Merge from trunk.

[gnu-emacs] / doc / emacs / killing.texi

@c This is part of the Emacs manual.
@c Copyright (C) 1985-1987, 1993-1995, 1997, 2000-2011
@c   Free Software Foundation, Inc.
@c See file emacs.texi for copying conditions.

@node Killing, Registers, Mark, Top
@chapter Killing and Moving Text

  In Emacs, @dfn{killing} means erasing text and copying it into the
@dfn{kill ring}.  @dfn{Yanking} means bringing text from the kill ring
back into the buffer.  (Some applications use the terms ``cutting''
and ``pasting'' for similar operations.)  The kill ring is so-named
because it can be visualized as a set of blocks of text arranged in a
ring, which you can access in cyclic order.  @xref{Kill Ring}.

  Killing and yanking are the most common way to move or copy text
within Emacs.  It is very versatile, because there are commands for
killing many different types of syntactic units.

@menu
* Deletion and Killing:: Commands that remove text.
* Yanking::              Commands that insert text.
* Cut and Paste::        Clipboard and selections on graphical displays.
* Accumulating Text::    Other methods to add text to the buffer.
* Rectangles::           Operating on text in rectangular areas.
* CUA Bindings::         Using @kbd{C-x}/@kbd{C-c}/@kbd{C-v} to kill and yank.
@end menu

@node Deletion and Killing
@section Deletion and Killing

@cindex killing text
@cindex cutting text
@cindex deletion
  Most commands which erase text from the buffer save it in the kill
ring.  These are known as @dfn{kill} commands, and their names
normally contain the word @samp{kill} (e.g. @code{kill-line}).  The
kill ring stores several recent kills, not just the last one, so
killing is a very safe operation: you don't have to worry much about
losing text that you previously killed.  The kill ring is shared by
all buffers, so text that is killed in one buffer can be yanked into
another buffer.

  When you use @kbd{C-/} (@code{undo}) to undo a kill command
(@pxref{Undo}), that brings the killed text back into the buffer, but
does not remove it from the kill ring.

  On graphical displays, killing text also copies it to the system
clipboard.  @xref{Cut and Paste}.

  Commands that erase text but do not save it in the kill ring are
known as @dfn{delete} commands; their names usually contain the word
@samp{delete}.  These include @kbd{C-d} (@code{delete-char}) and
@key{DEL} (@code{delete-backward-char}), which delete only one
character at a time, and those commands that delete only spaces or
newlines.  Commands that can erase significant amounts of nontrivial
data generally do a kill operation instead.

  You can also use the mouse to kill and yank.  @xref{Cut and Paste}.

@menu
* Deletion::            Commands for deleting small amounts of text and
                          blank areas.
* Killing by Lines::    How to kill entire lines of text at one time.
* Other Kill Commands:: Commands to kill large regions of text and
                          syntactic units such as words and sentences.
* Kill Options::        Options that affect killing.
@end menu

@node Deletion
@subsection Deletion
@findex delete-backward-char
@findex delete-char

  Deletion means erasing text and not saving it in the kill ring.  For
the most part, the Emacs commands that delete text are those that
erase just one character or only whitespace.

@table @kbd
@item C-d
@itemx @key{Delete}
Delete next character (@code{delete-char}).
@item @key{DEL}
@itemx @key{Backspace}
Delete previous character (@code{delete-backward-char}).
@item M-\
Delete spaces and tabs around point (@code{delete-horizontal-space}).
@item M-@key{SPC}
Delete spaces and tabs around point, leaving one space
(@code{just-one-space}).
@item C-x C-o
Delete blank lines around the current line (@code{delete-blank-lines}).
@item M-^
Join two lines by deleting the intervening newline, along with any
indentation following it (@code{delete-indentation}).
@end table

  We have already described the basic deletion commands @kbd{C-d}
(@code{delete-char}) and @key{DEL} (@code{delete-backward-char}).
@xref{Erasing}.

@kindex M-\
@findex delete-horizontal-space
@kindex M-SPC
@findex just-one-space
  The other delete commands are those that delete only whitespace
characters: spaces, tabs and newlines.  @kbd{M-\}
(@code{delete-horizontal-space}) deletes all the spaces and tab
characters before and after point.  With a prefix argument, this only
deletes spaces and tab characters before point.  @kbd{M-@key{SPC}}
(@code{just-one-space}) does likewise but leaves a single space after
point, regardless of the number of spaces that existed previously
(even if there were none before).  With a numeric argument @var{n}, it
leaves @var{n} spaces after point.

  @kbd{C-x C-o} (@code{delete-blank-lines}) deletes all blank lines
after the current line.  If the current line is blank, it deletes all
blank lines preceding the current line as well (leaving one blank line,
the current line).  On a solitary blank line, it deletes that line.

  @kbd{M-^} (@code{delete-indentation}) joins the current line and the
previous line, by deleting a newline and all surrounding spaces, usually
leaving a single space.  @xref{Indentation,M-^}.

@node Killing by Lines
@subsection Killing by Lines

@table @kbd
@item C-k
Kill rest of line or one or more lines (@code{kill-line}).
@item C-S-backspace
Kill an entire line at once (@code{kill-whole-line})
@end table

@kindex C-k
@findex kill-line
  The simplest kill command is @kbd{C-k} (@code{kill-line}).  If used
at the end of a line, it kills the line-ending newline character,
merging the next line into the current one (thus, a blank line is
entirely removed).  Otherwise, @kbd{C-k} kills all the text from point
up to the end of the line; if point was originally at the beginning of
the line, this leaves the line blank.

  Spaces and tabs at the end of the line are ignored when deciding
which case applies.  As long as point is after the last visible
character in the line, you can be sure that @kbd{C-k} will kill the
newline.  To kill an entire non-blank line, go to the beginning and
type @kbd{C-k} twice.

  In this context, ``line'' means a logical text line, not a screen
line (@pxref{Continuation Lines}).

  When @kbd{C-k} is given a positive argument @var{n}, it kills
@var{n} lines and the newlines that follow them (text on the current
line before point is not killed).  With a negative argument
@minus{}@var{n}, it kills @var{n} lines preceding the current line,
together with the text on the current line before point.  @kbd{C-k}
with an argument of zero kills the text before point on the current
line.

@vindex kill-whole-line
  If the variable @code{kill-whole-line} is non-@code{nil}, @kbd{C-k} at
the very beginning of a line kills the entire line including the
following newline.  This variable is normally @code{nil}.

@kindex C-S-backspace
@findex kill-whole-line
  @kbd{C-S-backspace} (@code{kill-whole-line}) kills a whole line
including its newline, regardless of the position of point within the
line.  Note that many text terminals will prevent you from typing the
key sequence @kbd{C-S-backspace}.

@node Other Kill Commands
@subsection Other Kill Commands
@findex kill-region
@kindex C-w

@table @kbd
@item C-w
Kill region (@code{kill-region}).  @xref{Mark}.
@item M-w
Save region as last killed text without actually killing it
(@code{kill-ring-save}).  Some programs call this ``copying.''
@item M-d
Kill word (@code{kill-word}).  @xref{Words}.
@item M-@key{DEL}
Kill word backwards (@code{backward-kill-word}).
@item C-x @key{DEL}
Kill back to beginning of sentence (@code{backward-kill-sentence}).
@xref{Sentences}.
@item M-k
Kill to end of sentence (@code{kill-sentence}).
@item C-M-k
Kill the following balanced expression (@code{kill-sexp}).  @xref{Expressions}.
@item M-z @var{char}
Kill through the next occurrence of @var{char} (@code{zap-to-char}).
@end table

  Apart from @kbd{C-k}, the most commonly-used kill command is
@kbd{C-w} (@code{kill-region}), which kills the text in the region
(i.e., between point and mark).  @xref{Mark}.  If the mark is inactive
when you type @kbd{C-w}, it first reactivates the mark where it was
last set.  The mark is deactivated at the end of the command.

@kindex M-w
@findex kill-ring-save
  @kbd{M-w} (@code{kill-ring-save}) copies the region into the kill
ring without removing it from the buffer.

  Emacs also provides commands to kill specific syntactic units:
words, with @kbd{M-@key{DEL}} and @kbd{M-d} (@pxref{Words}); balanced
expressions, with @kbd{C-M-k} (@pxref{Expressions}); and sentences,
with @kbd{C-x @key{DEL}} and @kbd{M-k} (@pxref{Sentences}).

@kindex M-z
@findex zap-to-char
  The command @kbd{M-z} (@code{zap-to-char}) combines killing with
searching: it reads a character and kills from point up to (and
including) the next occurrence of that character in the buffer.  A
numeric argument acts as a repeat count; a negative argument means to
search backward and kill text before point.

@node Kill Options
@subsection Options for Killing

@vindex kill-read-only-ok
@cindex read-only text, killing
  Some specialized buffers contain @dfn{read-only text}, which cannot
be modified and therefore cannot be killed.  The kill commands work
specially in a read-only buffer: they move over text and copy it to
the kill ring, without actually deleting it from the buffer.
Normally, they also beep and display an error message when this
happens.  But if you set the variable @code{kill-read-only-ok} to a
non-@code{nil} value, they just print a message in the echo area to
explain why the text has not been erased.

@vindex kill-do-not-save-duplicates
  If you change the variable @code{kill-do-not-save-duplicates} to a
non-@code{nil} value, identical subsequent kills yield a single
kill-ring entry, without duplication.

@node Yanking
@section Yanking
@cindex moving text
@cindex copying text
@cindex kill ring
@cindex yanking
@cindex pasting

  @dfn{Yanking} means reinserting text previously killed.  The usual
way to move or copy text is to kill it and then yank it elsewhere one
or more times.

@table @kbd
@item C-y
Yank last killed text (@code{yank}).
@item M-y
Replace text just yanked with an earlier batch of killed text
(@code{yank-pop}).
@item C-M-w
Append next kill to last batch of killed text (@code{append-next-kill}).
@end table

@cindex yanking and text properties
@vindex yank-excluded-properties
  The yank commands discard certain properties from the yanked text.
These are properties that might lead to annoying results, such as
causing the text to respond to the mouse or specifying key bindings.
The list of properties to discard is stored in the variable
@code{yank-excluded-properties}.  These properties are also discarded
when yanking register contents and rectangles.  @xref{Text
Properties,,, elisp, the Emacs Lisp Reference Manual}, for more
information about text properties.

@menu
* Kill Ring::           Where killed text is stored.  Basic yanking.
* Appending Kills::     Several kills in a row all yank together.
* Earlier Kills::       Yanking something killed some time ago.
@end menu

@node Kill Ring
@subsection The Kill Ring

  The @dfn{kill ring} is a list of blocks of text that were previously
killed.  There is only one kill ring, shared by 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.  (There are
several other methods: for instance, you could store the text in a
register; see @ref{Registers}.  @xref{Accumulating Text}, for some
other ways to move text around.)

@kindex C-y
@findex yank
  @kbd{C-y} (@code{yank}) reinserts the text of the most recent kill,
leaving the cursor at the end of the text.  It also adds the position
of the beginning of the text to the mark ring, without activating the
mark; this allows you to jump easily to that position with @kbd{C-x
C-x} (@pxref{Setting Mark}).

  On graphical displays, @kbd{C-y} first checks if another application
has placed any text in the system clipboard more recently than the
last Emacs kill.  If so, it inserts from the clipboard instead of the
kill ring.  Conceptually, you can think of the clipboard as an
``extra'' entry in the kill ring, which is present if you recently cut
or copied some text in another application.  @xref{Cut and Paste}.

  With a plain prefix argument (@kbd{C-u C-y}), the @code{yank}
command instead leaves the cursor in front of the text, and adds the
position of the end of the text to the mark ring.  Using any other
prefix argument specifies an earlier kill; for example, @kbd{C-u 4
C-y} reinserts the fourth most recent kill.  @xref{Earlier Kills}.

@node Appending Kills
@subsection Appending Kills

@cindex appending kills in the ring
  Normally, each kill command pushes a new entry onto the kill ring.
However, two or more kill commands in a row combine their text into a
single entry, so that a single @kbd{C-y} yanks all the text as a unit,
just as it was before it was killed.

  Thus, if you want to yank text as a unit, you need not kill all of it
with 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.

  Commands that kill forward from point add onto the end of the previous
killed text.  Commands that kill backward from point add text 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 text:

@example
This is a line @point{}of sample text.
@end example

@noindent
with point shown by @point{}.  If you type @kbd{M-d M-@key{DEL} M-d
M-@key{DEL}}, killing alternately forward and backward, you end up with
@samp{a line of sample} as one entry in the kill ring, and @samp{This
is@ @ text.} in the buffer.  (Note the double space between @samp{is}
and @samp{text}, which you can clean up with @kbd{M-@key{SPC}} or
@kbd{M-q}.)

  Another way to kill the same text is to move back two words with
@kbd{M-b M-b}, then kill all four words forward with @kbd{C-u M-d}.
This produces exactly the same results in the buffer and in the kill
ring.  @kbd{M-f M-f C-u M-@key{DEL}} kills the same text, all going
backward; once again, the result is the same.  The text in the kill ring
entry always has the same order that it had in the buffer before you
killed it.

@kindex C-M-w
@findex append-next-kill
  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
@kbd{C-M-w} (@code{append-next-kill}) right before it.  The @kbd{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
@kbd{C-M-w}, you can kill several separated pieces of text and
accumulate them to be yanked back in one place.@refill

  A kill command following @kbd{M-w} (@code{kill-ring-save}) does not
append to the text that @kbd{M-w} copied into the kill ring.

@node Earlier Kills
@subsection Yanking Earlier Kills

@cindex yanking previous kills
@kindex M-y
@findex yank-pop
  To recover killed text that is no longer the most recent kill, use the
@kbd{M-y} command (@code{yank-pop}).  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, first use @kbd{C-y} to
yank the last kill, and then use @kbd{M-y} to replace it with the
previous kill.  @kbd{M-y} is allowed only after a @kbd{C-y} or another
@kbd{M-y}.

  You can understand @kbd{M-y} in terms of a ``last yank'' pointer which
points at an entry in the kill ring.  Each time you kill, the ``last
yank'' pointer moves to the newly made entry at the front of the ring.
@kbd{C-y} yanks the entry which the ``last yank'' pointer points to.
@kbd{M-y} moves the ``last yank'' pointer to a different entry, and the
text in the buffer changes to match.  Enough @kbd{M-y} commands can move
the pointer to any entry in the ring, so you can get any entry into the
buffer.  Eventually the pointer reaches the end of the ring; the next
@kbd{M-y} loops back around to the first entry again.

  @kbd{M-y} 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.

  @kbd{M-y} can take a numeric argument, which tells it how many entries
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 ``around'' to the last entry and continues forward from there.

  Once the text you are looking for is brought into the buffer, you can
stop doing @kbd{M-y} commands and it will stay there.  It's just a copy
of the kill ring entry, 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
@kbd{C-y} will yank another copy of the same previous kill.

  If you know how many @kbd{M-y} commands it would take to find the
text you want, you can yank that text in one step using @kbd{C-y} with
a numeric argument.  @kbd{C-y} with an argument restores the text from
the specified kill ring entry, counting back from the most recent as
1.  Thus, @kbd{C-u 2 C-y} gets the next-to-the-last block of killed
text---it is equivalent to @kbd{C-y M-y}.  @kbd{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.

@vindex kill-ring-max
  The length of the kill ring is controlled by the variable
@code{kill-ring-max}; no more than that many blocks of killed text are
saved.

@vindex kill-ring
  The actual contents of the kill ring are stored in a variable named
@code{kill-ring}; you can view the entire contents of the kill ring with
the command @kbd{C-h v kill-ring}.

@node Cut and Paste
@section ``Cut and Paste'' Operations on Graphical Displays
@cindex cut
@cindex copy
@cindex paste

  In most graphical desktop environments, you can transfer data
(usually text) between different applications using a system facility
called the @dfn{clipboard}.  On X, two other similar facilities are
available: the primary selection and the secondary selection.  When
Emacs is run on a graphical display, its kill and yank commands
integrate with these facilities, so that you can easily transfer text
between Emacs and other graphical applications.

  By default, Emacs uses UTF-8 as the coding system for inter-program
text transfers.  If you find that the pasted text is not what you
expected, you can specify another coding system by typing @kbd{C-x
@key{RET} x} or @kbd{C-x @key{RET} X}.  You can also request a
different data type by customizing @code{x-select-request-type}.
@xref{Communication Coding}.

@menu
* Clipboard::           How Emacs uses the system clipboard.
* Primary Selection::   The temporarily selected text selection.
* Secondary Selection:: Cutting without altering point and mark.
@end menu

@node Clipboard
@subsection Using the Clipboard
@cindex clipboard

  The @dfn{clipboard} is the facility that most graphical applications
use for ``cutting and pasting''.  When the clipboard exists, the kill
and yank commands in Emacs make use of it.

  When you kill some text with a command such as @kbd{C-w}
(@code{kill-region}), or copy it to the kill ring with a command such
as @kbd{M-w} (@code{kill-ring-save}), that text is also put in the
clipboard.  @xref{Killing}.

@vindex save-interprogram-paste-before-kill
  When an Emacs kill command puts text in the clipboard, the existing
clipboard contents are normally lost.  Optionally, you can change
@code{save-interprogram-paste-before-kill} to @code{t}.  Then Emacs
will first save the clipboard to its kill ring, preventing you from
losing the old clipboard data---at the risk of high memory consumption
if that data turns out to be large.

  The usual yank commands, such as @kbd{C-y} (@code{yank}), also use
the clipboard.  If another application ``owns'' the clipboard---i.e.,
if you cut or copied text there more recently than your last kill
command in Emacs---then Emacs yanks from the clipboard instead of the
kill ring.  Otherwise, it yanks from the kill ring, as described in
@ref{Yanking}.

@vindex yank-pop-change-selection
  Normally, rotating the kill ring with @kbd{M-y} (@code{yank-pop})
does not alter the clipboard.  However, if you change
@code{yank-pop-change-selection} to @code{t}, then @kbd{M-y} saves the
new yank to the clipboard.

@vindex x-select-enable-clipboard
  To prevent kill and yank commands from accessing the clipboard,
change the variable @code{x-select-enable-clipboard} to @code{nil}.

@vindex x-select-enable-primary
@findex clipboard-kill-region
@findex clipboard-kill-ring-save
@findex clipboard-yank
  Prior to Emacs 24, the kill and yank commands used the primary
selection (@pxref{Primary Selection}), not the clipboard.  If you
prefer this behavior, change @code{x-select-enable-clipboard} to
@code{nil}, @code{x-select-enable-primary} to @code{t}, and
@code{mouse-drag-copy-region} to @code{t}.  In this case, you can use
the following commands to act explicitly on the clipboard:
@code{clipboard-kill-region} kills the region and saves it to the
clipboard; @code{clipboard-kill-ring-save} copies the region to the
kill ring and saves it to the clipboard; and @code{clipboard-yank}
yanks the contents of the clipboard at point.

@node Primary Selection
@subsection Cut and Paste with Other Window Applications
@cindex X cutting and pasting
@cindex X selection
@cindex primary selection
@cindex selection, primary

  Under the X window system, there exists a @dfn{primary selection}
containing the last stretch of text selected in an X application
(usually by dragging the mouse).  Typically, this text can be inserted
into other X applications by @kbd{mouse-2} clicks.  The primary
selection is separate from the clipboard (@pxref{Clipboard}).  Its
contents are more ``fragile''; they are overwritten by any mouse
selection, whereas the clipboard is only overwritten by explicit
``cut'' or ``copy'' commands.

  Under X, whenever you set an active region (@pxref{Mark}), Emacs
saves the text in the active region to the primary selection.  This
applies to active regions made by dragging or clicking the mouse
(@pxref{Mouse Commands}), and those made by keyboard commands (e.g. by
typing @kbd{C-@key{SPC}} and moving point; see @ref{Setting Mark}).

@vindex select-active-regions
  If you change the variable @code{select-active-regions} to
@code{only}, Emacs saves only temporarily active regions to the
primary selection, i.e. those made with the mouse or with shift
selection (@pxref{Shift Selection}).  If you change
@code{select-active-regions} to @code{nil}, Emacs avoids saving active
regions to the primary selection entirely.

  To insert the primary selection into an Emacs buffer, click
@kbd{mouse-2} (@code{mouse-yank-primary}) where you want to insert it.
@xref{Mouse Commands}.

@cindex MS-Windows, and primary selection
  MS-Windows provides no primary selection, but Emacs emulates it
within a single Emacs session by storing the selected text internally.
Therefore, all the features and commands related to the primary
selection work on Windows as they do on X, for cutting and pasting
within the same session, but not across Emacs sessions or with other
applications.

@node Secondary Selection
@subsection Secondary Selection
@cindex secondary selection

  In addition to the primary selection, the X Window System provides a
second similar facility known as the @dfn{secondary selection}.
Nowadays, few X applications make use of the secondary selection, but
you can access it using the following Emacs commands:

@table @kbd
@findex mouse-set-secondary
@kindex M-Drag-Mouse-1
@item M-Drag-Mouse-1
Set the secondary selection, with one end at the place where you press
down the button, and the other end at the place where you release it
(@code{mouse-set-secondary}).  The selected text is highlighted, using
the @code{secondary-selection} face, as you drag.  The window scrolls
automatically if you drag the mouse off the top or bottom of the
window, just like @code{mouse-set-region} (@pxref{Mouse Commands}).

This command does not alter the kill ring.

@findex mouse-start-secondary
@kindex M-Mouse-1
@item M-Mouse-1
Set one endpoint for the @dfn{secondary selection}
(@code{mouse-start-secondary}).

@findex mouse-secondary-save-then-kill
@kindex M-Mouse-3
@item M-Mouse-3
Set the secondary selection, with one end at the position clicked and
the other at the position specified with @kbd{M-Mouse-1}
(@code{mouse-secondary-save-then-kill}).  This also puts the selected
text in the kill ring.  A second @kbd{M-Mouse-3} at the same place
kills the secondary selection just made.

@findex mouse-yank-secondary
@kindex M-Mouse-2
@item M-Mouse-2
Insert the secondary selection where you click, placing point at the
end of the yanked text (@code{mouse-yank-secondary}).
@end table

Double or triple clicking of @kbd{M-Mouse-1} operates on words and
lines, much like @kbd{Mouse-1}.

If @code{mouse-yank-at-point} is non-@code{nil}, @kbd{M-Mouse-2} yanks
at point.  Then it does not matter precisely where you click, or even
which of the frame's windows you click on.  @xref{Mouse Commands}.

@node Accumulating Text
@section Accumulating Text
@findex append-to-buffer
@findex prepend-to-buffer
@findex copy-to-buffer
@findex append-to-file

@cindex accumulating scattered text
  Usually we copy or move text by killing it and yanking it, but there
are other convenient methods for copying one block of text in many
places, or for copying many scattered blocks of text into one place.
Here we describe the commands to accumulate scattered pieces of text
into a buffer or into a file.

@table @kbd
@item M-x append-to-buffer
Append region to the contents of a specified buffer.
@item M-x prepend-to-buffer
Prepend region to the contents of a specified buffer.
@item M-x copy-to-buffer
Copy region into a specified buffer, deleting that buffer's old contents.
@item M-x insert-buffer
Insert the contents of a specified buffer into current buffer at point.
@item M-x append-to-file
Append region to the contents of a specified file, at the end.
@end table

  To accumulate text into a buffer, use @kbd{M-x append-to-buffer}.
This reads a buffer name, then inserts a copy of the region into the
buffer specified.  If you specify a nonexistent buffer,
@code{append-to-buffer} creates the buffer.  The text is inserted
wherever point is in that buffer.  If you have been using the buffer for
editing, the copied text goes into the middle of the text of the buffer,
starting from wherever point happens to be at that moment.

  Point in that buffer is left at the end of the copied text, so
successive uses of @code{append-to-buffer} accumulate the text in the
specified buffer in the same order as they were copied.  Strictly
speaking, @code{append-to-buffer} does not always append to the text
already in the buffer---it appends only if point in that buffer is at the end.
However, if @code{append-to-buffer} is the only command you use to alter
a buffer, then point is always at the end.

  @kbd{M-x prepend-to-buffer} is just like @code{append-to-buffer}
except that point in the other buffer is left before the copied text, so
successive prependings add text in reverse order.  @kbd{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.

  The command @kbd{M-x insert-buffer} can be used to retrieve the
accumulated text from another buffer.  This prompts for the name of a
buffer, and inserts a copy of all the text in that buffer into the
current buffer at point, leaving point at the beginning of the
inserted text.  It also adds the position of the end of the inserted
text to the mark ring, without activating the mark.  @xref{Buffers},
for background information on buffers.

  Instead of accumulating text in a buffer, you can append text
directly into a file with @kbd{M-x append-to-file}.  This prompts for
a filename, and adds the text of the region to the end of the
specified file.  The file is changed immediately on disk.

  You should use @code{append-to-file} only with files that are
@emph{not} being visited in Emacs.  Using it on a file that you are
editing in Emacs would change the file behind Emacs's back, which
can lead to losing some of your editing.

  Another way to move text around is to store it in a register.
@xref{Registers}.

@node Rectangles
@section Rectangles
@cindex rectangle
@cindex columns (and rectangles)
@cindex killing rectangular areas of text

  @dfn{Rectangle} commands operate on rectangular areas of the text:
all the characters between a certain pair of columns, in a certain
range of lines.  Emacs has commands to kill rectangles, yank killed
rectangles, clear them out, fill them with blanks or text, or delete
them.  Rectangle commands are useful with text in multicolumn formats,
and for changing text into or out of such formats.

@cindex mark rectangle
  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 @dfn{region-rectangle} because
you control it in much the same way as the region is controlled.  But
remember that a given combination of point and mark values can be
interpreted either as a region or as a rectangle, depending on the
command that uses them.

  If point and the mark are in the same column, the rectangle they
delimit is empty.  If they are in the same line, the rectangle is one
line high.  This asymmetry between lines and columns comes about
because point (and likewise the mark) is between two columns, but within
a line.

@table @kbd
@item C-x r k
Kill the text of the region-rectangle, saving its contents as the
``last killed rectangle'' (@code{kill-rectangle}).
@item C-x r d
Delete the text of the region-rectangle (@code{delete-rectangle}).
@item C-x r y
Yank the last killed rectangle with its upper left corner at point
(@code{yank-rectangle}).
@item C-x r o
Insert blank space to fill the space of the region-rectangle
(@code{open-rectangle}).  This pushes the previous contents of the
region-rectangle rightward.
@item C-x r c
Clear the region-rectangle by replacing all of its contents with spaces
(@code{clear-rectangle}).
@item M-x delete-whitespace-rectangle
Delete whitespace in each of the lines on the specified rectangle,
starting from the left edge column of the rectangle.
@item C-x r t @var{string} @key{RET}
Replace rectangle contents with @var{string} on each line
(@code{string-rectangle}).
@item M-x string-insert-rectangle @key{RET} @var{string} @key{RET}
Insert @var{string} on each line of the rectangle.
@end table

  The rectangle operations fall into two classes: commands for
deleting and inserting rectangles, and commands for blank rectangles.

@kindex C-x r k
@kindex C-x r d
@findex kill-rectangle
@findex delete-rectangle
  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 @kbd{C-x r d}
(@code{delete-rectangle}) and @kbd{C-x r k} (@code{kill-rectangle}).  In
either case, the portion of each line that falls inside the rectangle's
boundaries is deleted, causing any following text on the line to
move left into the gap.

  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.  It is hard to define yank-popping for rectangles,
so we do not try.

@kindex C-x r y
@findex yank-rectangle
  To yank the last killed rectangle, type @kbd{C-x r y}
(@code{yank-rectangle}).  Yanking a rectangle is the opposite of killing
one.  Point specifies where to put the rectangle's upper left corner.
The rectangle's first line is inserted there, the rectangle's second
line is inserted at the same horizontal position, but one line
vertically down, and so on.  The number of lines affected is determined
by the height of the saved rectangle.

  You can convert single-column lists into double-column lists using
rectangle killing and yanking; kill the second half of the list as a
rectangle and then yank it beside the first line of the list.
@xref{Two-Column}, for another way to edit multi-column text.

  You can also copy rectangles into and out of registers with @kbd{C-x r
r @var{r}} and @kbd{C-x r i @var{r}}.  @xref{Rectangle Registers}.

@kindex C-x r o
@findex open-rectangle
@kindex C-x r c
@findex clear-rectangle
  There are two commands you can use for making blank rectangles:
@kbd{C-x r c} (@code{clear-rectangle}) which blanks out existing text,
and @kbd{C-x r o} (@code{open-rectangle}) which inserts a blank
rectangle.  Clearing a rectangle is equivalent to deleting it and then
inserting a blank rectangle of the same size.

@findex delete-whitespace-rectangle
  The command @kbd{M-x delete-whitespace-rectangle} deletes horizontal
whitespace starting from a particular column.  This applies to each of
the lines in the rectangle, and the column is specified by the left
edge of the rectangle.  The right edge of the rectangle does not make
any difference to this command.

@kindex C-x r t
@findex string-rectangle
  The command @kbd{C-x r t} (@code{string-rectangle}) replaces the
contents of a region-rectangle with a string on each line.  The
string's width need not be the same as the width of the rectangle.  If
the string's width is less, the text after the rectangle shifts left;
if the string is wider than the rectangle, the text after the
rectangle shifts right.

@findex string-insert-rectangle
  The command @kbd{M-x string-insert-rectangle} is similar to
@code{string-rectangle}, but inserts the string on each line,
shifting the original text to the right.

@node CUA Bindings
@section CUA Bindings
@findex cua-mode
@vindex cua-mode
@cindex CUA key bindings
@vindex cua-enable-cua-keys
  The command @kbd{M-x cua-mode} sets up key bindings that are
compatible with the Common User Access (CUA) system used in many other
applications.  @kbd{C-x} means cut (kill), @kbd{C-c} copy, @kbd{C-v}
paste (yank), and @kbd{C-z} undo.  Standard Emacs commands like
@kbd{C-x C-c} still work, because @kbd{C-x} and @kbd{C-c} only take
effect when the mark is active (and the region is highlighted).
However, if you don't want to override these bindings in Emacs at all,
set @code{cua-enable-cua-keys} to @code{nil}.

  To enter an Emacs command like @kbd{C-x C-f} while the mark is
active, use one of the following methods: either hold @kbd{Shift}
together with the prefix key, e.g. @kbd{S-C-x C-f}, or quickly type
the prefix key twice, e.g. @kbd{C-x C-x C-f}.

  In CUA mode, typed text replaces the active region as in
Delete-Selection mode (@pxref{Mouse Commands}).

@cindex rectangle highlighting
  CUA mode provides enhanced rectangle support with visible
rectangle highlighting.  Use @kbd{C-RET} to start a rectangle,
extend it using the movement commands, and cut or copy it using
@kbd{C-x} or @kbd{C-c}.  @kbd{RET} moves the cursor to the next
(clockwise) corner of the rectangle, so you can easily expand it in
any direction.  Normal text you type is inserted to the left or right
of each line in the rectangle (on the same side as the cursor).

  With CUA you can easily copy text and rectangles into and out of
registers by providing a one-digit numeric prefix to the kill, copy,
and yank commands, e.g. @kbd{C-1 C-c} copies the region into register
@code{1}, and @kbd{C-2 C-v} yanks the contents of register @code{2}.

@cindex global mark
  CUA mode also has a global mark feature which allows easy moving and
copying of text between buffers.  Use @kbd{C-S-SPC} to toggle the
global mark on and off.  When the global mark is on, all text that you
kill or copy is automatically inserted at the global mark, and text
you type is inserted at the global mark rather than at the current
position.

  For example, to copy words from various buffers into a word list in
a given buffer, set the global mark in the target buffer, then
navigate to each of the words you want in the list, mark it (e.g. with
@kbd{S-M-f}), copy it to the list with @kbd{C-c} or @kbd{M-w}, and
insert a newline after the word in the target list by pressing
@key{RET}.