Kill Buffer, Next: Several Buffers, Prev: Misc Buffer, Up: Buffers Killing Buffers =============== After using Emacs for a while, you may accumulate a large number of buffers and may want to eliminate the ones you no longer need. There are several commands for doing this. `C-x k' Kill a buffer, specified by name (`kill-buffer'). `M-x kill-some-buffers' Offer to kill each buffer, one by one. `C-x k' (`kill-buffer') kills one buffer, whose name you specify in the minibuffer. If you type just in the minibuffer, the default, killing the current buffer, is used. If the current buffer is killed, the buffer that has been selected recently but does not appear in any window now is selected. If the buffer being killed contains unsaved changes, you are asked to confirm with `yes' before the buffer is killed. The command `M-x kill-some-buffers' asks about each buffer, one by one. An answer of `y' means to kill the buffer. Killing the current buffer or a buffer containing unsaved changes selects a new buffer or asks for confirmation just like `kill-buffer'.  File: xemacs.info, Node: Several Buffers, Prev: Kill Buffer, Up: Buffers Operating on Several Buffers ============================ The "buffer-menu" facility is like a "Dired for buffers"; it allows you to request operations on various Emacs buffers by editing a buffer containing a list of them. You can save buffers, kill them (here called "deleting" them, for consistency with Dired), or display them. `M-x buffer-menu' Begin editing a buffer listing all Emacs buffers. The command `buffer-menu' writes a list of all Emacs buffers into the buffer `*Buffer List*', and selects that buffer in Buffer Menu mode. The buffer is read-only. You can only change it using the special commands described in this section. Most of the commands are graphic characters. You can use Emacs cursor motion commands in the `*Buffer List*' buffer. If the cursor is on a line describing a buffer, the following special commands apply to that buffer: `d' Request to delete (kill) the buffer, then move down. A `D' before the buffer name on a line indicates a deletion request. Requested deletions actually take place when you use the `x' command. `k' Synonym for `d'. `C-d' Like `d' but move up afterwards instead of down. `s' Request to save the buffer. An `S' befor the buffer name on a line indicates the request. Requested saves actually take place when you use the `x' command. You can request both saving and deletion for the same buffer. `~' Mark buffer "unmodified". The command `~' does this immediately when typed. `x' Perform previously requested deletions and saves. `u' Remove any request made for the current line, and move down. `' Move to previous line and remove any request made for that line. All commands that add or remove flags to request later operations also move down a line. They accept a numeric argument as a repeat count, unless otherwise specified. There are also special commands to use the buffer list to select another buffer, and to specify one or more other buffers for display in additional windows. `1' Select the buffer in a full-frame window. This command takes effect immediately. `2' Immediately set up two windows, with this buffer in one and the buffer selected before `*Buffer List*' in the other. `f' Immediately select the buffer in place of the `*Buffer List*' buffer. `o' Immediately select the buffer in another window as if by `C-x 4 b', leaving `*Buffer List*' visible. `q' Immediately select this buffer, and display any buffers previously flagged with the `m' command in other windows. If there are no buffers flagged with `m', this command is equivalent to `1'. `m' Flag this buffer to be displayed in another window if the `q' command is used. The request shows as a `>' at the beginning of the line. The same buffer may not have both a delete request and a display request. Going back between a `buffer-menu' buffer and other Emacs buffers is easy. You can, for example, switch from the `*Buffer List*' buffer to another Emacs buffer, and edit there. You can then reselect the `buffer-menu' buffer and perform operations already requested, or you can kill that buffer or pay no further attention to it. All that `buffer-menu' does directly is create and select a suitable buffer, and turn on Buffer Menu mode. All the other capabilities of the buffer menu are implemented by special commands provided in Buffer Menu mode. The only difference between `buffer-menu' and `list-buffers' is that `buffer-menu' selects the `*Buffer List*' buffer and `list-buffers' does not. If you run `list-buffers' (that is, type `C-x C-b') and select the buffer list manually, you can use all the commands described here.  File: xemacs.info, Node: Windows, Next: Mule, Prev: Buffers, Up: Top Multiple Windows **************** Emacs can split the frame into two or many windows, which can display parts of different buffers or different parts of one buffer. If you are running XEmacs under X, that means you can have the X window that contains the Emacs frame have multiple subwindows. * Menu: * Basic Window:: Introduction to Emacs windows. * Split Window:: New windows are made by splitting existing windows. * Other Window:: Moving to another window or doing something to it. * Pop Up Window:: Finding a file or buffer in another window. * Change Window:: Deleting windows and changing their sizes.  File: xemacs.info, Node: Basic Window, Next: Split Window, Prev: Windows, Up: Windows Concepts of Emacs Windows ========================= When Emacs displays multiple windows, each window has one Emacs buffer designated for display. The same buffer may appear in more than one window; if it does, any changes in its text are displayed in all the windows that display it. Windows showing the same buffer can show different parts of it, because each window has its own value of point. At any time, one window is the "selected window"; the buffer displayed by that window is the current buffer. The cursor shows the location of point in that window. Each other window has a location of point as well, but since the terminal has only one cursor, it cannot show the location of point in the other windows. Commands to move point affect the value of point for the selected Emacs window only. They do not change the value of point in any other Emacs window, including those showing the same buffer. The same is true for commands such as `C-x b' to change the selected buffer in the selected window; they do not affect other windows at all. However, there are other commands such as `C-x 4 b' that select a different window and switch buffers in it. Also, all commands that display information in a window, including (for example) `C-h f' (`describe-function') and `C-x C-b' (`list-buffers'), work by switching buffers in a non-selected window without affecting the selected window. Each window has its own mode line, which displays the buffer name, modification status, and major and minor modes of the buffer that is displayed in the window. *Note Mode Line::, for details on the mode line.  File: xemacs.info, Node: Split Window, Next: Other Window, Prev: Basic Window, Up: Windows Splitting Windows ================= `C-x 2' Split the selected window into two windows, one above the other (`split-window-vertically'). `C-x 3' Split the selected window into two windows positioned side by side (`split-window-horizontally'). `C-x 6' Save the current window configuration in register REG (a letter). `C-x 7' Restore (make current) the window configuration in register REG (a letter). Use with a register previously set with `C-x 6'. The command `C-x 2' (`split-window-vertically') breaks the selected window into two windows, one above the other. Both windows start out displaying the same buffer, with the same value of point. By default each of the two windows gets half the height of the window that was split. A numeric argument specifies how many lines to give to the top window. `C-x 3' (`split-window-horizontally') breaks the selected window into two side-by-side windows. A numeric argument specifies how many columns to give the one on the left. A line of vertical bars separates the two windows. Windows that are not the full width of the frame have truncated mode lines which do not always appear in inverse video, because Emacs display routines cannot display a region of inverse video that is only part of a line on the screen. When a window is less than the full width, many text lines are too long to fit. Continuing all those lines might be confusing. Set the variable `truncate-partial-width-windows' to non-`nil' to force truncation in all windows less than the full width of the frame, independent of the buffer and its value for `truncate-lines'. *Note Continuation Lines::. Horizontal scrolling is often used in side-by-side windows. *Note Display::. You can resize a window and store that configuration in a register by supplying a REGISTER argument to `window-configuration-to-register' (`C-x 6'). To return to the window configuration established with `window-configuration-to-register', use `jump-to-register' (`C-x j').  File: xemacs.info, Node: Other Window, Next: Pop Up Window, Prev: Split Window, Up: Windows Using Other Windows =================== `C-x o' Select another window (`other-window'). That is the letter `o', not zero. `M-C-v' Scroll the next window (`scroll-other-window'). `M-x compare-windows' Find the next place where the text in the selected window does not match the text in the next window. `M-x other-window-any-frame N' Select the Nth different window on any frame. To select a different window, use `C-x o' (`other-window'). That is an `o', for `other', not a zero. When there are more than two windows, the command moves through all the windows in a cyclic order, generally top to bottom and left to right. From the rightmost and bottommost window, it goes back to the one at the upper left corner. A numeric argument, N, moves several steps in the cyclic order of windows. A negative numeric argument moves around the cycle in the opposite order. If the optional second argument ALL-FRAMES is non-`nil', the function cycles through all frames. When the minibuffer is active, the minibuffer is the last window in the cycle; you can switch from the minibuffer window to one of the other windows, and later switch back and finish supplying the minibuffer argument that is requested. *Note Minibuffer Edit::. The command `M-x other-window-any-frame' also selects the window N steps away in the cyclic order. However, unlike `other-window', this command selects a window on the next or previous frame instead of wrapping around to the top or bottom of the current frame, when there are no more windows. The usual scrolling commands (*note Display::.) apply to the selected window only. `M-C-v' (`scroll-other-window') scrolls the window that `C-x o' would select. Like `C-v', it takes positive and negative arguments. The command `M-x compare-windows' compares the text in the current window with the text in the next window. Comparison starts at point in each window. Point moves forward in each window, a character at a time, until the next set of characters in the two windows are different. Then the command is finished. A prefix argument IGNORE-WHITESPACE means ignore changes in whitespace. The variable `compare-windows-whitespace' controls how whitespace is skipped. If `compare-ignore-case' is non-`nil', changes in case are also ignored.  File: xemacs.info, Node: Pop Up Window, Next: Change Window, Prev: Other Window, Up: Windows Displaying in Another Window ============================ `C-x 4' is a prefix key for commands that select another window (splitting the window if there is only one) and select a buffer in that window. Different `C-x 4' commands have different ways of finding the buffer to select. `C-x 4 b BUFNAME ' Select buffer BUFNAME in another window. This runs `switch-to-buffer-other-window'. `C-x 4 f FILENAME ' Visit file FILENAME and select its buffer in another window. This runs `find-file-other-window'. *Note Visiting::. `C-x 4 d DIRECTORY ' Select a Dired buffer for directory DIRECTORY in another window. This runs `dired-other-window'. *Note Dired::. `C-x 4 m' Start composing a mail message in another window. This runs `mail-other-window', and its same-window version is `C-x m' (*note Sending Mail::.). `C-x 4 .' Find a tag in the current tag table in another window. This runs `find-tag-other-window', the multiple-window variant of `M-.' (*note Tags::.). If the variable `display-buffer-function' is non-`nil', its value is the function to call to handle `display-buffer'. It receives two arguments, the buffer and a flag that if non-`nil' means that the currently selected window is not acceptable. Commands such as `switch-to-buffer-other-window' and `find-file-other-window' work using this function.  File: xemacs.info, Node: Change Window, Prev: Pop Up Window, Up: Windows Deleting and Rearranging Windows ================================ `C-x 0' Get rid of the selected window (`delete-window'). That is a zero. If there is more than one Emacs frame, deleting the sole remaining window on that frame deletes the frame as well. If the current frame is the only frame, it is not deleted. `C-x 1' Get rid of all windows except the selected one (`delete-other-windows'). `C-x ^' Make the selected window taller, at the expense of the other(s) (`enlarge-window'). `C-x }' Make the selected window wider (`enlarge-window-horizontally'). To delete a window, type `C-x 0' (`delete-window'). (That is a zero.) The space occupied by the deleted window is distributed among the other active windows (but not the minibuffer window, even if that is active at the time). Once a window is deleted, its attributes are forgotten; there is no automatic way to make another window of the same shape or showing the same buffer. The buffer continues to exist, and you can select it in any window with `C-x b'. `C-x 1' (`delete-other-windows') is more powerful than `C-x 0'; it deletes all the windows except the selected one (and the minibuffer). The selected window expands to use the whole frame except for the echo area. To readjust the division of space among existing windows, use `C-x ^' (`enlarge-window'). It makes the currently selected window longer by one line or as many lines as a numeric argument specifies. With a negative argument, it makes the selected window smaller. `C-x }' (`enlarge-window-horizontally') makes the selected window wider by the specified number of columns. The extra screen space given to a window comes from one of its neighbors, if that is possible; otherwise, all the competing windows are shrunk in the same proportion. If this makes some windows too small, those windows are deleted and their space is divided up. Minimum window size is specified by the variables `window-min-height' and `window-min-width'. You can also resize windows within a frame by clicking the left mouse button on a modeline, and dragging. Clicking the right button on a mode line pops up a menu of common window manager operations. This menu contains the following options: Delete Window Remove the window above this modeline from the frame. Delete Other Windows Delete all windows on the frame except for the one above this modeline. Split Window Split the window above the mode line in half, creating another window. Split Window Horizontally Split the window above the mode line in half horizontally, so that there will be two windows side-by-side. Balance Windows Readjust the sizes of all windows on the frame until all windows have roughly the same number of lines.  File: xemacs.info, Node: Mule, Next: Major Modes, Prev: Windows, Up: Top World Scripts Support ********************* If you compile XEmacs with mule option, it supports a wide variety of world scripts, including Latin script, as well as Arabic script, Simplified Chinese script (for mainland of China), Traditional Chinese script (for Taiwan and Hong-Kong), Greek script, Hebrew script, IPA symbols, Japanese scripts (Hiragana, Katakana and Kanji), Korean scripts (Hangul and Hanja) and Cyrillic script (for Beylorussian, Bulgarian, Russian, Serbian and Ukrainian). These features have been merged from the modified version of Emacs known as MULE (for "MULti-lingual Enhancement to GNU Emacs"). * Menu: * Mule Intro:: Basic concepts of Mule. * Language Environments:: Setting things up for the language you use. * Input Methods:: Entering text characters not on your keyboard. * Select Input Method:: Specifying your choice of input methods. * Coding Systems:: Character set conversion when you read and write files, and so on. * Recognize Coding:: How XEmacs figures out which conversion to use. * Specify Coding:: Various ways to choose which conversion to use.  File: xemacs.info, Node: Mule Intro, Next: Language Environments, Prev: Mule, Up: Mule Introduction to world scripts ============================= The users of these scripts have established many more-or-less standard coding systems for storing files. XEmacs translates between the internal character encoding and various other coding systems when reading and writing files, when exchanging data with subprocesses, and (in some cases) in the `C-q' command (see below). The command `C-h h' (`view-hello-file') displays the file `etc/HELLO', which shows how to say "hello" in many languages. This illustrates various scripts. Keyboards, even in the countries where these character sets are used, generally don't have keys for all the characters in them. So XEmacs supports various "input methods", typically one for each script or language, to make it convenient to type them. The prefix key `C-x ' is used for commands that pertain to world scripts, coding systems, and input methods.  File: xemacs.info, Node: Language Environments, Next: Input Methods, Prev: Mule Intro, Up: Mule Language Environments ===================== All supported character sets are supported in XEmacs buffers if it is compile with mule; there is no need to select a particular language in order to display its characters in an XEmacs buffer. However, it is important to select a "language environment" in order to set various defaults. The language environment really represents a choice of preferred script (more or less) rather that a choice of language. The language environment controls which coding systems to recognize when reading text (*note Recognize Coding::.). This applies to files, incoming mail, netnews, and any other text you read into XEmacs. It may also specify the default coding system to use when you create a file. Each language environment also specifies a default input method. The command to select a language environment is `M-x set-language-environment'. It makes no difference which buffer is current when you use this command, because the effects apply globally to the XEmacs session. The supported language environments include: Chinese-BIG5, Chinese-CNS, Chinese-GB, Cyrillic-ISO, English, Ethiopic, Greek, Japanese, Korean, Latin-1, Latin-2, Latin-3, Latin-4, Latin-5. Some operating systems let you specify the language you are using by setting locale environment variables. XEmacs handles one common special case of this: if your locale name for character types contains the string `8859-N', XEmacs automatically selects the corresponding language environment. To display information about the effects of a certain language environment LANG-ENV, use the command `C-h L LANG-ENV ' (`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. By default, this command describes the chosen language environment.  File: xemacs.info, Node: Input Methods, Next: Select Input Method, Prev: Language Environments, Up: Mule Input Methods ============= An "input method" is a kind of character conversion designed specifically for interactive input. In XEmacs, typically each language has its own input method; sometimes several languages which 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 ASCII letters into another alphabet. This is how the Greek and Russian input methods work. A more powerful technique is composition: converting sequences of characters into one letter. Many European input methods use composition to produce a single non-ASCII letter from a sequence that consists of a letter followed by accent characters. For example, some methods convert the sequence `'a' into a single accented letter. 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 which make up a whole syllable are mapped into one syllable sign. Chinese and Japanese require more complex methods. In Chinese input methods, first you enter the phonetic spelling of a Chinese word (in input method `chinese-py', among others), or a sequence of portions of the character (input methods `chinese-4corner' and `chinese-sw', and others). Since one phonetic spelling typically corresponds to many different Chinese characters, you must select one of the alternatives using special XEmacs commands. Keys such as `C-f', `C-b', `C-n', `C-p', and digits have special definitions in this situation, used for selecting among the alternatives. displays a buffer showing all the possibilities. In Japanese input methods, first you input a whole word using phonetic spelling; then, after the word is in the buffer, XEmacs converts it into one or more characters using a large dictionary. One phonetic spelling corresponds to many differently written Japanese words, so you must select one of them; use `C-n' and `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 `latin-1-postfix', the sequence `e '' combines to form an `e' with an accent. What if you want to enter them as separate characters? One way is to type the accent twice; that is a special feature for entering the separate letter and accent. For example, `e ' '' gives you the two characters `e''. Another way is to type another letter after the `e'--something that won't combine with that--and immediately delete it. For example, you could type `e e '' to get separate `e' and `''. Another method, more general but not quite as easy to type, is to use `C-\ C-\' between two characters to stop them from combining. This is the command `C-\' (`toggle-input-method') used twice. *Note Select Input Method::. `C-\ C-\' is especially useful inside an incremental search, because stops waiting for more characters to combine, and starts searching for what you have already entered. The variables `input-method-highlight-flag' and `input-method-verbose-flag' control how input methods explain what is happening. If `input-method-highlight-flag' is non-`nil', the partial sequence is highlighted in the buffer. If `input-method-verbose-flag' is non-`nil', the list of possible characters to type next is displayed in the echo area (but not when you are in the minibuffer).  File: xemacs.info, Node: Select Input Method, Next: Coding Systems, Prev: Input Methods, Up: Mule Selecting an Input Method ========================= `C-\' Enable or disable use of the selected input method. `C-x C-\ METHOD ' Select a new input method for the current buffer. `C-h I METHOD ' `C-h C-\ METHOD ' Describe the input method METHOD (`describe-input-method'). By default, it describes the current input method (if any). `M-x list-input-methods' Display a list of all the supported input methods. To choose an input method for the current buffer, use `C-x C-\' (`select-input-method'). This command reads the input method name with the minibuffer; the name normally starts with the language environment that it is meant to be used with. The variable `current-input-method' records which input method is selected. Input methods use various sequences of ASCII characters to stand for non-ASCII characters. Sometimes it is useful to turn off the input method temporarily. To do this, type `C-\' (`toggle-input-method'). To reenable the input method, type `C-\' again. If you type `C-\' and you have not yet selected an input method, it prompts for you to specify one. This has the same effect as using `C-x C-\' to specify an 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 `C-\'. The variable `default-input-method' specifies the default input method (`nil' means there is none). 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 `M-x quail-set-keyboard-layout'. To display a list of all the supported input methods, type `M-x list-input-methods'. The list gives information about each input method, including the string that stands for it in the mode line.  File: xemacs.info, Node: Coding Systems, Next: Recognize Coding, Prev: Select Input Method, Up: Mule Coding Systems ============== Users of various languages have established many more-or-less standard coding systems for representing them. XEmacs 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. XEmacs 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 `iso'. There are also special coding systems `binary' and `no-conversion' which do not convert printing characters at all. In addition to converting various representations of non-ASCII characters, a coding system can perform end-of-line conversion. XEmacs handles three different conventions for how to separate lines in a file: newline, carriage-return linefeed, and just carriage-return. `C-h C CODING ' Describe coding system CODING. `C-h C ' Describe the coding systems currently in use. `M-x list-coding-systems' Display a list of all the supported coding systems. The command `C-h C' (`describe-coding-system') displays information about particular coding systems. You can specify a coding system name as 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 (*note Recognize Coding::.). To display a list of all the supported coding systems, type `M-x list-coding-systems'. The list gives information about each coding system, including the letter that stands for it in the mode line (*note Mode Line::.). Each of the coding systems that appear in this list--except for `binary', 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 carriage-return linefeed between lines, that 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: `...-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.) `...-dos' Assume the file uses carriage-return linefeed to separate lines, and do the appropriate conversion. (This is the convention normally used on Microsoft systems.) `...-mac' Assume the file uses carriage-return to separate lines, and do the appropriate conversion. (This is the convention normally used on the Macintosh system.) These variant coding systems are omitted from the `list-coding-systems' display for brevity, since they are entirely predictable. For example, the coding system `iso-8859-1' has variants `iso-8859-1-unix', `iso-8859-1-dos' and `iso-8859-1-mac'. In contrast, the coding system `binary' specifies no character code conversion at all--none for non-Latin-1 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. The easiest way to edit a file with no conversion of any kind is with the `M-x find-file-literally' command. This uses `binary', and also suppresses other XEmacs features that might convert the file contents before you see them. *Note Visiting::. The coding system `no-conversion' means that the file contains non-Latin-1 characters stored with the internal XEmacs encoding. It 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.  File: xemacs.info, Node: Recognize Coding, Next: Specify Coding, Prev: Coding Systems, Up: Mule Recognizing Coding Systems ========================== Most of the time, XEmacs can recognize which coding system to use for any given file-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. XEmacs handles this situation by means of a priority list of coding systems. Whenever XEmacs reads a file, if you do not specify the coding system to use, XEmacs 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 (*note Language Environments::.). For example, if you use French, you probably want XEmacs 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. However, you can alter the priority list in detail with the command `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. Sometimes a file name indicates which coding system to use for the file. The variable `file-coding-system-alist' specifies this correspondence. There is a special function `modify-coding-system-alist' for adding elements to this list. For example, to read and write all `.txt' using the coding system `china-iso-8bit', you can execute this Lisp expression: (modify-coding-system-alist 'file "\\.txt\\'" 'china-iso-8bit) The first argument should be `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. You can specify the coding system for a particular file using the `-*-...-*-' construct at the beginning of a file, or a local variables list at the end (*note File Variables::.). You do this by defining a value for the "variable" named `coding'. XEmacs does not really have a variable `coding'; instead of setting a variable, it uses the specified coding system for the file. For example, `-*-mode: C; coding: iso-8859-1;-*-' specifies use of the iso-8859-1 coding system, as well as C mode. Once XEmacs has chosen a coding system for a buffer, it stores that coding system in `buffer-file-coding-system' and uses that coding system, by default, for operations that write from this buffer into a file. This includes the commands `save-buffer' and `write-region'. If you want to write files from this buffer using a different coding system, you can specify a different coding system for the buffer using `set-buffer-file-coding-system' (*note Specify Coding::.).