In this chapter we describe the commands that are especially useful for the times when you catch a mistake in your text just after you have made it, or change your mind while composing text on the fly.
The most fundamental command for correcting erroneous editing is the
undo command, C-x u or C-_. This command undoes a single
command (usually), a part of a command (in the case of
query-replace), or several consecutive self-inserting characters.
Consecutive repetitions of C-_ or C-x u undo earlier and
earlier changes, back to the limit of the undo information available.
See section Undoing Changes, for for more information.
delete-backward-char).
backward-kill-word).
backward-kill-sentence).
The DEL character (delete-backward-char) is the most
important correction command. It deletes the character before point.
When DEL follows a self-inserting character command, you can think
of it as canceling that command. However, avoid the mistake of thinking
of DEL as a general way to cancel a command!
When your mistake is longer than a couple of characters, it might be more convenient to use M-DEL or C-x DEL. M-DEL kills back to the start of the last word, and C-x DEL kills back to the start of the last sentence. C-x DEL is particularly useful when you change your mind about the phrasing of the text you are writing. M-DEL and C-x DEL save the killed text for C-y and M-y to retrieve. See section Yanking.
M-DEL is often useful even when you have typed only a few characters wrong, if you know you are confused in your typing and aren't sure exactly what you typed. At such a time, you cannot correct with DEL except by looking at the screen to see what you did. Often it requires less thought to kill the whole word and start again.
transpose-chars).
transpose-words).
transpose-sexps).
transpose-lines).
The common error of transposing two characters can be fixed, when they
are adjacent, with the C-t command (transpose-chars). Normally,
C-t transposes the two characters on either side of point. When
given at the end of a line, rather than transposing the last character of
the line with the newline, which would be useless, C-t transposes the
last two characters on the line. So, if you catch your transposition error
right away, you can fix it with just a C-t. If you don't catch it so
fast, you must move the cursor back to between the two transposed
characters. If you transposed a space with the last character of the word
before it, the word motion commands are a good way of getting there.
Otherwise, a reverse search (C-r) is often the best way.
See section Searching and Replacement.
M-t (transpose-words) transposes the word before point
with the word after point. It moves point forward over a word, dragging
the word preceding or containing point forward as well. The punctuation
characters between the words do not move. For example, `FOO, BAR'
transposes into `BAR, FOO' rather than `BAR FOO,'.
C-M-t (transpose-sexps) is a similar command for transposing
two expressions (see section Lists and Sexps), and C-x C-t (transpose-lines)
exchanges lines. They work like M-t except in determining the
division of the text into syntactic units.
A numeric argument to a transpose command serves as a repeat count: it tells the transpose command to move the character (word, sexp, line) before or containing point across several other characters (words, sexps, lines). For example, C-u 3 C-t moves the character before point forward across three other characters. It would change `f-!-oobar' into `oobf-!-ar'. This is equivalent to repeating C-t three times. C-u - 4 M-t moves the word before point backward across four words. C-u - C-M-t would cancel the effect of plain C-M-t.
A numeric argument of zero is assigned a special meaning (because otherwise a command with a repeat count of zero would do nothing): to transpose the character (word, sexp, line) ending after point with the one ending after the mark.
A very common error is to type words in the wrong case. Because of this, the word case-conversion commands M-l, M-u and M-c have a special feature when used with a negative argument: they do not move the cursor. As soon as you see you have mistyped the last word, you can simply case-convert it and go on typing. See section Case Conversion Commands.
This section describes the commands to check the spelling of a single word or of a portion of a buffer. These commands work with the spelling checker program Ispell, which is not part of Emacs.
ispell-word).
To check the spelling of the word around or next to point, and
optionally correct it as well, use the command M-$
(ispell-word). If the word is not correct, the command offers
you various alternatives for what to do about it.
To check the entire current buffer, use M-x ispell-buffer. Use M-x ispell-region to check just the current region. To check spelling in an email message you are writing, use M-x ispell-message; that checks the whole buffer, but does not check material that is indented or appears to be cited from other messages.
Each time these commands encounter an incorrect word, they ask you what to do. It displays a list of alternatives, usually including several "near-misses"---words that are close to the word being checked. Then you must type a character. Here are the valid responses:
query-replace so you
can replace it elsewhere in the buffer if you wish.
The command ispell-complete-word, which is bound to the key
M-TAB in Text mode and related modes, shows a list of
completions based on spelling correction. Insert the beginning of a
word, and then type M-TAB; the command displays a completion
list window. To choose one of the completions listed, click
Mouse-2 on it, or move the cursor there in the completions window
and type RET. See section Text Mode.
Once started, the Ispell subprocess continues to run (waiting for something to do), so that subsequent spell checking commands complete more quickly. If you want to get rid of the Ispell process, use M-x ispell-kill-ispell. This is not usually necessary, since the process uses no time except when you do spelling correction.
Ispell uses two dictionaries: the standard dictionary and your private
dictionary. The variable ispell-dictionary specifies the file
name of the standard dictionary to use. A value of nil says to
use the default dictionary. The command M-x
ispell-change-dictionary sets this variable and then restarts the
Ispell subprocess, so that it will use a different dictionary.