@c This is part of the Emacs manual.
@c Copyright (C) 1993, 1994 Free Software Foundation, Inc.
@c See file emacs.texi for copying conditions.

@node Antinews, MS-DOS, Command Arguments, Top
@appendix Emacs 18 Antinews

For those users who live backwards in time, here is information about
downgrading to Emacs version 18.  We hope you will enjoy the greater
simplicity that results from the absence of many Emacs 19 features.

@heading Packages Removed

To reduce the size of the distribution, we have eliminated numerous
packages including GNUS, VC (version control), Hexl (for editing
binary files), Edebug, Emerge, Mpuz, Spook, and Gomoku.

Major modes removed in Emacs 18 include C++ mode, Awk mode, Icon mode,
Asm mode, Makefile mode, Perl mode and SGML mode.

The function @code{enable-flow-control} does not exist; see the file
@file{PROBLEMS} in the Emacs distribution for directions for coping
with flow control.

The Calendar feature provided is a very simple one.  All it can do is
display three months, by default centered around the current month.
If you give it a numeric argument, that specifies the number of months
forward or back.

@heading Fundamental Changes

Auto save and garbage collection happen only while you are typing,
never while you are idle.  This is to make them more like affectionate
pets.  Think of them as cats that like to sit on your terminal only
when you are working there.

Transient Mark mode and Line Number mode are absent in Emacs 18.  If
you are an Emacs user, you are smart enough to keep track of the mark
in your head, and you don't need line numbers because you can search
for precisely the text you want.

There are no menu bars or scroll bars; no faces, text properties or
overlays.  You can't use @kbd{Mouse-2} to select files or objects
referred to in the buffer.

There are no minibuffer history commands.

There is only one frame, so the Emacs 19 @kbd{C-x 5} command series is
meaningless.  Instead, @kbd{C-x 5} in Emacs 18 splits the selected window
horizontally (like @kbd{C-x 3} in Emacs 19).

Another simplification in Emacs 18 is that all input events are
characters.  Function keys and arrow keys are represented as sequences
of characters; the terminal-specific Emacs Lisp file for your terminal
is responsible for defining them.  Mouse buttons are defined by a
special keymap, @code{mouse-map}.  See the file @file{x-mouse.el} for
how to bind mouse clicks.

There is no support for European character sets such as ISO Latin-1.
Character codes 128 and above always display using @samp{\@var{nnn}}
notation.  For codes 0 through 31, you can choose between
@samp{\@var{nnn}} and @samp{^@var{c}} by setting the variable
@code{ctl-arrow}; but that is the only thing you can specify about how
character codes should display.

You can't refer to files on other machines using special ``magic''
file names.  Instead, you must use the @code{ftp} library with
commands such as @kbd{M-x ftp-find-file} and @kbd{M-x
ftp-write-file}.  Since automatic uncompression also uses magic file
names, that too is gone.

The character for terminating an incremental search is now @key{ESC},
not @key{RET} as in Emacs 19.  If you type @key{RET}, that searches
for a newline; thus, you can insert a newline in the search string
just as you would insert it in the text.

@heading Key Binding Changes

The key for @code{backward-paragraph} is now @kbd{M-[}.  The key for
@code{forward-paragraph} is now @kbd{M-]}.

The command @code{repeat-complex-command} is now on @kbd{C-x @key{ESC}}.

The register commands have different key bindings:

@table @kbd
@item C-x /
@code{point-to-register}
@item C-x j
@code{jump-to-register}
@item C-x x
@code{copy-to-register}
@item C-x g
@code{insert-register}
@item C-x r
@code{copy-rectangle-to-register}
@end table

The narrowing commands have also been moved:

@table @kbd
@item C-x n
@code{narrow-to-region}
@item C-x p
@code{narrow-to-page}
@item C-x w
@code{widen}
@end table

And the abbrev commands as well:

@table @kbd
@item C-x C-a
@code{add-mode-abbrev}
@item C-x +
@code{add-global-abbrev}
@item C-x C-h
@code{inverse-add-mode-abbrev}
@item C-x -
@code{inverse-add-global-abbrev}
@item C-x `
@code{expand-abbrev}
@end table

There are no key bindings for the rectangle commands.

@kbd{C-x a} now runs the command @code{append-to-buffer}.

The key bindings @kbd{C-x 4 r} and @kbd{C-x 4 C-o} do not exist.

The help commands @kbd{C-h C-f}, @kbd{C-h C-k} and @kbd{C-h p}
do not exist in Emacs 18.

The command @kbd{C-M-l} (@code{reposition-window}) is absent.
Likewise @kbd{C-M-r} (@code{isearch-backward-regexp}).

The ``two column'' commands starting with @kbd{C-x 6} don't exist in
Emacs 18.

The @TeX{} mode bindings of @kbd{C-c @{} and @kbd{C-c @}} have been
moved to @kbd{M-@{} and @kbd{M-@}}.  (These commands are
@code{up-list} and @code{tex-insert-braces}; they are the @TeX{}
equivalents of @kbd{M-(} and @kbd{M-)}.)

@heading Incremental Search Changes

As mentioned above, the character for terminating an incremental
search is now @key{ESC}, not @key{RET} as in Emacs 19.  If you type
@key{RET}, that searches for a newline; thus, you can insert a newline
in the search string just as you would insert it in the text.

There is no ring of previous search strings in Emacs 18.  You can reuse
the most recent search string, but that's all.

If @code{case-fold-search} is non-@code{nil}, then incremental
search is @emph{always} case-insensitive.  Typing an upper-case letter
in the search string has no effect on this.

Spaces in the incremental search string match only spaces.

The meanings of the special search characters are no longer controlled
by a keymap.  Instead, particular variables named @code{search-@dots{}-char}
specify the character that should have a particular function.
For example, @kbd{C-s} repeats the search because the value of
@code{search-repeat-char} is @code{?\C-s}.

@heading Editing Command Changes

@kbd{C-n} (@code{next-line}) does not check the variable
@code{next-line-add-newlines}.

The sexp commands such as @kbd{C-M-f} no longer know anything about
comments, in modes such as Lisp mode where the end of a comment is the
end of the line.  They treat the text inside a comment as if it were
actual code.  If comments containing unbalanced parentheses cause
trouble, you can use the commands @kbd{C-M-n} and @kbd{C-M-p}, which
do ignore comments.

You can't store file names in registers, and there are no frame
configurations at all.  The command @kbd{M-x string-rectangle} does not
exist either.

The undo command in Emacs 18 is not careful about where to leave point
when you undo a deletion.  It ends up at one end or the other of the
text just undeleted.  You must be on the lookout for this, and move
point appropriately.

Kill commands do nothing useful in read-only buffers.  They just beep.

@kbd{M-z @var{c}} in Emacs 18 kills up to but not including the first
occurrence of @var{c}.  If @var{c} does not occur in the buffer after
point, @kbd{M-z} kills the whole rest of the buffer.

The function @code{erase-buffer} is not a command in Emacs 18.  You
can call it from a Lisp program, but not interactively.  The
motivation for this is to protect you from accidentally deleting (not
killing) the entire text of a buffer that you want to keep.  With
subsequent changes in even earlier Emacs versions (such as version
18.54), you might be unable to undo the @code{erase-buffer}.

@kbd{M-x fill-nonuniform-paragraphs} and Adaptive Fill mode do not exist.

@heading Other Brief Notes

The mode line displays @samp{%%} for all read-only buffers, whether
modified or not.

The command @code{resize-minibuffer-mode} has been removed.  If you want
to change the size of the minibuffer, do it by hand.

Outline mode exists only as a major mode, not as a minor mode.

@kbd{M-!} (@code{shell-command}) always runs the command synchronously,
even if the command ends with @samp{&}.

Emacs 18 has no special mode for change log files.  It is a good idea
to use Indented Text mode, and specify 8 as the value of the variable
@code{left-margin}.

The command @kbd{M-x comment-region} does not exist.
The command @kbd{M-x super-apropos} does not exist.

@kbd{C-x q} (@code{kbd-macro-query}) now uses @kbd{C-d} to terminate
all iterations of the keyboard macro, rather than @key{ESC}.

The @kbd{M-x setenv} command is missing in Emacs 18.

@kbd{M-$} now uses the Unix spell program instead of the GNU program
Ispell.  If the word around point is a misspelling, it asks you for a
replacement.

To check spelling of larger units of text, use @kbd{M-x spell-region}
or @kbd{M-x spell-buffer}.  These commands check all words in the specified
piece of text.  For each word that is not correct, they ask you to
specify a replacement, and then replace each occurrence.

@kbd{M-x gdb} still exists in Emacs 18.  @kbd{M-x dbx} exists, but is
somewhat different (use @kbd{C-h m} to find the details).  @kbd{M-x
sdb} does not exist at all, but who wants to use SDB?

In Buffer Menu mode, the commands @kbd{%} and @kbd{C-o} don't work in
Emacs 18.  The @kbd{v} command has been eliminated and merged with the
@kbd{q} command, which now exits the buffer menu, displaying all the
buffers that you have marked.

The View commands (such as @kbd{M-x view-buffer} and @kbd{M-x
view-file}) now use recursive edits.  When you exit viewing, the
recursive edit returns to its caller.

Emacs 18, like most programs, interprets command line options only when
it is started--not later on.

The variable to control whether files can set local variables is called
@code{inhibit-local-variables}.  A non-@code{nil} value means ask the
user before obeying any local variables lists.

The user option for controlling use of the @code{eval} local variable
is now called @code{inhibit-local-eval}.  A non-@code{nil} value means
to ask the user before obeying any @code{eval} local variable.

@heading File Handling Changes

As mentioned above, you can't refer to files on other machines using
special ``magic'' file names.  Instead, you must use the @code{ftp}
library with commands such as @kbd{M-x ftp-find-file} and @kbd{M-x
ftp-write-file}.

When you run @kbd{M-x revert-buffer} with no numeric argument, if the
buffer has an auto save file more recent that the visited file,
@code{revert-buffer} asks whether to revert from the auto save file
instead.

When @kbd{C-x s} (@code{save-some-buffers}) offers to save each buffer,
you have only two choices: save it, or don't save it.

@kbd{M-x recover-file} turns off Auto Save mode in the current buffer.
To turn it on again, use @kbd{M-x auto-save-mode}.

The command @kbd{M-x rename-uniquely} does not exist; instead, use
@kbd{M-x rename-buffer} and try various names until you find one that
isn't in use.  Completion can make this easier.

The directory name abbreviation feature is gone in Emacs 18.

Emacs 18 has no idea of file truenames, and does not try to detect
when you visit a file via a symbolic link.  You should check manually
when you visit a file, so as to edit it in the directory where it is
actually stored.  This way you can make sure that backup files and
change log entries go in the proper directory.

@kbd{M-x compare-windows} ignores any numeric argument and always
considers case and whitespace differences significant.  As for the
other ways of comparing files, @kbd{M-x diff} and @kbd{M-x
diff-backup}, they don't exist at all.

@heading Mail Changes

@samp{%} is now a word-component character in Mail mode.  This is to
be compatible with Text mode.

The variable @code{mail-signature} is not meaningful; if you wish to
insert your signature in a mail message, you must type @kbd{C-c C-w}.

Mail aliases expand only when you send the message---never when you
type them in.

Rmail now gets new mail into your primary mail file from @file{~/mbox}
as well as from your system inbox file.  This is handy if you
occasionally check your newest mail with the @code{mail} program;
whatever you have looked at and saved with @code{mail} will be brought
into Rmail the next time you run Rmail.

The @kbd{e} command is now ``expunge'', just like @kbd{x}.  To edit
the current message, type @kbd{w}, which works in Emacs 19 as well.
If you type @kbd{e} meaning to edit, and it expunges instead---well,
you shouldn't have deleted those messages if you still wanted them.

The Rmail summary buffer is now much simpler.  Only a few special
commands are available there: @kbd{n}, @kbd{p}, and @kbd{j} for motion,
@kbd{d} and @kbd{u} for deletion, and @key{SPC} and @key{DEL} for
scrolling the message.  To do anything else, you must go to the Rmail
buffer.  Also, changes in the Rmail buffer don't update the summary;
to do that, you must make a new summary.

The Rmail command @code{rmail-resend} (accessible via @kbd{f} with a
numeric argument in Emacs 19) does not exist in Emacs 18.  Neither does
@code{rmail-retry-failure} (@kbd{M-m} in Emacs 19).

The Rmail sorting features have been removed, so you can be sure the
order you see is the order that the messages arrived.

The @kbd{<} and @kbd{b} commands have been removed in Emacs 18.
Likewise @kbd{C-M-t} (@code{rmail-summarize-by-topic}) and 
@kbd{M-x unrmail}.  Rmail in Emacs 18 is so good, that we can't
imagine anyone who has tried it would ever wish to use another mail
reader.

You must use the @kbd{o} command for output to a Rmail file, and the
@kbd{C-o} for output to a file in system mailbox format.  The default
output file for @kbd{o} is now always the last file that you used with
@kbd{o}.  The variable @code{rmail-output-file-alist} has no special
meaning.

Emacs 18 Rmail does not know anything about Content Length fields in
messages.

@heading C Mode Changes

In C mode, the keys @kbd{M-a} and @kbd{M-e} now have their usual meanings:
motion by sentences.  This is useful while editing the comments in a C
program, but not useful for editing code.  We hope this will encourage
you to write lots of comments.

The commands @kbd{M-x c-up-conditional} and @kbd{M-x c-backslash-region} have
been removed entirely in Emacs 18.

@heading Compilation Changes

@kbd{M-x compile} now has a much simpler and faster parser for error
messages.  However, it understands fewer different formats for error
messages, and is not as easy to customize.

There is no special mode for compilation buffers.  When you select the
compilation buffer itself, it is just ordinary text.

Speaking of selecting the compilation buffer, you do need to do that
from time to time to see whether the compilation has finished, because
Emacs 18 does not display @samp{Compiling} in the mode line to tell
you the compilation is still going.

@heading Shell Mode Changes

Shell mode in Emacs 18 does nothing special for the keys @key{TAB},
@kbd{M-?}, @kbd{C-d}.  The commands @kbd{M-x dirs} and @kbd{M-x
send-invisible} are also gone.

The history commands @kbd{M-p} and so on are not available either;
instead, use @kbd{C-c C-y} (@code{copy-last-shell-input}).  This
copies the previous bunch of shell input, and inserts it into the
buffer before point.  No final newline is inserted, and the input
copied is not resubmitted until you type @key{RET}.

Use @kbd{C-c C-d} to send an ``end of file'' to the shell process.

@heading Dired Changes

For simplicity, Dired in Emacs 18 supports just one kind of mark: the
deletion flag, @samp{D}.  The Emacs 19 Dired commands for flagging
files do work in Emacs 18, but all the other mark-related commands do
not.

The Dired subdirectory commands don't exist in Emacs 18.  A Dired buffer
can contain only one directory.  In particular, this means that 
the variable @code{dired-listing-switches} must not contain the @samp{R}
option.  (The @samp{F} option is also not allowed.)

The commands for using @code{find} with Dired have been removed for
simplicity, also.
 
Emacs 18 Dired provides the following commands for manipulating files
immediately, and no others.  All of these commands apply to the file
listed on the current line.

@table @kbd
@item c
Copies the file described on the current line.  You must supply a file name
to copy to, using the minibuffer.
@item f
Visits the file described on the current line.  It is just like typing
@kbd{C-x C-f} and supplying that file name.  If the file on this line is a
subdirectory, @kbd{f} actually causes Dired to be invoked on that
subdirectory.
@item G
Change the group of the file described on the current line.
@item M
Change the file mode of the file described on the current line.
@item o
Like @kbd{f}, but uses another window to display the file's buffer.  The
Dired buffer remains visible in the first window.  This is like using
@kbd{C-x 4 C-f} to visit the file.
@item O
Change the owner of the file described on the current line.
(On most systems, you must be a superuser to do this.)
@item r
Renames the file described on the current line.  You must supply a file
name to rename to, using the minibuffer.
@item v
Views the file described on this line using @kbd{M-x view-file}.  Viewing a
file is like visiting it, but is slanted toward moving around in the file
conveniently and does not allow changing the file.
@end table

