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Emacs registers are places you can save text or positions for
later use. Text and rectangles saved in registers can be copied into
the buffer once or many times; you can move point to a position saved in
a register.
Each register has a name which is a single character. A register can store a piece of text, a rectangle, a position, a window configuration or a file name, but only one thing at any given time. Whatever you store in a register remains there until you store something else in that register. To see what a register r contains, use M-x view-register.
Saving a position records a spot in a buffer so that you can move back there later. Moving to a saved position reselects that buffer and moves point to that spot.
point-to-register).
jump-to-register).
To save the current position of point in a register, choose a name
r and type C-x r SPC r. The register r
retains the position thus saved until you store something else in that
register.
The command C-x r j r moves point to the position recorded in register r. The register is not affected; it continues to record the same position. You can jump to the same position using the same register any number of times.
When you want to insert a copy of the same piece of text several times, it may be inconvenient to yank it from the kill ring, since each subsequent kill moves that entry further down the ring. An alternative is to store the text in a register and later retrieve it.
copy-to-register).
insert-register).
C-x r s r stores a copy of the text of the region into the register named r. Given a numeric argument, C-x r s r deletes the text from the buffer as well.
C-x r i r inserts in the buffer the text from register r. Normally it leaves point before the text and places the mark after, but with a numeric argument (C-u) it puts point after the text and the mark before.
A register can contain a rectangle instead of linear text. The rectangle is represented as a list of strings. See section Rectangles, for basic information on how to specify a rectangle in the buffer.
copy-region-to-rectangle). With numeric argument, delete it as
well.
insert-register).
The C-x r i r command inserts a text string if the register contains one, and inserts a rectangle if the register contains one.
You can save the window configuration of the selected frame in a register, or even the configuration of all frames, and restore the configuration later.
window-configuration-to-register).
frame-configuration-to-register).
Use C-x r j r to restore a window or frame configuration. This is the same command used to restore a cursor position. When you restore a frame configuration, any existing frames not included in the configuration become invisible. If you wish to delete these frames instead, use C-u C-x r j r.
If you visit certain file names frequently, you can visit them more conveniently if you put their names in registers. Here's the Lisp code used to put a file name in a register:
(set-register ?r '(file . name))
For example,
(set-register ?z '(file . "/gd/gnu/emacs/19.0/src/ChangeLog"))
puts the file name shown in register `z'.
To visit the file whose name is in register r, type C-x r j r. (This is the same command used to jump to a position or restore a frame configuration.)
Bookmarks are somewhat like registers in that they record positions you can jump to. Unlike registers, they have long names, and they persist automatically from one Emacs session to the next. The prototypical use of bookmarks is to record "where you were reading" in various files.
bookmark-set).
bookmark-jump).
list-bookmarks.
The prototypical use for bookmarks is to record one current position
in each of several files. So the command C-x r m, which sets a
bookmark, uses the visited file name as the default for the bookmark
name. If you name each bookmark after the file it points to, then you
can conveniently revisit any of those files with C-x r b, and move
to the position of the bookmark at the same time.
To display a list of all your bookmarks in a separate buffer, type
C-x r l (list-bookmarks). If you switch to that buffer,
you can use it to edit your bookmark definitions. Type C-h m in
that buffer for more information about its special editing commands.
When you kill Emacs, Emacs offers to save your bookmark values in your
default bookmark file, `~/.emacs-bkmrks', if you have changed any
bookmark values. You can also save the bookmarks at any time with the
M-x bookmark-save command. The bookmark commands load your
default bookmark file automatically. This saving and loading is how
bookmarks persist from one Emacs session to the next.
If you set the variable bookmark-save-flag to 1, then each
command that sets a bookmark will also save your bookmarks; this way,
you don't lose any bookmark values even if Emacs crashes.
Bookmark position values are saved with surrounding context, so that
bookmark-jump can find the proper position even if the file is
modified slightly. The variable bookmark-search-size says how
many characters of context to record, on each side of the bookmark's
position.
Here are some additional commands for working with bookmarks:
bookmark-write, to
work with other files of bookmark values in addition to your default
bookmark file.
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