@c This is part of the Emacs manual.
-@c Copyright (C) 1985, 86, 87, 93, 94, 95, 97, 2000 Free Software Foundation, Inc.
+@c Copyright (C) 1985, 1986, 1987, 1993, 1994, 1995, 1997, 2000, 2001,
+@c 2002, 2003, 2004, 2005, 2006 Free Software Foundation, Inc.
@c See file emacs.texi for copying conditions.
@node Major Modes, Indentation, International, Top
@chapter Major Modes
The least specialized major mode is called @dfn{Fundamental mode}.
This mode has no mode-specific redefinitions or variable settings, so
that each Emacs command behaves in its most general manner, and each
-option is in its default state. For editing text of a specific type
-that Emacs knows about, such as Lisp code or English text, you should
-switch to the appropriate major mode, such as Lisp mode or Text mode.
+user option variable is in its default state. For editing text of a
+specific type that Emacs knows about, such as Lisp code or English
+text, you should switch to the appropriate major mode, such as Lisp
+mode or Text mode.
Selecting a major mode changes the meanings of a few keys to become
more specifically adapted to the language being edited. The ones that
syntactical properties of characters appearing in the buffer.
@xref{Syntax}.
- The major modes fall into three major groups. Lisp mode (which has
-several variants), C mode, Fortran mode and others are for specific
-programming languages. Text mode, Nroff mode, SGML mode, @TeX{} mode
-and Outline mode are for normal text, plain or marked up. The remaining
-major modes are not intended for use on users' files; they are used in
-buffers created for specific purposes by Emacs, such as Dired mode for
-buffers made by Dired (@pxref{Dired}), Mail mode for buffers made by
-@kbd{C-x m} (@pxref{Sending Mail}), and Shell mode for buffers used for
+ The major modes fall into three major groups. The first group
+contains modes for normal text, either plain or with mark-up. It
+includes Text mode, HTML mode, SGML mode, @TeX{} mode and Outline
+mode. The second group contains modes for specific programming
+languages. These include Lisp mode (which has several variants), C
+mode, Fortran mode, and others. The remaining major modes are not
+intended for use on users' files; they are used in buffers created for
+specific purposes by Emacs, such as Dired mode for buffers made by
+Dired (@pxref{Dired}), Mail mode for buffers made by @kbd{C-x m}
+(@pxref{Sending Mail}), and Shell mode for buffers used for
communicating with an inferior shell process (@pxref{Interactive
Shell}).
most of the time Emacs determines which mode to use based on the file
name or on special text in the file.
- Explicit selection of a new major mode is done with a @kbd{M-x} command.
-From the name of a major mode, add @code{-mode} to get the name of a
-command to select that mode. Thus, you can enter Lisp mode by executing
-@kbd{M-x lisp-mode}.
+ To explicitly select a new major, you use an @kbd{M-x} command.
+Take the name of a major mode and add @code{-mode} to get the name of
+the command to select that mode. Thus, you can enter Lisp mode by
+executing @kbd{M-x lisp-mode}.
@vindex auto-mode-alist
When you visit a file, Emacs usually chooses the right major mode based
For example, one element normally found in the list has the form
@code{(@t{"\\.c\\'"} . c-mode)}, and it is responsible for selecting C
mode for files whose names end in @file{.c}. (Note that @samp{\\} is
-needed in Lisp syntax to include a @samp{\} in the string, which is
-needed to suppress the special meaning of @samp{.} in regexps.) If the
-element has the form @code{(@var{regexp} @var{mode-function}
+needed in Lisp syntax to include a @samp{\} in the string, which must
+be used to suppress the special meaning of @samp{.} in regexps.) If
+the element has the form @code{(@var{regexp} @var{mode-function}
@var{flag})} and @var{flag} is non-@code{nil}, then after calling
-@var{mode-function}, the suffix that matched @var{regexp} is discarded
-and the list is searched again for another match.
+@var{mode-function}, Emacs discards the suffix that matched
+@var{regexp} and searches the list again for another match.
- You can specify which major mode should be used for editing a certain
-file by a special sort of text in the first nonblank line of the file. The
+@vindex magic-mode-alist
+ Sometimes the major mode is determined from the way the file's text
+begins. The variable @code{magic-mode-alist} controls this. Its value
+is a list of elements of this form:
+
+@example
+(@var{regexp} . @var{mode-function})
+@end example
+
+@noindent
+This looks like an element of @code{auto-mode-alist}, but it doesn't work
+the same: this @var{regexp} is matched against the text at the start
+of the buffer, not against the file name. @code{magic-mode-alist}
+takes priority over @code{auto-mode-alist}.
+
+ You can specify the major mode to use for editing a certain file by
+special text in the first nonblank line of the file. The
mode name should appear in this line both preceded and followed by
@samp{-*-}. Other text may appear on the line as well. For example,
@noindent
tells Emacs to use Lisp mode. Such an explicit specification overrides
-any defaulting based on the file name. Note how the semicolon is used
+any defaults based on the file name. Note how the semicolon is used
to make Lisp treat this line as a comment.
Another format of mode specification is
mode Emacs would choose automatically: use the command @kbd{M-x
normal-mode} to do this. This is the same function that
@code{find-file} calls to choose the major mode. It also processes
-the file's local variables list if any.
+the file's @samp{-*-} line or local variables list (if any).
+@xref{File Variables}.
@vindex change-major-mode-with-file-name
The commands @kbd{C-x C-w} and @code{set-visited-file-name} change to
a new major mode if the new file name implies a mode (@pxref{Saving}).
+(@kbd{C-x C-s} does this too, if the buffer wasn't visiting a file.)
However, this does not happen if the buffer contents specify a major
mode, and certain ``special'' major modes do not allow the mode to
change. You can turn off this mode-changing feature by setting
@code{change-major-mode-with-file-name} to @code{nil}.
+
+@ignore
+ arch-tag: f2558800-cf32-4839-8acb-7d3b4df2a155
+@end ignore