23.2 Visiting Files
- C-x C-f
- Visit a file (
find-file
).
- C-x C-r
- Visit a file for viewing, without allowing changes to it
(
find-file-read-only
).
- C-x C-v
- Visit a different file instead of the one visited last
(
find-alternate-file
).
- C-x 4 f
- Visit a file, in another window (
find-file-other-window
). Don't
alter what is displayed in the selected window.
- C-x 5 f
- Visit a file, in a new frame (
find-file-other-frame
). Don't
alter what is displayed in the selected frame.
- M-x find-file-literally
- Visit a file with no conversion of the contents.
Visiting a file means copying its contents into an Emacs
buffer so you can edit them. Emacs makes a new buffer for each file
that you visit. We often say that this buffer “is visiting” that
file, or that the buffer's “visited file” is that file. Emacs
constructs the buffer name from the file name by throwing away the
directory, keeping just the name proper. For example, a file named
/usr/rms/emacs.tex would get a buffer named ‘emacs.tex’.
If there is already a buffer with that name, Emacs constructs a unique
name—the normal method is to append ‘<2>’, ‘<3>’, and so
on, but you can select other methods (see Uniquify).
Each window's mode line shows the name of the buffer that is being displayed
in that window, so you can always tell what buffer you are editing.
The changes you make with editing commands are made in the Emacs
buffer. They do not take effect in the file that you visited, or any
place permanent, until you save the buffer. Saving the buffer
means that Emacs writes the current contents of the buffer into its
visited file. See Saving.
If a buffer contains changes that have not been saved, we say the
buffer is modified. This is important because it implies that
some changes will be lost if the buffer is not saved. The mode line
displays two stars near the left margin to indicate that the buffer is
modified.
To visit a file, use the command C-x C-f (find-file
). Follow
the command with the name of the file you wish to visit, terminated by a
<RET>.
The file name is read using the minibuffer (see Minibuffer), with
defaulting and completion in the standard manner (see File Names).
While in the minibuffer, you can abort C-x C-f by typing
C-g. File-name completion ignores certain filenames; for more
about this, see Completion Options.
Your confirmation that C-x C-f has completed successfully is the
appearance of new text on the screen and a new buffer name in the mode
line. If the specified file does not exist and could not be created, or
cannot be read, then you get an error, with an error message displayed
in the echo area.
If you visit a file that is already in Emacs, C-x C-f does not make
another copy. It selects the existing buffer containing that file.
However, before doing so, it checks that the file itself has not changed
since you visited or saved it last. If the file has changed, a warning
message is shown. See Simultaneous Editing.
If you try to visit a file larger than
large-file-warning-threshold
(the default is 10000000, which is
about 10 megabytes), Emacs will ask you for confirmation first. You
can answer y to proceed with visiting the file. Note, however,
that Emacs cannot visit files that are larger than the maximum Emacs
buffer size, which is around 256 megabytes on 32-bit machines
(see Buffers). If you try, Emacs will display an error message
saying that the maximum buffer size has been exceeded.
On graphical terminals, there are two additional methods for
visiting files. Firstly, when Emacs is built with a suitable GUI
toolkit, commands invoked with the mouse (by clicking on the menu bar
or tool bar) use the toolkit's standard File Selection dialog instead
of prompting for the file name in the minibuffer. On Unix and
GNU/Linux platforms, Emacs does that when built with GTK, LessTif, and
Motif toolkits; on MS-Windows, the GUI version does that by default.
For information on how to customize this, see Dialog Boxes.
Secondly, Emacs supports the “drag and drop” protocol on the X
window system. Dropping a file into an ordinary Emacs window visits
the file using that window. However, dropping a file into a window
displaying a Dired buffer moves or copies the file into the displayed
directory. For details, see Drag and Drop, Misc Dired Features.
What if you want to create a new file? Just visit it. Emacs displays
‘(New file)’ in the echo area, but in other respects behaves as if
you had visited an existing empty file. If you make any changes and
save them, the file is created.
Emacs recognizes from the contents of a file which convention it uses
to separate lines—newline (used on GNU/Linux and on Unix),
carriage-return linefeed (used on Microsoft systems), or just
carriage-return (used on the Macintosh)—and automatically converts the
contents to the normal Emacs convention, which is that the newline
character separates lines. This is a part of the general feature of
coding system conversion (see Coding Systems), and makes it possible
to edit files imported from different operating systems with
equal convenience. If you change the text and save the file, Emacs
performs the inverse conversion, changing newlines back into
carriage-return linefeed or just carriage-return if appropriate.
If the file you specify is actually a directory, C-x C-f invokes
Dired, the Emacs directory browser, so that you can “edit” the contents
of the directory (see Dired). Dired is a convenient way to view, delete,
or operate on the files in the directory. However, if the variable
find-file-run-dired
is nil
, then it is an error to try
to visit a directory.
Files which are actually collections of other files, or file
archives, are visited in special modes which invoke a Dired-like
environment to allow operations on archive members. See File Archives, for more about these features.
If the file name you specify contains shell-style wildcard
characters, Emacs visits all the files that match it. Wildcards
include ‘?’, ‘*’, and ‘[...]’ sequences. To enter
the wild card ‘?’ in a file name in the minibuffer, you need to
type C-q ?. See Quoted File Names, for information on how to
visit a file whose name actually contains wildcard characters. You
can disable the wildcard feature by customizing
find-file-wildcards
.
If you visit a file that the operating system won't let you modify,
or that is marked read-only, Emacs makes the buffer read-only too, so
that you won't go ahead and make changes that you'll have trouble
saving afterward. You can make the buffer writable with C-x C-q
(toggle-read-only
). See Misc Buffer.
If you want to visit a file as read-only in order to protect
yourself from entering changes accidentally, visit it with the command
C-x C-r (find-file-read-only
) instead of C-x C-f.
If you visit a nonexistent file unintentionally (because you typed the
wrong file name), use the C-x C-v command
(find-alternate-file
) to visit the file you really wanted.
C-x C-v is similar to C-x C-f, but it kills the current
buffer (after first offering to save it if it is modified). When
C-x C-v reads the file name to visit, it inserts the entire
default file name in the buffer, with point just after the directory
part; this is convenient if you made a slight error in typing the name.
If you find a file which exists but cannot be read, C-x C-f
signals an error.
C-x 4 f (find-file-other-window
) is like C-x C-f
except that the buffer containing the specified file is selected in another
window. The window that was selected before C-x 4 f continues to
show the same buffer it was already showing. If this command is used when
only one window is being displayed, that window is split in two, with one
window showing the same buffer as before, and the other one showing the
newly requested file. See Windows.
C-x 5 f (find-file-other-frame
) is similar, but opens a
new frame, or makes visible any existing frame showing the file you
seek. This feature is available only when you are using a window
system. See Frames.
If you wish to edit a file as a sequence of ASCII characters with no special
encoding or conversion, use the M-x find-file-literally command.
It visits a file, like C-x C-f, but does not do format conversion
(see Formatted Text), character code conversion (see Coding Systems), or automatic uncompression (see Compressed Files), and
does not add a final newline because of require-final-newline
.
If you already have visited the same file in the usual (non-literal)
manner, this command asks you whether to visit it literally instead.
Two special hook variables allow extensions to modify the operation of
visiting files. Visiting a file that does not exist runs the functions
in the list find-file-not-found-functions
; this variable holds a list
of functions, and the functions are called one by one (with no
arguments) until one of them returns non-nil
. This is not a
normal hook, and the name ends in ‘-functions’ rather than ‘-hook’
to indicate that fact.
Successful visiting of any file, whether existing or not, calls the
functions in the list find-file-hook
, with no arguments.
This variable is a normal hook. In the case of a nonexistent file, the
find-file-not-found-functions
are run first. See Hooks.
There are several ways to specify automatically the major mode for
editing the file (see Choosing Modes), and to specify local
variables defined for that file (see File Variables).