N.6 Indirect Buffers

An indirect buffer shares the text of some other buffer, which is called the base buffer of the indirect buffer. In some ways it is the analogue, for buffers, of a symbolic link between files.

M-x make-indirect-buffer RET base-buffer RET indirect-name RET

Create an indirect buffer named indirect-name whose base buffer is base-buffer.

M-x clone-indirect-buffer RET

Create an indirect buffer that is a twin copy of the current buffer.

C-x 4 c

Create an indirect buffer that is a twin copy of the current buffer, and select it in another window (clone-indirect-buffer-other-window).

The text of the indirect buffer is always identical to the text of its base buffer; changes made by editing either one are visible immediately in the other. But in all other respects, the indirect buffer and its base buffer are completely separate. They have different names, different values of point, different narrowing, different markers, different major modes, and different local variables.

An indirect buffer cannot visit a file, but its base buffer can. If you try to save the indirect buffer, that actually works by saving the base buffer. Killing the base buffer effectively kills the indirect buffer, but killing an indirect buffer has no effect on its base buffer.

One way to use indirect buffers is to display multiple views of an outline. See section T.8.4 Viewing One Outline in Multiple Views.

A quick and handy way to make an indirect buffer is with the command M-x clone-indirect-buffer. It creates and selects an indirect buffer whose base buffer is the current buffer. With a numeric argument, it prompts for the name of the indirect buffer; otherwise it defaults to the name of the current buffer, modifying it by adding a `<n>' prefix if required. C-x 4 c (clone-indirect-buffer-other-window) works like M-x clone-indirect-buffer, but it selects the cloned buffer in another window. These commands come in handy if you want to create new `*info*' or `*Help*' buffers, for example.

The more general way is with the command M-x make-indirect-buffer. It creates an indirect buffer from buffer base-buffer, under the name indirect-name. It prompts for both base-buffer and indirect-name using the minibuffer.