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When you edit a file in Emacs, you are actually working on a buffer that is visiting that file—that is, the contents of the file are copied into the buffer and the copy is what you edit. Changes to the buffer do not change the file until you save the buffer, which means copying the contents of the buffer into the file.
This function saves the contents of the current buffer in its visited file if the buffer has been modified since it was last visited or saved. Otherwise it does nothing.
save-buffer is responsible for making backup files. Normally,
backup-option is nil, and save-buffer makes a backup
file only if this is the first save since visiting the file. Other values
for backup-option request the making of backup files in other
circumstances:
save-buffer function marks this version of the file to be backed up
when the buffer is next saved.
save-buffer function unconditionally backs up the previous version of
the file before saving it.
This command saves some modified file-visiting buffers. Normally it asks
the user about each buffer. But if save-silently-p is non-nil,
it saves all the file-visiting buffers without querying the user.
The optional pred argument controls which buffers to ask about (or to
save silently if save-silently-p is non-nil). If it is
nil, that means to ask only about file-visiting buffers. If it is
t, that means also offer to save certain other non-file
buffers—those that have a non-nil buffer-local value of
buffer-offer-save (voir la section Killing Buffers). A user who says
‘yes’ to saving a non-file buffer is asked to specify the file name to
use. The save-buffers-kill-emacs function passes the value t
for pred.
If pred is neither t nor nil, then it should be a
function of no arguments. It will be called in each buffer to decide
whether to offer to save that buffer. If it returns a non-nil value
in a certain buffer, that means do offer to save that buffer.
This function writes the current buffer into file filename, makes the
buffer visit that file, and marks it not modified. Then it renames the
buffer based on filename, appending a string like ‘<2>’ if
necessary to make a unique buffer name. It does most of this work by
calling set-visited-file-name (voir la section Buffer File Name) and
save-buffer.
If confirm is non-nil, that means to ask for confirmation
before overwriting an existing file. Interactively, confirmation is
required, unless the user supplies a prefix argument.
If filename is an existing directory, or a symbolic link to one,
write-file uses the name of the visited file, in directory
filename. If the buffer is not visiting a file, it uses the buffer
name instead.
Saving a buffer runs several hooks. It also performs format conversion (voir la section File Format Conversion), and may save text properties in “annotations” (voir la section Saving Text Properties in Files).
The value of this variable is a list of functions to be called before
writing out a buffer to its visited file. If one of them returns
non-nil, the file is considered already written and the rest of the
functions are not called, nor is the usual code for writing the file
executed.
If a function in write-file-functions returns non-nil, it is
responsible for making a backup file (if that is appropriate). To do so,
execute the following code:
(or buffer-backed-up (backup-buffer)) |
You might wish to save the file modes value returned by backup-buffer
and use that (if non-nil) to set the mode bits of the file that you
write. This is what save-buffer normally does. Voir la section Making Backup Files.
The hook functions in write-file-functions are also responsible for
encoding the data (if desired): they must choose a suitable coding system
and end-of-line conversion (voir la section Coding Systems in Lisp), perform the
encoding (voir la section Explicit Encoding and Decoding), and set last-coding-system-used
to the coding system that was used (voir la section Encoding and I/O).
If you set this hook locally in a buffer, it is assumed to be associated
with the file or the way the contents of the buffer were obtained. Thus the
variable is marked as a permanent local, so that changing the major mode
does not alter a buffer-local value. On the other hand, calling
set-visited-file-name will reset it. If this is not what you want,
you might like to use write-contents-functions instead.
Even though this is not a normal hook, you can use add-hook and
remove-hook to manipulate the list. Voir la section Hooks.
This works just like write-file-functions, but it is intended for
hooks that pertain to the buffer's contents, not to the particular visited
file or its location. Such hooks are usually set up by major modes, as
buffer-local bindings for this variable. This variable automatically
becomes buffer-local whenever it is set; switching to a new major mode
always resets this variable, but calling set-visited-file-name does
not.
If any of the functions in this hook returns non-nil, the file is
considered already written and the rest are not called and neither are the
functions in write-file-functions.
This normal hook runs before a buffer is saved in its visited file, regardless of whether that is done normally or by one of the hooks described above. For instance, the ‘copyright.el’ program uses this hook to make sure the file you are saving has the current year in its copyright notice.
This normal hook runs after a buffer has been saved in its visited file. One use of this hook is in Fast Lock mode; it uses this hook to save the highlighting information in a cache file.
If this variable is non-nil, then save-buffer protects against
I/O errors while saving by writing the new file to a temporary name instead
of the name it is supposed to have, and then renaming it to the intended
name after it is clear there are no errors. This procedure prevents
problems such as a lack of disk space from resulting in an invalid file.
As a side effect, backups are necessarily made by copying. Voir la section Backup by Renaming or by Copying?. Yet, at the same time, saving a precious file always breaks all hard links between the file you save and other file names.
Some modes give this variable a non-nil buffer-local value in
particular buffers.
This variable determines whether files may be written out that do not
end with a newline. If the value of the variable is t, then
save-buffer silently adds a newline at the end of the file whenever
the buffer being saved does not already end in one. If the value of the
variable is non-nil, but not t, then save-buffer asks
the user whether to add a newline each time the case arises.
If the value of the variable is nil, then save-buffer doesn't
add newlines at all. nil is the default value, but a few major modes
set it to t in particular buffers.
See also the function set-visited-file-name (voir la section Buffer File Name).
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Ce document a été généré par Eric Reinbold le 13 Octobre 2007 en utilisant texi2html 1.78.