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GNU Info File | 1995-09-11 | 44.7 KB | 1,071 lines

This is Info file ../info/emacs, produced by Makeinfo-1.55 from the input file emacs.texi. File: emacs, Node: Commands of GUD, Next: GUD Customization, Prev: Debugger Operation, Up: Debuggers Commands of GUD --------------- The GUD interaction buffer uses a variant of Shell mode, so the commands of Shell mode are available (*note Shell Mode::.). GUD mode also provides commands for setting and clearing breakpoints, for selecting stack frames, and for stepping through the program. These commands are available both in the GUD buffer and globally, but with different key bindings. The breakpoint commands are usually used in source file buffers, because that is the way to specify where to set or clear the breakpoint. Here's the global command to set a breakpoint: `C-x SPC' Set a breakpoint on the source line that point is on. Here are the other special commands provided by GUD. The keys starting with `C-c' are available only in the GUD interaction buffer. The bindings that start with `C-x C-a' are available in the GUD buffer and also in source files. `C-c C-l' `C-x C-a C-l' Display in another window the last line referred to in the GUD buffer (that is, the line indicated in the last location message). This runs the command `gud-refresh'. `C-c C-s' `C-x C-a C-s' Execute a single line of code (`gud-step'). If the line contains a function call, execution stops after entering the called function. `C-c C-n' `C-x C-a C-n' Execute a single line of code, stepping across entire function calls at full speed (`gud-next'). `C-c C-i' `C-x C-a C-i' Execute a single machine instruction (`gud-stepi'). `C-c C-r' `C-x C-a C-r' Continue execution without specifying any stopping point. The program will run until it hits a breakpoint, terminates, or gets a signal that the debugger is checking for (`gud-cont'). `C-c C-d' `C-x C-a C-d' Delete the breakpoint(s) on the current source line, if any (`gud-remove'). If you use this command in the GUD interaction buffer, it applies to the line where the program last stopped. `C-c C-t' `C-x C-a C-t' Set a temporary breakpoint on the current source line, if any. If you use this command in the GUD interaction buffer, it applies to the line where the program last stopped. The above commands are common to all supported debuggers. If you are using GDB or (some versions of) DBX, these additional commands are available: `C-c <' `C-x C-a <' Select the next enclosing stack frame (`gud-up'). This is equivalent to the `up' command. `C-c >' `C-x C-a >' Select the next inner stack frame (`gud-down'). This is equivalent to the `down' command. If you are using GDB, these additional key bindings are available: `TAB' With GDB, complete a symbol name (`gud-gdb-complete-command'). This key is available only in the GUD interaction buffer, and requires GDB versions 4.13 and later. `C-c C-f' `C-x C-a C-f' Run the program until the selected stack frame returns (or until it stops for some other reason). These commands interpret a numeric argument as a repeat count, when that makes sense. File: emacs, Node: GUD Customization, Prev: Commands of GUD, Up: Debuggers GUD Customization ----------------- On startup, GUD runs one of the following hooks: `gdb-mode-hook', if you are using GDB; `dbx-mode-hook', if you are using DBX; `sdb-mode-hook', if you are using SDB; `xdb-mode-hook', if you are using XDB; `perldb-mode-hook', for Perl debugging mode. You can use these hooks to define custom key bindings for the debugger interaction buffer. *Note Hooks::. Here is a convenient way to define a command that sends a particular command string to the debugger, and set up a key binding for it in the debugger interaction buffer: (gud-def FUNCTION CMDSTRING BINDING DOCSTRING) This defines a command named FUNCTION which sends CMDSTRING to the debugger process, and gives it the documentation string DOCSTRING. You can use the command thus defined in any buffer. If BINDING is non-`nil', `gud-def' also binds the command to `C-c BINDING' in the GUD buffer's mode and to `C-x C-a BINDING' generally. The command string CMDSTRING may contain certain `%'-sequences that stand for data to be filled in at the time FUNCTION is called: `%f' The name of the current source file. If the current buffer is the GUD buffer, then the "current source file" is the file that the program stopped in. `%l' The number of the current source line. If the current buffer is the GUD buffer, then the "current source line" is the line that the program stopped in. `%e' The text of the C lvalue or function-call expression at or adjacent to point. `%a' The text of the hexadecimal address at or adjacent to point. `%p' The numeric argument of the called function, as a decimal number. If the command is used without a numeric argument, `%p' stands for the empty string. If you don't use `%p' in the command string, the command you define ignores any numeric argument. File: emacs, Node: Executing Lisp, Next: Lisp Libraries, Prev: Debuggers, Up: Building Executing Lisp Expressions ========================== Emacs has several different major modes for Lisp and Scheme. They are the same in terms of editing commands, but differ in the commands for executing Lisp expressions. Each mode has its own purpose. Emacs-Lisp mode The mode for editing source files of programs to run in Emacs Lisp. This mode defines `C-M-x' to evaluate the current defun. *Note Lisp Libraries::. Lisp Interaction mode The mode for an interactive session with Emacs Lisp. It defines LFD to evaluate the sexp before point and insert its value in the buffer. *Note Lisp Interaction::. Lisp mode The mode for editing source files of programs that run in Lisps other than Emacs Lisp. This mode defines `C-M-x' to send the current defun to an inferior Lisp process. *Note External Lisp::. Inferior Lisp mode The mode for an interactive session with an inferior Lisp process. This mode combines the special features of Lisp mode and Shell mode (*note Shell Mode::.). Scheme mode Like Lisp mode but for Scheme programs. Inferior Scheme mode The mode for an interactive session with an inferior Scheme process. * Menu: These subnodes of the chapter on editing programs describe the editing commands for working with Lisp programs, which are in fact available globally. * Lists:: Expressions with balanced parentheses. * List Commands:: The commands for working with list and sexps. * Defuns:: Each program is made up of separate functions. There are editing commands to operate on them. * Program Indent:: Adjusting indentation to show the nesting. * Matching:: Insertion of a close-delimiter flashes matching open. * Comments:: Inserting, killing, and aligning comments. File: emacs, Node: Lisp Libraries, Next: Lisp Interaction, Prev: Executing Lisp, Up: Building Libraries of Lisp Code for Emacs ================================ Lisp code for Emacs editing commands is stored in files whose names conventionally end in `.el'. This ending tells Emacs to edit them in Emacs-Lisp mode (*note Executing Lisp::.). To execute a file of Emacs Lisp code, use `M-x load-file'. This command reads a file name using the minibuffer and then executes the contents of that file as Lisp code. It is not necessary to visit the file first; in any case, this command reads the file as found on disk, not text in an Emacs buffer. Once a file of Lisp code is installed in the Emacs Lisp library directories, users can load it using `M-x load-library'. Programs can load it by calling `load-library', or with `load', a more primitive function that is similar but accepts some additional arguments. `M-x load-library' differs from `M-x load-file' in that it searches a sequence of directories and tries three file names in each directory. Suppose your argument is LIB; the three names are `LIB.elc', `LIB.el', and lastly just `LIB'. If `LIB.elc' exists, it is by convention the result of compiling `LIB.el'; it is better to load the compiled file, since it will load and run faster. If `load-library' finds that `LIB.el' is newer than `LIB.elc' file, it prints a warning, because it's likely that somebody made changes to the `.el' file and forgot to recompile it. Because the argument to `load-library' is usually not in itself a valid file name, file name completion is not available. Indeed, when using this command, you usually do not know exactly what file name will be used. The sequence of directories searched by `M-x load-library' is specified by the variable `load-path', a list of strings that are directory names. The default value of the list contains the directory where the Lisp code for Emacs itself is stored. If you have libraries of your own, put them in a single directory and add that directory to `load-path'. `nil' in this list stands for the current default directory, but it is probably not a good idea to put `nil' in the list. If you find yourself wishing that `nil' were in the list, most likely what you really want to do is use `M-x load-file' this once. Often you do not have to give any command to load a library, because the commands defined in the library are set up to "autoload" that library. Trying to run any of those commands calls `load' to load the library; this replaces the autoload definitions with the real ones from the library. Emacs Lisp code can be compiled into byte-code which loads faster, takes up less space when loaded, and executes faster. *Note Byte Compilation: (elisp)Byte Compilation. By convention, the compiled code for a library goes in a separate file whose name consists of the library source file with `c' appended. Thus, the compiled code for `foo.el' goes in `foo.elc'. That's why `load-library' searches for `.elc' files first. File: emacs, Node: Lisp Eval, Next: External Lisp, Prev: Lisp Interaction, Up: Building Evaluating Emacs-Lisp Expressions ================================= Lisp programs intended to be run in Emacs should be edited in Emacs-Lisp mode; this happens automatically for file names ending in `.el'. By contrast, Lisp mode itself is used for editing Lisp programs intended for other Lisp systems. To switch to Emacs-Lisp mode explicitly, use the command `M-x emacs-lisp-mode'. For testing of Lisp programs to run in Emacs, it is often useful to evaluate part of the program as it is found in the Emacs buffer. For example, after changing the text of a Lisp function definition, evaluating the definition installs the change for future calls to the function. Evaluation of Lisp expressions is also useful in any kind of editing, for invoking noninteractive functions (functions that are not commands). `M-:' Read a single Lisp expression in the minibuffer, evaluate it, and print the value in the echo area (`eval-expression'). `C-x C-e' Evaluate the Lisp expression before point, and print the value in the echo area (`eval-last-sexp'). `C-M-x' Evaluate the defun containing or after point, and print the value in the echo area (`eval-defun'). `M-x eval-region' Evaluate all the Lisp expressions in the region. `M-x eval-current-buffer' Evaluate all the Lisp expressions in the buffer. `M-:' (`eval-expression') is the most basic command for evaluating a Lisp expression interactively. It reads the expression using the minibuffer, so you can execute any expression on a buffer regardless of what the buffer contains. When the expression is evaluated, the current buffer is once again the buffer that was current when `M-:' was typed. `M-:' can easily confuse users who do not understand it. Therefore, `eval-expression' is normally a disabled command. Attempting to use this command asks for confirmation and gives you the option of enabling it; once you enable the command, confirmation will no longer be required for it. *Note Disabling::. In Emacs-Lisp mode, the key `C-M-x' is bound to the command `eval-defun', which parses the defun containing or following point as a Lisp expression and evaluates it. The value is printed in the echo area. This command is convenient for installing in the Lisp environment changes that you have just made in the text of a function definition. `C-M-x' treats `defvar' expressions specially. Normally, evaluating a `defvar' expression does nothing if the variable it defines already has a value. But `C-M-x' unconditionally resets the variable to the initial value specified in the `defvar' expression. This special feature is convenient for debugging Lisp programs. The command `C-x C-e' (`eval-last-sexp') evaluates the Lisp expression preceding point in the buffer, and displays the value in the echo area. It is available in all major modes, not just Emacs-Lisp mode. It does not treat `defvar' specially. If `C-M-x' or `C-x C-e' is given a numeric argument, it inserts the value into the current buffer at point, rather than displaying it in the echo area. The argument's value does not matter. The most general command for evaluating Lisp expressions from a buffer is `eval-region'. `M-x eval-region' parses the text of the region as one or more Lisp expressions, evaluating them one by one. `M-x eval-current-buffer' is similar but evaluates the entire buffer. This is a reasonable way to install the contents of a file of Lisp code that you are just ready to test. Later, as you find bugs and change individual functions, use `C-M-x' on each function that you change. This keeps the Lisp world in step with the source file. File: emacs, Node: Lisp Interaction, Next: Lisp Eval, Prev: Lisp Libraries, Up: Building Lisp Interaction Buffers ======================== The buffer `*scratch*' which is selected when Emacs starts up is provided for evaluating Lisp expressions interactively inside Emacs. The simplest way to use the `*scratch*' buffer is to insert Lisp expressions and type LFD after each expression. This command reads the Lisp expression before point, evaluates it, and inserts the value in printed representation before point. The result is a complete typescript of the expressions you have evaluated and their values. The `*scratch*' buffer's major mode is Lisp Interaction mode, which is the same as Emacs-Lisp mode except for the binding of LFD. The rationale for this feature is that Emacs must have a buffer when it starts up, but that buffer is not useful for editing files since a new buffer is made for every file that you visit. The Lisp interpreter typescript is the most useful thing I can think of for the initial buffer to do. Type `M-x lisp-interaction-mode' to put the current buffer in Lisp Interaction mode. File: emacs, Node: External Lisp, Prev: Lisp Eval, Up: Building Running an External Lisp ======================== Emacs has facilities for running programs in other Lisp systems. You can run a Lisp process as an inferior of Emacs, and pass expressions to it to be evaluated. You can also pass changed function definitions directly from the Emacs buffers in which you edit the Lisp programs to the inferior Lisp process. To run an inferior Lisp process, type `M-x run-lisp'. This runs the program named `lisp', the same program you would run by typing `lisp' as a shell command, with both input and output going through an Emacs buffer named `*lisp*'. That is to say, any "terminal output" from Lisp will go into the buffer, advancing point, and any "terminal input" for Lisp comes from text in the buffer. (You can change the name of the Lisp executable file by setting the variable `inferior-lisp-program'.) To give input to Lisp, go to the end of the buffer and type the input, terminated by RET. The `*lisp*' buffer is in Inferior Lisp mode, which combines the special characteristics of Lisp mode with most of the features of Shell mode (*note Shell Mode::.). The definition of RET to send a line to a subprocess is one of the features of Shell mode. For the source files of programs to run in external Lisps, use Lisp mode. This mode can be selected with `M-x lisp-mode', and is used automatically for files whose names end in `.l', `.lsp', or `.lisp', as most Lisp systems usually expect. When you edit a function in a Lisp program you are running, the easiest way to send the changed definition to the inferior Lisp process is the key `C-M-x'. In Lisp mode, this runs the function `lisp-eval-defun', which finds the defun around or following point and sends it as input to the Lisp process. (Emacs can send input to any inferior process regardless of what buffer is current.) Contrast the meanings of `C-M-x' in Lisp mode (for editing programs to be run in another Lisp system) and Emacs-Lisp mode (for editing Lisp programs to be run in Emacs): in both modes it has the effect of installing the function definition that point is in, but the way of doing so is different according to where the relevant Lisp environment is found. *Note Executing Lisp::. File: emacs, Node: Abbrevs, Next: Picture, Prev: Building, Up: Top Abbrevs ******* A defined "abbrev" is a word which "expands", if you insert it, into some different text. Abbrevs are defined by the user to expand in specific ways. For example, you might define `foo' as an abbrev expanding to `find outer otter'. Then you would be able to insert `find outer otter ' into the buffer by typing `f o o SPC'. A second kind of abbreviation facility is called "dynamic abbrev expansion". You use dynamic abbrev expansion with an explicit command to expand the letters in the buffer before point by looking for other words in the buffer that start with those letters. *Note Dynamic Abbrevs::. * Menu: * Abbrev Concepts:: Fundamentals of defined abbrevs. * Defining Abbrevs:: Defining an abbrev, so it will expand when typed. * Expanding Abbrevs:: Controlling expansion: prefixes, canceling expansion. * Editing Abbrevs:: Viewing or editing the entire list of defined abbrevs. * Saving Abbrevs:: Saving the entire list of abbrevs for another session. * Dynamic Abbrevs:: Abbreviations for words already in the buffer. File: emacs, Node: Abbrev Concepts, Next: Defining Abbrevs, Up: Abbrevs Abbrev Concepts =============== An "abbrev" is a word which has been defined to "expand" into a specified "expansion". When you insert a word-separator character following the abbrev, that expands the abbrev--replacing the abbrev with its expansion. For example, if `foo' is defined as an abbrev expanding to `find outer otter', then you can insert `find outer otter.' into the buffer by typing `f o o .'. Abbrevs expand only when Abbrev mode (a minor mode) is enabled. Disabling Abbrev mode does not cause abbrev definitions to be forgotten, but they do not expand until Abbrev mode is enabled again. The command `M-x abbrev-mode' toggles Abbrev mode; with a numeric argument, it turns Abbrev mode on if the argument is positive, off otherwise. *Note Minor Modes::. `abbrev-mode' is also a variable; Abbrev mode is on when the variable is non-`nil'. The variable `abbrev-mode' automatically becomes local to the current buffer when it is set. Abbrev definitions can be "mode-specific"--active only in one major mode. Abbrevs can also have "global" definitions that are active in all major modes. The same abbrev can have a global definition and various mode-specific definitions for different major modes. A mode specific definition for the current major mode overrides a global definition. Abbrevs can be defined interactively during the editing session. Lists of abbrev definitions can also be saved in files and reloaded in later sessions. Some users keep extensive lists of abbrevs that they load in every session. File: emacs, Node: Defining Abbrevs, Next: Expanding Abbrevs, Prev: Abbrev Concepts, Up: Abbrevs Defining Abbrevs ================ `C-x a g' Define an abbrev, using one or more words before point as its expansion (`add-global-abbrev'). `C-x a l' Similar, but define an abbrev specific to the current major mode (`add-mode-abbrev'). `C-x a i g' Define a word in the buffer as an abbrev (`inverse-add-global-abbrev'). `C-x a i l' Define a word in the buffer as a mode-specific abbrev (`inverse-add-mode-abbrev'). `M-x kill-all-abbrevs' This command discards all abbrev definitions currently in effect, leaving a blank slate. The usual way to define an abbrev is to enter the text you want the abbrev to expand to, position point after it, and type `C-x a g' (`add-global-abbrev'). This reads the abbrev itself using the minibuffer, and then defines it as an abbrev for one or more words before point. Use a numeric argument to say how many words before point should be taken as the expansion. For example, to define the abbrev `foo' as mentioned above, insert the text `find outer otter' and then type `C-u 3 C-x a g f o o RET'. An argument of zero to `C-x a g' means to use the contents of the region as the expansion of the abbrev being defined. The command `C-x a l' (`add-mode-abbrev') is similar, but defines a mode-specific abbrev. Mode specific abbrevs are active only in a particular major mode. `C-x a l' defines an abbrev for the major mode in effect at the time `C-x a l' is typed. The arguments work the same as for `C-x a g'. If the text already in the buffer is the abbrev, rather than its expansion, use command `C-x a i g' (`inverse-add-global-abbrev') instead of `C-x a g', or use `C-x a i l' (`inverse-add-mode-abbrev') instead of `C-x a l'. These commands are called "inverse" because they invert the meaning of the two text strings they use (one from the buffer and one read with the minibuffer). To change the definition of an abbrev, just define a new definition. When the abbrev has a prior definition, the abbrev definition commands ask for confirmation for replacing it. To remove an abbrev definition, give a negative argument to the abbrev definition command: `C-u - C-x a g' or `C-u - C-x a l'. The former removes a global definition, while the latter removes a mode-specific definition. `M-x kill-all-abbrevs' removes all the abbrev definitions there are, both global and local. File: emacs, Node: Expanding Abbrevs, Next: Editing Abbrevs, Prev: Defining Abbrevs, Up: Abbrevs Controlling Abbrev Expansion ============================ An abbrev expands whenever it is present in the buffer just before point and you type a self-inserting whitespace or punctuation character (SPC, comma, etc.). More precisely, any character that is not a word constituent expands an abbrev, and any word constituent character can be part of an abbrev. The most common way to use an abbrev is to insert it and then insert a punctuation character to expand it. Abbrev expansion preserves case; thus, `foo' expands into `find outer otter'; `Foo' into `Find outer otter', and `FOO' into `FIND OUTER OTTER' or `Find Outer Otter' according to the variable `abbrev-all-caps' (a non-`nil' value chooses the first of the two expansions). These commands are used to control abbrev expansion: `M-'' Separate a prefix from a following abbrev to be expanded (`abbrev-prefix-mark'). `C-x a e' Expand the abbrev before point (`expand-abbrev'). This is effective even when Abbrev mode is not enabled. `M-x expand-region-abbrevs' Expand some or all abbrevs found in the region. You may wish to expand an abbrev with a prefix attached; for example, if `cnst' expands into `construction', you might want to use it to enter `reconstruction'. It does not work to type `recnst', because that is not necessarily a defined abbrev. What you can do is use the command `M-'' (`abbrev-prefix-mark') in between the prefix `re' and the abbrev `cnst'. First, insert `re'. Then type `M-''; this inserts a hyphen in the buffer to indicate that it has done its work. Then insert the abbrev `cnst'; the buffer now contains `re-cnst'. Now insert a non-word character to expand the abbrev `cnst' into `construction'. This expansion step also deletes the hyphen that indicated `M-'' had been used. The result is the desired `reconstruction'. If you actually want the text of the abbrev in the buffer, rather than its expansion, you can accomplish this by inserting the following punctuation with `C-q'. Thus, `foo C-q ,' leaves `foo,' in the buffer. If you expand an abbrev by mistake, you can undo the expansion and bring back the abbrev itself by typing `C-_' to undo (*note Undo::.). This also undoes the insertion of the non-word character that expanded the abbrev. If the result you want is the terminating non-word character plus the unexpanded abbrev, you must reinsert the terminating character, quoting it with `C-q'. `M-x expand-region-abbrevs' searches through the region for defined abbrevs, and for each one found offers to replace it with its expansion. This command is useful if you have typed in text using abbrevs but forgot to turn on Abbrev mode first. It may also be useful together with a special set of abbrev definitions for making several global replacements at once. This command is effective even if Abbrev mode is not enabled. Expanding an abbrev runs the hook `pre-abbrev-expand-hook' (*note Hooks::.). File: emacs, Node: Editing Abbrevs, Next: Saving Abbrevs, Prev: Expanding Abbrevs, Up: Abbrevs Examining and Editing Abbrevs ============================= `M-x list-abbrevs' Display a list of all abbrev definitions. `M-x edit-abbrevs' Edit a list of abbrevs; you can add, alter or remove definitions. The output from `M-x list-abbrevs' looks like this: (lisp-mode-abbrev-table) "dk" 0 "define-key" (global-abbrev-table) "dfn" 0 "definition" (Some blank lines of no semantic significance, and some other abbrev tables, have been omitted.) A line containing a name in parentheses is the header for abbrevs in a particular abbrev table; `global-abbrev-table' contains all the global abbrevs, and the other abbrev tables that are named after major modes contain the mode-specific abbrevs. Within each abbrev table, each nonblank line defines one abbrev. The word at the beginning of the line is the abbrev. The number that follows is the number of times the abbrev has been expanded. Emacs keeps track of this to help you see which abbrevs you actually use, so that you can eliminate those that you don't use often. The string at the end of the line is the expansion. `M-x edit-abbrevs' allows you to add, change or kill abbrev definitions by editing a list of them in an Emacs buffer. The list has the same format described above. The buffer of abbrevs is called `*Abbrevs*', and is in Edit-Abbrevs mode. Type `C-c C-c' in this buffer to install the abbrev definitions as specified in the buffer--and delete any abbrev definitions not listed. The command `edit-abbrevs' is actually the same as `list-abbrevs' except that it selects the buffer `*Abbrevs*' whereas `list-abbrevs' merely displays it in another window. File: emacs, Node: Saving Abbrevs, Next: Dynamic Abbrevs, Prev: Editing Abbrevs, Up: Abbrevs Saving Abbrevs ============== These commands allow you to keep abbrev definitions between editing sessions. `M-x write-abbrev-file RET FILE RET' Write a file FILE describing all defined abbrevs. `M-x read-abbrev-file RET FILE RET' Read the file FILE and define abbrevs as specified therein. `M-x quietly-read-abbrev-file RET FILE RET' Similar but do not display a message about what is going on. `M-x define-abbrevs' Define abbrevs from definitions in current buffer. `M-x insert-abbrevs' Insert all abbrevs and their expansions into current buffer. `M-x write-abbrev-file' reads a file name using the minibuffer and then writes a description of all current abbrev definitions into that file. This is used to save abbrev definitions for use in a later session. The text stored in the file is a series of Lisp expressions that, when executed, define the same abbrevs that you currently have. `M-x read-abbrev-file' reads a file name using the minibuffer and then reads the file, defining abbrevs according to the contents of the file. `M-x quietly-read-abbrev-file' is the same except that it does not display a message in the echo area saying that it is doing its work; it is actually useful primarily in the `.emacs' file. If an empty argument is given to either of these functions, they use the file name specified in the variable `abbrev-file-name', which is by default `"~/.abbrev_defs"'. Emacs will offer to save abbrevs automatically if you have changed any of them, whenever it offers to save all files (for `C-x s' or `C-x C-c'). This feature can be inhibited by setting the variable `save-abbrevs' to `nil'. The commands `M-x insert-abbrevs' and `M-x define-abbrevs' are similar to the previous commands but work on text in an Emacs buffer. `M-x insert-abbrevs' inserts text into the current buffer before point, describing all current abbrev definitions; `M-x define-abbrevs' parses the entire current buffer and defines abbrevs accordingly. File: emacs, Node: Dynamic Abbrevs, Prev: Saving Abbrevs, Up: Abbrevs Dynamic Abbrev Expansion ======================== The abbrev facility described above operates automatically as you insert text, but all abbrevs must be defined explicitly. By contrast, "dynamic abbrevs" allow the meanings of abbrevs to be determined automatically from the contents of the buffer, but dynamic abbrev expansion happens only when you request it explicitly. `M-/' Expand the word in the buffer before point as a "dynamic abbrev", by searching in the buffer for words starting with that abbreviation (`dabbrev-expand'). `C-M-/' Complete the word before point as a dynamic abbrev (`dabbrev-completion'). For example, if the buffer contains `does this follow ' and you type `f o M-/', the effect is to insert `follow' because that is the last word in the buffer that starts with `fo'. A numeric argument to `M-/' says to take the second, third, etc. distinct expansion found looking backward from point. Repeating `M-/' searches for an alternative expansion by looking farther back. After considering the entire buffer before point, it searches the text after point. After searching all of the current buffer, `M-/' searches other buffers. A negative argument to `M-/', as in `C-u - M-/', says to search first for expansions after point, and second for expansions before point. If you repeat the `M-/' to look for another expansion, do not specify an argument. This tries all the expansions after point and then the expansions before point. After you have expanded a dynamic abbrev, you can copy additional words that follow the expansion in its original context. Simply type `SPC M-/' for each word you want to copy. The spacing and punctuation between words is copied along with the words. In shell scripts and makefiles, a variable name is sometimes prefixed with `$' and sometimes not. Major modes for this kind of text can customize dynamic abbreviation to handle optional prefixes by setting the variable `dabbrev-abbrev-skip-leading-regexp'. Its value should be a regular expression that matches the optional prefix that dynamic abbreviation should ignore. The command `C-M-/' (`dabbrev-completion') performs completion of a dynamic abbreviation. Instead of trying the possible expansions one by one, it finds all of them, then inserts the text that they have in common. If they have nothing in common, `C-M-/' displays a list of completions, from which you can select a choice in the usual manner. *Note Completion::. Dynamic abbrev expansion is completely independent of Abbrev mode; the expansion of a word with `M-/' is completely independent of whether it has a definition as an ordinary abbrev. File: emacs, Node: Picture, Next: Sending Mail, Prev: Abbrevs, Up: Top Editing Pictures **************** To edit a picture made out of text characters (for example, a picture of the division of a register into fields, as a comment in a program), use the command `M-x edit-picture' to enter Picture mode. In Picture mode, editing is based on the "quarter-plane" model of text, according to which the text characters lie studded on an area that stretches infinitely far to the right and downward. The concept of the end of a line does not exist in this model; the most you can say is where the last nonblank character on the line is found. Of course, Emacs really always considers text as a sequence of characters, and lines really do have ends. But Picture mode replaces the most frequently-used commands with variants that simulate the quarter-plane model of text. They do this by inserting spaces or by converting tabs to spaces. Most of the basic editing commands of Emacs are redefined by Picture mode to do essentially the same thing but in a quarter-plane way. In addition, Picture mode defines various keys starting with the `C-c' prefix to run special picture editing commands. One of these keys, `C-c C-c', is pretty important. Often a picture is part of a larger file that is usually edited in some other major mode. `M-x edit-picture' records the name of the previous major mode so you can use the `C-c C-c' command (`picture-mode-exit') later to go back to that mode. `C-c C-c' also deletes spaces from the ends of lines, unless given a numeric argument. The special commands of Picture mode all work in other modes (provided the `picture' library is loaded), but are not bound to keys except in Picture mode. The descriptions below talk of moving "one column" and so on, but all the picture mode commands handle numeric arguments as their normal equivalents do. Turning on Picture mode runs the hook `picture-mode-hook' (*note Hooks::.). * Menu: * Basic Picture:: Basic concepts and simple commands of Picture Mode. * Insert in Picture:: Controlling direction of cursor motion after "self-inserting" characters. * Tabs in Picture:: Various features for tab stops and indentation. * Rectangles in Picture:: Clearing and superimposing rectangles. File: emacs, Node: Basic Picture, Next: Insert in Picture, Prev: Picture, Up: Picture Basic Editing in Picture Mode ============================= Most keys do the same thing in Picture mode that they usually do, but do it in a quarter-plane style. For example, `C-f' is rebound to run `picture-forward-column', a command which moves point one column to the right, inserting a space if necessary so that the actual end of the line makes no difference. `C-b' is rebound to run `picture-backward-column', which always moves point left one column, converting a tab to multiple spaces if necessary. `C-n' and `C-p' are rebound to run `picture-move-down' and `picture-move-up', which can either insert spaces or convert tabs as necessary to make sure that point stays in exactly the same column. `C-e' runs `picture-end-of-line', which moves to after the last nonblank character on the line. There is no need to change `C-a', as the choice of screen model does not affect beginnings of lines. Insertion of text is adapted to the quarter-plane screen model through the use of Overwrite mode (*note Minor Modes::.). Self-inserting characters replace existing text, column by column, rather than pushing existing text to the right. RET runs `picture-newline', which just moves to the beginning of the following line so that new text will replace that line. Picture mode provides erasure instead of deletion and killing of text. DEL (`picture-backward-clear-column') replaces the preceding character with a space rather than removing it; this moves point backwards. `C-d' (`picture-clear-column') replaces the next character or characters with spaces, but does not move point. (If you want to clear characters to spaces and move forward over them, use SPC.) `C-k' (`picture-clear-line') really kills the contents of lines, but does not delete the newlines from the buffer. To do actual insertion, you must use special commands. `C-o' (`picture-open-line') creates a blank line after the current line; it never splits a line. `C-M-o', `split-line', makes sense in Picture mode, so it is not changed. LFD (`picture-duplicate-line') inserts below the current line another line with the same contents. To do actual deletion in Picture mode, use `C-w', `C-c C-d' (which is defined as `delete-char', as `C-d' is in other modes), or one of the picture rectangle commands (*note Rectangles in Picture::.). File: emacs, Node: Insert in Picture, Next: Tabs in Picture, Prev: Basic Picture, Up: Picture Controlling Motion after Insert =============================== Since "self-inserting" characters in Picture mode overwrite and move point, there is no essential restriction on how point should be moved. Normally point moves right, but you can specify any of the eight orthogonal or diagonal directions for motion after a "self-inserting" character. This is useful for drawing lines in the buffer. `C-c <' Move left after insertion (`picture-movement-left'). `C-c >' Move right after insertion (`picture-movement-right'). `C-c ^' Move up after insertion (`picture-movement-up'). `C-c .' Move down after insertion (`picture-movement-down'). `C-c `' Move up and left ("northwest") after insertion (`picture-movement-nw'). `C-c '' Move up and right ("northeast") after insertion (`picture-movement-ne'). `C-c /' Move down and left ("southwest") after insertion (`picture-movement-sw'). `C-c \' Move down and right ("southeast") after insertion (`picture-movement-se'). Two motion commands move based on the current Picture insertion direction. The command `C-c C-f' (`picture-motion') moves in the same direction as motion after "insertion" currently does, while `C-c C-b' (`picture-motion-reverse') moves in the opposite direction. File: emacs, Node: Tabs in Picture, Next: Rectangles in Picture, Prev: Insert in Picture, Up: Picture Picture Mode Tabs ================= Two kinds of tab-like action are provided in Picture mode. Use `M-TAB' (`picture-tab-search') for context-based tabbing. With no argument, it moves to a point underneath the next "interesting" character that follows whitespace in the previous nonblank line. "Next" here means "appearing at a horizontal position greater than the one point starts out at." With an argument, as in `C-u M-TAB', this command moves to the next such interesting character in the current line. `M-TAB' does not change the text; it only moves point. "Interesting" characters are defined by the variable `picture-tab-chars', which should define a set of characters. The syntax for this variable is like the syntax used inside of `[...]' in a regular expression--but without the `[' and the `]'. Its default value is `"!-~"'. TAB itself runs `picture-tab', which operates based on the current tab stop settings; it is the Picture mode equivalent of `tab-to-tab-stop'. Normally it just moves point, but with a numeric argument it clears the text that it moves over. The context-based and tab-stop-based forms of tabbing are brought together by the command `C-c TAB', `picture-set-tab-stops'. This command sets the tab stops to the positions which `M-TAB' would consider significant in the current line. The use of this command, together with TAB, can get the effect of context-based tabbing. But `M-TAB' is more convenient in the cases where it is sufficient. File: emacs, Node: Rectangles in Picture, Prev: Tabs in Picture, Up: Picture Picture Mode Rectangle Commands =============================== Picture mode defines commands for working on rectangular pieces of the text in ways that fit with the quarter-plane model. The standard rectangle commands may also be useful (*note Rectangles::.). `C-c C-k' Clear out the region-rectangle with spaces (`picture-clear-rectangle'). With argument, delete the text. `C-c C-w R' Similar but save rectangle contents in register R first (`picture-clear-rectangle-to-register'). `C-c C-y' Copy last killed rectangle into the buffer by overwriting, with upper left corner at point (`picture-yank-rectangle'). With argument, insert instead. `C-c C-x R' Similar, but use the rectangle in register R (`picture-yank-rectangle-from-register'). The picture rectangle commands `C-c C-k' (`picture-clear-rectangle') and `C-c C-w' (`picture-clear-rectangle-to-register') differ from the standard rectangle commands in that they normally clear the rectangle instead of deleting it; this is analogous with the way `C-d' is changed in Picture mode. However, deletion of rectangles can be useful in Picture mode, so these commands delete the rectangle if given a numeric argument. `C-c C-k' either with or without a numeric argument saves the rectangle for `C-c C-y'. The Picture mode commands for yanking rectangles differ from the standard ones in overwriting instead of inserting. This is the same way that Picture mode insertion of other text differs from other modes. `C-c C-y' (`picture-yank-rectangle') inserts (by overwriting) the rectangle that was most recently killed, while `C-c C-x' (`picture-yank-rectangle-from-register') does likewise for the rectangle found in a specified register. File: emacs, Node: Sending Mail, Next: Rmail, Prev: Picture, Up: Top Sending Mail ************ To send a message in Emacs, you start by typing a command (`C-x m') to select and initialize the `*mail*' buffer. Then you edit the text and headers of the message in this buffer, and type another command (`C-c C-s' or `C-c C-c') to send the message. `C-x m' Begin composing a message to send (`mail'). `C-x 4 m' Likewise, but display the message in another window (`mail-other-window'). `C-x 5 m' Likewise, but make a new frame (`mail-other-frame'). `C-c C-s' In Mail mode, send the message (`mail-send'). `C-c C-c' Send the message and bury the mail buffer (`mail-send-and-exit'). The command `C-x m' (`mail') selects a buffer named `*mail*' and initializes it with the skeleton of an outgoing message. `C-x 4 m' (`mail-other-window') selects the `*mail*' buffer in a different window, leaving the previous current buffer visible. `C-x 5 m' (`mail-other-frame') creates a new frame to select the `*mail*' buffer. Because the mail composition buffer is an ordinary Emacs buffer, you can switch to other buffers while in the middle of composing mail, and switch back later (or never). If you use the `C-x m' command again when you have been composing another message but have not sent it, you are asked to confirm before the old message is erased. If you answer `n', the `*mail*' buffer is left selected with its old contents, so you can finish the old message and send it. `C-u C-x m' is another way to do this. Sending the message marks the `*mail*' buffer "unmodified", which avoids the need for confirmation when `C-x m' is next used. If you are composing a message in the `*mail*' buffer and want to send another message before finishing the first, rename the `*mail*' buffer using `M-x rename-uniquely' (*note Misc Buffer::.). Then you can use `C-x m' or its variants described above to make a new `*mail*' buffer. Once you've done that, you can work with each mail buffer independently. * Menu: * Format: Mail Format. Format of the mail being composed. * Headers: Mail Headers. Details of permitted mail header fields. * Aliases: Mail Aliases. Abbreviating and grouping mail addresses. * Mode: Mail Mode. Special commands for editing mail being composed. * Spook: Distracting NSA. How to distract the NSA's attention. File: emacs, Node: Mail Format, Next: Mail Headers, Up: Sending Mail The Format of the Mail Buffer ============================= In addition to the "text" or "body", a message has "header fields" which say who sent it, when, to whom, why, and so on. Some header fields such as the date and sender are created automatically after the message is sent. Others, such as the recipient names, must be specified by you in order to send the message properly. Mail mode provides a few commands to help you edit some header fields, and some are preinitialized in the buffer automatically at times. You can insert and edit header fields using ordinary editing commands. The line in the buffer that says --text follows this line-- is a special delimiter that separates the headers you have specified from the text. Whatever follows this line is the text of the message; the headers precede it. The delimiter line itself does not appear in the message actually sent. The text used for the delimiter line is controlled by the variable `mail-header-separator'. Here is an example of what the headers and text in the mail buffer might look like. To: gnu@prep.ai.mit.edu CC: lungfish@spam.org, byob@spam.org Subject: The Emacs Manual --Text follows this line-- Please ignore this message.