L. Commands for Fixing Typos

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 D.4 Undoing Changes, for more information.

L.1 Killing Your Mistakes

DEL

Delete last character (delete-backward-char).

M-DEL

Kill last word (backward-kill-word).

C-x DEL

Kill to beginning of sentence (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 H.8 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.

L.2 Transposing Text

C-t

Transpose two characters (transpose-chars).

M-t

Transpose two words (transpose-words).

C-M-t

Transpose two balanced expressions (transpose-sexps).

C-x C-t

Transpose two lines (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 between the two transposed characters before you type C-t. 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 K. Searching and Replacement.

M-t transposes the word before point with the word after point (transpose-words). 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 U.4.1 Expressions with Balanced Parentheses), and C-x C-t (transpose-lines) exchanges lines. They work like M-t except as regards what units of text they transpose.

A numeric argument to a transpose command serves as a repeat count: it tells the transpose command to move the character (word, expression, line) before or containing point across several other characters (words, expressions, 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, expression, line) ending after point with the one ending after the mark.

L.3 Case Conversion

M-- M-l

Convert last word to lower case. Note Meta-- is Meta-minus.

M-- M-u

Convert last word to all upper case.

M-- M-c

Convert last word to lower case with capital initial.

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 T.6 Case Conversion Commands.

L.4 Checking and Correcting Spelling

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. See section `Overview ispell' in The Ispell Manual.

M-x flyspell-mode

Enable Flyspell mode, which highlights all misspelled words.

M-$

Check and correct spelling of the word at point (ispell-word).

M-TAB

Complete the word before point based on the spelling dictionary (ispell-complete-word).

M-x ispell

Spell-check the active region or the current buffer.

M-x ispell-buffer

Check and correct spelling of each word in the buffer.

M-x ispell-region

Check and correct spelling of each word in the region.

M-x ispell-message

Check and correct spelling of each word in a draft mail message, excluding cited material.

M-x ispell-change-dictionary RET dict RET

Restart the Ispell process, using dict as the dictionary.

M-x ispell-kill-ispell

Kill the Ispell subprocess.

Flyspell mode is a fully-automatic way to check spelling as you edit in Emacs. It operates by checking words as you change or insert them. When it finds a word that it does not recognize, it highlights that word. This does not interfere with your editing, but when you see the highlighted word, you can move to it and fix it. Type M-x flyspell-mode to enable or disable this mode in the current buffer.

When Flyspell mode highlights a word as misspelled, you can click on it with Mouse-2 to display a menu of possible corrections and actions. You can also correct the word by editing it manually in any way you like.

The other Emacs spell-checking features check or look up words when you give an explicit command to do so. Checking all or part of the buffer is useful when you have text that was written outside of this Emacs session and might contain any number of misspellings.

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 command checks the whole buffer, except for material that is indented or appears to be cited from other messages.

The M-x ispell command spell-checks the active region if the Transient Mark mode is on (see section H.2 Transient Mark Mode), otherwise it spell-checks the current buffer.

Each time these commands encounter an incorrect word, they ask you what to do. They display a list of alternatives, usually including several "near-misses"---words that are close to the word being checked. Then you must type a single-character response. Here are the valid responses:

SPC

Skip this word--continue to consider it incorrect, but don't change it here.

r new RET

Replace the word (just this time) with new.

R new RET

Replace the word with new, and do a query-replace so you can replace it elsewhere in the buffer if you wish.

digit

Replace the word (just this time) with one of the displayed near-misses. Each near-miss is listed with a digit; type that digit to select it.

a

Accept the incorrect word--treat it as correct, but only in this editing session.

A

Accept the incorrect word--treat it as correct, but only in this editing session and for this buffer.

i

Insert this word in your private dictionary file so that Ispell will consider it correct from now on, even in future sessions.

u

Insert the lower-case version of this word in your private dictionary file.

m

Like i, but you can also specify dictionary completion information.

l word RET

Look in the dictionary for words that match word. These words become the new list of "near-misses"; you can select one of them as the replacement by typing a digit. You can use `*' in word as a wildcard.

C-g

Quit interactive spell checking. You can restart it again afterward with C-u M-$.

X

Same as C-g.

x

Quit interactive spell checking and move point back to where it was when you started spell checking.

q

Quit interactive spell checking and kill the Ispell subprocess.

C-l

Refresh the screen.

C-z

This key has its normal command meaning (suspend Emacs or iconify this frame).

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 T.7 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.

The dictionary used by ispell-complete-word can be customized separately by setting the value of the variable ispell-complete-word-dict.