Fresh Fish 4/FreshFish_May-June1994.bin/bbs/gnu/emacs-18.59-src.lha/src/amiga/emacs-18.59/emacs-18.59-amiga/info/emacs-12

GNU Info File | 1992-10-31 | 48.8 KB | 1,216 lines

This is Info file ../info/emacs, produced by Makeinfo-1.49 from the
input file emacs.texi.

   This file documents the GNU Emacs editor.

   Copyright (C) 1985, 1986, 1988, 1992 Richard M. Stallman.

   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
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 General Public License" may be included in a
translation approved by the author instead of in the original English.


File: emacs,  Node: Init Examples,  Next: Terminal Init,  Prev: Init Syntax,  Up: Init File

Init File Examples
------------------

   Here are some examples of doing certain commonly desired things with
Lisp expressions:

   * Make TAB in C mode just insert a tab if point is in the middle of a
     line.

          (setq c-tab-always-indent nil)

     Here we have a variable whose value is normally `t' for `true' and
     the alternative is `nil' for `false'.

   * Make searches case sensitive by default (in all buffers that do not
     override this).

          (setq-default case-fold-search nil)

     This sets the default value, which is effective in all buffers
     that do not have local values for the variable.  Setting
     `case-fold-search' with `setq' affects only the current buffer's
     local value, which is not what you probably want to do in an init
     file.

   * Make Text mode the default mode for new buffers.

          (setq default-major-mode 'text-mode)

     Note that `text-mode' is used because it is the command for
     entering the mode we want.  A single-quote is written before it to
     make a symbol constant; otherwise, `text-mode' would be treated as
     a variable name.

   * Turn on Auto Fill mode automatically in Text mode and related
     modes.

          (setq text-mode-hook
            '(lambda () (auto-fill-mode 1)))

     Here we have a variable whose value should be a Lisp function.  The
     function we supply is a list starting with `lambda', and a single
     quote is written in front of it to make it (for the purpose of this
     `setq') a list constant rather than an expression.  Lisp functions
     are not explained here, but for mode hooks it is enough to know
     that `(auto-fill-mode 1)' is an expression that will be executed
     when Text mode is entered, and you could replace it with any other
     expression that you like, or with several expressions in a row.

          (setq text-mode-hook 'turn-on-auto-fill)

     This is another way to accomplish the same result.
     `turn-on-auto-fill' is a symbol whose function definition is
     `(lambda () (auto-fill-mode 1))'.

   * Load the installed Lisp library named `foo' (actually a file
     `foo.elc' or `foo.el' in a standard Emacs directory).

          (load "foo")

     When the argument to `load' is a relative pathname, not starting
     with `/' or `~', `load' searches the directories in `load-path'
     (*note Loading::.).

   * Load the compiled Lisp file `foo.elc' from your home directory.

          (load "~/foo.elc")

     Here an absolute file name is used, so no searching is done.

   * Rebind the key `C-x l' to run the function `make-symbolic-link'.

          (global-set-key "\C-xl" 'make-symbolic-link)

     or

          (define-key global-map "\C-xl" 'make-symbolic-link)

     Note once again the single-quote used to refer to the symbol
     `make-symbolic-link' instead of its value as a variable.

   * Do the same thing for C mode only.

          (define-key c-mode-map "\C-xl" 'make-symbolic-link)

   * Redefine all keys which now run `next-line' in Fundamental mode so
     that they run `forward-line' instead.

          (substitute-key-definition 'next-line 'forward-line
                                     global-map)

   * Make `C-x C-v' undefined.

          (global-unset-key "\C-x\C-v")

     One reason to undefine a key is so that you can make it a prefix.
     Simply defining `C-x C-v ANYTHING' would make `C-x C-v' a prefix,
     but `C-x C-v' must be freed of any non-prefix definition first.

   * Make `$' have the syntax of punctuation in Text mode. Note the use
     of a character constant for `$'.

          (modify-syntax-entry ?\$ "." text-mode-syntax-table)

   * Enable the use of the command `eval-expression' without
     confirmation.

          (put 'eval-expression 'disabled nil)


File: emacs,  Node: Terminal Init,  Next: Debugging Init,  Prev: Init Examples,  Up: Init File

Terminal-specific Initialization
--------------------------------

   Each terminal type can have a Lisp library to be loaded into Emacs
when it is run on that type of terminal.  For a terminal type named
TERMTYPE, the library is called `term/TERMTYPE' and it is found by
searching the directories `load-path' as usual and trying the suffixes
`.elc' and `.el'.  Normally it appears in the subdirectory `term' of
the directory where most Emacs libraries are kept.

   The usual purpose of the terminal-specific library is to define the
escape sequences used by the terminal's function keys using the library
`keypad.el'.  See the file `term/vt100.el' for an example of how this
is done.

   When the terminal type contains a hyphen, only the part of the name
before the first hyphen is significant in choosing the library name.
Thus, terminal types `aaa-48' and `aaa-30-rv' both use the library
`term/aaa'.  The code in the library can use `(getenv "TERM")' to find
the full terminal type name.

   The library's name is constructed by concatenating the value of the
variable `term-file-prefix' and the terminal type.  Your `.emacs' file
can prevent the loading of the terminal-specific library by setting
`term-file-prefix' to `nil'.

   The value of the variable `term-setup-hook', if not `nil', is called
as a function of no arguments at the end of Emacs initialization, after
both your `.emacs' file and any terminal-specific library have been
read in.  You can set the value in the `.emacs' file to override part
of any of the terminal-specific libraries and to define initializations
for terminals that do not have a library.


File: emacs,  Node: Debugging Init,  Prev: Terminal Init,  Up: Init File

Debugging Your `.emacs' File
----------------------------

   Ordinarily, Emacs traps errors that occur while reading `.emacs'.
This is convenient, most of the time, because it means you can still get
an Emacs in which you can edit.  But it causes inconvenience because
there is no way to enter the debugger if there is an error.

   But you can run the `.emacs' file explicitly in an Emacs that is
already set up, and debug errors at that time.

     M-x set-variable
     debug-on-error
     t
     M-x load-file
     ~/.emacs

   In Emacs 19, use the `-debug-init' option if you want errors in
`.emacs' to enter the debugger.


File: emacs,  Node: Quitting,  Next: Lossage,  Prev: Customization,  Up: Top

Quitting and Aborting
=====================

`C-g'
     Quit.  Cancel running or partially typed command.

`C-]'
     Abort innermost recursive editing level and cancel the command
     which invoked it (`abort-recursive-edit').

`M-x top-level'
     Abort all recursive editing levels that are currently executing.

`C-x u'
     Cancel an already-executed command, usually (`undo').

   There are two ways of cancelling commands which are not finished
executing: "quitting" with `C-g', and "aborting" with `C-]' or `M-x
top-level'.  Quitting is cancelling a partially typed command or one
which is already running.  Aborting is getting out of a recursive
editing level and cancelling the command that invoked the recursive
edit.

   Quitting with `C-g' is used for getting rid of a partially typed
command, or a numeric argument that you don't want.  It also stops a
running command in the middle in a relatively safe way, so you can use
it if you accidentally give a command which takes a long time.  In
particular, it is safe to quit out of killing; either your text will
ALL still be there, or it will ALL be in the kill ring (or maybe both).
 Quitting an incremental search does special things documented under
searching; in general, it may take two successive `C-g' characters to
get out of a search.  `C-g' works by setting the variable `quit-flag' to
`t' the instant `C-g' is typed; Emacs Lisp checks this variable
frequently and quits if it is non-`nil'.  `C-g' is only actually
executed as a command if it is typed while Emacs is waiting for input.

   If you quit twice in a row before the first `C-g' is recognized, you
activate the "emergency escape" feature and return to the shell. *Note
Emergency Escape::.

   Aborting with `C-]' (`abort-recursive-edit') is used to get out of a
recursive editing level and cancel the command which invoked it.
Quitting with `C-g' does not do this, and could not do this, because it
is used to cancel a partially typed command within the recursive
editing level.  Both operations are useful.  For example, if you are in
the Emacs debugger (*note Lisp Debug::.) and have typed `C-u 8' to
enter a numeric argument, you can cancel that argument with `C-g' and
remain in the debugger.

   The command `M-x top-level' is equivalent to "enough" `C-]' commands
to get you out of all the levels of recursive edits that you are in.
`C-]' gets you out one level at a time, but `M-x top-level' goes out
all levels at once.  Both `C-]' and `M-x top-level' are like all other
commands, and unlike `C-g', in that they are effective only when Emacs
is ready for a command.  `C-]' is an ordinary key and has its meaning
only because of its binding in the keymap. *Note Recursive Edit::.

   `C-x u' (`undo') is not strictly speaking a way of cancelling a
command, but you can think of it as cancelling a command already
finished executing.  *Note Undo::.


File: emacs,  Node: Lossage,  Next: Bugs,  Prev: Quitting,  Up: Top

Dealing with Emacs Trouble
==========================

   This section describes various conditions in which Emacs fails to
work, and how to recognize them and correct them.

* Menu:

* Stuck Recursive::    `[...]' in mode line around the parentheses
* Screen Garbled::     Garbage on the screen
* Text Garbled::       Garbage in the text
* Unasked-for Search:: Spontaneous entry to incremental search
* Emergency Escape::   Emergency escape--
                        What to do if Emacs stops responding
* Total Frustration::  When you are at your wits' end.


File: emacs,  Node: Stuck Recursive,  Next: Screen Garbled,  Prev: Lossage,  Up: Lossage

Recursive Editing Levels
------------------------

   Recursive editing levels are important and useful features of Emacs,
but they can seem like malfunctions to the user who does not understand
them.

   If the mode line has square brackets `[...]' around the parentheses
that contain the names of the major and minor modes, you have entered a
recursive editing level.  If you did not do this on purpose, or if you
don't understand what that means, you should just get out of the
recursive editing level.  To do so, type `M-x top-level'.  This is
called getting back to top level.  *Note Recursive Edit::.


File: emacs,  Node: Screen Garbled,  Next: Text Garbled,  Prev: Stuck Recursive,  Up: Lossage

Garbage on the Screen
---------------------

   If the data on the screen looks wrong, the first thing to do is see
whether the text is really wrong.  Type `C-l', to redisplay the entire
screen.  If it appears correct after this, the problem was entirely in
the previous screen update.

   Display updating problems often result from an incorrect termcap
entry for the terminal you are using.  The file `etc/TERMS' in the Emacs
distribution gives the fixes for known problems of this sort. `INSTALL'
contains general advice for these problems in one of its sections.
Very likely there is simply insufficient padding for certain display
operations.  To investigate the possibility that you have this sort of
problem, try Emacs on another terminal made by a different manufacturer.
If problems happen frequently on one kind of terminal but not another
kind, it is likely to be a bad termcap entry, though it could also be
due to a bug in Emacs that appears for terminals that have or that lack
specific features.


File: emacs,  Node: Text Garbled,  Next: Unasked-for Search,  Prev: Screen Garbled,  Up: Lossage

Garbage in the Text
-------------------

   If `C-l' shows that the text is wrong, try undoing the changes to it
using `C-x u' until it gets back to a state you consider correct.  Also
try `C-h l' to find out what command you typed to produce the observed
results.

   If a large portion of text appears to be missing at the beginning or
end of the buffer, check for the word `Narrow' in the mode line. If it
appears, the text is still present, but marked off-limits. To make it
visible again, type `C-x w'.  *Note Narrowing::.


File: emacs,  Node: Unasked-for Search,  Next: Emergency Escape,  Prev: Text Garbled,  Up: Lossage

Spontaneous Entry to Incremental Search
---------------------------------------

   If Emacs spontaneously displays `I-search:' at the bottom of the
screen, it means that the terminal is sending `C-s' and `C-q' according
to the poorly designed `xon/xoff' "flow control" protocol.  You should
try to prevent this by putting the terminal in a mode where it will not
use flow control or giving it enough padding that it will never send a
`C-s'.  If that cannot be done, you must tell Emacs to expect flow
control to be used, until you can get a properly designed terminal.

   Information on how to do these things can be found in the file
`INSTALL' in the Emacs distribution.


File: emacs,  Node: Emergency Escape,  Next: Total Frustration,  Prev: Unasked-for Search,  Up: Lossage

Emergency Escape
----------------

   Because at times there have been bugs causing Emacs to loop without
checking `quit-flag', a special feature causes Emacs to be suspended
immediately if you type a second `C-g' while the flag is already set,
so you can always get out of GNU Emacs.  Normally Emacs recognizes and
clears `quit-flag' (and quits!) quickly enough to prevent this from
happening.

   When you resume Emacs after a suspension caused by multiple `C-g', it
asks two questions before going back to what it had been doing:

     Auto-save? (y or n)
     Abort (and dump core)? (y or n)

Answer each one with `y' or `n' followed by RET.

   Saying `y' to `Auto-save?' causes immediate auto-saving of all
modified buffers in which auto-saving is enabled.

   Saying `y' to `Abort (and dump core)?' causes an illegal instruction
to be executed, dumping core.  This is to enable a wizard to figure out
why Emacs was failing to quit in the first place.  Execution does not
continue after a core dump.  If you answer `n', execution does
continue.  With luck, GNU Emacs will ultimately check `quit-flag' and
quit normally. If not, and you type another `C-g', it is suspended
again.

   If Emacs is not really hung, just slow, you may invoke the double
`C-g' feature without really meaning to.  Then just resume and answer
`n' to both questions, and you will arrive at your former state.
Presumably the quit you requested will happen soon.

   The double-`C-g' feature may be turned off when Emacs is running
under a window system, since the window system always enables you to
kill Emacs or to create another window and run another program.


File: emacs,  Node: Total Frustration,  Prev: Emergency Escape,  Up: Lossage

Help for Total Frustration
--------------------------

   If using Emacs (or something else) becomes terribly frustrating and
none of the techniques described above solve the problem, Emacs can
still help you.

   First, if the Emacs you are using is not responding to commands, type
`C-g C-g' to get out of it and then start a new one.

   Second, type `M-x doctor RET'.

   The doctor will make you feel better.  Each time you say something to
the doctor, you must end it by typing RET RET.  This lets the doctor
know you are finished.


File: emacs,  Node: Bugs,  Next: Version 19,  Prev: Lossage,  Up: Top

Reporting Bugs
==============

   Sometimes you will encounter a bug in Emacs.  Although we cannot
promise we can or will fix the bug, and we might not even agree that it
is a bug, we want to hear about bugs you encounter in case we do want
to fix them.

   To make it possible for us to fix a bug, you must report it.  In
order to do so effectively, you must know when and how to do it.

When Is There a Bug
-------------------

   If Emacs executes an illegal instruction, or dies with an operating
system error message that indicates a problem in the program (as
opposed to something like "disk full"), then it is certainly a bug.

   If Emacs updates the display in a way that does not correspond to
what is in the buffer, then it is certainly a bug.  If a command seems
to do the wrong thing but the problem corrects itself if you type
`C-l', it is a case of incorrect display updating.

   Taking forever to complete a command can be a bug, but you must make
certain that it was really Emacs's fault.  Some commands simply take a
long time.  Type `C-g' and then `C-h l' to see whether the input Emacs
received was what you intended to type; if the input was such that you
KNOW it should have been processed quickly, report a bug.  If you don't
know whether the command should take a long time, find out by looking
in the manual or by asking for assistance.

   If a command you are familiar with causes an Emacs error message in a
case where its usual definition ought to be reasonable, it is probably a
bug.

   If a command does the wrong thing, that is a bug.  But be sure you
know for certain what it ought to have done.  If you aren't familiar
with the command, or don't know for certain how the command is supposed
to work, then it might actually be working right.  Rather than jumping
to conclusions, show the problem to someone who knows for certain.

   Finally, a command's intended definition may not be best for editing
with.  This is a very important sort of problem, but it is also a
matter of judgment.  Also, it is easy to come to such a conclusion out
of ignorance of some of the existing features.  It is probably best not
to complain about such a problem until you have checked the
documentation in the usual ways, feel confident that you understand it,
and know for certain that what you want is not available.  If you are
not sure what the command is supposed to do after a careful reading of
the manual, check the index and glossary for any terms that may be
unclear.  If you still do not understand, this indicates a bug in the
manual.  The manual's job is to make everything clear.  It is just as
important to report documentation bugs as program bugs.

   If the on-line documentation string of a function or variable
disagrees with the manual, one of them must be wrong, so report the bug.

How to Report a Bug
-------------------

   When you decide that there is a bug, it is important to report it
and to report it in a way which is useful.  What is most useful is an
exact description of what commands you type, starting with the shell
command to run Emacs, until the problem happens.  Always include the
version number of Emacs that you are using; type `M-x emacs-version' to
print this.

   The most important principle in reporting a bug is to report FACTS,
not hypotheses or categorizations.  It is always easier to report the
facts, but people seem to prefer to strain to posit explanations and
report them instead.  If the explanations are based on guesses about
how Emacs is implemented, they will be useless; we will have to try to
figure out what the facts must have been to lead to such speculations.
Sometimes this is impossible.  But in any case, it is unnecessary work
for us.

   For example, suppose that you type `C-x C-f /glorp/baz.ugh RET',
visiting a file which (you know) happens to be rather large, and Emacs
prints out `I feel pretty today'.  The best way to report the bug is
with a sentence like the preceding one, because it gives all the facts
and nothing but the facts.

   Do not assume that the problem is due to the size of the file and
say, "When I visit a large file, Emacs prints out `I feel pretty
today'." This is what we mean by "guessing explanations".  The problem
is just as likely to be due to the fact that there is a `z' in the file
name.  If this is so, then when we got your report, we would try out
the problem with some "large file", probably with no `z' in its name,
and not find anything wrong.  There is no way in the world that we
could guess that we should try visiting a file with a `z' in its name.

   Alternatively, the problem might be due to the fact that the file
starts with exactly 25 spaces.  For this reason, you should make sure
that you inform us of the exact contents of any file that is needed to
reproduce the bug.  What if the problem only occurs when you have typed
the `C-x C-a' command previously?  This is why we ask you to give the
exact sequence of characters you typed since starting to use Emacs.

   You should not even say "visit a file" instead of `C-x C-f' unless
you know that it makes no difference which visiting command is used.
Similarly, rather than saying "if I have three characters on the line,"
say "after I type `RET A B C' RET C-p," if that is the way you entered
the text.

   If you are not in Fundamental mode when the problem occurs, you
should say what mode you are in.

   If the manifestation of the bug is an Emacs error message, it is
important to report not just the text of the error message but a
backtrace showing how the Lisp program in Emacs arrived at the error.
To make the backtrace, you must execute the Lisp expression `(setq
debug-on-error t)' before the error happens (that is to say, you must
execute that expression and then make the bug happen).  This causes the
Lisp debugger to run (*note Lisp Debug::.).  The debugger's backtrace
can be copied as text into the bug report.  This use of the debugger is
possible only if you know how to make the bug happen again.  Do note
the error message the first time the bug happens, so if you can't make
it happen again, you can report at least that.

   Check whether any programs you have loaded into the Lisp world,
including your `.emacs' file, set any variables that may affect the
functioning of Emacs.  Also, see whether the problem happens in a
freshly started Emacs without loading your `.emacs' file (start Emacs
with the `-q' switch to prevent loading the init file.)  If the problem
does NOT occur then, it is essential that we know the contents of any
programs that you must load into the Lisp world in order to cause the
problem to occur.

   If the problem does depend on an init file or other Lisp programs
that are not part of the standard Emacs system, then you should make
sure it is not a bug in those programs by complaining to their
maintainers first. After they verify that they are using Emacs in a way
that is supposed to work, they should report the bug.

   If you can tell us a way to cause the problem without visiting any
files, please do so.  This makes it much easier to debug.  If you do
need files, make sure you arrange for us to see their exact contents.
For example, it can often matter whether there are spaces at the ends
of lines, or a newline after the last line in the buffer (nothing ought
to care whether the last line is terminated, but tell that to the bugs).

   The easy way to record the input to Emacs precisely is to write a
dribble file; execute the Lisp expression

     (open-dribble-file "~/dribble")

using `Meta-ESC' or from the `*scratch*' buffer just after starting
Emacs.  From then on, all Emacs input will be written in the specified
dribble file until the Emacs process is killed.

   For possible display bugs, it is important to report the terminal
type (the value of environment variable `TERM'), the complete termcap
entry for the terminal from `/etc/termcap' (since that file is not
identical on all machines), and the output that Emacs actually sent to
the terminal. The way to collect this output is to execute the Lisp
expression

     (open-termscript "~/termscript")

using `Meta-ESC' or from the `*scratch*' buffer just after starting
Emacs.  From then on, all output from Emacs to the terminal will be
written in the specified termscript file as well, until the Emacs
process is killed.  If the problem happens when Emacs starts up, put
this expression into your `.emacs' file so that the termscript file will
be open when Emacs displays the screen for the first time.  Be warned:
it is often difficult, and sometimes impossible, to fix a
terminal-dependent bug without access to a terminal of the type that
stimulates the bug.

   The address for reporting bugs is

GNU Emacs Bugs
Free Software Foundation
675 Mass Ave
Cambridge, MA 02139

or send email either to `[e-mail]' (Internet) or
to `uunet!prep.ai.mit.edu!bug-gnu-emacs' (Usenet).

   Once again, we do not promise to fix the bug; but if the bug is
serious, or ugly, or easy to fix, chances are we will want to.


File: emacs,  Node: Version 19,  Next: Manifesto,  Prev: Bugs,  Up: Top

Version 19 Antenews
*******************

   This chapter prematurely describes new features of Emacs 19, in
anticipation of its release.  We have included this so that the version
18 manuals don't become obsolete as soon as Emacs 19 comes out.  This
list mentions only features that would belong in `The GNU Emacs
Manual'; changes relevant to Emacs Lisp programming will be documented
in the next revision of `The GNU Emacs Lisp Manual'.

* Menu:

* Basic Changes::      Changes every user must know.
* New Facilities::      Changes every user will want to know.
* Binding Changes::      Ordinary commands that have been moved.  Important!.
* Changed Commands::      Ordinary commands that have new features.  Important!
* M-x Changes::          Changes in commands you run with `M-x'.  Important!
* New Commands::      Commands that have been added
                that we expect many users to want to use.
* Search Changes::      Changes in incremental search.  Some are important.

The rest of the changes you can pretty much ignore unless you are interested.

* Filling Changes::      Changes in fill commands.
* TeX Mode Changes::      Changes in the commands for editing TeX files
                and running TeX.
* Shell Changes::      Major changes in all the modes that run subprograms.
* Spell Changes::      These commands now use ispell instead of spell.
* Tags Changes::      Changes in Tags facility.
* Mail Changes::      Changes in both Sendmail mode and Rmail mode.
* Info Changes::      New commands in Info.
* Dired Changes::      Powerful new features in Dired.
* GNUS::          An alternative news reader.
* Calendar/Diary::      The calendar feature now lets you move to different
                dates and convert to and from other calendars.
              You can also display related entries from your diary
                file.
* Version Control::      A convenient interface to RCS or SCCS.
* Emerge::          A new feature for merging files interactively.
* Debuggers::          Running debuggers (GDB, DBX, SDB) under Emacs.
* Other New Modes::      Miscellaneous new and changed major modes.
* Key Sequence Changes::  You can now bind key sequences that include function
                keys and mouse clicks.
* Hook Changes::      Hook variables have been renamed more systematically.


File: emacs,  Node: Basic Changes,  Next: New Facilities,  Up: Version 19

Basic Changes
=============

   We have made changes to help Emacs use fewer resources and make it
less likely to become irreparably hung.  While these changes don't
alter the commands of Emacs, they are important enough to be worth
mentioning.

   You can quit with `C-g' while Emacs is waiting to read or write a
file--provided the operating system will allow you to interrupt the
system call that is hung.  (Unfortunately, most NFS implementations
won't allow interruption.)

   When you kill buffers, Emacs now returns memory to the operating
system, thus reducing the size of the Emacs process.  The space that
you free up by killing buffers can now be reused for other buffers no
matter what their sizes, or reused by other processes if Emacs doesn't
need it.

Multiple X Windows
------------------

   When using X windows, you can now create more than one window at the
X level.  Each X window displays a "frame" which can contain one or
several Emacs windows.  Each frame has its own echo area and normally
its own minibuffer.  (To avoid confusion, we reserve the word "window"
for the subdivisions that Emacs implements, and never use it to refer
to a frame.)  The easiest way to create additional frames is with the
`C-x 5' prefix character (*note New Everyday Commands: New Commands.).

   Emacs windows can now have scroll bars; use the `scroll-bar-mode'
command to turn scroll bars on or off.  With no argument, it toggles the
use of scroll bars.  With an argument, it turns use of scroll bars on if
and only if the argument is positive.  This command applies to all
frames, including frames yet to be created.  (You can control scroll
bars on a frame by frame basis by writing a Lisp program.)

Undo Improvements
-----------------

   Undoing a deletion now puts the cursor position where it was just
before the deletion.

Auto Save Improvements
----------------------

   Emacs now does garbage collection and auto saving while it is waiting
for input, which often avoids the need to do these things while you are
typing.  The variable `auto-save-timeout' says how many seconds Emacs
should wait, after you stop typing, before it does an auto save and
perhaps also a garbage collection.  (The actual time period varies also
according to the size of the buffer--longer for longer buffers, since
auto saving itself is slower for long buffers.)  This way, Emacs does
not interrupt or delay your typing.

   In Emacs 18, when auto saving detects that a buffer has shrunk
greatly, it refrains from auto saving that buffer and displays a
warning.  In version 19, it also turns off Auto Save mode in that
buffer, so that you won't get the same warning repeatedly.  If you
reenable Auto Save mode in that buffer, Emacs will start saving it
again despite the shrinkage.

   In Emacs 19, `revert-buffer' no longer offers to revert from the
latest auto-save file.  That option hasn't been very useful since the
change to keep more undo information.

   The command `recover-file' no longer turns off Auto Save mode.

File Local Variables
--------------------

   The user option for controlling whether files can set local
variables is called `enable-local-variables' in Emacs 19, rather than
`inhibit-local-variables'.  A value of `t' means local-variables lists
are obeyed; `nil' means they are ignored; anything else means query the
user.


File: emacs,  Node: New Facilities,  Next: Binding Changes,  Prev: Basic Changes,  Up: Version 19

New Basic Facilities
====================

   You can now get back recent minibuffer inputs conveniently.  While in
the minibuffer, type `M-p' (`previous-history-element') to fetch the
next earlier minibuffer input, and use `M-n' (`next-history-element')
to fetch the next later input.

   There are also commands to search forward or backward through the
history.  As of this writing, they search for history elements that
match a regular expression that you specify with the minibuffer. `M-r'
(`previous-matching-history-element') searches older elements in the
history, while `M-s' (`next-matching-history-element') searches newer
elements.  By special dispensation, these commands can always use the
minibuffer to read their arguments even though you are already in the
minibuffer when you issue them.

   We may have changed the precise way these commands work by the time
you use Emacs 19.  Perhaps they will search for a match for the string
given so far in the minibuffer; perhaps they will search for a literal
match rather than a regular expression match; perhaps they will only
accept matches at the beginning of a history element; perhaps they will
read the string to search for incrementally like `C-s'.  We want to
choose an interface that is convenient, flexible and natural, and these
goals are somewhat contradictory.  To find out what interface is
actually available, type `C-h f previous-matching-history-element'.

   The history feature is available for all uses of the minibuffer, but
there are separate history lists for different kinds of input.  For
example, there is a list for file names, used by all the commands that
read file names.  There is a list for arguments of commands like
`query-replace'.  There are also very specific history lists, such as
the one that `compile' uses for compilation commands.

Remote File Access
------------------

   You can refer to files on other machines using a special file name
syntax:

     /HOST:FILENAME
     /USER@HOST:FILENAME

   When you do this, Emacs uses the FTP program to read and write files
on the specified host.  It logs in through FTP using your user name or
the name USER.  It may ask you for a password from time to time; this
is used for logging in on HOST.

Using Flow Control
------------------

   There is now a convenient way to enable flow control when your
terminal or your connection won't work without it.  Suppose you want to
do this on VT-100 and H19 terminals; put the following in your `.emacs'
file:

     (evade-flow-control-on "vt100" "h19")

   When flow control is enabled, you must type `C-\' to get the effect
of a `C-s', and type `C-^' to get the effect of a `C-q'.

Controlling Backup File Names
-----------------------------

   The default setting of the Lisp variable `version-control' now comes
from the environment variable `VERSION_CONTROL'.  Thus, you can select
a style of backup file naming for Emacs and other GNU utilities all
together.


File: emacs,  Node: Binding Changes,  Next: Changed Commands,  Prev: New Facilities,  Up: Version 19

Changed Key Bindings
====================

`M-{'
     This is the new key sequence for `backward-paragraph'.  The old key
     sequence for this, `M-[', is now undefined by default.

     The reason for this change is to avoid conflict with the sequences
     that function keys send on most terminals.

`M-}'
     This is the new key sequence for `forward-paragraph'.  The old key
     sequence for this, `M-]', is now undefined by default.

     We changed this to go along with `M-{'.

`C-x C-u'
`C-x C-l'
     The two commands, `C-x C-u' (`upcase-region') and `C-x C-l'
     (`downcase-region'), are now disabled by default; these keys seem
     to be often hit by accident, and can be quite destructive if their
     effects are not noticed immediately.

`C-x 3'
     `C-x 3' is now the key binding for `split-window-horizontally',
     which splits a window into two side-by-side windows.  This used to
     be `C-x 5'.

``C-x 4 C-o''
     This key now runs `display-buffer', which displays a specified
     buffer in another window without selecting it.

`M-g'
     `M-g' is now undefined.  It used to run the command `fill-region'.
     This command used to be run more often by mistake than on purpose.

`C-x a'
`C-x n'
`C-x r'
     Three new prefix keys have been created to make many of the `C-x'
     commands more systematic: `C-x a', `C-x n' and `C-x r'. `C-x a' is
     used for abbreviation commands, `C-x n' for commands pertaining to
     narrowing, and `C-x r' for register and rectangle commands.  These
     are the new bindings, in detail:

    `C-x a l'
          `add-mode-abbrev' (previously `C-x C-a').

    `C-x a g'
          `add-global-abbrev' (previously `C-x +').

    `C-x a i g'
          `inverse-add-mode-abbrev' (previously `C-x C-h').

    `C-x a i l'
          `inverse-add-global-abbrev' (previously `C-x -').

    `C-x a e'
          `expand-abbrev' (previously `C-x '').

    `C-x n n'
          `narrow-to-region' (previously `C-x n').

    `C-x n p'
          `narrow-to-page' (previously `C-x p').

    `C-x n w'
          `widen' (previously `C-x w').

    `C-x r C-SPC'
          `point-to-register' (previously `C-x /').

    `C-x r SPC'
          Also `point-to-register' (previously `C-x /').

    `C-x r j'
          `jump-to-register' (previously `C-x j').

    `C-x r s'
          `copy-to-register' (previously `C-x x').

    `C-x r i'
          `insert-register' (previously `C-x g').

    `C-x r r'
          `copy-rectangle-to-register' (previously `C-x r').

    `C-x r k'
          `kill-rectangle' (no previous key binding).

    `C-x r y'
          `yank-rectangle' (no previous key binding).

    `C-x r o'
          `open-rectangle' (no previous key binding).

    `C-x r f'
          `frame-configuration-to-register' (a new command) saves the
          state of all windows in all frames. Use `C-x r j' to restore
          the configuration.

    `C-x r w'
          `window-configuration-to-register' (a new command) saves the
          state of all windows in the selected  frame. Use `C-x r j' to
          restore the configuration.

     The old key bindings `C-x /', `C-x j', `C-x x' and `C-x g' have
     not yet been removed.  The other old key bindings listed have been
     removed.  The old key binding `C-x a', which was
     `append-to-buffer', was removed to make way for a prefix key; now
     `append-to-buffer' has no keybinding.

`C-x v'
     `C-x v' is a new prefix character, used for version control
     commands. *Note Version Control::.


File: emacs,  Node: Changed Commands,  Next: M-x Changes,  Prev: Binding Changes,  Up: Version 19

Changed Everyday Commands
=========================

`C-o'
     When you have a fill prefix, the command `C-o' inserts the prefix
     on the newly created line.

`M-^'
     When you have a fill prefix, the command `M-^' deletes the prefix
     (if it occurs) after the newline that it deletes.

`M-z'
     The `M-z' command (`zap-to-char') now kills through the target
     character.  In version 18, it killed up to but not including the
     target character.

`M-!'
     The command `M-!' (`shell-command') now runs the specified shell
     command asynchronously if it ends in `&', just as the shell does.

`C-x 2'
     The `C-x 2' command (`split-window-vertically') now tries to avoid
     scrolling by putting point in whichever window happens to contain
     the screen line the cursor is already on.  If you don't like this,
     you can turn it off by setting `split-window-keep-point' to `nil'.

`C-x s'
     The `C-x s' command (`save-some-buffers') now gives you more
     options when it asks whether to save a particular buffer.  The
     options are analogous to those of `query-replace'.  Here they are:

    `y'
          Save this buffer and ask about the rest of the buffers.

    `n'
          Don't save this buffer, but ask about the rest of the buffers.

    `!'
          Save this buffer and all the rest with no more questions.

    `ESC'
          Terminate `save-some-buffers' without any more saving.

    `.'
          Save only this buffer, then exit `save-some-buffers' without
          even asking about other buffers.

    `C-r'
          View the buffer that you are currently being asked about.
          When you exit View mode, you get back to `save-some-buffers',
          which asks the question again.

    `C-h'
          Display a help message about these options.

`C-x C-v'
     This command (`find-alternate-file') now inserts the entire current
     file name in the minibuffer.  This is convenient if you made a
     small mistake in typing it.  Point goes after the last slash,
     before the last file name component, so if you want to replace it
     entirely, you can use `C-k' right away to delete it.

`C-M-f'
     Expression and list commands such as `C-M-f' now ignore parentheses
     within comments in Lisp mode.


File: emacs,  Node: M-x Changes,  Next: New Commands,  Prev: Changed Commands,  Up: Version 19

Changes in Common `M-x' Commands
================================

`M-x make-symbolic-link'
     This command now does not expand its second argument.  This lets
     you make a link with a target that is a relative file name.

`M-x add-change-log-entry'
`C-x 4 a'
     These commands now automatically insert the name of the file and
     often the name of the function that you changed.  They also handle
     grouping of entries.

     There is now a special major mode for editing `ChangeLog' files.
     It makes filling work conveniently.  Each bunch of grouped entries
     is one paragraph, and each collection of entries from one person
     on one day is considered a page.

`M-x compare-windows'
     With a prefix argument, `compare-windows' ignores changes in
     whitespace.  If the variable `compare-ignore-case' is non-`nil',
     it ignores differences in case as well.

`M-x view-buffer'
`M-x view-file'
     The View commands (such as `M-x view-buffer' and `M-x view-file')
     no longer use recursive edits; instead, they switch temporarily to
     a different major mode (View mode) specifically designed for
     moving around through a buffer without editing it.

`M-x manual-entry'
     `M-x manual-entry' now uses View mode for the buffer showing the
     man page.

`M-x compile'
     You can repeat any previous `compile' conveniently using the
     minibuffer history commands, while in the minibuffer entering the
     compilation command.

     While a compilation is going on, the string `Compiling' appears in
     the mode line.  When this string disappears, the compilation is
     finished.

     The buffer of compiler messages is in Compilation mode.  This mode
     provides the keys SPC and DEL to scroll by screenfuls, and `M-n'
     and `M-p' to move to the next or previous error message. You can
     also use `M-{' and `M-}' to move up or down to an error message
     for a different source file.  Use `C-c C-c' on any error message
     to find the corresponding source code.

     Emacs 19 has a more general parser for compiler messages.  For
     example, it can understand messages from lint, and from certain C
     compilers whose error message format is unusual.


File: emacs,  Node: New Commands,  Next: Search Changes,  Prev: M-x Changes,  Up: Version 19

New Everyday Commands
=====================

`C-z'
     When you are using X windows, `C-z' (`iconify-frame') now
     iconifies the current frame.

`C-M-l'
     The `C-M-l' command (`reposition-window') scrolls the current
     window heuristically in a way designed to get useful information
     onto the screen.  For example, in a Lisp file, this command tries
     to get the entire current defun onto the screen if possible.

`C-M-r'
     The `C-M-r' key now runs the command `isearch-backward-regexp',
     which does reverse incremental regexp search.

`C-x 5'
     The prefix key `C-x 5' is analogous to `C-x 4', with parallel
     subcommands.  The difference is that `C-x 5' commands create a new
     frame rather than just a new window.

`C-x 5 C-f'
`C-x 5 b'
     These new commands switch to a specified file or buffer in a new
     frame (when using X windows).  The commands' names are
     `find-file-other-frame' and `switch-to-buffer-other-frame'.

`C-x 5 m'
     Start outgoing mail in another frame (`mail-other-frame').

`C-x 5 .'
     Find a tag in another frame (`find-tag-other-frame').

`C-x 4 r'
     This is now `find-file-read-only-other-window'.

arrow keys
     The arrow keys now have default bindings to move in the appropriate
     directions.

`C-h C-f'
`C-h C-k'
     These new help commands enter Info and display the node for a given
     Emacs function name or key sequence, respectively.

`M-a'
`M-e'
     In C mode, `M-a' and `M-e' now move by complete C statements
     (`c-beginning-of-statement' and `c-end-of-statement').

`M-q'
     `M-q' in C mode now runs `c-fill-paragraph', which is designed for
     filling C comments.  (We assume you don't want to fill the actual C
     code in a C program.)

`M-x c-up-conditional'
     In C mode, `c-up-conditional' moves back to the containing
     preprocessor conditional, setting the mark where point was
     previously.

     A prefix argument acts as a repeat count.  With a negative
     argument, this command moves forward to the end of the containing
     preprocessor conditional.  When going backwards, `#elif' acts like
     `#else' followed by `#if'.  When going forwards, `#elif' is
     ignored.

`M-x comment-region'
     The `comment-region' command adds comment delimiters to the lines
     that start in the region, thus commenting them out.  With a
     negative argument, it deletes comment delimiters from the lines in
     the region--this is the inverse of the effect of `comment-region'
     without an argument.

     With a positive argument, `comment-region' adds comment delimiters
     but duplicates the last character of the comment start sequence as
     many times as the argument specifies.  This is a way of calling
     attention to the comment.  In Lisp, you should use an argument of
     at least two, because the indentation convention for single
     semicolon comments does not leave them at the beginning of a line.

`M-x super-apropos'
     This command is like `apropos' except that it searches for a
     regular expression instead of merely a substring.

     If you use a prefix argument (regardless of its value) with
     `apropos' or `super-apropos', they also search documentation
     strings for matches as well as symbol names.  The prefix argument
     also controls looking up and printing the key bindings of all
     commands.

`M-x diff'
     This new command compares two files, displaying the differences in
     an Emacs buffer.  The options for the `diff' program come from the
     variable `diff-switches', whose value should be a string.

     The buffer of differences has Compilation mode as its major mode,
     so you can use `C-x `' to visit successive changed locations in
     the two source files, or you can move to a particular hunk of
     changes and type `C-c C-c' to move to the corresponding source.
     You can also use the other special commands of Compilation mode:
     SPC and DEL for scrolling, and `M-p' and `M-n' for cursor motion.

`M-x diff-backup'
     The command `diff-backup' compares a specified file with its most
     recent backup.  If you specify the name of a backup file,
     `diff-backup' compares it with the source file that it is a backup
     of.


File: emacs,  Node: Search Changes,  Next: Filling Changes,  Prev: New Commands,  Up: Version 19

Changes in Incremental Search
=============================

   The most important change in incremental search is that RET now
terminates a search, and ESC does not.  The other changes are useful,
but not vital to know about.

   * The character to terminate an incremental search is now RET.  This
     is for compatibility with the way most other arguments are read.

     To search for a newline in an incremental search, type LFD (also
     known as `C-j').

     (This change is somewhat of an experiment; it might be taken back
     by the time Emacs 19 is really released.)

   * Incremental search now maintains a ring of previous search
     strings.  Use `M-p' and `M-n' to move through the ring to pick a
     search string to reuse.  These commands leave the selected search
     ring element in the minibuffer, where you can edit it.  Type RET
     to finish editing and search for the chosen string.

   * When there is an upper-case letter in the search string, then the
     search is case sensitive.

   * Incremental search is now implemented as a major mode.  When you
     type `C-s', it switches temporarily to a different keymap which
     defines each key to do what it ought to do for incremental search.
      This has next to no effect on the user-visible behavior of
     searching, but makes it easier to customize that behavior.


File: emacs,  Node: Filling Changes,  Next: TeX Mode Changes,  Prev: Search Changes,  Up: Version 19

Changes in Fill Commands
========================

   * `fill-individual-paragraphs' now has two modes.  Its default mode
     is that any change in indentation starts a new paragraph.  The
     alternate mode is that only separator lines separate paragraphs;
     this can handle paragraphs with extra indentation on the first
     line.  To select the alternate mode, set
     `fill-individual-varying-indent' to a non-`nil' value.

   * Filling is now partially controlled by a new minor mode, Adaptive
     Fill mode.  When this mode is enabled (and it is enabled by
     default), if you use `fill-region-as-paragraph' on an indented
     paragraph and you don't have a fill prefix, it uses the
     indentation of the second line of the paragraph as the fill prefix.

     Adaptive Fill mode doesn't have much effect on `M-q' in most major
     modes, because an indented line will probably count as a paragraph
     starter and thus each line of an indented paragraph will be
     considered a paragraph of its own.

   * `M-q' in C mode now runs `c-fill-paragraph', which is designed for
     filling C comments.  (We assume you don't want to fill the actual C
     code in a C program.)