tutorial

早期freebsd实现

MODE LINE
---------

If Emacs sees that you are typing commands slowly it shows them to you
at the bottom of the screen in an area called the "echo area."  The echo
area contains the bottom line of the screen.  The line immediately above
it is called the MODE LINE.  The mode line says something like

--**--Emacs: TUTORIAL		    (Fundamental)----58%-------------

This is a very useful "information" line.

You already know what the filename means--it is the file you have
found.  What the --NN%-- means is that NN percent of the file is
above the top of the screen.  If the top of the file is on the screen,
it will say --TOP-- instead of --00%--.  If the bottom of the file is
on the screen, it will say --BOT--.  If you are looking at a file so
small it all fits on the screen, it says --ALL--.

The stars near the front mean that you have made changes to the text.
Right after you visit or save a file, there are no stars, just dashes.

The part of the mode line inside the parentheses is to tell you what
modes you are in.  The default mode is Fundamental which is what you
are in now.  It is an example of a "major mode".  There are several
major modes in Emacs for editing different languages and text, such as
Lisp mode, Text mode, etc.  At any time one and only one major mode is
active, and its name can always be found in the mode line just where
"Fundamental" is now.  Each major mode makes a few commands behave
differently.  For example, there are commands for creating comments in
a program, and since each programming language has a different idea of
what a comment should look like, each major mode has to insert
comments differently.  Each major mode is the name of an extended
command, which is how you get into the mode.  For example,
M-X fundamental-mode is how to get into Fundamental mode.

If you are going to be editing English text, such as this file, you
should probably use Text Mode.
>> Type M-x text-mode<Return>.

Don't worry, none of the commands you have learned changes Emacs in
any great way.  But you can now observe that periods are no longer
part of words when you do M-f or M-b!  Major modes are usually like
that: commands don't change into completely unrelated things, but they
work a little bit differently.

To get documentation on your current major mode, type C-h m.

>> Use C-u C-v once or more to bring this line near the top of screen.
>> Type C-h m, to see how Text mode differs from Fundamental mode.
>> Type C-x 1 to remove the documentation from the screen.

Major modes are called major because there are also minor modes.
They are called minor because they aren't alternatives to the major
modes, just minor modifications of them.  Each minor mode can be
turned on or off by itself, regardless of what major mode you are in,
and regardless of the other minor modes.  So you can use no minor
modes, or one minor mode, or any combination of several minor modes.

One minor mode which is very useful, especially for editing English
text, is Auto Fill mode.  When this mode is on, Emacs breaks the line
in between words automatically whenever the line gets too long.  You
can turn this mode on by doing M-x auto-fill-mode<Return>.  When the
mode is on, you can turn it off by doing M-x auto-fill-mode<Return>.
If the mode is off, this function turns it on, and if the mode is on,
this function turns it off.  This is called "toggling".

>> Type M-x auto-fill-mode<Return> now.  Then insert a line of "asdf "
   over again until you see it divide into two lines.  You must put in
   spaces between them because Auto Fill breaks lines only at spaces.

The margin is usually set at 70 characters, but you can change it
with the C-x f command.  You should give the margin setting you want
as a numeric argument.

>> Type C-x f with an argument of 20.  (C-u 2 0 C-x f).
   Then type in some text and see Emacs fill lines of 20
   characters with it.  Then set the margin back to 70 using
   C-x f again.

If you makes changes in the middle of a paragraph, Auto Fill mode
does not re-fill it for you.
To re-fill the paragraph, type M-q (Meta-q) with the cursor inside
that paragraph.

>> Move the cursor into the previous paragraph and type M-q.

SEARCHING
---------

Emacs can do searches for strings (these are groups of contiguous
characters or words) either forward through the file or backward
through it.  To search for the string means that you are trying to
locate it somewhere in the file and have Emacs show you where the
occurrences of the string exist.  This type of search is somewhat
different from what you may be familiar with.  It is a search that is
performed as you type in the thing to search for.  The command to
initiate a search is C-s for forward search, and C-r for reverse
search.  BUT WAIT!  Don't do them now.  When you type C-s you'll
notice that the string "I-search" appears as a prompt in the echo
area.  This tells you that Emacs is in what is called an incremental
search waiting for you to type the thing that you want to search for.
<ESC> terminates a search.

>> Now type C-s to start a search.  SLOWLY, one letter at a time,
   type the word 'cursor', pausing after you type each
   character to notice what happens to the cursor.
>> Type C-s to find the next occurrence of "cursor".
>> Now type <Rubout> four times and see how the cursor moves.
>> Type <ESC> to terminate the search.

Did you see what happened?  Emacs, in an incremental search, tries to
go to the occurrence of the string that you've typed out so far.  To go
to the next occurrence of 'cursor' just type C-s again.  If no such
occurrence exists Emacs beeps and tells you that it is a failing
search.  C-g would also terminate the search.

If you are in the middle of an incremental search and type <Rubout>,
you'll notice that the last character in the search string is erased
and the search backs up to the last place of the search.  For
instance, suppose you currently have typed 'cu' and you see that your
cursor is at the first occurrence of 'cu'.  If you now type <Rubout>,
the 'u' on the search line is erased and you'll be repositioned in the
text to the occurrence of 'c' where the search took you before you
typed the 'u'.  This provides a useful means for backing up while you
are searching.

If you are in the middle of a search and happen to type a control
character (other than a C-s or C-r, which tell Emacs to search for the
next occurrence of the string), the search is terminated.

The C-s starts a search that looks for any occurrence of the search
string AFTER the current cursor position.  But what if you want to
search for something earlier in the text?  To do this, type C-r for
Reverse search.  Everything that applies to C-s applies to C-r except
that the direction of the search is reversed.


RECURSIVE EDITING LEVELS
------------------------

Sometimes you will get into what is called a "recursive editing
level".  This is indicated by square brackets in the mode line,
surrounding the parentheses around the major mode name.  For
example, you might see [(Fundamental)] instead of (Fundamental).

To get out of the recursive editing level, type
  M-x top-level<Return>.

>> Try that now; it should display "Back to top level"
   at the bottom of the screen.

In fact, you were ALREADY at top level (not inside a recursive editing
level) if you have obeyed instructions.  M-x top-level does not care;
it gets out of any number of recursive editing levels, perhaps zero,
to get back to top level.

You can't use C-g to get out of a recursive editing level because C-g
is used for discarding numeric arguments and partially typed commands
WITHIN the recursive editing level.


GETTING MORE HELP
-----------------

In this tutorial we have tried to supply just enough information to
get you started using Emacs.  There is so much available in Emacs that
it would be impossible to explain it all here.  However, you may want
to learn more about Emacs since it has numerous desirable features
that you don't know about yet.  Emacs has a great deal of internal
documentation.  All of these commands can be accessed through
the character Control-h, which we call "the Help character"
because of the function it serves.

To use the HELP features, type the C-h character, and then a
character saying what kind of help you want.  If you are REALLY lost,
type C-h ? and Emacs will tell you what kinds of help it can give.
If you have typed C-h and decide you don't want any help, just
type C-G to cancel it.

The most basic HELP feature is C-h c.  Type C-h, a c, and a
command character or sequence, and Emacs displays a very brief
description of the command.

>> Type C-h c Control-p.
  The message should be something like

	C-p runs the command previous-line

This tells you the "name of the function".  That is important in
writing Lisp code to extend Emacs; it also is enough to remind
you of what the command does if you have seen it before but did
not remember.

Multi-character commands such as C-x C-s and (if you have no META or
EDIT key) <ESC>v are also allowed after C-h c.

To get more information on the command, use C-h k instead of C-h c.

>> Type C-h k Control-p.

This displays the documentation of the function, as well as its name,
in an Emacs window.  When you are finished reading the output, type
C-x 1 to get rid of the help text.  You do not have to do this right
away.  You can do some editing based on the help text before you type
C-x 1.

Here are some other useful C-h options:

   C-h f	Describe a function.  You type in the name of the
		function.

>> Try typing C-h f previous-line<Return>.
   This prints all the information Emacs has about the
   function which implements the C-P command.

   C-h a	Command Apropos.  Type in a keyword and Emacs will list
		all the commands whose names contain that keyword.
		These commands can all be invoked with Meta-x.
		For some commands, Command Apropos will also list a one
		or two character sequence which has the same effect.

>> Type C-h a file<Return>.  You will see a list of all M-x commands
with "file" in their names.  You will also see commands
like C-x C-f and C-x C-w, listed beside the command names
find-file and write-file.


CONCLUSION
----------

Remember, to exit Emacs permanently use C-x C-c.  To exit to a shell
temporarily, so that you can come back in, use C-z.

This tutorial is meant to be understandable to all new users, so if
you found something unclear, don't sit and blame yourself - complain!


COPYING
-------

This tutorial descends from a long line of Emacs tutorials
starting with the one written by Stuart Cracraft for the original Emacs.

This version of the tutorial, like GNU Emacs, is copyrighted, and
comes with permission to distribute copies on certain conditions:

Copyright (c) 1985 Free Software Foundation

   Permission is granted to anyone to make or distribute verbatim copies
   of this document as received, in any medium, provided that the
   copyright notice and permission notice are preserved,
   and that the distributor grants the recipient permission
   for further redistribution as permitted by this notice.

   Permission is granted to distribute modified versions
   of this document, or of portions of it,
   under the above conditions, provided also that they
   carry prominent notices stating who last altered them.

The conditions for copying Emacs itself are slightly different
but in the same spirit.  Please read the file COPYING and then
do give copies of GNU Emacs to your friends.
Help stamp out software obstructionism ("ownership") by using,
writing, and sharing free software!