SGI Freeware 1999 August

home *** CD-ROM | disk | FTP | other *** search

/ SGI Freeware 1999 August / SGI Freeware 1999 August.iso / dist / fw_xemacs.idb / usr / freeware / lib / xemacs-20.4 / info / xemacs.info-8.z / xemacs.info-8

Wrap

GNU Info File | 1998-05-21 | 49.3 KB | 1,151 lines

This is Info file ../../info/xemacs.info, produced by Makeinfo version 1.68 from the input file xemacs.texi. 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: 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. `<DEL>' 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 <RET>' Select buffer BUFNAME in another window. This runs `switch-to-buffer-other-window'. `C-x 4 f FILENAME <RET>' Visit file FILENAME and select its buffer in another window. This runs `find-file-other-window'. *Note Visiting::. `C-x 4 d DIRECTORY <RET>' 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 <RET>' 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 <RET>' (`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. <TAB> 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 <DEL> '' 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 <RET> C-\ METHOD <RET>' Select a new input method for the current buffer. `C-h I METHOD <RET>' `C-h C-\ METHOD <RET>' 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 <RET> 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 <RET> 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 <RET>' Describe coding system CODING. `C-h C <RET>' 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::.). File: xemacs.info, Node: Specify Coding, Prev: Recognize Coding, Up: Mule Specifying a Coding System ========================== In cases where XEmacs does not automatically choose the right coding system, you can use these commands to specify one: `C-x <RET> f CODING <RET>' Use coding system CODING for the visited file in the current buffer. `C-x <RET> c CODING <RET>' Specify coding system CODING for the immediately following command. `C-x <RET> k CODING <RET>' Use coding system CODING for keyboard input. `C-x <RET> t CODING <RET>' Use coding system CODING for terminal output. `C-x <RET> p CODING <RET>' Use coding system CODING for subprocess input and output in the current buffer. The command `C-x RET f' (`set-buffer-file-coding-system') specifies the file coding system for the current buffer--in other words, which coding system to use when saving or rereading the visited file. You specify which coding system using the minibuffer. Since this command applies to a file you have already visited, it affects only the way the file is saved. Another way to specify the coding system for a file is when you visit the file. First use the command `C-x <RET> c' (`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 *the immediately following command*. So if the immediately following command is `C-x C-f', for example, it reads the file using that coding system (and records the coding system for when the file is saved). Or if the immediately following command is `C-x C-w', it writes the file using that coding system. Other file commands affected by a specified coding system include `C-x C-i' and `C-x C-v', as well as the other-window variants of `C-x C-f'. In addition, if you run some file input commands with the precedent `C-u', you can specify coding system to read from minibuffer. So if the immediately following command is `C-x C-f', for example, it reads the file using that coding system (and records the coding system for when the file is saved). Other file commands affected by a specified coding system include `C-x C-i' and `C-x C-v', as well as the other-window variants of `C-x C-f'. The variable `default-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. The command `C-x <RET> t' (`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. By default, output to the terminal is not translated at all. The command `C-x <RET> k' (`set-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-ASCII graphic characters--for example, some terminals designed for ISO Latin-1 or subsets of it. By default, keyboard input is not translated at all. 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 ASCII printing characters. Coding systems typically translate sequences of non-graphic characters. The command `C-x <RET> p' (`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. By default, process input and output are not translated at all. The variable `file-name-coding-system' specifies a coding system to use for encoding file names. If you set the variable to a coding system name (as a Lisp symbol or a string), XEmacs encodes file names using that coding system for all file operations. This makes it possible to use non-Latin-1 characters in file names--or, at least, those non-Latin-1 characters which the specified coding system can encode. By default, this variable is `nil', which implies that you cannot use non-Latin-1 characters in file names. File: xemacs.info, Node: Major Modes, Next: Indentation, Prev: Mule, Up: Top Major Modes *********** Emacs has many different "major modes", each of which customizes Emacs for editing text of a particular sort. The major modes are mutually exclusive; at any time, each buffer has one major mode. The mode line normally contains the name of the current major mode in parentheses. *Note Mode Line::. The least specialized major mode is called "Fundamental mode". This mode has no mode-specific redefinitions or variable settings. Each Emacs command behaves in its most general manner, and each option is in its default state. For editing any specific type of text, such as Lisp code or English text, you should switch to the appropriate major mode, such as Lisp mode or Text mode. Selecting a major mode changes the meanings of a few keys to become more specifically adapted to the language being edited. <TAB>, <DEL>, and <LFD> are changed frequently. In addition, commands which handle comments use the mode to determine how to delimit comments. Many major modes redefine the syntactical properties of characters appearing in the buffer. *Note Syntax::. The major modes fall into three major groups. Lisp mode (which has several variants), C mode, and Muddle mode are for specific programming languages. Text mode, Nroff mode, TeX mode, and Outline mode are for editing English text. The remaining major modes are not intended for use on users' files; they are used in buffers created by Emacs for specific purposes and include Dired mode for buffers made by Dired (*note Dired::.), Mail mode for buffers made by `C-x m' (*note Sending Mail::.), and Shell mode for buffers used for communicating with an inferior shell process (*note Interactive Shell::.). Most programming language major modes specify that only blank lines separate paragraphs. This is so that the paragraph commands remain useful. *Note Paragraphs::. They also cause Auto Fill mode to use the definition of <TAB> to indent the new lines it creates. This is because most lines in a program are usually indented. *Note Indentation::. * Menu: * Choosing Modes:: How major modes are specified or chosen. File: xemacs.info, Node: Choosing Modes, Prev: Major Modes, Up: Major Modes Choosing Major Modes ==================== You can select a major mode explicitly for the current buffer, but most of the time Emacs determines which mode to use based on the file name or some text in the file. Use a `M-x' command to explicitly select a new major mode. Add `-mode' to the name of a major mode to get the name of a command to select that mode. For example, to enter Lisp mode, execute `M-x lisp-mode'. When you visit a file, Emacs usually chooses the right major mode based on the file's name. For example, files whose names end in `.c' are edited in C mode. The variable `auto-mode-alist' controls the correspondence between file names and major mode. Its value is a list in which each element has the form: (REGEXP . MODE-FUNCTION) For example, one element normally found in the list has the form `("\\.c$" . c-mode)'. It is responsible for selecting C mode for files whose names end in `.c'. (Note that `\\' is needed in Lisp syntax to include a `\' in the string, which is needed to suppress the special meaning of `.' in regexps.) The only practical way to change this variable is with Lisp code. You can specify which major mode should be used for editing a certain file by a special sort of text in the first non-blank line of the file. The mode name should appear in this line both preceded and followed by `-*-'. Other text may appear on the line as well. For example, ;-*-Lisp-*- tells Emacs to use Lisp mode. Note how the semicolon is used to make Lisp treat this line as a comment. Such an explicit specification overrides any default mode based on the file name. Another format of mode specification is: -*-Mode: MODENAME;-*- which allows other things besides the major mode name to be specified. However, Emacs does not look for anything except the mode name. The major mode can also be specified in a local variables list. *Note File Variables::. When you visit a file that does not specify a major mode to use, or when you create a new buffer with `C-x b', Emacs uses the major mode specified by the variable `default-major-mode'. Normally this value is the symbol `fundamental-mode', which specifies Fundamental mode. If `default-major-mode' is `nil', the major mode is taken from the previously selected buffer. File: xemacs.info, Node: Indentation, Next: Text, Prev: Major Modes, Up: Top Indentation *********** `<TAB>' Indent current line "appropriately" in a mode-dependent fashion. `<LFD>' Perform <RET> followed by <TAB> (`newline-and-indent'). `M-^' Merge two lines (`delete-indentation'). This would cancel out the effect of <LFD>. `C-M-o' Split line at point; text on the line after point becomes a new line indented to the same column that it now starts in (`split-line'). `M-m' Move (forward or back) to the first non-blank character on the current line (`back-to-indentation'). `C-M-\' Indent several lines to same column (`indent-region'). `C-x <TAB>' Shift block of lines rigidly right or left (`indent-rigidly'). `M-i' Indent from point to the next prespecified tab stop column (`tab-to-tab-stop'). `M-x indent-relative' Indent from point to under an indentation point in the previous line. Most programming languages have some indentation convention. For Lisp code, lines are indented according to their nesting in parentheses. The same general idea is used for C code, though details differ. Use the <TAB> command to indent a line whatever the language. Each major mode defines this command to perform indentation appropriate for the particular language. In Lisp mode, <TAB> aligns a line according to its depth in parentheses. No matter where in the line you are when you type <TAB>, it aligns the line as a whole. In C mode, <TAB> implements a subtle and sophisticated indentation style that knows about many aspects of C syntax. In Text mode, <TAB> runs the command `tab-to-tab-stop', which indents to the next tab stop column. You can set the tab stops with `M-x edit-tab-stops'. * Menu: * Indentation Commands:: Various commands and techniques for indentation. * Tab Stops:: You can set arbitrary "tab stops" and then indent to the next tab stop when you want to. * Just Spaces:: You can request indentation using just spaces. File: xemacs.info, Node: Indentation Commands, Next: Tab Stops, Prev: Indentation, Up: Indentation Indentation Commands and Techniques =================================== If you just want to insert a tab character in the buffer, you can type `C-q <TAB>'. To move over the indentation on a line, type `Meta-m' (`back-to-indentation'). This command, given anywhere on a line, positions point at the first non-blank character on the line. To insert an indented line before the current line, type `C-a C-o <TAB>'. To make an indented line after the current line, use `C-e <LFD>'. `C-M-o' (`split-line') moves the text from point to the end of the line vertically down, so that the current line becomes two lines. `C-M-o' first moves point forward over any spaces and tabs. Then it inserts after point a newline and enough indentation to reach the same column point is on. Point remains before the inserted newline; in this regard, `C-M-o' resembles `C-o'. To join two lines cleanly, use the `Meta-^' (`delete-indentation') command to delete the indentation at the front of the current line, and the line boundary as well. Empty spaces are replaced by a single space, or by no space if at the beginning of a line, before a close parenthesis, or after an open parenthesis. To delete just the indentation of a line, go to the beginning of the line and use `Meta-\' (`delete-horizontal-space'), which deletes all spaces and tabs around the cursor. There are also commands for changing the indentation of several lines at once. `Control-Meta-\' (`indent-region') gives each line which begins in the region the "usual" indentation by invoking <TAB> at the beginning of the line. A numeric argument specifies the column to indent to. Each line is shifted left or right so that its first non-blank character appears in that column. `C-x <TAB>' (`indent-rigidly') moves all the lines in the region right by its argument (left, for negative arguments). The whole group of lines moves rigidly sideways, which is how the command gets its name. `M-x indent-relative' indents at point based on the previous line (actually, the last non-empty line.) It inserts whitespace at point, moving point, until it is underneath an indentation point in the previous line. An indentation point is the end of a sequence of whitespace or the end of the line. If point is farther right than any indentation point in the previous line, the whitespace before point is deleted and the first indentation point then applicable is used. If no indentation point is applicable even then, `tab-to-tab-stop' is run (see next section). `indent-relative' is the definition of <TAB> in Indented Text mode. *Note Text::. File: xemacs.info, Node: Tab Stops, Next: Just Spaces, Prev: Indentation Commands, Up: Indentation Tab Stops ========= For typing in tables, you can use Text mode's definition of <TAB>, `tab-to-tab-stop'. This command inserts indentation before point, enough to reach the next tab stop column. Even if you are not in Text mode, this function is associated with `M-i' anyway. You can arbitrarily set the tab stops used by `M-i'. They are stored as a list of column-numbers in increasing order in the variable `tab-stop-list'. The convenient way to set the tab stops is using `M-x edit-tab-stops', which creates and selects a buffer containing a description of the tab stop settings. You can edit this buffer to specify different tab stops, and then type `C-c C-c' to make those new tab stops take effect. In the tab stop buffer, `C-c C-c' runs the function `edit-tab-stops-note-changes' rather than the default `save-buffer'. `edit-tab-stops' records which buffer was current when you invoked it, and stores the tab stops in that buffer. Normally all buffers share the same tab stops and changing them in one buffer affects all. If you make `tab-stop-list' local in one buffer `edit-tab-stops' in that buffer edits only the local settings. Below is the text representing ordinary tab stops every eight columns: : : : : : : 0 1 2 3 4 0123456789012345678901234567890123456789012345678 To install changes, type C-c C-c The first line contains a colon at each tab stop. The remaining lines help you see where the colons are and tell you what to do. Note that the tab stops that control `tab-to-tab-stop' have nothing to do with displaying tab characters in the buffer. *Note Display Vars::, for more information on that.