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Info file emacs, produced by texinfo-format-buffer -*-Text-*-
from file emacs.tex

This file documents the GNU Emacs editor.

Permission is granted to make and distribute verbatim copies of
this manual provided the copyright notice and this permission notice
are preserved on all copies.

Permission is granted to copy and distribute modified versions of this
manual under the conditions for verbatim copying, provided also that the
sections entitled "The GNU Manifesto", "Distribution" and "GNU Emacs
General Public License" are included exactly as in the original, and
provided that the entire resulting derived work is distributed under the
terms of a permission notice identical to this one.

Permission is granted to copy and distribute translations of this manual
into another language, under the above conditions for modified versions,
except that the sections entitled "The GNU Manifesto", "Distribution"
and "GNU Emacs General Public License" may be included in a translation
approved by the author instead of in the original English.

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File: emacs Node: Fortran Columns, Prev: Fortran Comments, Up: Fortran, Next: Fortran Abbrev

Columns
-------

`C-c C-r'
Displays a "column ruler" momentarily above the current line
(`fortran-column-ruler').
`C-c C-w'
Splits the current window horizontally so that it is 72 columns wide.
This may help you avoid going over that limit (`fortran-window-create').

The command `C-c C-r' (`fortran-column-ruler') shows a column
ruler momentarily above the current line. The comment ruler is two lines
of text that show you the locations of columns with special significance
in Fortran programs. Square brackets show the limits of the columns for
line numbers, and curly brackets show the limits of the columns for the
statement body. Column numbers appear above them.

Note that the column numbers count from zero, as always in GNU Emacs. As
a result, the numbers may not be those you are familiar with; but the
actual positions in the line are standard Fortran.

The text used to display the column ruler is the value of the variable
`fortran-comment-ruler'. By changing this variable, you can change
the display.

For even more help, use `C-c C-w' (`fortran-create-window'), a
command which splits the current window horizontally, making a window 72
columns wide. By editing in this window you can immediately see when you
make a line too wide to be correct Fortran.

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File: emacs Node: Fortran Abbrev, Prev: Fortran Columns, Up: Fortran

Fortran Keyword Abbrevs
-----------------------

Fortran mode provides many built-in abbrevs for common keywords and
declarations. These are the same sort of abbrev that you can define
yourself, and they expand just like other abbrevs if you turn on Abbrev
mode. *Note Abbrevs::.

The build-in abbrevs are unusual in one way: they all start with a
semicolon, You cannot normally use semicolon in an abbrev, but Fortran mode
makes this possible by changing the syntax of semicolon to "word
constituent".

For example, one built-in Fortran abbrev is `;c' for `continue'. If you
insert `;c' and then insert a punctuation character such as a space or a
newline, the `;c' will change automatically to `continue', provided Abbrev
mode is enabled.

Type `;?' or `;C-h' to display a list of all the built-in
Fortran abbrevs and what they stand for.

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File: emacs Node: Running, Prev: Programs, Up: Top, Next: Abbrevs

Compiling and Testing Programs
******************************

The previous chapter discusses the Emacs commands that are useful for
making changes in programs. This chapter deals with commands that assist
in the larger process of developing and maintaining programs.

* Menu:

* Compilation:: Compiling programs in languages other than Lisp
(C, Pascal, etc.)
* Modes: Lisp Modes. Various modes for editing Lisp programs, with
different facilities for running the Lisp programs.
* Libraries: Lisp Libraries. Creating Lisp programs to run in Emacs.
* Interaction: Lisp Interaction. Executing Lisp in an Emacs buffer.
* Eval: Lisp Eval. Executing a single Lisp expression in Emacs.
* Debug: Lisp Debug. Debugging Lisp programs running in Emacs.
* External Lisp:: Communicating through Emacs with a separate Lisp.

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File: emacs Node: Compilation, Prev: Running, Up: Running, Next: Lisp Modes

Running `make', or Compilers Generally
======================================

Emacs can run compilers for noninteractive languages such as C and
Fortran as inferior processes, feeding the error log into an Emacs buffer.
It can also parse the error messages and visit the files in which errors
are found, moving point right to the line where the error occurred.

`M-x compile'
Run a compiler asynchronously under Emacs, with error messages to
`*compilation*' buffer.
`M-x grep'
Run `grep' asynchronously under Emacs, with matching lines
listed in the `*compilation*' buffer.
`M-x kill-compiler'
`M-x kill-grep'
Kill the running compilation or `grep' subprocess.
`C-x `'
Visit the locus of the next compiler error message or `grep' match.

To run `make' or another compiler, do `M-x compile'. This command
reads a shell command line using the minibuffer, and then executes the
specified command line in an inferior shell with output going to the buffer
named `*compilation*'. The current buffer's default directory is used
as the working directory for the execution of the command; normally,
therefore, the makefile comes from this directory.

When the shell command line is read, the minibuffer appears containing a
default command line, which is the command you used the last time you did
`M-x compile'. If you type just RET, the same command line is used
again. The first `M-x compile' provides `make -k' as the default.
The default is taken from the variable `compile-command'; if the
appropriate compilation command for a file is something other than
`make -k', it can be useful to have the file specify a local value for
`compile-command' (*Note File Variables::).

Starting a compilation causes the buffer `*compilation*' to be
displayed in another window but not selected. Its mode line tells you
whether compilation is finished, with the word `run' or `exit' inside
the parentheses. You do not have to keep this buffer visible; compilation
continues in any case.

To kill the compilation process, do `M-x kill-compilation'. You will see
that the mode line of the `*compilation*' buffer changes to say `signal'
instead of `run'. Starting a new compilation also kills any running
compilation, as only one can exist at any time. However, this requires
confirmation before actually killing a compilation that is running.

To parse the compiler error messages, type `C-x `' (`next-error'). The
character following the `C-x' is the grave accent, not the single
quote. This command displays the buffer `*compilation*' in one window
and the buffer in which the next error occurred in another window. Point
in that buffer is moved to the line where the error was found. The
corresponding error message is scrolled to the top of the window in which
`*compilation*' is displayed.

The first time `C-x `' is used after the start of a compilation, it
parses all the error messages, visits all the files that have error
messages, and makes markers pointing at the lines that the error messages
refer to. Then it moves to the first error message location. Subsequent
uses of `C-x `' advance down the data set up by the first use. When
the preparsed error messages are exhausted, the next `C-x `' checks for
any more error messages that have come in; this is useful if you start
editing the compiler errors while the compilation is still going on. If no
more error messages have come in, `C-x `' reports an error.

`C-u C-x `' discards the preparsed error message data and parses the
`*compilation*' buffer over again, then displaying the first error.
This way, you can process the same set of errors again.

Instead of running a compiler, you can run `grep' and see the lines
on which matches were found. To do this, type `M-x grep' with an argument
line that contains the same arguments you would give `grep' when running
it normally: a `grep'-style regexp (usually in singlequotes to quote
the shell's special characters) followed by filenames which may use wildcards.
The output from `grep' goes in the `*compilation*' buffer and the
lines that matched can be found with `C-x `' as if they were compilation
errors.

Note: a shell is used to run the compile command, but the shell is told
that it should be noninteractive. This means in particular that the shell
starts up with no prompt. If you find your usual shell prompt making an
unsightly appearance in the `*compilation*' buffer, it means you have
made a mistake in your shell's init file (`.cshrc' or `.shrc' or
...) by setting the prompt unconditionally. The shell init file should
set the prompt only if there already is a prompt. In `csh', here is
how to do it:

if ($?prompt) set prompt = ...

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File: emacs Node: Lisp Modes, Prev: Compilation, Up: Running, Next: Lisp Libraries

Major Modes for Lisp
====================

Emacs has four different major modes for Lisp. They are the same in
terms of editing commands, but differ in the commands for executing Lisp
expressions.

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.

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File: emacs Node: Lisp Libraries, Prev: Lisp Modes, Up: Running, Next: Lisp Eval

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 Lisp Modes::).

* Menu:

* Loading:: Loading libraries of Lisp code into Emacs for use.
* Compiling Libraries:: Compiling a library makes it load and run faster.
* Mocklisp:: Converting Mocklisp to Lisp so GNU Emacs can run it.

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File: emacs Node: Loading, Prev: Lisp Libraries, Up: Lisp Libraries, Next: Compiling Libraries

Loading Libraries
-----------------

To execute a file of Emacs Lisp, 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. The three names are, first, the specified name with `.elc'
appended; second, with `.el' appended; third, the specified
name alone. A `.elc' file would be the result of compiling the Lisp
file into byte code; it is loaded if possible in preference to the Lisp
file itself because the compiled file will load and run faster.

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.
Running any of those commands causes `load' to be called to load the
library; this replaces the autoload definitions with the real ones from the
library.

If autoloading a file does not finish, either because of an error or
because of a `C-g' quit, all function definitions made by the file are
undone automatically. So are any calls to `provide'. As a consequence,
if you use one of the autoloadable commands again, the entire file will be
loaded a second time. This prevents problems where the command is no
longer autoloading but it works wrong because not all the file was loaded.
Function definitions are undone only for autoloading; explicit calls to
`load' do not undo anything if loading is not completed.

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File: emacs Node: Compiling Libraries, Prev: Loading, Up: Lisp Libraries, Next: Mocklisp

Compiling Libraries
-------------------

Emacs Lisp code can be compiled into byte-code which loads faster,
takes up less space when loaded, and executes faster.

The way to make a byte-code compiled file from an Emacs-Lisp source file
is with `M-x byte-compile-file'. The default argument for this
function is the file visited in the current buffer. It reads the specified
file, compiles it into byte code, and writes an output file whose name is
made by appending `c' to the input file name. Thus, the file
`rmail.el' would be compiled into `rmail.elc'.

To recompile the changed Lisp files in a directory, use `M-x
byte-recompile-directory'. Specify just the directory name as an argument.
Each `.el' file that has been byte-compiled before is byte-compiled
again if it has changed since the previous compilation. A numeric argument
to this command tells it to offer to compile each `.el' file that has
not already been compiled. You must answer `y' or `n' to each
offer.

Emacs can be invoked noninteractively from the shell to do byte compilation
with the aid of the function `batch-byte-compile'. In this case,
the files to be compiled are specified with command-line arguments.
Use a shell command of the form

emacs -batch -f batch-byte-compile FILES...

Directory names may also be given as arguments;
`byte-recompile-directory' is invoked (in effect) on each such directory.
`batch-byte-compile' uses all the remaining command-line arguments as
file or directory names, then kills the Emacs process.

`M-x disassemble' explains the result of byte compilation. Its
argument is a function name. It displays the byte-compiled code in a help
window in symbolic form, one instruction per line. If the instruction
refers to a variable or constant, that is shown too.

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File: emacs Node: Mocklisp, Prev: Compiling Libraries, Up: Lisp Libraries

Converting Mocklisp to Lisp
---------------------------

GNU Emacs can run Mocklisp files by converting them to Emacs Lisp first.
To convert a Mocklisp file, visit it and then type `M-x
convert-mocklisp-buffer'. Then save the resulting buffer of Lisp file in a
file whose name ends in `.el' and use the new file as a Lisp library.

It does not currently work to byte-compile converted Mocklisp code.
This is because converted Mocklisp code uses some special Lisp features
to deal with Mocklisp's incompatible ideas of how arguments are evaluated
and which values signify "true" or "false".

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File: emacs Node: Lisp Eval, Prev: Lisp Libraries, Up: Running, Next: Lisp Debug

Evaluating Emacs-Lisp Expressions
=================================

Lisp programs intended to be run in Emacs should be edited in Emacs-Lisp
mode; this will happen automatically for file names ending in `.el'.
By contrast, Lisp mode itself is used for editing Lisp programs intended
for other Lisp systems. Emacs-Lisp mode can be selected with the command
`M-x emacs-lisp-mode'.

For testing of Lisp programs to run in Emacs, it is useful to be able 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 task
for invoking noninteractive functions (functions that are not commands).

`M-ESC'
Read a Lisp expression in the minibuffer, evaluate it, and print the
value in the minibuffer (`eval-expression').
`C-x C-e'
Evaluate the Lisp expression before point, and print the value in the
minibuffer (`eval-last-sexp').
`C-M-x'
Evaluate the defun containing or after point, and print the value in
the minibuffer (`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-ESC' (`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-ESC' was
typed.

`M-ESC' can easily confuse users who do not understand it, especially on
keyboards with autorepeat where it can result from holding down the ESC key
for too long. 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 function `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.

The command `C-x C-e' (`eval-last-sexp') performs a similar job
but is available in all major modes, not just Emacs-Lisp mode. It finds
the sexp before point, reads it as a Lisp expression, evaluates it, and
prints the value in the echo area. It is sometimes useful to type in an
expression and then, with point still after it, type `C-x C-e'.

If `C-M-x' or `C-x C-e' is given a numeric argument, it prints the value
by insertion into the current buffer at point, rather than in the echo
area. The argument 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. After finding and fixing a bug, use `C-M-x' on each function
that you change, to keep the Lisp world in step with the source file.

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File: emacs Node: Lisp Debug, Prev: Lisp Eval, Up: Running, Next: Lisp Interaction

The Emacs-Lisp Debugger
=======================

GNU Emacs contains a debugger for Lisp programs executing inside it.
This debugger is normally not used; many commands frequently get Lisp
errors when invoked in inappropriate contexts (such as `C-f' at the end of
the buffer) and it would be very unpleasant for that to enter a special
debugging mode. When you want to make Lisp errors invoke the debugger, you
must set the variable `debug-on-error' to non-`nil'. Quitting with `C-g'
is not considered an error, and `debug-on-error' has no effect on the
handling of `C-g'. However, if you set `debug-on-quit' non-`nil', `C-g'
will invoke the debugger. This can be useful for debugging an infinite
loop; type `C-g' once the loop has had time to reach its steady state.
`debug-on-quit' has no effect on errors.

You can also cause the debugger to be entered when a specified function
is called, or at a particular place in Lisp code. Use `M-x debug-on-entry'
with argument FUN-NAME to cause function FUN-NAME to enter the debugger as
soon as it is called. Use `M-x cancel-debug-on-entry' to make the function
stop entering the debugger when called. (Redefining the function also does
this.) To enter the debugger from some other place in Lisp code, you must
insert the expression `(debug)' there and install the changed code with
`C-M-x'. *Note Lisp Eval::.

When the debugger is entered, it displays the previously selected buffer
in one window and a buffer named `*Backtrace*' in another window. The
backtrace buffer contains one line for each level of Lisp function
execution currently going on. At the beginning of this buffer is a message
describing the reason that the debugger was invoked (such as, what error
message if it was invoked due to an error).

The backtrace buffer is read-only, and is in a special major mode,
Backtrace mode, in which letters are defined as debugger commands. The
usual Emacs editing commands are available; you can switch windows to
examine the buffer that was being edited at the time of the error, and you
can also switch buffers, visit files, and do any other sort of editing.
However, the debugger is a recursive editing level (*Note Recursive Edit::)
and it is wise to go back to the backtrace buffer and exit the debugger
officially when you don't want to use it any more. Exiting the debugger
kills the backtrace buffer.

The contents of the backtrace buffer show you the functions that are
executing and the arguments that were given to them. It has the additional
purpose of allowing you to specify a stack frame by moving point to the line
describing that frame. The frame whose line point is on is considered the
"current frame". Some of the debugger commands operate on the current
frame. Debugger commands are mainly used for stepping through code an
expression at a time. Here is a list of them.

`c'
Exit the debugger and continue execution. In most cases, execution of
the program continues as if the debugger had never been entered (aside
from the effect of any variables or data structures you may have
changed while inside the debugger). This includes entry to the
debugger due to function entry or exit, explicit invocation, quitting
or certain errors. Most errors cannot be continued; trying to
continue one of them causes the same error to occur again.
`d'
Continue execution, but enter the debugger the next time a Lisp
function is called. This allows you to step through the
subexpressions of an expression, seeing what values the subexpressions
compute and what else they do.

The stack frame made for the function call which enters the debugger
in this way will be flagged automatically for the debugger to be called
when the frame is exited. You can use the `u' command to cancel
this flag.
`b'
Set up to enter the debugger when the current frame is exited. Frames
that will invoke the debugger on exit are flagged with stars.
`u'
Don't enter the debugger when the current frame is exited. This
cancels a `b' command on that frame.
`e'
Read a Lisp expression in the minibuffer, evaluate it, and print the
value in the echo area. This is the same as the command `M-ESC',
except that `e' is not normally disabled like `M-ESC'.
`q'
Terminate the program being debugged; return to top-level Emacs
command execution.

If the debugger was entered due to a `C-g' but you really want
to quit, not to debug, use the `q' command.
`r'
Return a value from the debugger. The value is computed by reading an
expression with the minibuffer and evaluating it.

The value returned by the debugger makes a difference when the debugger
was invoked due to exit from a Lisp call frame (as requested with `b');
then the value specified in the `r' command is used as the value of
that frame.

The debugger's return value also matters with many errors. For example,
`wrong-type-argument' errors will use the debugger's return value
instead of the invalid argument; `no-catch' errors will use the
debugger value as a throw tag instead of the tag that was not found.
If an error was signaled by calling the Lisp function `signal',
the debugger's return value is returned as the value of `signal'.

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File: emacs Node: Lisp Interaction, Prev: Lisp Debug, Up: Running, Next: External Lisp

Lisp Interaction Buffers
========================

The buffer `*scratch*' which is selected when Emacs starts up is
provided for evaluating Lisp expressions interactively inside Emacs. Both
the expressions you evaluate and their output goes in the buffer.

The `*scratch*' buffer's major mode is Lisp Interaction mode, which
is the same as Emacs-Lisp mode except for one command, LFD. In
Emacs-Lisp mode, LFD is an indentation command, as usual. In Lisp
Interaction mode, LFD is bound to `eval-print-last-sexp'. This
function reads the Lisp expression before point, evaluates it, and inserts
the value in printed representation before point.

Thus, the way to use the `*scratch*' buffer is to insert Lisp expressions
at the end, ending each one with LFD so that it will be evaluated.
The result is a complete typescript of the expressions you have evaluated
and their values.

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. `M-x lisp-interaction-mode' will put any buffer in Lisp
Interaction mode.

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File: emacs Node: External Lisp, Prev: Lisp Interaction, Up: Running

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. 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, a mode which has all the
special characteristics of Lisp mode and Shell mode (*Note 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' 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-send-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 Lisp Modes::.

▶1f◀
File: emacs Node: Abbrevs, Prev: Running, Up: Top, Next: Picture

Abbrevs
*******

An "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'. With this abbrev defined, you would be able to
get `find outer otter ' into the buffer by typing `f o o SPC'.

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.

A second kind of abbreviation facility is called the "dynamic
expansion". Dynamic abbrev expansion happens only when you give an
explicit command and the result of the expansion depends only on the
current contents of the buffer. *Note Dynamic Abbrevs::.

* Menu:

* 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.

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File: emacs Node: Defining Abbrevs, Prev: Abbrevs, Up: Abbrevs, Next: Expanding Abbrevs

Defining Abbrevs
================

`C-x +'
Define an abbrev to expand into some text before point
(`add-global-abbrev').
`C-x C-a'
Similar, but define an abbrev available only in the current major mode
(`add-mode-abbrev').
`C-x -'
Define a word in the buffer as an abbrev (`inverse-add-global-abbrev').
`C-x C-h'
Define a word in the buffer as a mode-specific abbrev
(`inverse-add-mode-abbrev').
`M-x kill-all-abbrevs'
After this command, there are no abbrev definitions in effect.

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 +'
(`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 + f o o RET'.

An argument of zero to `C-x +' means to use the contents of the
region as the expansion of the abbrev being defined.

The command `C-x C-a' (`add-mode-abbrev') is similar, but
defines a mode-specific abbrev. Mode specific abbrevs are active only in a
particular major mode. `C-x C-a' defines an abbrev for the major mode
in effect at the time `C-x C-a' is typed. The arguments work the same
as for `C-x +'.

If the text of the abbrev you want is already in the buffer instead of
the expansion, use command `C-x -' (`inverse-add-global-abbrev') instead of
`C-x +', or use `C-x C-h' (`inverse-add-mode-abbrev') instead of `C-x C-a'.
These commands are called "inverse" because they invert the meaning of the
argument found in the buffer and the argument read using the minibuffer.

To change the definition of an abbrev, just add the new definition. You
will be asked to confirm if the abbrev has a prior definition. To remove
an abbrev definition, give a negative argument to `C-x +' or `C-x
C-a'. You must choose the command to specify whether to kill a global
definition or a mode-specific definition for the current mode, since those
two definitions are independent for one abbrev.

`M-x kill-all-abbrevs' removes all the abbrev definitions there are.

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File: emacs Node: Expanding Abbrevs, Prev: Defining Abbrevs, Up: Abbrevs, Next: Editing Abbrevs

Controlling Abbrev Expansion
============================

An abbrev expands whenever it is present in the buffer just before point
and a self-inserting punctuation character (SPC, comma, etc.) is
typed. Most often the way an abbrev is used is to insert the abbrev
followed by punctuation.

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 two commands are used to control abbrev expansion:

`M-''
Separate a prefix from a following abbrev to be expanded
(`abbrev-prefix-mark').
`C-x ''
Expand the abbrev before point (`expand-abbrev').
This is effective even when Abbrev mode is not enabled.
`M-x unexpand-abbrev'
Undo last abbrev expansion.
`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 does work is to 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 minus sign 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 punctuation
character to expand the abbrev `cnst' into `construction'. The minus sign
is deleted at this point, because `M-'' left word for this to be done. The
resulting text 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 (replace
the expansion by the original abbrev text) with `M-x unexpand-abbrev'.
`C-_' (`undo') can also be used to undo the expansion; but first
it will undo the insertion of the following punctuation 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.

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File: emacs Node: Editing Abbrevs, Prev: Expanding Abbrevs, Up: Abbrevs, Next: Saving Abbrevs

Examining and Editing Abbrevs
=============================

`M-x list-abbrevs'
Print 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 is the abbrev. The number that appears is the number
of times the abbrev has been expanded. Emacs keeps track of this to help
you see which abbrevs you actually use, in case you decide to 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. This mode redefines the key `C-c C-c' to
install the abbrev definitions as specified in the buffer. The command
that does this is `edit-abbrevs-redefine'. Any abbrevs not described
in the buffer are eliminated when this is done.

`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.

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File: emacs Node: Saving Abbrevs, Prev: Editing Abbrevs, Up: Abbrevs, Next: Dynamic Abbrevs

Saving Abbrevs
==============

These commands allow you to keep abbrev definitions between editing
sessions.

`M-x write-abbrev-file'
Write a file describing all defined abbrevs.
`M-x read-abbrev-file'
Read such a file and define abbrevs as specified there.
`M-x quietly-read-abbrev-file'
Similar but do not display a message about what is going on.
`M-x define-abbrevs'
Define abbrevs from buffer.
`M-x insert-abbrevs'
Insert all abbrevs and their expansions into the buffer.

`M-x write-abbrev-file' reads a file name using the minibuffer and
writes a description of all current abbrev definitions into that file. The
text stored in the file looks like the output of `M-x list-abbrevs'.
This is used to save abbrev definitions for use in a later session.

`M-x read-abbrev-file' reads a file name using the minibuffer and
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, the file name used is the
value of 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.

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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').

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 the entire buffer
before point has been considered, the buffer after point is searched.

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.

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File: emacs Node: Picture, Prev: Abbrevs, Up: Top, Next: Sending Mail

Editing Pictures
****************

If you want to create 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 `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 in Picture mode most
frequently-used keys are rebound to commands 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, and
then you can use the `C-c C-c' command (`picture-mode-exit') to
restore that mode. `C-c C-c' also deletes spaces from the ends of
lines, unless given a numeric argument.

The commands used in Picture mode all work in other modes (provided the
`picture' library is loaded), but are not bound to keys except in
Picture mode. Note that 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 calls the value of the variable `picture-mode-hook'
as a function, with no arguments, if that value exists and is non-`nil'.

* 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.

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File: emacs Node: Basic Picture, Prev: Picture, Up: Picture, Next: Insert in 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', which is defined to move point one column to the
right, by 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.

Deletion and killing of text are replaced with erasure. DEL
(`picture-backward-clear-column') replaces the preceding character with a
space rather than removing it. `C-d' (`picture-clear-column') does the
same thing in a forward direction. `C-k' (`picture-clear-line') really
kills the contents of lines, but does not ever remove the newlines from the
buffer.

To do actual insertion, you must use special commands. `C-o'
(`picture-open-line') still creates a blank line, but does so 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.

Real deletion can be done with `C-w', or with `C-c C-d' (which is
defined as `delete-char', as `C-d' is in other modes), or with one
of the picture rectangle commands (*Note Rectangles in Picture::).

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File: emacs Node: Insert in Picture, Prev: Basic Picture, Up: Picture, Next: Tabs in Picture

Controlling Motion after Insert
===============================

Since "self-inserting" characters in Picture mode just 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. `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.

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File: emacs Node: Tabs in Picture, Prev: Insert in Picture, Up: Picture, Next: Rectangles in Picture

Picture Mode Tabs
=================

Two kinds of tab-like action are provided in Picture mode. Context-based
tabbing is done with `M-TAB' (`picture-tab-search'). 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 contains a string whose characters are
all considered interesting. 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.

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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 (`picture-clear-rectangle'). With
argument, kill it.
`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 take the rectangle from 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.

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 is different 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.

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File: emacs Node: Sending Mail, Prev: Picture, Up: Top, Next: Rmail

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-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-c C-c'
In Mail mode, send the message and switch to another 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.

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-buffer' (*Note Misc Buffer::).

* Menu:

* Format: Mail Format. Format of the mail being composed.
* Headers: Mail Headers. Details of allowed mail header fields.
* Mode: Mail Mode. Special commands for editing mail being composed.

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