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:ID:       c7747161-284c-4882-bd11-80bc2a990814
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#+title:  buffer

An [[id:5f1df0e1-384f-4685-ae1e-fec2431b04e5][emacs]] buffer is similar to what other systems might call a file, document, workspace or editor. A buffer can contain text and images.

Buffers are shown in [[id:216bfc04-0276-4c4b-8ec7-0b7d16bc62cc][emacs-window]] on the screen. A buffer can be displayed in more than one window at a time, or it might not be displayed at all.

At the bottom of each window is a ModeLine that describes the buffer and its state. Every buffer has a unique buffer name; the name is shown in the mode-line.

By default, visiting a file puts the file content into a buffer and displays it in a window. By default, the buffer name is based on the (relative) file name.

Saving a buffer writes it to its visited file.

Killing a buffer discards its contents. By default, Emacs prompts you if there are unsaved changes.

By convention, buffers whose names start with an asterisk (*) are not associated with files. For example, by default Emacs starts with an empty buffer named *scratch*. If such buffers have unsaved changes when you exit Emacs, these buffers are discarded without asking.

Buffers whose names start with a space are invisible, which means they are hidden from many operations. These buffers are typically created and used by Emacs for internal purposes.

* Buffer Commands and Their Keys
| Key     | Meaning                                                          | Command             |
|---------+------------------------------------------------------------------+---------------------|
| C-x C-f | Find and visit a file                                            | find-file           |
| C-x C-r | Visit a file in read-only mode                                   | find-file-read-only |
| C-x C-s | Save the current buffer to its file                              | save-buffer         |
| C-x C-w | Save the current buffer contents to a file you specify (Save As) | write-file          |
| C-x k   | Kill a buffer you name                                           | kill-buffer         |
| C-x b   | Switch to editing a buffer you specify                           | switch-to-buffer    |
| C-x C-b | Open the BufferMenu                                              | list-buffers        |
|         |                                                                  |                     |