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6bf7aab6 | 1 | @c This is part of the Emacs manual. |
67675c0f | 2 | @c Copyright (C) 1985, 86, 87, 93, 94, 95, 97, 2000 Free Software Foundation, Inc. |
6bf7aab6 DL |
3 | @c See file emacs.texi for copying conditions. |
4 | @node Basic, Minibuffer, Exiting, Top | |
5 | @chapter Basic Editing Commands | |
6 | ||
7 | @kindex C-h t | |
8 | @findex help-with-tutorial | |
9 | We now give the basics of how to enter text, make corrections, and | |
10 | save the text in a file. If this material is new to you, you might | |
11 | learn it more easily by running the Emacs learn-by-doing tutorial. To | |
12 | use the tutorial, run Emacs and type @kbd{Control-h t} | |
13 | (@code{help-with-tutorial}). | |
14 | ||
15 | To clear the screen and redisplay, type @kbd{C-l} (@code{recenter}). | |
16 | ||
17 | @menu | |
18 | ||
19 | * Inserting Text:: Inserting text by simply typing it. | |
20 | * Moving Point:: How to move the cursor to the place where you want to | |
21 | change something. | |
22 | * Erasing:: Deleting and killing text. | |
23 | * Undo:: Undoing recent changes in the text. | |
24 | * Files: Basic Files. Visiting, creating, and saving files. | |
25 | * Help: Basic Help. Asking what a character does. | |
26 | * Blank Lines:: Commands to make or delete blank lines. | |
27 | * Continuation Lines:: Lines too wide for the screen. | |
28 | * Position Info:: What page, line, row, or column is point on? | |
29 | * Arguments:: Numeric arguments for repeating a command. | |
30 | * Repeating:: A short-cut for repeating the previous command. | |
31 | @end menu | |
32 | ||
33 | @node Inserting Text | |
34 | @section Inserting Text | |
35 | ||
36 | @cindex insertion | |
37 | @cindex graphic characters | |
38 | To insert printing characters into the text you are editing, just type | |
39 | them. This inserts the characters you type into the buffer at the | |
40 | cursor (that is, at @dfn{point}; @pxref{Point}). The cursor moves | |
41 | forward, and any text after the cursor moves forward too. If the text | |
42 | in the buffer is @samp{FOOBAR}, with the cursor before the @samp{B}, | |
43 | then if you type @kbd{XX}, you get @samp{FOOXXBAR}, with the cursor | |
44 | still before the @samp{B}. | |
45 | ||
46 | To @dfn{delete} text you have just inserted, use @key{DEL}. @key{DEL} | |
47 | deletes the character @emph{before} the cursor (not the one that the cursor | |
48 | is on top of or under; that is the character @var{after} the cursor). The | |
49 | cursor and all characters after it move backwards. Therefore, if you type | |
50 | a printing character and then type @key{DEL}, they cancel out. | |
51 | ||
52 | @kindex RET | |
53 | @cindex newline | |
54 | To end a line and start typing a new one, type @key{RET}. This | |
55 | inserts a newline character in the buffer. If point is in the middle of | |
56 | a line, @key{RET} splits the line. Typing @key{DEL} when the cursor is | |
57 | at the beginning of a line deletes the preceding newline, thus joining | |
58 | the line with the preceding line. | |
59 | ||
60 | Emacs can split lines automatically when they become too long, if you | |
61 | turn on a special minor mode called @dfn{Auto Fill} mode. | |
62 | @xref{Filling}, for how to use Auto Fill mode. | |
63 | ||
64 | If you prefer to have text characters replace (overwrite) existing | |
65 | text rather than shove it to the right, you can enable Overwrite mode, | |
66 | a minor mode. @xref{Minor Modes}. | |
67 | ||
68 | @cindex quoting | |
69 | @kindex C-q | |
70 | @findex quoted-insert | |
71 | Direct insertion works for printing characters and @key{SPC}, but other | |
72 | characters act as editing commands and do not insert themselves. If you | |
73 | need to insert a control character or a character whose code is above 200 | |
74 | octal, you must @dfn{quote} it by typing the character @kbd{Control-q} | |
75 | (@code{quoted-insert}) first. (This character's name is normally written | |
76 | @kbd{C-q} for short.) There are two ways to use @kbd{C-q}:@refill | |
77 | ||
78 | @itemize @bullet | |
79 | @item | |
80 | @kbd{C-q} followed by any non-graphic character (even @kbd{C-g}) | |
81 | inserts that character. | |
82 | ||
83 | @item | |
84 | @kbd{C-q} followed by a sequence of octal digits inserts the character | |
85 | with the specified octal character code. You can use any number of | |
86 | octal digits; any non-digit terminates the sequence. If the terminating | |
87 | character is @key{RET}, it serves only to terminate the sequence; any | |
88 | other non-digit is itself used as input after terminating the sequence. | |
89 | (The use of octal sequences is disabled in ordinary non-binary Overwrite | |
90 | mode, to give you a convenient way to insert a digit instead of | |
91 | overwriting with it.) | |
92 | @end itemize | |
93 | ||
94 | @noindent | |
95 | When multibyte characters are enabled, octal codes 0200 through 0377 are | |
96 | not valid as characters; if you specify a code in this range, @kbd{C-q} | |
97 | assumes that you intend to use some ISO Latin-@var{n} character set, and | |
98 | converts the specified code to the corresponding Emacs character code. | |
99 | @xref{Enabling Multibyte}. You select @emph{which} ISO Latin character | |
100 | set though your choice of language environment (@pxref{Language | |
101 | Environments}). | |
102 | ||
103 | @vindex read-quoted-char-radix | |
104 | To use decimal or hexadecimal instead of octal, set the variable | |
105 | @code{read-quoted-char-radix} to 10 or 16. If the radix is greater than | |
106 | 10, some letters starting with @kbd{a} serve as part of a character | |
107 | code, just like digits. | |
108 | ||
109 | A numeric argument to @kbd{C-q} specifies how many copies of the | |
110 | quoted character should be inserted (@pxref{Arguments}). | |
111 | ||
112 | @findex newline | |
113 | @findex self-insert | |
114 | Customization information: @key{DEL} in most modes runs the command | |
115 | @code{delete-backward-char}; @key{RET} runs the command @code{newline}, and | |
116 | self-inserting printing characters run the command @code{self-insert}, | |
117 | which inserts whatever character was typed to invoke it. Some major modes | |
118 | rebind @key{DEL} to other commands. | |
119 | ||
120 | @node Moving Point | |
121 | @section Changing the Location of Point | |
122 | ||
123 | @cindex arrow keys | |
124 | @kindex LEFT | |
125 | @kindex RIGHT | |
126 | @kindex UP | |
127 | @kindex DOWN | |
128 | @cindex moving point | |
129 | @cindex movement | |
130 | @cindex cursor motion | |
131 | @cindex moving the cursor | |
132 | To do more than insert characters, you have to know how to move point | |
133 | (@pxref{Point}). The simplest way to do this is with arrow keys, or by | |
134 | clicking the left mouse button where you want to move to. | |
135 | ||
136 | There are also control and meta characters for cursor motion. Some | |
137 | are equivalent to the arrow keys (these date back to the days before | |
138 | terminals had arrow keys, and are usable on terminals which don't have | |
139 | them). Others do more sophisticated things. | |
140 | ||
141 | @kindex C-a | |
142 | @kindex C-e | |
143 | @kindex C-f | |
144 | @kindex C-b | |
145 | @kindex C-n | |
146 | @kindex C-p | |
147 | @kindex M-> | |
148 | @kindex M-< | |
149 | @kindex M-r | |
150 | @findex beginning-of-line | |
151 | @findex end-of-line | |
152 | @findex forward-char | |
153 | @findex backward-char | |
154 | @findex next-line | |
155 | @findex previous-line | |
156 | @findex beginning-of-buffer | |
157 | @findex end-of-buffer | |
158 | @findex goto-char | |
159 | @findex goto-line | |
160 | @findex move-to-window-line | |
161 | @table @kbd | |
162 | @item C-a | |
163 | Move to the beginning of the line (@code{beginning-of-line}). | |
164 | @item C-e | |
165 | Move to the end of the line (@code{end-of-line}). | |
166 | @item C-f | |
167 | Move forward one character (@code{forward-char}). | |
168 | @item C-b | |
169 | Move backward one character (@code{backward-char}). | |
170 | @item M-f | |
171 | Move forward one word (@code{forward-word}). | |
172 | @item M-b | |
173 | Move backward one word (@code{backward-word}). | |
174 | @item C-n | |
175 | Move down one line, vertically (@code{next-line}). This command | |
176 | attempts to keep the horizontal position unchanged, so if you start in | |
177 | the middle of one line, you end in the middle of the next. When on | |
178 | the last line of text, @kbd{C-n} creates a new line and moves onto it. | |
179 | @item C-p | |
180 | Move up one line, vertically (@code{previous-line}). | |
181 | @item M-r | |
182 | Move point to left margin, vertically centered in the window | |
183 | (@code{move-to-window-line}). Text does not move on the screen. | |
184 | ||
185 | A numeric argument says which screen line to place point on. It counts | |
186 | screen lines down from the top of the window (zero for the top line). A | |
187 | negative argument counts lines from the bottom (@minus{}1 for the bottom | |
188 | line). | |
189 | @item M-< | |
190 | Move to the top of the buffer (@code{beginning-of-buffer}). With | |
191 | numeric argument @var{n}, move to @var{n}/10 of the way from the top. | |
192 | @xref{Arguments}, for more information on numeric arguments.@refill | |
193 | @item M-> | |
194 | Move to the end of the buffer (@code{end-of-buffer}). | |
195 | @item M-x goto-char | |
196 | Read a number @var{n} and move point to buffer position @var{n}. | |
197 | Position 1 is the beginning of the buffer. | |
198 | @item M-x goto-line | |
199 | Read a number @var{n} and move point to line number @var{n}. Line 1 | |
200 | is the beginning of the buffer. | |
201 | @item C-x C-n | |
202 | @findex set-goal-column | |
203 | @kindex C-x C-n | |
204 | Use the current column of point as the @dfn{semipermanent goal column} for | |
205 | @kbd{C-n} and @kbd{C-p} (@code{set-goal-column}). Henceforth, those | |
206 | commands always move to this column in each line moved into, or as | |
207 | close as possible given the contents of the line. This goal column remains | |
208 | in effect until canceled. | |
209 | @item C-u C-x C-n | |
210 | Cancel the goal column. Henceforth, @kbd{C-n} and @kbd{C-p} once | |
211 | again try to stick to a fixed horizontal position, as usual. | |
212 | @end table | |
213 | ||
214 | @vindex track-eol | |
215 | If you set the variable @code{track-eol} to a non-@code{nil} value, | |
216 | then @kbd{C-n} and @kbd{C-p} when at the end of the starting line move | |
217 | to the end of another line. Normally, @code{track-eol} is @code{nil}. | |
218 | @xref{Variables}, for how to set variables such as @code{track-eol}. | |
219 | ||
220 | @vindex next-line-add-newlines | |
221 | Normally, @kbd{C-n} on the last line of a buffer appends a newline to | |
222 | it. If the variable @code{next-line-add-newlines} is @code{nil}, then | |
223 | @kbd{C-n} gets an error instead (like @kbd{C-p} on the first line). | |
224 | ||
225 | @node Erasing | |
226 | @section Erasing Text | |
227 | ||
228 | @table @kbd | |
229 | @item @key{DEL} | |
230 | Delete the character before point (@code{delete-backward-char}). | |
231 | @item C-d | |
232 | Delete the character after point (@code{delete-char}). | |
233 | @item C-k | |
234 | Kill to the end of the line (@code{kill-line}). | |
235 | @item M-d | |
236 | Kill forward to the end of the next word (@code{kill-word}). | |
237 | @item M-@key{DEL} | |
238 | Kill back to the beginning of the previous word | |
239 | (@code{backward-kill-word}). | |
240 | @end table | |
241 | ||
242 | @cindex killing characters and lines | |
243 | @cindex deleting characters and lines | |
244 | @cindex erasing characters and lines | |
245 | You already know about the @key{DEL} key which deletes the character | |
246 | before point (that is, before the cursor). Another key, @kbd{Control-d} | |
247 | (@kbd{C-d} for short), deletes the character after point (that is, the | |
248 | character that the cursor is on). This shifts the rest of the text on | |
249 | the line to the left. If you type @kbd{C-d} at the end of a line, it | |
250 | joins together that line and the next line. | |
251 | ||
252 | To erase a larger amount of text, use the @kbd{C-k} key, which kills a | |
253 | line at a time. If you type @kbd{C-k} at the beginning or middle of a | |
254 | line, it kills all the text up to the end of the line. If you type | |
255 | @kbd{C-k} at the end of a line, it joins that line and the next line. | |
256 | ||
257 | @xref{Killing}, for more flexible ways of killing text. | |
258 | ||
259 | @node Undo | |
260 | @section Undoing Changes | |
261 | @cindex undo | |
262 | @cindex changes, undoing | |
263 | ||
264 | You can undo all the recent changes in the buffer text, up to a | |
265 | certain point. Each buffer records changes individually, and the undo | |
266 | command always applies to the current buffer. Usually each editing | |
267 | command makes a separate entry in the undo records, but some commands | |
268 | such as @code{query-replace} make many entries, and very simple commands | |
269 | such as self-inserting characters are often grouped to make undoing less | |
270 | tedious. | |
271 | ||
272 | @table @kbd | |
273 | @item C-x u | |
274 | Undo one batch of changes---usually, one command worth (@code{undo}). | |
275 | @item C-_ | |
276 | The same. | |
277 | @item C-u C-x u | |
278 | Undo one batch of changes in the region. | |
279 | @end table | |
280 | ||
281 | @kindex C-x u | |
282 | @kindex C-_ | |
283 | @findex undo | |
284 | The command @kbd{C-x u} or @kbd{C-_} is how you undo. The first time | |
285 | you give this command, it undoes the last change. Point moves back to | |
286 | where it was before the command that made the change. | |
287 | ||
288 | Consecutive repetitions of @kbd{C-_} or @kbd{C-x u} undo earlier and | |
289 | earlier changes, back to the limit of the undo information available. | |
290 | If all recorded changes have already been undone, the undo command | |
291 | prints an error message and does nothing. | |
292 | ||
293 | Any command other than an undo command breaks the sequence of undo | |
294 | commands. Starting from that moment, the previous undo commands become | |
295 | ordinary changes that you can undo. Thus, to redo changes you have | |
296 | undone, type @kbd{C-f} or any other command that will harmlessly break | |
297 | the sequence of undoing, then type more undo commands. | |
298 | ||
299 | @cindex selective undo | |
300 | @kindex C-u C-x u | |
301 | Ordinary undo applies to all changes made in the current buffer. You | |
302 | can also perform @dfn{selective undo}, limited to the current region. | |
303 | To do this, specify the region you want, then run the @code{undo} | |
304 | command with a prefix argument (the value does not matter): @kbd{C-u C-x | |
305 | u} or @kbd{C-u C-_}. This undoes the most recent change in the region. | |
306 | To undo further changes in the same region, repeat the @code{undo} | |
307 | command (no prefix argument is needed). In Transient Mark mode, any use | |
308 | of @code{undo} when there is an active region performs selective undo; | |
309 | you do not need a prefix argument. | |
310 | ||
311 | If you notice that a buffer has been modified accidentally, the | |
312 | easiest way to recover is to type @kbd{C-_} repeatedly until the stars | |
313 | disappear from the front of the mode line. At this time, all the | |
314 | modifications you made have been canceled. Whenever an undo command | |
315 | makes the stars disappear from the mode line, it means that the buffer | |
316 | contents are the same as they were when the file was last read in or | |
317 | saved. | |
318 | ||
319 | If you do not remember whether you changed the buffer deliberately, | |
320 | type @kbd{C-_} once. When you see the last change you made undone, you | |
321 | will see whether it was an intentional change. If it was an accident, | |
322 | leave it undone. If it was deliberate, redo the change as described | |
323 | above. | |
324 | ||
325 | Not all buffers record undo information. Buffers whose names start with | |
326 | spaces don't; these buffers are used internally by Emacs and its extensions | |
327 | to hold text that users don't normally look at or edit. | |
328 | ||
329 | You cannot undo mere cursor motion; only changes in the buffer | |
330 | contents save undo information. However, some cursor motion commands | |
331 | set the mark, so if you use these commands from time to time, you can | |
332 | move back to the neighborhoods you have moved through by popping the | |
333 | mark ring (@pxref{Mark Ring}). | |
334 | ||
335 | @vindex undo-limit | |
336 | @vindex undo-strong-limit | |
337 | @cindex undo limit | |
338 | When the undo information for a buffer becomes too large, Emacs | |
339 | discards the oldest undo information from time to time (during garbage | |
340 | collection). You can specify how much undo information to keep by | |
341 | setting two variables: @code{undo-limit} and @code{undo-strong-limit}. | |
342 | Their values are expressed in units of bytes of space. | |
343 | ||
344 | The variable @code{undo-limit} sets a soft limit: Emacs keeps undo | |
345 | data for enough commands to reach this size, and perhaps exceed it, but | |
346 | does not keep data for any earlier commands beyond that. Its default | |
347 | value is 20000. The variable @code{undo-strong-limit} sets a stricter | |
348 | limit: the command which pushes the size past this amount is itself | |
349 | forgotten. Its default value is 30000. | |
350 | ||
351 | Regardless of the values of those variables, the most recent change is | |
352 | never discarded, so there is no danger that garbage collection occurring | |
353 | right after an unintentional large change might prevent you from undoing | |
354 | it. | |
355 | ||
356 | The reason the @code{undo} command has two keys, @kbd{C-x u} and | |
357 | @kbd{C-_}, set up to run it is that it is worthy of a single-character | |
358 | key, but on some keyboards it is not obvious how to type @kbd{C-_}. | |
359 | @kbd{C-x u} is an alternative you can type straightforwardly on any | |
360 | terminal. | |
361 | ||
362 | @node Basic Files | |
363 | @section Files | |
364 | ||
365 | The commands described above are sufficient for creating and altering | |
366 | text in an Emacs buffer; the more advanced Emacs commands just make | |
367 | things easier. But to keep any text permanently you must put it in a | |
368 | @dfn{file}. Files are named units of text which are stored by the | |
369 | operating system for you to retrieve later by name. To look at or use | |
370 | the contents of a file in any way, including editing the file with | |
371 | Emacs, you must specify the file name. | |
372 | ||
373 | Consider a file named @file{/usr/rms/foo.c}. In Emacs, to begin editing | |
374 | this file, type | |
375 | ||
376 | @example | |
377 | C-x C-f /usr/rms/foo.c @key{RET} | |
378 | @end example | |
379 | ||
380 | @noindent | |
381 | Here the file name is given as an @dfn{argument} to the command @kbd{C-x | |
382 | C-f} (@code{find-file}). That command uses the @dfn{minibuffer} to | |
383 | read the argument, and you type @key{RET} to terminate the argument | |
384 | (@pxref{Minibuffer}).@refill | |
385 | ||
386 | Emacs obeys the command by @dfn{visiting} the file: creating a buffer, | |
387 | copying the contents of the file into the buffer, and then displaying | |
388 | the buffer for you to edit. If you alter the text, you can @dfn{save} | |
389 | the new text in the file by typing @kbd{C-x C-s} (@code{save-buffer}). | |
390 | This makes the changes permanent by copying the altered buffer contents | |
391 | back into the file @file{/usr/rms/foo.c}. Until you save, the changes | |
392 | exist only inside Emacs, and the file @file{foo.c} is unaltered. | |
393 | ||
394 | To create a file, just visit the file with @kbd{C-x C-f} as if it | |
395 | already existed. This creates an empty buffer in which you can insert | |
396 | the text you want to put in the file. The file is actually created when | |
397 | you save this buffer with @kbd{C-x C-s}. | |
398 | ||
399 | Of course, there is a lot more to learn about using files. @xref{Files}. | |
400 | ||
401 | @node Basic Help | |
402 | @section Help | |
403 | ||
404 | @cindex getting help with keys | |
405 | If you forget what a key does, you can find out with the Help | |
406 | character, which is @kbd{C-h} (or @key{F1}, which is an alias for | |
407 | @kbd{C-h}). Type @kbd{C-h k} followed by the key you want to know | |
408 | about; for example, @kbd{C-h k C-n} tells you all about what @kbd{C-n} | |
409 | does. @kbd{C-h} is a prefix key; @kbd{C-h k} is just one of its | |
410 | subcommands (the command @code{describe-key}). The other subcommands of | |
411 | @kbd{C-h} provide different kinds of help. Type @kbd{C-h} twice to get | |
412 | a description of all the help facilities. @xref{Help}.@refill | |
413 | ||
414 | @node Blank Lines | |
415 | @section Blank Lines | |
416 | ||
417 | @cindex inserting blank lines | |
418 | @cindex deleting blank lines | |
419 | Here are special commands and techniques for putting in and taking out | |
420 | blank lines. | |
421 | ||
422 | @c widecommands | |
423 | @table @kbd | |
424 | @item C-o | |
425 | Insert one or more blank lines after the cursor (@code{open-line}). | |
426 | @item C-x C-o | |
427 | Delete all but one of many consecutive blank lines | |
428 | (@code{delete-blank-lines}). | |
429 | @end table | |
430 | ||
431 | @kindex C-o | |
432 | @kindex C-x C-o | |
433 | @cindex blank lines | |
434 | @findex open-line | |
435 | @findex delete-blank-lines | |
436 | When you want to insert a new line of text before an existing line, you | |
437 | can do it by typing the new line of text, followed by @key{RET}. | |
438 | However, it may be easier to see what you are doing if you first make a | |
439 | blank line and then insert the desired text into it. This is easy to do | |
440 | using the key @kbd{C-o} (@code{open-line}), which inserts a newline | |
441 | after point but leaves point in front of the newline. After @kbd{C-o}, | |
442 | type the text for the new line. @kbd{C-o F O O} has the same effect as | |
443 | @w{@kbd{F O O @key{RET}}}, except for the final location of point. | |
444 | ||
445 | You can make several blank lines by typing @kbd{C-o} several times, or | |
446 | by giving it a numeric argument to tell it how many blank lines to make. | |
447 | @xref{Arguments}, for how. If you have a fill prefix, then @kbd{C-o} | |
448 | command inserts the fill prefix on the new line, when you use it at the | |
449 | beginning of a line. @xref{Fill Prefix}. | |
450 | ||
451 | The easy way to get rid of extra blank lines is with the command | |
452 | @kbd{C-x C-o} (@code{delete-blank-lines}). @kbd{C-x C-o} in a run of | |
453 | several blank lines deletes all but one of them. @kbd{C-x C-o} on a | |
454 | solitary blank line deletes that blank line. When point is on a | |
455 | nonblank line, @kbd{C-x C-o} deletes any blank lines following that | |
456 | nonblank line. | |
457 | ||
458 | @node Continuation Lines | |
459 | @section Continuation Lines | |
460 | ||
461 | @cindex continuation line | |
462 | @cindex wrapping | |
463 | @cindex line wrapping | |
464 | If you add too many characters to one line without breaking it with | |
465 | @key{RET}, the line will grow to occupy two (or more) lines on the screen, | |
466 | with a @samp{\} at the extreme right margin of all but the last of them. | |
467 | The @samp{\} says that the following screen line is not really a distinct | |
468 | line in the text, but just the @dfn{continuation} of a line too long to fit | |
469 | the screen. Continuation is also called @dfn{line wrapping}. | |
470 | ||
471 | Sometimes it is nice to have Emacs insert newlines automatically when | |
472 | a line gets too long. Continuation on the screen does not do that. Use | |
473 | Auto Fill mode (@pxref{Filling}) if that's what you want. | |
474 | ||
475 | @vindex truncate-lines | |
476 | @cindex truncation | |
477 | As an alternative to continuation, Emacs can display long lines by | |
478 | @dfn{truncation}. This means that all the characters that do not fit in | |
479 | the width of the screen or window do not appear at all. They remain in | |
480 | the buffer, temporarily invisible. @samp{$} is used in the last column | |
481 | instead of @samp{\} to inform you that truncation is in effect. | |
482 | ||
483 | Truncation instead of continuation happens whenever horizontal | |
484 | scrolling is in use, and optionally in all side-by-side windows | |
485 | (@pxref{Windows}). You can enable truncation for a particular buffer by | |
486 | setting the variable @code{truncate-lines} to non-@code{nil} in that | |
487 | buffer. (@xref{Variables}.) Altering the value of | |
488 | @code{truncate-lines} makes it local to the current buffer; until that | |
489 | time, the default value is in effect. The default is initially | |
490 | @code{nil}. @xref{Locals}. | |
491 | ||
492 | @xref{Display Vars}, for additional variables that affect how text is | |
493 | displayed. | |
494 | ||
495 | @node Position Info | |
496 | @section Cursor Position Information | |
497 | ||
498 | Here are commands to get information about the size and position of | |
499 | parts of the buffer, and to count lines. | |
500 | ||
501 | @table @kbd | |
502 | @item M-x what-page | |
503 | Print page number of point, and line number within page. | |
504 | @item M-x what-line | |
505 | Print line number of point in the buffer. | |
506 | @item M-x line-number-mode | |
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507 | @itemx M-x column-number-mode |
508 | Toggle automatic display of current line number or column number. | |
509 | @xref{Optional Mode Line}. | |
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510 | @item M-= |
511 | Print number of lines in the current region (@code{count-lines-region}). | |
512 | @xref{Mark}, for information about the region. | |
513 | @item C-x = | |
514 | Print character code of character after point, character position of | |
515 | point, and column of point (@code{what-cursor-position}). | |
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516 | @item M-x hl-line-mode |
517 | Highlighting the current line. | |
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518 | @end table |
519 | ||
520 | @findex what-page | |
521 | @findex what-line | |
522 | @cindex line number commands | |
523 | @cindex location of point | |
524 | @cindex cursor location | |
525 | @cindex point location | |
526 | There are two commands for working with line numbers. @kbd{M-x | |
527 | what-line} computes the current line number and displays it in the echo | |
528 | area. To go to a given line by number, use @kbd{M-x goto-line}; it | |
529 | prompts you for the number. These line numbers count from one at the | |
530 | beginning of the buffer. | |
531 | ||
532 | You can also see the current line number in the mode line; @xref{Mode | |
533 | Line}. If you narrow the buffer, then the line number in the mode line | |
534 | is relative to the accessible portion (@pxref{Narrowing}). By contrast, | |
535 | @code{what-line} shows both the line number relative to the narrowed | |
536 | region and the line number relative to the whole buffer. | |
537 | ||
538 | By contrast, @kbd{M-x what-page} counts pages from the beginning of | |
539 | the file, and counts lines within the page, printing both numbers. | |
540 | @xref{Pages}. | |
541 | ||
542 | @kindex M-= | |
543 | @findex count-lines-region | |
544 | While on this subject, we might as well mention @kbd{M-=} (@code{count-lines-region}), | |
545 | which prints the number of lines in the region (@pxref{Mark}). | |
546 | @xref{Pages}, for the command @kbd{C-x l} which counts the lines in the | |
547 | current page. | |
548 | ||
549 | @kindex C-x = | |
550 | @findex what-cursor-position | |
551 | The command @kbd{C-x =} (@code{what-cursor-position}) can be used to find out | |
552 | the column that the cursor is in, and other miscellaneous information about | |
553 | point. It prints a line in the echo area that looks like this: | |
554 | ||
555 | @smallexample | |
556 | Char: c (0143, 99, 0x63) point=21044 of 26883(78%) column 53 | |
557 | @end smallexample | |
558 | ||
559 | @noindent | |
560 | (In fact, this is the output produced when point is before the | |
561 | @samp{column} in the example.) | |
562 | ||
563 | The four values after @samp{Char:} describe the character that follows | |
564 | point, first by showing it and then by giving its character code in | |
565 | octal, decimal and hex. For a non-ASCII multibyte character, these are | |
566 | followed by @samp{ext} and the character's representation, in hex, in | |
567 | the buffer's coding system, if that coding system encodes the character | |
568 | safely and with a single byte (@pxref{Coding Systems}). If the | |
569 | character's encoding is longer than one byte, Emacs shows @samp{ext ...}. | |
570 | ||
571 | @samp{point=} is followed by the position of point expressed as a character | |
572 | count. The front of the buffer counts as position 1, one character later | |
573 | as 2, and so on. The next, larger, number is the total number of characters | |
574 | in the buffer. Afterward in parentheses comes the position expressed as a | |
575 | percentage of the total size. | |
576 | ||
577 | @samp{column} is followed by the horizontal position of point, in | |
578 | columns from the left edge of the window. | |
579 | ||
580 | If the buffer has been narrowed, making some of the text at the | |
581 | beginning and the end temporarily inaccessible, @kbd{C-x =} prints | |
582 | additional text describing the currently accessible range. For example, it | |
583 | might display this: | |
584 | ||
585 | @smallexample | |
586 | Char: C (0103, 67, 0x43) point=252 of 889(28%) <231 - 599> column 0 | |
587 | @end smallexample | |
588 | ||
589 | @noindent | |
590 | where the two extra numbers give the smallest and largest character | |
591 | position that point is allowed to assume. The characters between those | |
592 | two positions are the accessible ones. @xref{Narrowing}. | |
593 | ||
594 | If point is at the end of the buffer (or the end of the accessible | |
595 | part), the @w{@kbd{C-x =}} output does not describe a character after | |
596 | point. The output might look like this: | |
597 | ||
598 | @smallexample | |
599 | point=26957 of 26956(100%) column 0 | |
600 | @end smallexample | |
601 | ||
602 | @w{@kbd{C-u C-x =}} displays additional information about a character, | |
603 | in place of the buffer coordinates and column: the character set name | |
604 | and the codes that identify the character within that character set; | |
605 | ASCII characters are identified as belonging to the @code{ASCII} | |
606 | character set. In addition, the full character encoding, even if it | |
607 | takes more than a single byte, is shown after @samp{ext}. Here's an | |
608 | example for a Latin-1 character A with a grave accent in a buffer whose | |
609 | coding system is iso-2022-7bit@footnote{On terminals that support | |
610 | Latin-1 characters, the character shown after @samp{Char:} is displayed | |
611 | as the actual glyph of A with grave accent.}: | |
612 | ||
613 | @example | |
614 | Char: @`A (04300, 2240, 0x8c0, ext ESC , A @@) (latin-iso8859-1 64) | |
615 | @end example | |
616 | ||
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617 | @findex hl-line-mode |
618 | @findex blink-cursor-mode | |
619 | @cindex cursor, locating visually | |
620 | @cindex cursor, blinking | |
621 | @kbd{M-x hl-line-mode} turns on a global minor mode which highlights the | |
622 | line about point in the selected window (on terminals which support | |
623 | highlighting). Some people find this convenient. If you find the | |
624 | cursor difficult to spot, you might try changing its color by | |
625 | customizing the @code{cursor} face or rely on (the default) | |
626 | @code{blink-cursor-mode}. Cursor color and blinking can be conrolled | |
627 | via the @code{cursor} Custom group. | |
628 | ||
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629 | @node Arguments |
630 | @section Numeric Arguments | |
631 | @cindex numeric arguments | |
632 | @cindex prefix arguments | |
633 | @cindex arguments, numeric | |
634 | @cindex arguments, prefix | |
635 | ||
636 | In mathematics and computer usage, the word @dfn{argument} means | |
637 | ``data provided to a function or operation.'' You can give any Emacs | |
638 | command a @dfn{numeric argument} (also called a @dfn{prefix argument}). | |
639 | Some commands interpret the argument as a repetition count. For | |
640 | example, @kbd{C-f} with an argument of ten moves forward ten characters | |
641 | instead of one. With these commands, no argument is equivalent to an | |
642 | argument of one. Negative arguments tell most such commands to move or | |
643 | act in the opposite direction. | |
644 | ||
645 | @kindex M-1 | |
646 | @kindex M-@t{-} | |
647 | @findex digit-argument | |
648 | @findex negative-argument | |
649 | If your terminal keyboard has a @key{META} key, the easiest way to | |
650 | specify a numeric argument is to type digits and/or a minus sign while | |
651 | holding down the @key{META} key. For example, | |
652 | @example | |
653 | M-5 C-n | |
654 | @end example | |
655 | @noindent | |
656 | would move down five lines. The characters @kbd{Meta-1}, @kbd{Meta-2}, | |
657 | and so on, as well as @kbd{Meta--}, do this because they are keys bound | |
658 | to commands (@code{digit-argument} and @code{negative-argument}) that | |
659 | are defined to contribute to an argument for the next command. Digits | |
660 | and @kbd{-} modified with Control, or Control and Meta, also specify | |
661 | numeric arguments. | |
662 | ||
663 | @kindex C-u | |
664 | @findex universal-argument | |
665 | Another way of specifying an argument is to use the @kbd{C-u} | |
666 | (@code{universal-argument}) command followed by the digits of the | |
667 | argument. With @kbd{C-u}, you can type the argument digits without | |
668 | holding down modifier keys; @kbd{C-u} works on all terminals. To type a | |
669 | negative argument, type a minus sign after @kbd{C-u}. Just a minus sign | |
670 | without digits normally means @minus{}1. | |
671 | ||
672 | @kbd{C-u} followed by a character which is neither a digit nor a minus | |
673 | sign has the special meaning of ``multiply by four.'' It multiplies the | |
674 | argument for the next command by four. @kbd{C-u} twice multiplies it by | |
675 | sixteen. Thus, @kbd{C-u C-u C-f} moves forward sixteen characters. This | |
676 | is a good way to move forward ``fast,'' since it moves about 1/5 of a line | |
677 | in the usual size screen. Other useful combinations are @kbd{C-u C-n}, | |
678 | @kbd{C-u C-u C-n} (move down a good fraction of a screen), @kbd{C-u C-u | |
679 | C-o} (make ``a lot'' of blank lines), and @kbd{C-u C-k} (kill four | |
680 | lines).@refill | |
681 | ||
682 | Some commands care only about whether there is an argument, and not about | |
683 | its value. For example, the command @kbd{M-q} (@code{fill-paragraph}) with | |
684 | no argument fills text; with an argument, it justifies the text as well. | |
685 | (@xref{Filling}, for more information on @kbd{M-q}.) Plain @kbd{C-u} is a | |
686 | handy way of providing an argument for such commands. | |
687 | ||
688 | Some commands use the value of the argument as a repeat count, but do | |
689 | something peculiar when there is no argument. For example, the command | |
690 | @kbd{C-k} (@code{kill-line}) with argument @var{n} kills @var{n} lines, | |
691 | including their terminating newlines. But @kbd{C-k} with no argument is | |
692 | special: it kills the text up to the next newline, or, if point is right at | |
693 | the end of the line, it kills the newline itself. Thus, two @kbd{C-k} | |
694 | commands with no arguments can kill a nonblank line, just like @kbd{C-k} | |
695 | with an argument of one. (@xref{Killing}, for more information on | |
696 | @kbd{C-k}.)@refill | |
697 | ||
698 | A few commands treat a plain @kbd{C-u} differently from an ordinary | |
699 | argument. A few others may treat an argument of just a minus sign | |
700 | differently from an argument of @minus{}1. These unusual cases are | |
701 | described when they come up; they are always for reasons of convenience | |
702 | of use of the individual command. | |
703 | ||
704 | You can use a numeric argument to insert multiple copies of a | |
705 | character. This is straightforward unless the character is a digit; for | |
706 | example, @kbd{C-u 6 4 a} inserts 64 copies of the character @samp{a}. | |
707 | But this does not work for inserting digits; @kbd{C-u 6 4 1} specifies | |
708 | an argument of 641, rather than inserting anything. To separate the | |
709 | digit to insert from the argument, type another @kbd{C-u}; for example, | |
710 | @kbd{C-u 6 4 C-u 1} does insert 64 copies of the character @samp{1}. | |
711 | ||
712 | We use the term ``prefix argument'' as well as ``numeric argument'' to | |
713 | emphasize that you type the argument before the command, and to | |
714 | distinguish these arguments from minibuffer arguments that come after | |
715 | the command. | |
716 | ||
717 | @node Repeating | |
718 | @section Repeating a Command | |
719 | @cindex repeating a command | |
720 | ||
721 | @kindex C-x z | |
722 | @findex repeat | |
723 | The command @kbd{C-x z} (@code{repeat}) provides another way to repeat | |
724 | an Emacs command many times. This command repeats the previous Emacs | |
725 | command, whatever that was. Repeating a command uses the same arguments | |
726 | that were used before; it does not read new arguments each time. | |
727 | ||
728 | To repeat the command more than once, type additional @kbd{z}'s: each | |
729 | @kbd{z} repeats the command one more time. Repetition ends when you | |
730 | type a character other than @kbd{z}, or press a mouse button. | |
731 | ||
732 | For example, suppose you type @kbd{C-u 2 0 C-d} to delete 20 | |
733 | characters. You can repeat that command (including its argument) three | |
734 | additional times, to delete a total of 80 characters, by typing @kbd{C-x | |
735 | z z z}. The first @kbd{C-x z} repeats the command once, and each | |
736 | subsequent @kbd{z} repeats it once again. | |
737 |