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Killing means erasing text and copying it into the kill ring, from which it can be retrieved by yanking it. Some other systems that have recently become popular use the terms "cutting" and "pasting" for these operations.
The commonest way of moving or copying text with Emacs is to kill it and later yank it in one or more places. This is very safe because all the text killed recently is remembered, and it is versatile, because the many commands for killing syntactic units can also be used for moving those units. There are also other ways of copying text for special purposes.
Emacs has only one kill ring, so you can kill text in one buffer and yank it in another buffer.
Most commands which erase text from the buffer save it so that you can get it back if you change your mind, or move or copy it to other parts of the buffer. These commands are known as kill commands. The rest of the commands that erase text do not save it; they are known as delete commands. (This distinction is made only for erasure of text in the buffer.)
The delete commands include C-d (delete-char) and
DEL (delete-backward-char), which delete only one character at
a time, and those commands that delete only spaces or newlines. Commands
that can destroy significant amounts of nontrivial data generally kill.
The commands' names and individual descriptions use the words `kill'
and `delete' to say which they do. If you do a kill or delete command
by mistake, you can use the C-x u (undo) command to undo it
(see section Undoing Changes).
delete-char).
delete-backward-char).
delete-horizontal-space).
just-one-space).
delete-blank-lines).
delete-indentation).
The most basic delete commands are C-d (delete-char) and
DEL (delete-backward-char). C-d deletes the character
after point, the one the cursor is "on top of". Point doesn't move.
DEL deletes the character before the cursor, and moves point back.
Newlines can be deleted like any other characters in the buffer; deleting a
newline joins two lines. Actually, C-d and DEL aren't always
delete commands; if given an argument, they kill instead, since they can
erase more than one character this way.
The other delete commands are those which delete only formatting
characters: spaces, tabs and newlines. M-\ (delete-horizontal-space)
deletes all the spaces and tab characters before and after point.
M-SPC (just-one-space) does likewise but leaves a single
space after point, regardless of the number of spaces that existed
previously (even zero).
C-x C-o (delete-blank-lines) deletes all blank lines after
the current line, and if the current line is blank deletes all blank lines
preceding the current line as well (leaving one blank line, the current
line). M-^ (delete-indentation) joins the current line and
the previous line, or the current line and the next line if given an
argument, by deleting a newline and all surrounding spaces, possibly
leaving a single space. See section Indentation.
kill-line).
The simplest kill command is C-k. If given at the beginning of a line, it kills all the text on the line, leaving it blank. If given on a blank line, the blank line disappears. As a consequence, if you go to the front of a non-blank line and type C-k twice, the line disappears completely.
More generally, C-k kills from point up to the end of the line, unless it is at the end of a line. In that case it kills the newline following the line, thus merging the next line into the current one. Invisible spaces and tabs at the end of the line are ignored when deciding which case applies, so if point appears to be at the end of the line, you can be sure the newline will be killed.
If C-k is given a positive argument, it kills that many lines and the newlines that follow them (however, text on the current line before point is spared). With a negative argument, it kills back to a number of line beginnings. An argument of -2 means kill back to the second line beginning. If point is at the beginning of a line, that line beginning doesn't count, so C-u - 2 C-k with point at the front of a line kills the two previous lines.
C-k with an argument of zero kills all the text before point on the current line.
kill-region).
See section Words.
kill-word).
backward-kill-word).
backward-kill-sentence).
See section Sentences.
kill-sentence).
kill-sexp). See section Lists and Sexps.
zap-to-char).
A kill command which is very general is C-w (kill-region),
which kills everything between point and the mark. With this command, you
can kill any contiguous sequence of characters, if you first set the mark
at one end of them and go to the other end.
A convenient way of killing is combined with searching: M-z
(zap-to-char) reads a character and kills from point up to (but not
including) the next occurrence of that character in the buffer. If there
is no next occurrence, killing goes to the end of the buffer. A numeric
argument acts as a repeat count. A negative argument means to search
backward and kill text before point.
Other syntactic units can be killed: words, with M-DEL and M-d (see section Words); sexps, with C-M-k (see section Lists and Sexps); and sentences, with C-x DEL and M-k (see section Sentences).
Yanking is getting back text which was killed. This is what some systems call "pasting". The usual way to move or copy text is to kill it and then yank it one or more times.
yank).
yank-pop).
copy-region-as-kill).
append-next-kill).
All killed text is recorded in the kill ring, a list of blocks of text that have been killed. There is only one kill ring, used in all buffers, so you can kill text in one buffer and yank it in another buffer. This is the usual way to move text from one file to another. (See section Accumulating Text, for some other ways.)
The command C-y (yank) reinserts the text of the most recent
kill. It leaves the cursor at the end of the text. It sets the mark at
the beginning of the text. See section The Mark and the Region.
C-u C-y leaves the cursor in front of the text, and sets the mark after it. This is only if the argument is specified with just a C-u, precisely. Any other sort of argument, including C-u and digits, has an effect described below (under "Yanking Earlier Kills").
If you wish to copy a block of text, you might want to use M-w
(copy-region-as-kill), which copies the region into the kill ring
without removing it from the buffer. This is approximately equivalent to
C-w followed by C-y, except that M-w does not mark the
buffer as "modified" and does not temporarily change the screen.
Normally, each kill command pushes a new block onto the kill ring. However, two or more kill commands in a row combine their text into a single entry, so that a single C-y gets it all back as it was before it was killed. This means that you don't have to kill all the text in one command; you can keep killing line after line, or word after word, until you have killed it all, and you can still get it all back at once. (Thus we join television in leading people to kill thoughtlessly.)
Commands that kill forward from point add onto the end of the previous killed text. Commands that kill backward from point add onto the beginning. This way, any sequence of mixed forward and backward kill commands puts all the killed text into one entry without rearrangement. Numeric arguments do not break the sequence of appending kills. For example, suppose the buffer contains
This is the first line of sample text and here is the third.
with point at the beginning of the second line. If you type C-k C-u 2 M-DEL C-k, the first C-k kills the text `line of sample text', C-u 2 M-DEL kills `the first' with the newline that followed it, and the second C-k kills the newline after the second line. The result is that the buffer contains `This is and here is the third.' and a single kill entry contains `the firstRETline of sample textRET'---all the killed text, in its original order.
If a kill command is separated from the last kill command by other
commands (not just numeric arguments), it starts a new entry on the kill
ring. But you can force it to append by first typing the command
C-M-w (append-next-kill) in front of it. The C-M-w
tells the following command, if it is a kill command, to append the text it
kills to the last killed text, instead of starting a new entry. With
C-M-w, you can kill several separated pieces of text and accumulate
them to be yanked back in one place.
To recover killed text that is no longer the most recent kill, you need
the Meta-y (yank-pop) command. M-y can be used only
after a C-y or another M-y. It takes the text previously
yanked and replaces it with the text from an earlier kill. So, to recover
the text of the next-to-the-last kill, you first use C-y to recover
the last kill, and then use M-y to replace it with the previous
kill.
You can think in terms of a "last yank" pointer which points at an item in the kill ring. Each time you kill, the "last yank" pointer moves to the newly made item at the front of the ring. C-y yanks the item which the "last yank" pointer points to. M-y moves the "last yank" pointer to a different item, and the text in the buffer changes to match. Enough M-y commands can move the pointer to any item in the ring, so you can get any item into the buffer. Eventually the pointer reaches the end of the ring; the next M-y moves it to the first item again.
Yanking moves the "last yank" pointer around the ring, but it does not change the order of the entries in the ring, which always runs from the most recent kill at the front to the oldest one still remembered.
M-y can take a numeric argument, which tells it how many items to advance the "last yank" pointer by. A negative argument moves the pointer toward the front of the ring; from the front of the ring, it moves to the last entry and starts moving forward from there.
Once the text you are looking for is brought into the buffer, you can stop doing M-y commands and it will stay there. It's just a copy of the kill ring item, so editing it in the buffer does not change what's in the ring. As long as no new killing is done, the "last yank" pointer remains at the same place in the kill ring, so repeating C-y will yank another copy of the same old kill.
If you know how many M-y commands it would take to find the text you want, you can yank that text in one step using C-y with a numeric argument. C-y with an argument greater than one restores the text the specified number of entries back in the kill ring. Thus, C-u 2 C-y gets the next to the last block of killed text. It is equivalent to C-y M-y. C-y with a numeric argument starts counting from the "last yank" pointer, and sets the "last yank" pointer to the entry that it yanks.
The length of the kill ring is controlled by the variable
kill-ring-max; no more than that many blocks of killed text are
saved.
Usually we copy or move text by killing it and yanking it, but there are other ways that are useful for copying one block of text in many places, or for copying many scattered blocks of text into one place.
You can accumulate blocks of text from scattered locations either into a buffer or into a file if you like. These commands are described here. You can also use Emacs registers for storing and accumulating text. See section Registers.
append-to-buffer).
To accumulate text into a buffer, use the command C-x a buffername
(append-to-buffer), which inserts a copy of the region into the
buffer buffername, at the location of point in that buffer. If there
is no buffer with that name, one is created. If you append text into a
buffer which has been used for editing, the copied text goes into the
middle of the text of the buffer, wherever point happens to be in it.
Point in that buffer is left at the end of the copied text, so successive uses of C-x a accumulate the text in the specified buffer in the same order as they were copied. Strictly speaking, C-x a does not always append to the text already in the buffer; but if C-x a is the only command used to alter a buffer, it does always append to the existing text because point is always at the end.
M-x prepend-to-buffer is just like C-x a except that point in the other buffer is left before the copied text, so successive prependings add text in reverse order. M-x copy-to-buffer is similar except that any existing text in the other buffer is deleted, so the buffer is left containing just the text newly copied into it.
You can retrieve the accumulated text from that buffer with M-x insert-buffer; this too takes buffername as an argument. It inserts a copy of the text in buffer buffername into the selected buffer. You could alternatively select the other buffer for editing, perhaps moving text from it by killing or with C-x a. See section Using Multiple Buffers, for background information on buffers.
Instead of accumulating text within Emacs, in a buffer, you can append text directly into a file with M-x append-to-file, which takes file-name as an argument. It adds the text of the region to the end of the specified file. The file is changed immediately on disk. This command is normally used with files that are not being visited in Emacs. Using it on a file that Emacs is visiting can produce confusing results, because the text inside Emacs for that file will not change while the file itself changes.
The rectangle commands affect rectangular areas of the text: all the characters between a certain pair of columns, in a certain range of lines. Commands are provided to kill rectangles, yank killed rectangles, clear them out, or delete them. Rectangle commands are useful with text in multicolumnar formats, such as perhaps code with comments at the right, or for changing text into or out of such formats.
When you must specify a rectangle for a command to work on, you do it by putting the mark at one corner and point at the opposite corner. The rectangle thus specified is called the region-rectangle because it is controlled about the same way the region is controlled. But remember that a given combination of point and mark values can be interpreted either as specifying a region or as specifying a rectangle; it is up to the command that uses them to choose the interpretation.
The rectangle operations fall into two classes: commands deleting and moving rectangles, and commands for blank rectangles.
There are two ways to get rid of the text in a rectangle: you can discard the text (delete it) or save it as the "last killed" rectangle. The commands for these two ways are M-x delete-rectangle and M-x kill-rectangle. In either case, the portion of each line that falls inside the rectangle's boundaries is deleted, causing following text (if any) on the line to move left.
Note that "killing" a rectangle is not killing in the usual sense; the rectangle is not stored in the kill ring, but in a special place that can only record the most recent rectangle killed. This is because yanking a rectangle is so different from yanking linear text that different yank commands have to be used and yank-popping is hard to make sense of.
Inserting a rectangle is the opposite of deleting one. All you need to specify is where to put the upper left corner; that is done by putting point there. The rectangle's first line is inserted there, the rectangle's second line is inserted at a point one line vertically down, and so on. The number of lines affected is determined by the height of the saved rectangle.
To insert the last killed rectangle, type M-x yank-rectangle. This can be used to convert single-column lists into double-column lists; kill the second half of the list as a rectangle and then yank it beside the first line of the list.
There are two commands for working with blank rectangles: M-x clear-rectangle to blank out existing text, and M-x open-rectangle to insert a blank rectangle. Clearing a rectangle is equivalent to deleting it and then inserting as blank rectangle of the same size.
Rectangles can also be copied into and out of registers. See section Saving Rectangles in Registers.
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