1 @c This is part of the Emacs manual.
2 @c Copyright (C) 1985-1987, 1993-1995, 1997, 2000-2012
3 @c Free Software Foundation, Inc.
4 @c See file emacs.texi for copying conditions.
6 @chapter Basic Editing Commands
9 @findex help-with-tutorial
10 Here we explain the basics of how to enter text, make corrections,
11 and save the text in a file. If this material is new to you, we
12 suggest you first run the Emacs learn-by-doing tutorial, by typing
13 @kbd{C-h t} (@code{help-with-tutorial}).
17 * Inserting Text:: Inserting text by simply typing it.
18 * Moving Point:: Moving the cursor to the place where you want to
20 * Erasing:: Deleting and killing text.
21 * Basic Undo:: Undoing recent changes in the text.
22 * Files: Basic Files. Visiting, creating, and saving files.
23 * Help: Basic Help. Asking what a character does.
24 * Blank Lines:: Making and deleting blank lines.
25 * Continuation Lines:: How Emacs displays lines too wide for the screen.
26 * Position Info:: What line, row, or column is point on?
27 * Arguments:: Numeric arguments for repeating a command N times.
28 * Repeating:: Repeating the previous command quickly.
32 @section Inserting Text
35 @cindex graphic characters
36 You can insert an ordinary @dfn{graphic character} (e.g., @samp{a},
37 @samp{B}, @samp{3}, and @samp{=}) by typing the associated key. This
38 adds the character to the buffer at point. Insertion moves point
39 forward, so that point remains just after the inserted text.
44 To end a line and start a new one, type @key{RET} (@code{newline}).
45 (The @key{RET} key may be labeled @key{Return} or @key{Enter} on your
46 keyboard, but we refer to it as @key{RET} in this manual.) This
47 command inserts a newline character into the buffer. If point is at
48 the end of the line, the effect is to create a new blank line after
49 it; if point is in the middle of a line, the line is split at that
52 As we explain later in this manual, you can change the way Emacs
53 handles text insertion by turning on @dfn{minor modes}. For instance,
54 the minor mode called Auto Fill mode splits lines automatically when
55 they get too long (@pxref{Filling}). The minor mode called Overwrite
56 mode causes inserted characters to replace (overwrite) existing text,
57 instead of shoving it to the right. @xref{Minor Modes}.
62 Only graphic characters can be inserted by typing the associated
63 key; other keys act as editing commands and do not insert themselves.
64 For instance, @kbd{DEL} runs the command @code{delete-backward-char}
65 by default (some modes bind it to a different command); it does not
66 insert a literal @samp{DEL} character (@acronym{ASCII} character code
69 To insert a non-graphic character, or a character that your keyboard
70 does not support, first @dfn{quote} it by typing @kbd{C-q}
71 (@code{quoted-insert}). There are two ways to use @kbd{C-q}:
75 @kbd{C-q} followed by any non-graphic character (even @kbd{C-g})
76 inserts that character. For instance, @kbd{C-q @key{DEL}} inserts a
77 literal @samp{DEL} character.
80 @kbd{C-q} followed by a sequence of octal digits inserts the character
81 with the specified octal character code. You can use any number of
82 octal digits; any non-digit terminates the sequence. If the
83 terminating character is @key{RET}, that @key{RET} serves only to
84 terminate the sequence. Any other non-digit terminates the sequence
85 and then acts as normal input---thus, @kbd{C-q 1 0 1 B} inserts
88 The use of octal sequences is disabled in ordinary non-binary
89 Overwrite mode, to give you a convenient way to insert a digit instead
90 of overwriting with it.
93 @vindex read-quoted-char-radix
95 To use decimal or hexadecimal instead of octal, set the variable
96 @code{read-quoted-char-radix} to 10 or 16. If the radix is 16,
97 the letters @kbd{a} to @kbd{f} serve as part of a character code,
98 just like digits. Case is ignored.
102 @cindex Unicode characters, inserting
103 @cindex insert Unicode character
104 @cindex characters, inserting by name or code-point
105 Alternatively, you can use the command @kbd{C-x 8 @key{RET}}
106 (@code{insert-char}). This prompts for the Unicode name or code-point
107 of a character, using the minibuffer. If you enter a name, the
108 command provides completion (@pxref{Completion}). If you enter a
109 code-point, it should be as a hexadecimal number (the convention for
110 Unicode), or a number with a specified radix, e.g.@: @code{#o23072}
111 (octal); @xref{Integer Basics,,, elisp, The Emacs Lisp Reference
112 Manual}. The command then inserts the corresponding character into
113 the buffer. For example, both of the following insert the infinity
114 sign (Unicode code-point @code{U+221E}):
117 @kbd{C-x 8 @key{RET} infinity @key{RET}}
118 @kbd{C-x 8 @key{RET} 221e @key{RET}}
121 A numeric argument to @kbd{C-q} or @kbd{C-x 8 @key{RET}} specifies
122 how many copies of the character to insert (@pxref{Arguments}).
125 @section Changing the Location of Point
130 @cindex cursor motion
131 @cindex moving the cursor
132 To do more than insert characters, you have to know how to move
133 point (@pxref{Point}). The keyboard commands @kbd{C-f}, @kbd{C-b},
134 @kbd{C-n}, and @kbd{C-p} move point to the right, left, down, and up,
135 respectively. You can also move point using the @dfn{arrow keys}
136 present on most keyboards: @kbd{@key{right}}, @kbd{@key{left}},
137 @kbd{@key{down}}, and @kbd{@key{up}}; however, many Emacs users find
138 that it is slower to use the arrow keys than the control keys, because
139 you need to move your hand to the area of the keyboard where those
142 You can also click the left mouse button to move point to the
143 position clicked. Emacs also provides a variety of additional
144 keyboard commands that move point in more sophisticated ways.
151 Move forward one character (@code{forward-char}).
156 This command (@code{right-char}) behaves like @kbd{C-f}, with one
157 exception: when editing right-to-left scripts such as Arabic, it
158 instead moves @emph{backward} if the current paragraph is a
159 right-to-left paragraph. @xref{Bidirectional Editing}.
163 @findex backward-char
164 Move backward one character (@code{backward-char}).
169 This command (@code{left-char}) behaves like @kbd{C-b}, except it
170 moves @emph{forward} if the current paragraph is right-to-left.
171 @xref{Bidirectional Editing}.
178 Move down one screen line (@code{next-line}). This command attempts
179 to keep the horizontal position unchanged, so if you start in the
180 middle of one line, you move to the middle of the next.
186 @findex previous-line
187 Move up one screen line (@code{previous-line}). This command
188 preserves position within the line, like @kbd{C-n}.
194 @findex move-beginning-of-line
195 Move to the beginning of the line (@code{move-beginning-of-line}).
201 @findex move-end-of-line
202 Move to the end of the line (@code{move-end-of-line}).
207 Move forward one word (@code{forward-word}).
214 This command (@code{right-word}) behaves like @kbd{M-f}, except it
215 moves @emph{backward} by one word if the current paragraph is
216 right-to-left. @xref{Bidirectional Editing}.
220 @findex backward-word
221 Move backward one word (@code{backward-word}).
228 This command (@code{left-word}) behaves like @kbd{M-f}, except it
229 moves @emph{forward} by one word if the current paragraph is
230 right-to-left. @xref{Bidirectional Editing}.
234 @findex move-to-window-line-top-bottom
235 Without moving the text on the screen, reposition point on the left
236 margin of the center-most text line of the window; on subsequent
237 consecutive invocations, move point to the left margin of the top-most
238 line, the bottom-most line, and so forth, in cyclic order
239 (@code{move-to-window-line-top-bottom}).
241 A numeric argument says which screen line to place point on, counting
242 downward from the top of the window (zero means the top line). A
243 negative argument counts lines up from the bottom (@minus{}1 means the
244 bottom line). @xref{Arguments}, for more information on numeric
249 @findex beginning-of-buffer
250 Move to the top of the buffer (@code{beginning-of-buffer}). With
251 numeric argument @var{n}, move to @var{n}/10 of the way from the top.
255 @findex end-of-buffer
256 Move to the end of the buffer (@code{end-of-buffer}).
259 @itemx @key{PageDown}
261 Scroll the display one screen forward, and move point onscreen if
262 necessary (@code{scroll-up-command}). @xref{Scrolling}.
267 Scroll one screen backward, and move point onscreen if necessary
268 (@code{scroll-down-command}). @xref{Scrolling}.
273 Read a number @var{n} and move point to buffer position @var{n}.
274 Position 1 is the beginning of the buffer.
281 Read a number @var{n} and move point to the beginning of line number
282 @var{n} (@code{goto-line}). Line 1 is the beginning of the buffer. If
283 point is on or just after a number in the buffer, that is the default
284 for @var{n}. Just type @key{RET} in the minibuffer to use it. You can
285 also specify @var{n} by giving @kbd{M-g M-g} a numeric prefix argument.
286 @xref{Select Buffer}, for the behavior of @kbd{M-g M-g} when you give it
287 a plain prefix argument.
291 @findex move-to-column
292 Read a number @var{n} and move to column @var{n} in the current line.
293 Column 0 is the leftmost column. If called with a prefix argument,
294 move to the column number specified by the argument's numeric value.
298 @findex set-goal-column
299 Use the current column of point as the @dfn{semipermanent goal column}
300 for @kbd{C-n} and @kbd{C-p} (@code{set-goal-column}). When a
301 semipermanent goal column is in effect, those commands always try to
302 move to this column, or as close as possible to it, after moving
303 vertically. The goal column remains in effect until canceled.
306 Cancel the goal column. Henceforth, @kbd{C-n} and @kbd{C-p} try to
307 preserve the horizontal position, as usual.
310 @vindex line-move-visual
311 When a line of text in the buffer is longer than the width of the
312 window, Emacs usually displays it on two or more @dfn{screen lines}.
313 For convenience, @kbd{C-n} and @kbd{C-p} move point by screen lines,
314 as do the equivalent keys @kbd{@key{down}} and @kbd{@key{up}}. You
315 can force these commands to move according to @dfn{logical lines}
316 (i.e., according to the text lines in the buffer) by setting the
317 variable @code{line-move-visual} to @code{nil}; if a logical line
318 occupies multiple screen lines, the cursor then skips over the
319 additional screen lines. For details, see @ref{Continuation Lines}.
320 @xref{Variables}, for how to set variables such as
321 @code{line-move-visual}.
323 Unlike @kbd{C-n} and @kbd{C-p}, most of the Emacs commands that work
324 on lines work on @emph{logical} lines. For instance, @kbd{C-a}
325 (@code{move-beginning-of-line}) and @kbd{C-e}
326 (@code{move-end-of-line}) respectively move to the beginning and end
327 of the logical line. Whenever we encounter commands that work on
328 screen lines, such as @kbd{C-n} and @kbd{C-p}, we will point these
332 When @code{line-move-visual} is @code{nil}, you can also set the
333 variable @code{track-eol} to a non-@code{nil} value. Then @kbd{C-n}
334 and @kbd{C-p}, when starting at the end of the logical line, move to
335 the end of the next logical line. Normally, @code{track-eol} is
338 @vindex next-line-add-newlines
339 @kbd{C-n} normally stops at the end of the buffer when you use it on
340 the last line in the buffer. However, if you set the variable
341 @code{next-line-add-newlines} to a non-@code{nil} value, @kbd{C-n} on
342 the last line of a buffer creates an additional line at the end and
346 @section Erasing Text
347 @cindex killing characters and lines
348 @cindex deleting characters and lines
349 @cindex erasing characters and lines
353 @itemx @key{Backspace}
354 Delete the character before point, or the region if it is active
355 (@code{delete-backward-char}).
358 Delete the character after point, or the region if it is active
359 (@code{delete-forward-char}).
362 Delete the character after point (@code{delete-char}).
365 Kill to the end of the line (@code{kill-line}).
367 Kill forward to the end of the next word (@code{kill-word}).
369 Kill back to the beginning of the previous word
370 (@code{backward-kill-word}).
373 The @kbd{@key{DEL}} (@code{delete-backward-char}) command removes
374 the character before point, moving the cursor and the characters after
375 it backwards. If point was at the beginning of a line, this deletes
376 the preceding newline, joining this line to the previous one.
378 If, however, the region is active, @kbd{@key{DEL}} instead deletes
379 the text in the region. @xref{Mark}, for a description of the region.
381 On most keyboards, @key{DEL} is labeled @key{Backspace}, but we
382 refer to it as @key{DEL} in this manual. (Do not confuse @key{DEL}
383 with the @key{Delete} key; we will discuss @key{Delete} momentarily.)
384 On some text terminals, Emacs may not recognize the @key{DEL} key
385 properly. @xref{DEL Does Not Delete}, if you encounter this problem.
387 The @key{delete} (@code{delete-forward-char}) command deletes in the
388 ``opposite direction'': it deletes the character after point, i.e. the
389 character under the cursor. If point was at the end of a line, this
390 joins the following line onto this one. Like @kbd{@key{DEL}}, it
391 deletes the text in the region if the region is active (@pxref{Mark}).
393 @kbd{C-d} (@code{delete-char}) deletes the character after point,
394 similar to @key{delete}, but regardless of whether the region is
397 @xref{Deletion}, for more detailed information about the above
400 @kbd{C-k} (@code{kill-line}) erases (kills) a line at a time. If
401 you type @kbd{C-k} at the beginning or middle of a line, it kills all
402 the text up to the end of the line. If you type @kbd{C-k} at the end
403 of a line, it joins that line with the following line.
405 @xref{Killing}, for more information about @kbd{C-k} and related
409 @section Undoing Changes
413 Undo one entry of the undo records---usually, one command worth
421 Emacs records a list of changes made in the buffer text, so you can
422 undo recent changes. This is done using the @code{undo} command,
423 which is bound to @kbd{C-/} (as well as @kbd{C-x u} and @kbd{C-_}).
424 Normally, this command undoes the last change, moving point back to
425 where it was before the change. The undo command applies only to
426 changes in the buffer; you can't use it to undo cursor motion.
428 Although each editing command usually makes a separate entry in the
429 undo records, very simple commands may be grouped together.
430 Sometimes, an entry may cover just part of a complex command.
432 If you repeat @kbd{C-/} (or its aliases), each repetition undoes
433 another, earlier change, back to the limit of the undo information
434 available. If all recorded changes have already been undone, the undo
435 command displays an error message and does nothing.
437 To learn more about the @code{undo} command, see @ref{Undo}.
442 Text that you insert in an Emacs buffer lasts only as long as the
443 Emacs session. To keep any text permanently, you must put it in a
446 Suppose there is a file named @file{test.emacs} in your home
447 directory. To begin editing this file in Emacs, type
450 C-x C-f test.emacs @key{RET}
454 Here the file name is given as an @dfn{argument} to the command @kbd{C-x
455 C-f} (@code{find-file}). That command uses the @dfn{minibuffer} to
456 read the argument, and you type @key{RET} to terminate the argument
457 (@pxref{Minibuffer}).
459 Emacs obeys this command by @dfn{visiting} the file: it creates a
460 buffer, copies the contents of the file into the buffer, and then
461 displays the buffer for editing. If you alter the text, you can
462 @dfn{save} the new text in the file by typing @kbd{C-x C-s}
463 (@code{save-buffer}). This copies the altered buffer contents back
464 into the file @file{test.emacs}, making them permanent. Until you
465 save, the changed text exists only inside Emacs, and the file
466 @file{test.emacs} is unaltered.
468 To create a file, just visit it with @kbd{C-x C-f} as if it already
469 existed. This creates an empty buffer, in which you can insert the
470 text you want to put in the file. Emacs actually creates the file the
471 first time you save this buffer with @kbd{C-x C-s}.
473 To learn more about using files in Emacs, see @ref{Files}.
478 @cindex getting help with keys
479 If you forget what a key does, you can find out by typing @kbd{C-h
480 k} (@code{describe-key}), followed by the key of interest; for
481 example, @kbd{C-h k C-n} tells you what @kbd{C-n} does.
483 The prefix key @kbd{C-h} stands for ``help''. The key @key{F1}
484 serves as an alias for @kbd{C-h}. Apart from @kbd{C-h k}, there are
485 many other help commands providing different kinds of help.
487 @xref{Help}, for details.
492 @cindex inserting blank lines
493 @cindex deleting blank lines
494 Here are special commands and techniques for inserting and deleting
499 Insert a blank line after the cursor (@code{open-line}).
501 Delete all but one of many consecutive blank lines
502 (@code{delete-blank-lines}).
509 @findex delete-blank-lines
510 We have seen how @kbd{@key{RET}} (@code{newline}) starts a new line
511 of text. However, it may be easier to see what you are doing if you
512 first make a blank line and then insert the desired text into it.
513 This is easy to do using the key @kbd{C-o} (@code{open-line}), which
514 inserts a newline after point but leaves point in front of the
515 newline. After @kbd{C-o}, type the text for the new line.
517 You can make several blank lines by typing @kbd{C-o} several times, or
518 by giving it a numeric argument specifying how many blank lines to make.
519 @xref{Arguments}, for how. If you have a fill prefix, the @kbd{C-o}
520 command inserts the fill prefix on the new line, if typed at the
521 beginning of a line. @xref{Fill Prefix}.
523 The easy way to get rid of extra blank lines is with the command
524 @kbd{C-x C-o} (@code{delete-blank-lines}). If point lies within a run
525 of several blank lines, @kbd{C-x C-o} deletes all but one of them. If
526 point is on a single blank line, @kbd{C-x C-o} deletes it. If point
527 is on a nonblank line, @kbd{C-x C-o} deletes all following blank
528 lines, if any exists.
530 @node Continuation Lines
531 @section Continuation Lines
533 @cindex continuation line
535 @cindex line wrapping
536 @cindex fringes, and continuation lines
537 Sometimes, a line of text in the buffer---a @dfn{logical line}---is
538 too long to fit in the window, and Emacs displays it as two or more
539 @dfn{screen lines}. This is called @dfn{line wrapping} or
540 @dfn{continuation}, and the long logical line is called a
541 @dfn{continued line}. On a graphical display, Emacs indicates line
542 wrapping with small bent arrows in the left and right window fringes.
543 On a text terminal, Emacs indicates line wrapping by displaying a
544 @samp{\} character at the right margin.
546 Most commands that act on lines act on logical lines, not screen
547 lines. For instance, @kbd{C-k} kills a logical line. As described
548 earlier, @kbd{C-n} (@code{next-line}) and @kbd{C-p}
549 (@code{previous-line}) are special exceptions: they move point down
550 and up, respectively, by one screen line (@pxref{Moving Point}).
553 @cindex line truncation, and fringes
554 Emacs can optionally @dfn{truncate} long logical lines instead of
555 continuing them. This means that every logical line occupies a single
556 screen line; if it is longer than the width of the window, the rest of
557 the line is not displayed. On a graphical display, a truncated line
558 is indicated by a small straight arrow in the right fringe; on a text
559 terminal, it is indicated by a @samp{$} character in the right margin.
560 @xref{Line Truncation}.
562 By default, continued lines are wrapped at the right window edge.
563 Since the wrapping may occur in the middle of a word, continued lines
564 can be difficult to read. The usual solution is to break your lines
565 before they get too long, by inserting newlines. If you prefer, you
566 can make Emacs insert a newline automatically when a line gets too
567 long, by using Auto Fill mode. @xref{Filling}.
570 Sometimes, you may need to edit files containing many long logical
571 lines, and it may not be practical to break them all up by adding
572 newlines. In that case, you can use Visual Line mode, which enables
573 @dfn{word wrapping}: instead of wrapping long lines exactly at the
574 right window edge, Emacs wraps them at the word boundaries (i.e.,
575 space or tab characters) nearest to the right window edge. Visual
576 Line mode also redefines editing commands such as @code{C-a},
577 @code{C-n}, and @code{C-k} to operate on screen lines rather than
578 logical lines. @xref{Visual Line Mode}.
581 @section Cursor Position Information
583 Here are commands to get information about the size and position of
584 parts of the buffer, and to count words and lines.
588 Display the line number of point.
589 @item M-x line-number-mode
590 @itemx M-x column-number-mode
591 Toggle automatic display of the current line number or column number.
592 @xref{Optional Mode Line}.
595 Display the number of lines, words, and characters that are present in
596 the region (@code{count-words-region}). @xref{Mark}, for information
599 @item M-x count-words
600 Display the number of lines, words, and characters that are present in
601 the buffer. If the region is active (@pxref{Mark}), display the
602 numbers for the region instead.
605 Display the character code of character after point, character position of
606 point, and column of point (@code{what-cursor-position}).
607 @item M-x hl-line-mode
608 Enable or disable highlighting of the current line. @xref{Cursor
610 @item M-x size-indication-mode
611 Toggle automatic display of the size of the buffer.
612 @xref{Optional Mode Line}.
616 @cindex line number commands
617 @cindex location of point
618 @cindex cursor location
619 @cindex point location
620 @kbd{M-x what-line} displays the current line number in the echo
621 area. This command is usually redundant, because the current line
622 number is shown in the mode line (@pxref{Mode Line}). However, if you
623 narrow the buffer, the mode line shows the line number relative to
624 the accessible portion (@pxref{Narrowing}). By contrast,
625 @code{what-line} displays both the line number relative to the
626 narrowed region and the line number relative to the whole buffer.
629 @findex count-words-region
630 @kbd{M-=} (@code{count-words-region}) displays a message reporting
631 the number of lines, words, and characters in the region
632 (@pxref{Mark}, for an explanation of the region). With a prefix
633 argument, @kbd{C-u M-=}, the command displays a count for the entire
637 The command @kbd{M-x count-words} does the same job, but with a
638 different calling convention. It displays a count for the region if
639 the region is active, and for the buffer otherwise.
642 @findex what-cursor-position
643 The command @kbd{C-x =} (@code{what-cursor-position}) shows
644 information about the current cursor position and the buffer contents
645 at that position. It displays a line in the echo area that looks like
649 Char: c (99, #o143, #x63) point=28062 of 36168 (78%) column=53
652 After @samp{Char:}, this shows the character in the buffer at point.
653 The text inside the parenthesis shows the corresponding decimal, octal
654 and hex character codes; for more information about how @kbd{C-x =}
655 displays character information, see @ref{International Chars}. After
656 @samp{point=} is the position of point as a character count (the first
657 character in the buffer is position 1, the second character is
658 position 2, and so on). The number after that is the total number of
659 characters in the buffer, and the number in parenthesis expresses the
660 position as a percentage of the total. After @samp{column=} is the
661 horizontal position of point, in columns counting from the left edge
664 If the buffer has been narrowed, making some of the text at the
665 beginning and the end temporarily inaccessible, @kbd{C-x =} displays
666 additional text describing the currently accessible range. For
667 example, it might display this:
670 Char: C (67, #o103, #x43) point=252 of 889 (28%) <231-599> column=0
674 where the two extra numbers give the smallest and largest character
675 position that point is allowed to assume. The characters between
676 those two positions are the accessible ones. @xref{Narrowing}.
679 @section Numeric Arguments
680 @cindex numeric arguments
681 @cindex prefix arguments
682 @cindex arguments to commands
684 In the terminology of mathematics and computing, @dfn{argument}
685 means ``data provided to a function or operation''. You can give any
686 Emacs command a @dfn{numeric argument} (also called a @dfn{prefix
687 argument}). Some commands interpret the argument as a repetition
688 count. For example, giving @kbd{C-f} an argument of ten causes it to
689 move point forward by ten characters instead of one. With these
690 commands, no argument is equivalent to an argument of one, and
691 negative arguments cause them to move or act in the opposite
696 @findex digit-argument
697 @findex negative-argument
698 The easiest way to specify a numeric argument is to type a digit
699 and/or a minus sign while holding down the @key{META} key. For
707 moves down five lines. The keys @kbd{M-1}, @kbd{M-2}, and so on, as
708 well as @kbd{M--}, are bound to commands (@code{digit-argument} and
709 @code{negative-argument}) that set up an argument for the next
710 command. @kbd{Meta--} without digits normally means @minus{}1.
712 If you enter more than one digit, you need not hold down the
713 @key{META} key for the second and subsequent digits. Thus, to move
714 down fifty lines, type
721 Note that this @emph{does not} insert five copies of @samp{0} and move
722 down one line, as you might expect---the @samp{0} is treated as part
723 of the prefix argument.
725 (What if you do want to insert five copies of @samp{0}? Type @kbd{M-5
726 C-u 0}. Here, @kbd{C-u} ``terminates'' the prefix argument, so that
727 the next keystroke begins the command that you want to execute. Note
728 that this meaning of @kbd{C-u} applies only to this case. For the
729 usual role of @kbd{C-u}, see below.)
732 @findex universal-argument
733 Instead of typing @kbd{M-1}, @kbd{M-2}, and so on, another way to
734 specify a numeric argument is to type @kbd{C-u}
735 (@code{universal-argument}) followed by some digits, or (for a
736 negative argument) a minus sign followed by digits. A minus sign
737 without digits normally means @minus{}1.
739 @kbd{C-u} alone has the special meaning of ``four times'': it
740 multiplies the argument for the next command by four. @kbd{C-u C-u}
741 multiplies it by sixteen. Thus, @kbd{C-u C-u C-f} moves forward
742 sixteen characters. Other useful combinations are @kbd{C-u C-n},
743 @kbd{C-u C-u C-n} (move down a good fraction of a screen), @kbd{C-u
744 C-u C-o} (make ``a lot'' of blank lines), and @kbd{C-u C-k} (kill four
747 You can use a numeric argument before a self-inserting character to
748 insert multiple copies of it. This is straightforward when the
749 character is not a digit; for example, @kbd{C-u 6 4 a} inserts 64
750 copies of the character @samp{a}. But this does not work for
751 inserting digits; @kbd{C-u 6 4 1} specifies an argument of 641. You
752 can separate the argument from the digit to insert with another
753 @kbd{C-u}; for example, @kbd{C-u 6 4 C-u 1} does insert 64 copies of
754 the character @samp{1}.
756 Some commands care whether there is an argument, but ignore its
757 value. For example, the command @kbd{M-q} (@code{fill-paragraph})
758 fills text; with an argument, it justifies the text as well.
759 (@xref{Filling}, for more information on @kbd{M-q}.) For these
760 commands, it is enough to the argument with a single @kbd{C-u}.
762 Some commands use the value of the argument as a repeat count, but
763 do something special when there is no argument. For example, the
764 command @kbd{C-k} (@code{kill-line}) with argument @var{n} kills
765 @var{n} lines, including their terminating newlines. But @kbd{C-k}
766 with no argument is special: it kills the text up to the next newline,
767 or, if point is right at the end of the line, it kills the newline
768 itself. Thus, two @kbd{C-k} commands with no arguments can kill a
769 nonblank line, just like @kbd{C-k} with an argument of one.
770 (@xref{Killing}, for more information on @kbd{C-k}.)
772 A few commands treat a plain @kbd{C-u} differently from an ordinary
773 argument. A few others may treat an argument of just a minus sign
774 differently from an argument of @minus{}1. These unusual cases are
775 described when they come up; they exist to make an individual command
776 more convenient, and they are documented in that command's
777 documentation string.
779 We use the term ``prefix argument'' as well as ``numeric argument'',
780 to emphasize that you type these argument before the command, and to
781 distinguish them from minibuffer arguments that come after the
785 @section Repeating a Command
786 @cindex repeating a command
788 Many simple commands, such as those invoked with a single key or
789 with @kbd{M-x @var{command-name} @key{RET}}, can be repeated by
790 invoking them with a numeric argument that serves as a repeat count
791 (@pxref{Arguments}). However, if the command you want to repeat
792 prompts for input, or uses a numeric argument in another way, that
797 The command @kbd{C-x z} (@code{repeat}) provides another way to repeat
798 an Emacs command many times. This command repeats the previous Emacs
799 command, whatever that was. Repeating a command uses the same arguments
800 that were used before; it does not read new arguments each time.
802 To repeat the command more than once, type additional @kbd{z}'s: each
803 @kbd{z} repeats the command one more time. Repetition ends when you
804 type a character other than @kbd{z}, or press a mouse button.
806 For example, suppose you type @kbd{C-u 2 0 C-d} to delete 20
807 characters. You can repeat that command (including its argument) three
808 additional times, to delete a total of 80 characters, by typing @kbd{C-x
809 z z z}. The first @kbd{C-x z} repeats the command once, and each
810 subsequent @kbd{z} repeats it once again.