This is ../info/emacs, produced by makeinfo version 4.0 from emacs.texi.

   This is the thirteenth edition of the `GNU Emacs Manual', updated
for Emacs version 20.7.

INFO-DIR-SECTION Editors
START-INFO-DIR-ENTRY
* Emacs: (emacs).	The extensible self-documenting text editor.
END-INFO-DIR-ENTRY

   Published by the Free Software Foundation 59 Temple Place, Suite 330
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   Copyright (C) 1985, 1986, 1987, 1993, 1994, 1995, 1996, 1997, 1998,
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File: emacs,  Node: Debuggers,  Next: Executing Lisp,  Prev: Compilation Shell,  Up: Building

Running Debuggers Under Emacs
=============================

   The GUD (Grand Unified Debugger) library provides an interface to
various symbolic debuggers from within Emacs.  We recommend the debugger
GDB, which is free software, but you can also run DBX, SDB or XDB if you
have them.  GUD can also serve as an interface to the Perl's debugging
mode, the Python debugger PDB, and to JDB, the Java Debugger.

* Menu:

* Starting GUD::	How to start a debugger subprocess.
* Debugger Operation::	Connection between the debugger and source buffers.
* Commands of GUD::	Key bindings for common commands.
* GUD Customization::	Defining your own commands for GUD.


File: emacs,  Node: Starting GUD,  Next: Debugger Operation,  Up: Debuggers

Starting GUD
------------

   There are several commands for starting a debugger, each
corresponding to a particular debugger program.

`M-x gdb <RET> FILE <RET>'
     Run GDB as a subprocess of Emacs.  This command creates a buffer
     for input and output to GDB, and switches to it.  If a GDB buffer
     already exists, it just switches to that buffer.

`M-x dbx <RET> FILE <RET>'
     Similar, but run DBX instead of GDB.

`M-x xdb <RET> FILE <RET>'
     Similar, but run XDB instead of GDB.  Use the variable
     `gud-xdb-directories' to specify directories to search for source
     files.

`M-x sdb <RET> FILE <RET>'
     Similar, but run SDB instead of GDB.

     Some versions of SDB do not mention source file names in their
     messages.  When you use them, you need to have a valid tags table
     (*note Tags::) in order for GUD to find functions in the source
     code.  If you have not visited a tags table or the tags table
     doesn't list one of the functions, you get a message saying `The
     sdb support requires a valid tags table to work'.  If this
     happens, generate a valid tags table in the working directory and
     try again.

`M-x perldb <RET> FILE <RET>'
     Run the Perl interpreter in debug mode to debug FILE, a Perl
     program.

`M-x jdb <RET> FILE <RET>'
     Run the Java debugger to debug FILE.

`M-x pdb <RET> FILE <RET>'
     Run the Python debugger to debug FILE.

   Each of these commands takes one argument: a command line to invoke
the debugger.  In the simplest case, specify just the name of the
executable file you want to debug.  You may also use options that the
debugger supports.  However, shell wildcards and variables are not
allowed.  GUD assumes that the first argument not starting with a `-'
is the executable file name.

   Emacs can only run one debugger process at a time.


File: emacs,  Node: Debugger Operation,  Next: Commands of GUD,  Prev: Starting GUD,  Up: Debuggers

Debugger Operation
------------------

   When you run a debugger with GUD, the debugger uses an Emacs buffer
for its ordinary input and output.  This is called the GUD buffer.  The
debugger displays the source files of the program by visiting them in
Emacs buffers.  An arrow (`=>') in one of these buffers indicates the
current execution line.  Moving point in this buffer does not move the
arrow.

   You can start editing these source files at any time in the buffers
that were made to display them.  The arrow is not part of the file's
text; it appears only on the screen.  If you do modify a source file,
keep in mind that inserting or deleting lines will throw off the arrow's
positioning; GUD has no way of figuring out which line corresponded
before your changes to the line number in a debugger message.  Also,
you'll typically have to recompile and restart the program for your
changes to be reflected in the debugger's tables.

   If you wish, you can control your debugger process entirely through
the debugger buffer, which uses a variant of Shell mode.  All the usual
commands for your debugger are available, and you can use the Shell mode
history commands to repeat them.  *Note Shell Mode::.


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 key bindings that start with `C-x C-a' are available in the GUD
interaction 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.

   Because <TAB> serves as a completion command, you can't use it to
enter a tab as input to the program you are debugging with GDB.
Instead, type `C-q <TAB>' to enter a tab.


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;
`jdb-mode-hook', for PDB; `jdb-mode-hook', for JDB.  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
     `C-j' 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.

   Most editing commands for working with Lisp programs are in fact
available globally.  *Note Programs::.


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.

   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', `C-x C-e', or `M-:' 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 `C-j' 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 `C-j'.

   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.

   An alternative way of evaluating Emacs Lisp expressions interactively
is to use Inferior Emacs-Lisp mode, which provides an interface rather
like Shell mode (*note Shell Mode::) for evaluating Emacs Lisp
expressions.  Type `M-x ielm' to create an `*ielm*' buffer which uses
this 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.
* Dabbrev Customization:: What is a word, for dynamic abbrevs.  Case handling.


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'.  You can also use the command `M-x
unexpand-abbrev' to cancel the last expansion without deleting the
terminating character.

   `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,  Next: Dabbrev Customization,  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 scanning all the text before
point, it searches the text after point.  The variable `dabbrev-limit',
if non-`nil', specifies how far in the buffer to search for an
expansion.

   After scanning the current buffer, `M-/' normally searches other
buffers, unless you have set `dabbrev-check-all-buffers' to `nil'.

   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.

   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: Dabbrev Customization,  Prev: Dynamic Abbrevs,  Up: Abbrevs

Customizing Dynamic Abbreviation
================================

   Normally, dynamic abbrev expansion ignores case when searching for
expansions.  That is, the expansion need not agree in case with the word
you are expanding.

   This feature is controlled by the variable
`dabbrev-case-fold-search'.  If it is `t', case is ignored in this
search; if `nil', the word and the expansion must match in case.  If
the value of `dabbrev-case-fold-search' is `case-fold-search', which is
true by default, then the variable `case-fold-search' controls whether
to ignore case while searching for expansions.

   Normally, dynamic abbrev expansion preserves the case pattern _of
the abbrev you have typed_, by converting the expansion to that case
pattern.

   The variable `dabbrev-case-replace' controls whether to preserve the
case pattern of the abbrev.  If it is `t', the abbrev's case pattern is
preserved in most cases; if `nil', the expansion is always copied
verbatim.  If the value of `dabbrev-case-replace' is `case-replace',
which is true by default, then the variable `case-replace' controls
whether to copy the expansion verbatim.

   However, if the expansion contains a complex mixed case pattern, and
the abbrev matches this pattern as far as it goes, then the expansion is
always copied verbatim, regardless of those variables.  Thus, for
example, if the buffer contains `variableWithSillyCasePattern', and you
type `v a M-/', it copies the expansion verbatim including its case
pattern.

   The variable `dabbrev-abbrev-char-regexp', if non-`nil', controls
which characters are considered part of a word, for dynamic expansion
purposes.  The regular expression must match just one character, never
two or more.  The same regular expression also determines which
characters are part of an expansion.  The value `nil' has a special
meaning: abbreviations are made of word characters, but expansions are
made of word and symbol characters.

   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.


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.  `C-j' (`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.

   It may be convenient to prevent use of actual tab characters in
pictures.  For example, this prevents `C-x <TAB>' from messing up the
picture.  You can do this by setting the variable `indent-tabs-mode' to
`nil'.  *Note Just Spaces::.


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.

