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GNU Info File | 1995-09-11 | 39.6 KB | 939 lines

This is Info file ../info/emacs, produced by Makeinfo-1.55 from the input file emacs.texi. File: emacs, Node: Named ASCII Chars, Next: Mouse Buttons, Prev: Function Keys, Up: Key Bindings Named ASCII Control Characters ------------------------------ TAB, RET, BS, LFD, ESC and DEL started out as names for certain ASCII control characters, used so often that they have special keys of their own. Later, users found it convenient to distinguish in Emacs between these keys and the "same" control characters typed with the CTRL key. Emacs 19 distinguishes these two kinds of input, when used with the X Window System. It treats the "special" keys as function keys named `tab', `return', `backspace', `linefeed', `escape', and `delete'. These function keys translate automatically into the corresponding ASCII characters *if* they have no bindings of their own. As a result, neither users nor Lisp programs need to pay attention to the distinction unless they care to. If you do not want to distinguish between (for example) TAB and `C-i', make just one binding, for the ASCII character TAB (octal code 011). If you do want to distinguish, make one binding for this ASCII character, and another for the "function key" `tab'. With an ordinary ASCII terminal, there is no way to distinguish between TAB and `C-i' (and likewise for other such pairs), because the terminal sends the same character in both cases. File: emacs, Node: Mouse Buttons, Next: Disabling, Prev: Named ASCII Chars, Up: Key Bindings Rebinding Mouse Buttons ----------------------- Emacs uses Lisp symbols to designate mouse buttons, too. The ordinary mouse events in Emacs are "click" events; these happen when you press a button and release it without moving the mouse. You can also get "drag" events, when you move the mouse while holding the button down. Drag events happen when you finally let go of the button. The symbols for basic click events are `mouse-1' for the leftmost button, `mouse-2' for the next, and so on. Here is how you can redefine the second mouse button to split the current window: (global-set-key [mouse-2] 'split-window-vertically) The symbols for drag events are similar, but have the prefix `drag-' before the word `mouse'. For example, dragging the first button generates a `drag-mouse-1' event. You can also define bindings for events that occur when a mouse button is pressed down. These events start with `down-' instead of `drag-'. Such events are generated only if they have key bindings. When you get a button-down event, a corresponding click or drag event will always follow. If you wish, you can distinguish single, double, and triple clicks. A double click means clicking a mouse button twice in approximately the same place. The first click generates an ordinary click event. The second click, if it comes soon enough, generates a double-click event instead. The event type for a double click event starts with `double-': for example, `double-mouse-3'. This means that you can give a special meaning to the second click at the same place, but it must act on the assumption that the ordinary single click definition has run when the first click was received. This constrains what you can do with double clicks, but user interface designers say that this constraint ought to be followed in any case. A double click should do something similar to the single click, only "more so". The command for the double-click event should perform the extra work for the double click. If a double-click event has no binding, it changes to the corresponding single-click event. Thus, if you don't define a particular double click specially, it executes the single-click command twice. Emacs also supports triple-click events whose names start with `triple-'. Emacs does not distinguish quadruple clicks as event types; clicks beyond the third generate additional triple-click events. However, the full number of clicks is recorded in the event list, so you can distinguish if you really want to. We don't recommend distinct meanings for more than three clicks, but sometimes it is useful for subsequent clicks to cycle through the same set of three meanings, so that four clicks are equivalent to one click, five are equivalent to two, and six are equivalent to three. Emacs also records multiple presses in drag and button-down events. For example, when you press a button twice, then move the mouse while holding the button, Emacs gets a `double-drag-' event. And at the moment when you press it down for the second time, Emacs gets a `double-down-' event (which is ignored, like all button-down events, if it has no binding). The variable `double-click-time' specifies how long may elapse between clicks that are recognized as a pair. Its value is measured in milliseconds. If the value is `nil', double clicks are not detected at all. If the value is `t', then there is no time limit. The symbols for mouse events also indicate the status of the modifier keys, with the usual prefixes `C-', `M-', `H-', `s-', `A-' and `S-'. These always precede `double-' or `triple-', which always precede `drag-' or `down-'. A frame includes areas that don't show text from the buffer, such as the mode line and the scroll bar. You can tell whether a mouse button comes from a special area of the screen by means of dummy "prefix keys." For example, if you click the mouse in the mode line, you get the prefix key `mode-line' before the ordinary mouse-button symbol. Thus, here is how to define the command for clicking the first button in a mode line to run `scroll-up': (global-set-key [mode-line mouse-1] 'scroll-up) Here is the complete list of these dummy prefix keys and their meanings: `mode-line' The mouse was in the mode line of a window. `vertical-line' The mouse was in the vertical line separating side-by-side windows. (If you use scroll bars, they appear in place of these vertical lines.) `vertical-scroll-bar' The mouse was in a vertical scroll bar. (This is the only kind of scroll bar Emacs currently supports.) You can put more than one mouse button in a key sequence, but it isn't usual to do so. File: emacs, Node: Disabling, Prev: Mouse Buttons, Up: Key Bindings Disabling Commands ------------------ Disabling a command marks the command as requiring confirmation before it can be executed. The purpose of disabling a command is to prevent beginning users from executing it by accident and being confused. An attempt to invoke a disabled command interactively in Emacs displays a window containing the command's name, its documentation, and some instructions on what to do immediately; then Emacs asks for input saying whether to execute the command as requested, enable it and execute it, or cancel. If you decide to enable the command, you are asked whether to do this permanently or just for the current session. Enabling permanently works by automatically editing your `.emacs' file. The direct mechanism for disabling a command is to put a non-`nil' `disabled' property on the Lisp symbol for the command. Here is the Lisp program to do this: (put 'delete-region 'disabled t) If the value of the `disabled' property is a string, that string is included in the message printed when the command is used: (put 'delete-region 'disabled "It's better to use `kill-region' instead.\n") You can make a command disabled either by editing the `.emacs' file directly or with the command `M-x disable-command', which edits the `.emacs' file for you. Likewise, `M-x enable-command' edits `.emacs' to enable a command permanently. *Note Init File::. Whether a command is disabled is independent of what key is used to invoke it; disabling also applies if the command is invoked using `M-x'. Disabling a command has no effect on calling it as a function from Lisp programs. File: emacs, Node: Keyboard Translations, Next: Syntax, Prev: Key Bindings, Up: Customization Keyboard Translations ===================== Some keyboards do not make it convenient to send all the special characters that Emacs uses. The most common problem case is the DEL character. Some keyboards provide no convenient way to type this very important character--usually because they were designed to expect the character `C-h' to be used for deletion. On these keyboard, if you press the key normally used for deletion, Emacs handles the `C-h' as a prefix character and offers you a list of help options, which is not what you want. You can work around this problem within Emacs by setting up keyboard translations to turn `C-h' into DEL and DEL into `C-h', as follows: ;; Translate `C-h' to DEL. (keyboard-translate ?\C-h ?\C-?) ;; Translate DEL to `C-h'. (keyboard-translate ?\C-? ?\C-h) Keyboard translations are not the same as key bindings in keymaps (*note Keymaps::.). Emacs contains numerous keymaps that apply in different situations, but there is only one set of keyboard translations, and it applies to every character that Emacs reads from the terminal. Keyboard translations take place at the lowest level of input processing; the keys that are looked up in keymaps contain the characters that result from keyboard translation. Under X, the keyboard key named DELETE is a function key and is distinct from the ASCII character named DEL. *Note Named ASCII Chars::. Keyboard translations affect only ASCII character input, not function keys; thus, the above example used under X does not affect the DELETE key. However, the translation above isn't necessary under X, because Emacs can also distinguish between the BACKSPACE key and `C-h'; and it normally treats BACKSPACE as DEL. For full information about how to use keyboard translations, see *Note Translating Input: (elisp)Translating Input. File: emacs, Node: Syntax, Next: Init File, Prev: Keyboard Translations, Up: Customization The Syntax Table ================ All the Emacs commands which parse words or balance parentheses are controlled by the "syntax table". The syntax table says which characters are opening delimiters, which are parts of words, which are string quotes, and so on. Each major mode has its own syntax table (though sometimes related major modes use the same one) which it installs in each buffer that uses that major mode. The syntax table installed in the current buffer is the one that all commands use, so we call it "the" syntax table. A syntax table is a Lisp object, a vector of length 256 whose elements are numbers. To display a description of the contents of the current syntax table, type `C-h s' (`describe-syntax'). The description of each character includes both the string you would have to give to `modify-syntax-entry' to set up that character's current syntax, and some English to explain that string if necessary. For full information on the syntax table, see *Note Syntax Tables: (elisp)Syntax Tables. File: emacs, Node: Init File, Prev: Syntax, Up: Customization The Init File, `~/.emacs' ========================= When Emacs is started, it normally loads a Lisp program from the file `.emacs' in your home directory. We call this file your "init file" because it specifies how to initialize Emacs for you. You can use the command line switches `-q' and `-u' to tell Emacs whether to load an init file, and which one (*note Entering Emacs::.). There can also be a "default init file", which is the library named `default.el', found via the standard search path for libraries. The Emacs distribution contains no such library; your site may create one for local customizations. If this library exists, it is loaded whenever you start Emacs (except when you specify `-q'). But your init file, if any, is loaded first; if it sets `inhibit-default-init' non-`nil', then `default' is not loaded. Your site may also have a "site startup file"; this is named `site-start.el', if it exists. Emacs loads this library before it loads your init file. To inhibit loading of this library, use the option `-no-site-file'. If you have a large amount of code in your `.emacs' file, you should move it into another file such as `~/SOMETHING.el', byte-compile it, and make your `.emacs' file load it with `(load "~/SOMETHING")'. *Note Byte Compilation: (elisp)Byte Compilation, for more information about compiling Emacs Lisp programs. * Menu: * Init Syntax:: Syntax of constants in Emacs Lisp. * Init Examples:: How to do some things with an init file. * Terminal Init:: Each terminal type can have an init file. * Find Init:: How Emacs finds the init file. File: emacs, Node: Init Syntax, Next: Init Examples, Up: Init File Init File Syntax ---------------- The `.emacs' file contains one or more Lisp function call expressions. Each of these consists of a function name followed by arguments, all surrounded by parentheses. For example, `(setq fill-column 60)' calls the function `setq' to set the variable `fill-column' (*note Filling::.) to 60. The second argument to `setq' is an expression for the new value of the variable. This can be a constant, a variable, or a function call expression. In `.emacs', constants are used most of the time. They can be: Numbers: Numbers are written in decimal, with an optional initial minus sign. Strings: Lisp string syntax is the same as C string syntax with a few extra features. Use a double-quote character to begin and end a string constant. In a string, you can include newlines and special characters literally. But often it is cleaner to use backslash sequences for them: `\n' for newline, `\b' for backspace, `\r' for carriage return, `\t' for tab, `\f' for formfeed (control-L), `\e' for escape, `\\' for a backslash, `\"' for a double-quote, or `\OOO' for the character whose octal code is OOO. Backslash and double-quote are the only characters for which backslash sequences are mandatory. `\C-' can be used as a prefix for a control character, as in `\C-s' for ASCII control-S, and `\M-' can be used as a prefix for a Meta character, as in `\M-a' for `Meta-A' or `\M-\C-a' for `Control-Meta-A'. Characters: Lisp character constant syntax consists of a `?' followed by either a character or an escape sequence starting with `\'. Examples: `?x', `?\n', `?\"', `?\)'. Note that strings and characters are not interchangeable in Lisp; some contexts require one and some contexts require the other. True: `t' stands for `true'. False: `nil' stands for `false'. Other Lisp objects: Write a single-quote (') followed by the Lisp object you want. File: emacs, Node: Init Examples, Next: Terminal Init, Prev: Init Syntax, Up: Init File Init File Examples ------------------ Here are some examples of doing certain commonly desired things with Lisp expressions: * Make TAB in C mode just insert a tab if point is in the middle of a line. (setq c-tab-always-indent nil) Here we have a variable whose value is normally `t' for `true' and the alternative is `nil' for `false'. * Make searches case sensitive by default (in all buffers that do not override this). (setq-default case-fold-search nil) This sets the default value, which is effective in all buffers that do not have local values for the variable. Setting `case-fold-search' with `setq' affects only the current buffer's local value, which is not what you probably want to do in an init file. * Specify your own email address, if Emacs can't figure it out correctly. (setq user-mail-address "coon@yoyodyne.com") Various Emacs packages that need your own email address use the value of `user-mail-address'. * Make Text mode the default mode for new buffers. (setq default-major-mode 'text-mode) Note that `text-mode' is used because it is the command for entering Text mode. The single-quote before it makes the symbol a constant; otherwise, `text-mode' would be treated as a variable name. * Turn on Auto Fill mode automatically in Text mode and related modes. (add-hook 'text-mode-hook '(lambda () (auto-fill-mode 1))) This shows how to add a hook function to a normal hook variable (*note Hooks::.). The function we supply is a list starting with `lambda', with a single-quote in front of it to make it a list constant rather than an expression. It's beyond the scope of this manual to explain Lisp functions, but for this example it is enough to know that the effect is to execute `(auto-fill-mode 1)' when Text mode is entered. You can replace that with any other expression that you like, or with several expressions in a row. Emacs comes with a function named `turn-on-auto-fill' whose definition is `(lambda () (auto-fill-mode 1))'. Thus, a simpler way to write the above example is as follows: (add-hook 'text-mode-hook 'turn-on-auto-fill) * Load the installed Lisp library named `foo' (actually a file `foo.elc' or `foo.el' in a standard Emacs directory). (load "foo") When the argument to `load' is a relative file name, not starting with `/' or `~', `load' searches the directories in `load-path' (*note Lisp Libraries::.). * Load the compiled Lisp file `foo.elc' from your home directory. (load "~/foo.elc") Here an absolute file name is used, so no searching is done. * Rebind the key `C-x l' to run the function `make-symbolic-link'. (global-set-key "\C-xl" 'make-symbolic-link) or (define-key global-map "\C-xl" 'make-symbolic-link) Note once again the single-quote used to refer to the symbol `make-symbolic-link' instead of its value as a variable. * Do the same thing for C mode only. (define-key c-mode-map "\C-xl" 'make-symbolic-link) * Redefine all keys which now run `next-line' in Fundamental mode so that they run `forward-line' instead. (substitute-key-definition 'next-line 'forward-line global-map) * Make `C-x C-v' undefined. (global-unset-key "\C-x\C-v") One reason to undefine a key is so that you can make it a prefix. Simply defining `C-x C-v ANYTHING' will make `C-x C-v' a prefix, but `C-x C-v' must first be freed of its usual non-prefix definition. * Make `$' have the syntax of punctuation in Text mode. Note the use of a character constant for `$'. (modify-syntax-entry ?\$ "." text-mode-syntax-table) * Enable the use of the command `eval-expression' without confirmation. (put 'eval-expression 'disabled nil) File: emacs, Node: Terminal Init, Next: Find Init, Prev: Init Examples, Up: Init File Terminal-specific Initialization -------------------------------- Each terminal type can have a Lisp library to be loaded into Emacs when it is run on that type of terminal. For a terminal type named TERMTYPE, the library is called `term/TERMTYPE' and it is found by searching the directories `load-path' as usual and trying the suffixes `.elc' and `.el'. Normally it appears in the subdirectory `term' of the directory where most Emacs libraries are kept. The usual purpose of the terminal-specific library is to map the escape sequences used by the terminal's function keys onto more meaningful names, using `function-key-map'. See the file `term/lk201.el' for an example of how this is done. Many function keys are mapped automatically according to the information in the Termcap data base; the terminal-specific library needs to map only the function keys that Termcap does not specify. When the terminal type contains a hyphen, only the part of the name before the first hyphen is significant in choosing the library name. Thus, terminal types `aaa-48' and `aaa-30-rv' both use the library `term/aaa'. The code in the library can use `(getenv "TERM")' to find the full terminal type name. The library's name is constructed by concatenating the value of the variable `term-file-prefix' and the terminal type. Your `.emacs' file can prevent the loading of the terminal-specific library by setting `term-file-prefix' to `nil'. Emacs runs the hook `term-setup-hook' at the end of initialization, after both your `.emacs' file and any terminal-specific library have been read in. Add hook functions to this hook if you wish to override part of any of the terminal-specific libraries and to define initializations for terminals that do not have a library. *Note Hooks::. File: emacs, Node: Find Init, Prev: Terminal Init, Up: Init File How Emacs Finds Your Init File ------------------------------ Normally Emacs uses the environment variable `HOME' to find `.emacs'; that's what `~' means in a file name. But if you have done `su', Emacs tries to find your own `.emacs', not that of the user you are currently pretending to be. The idea is that you should get your own editor customizations even if you are running as the super user. More precisely, Emacs first determines which user's init file to use. It gets the user name from the environment variables `LOGNAME' and `USER'; if neither of those exists, it uses effective user-ID. If that user name matches the real user-ID, then Emacs uses `HOME'; otherwise, it looks up the home directory corresponding to that user name in the system's data base of users. File: emacs, Node: Quitting, Next: Lossage, Prev: Customization, Up: Top Quitting and Aborting ===================== `C-g' Quit. Cancel running or partially typed command. `C-]' Abort innermost recursive editing level and cancel the command which invoked it (`abort-recursive-edit'). `ESC ESC ESC' Either quit or abort, whichever makes sense (`keyboard-escape-quit'). `M-x top-level' Abort all recursive editing levels that are currently executing. `C-x u' Cancel a previously made change in the buffer contents (`undo'). There are two ways of canceling commands which are not finished executing: "quitting" with `C-g', and "aborting" with `C-]' or `M-x top-level'. Quitting cancels a partially typed command or one which is already running. Aborting exits a recursive editing level and cancels the command that invoked the recursive edit. (*Note Recursive Edit::.) Quitting with `C-g' is used for getting rid of a partially typed command, or a numeric argument that you don't want. It also stops a running command in the middle in a relatively safe way, so you can use it if you accidentally give a command which takes a long time. In particular, it is safe to quit out of killing; either your text will *all* still be in the buffer, or it will *all* be in the kill ring (or maybe both). Quitting an incremental search does special things documented under searching; in general, it may take two successive `C-g' characters to get out of a search (*note Incremental Search::.). `C-g' works by setting the variable `quit-flag' to `t' the instant `C-g' is typed; Emacs Lisp checks this variable frequently and quits if it is non-`nil'. `C-g' is only actually executed as a command if you type it while Emacs is waiting for input. If you quit with `C-g' a second time before the first `C-g' is recognized, you activate the "emergency escape" feature and return to the shell. *Note Emergency Escape::. There may be times when you cannot quit. When Emacs is waiting for the operating system to do something, quitting is impossible unless special pains are taken for the particular system call within Emacs where the waiting occurs. We have done this for the system calls that users are likely to want to quit from, but it's possible you will find another. In one very common case--waiting for file input or output using NFS--Emacs itself knows how to quit, but most NFS implementations simply do not allow user programs to stop waiting for NFS when the NFS server is hung. Aborting with `C-]' (`abort-recursive-edit') is used to get out of a recursive editing level and cancel the command which invoked it. Quitting with `C-g' does not do this, and could not do this, because it is used to cancel a partially typed command *within* the recursive editing level. Both operations are useful. For example, if you are in a recursive edit and type `C-u 8' to enter a numeric argument, you can cancel that argument with `C-g' and remain in the recursive edit. The command `ESC ESC ESC' (`keyboard-escape-quit') can either quit or abort. This key was defined because ESC is used to "get out" in many PC programs. It can cancel a prefix argument, clear a selected region, or get out of a Query Replace, like `C-g'. It can get out of the minibuffer or a recursive edit, like `C-]'. It can also get out of splitting the frame into multiple windows, like `C-x 1'. One thing it cannot do, however, is stop a command that is running. That's because it executes as an ordinary command, and Emacs doesn't notice it until it is ready for a command. The command `M-x top-level' is equivalent to "enough" `C-]' commands to get you out of all the levels of recursive edits that you are in. `C-]' gets you out one level at a time, but `M-x top-level' goes out all levels at once. Both `C-]' and `M-x top-level' are like all other commands, and unlike `C-g', in that they take effect only when Emacs is ready for a command. `C-]' is an ordinary key and has its meaning only because of its binding in the keymap. *Note Recursive Edit::. `C-x u' (`undo') is not strictly speaking a way of canceling a command, but you can think of it as canceling a command that already finished executing. *Note Undo::. File: emacs, Node: Lossage, Next: Bugs, Prev: Quitting, Up: Top Dealing with Emacs Trouble ========================== This section describes various conditions in which Emacs fails to work normally, and how to recognize them and correct them. * Menu: * DEL Gets Help:: What to do if DEL doesn't delete. * Stuck Recursive:: `[...]' in mode line around the parentheses. * Screen Garbled:: Garbage on the screen. * Text Garbled:: Garbage in the text. * Unasked-for Search:: Spontaneous entry to incremental search. * Memory Full:: How to cope when you run out of memory. * Emergency Escape:: Emergency escape-- What to do if Emacs stops responding. * Total Frustration:: When you are at your wits' end. File: emacs, Node: DEL Gets Help, Next: Stuck Recursive, Up: Lossage If DEL Fails to Delete ---------------------- If you find that DEL enters Help like `Control-h' instead of deleting a character, your terminal is sending the wrong code for DEL. You can work around this problem by changing the keyboard translation table (*note Keyboard Translations::.). File: emacs, Node: Stuck Recursive, Next: Screen Garbled, Prev: DEL Gets Help, Up: Lossage Recursive Editing Levels ------------------------ Recursive editing levels are important and useful features of Emacs, but they can seem like malfunctions to the user who does not understand them. If the mode line has square brackets `[...]' around the parentheses that contain the names of the major and minor modes, you have entered a recursive editing level. If you did not do this on purpose, or if you don't understand what that means, you should just get out of the recursive editing level. To do so, type `M-x top-level'. This is called getting back to top level. *Note Recursive Edit::. File: emacs, Node: Screen Garbled, Next: Text Garbled, Prev: Stuck Recursive, Up: Lossage Garbage on the Screen --------------------- If the data on the screen looks wrong, the first thing to do is see whether the text is really wrong. Type `C-l', to redisplay the entire screen. If the screen appears correct after this, the problem was entirely in the previous screen update. (Otherwise, see *Note Text Garbled::.) Display updating problems often result from an incorrect termcap entry for the terminal you are using. The file `etc/TERMS' in the Emacs distribution gives the fixes for known problems of this sort. `INSTALL' contains general advice for these problems in one of its sections. Very likely there is simply insufficient padding for certain display operations. To investigate the possibility that you have this sort of problem, try Emacs on another terminal made by a different manufacturer. If problems happen frequently on one kind of terminal but not another kind, it is likely to be a bad termcap entry, though it could also be due to a bug in Emacs that appears for terminals that have or that lack specific features. File: emacs, Node: Text Garbled, Next: Unasked-for Search, Prev: Screen Garbled, Up: Lossage Garbage in the Text ------------------- If `C-l' shows that the text is wrong, try undoing the changes to it using `C-x u' until it gets back to a state you consider correct. Also try `C-h l' to find out what command you typed to produce the observed results. If a large portion of text appears to be missing at the beginning or end of the buffer, check for the word `Narrow' in the mode line. If it appears, the text you don't see is probably still present, but temporarily off-limits. To make it accessible again, type `C-x n w'. *Note Narrowing::. File: emacs, Node: Unasked-for Search, Next: Memory Full, Prev: Text Garbled, Up: Lossage Spontaneous Entry to Incremental Search --------------------------------------- If Emacs spontaneously displays `I-search:' at the bottom of the screen, it means that the terminal is sending `C-s' and `C-q' according to the poorly designed xon/xoff "flow control" protocol. If this happens to you, your best recourse is to put the terminal in a mode where it will not use flow control, or give it so much padding that it will never send a `C-s'. (One way to increase the amount of padding is to set the variable `baud-rate' to a larger value. Its value is the terminal output speed, measured in the conventional units of baud.) If you don't succeed in turning off flow control, the next best thing is to tell Emacs to cope with it. To do this, call the function `enable-flow-control'. Typically there are particular terminal types with which you must use flow control. You can conveniently ask for flow control on those terminal types only, using `enable-flow-control-on'. For example, if you find you must use flow control on VT-100 and H19 terminals, put the following in your `.emacs' file: (enable-flow-control-on "vt100" "h19") When flow control is enabled, you must type `C-\' to get the effect of a `C-s', and type `C-^' to get the effect of a `C-q'. (These aliases work by means of keyboard translations; see *Note Keyboard Translations::.) File: emacs, Node: Memory Full, Next: Emergency Escape, Prev: Unasked-for Search, Up: Lossage Running out of Memory --------------------- If you get the error message `Virtual memory exceeded', save your modified buffers with `C-x s'. This method of saving them has the smallest need for additional memory. Emacs keeps a reserve of memory which it makes available when this error happens; that should be enough to enable `C-x s' to complete its work. Once you have saved your modified buffers, you can exit this Emacs job and start another, or you can use `M-x kill-some-buffers' to free space in the current Emacs job. If you kill buffers containing a substantial amount of text, you can safely go on editing. Emacs refills its memory reserve automatically when it sees sufficient free space available, in case you run out of memory another time. Do not use `M-x buffer-menu' to save or kill buffers when you run out of memory, because the buffer menu needs a fair amount memory itself, and the reserve supply may not be enough. File: emacs, Node: Emergency Escape, Next: Total Frustration, Prev: Memory Full, Up: Lossage Emergency Escape ---------------- Because at times there have been bugs causing Emacs to loop without checking `quit-flag', a special feature causes Emacs to be suspended immediately if you type a second `C-g' while the flag is already set, so you can always get out of GNU Emacs. Normally Emacs recognizes and clears `quit-flag' (and quits!) quickly enough to prevent this from happening. When you resume Emacs after a suspension caused by multiple `C-g', it asks two questions before going back to what it had been doing: Auto-save? (y or n) Abort (and dump core)? (y or n) Answer each one with `y' or `n' followed by RET. Saying `y' to `Auto-save?' causes immediate auto-saving of all modified buffers in which auto-saving is enabled. Saying `y' to `Abort (and dump core)?' causes an illegal instruction to be executed, dumping core. This is to enable a wizard to figure out why Emacs was failing to quit in the first place. Execution does not continue after a core dump. If you answer `n', execution does continue. With luck, GNU Emacs will ultimately check `quit-flag' and quit normally. If not, and you type another `C-g', it is suspended again. If Emacs is not really hung, just slow, you may invoke the double `C-g' feature without really meaning to. Then just resume and answer `n' to both questions, and you will arrive at your former state. Presumably the quit you requested will happen soon. The double-`C-g' feature is turned off when Emacs is running under the X Window System, since you can use the window manager to kill Emacs or to create another window and run another program. File: emacs, Node: Total Frustration, Prev: Emergency Escape, Up: Lossage Help for Total Frustration -------------------------- If using Emacs (or something else) becomes terribly frustrating and none of the techniques described above solve the problem, Emacs can still help you. First, if the Emacs you are using is not responding to commands, type `C-g C-g' to get out of it and then start a new one. Second, type `M-x doctor RET'. The doctor will help you feel better. Each time you say something to the doctor, you must end it by typing RET RET. This lets the doctor know you are finished. File: emacs, Node: Bugs, Next: Service, Prev: Lossage, Up: Top Reporting Bugs ============== Sometimes you will encounter a bug in Emacs. Although we cannot promise we can or will fix the bug, and we might not even agree that it is a bug, we want to hear about problems you encounter. Often we agree they are bugs and want to fix them. To make it possible for us to fix a bug, you must report it. In order to do so effectively, you must know when and how to do it. * Menu: * Criteria: Bug Criteria. Have you really found a bug? * Understanding Bug Reporting:: How to report a bug effectively. * Checklist:: Steps to follow for a good bug report. * Sending Patches:: How to send a patch for GNU Emacs. File: emacs, Node: Bug Criteria, Next: Understanding Bug Reporting, Up: Bugs When Is There a Bug ------------------- If Emacs executes an illegal instruction, or dies with an operating system error message that indicates a problem in the program (as opposed to something like "disk full"), then it is certainly a bug. If Emacs updates the display in a way that does not correspond to what is in the buffer, then it is certainly a bug. If a command seems to do the wrong thing but the problem corrects itself if you type `C-l', it is a case of incorrect display updating. Taking forever to complete a command can be a bug, but you must make certain that it was really Emacs's fault. Some commands simply take a long time. Type `C-g' and then `C-h l' to see whether the input Emacs received was what you intended to type; if the input was such that you *know* it should have been processed quickly, report a bug. If you don't know whether the command should take a long time, find out by looking in the manual or by asking for assistance. If a command you are familiar with causes an Emacs error message in a case where its usual definition ought to be reasonable, it is probably a bug. If a command does the wrong thing, that is a bug. But be sure you know for certain what it ought to have done. If you aren't familiar with the command, or don't know for certain how the command is supposed to work, then it might actually be working right. Rather than jumping to conclusions, show the problem to someone who knows for certain. Finally, a command's intended definition may not be best for editing with. This is a very important sort of problem, but it is also a matter of judgment. Also, it is easy to come to such a conclusion out of ignorance of some of the existing features. It is probably best not to complain about such a problem until you have checked the documentation in the usual ways, feel confident that you understand it, and know for certain that what you want is not available. If you are not sure what the command is supposed to do after a careful reading of the manual, check the index and glossary for any terms that may be unclear. If after careful rereading of the manual you still do not understand what the command should do, that indicates a bug in the manual, which you should report. The manual's job is to make everything clear to people who are not Emacs experts--including you. It is just as important to report documentation bugs as program bugs. If the on-line documentation string of a function or variable disagrees with the manual, one of them must be wrong; that is a bug. File: emacs, Node: Understanding Bug Reporting, Next: Checklist, Prev: Bug Criteria, Up: Bugs Understanding Bug Reporting --------------------------- When you decide that there is a bug, it is important to report it and to report it in a way which is useful. What is most useful is an exact description of what commands you type, starting with the shell command to run Emacs, until the problem happens. The most important principle in reporting a bug is to report *facts*, not hypotheses or categorizations. It is always easier to report the facts, but people seem to prefer to strain to posit explanations and report them instead. If the explanations are based on guesses about how Emacs is implemented, they will be useless; we will have to try to figure out what the facts must have been to lead to such speculations. Sometimes this is impossible. But in any case, it is unnecessary work for us. For example, suppose that you type `C-x C-f /glorp/baz.ugh RET', visiting a file which (you know) happens to be rather large, and Emacs prints out `I feel pretty today'. The best way to report the bug is with a sentence like the preceding one, because it gives all the facts and nothing but the facts. Do not assume that the problem is due to the size of the file and say, "When I visit a large file, Emacs prints out `I feel pretty today'." This is what we mean by "guessing explanations". The problem is just as likely to be due to the fact that there is a `z' in the file name. If this is so, then when we got your report, we would try out the problem with some "large file", probably with no `z' in its name, and not find anything wrong. There is no way in the world that we could guess that we should try visiting a file with a `z' in its name. Alternatively, the problem might be due to the fact that the file starts with exactly 25 spaces. For this reason, you should make sure that you inform us of the exact contents of any file that is needed to reproduce the bug. What if the problem only occurs when you have typed the `C-x C-a' command previously? This is why we ask you to give the exact sequence of characters you typed since starting the Emacs session. You should not even say "visit a file" instead of `C-x C-f' unless you *know* that it makes no difference which visiting command is used. Similarly, rather than saying "if I have three characters on the line," say "after I type `RET A B C RET C-p'," if that is the way you entered the text.