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.
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 enable-flow-control does not exist; see the 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.
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 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 C-x 5 command series is meaningless. Instead, C-x 5 in Emacs 18 splits the selected window horizontally (like 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, mouse-map. See the 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 `\nnn'
notation. For codes 0 through 31, you can choose between
`\nnn' and `^c' by setting the variable
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 ftp library with
commands such as M-x ftp-find-file and 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 ESC, not RET as in Emacs 19. If you type 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.
The key for backward-paragraph is now M-[. The key for
forward-paragraph is now M-].
The command repeat-complex-command is now on C-x ESC.
The register commands have different key bindings:
point-to-register
jump-to-register
copy-to-register
insert-register
copy-rectangle-to-register
The narrowing commands have also been moved:
narrow-to-region
narrow-to-page
widen
And the abbrev commands as well:
add-mode-abbrev
add-global-abbrev
inverse-add-mode-abbrev
inverse-add-global-abbrev
expand-abbrev
There are no key bindings for the rectangle commands.
C-x a now runs the command append-to-buffer.
The key bindings C-x 4 r and C-x 4 C-o do not exist.
The help commands C-h C-f, C-h C-k and C-h p do not exist in Emacs 18.
The command C-M-l (reposition-window) is absent.
Likewise C-M-r (isearch-backward-regexp).
The "two column" commands starting with C-x 6 don't exist in Emacs 18.
The TeX mode bindings of C-c { and C-c } have been
moved to M-{ and M-}. (These commands are
up-list and tex-insert-braces; they are the TeX
equivalents of M-( and M-).)
As mentioned above, the character for terminating an incremental search is now ESC, not RET as in Emacs 19. If you type 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 case-fold-search is non-nil, then incremental
search is 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 search-...-char
specify the character that should have a particular function.
For example, C-s repeats the search because the value of
search-repeat-char is ?\C-s.
C-n (next-line) does not check the variable
next-line-add-newlines.
The sexp commands such as 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 C-M-n and 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 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.
M-z c in Emacs 18 kills up to but not including the first occurrence of c. If c does not occur in the buffer after point, M-z kills the whole rest of the buffer.
The function 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 erase-buffer.
M-x fill-nonuniform-paragraphs and Adaptive Fill mode do not exist.
The mode line displays `%%' for all read-only buffers, whether modified or not.
The command 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.
M-! (shell-command) always runs the command synchronously,
even if the command ends with `&'.
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
left-margin.
The command M-x comment-region does not exist. The command M-x super-apropos does not exist.
C-x q (kbd-macro-query) now uses C-d to terminate
all iterations of the keyboard macro, rather than ESC.
The M-x setenv command is missing in Emacs 18.
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 M-x spell-region or 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.
M-x gdb still exists in Emacs 18. M-x dbx exists, but is somewhat different (use C-h m to find the details). M-x sdb does not exist at all, but who wants to use SDB?
In Buffer Menu mode, the commands % and C-o don't work in Emacs 18. The v command has been eliminated and merged with the q command, which now exits the buffer menu, displaying all the buffers that you have marked.
The View commands (such as M-x view-buffer and 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
inhibit-local-variables. A non-nil value means ask the
user before obeying any local variables lists.
The user option for controlling use of the eval local variable
is now called inhibit-local-eval. A non-nil value means
to ask the user before obeying any eval local variable.
As mentioned above, you can't refer to files on other machines using
special "magic" file names. Instead, you must use the ftp
library with commands such as M-x ftp-find-file and M-x
ftp-write-file.
When you run M-x revert-buffer with no numeric argument, if the
buffer has an auto save file more recent that the visited file,
revert-buffer asks whether to revert from the auto save file
instead.
When C-x s (save-some-buffers) offers to save each buffer,
you have only two choices: save it, or don't save it.
M-x recover-file turns off Auto Save mode in the current buffer. To turn it on again, use M-x auto-save-mode.
The command M-x rename-uniquely does not exist; instead, use 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.
M-x compare-windows ignores any numeric argument and always considers case and whitespace differences significant. As for the other ways of comparing files, M-x diff and M-x diff-backup, they don't exist at all.
`%' is now a word-component character in Mail mode. This is to be compatible with Text mode.
The variable mail-signature is not meaningful; if you wish to
insert your signature in a mail message, you must type 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 `~/mbox'
as well as from your system inbox file. This is handy if you
occasionally check your newest mail with the mail program;
whatever you have looked at and saved with mail will be brought
into Rmail the next time you run Rmail.
The e command is now "expunge", just like x. To edit the current message, type w, which works in Emacs 19 as well. If you type 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: n, p, and j for motion, d and u for deletion, and SPC and 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 rmail-resend (accessible via f with a
numeric argument in Emacs 19) does not exist in Emacs 18. Neither does
rmail-retry-failure (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 < and b commands have been removed in Emacs 18.
Likewise C-M-t (rmail-summarize-by-topic) and
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 o command for output to a Rmail file, and the
C-o for output to a file in system mailbox format. The default
output file for o is now always the last file that you used with
o. The variable rmail-output-file-alist has no special
meaning.
Emacs 18 Rmail does not know anything about Content Length fields in messages.
In C mode, the keys M-a and 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 M-x c-up-conditional and M-x c-backslash-region have been removed entirely in Emacs 18.
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 `Compiling' in the mode line to tell you the compilation is still going.
Shell mode in Emacs 18 does nothing special for the keys TAB, M-?, C-d. The commands M-x dirs and M-x send-invisible are also gone.
The history commands M-p and so on are not available either;
instead, use C-c C-y (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 RET.
Use C-c C-d to send an "end of file" to the shell process.
For simplicity, Dired in Emacs 18 supports just one kind of mark: the deletion flag, `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 dired-listing-switches must not contain the `R'
option. (The `F' option is also not allowed.)
The commands for using 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.