SGI Developer Toolbox 6.1

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

/ SGI Developer Toolbox 6.1 / SGI Developer Toolbox 6.1 - Disc 4.iso / public / GNU / emacs.inst / emacs19.idb / usr / gnu / info / emacs-17.z / emacs-17

Wrap

GNU Info File | 1994-08-02 | 48.3 KB | 1,138 lines

This is Info file ../info/emacs, produced by Makeinfo-1.54 from the input file emacs.texi. 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. Attempting to invoke a disabled command interactively in Emacs causes the display of 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, or cancel it. 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 have 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 "Text deleted this way cannot be yanked back!\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; it 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. 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 Table: (elisp)Syntax Table. 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. 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. * 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 it 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 define the escape sequences used by the terminal's function keys using the library `keypad.el'. See the file `term/vt100.el' for an example of how this is done. 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 `USER' and `LOGNAME'; 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'). `M-x top-level' Abort all recursive editing levels that are currently executing. `C-x u' Cancel an already-executed command, usually (`undo'). There are two ways of cancelling 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. `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 `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 are effective 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 cancelling a command, but you can think of it as cancelling a command 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. * 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. 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 is 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: Emergency Escape, 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: Emergency Escape, Next: Total Frustration, Prev: Unasked-for Search, 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 the 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 bugs you encounter in case we do 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 you still do not understand, 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 to use Emacs. 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. File: emacs, Node: Checklist, Next: Sending Patches, Prev: Understanding Bug Reporting, Up: Bugs Checklist for Bug Reports ------------------------- The best way to send a bug report is to mail it electronically to the Emacs maintainers at `bug-gnu-emacs@prep.ai.mit.edu'. If you'd like to read the bug reports, you can find them on the repeater newsgroup `gnu.emacs.bugs'; keep in mind, however, that as a spectator you should not criticize anything about what you see there. The purpose of bug reports is to give information to the Emacs maintainers. Spectators are welcome only as long as they do not interfere with this. Please do not post bug reports using netnews; mail is more reliable than netnews about reporting your correct address, which we may need in order to ask you for more information. If you can't send electronic mail, then mail the bug report on paper to this address: GNU Emacs Bugs Free Software Foundation 675 Mass Ave Cambridge, MA 02139 We do not promise to fix the bug; but if the bug is serious, or ugly, or easy to fix, chances are we will want to. To enable maintainers to investigate a bug, your report should include all these things: * The version number of Emacs. Without this, we won't know whether there is any point in looking for the bug in the current version of GNU Emacs. You can get the version number by typing `M-x emacs-version RET'. If that command does not work, you probably have something other than GNU Emacs, so you will have to report the bug somewhere else. * The type of machine you are using, and the operating system name and version number. * The operands you gave to the `configure' command when you installed Emacs. * A complete list of any modifications you have made to the Emacs source. (We may not have time to investigate the bug unless it happens in an unmodified Emacs. But if you've made modifications and don't tell us, then you are sending us on a wild goose chase.) Be precise about these changes. A description in English is not enough--send a context diff for them. Adding files of your own (such as a machine description for a machine we don't support) is a modification of the source. * Details of any other deviations from the standard procedure for installing GNU Emacs. * The complete text of any files needed to reproduce the bug. If you can tell us a way to cause the problem without visiting any files, please do so. This makes it much easier to debug. If you do need files, make sure you arrange for us to see their exact contents. For example, it can often matter whether there are spaces at the ends of lines, or a newline after the last line in the buffer (nothing ought to care whether the last line is terminated, but try telling the bugs that). * The precise commands we need to type to reproduce the bug. The easy way to record the input to Emacs precisely is to to write a dribble file. To start the file, execute the Lisp expression (open-dribble-file "~/dribble") using `M-ESC' or from the `*scratch*' buffer just after starting Emacs. From then on, Emacs copies all your input to the specified dribble file until the Emacs process is killed. * For possible display bugs, the terminal type (the value of environment variable `TERM'), the complete termcap entry for the terminal from `/etc/termcap' (since that file is not identical on all machines), and the output that Emacs actually sent to the terminal. The way to collect the terminal output is to execute the Lisp expression (open-termscript "~/termscript") using `M-ESC' or from the `*scratch*' buffer just after starting Emacs. From then on, Emacs copies all terminal output to the specified termscript file as well, until the Emacs process is killed. If the problem happens when Emacs starts up, put this expression into your `.emacs' file so that the termscript file will be open when Emacs displays the screen for the first time. Be warned: it is often difficult, and sometimes impossible, to fix a terminal-dependent bug without access to a terminal of the type that stimulates the bug. * A description of what behavior you observe that you believe is incorrect. For example, "The Emacs process gets a fatal signal," or, "The resulting text is as follows, which I think is wrong." Of course, if the bug is that Emacs gets a fatal signal, then one can't miss it. But if the bug is incorrect text, the maintainer might fail to notice what is wrong. Why leave it to chance? Even if the problem you experience is a fatal signal, you should still say so explicitly. Suppose something strange is going on, such as, your copy of the source is out of sync, or you have encountered a bug in the C library on your system. (This has happened!) Your copy might crash and the copy here would not. If you *said* to expect a crash, then when Emacs here fails to crash, we would know that the bug was not happening. If you don't say to expect a crash, then we would not know whether the bug was happening. We would not be able to draw any conclusion from our observations. If the manifestation of the bug is an Emacs error message, it is important to report not just the text of the error message but a backtrace showing how the Lisp program in Emacs arrived at the error. To make the backtrace, execute the Lisp expression `(setq debug-on-error t)' before the error happens (that is to say, you must execute that expression and then make the bug happen). This causes the Lisp debugger to run, showing you a backtrace. Copy the text of the debugger's backtrace into the bug report. This use of the debugger is possible only if you know how to make the bug happen again. Do note the error message the first time the bug happens, so if you can't make it happen again, you can report at least the error message. * Check whether any programs you have loaded into the Lisp world, including your `.emacs' file, set any variables that may affect the functioning of Emacs. Also, see whether the problem happens in a freshly started Emacs without loading your `.emacs' file (start Emacs with the `-q' switch to prevent loading the init file.) If the problem does *not* occur then, you must report the precise contents of any programs that you must load into the Lisp world in order to cause the problem to occur. * If the problem does depend on an init file or other Lisp programs that are not part of the standard Emacs system, then you should make sure it is not a bug in those programs by complaining to their maintainers first. After they verify that they are using Emacs in a way that is supposed to work, they should report the bug. * If you wish to mention something in the GNU Emacs source, show the portion in its context. Don't just give a line number. The line numbers in the development sources don't match those in your sources. It would take extra work for the maintainers to determine what code is in your version at a given line number, and we could not be certain. * Additional information from a debugger might enable someone to find a problem on a machine which he does not have available. However, you need to think when you collect this information if you want it to be useful. For example, many people send just a backtrace, but that is never useful by itself. A simple backtrace with arguments conveys little about what is happening inside GNU Emacs, because most of the arguments listed in the backtrace are pointers to Lisp objects. The numeric values of these pointers have no significance whatever; all that matters is the contents of the objects they point to (and most of the contents are themselves pointers). To provide useful information, you need to show the values of Lisp objects in Lisp notation. Do this for each variable which is a Lisp object, in several stack frames near the bottom of the stack. Look at the source to see which variables are Lisp objects, because the debugger thinks of them as integers. To show a variable's value in Lisp syntax, first print its value, then use the GDB command `pr' to print the Lisp object in Lisp syntax. (If you must use another debugger, call the function `debug_print' with the object as an argument.) The `pr' command is defined by the file `src/.gdbinit' in the Emacs distribution, and it works only if you are debugging a running process (not with a core dump). Here are some things that are not necessary: * A description of the envelope of the bug--this is not necessary for a reproducible bug. Often people who encounter a bug spend a lot of time investigating which changes to the input file will make the bug go away and which changes will not affect it. This is often time consuming and not very useful, because the way we will find the bug is by running a single example under the debugger with breakpoints, not by pure deduction from a series of examples. You might as well save time by not doing this. Of course, if you can find a simpler example to report *instead* of the original one, that is a convenience. Errors in the output will be easier to spot, running under the debugger will take less time, etc. However, simplification is not vital; if you don't want to do this, please report the bug with your original test case. * A patch for the bug. A patch for the bug is useful if it is a good one. But don't omit the necessary information, such as the test case, on the assumption that a patch is all we need. We might see problems with your patch and decide to fix the problem another way, or we might not understand it at all. And if we can't understand what bug you are trying to fix, or why your patch should be an improvement, we mustn't install it. A test case will help us to understand. *Note Sending Patches::, for guidelines on how to make it easy for us to understand and install your patches. * A guess about what the bug is or what it depends on. Such guesses are usually wrong. Even experts can't guess right about such things without first using the debugger to find the facts. File: emacs, Node: Sending Patches, Prev: Checklist, Up: Bugs Sending Patches for GNU Emacs ----------------------------- If you would like to write bug fixes or improvements for GNU Emacs, that is very helpful. When you send your changes, please follow these guidelines to make it easy for the maintainers to use them. If you don't follow these guidelines, your information might still be useful, but using it will take extra work. Maintaining GNU Emacs is a lot of work in the best of circumstances, and we can't keep up unless you do your best to help. * Send an explanation with your changes of what problem they fix or what improvement they bring about. For a bug fix, just include a copy of the bug report, and explain why the change fixes the bug. (Referring to a bug report is not as good as including it, because then we will have to look it up, and we have probably already deleted it if we've already fixed the bug.) * Always include a proper bug report for the problem you think you have fixed. We need to convince ourselves that the change is right before installing it. Even if it is correct, we might have trouble understanding it if we don't have a way to reproduce the problem. * Include all the comments that are appropriate to help people reading the source in the future understand why this change was needed. * Don't mix together changes made for different reasons. Send them *individually*. If you make two changes for separate reasons, then we might not want to install them both. We might want to install just one. If you send them all jumbled together in a single set of diffs, we have to do extra work to disentangle them--to figure out which parts of the change serve which purpose. If we don't have time for this, we might have to ignore your changes entirely. If you send each change as soon as you have written it, with its own explanation, then the two changes never get tangled up, and we can consider each one properly without any extra work to disentangle them. * Send each change as soon as that change is finished. Sometimes people think they are helping us by accumulating many changes to send them all together. As explained above, this is absolutely the worst thing you could do. Since you should send each change separately, you might as well send it right away. That gives us the option of installing it immediately if it is important. * Use `diff -c' to make your diffs. Diffs without context are hard to install reliably. More than that, they are hard to study; we must always study a patch to decide whether we want to install it. Unidiff format is better than contextless diffs, but not as easy to read as `-c' format. If you have GNU diff, use `diff -cp', which shows the name of the function that each change occurs in. * Write the change log entries for your changes. This is both to save us the extra work of writing them, and to help explain your changes so we can understand them. The purpose of the change log is to show people where to find what was changed. So you need to be specific about what functions you changed; in large functions, it's often helpful to indicate where within the function the change was. On the other hand, once you have shown people where to find the change, you need not explain its purpose. Thus, if you add a new function, all you need to say about it is that it is new. If you feel that the purpose needs explaining, it probably does--but the explanation will be much more useful if you put it in comments in the code. Please read the `ChangeLog' file to see what sorts of information to put in, and to learn the style that we use. If you would like your name to appear in the header line showing who made the change, send us the header line. * When you write the fix, keep in mind that we can't install a change that would break other systems. Please think about what effect your change will have if compiled on another type of system. Sometimes people send fixes that *might* be an improvement in general--but it is hard to be sure of this. It's hard to install such changes because we have to study them very carefully. Of course, a good explanation of the reasoning by which you concluded the change was correct can help convince us. The safest changes are changes to the configuration files for a particular machine. These are safe because they can't create new bugs on other machines. Please help us keep up with the workload by designing the patch in a form that is clearly safe to install. File: emacs, Node: Service, Next: Command Arguments, Prev: Bugs, Up: Top How To Get Help with GNU Emacs ============================== If you need help installing, using or changing GNU Emacs, there are two ways to find it: * Send a message to a suitable network mailing list. First try `bug-gnu-emacs@prep.ai.mit.edu', and if that brings no response, try `help-gnu-emacs@prep.ai.mit.edu'. * Look in the service directory for someone who might help you for a fee. The service directory is found in the file named `etc/SERVICE' in the Emacs distribution. File: emacs, Node: Command Arguments, Next: Antinews, Prev: Service, Up: Top Command Line Options and Arguments ********************************** GNU Emacs supports command line arguments to request various actions when invoking Emacs. These are for compatibility with other editors and for sophisticated activities. We don't recommend using them for ordinary editing. Arguments that are not options specify files to visit. Emacs visits the specified files while it starts up. (The last file name on your command line is the one you see displayed, but the rest are all there in other buffers.) You can use options to specify other things, such as the size and position of the Emacs window if you are running it under the X Window System. A few arguments support advanced usage, like running Lisp functions on files in batch mode. There are two kinds of options: "ordinary options" and "initial options". Ordinary options can appear in any order and can be intermixed with file names to visit. These and file names are called "ordinary arguments". Emacs processes all of these in the order they are written. Initial options must come at the beginning of the command line. * Menu: * Ordinary Arguments:: Arguments to visit files, load libraries, and call functions. * Initial Options:: Arguments that must come at the start of the command. * Command Example:: Examples of using command line arguments. * Resume Arguments:: Specifying arguments when you resume a running Emacs. * Display X:: Changing the default display and using remote login. * Font X:: Choosing a font for text, under X. * Colors X:: Choosing colors, under X. * Window Size X:: Start-up window size, under X. * Borders X:: Internal and external borders, under X. * Icons X:: Choosing what sort of icon to use, under X. * Resources X:: Advanced use of classes and resources, under X.