e Tutorial

e is a minimal Emacs-like text editor. The commands are generally
the same as Emacs's, although many Emacs commands are not implemented
by e.

e commands generally involve the CONTROL key (sometimes labeled
CTRL or CTL) or the META key (sometimes labeled EDIT or ALT). Rather than
write that in full each time, we'll use the following abbreviations:

 C-<chr>  means hold the CONTROL key while typing the character <chr>
	  Thus, C-f would be: hold the CONTROL key and type f.
 M-<chr>  means hold the META or EDIT or ALT key down while typing <chr>.
	  If there is no META, EDIT or ALT key, instead press and release the
	  ESC key and then type <chr>. We write <ESC> for the ESC key.

Important note: to end the e session, type C-x C-c. (Two characters.)
To quit a partially entered command, type C-g.
The characters ">>" at the left margin indicate directions for you to
try using a command. For instance:





[Middle of page left blank for didactic purposes. Text continues below]





>>  Now type C-v (View next screen) to move to the next screen.
	(go ahead, do it by holding down the CONTROL key while typing v).
	From now on, you should do this again whenever you finish
	reading the screen.

Note that there is an overlap of two lines when you move from screen
to screen; this provides some continuity so you can continue reading
the text.

The first thing that you need to know is how to move around from place
to place in the text. You already know how to move forward one screen,
with C-v. To move backwards one screen, type M-v (hold down the META key
and type v, or type <ESC>v if you do not have a META, EDIT, or ALT key).

>>  Try typing M-v and then C-v, a few times.


SUMMARY
-------

The following commands are useful for viewing screenfuls:

	C-v	Move forward one screenful
	M-v	Move backward one screenful
	C-l	Clear screen and redisplay all the text
		 (That's CONTROL-L, not CONTROL-1.)

You can also use the PageUp and PageDn keys to move by screenfuls, if
your terminal has them, but you can edit more efficiently if you use
C-v and M-v.


BASIC CURSOR CONTROL
--------------------

Moving from screenful to screenful is useful, but how do you
move to a specific place within the text on the screen?

There are several ways you can do this. You can use the arrow keys,
but it's more efficient to keep your hands in the standard position
and use the commands C-p, C-b, C-f, and C-n. These characters
are equivalent to the four arrow keys, like this:

			  Previous line, C-p
				  :
				  :
   Backward, C-b .... Current cursor position .... Forward, C-f
				  :
				  :
			    Next line, C-n

>> Move the cursor to the line in the middle of that diagram
   using C-n or C-p. Then type C-l to see the whole diagram
   centered in the screen.

You'll find it easy to remember these letters by words they stand for:
P for previous, N for next, B for backward and F for forward. You
will be using these basic cursor positioning commands all the time.

>> Do a few C-n's to bring the cursor down to this line.

>> Move into the line with C-f's and then up with C-p's.
   See what C-p does when the cursor is in the middle of the line.

Each line of text ends with a Newline character, which serves to
separate it from the following line. (Normally, the last line in
a file will have a Newline at the end, but e does not require it.)

>> Try to C-b at the beginning of a line. It should move to
   the end of the previous line. This is because it moves back
   across the Newline character.

C-f can move across a Newline just like C-b.

>> Do a few more C-b's, so you get a feel for where the cursor is.
   Then do C-f's to return to the end of the line.
   Then do one more C-f to move to the following line.

When you move past the top or bottom of the screen, the text beyond
the edge shifts onto the screen. This is called "scrolling". It
enables e to move the cursor to the specified place in the text
without moving it off the screen.

>> Try to move the cursor off the bottom of the screen with C-n, and
   see what happens.

If moving by characters is too slow, you can move by words. M-f
(META-f) moves forward a word and M-b moves back a word.

>> Type a few M-f's and M-b's.

When you are in the middle of a word, M-f moves to the end of the word.
When you are in whitespace between words, M-f moves to the end of the
following word. M-b works likewise in the opposite direction.

>> Type M-f and M-b a few times, interspersed with C-f's and C-b's
   so that you can observe the action of M-f and M-b from various
   places inside and between words.

Notice the parallel between C-f and C-b on the one hand, and M-f and
M-b on the other hand. Very often Meta characters are used for
operations related to the units defined by language (words, sentences,
paragraphs), while Control characters operate on basic units that are
independent of what you are editing (characters, lines, etc).

This parallel applies between lines and sentences: C-a and C-e move to
the beginning or end of a line, and M-a and M-e move to the beginning
or end of a sentence.

>> Try a couple of C-a's, and then a couple of C-e's.
   Try a couple of M-a's, and then a couple of M-e's.

See how repeated C-a's do nothing, but repeated M-a's keep moving one
more sentence. Although these are not quite analogous, each one seems
natural.

The location of the cursor in the text is also called "point". To
paraphrase, the cursor shows on the screen where point is located in
the text.

Here is a summary of simple cursor-moving operations, including the
word and sentence moving commands:

	C-f	Move forward a character
	C-b	Move backward a character

	M-f	Move forward a word
	M-b	Move backward a word

	C-n	Move to next line
	C-p	Move to previous line

	C-a	Move to beginning of line
	C-e	Move to end of line

	M-a	Move back to beginning of sentence
	M-e	Move forward to end of sentence

>> Try all of these commands now a few times for practice.
   These are the most often used commands.

Two other important cursor motion commands are M-< (META Less-than),
which moves to the beginning of the whole text, and M-> (META
Greater-than), which moves to the end of the whole text.

On most terminals, the "<" is above the comma and ">" is above the
period, so you must use the shift key to type them. On these terminals
you must use the shift key to type M-< and M-> also; without the shift
key, you would be typing M-comma or M-period.

>> Try M-< now, to move to the beginning of the tutorial.
   Then use C-v repeatedly to move back here.

>> Try M-> now, to move to the end of the tutorial.
   Then use M-v repeatedly to move back here.

You can also move the cursor with the arrow keys, if your terminal has
arrow keys. We recommend learning C-b, C-f, C-n and C-p for three
reasons. First, they work on all kinds of terminals. Second, once
you gain practice at using e, you will find that typing these Control
characters is faster than typing the arrow keys (because you do not
have to move your hands away from touch-typing position). Third, once
you form the habit of using these Control character commands, you can
easily learn to use other advanced cursor motion commands as well.


THE UNIVERSAL ARGUMENT
----------------------

Most e commands accept a numeric argument; for most commands, this
serves as a repeat count. The way you give a command a repeat count
is by typing C-u and then the digits before you type the command. If
you have a META (or EDIT or ALT) key, there is another, alternative way
to enter a numeric argument: type the digits while holding down the
META key. We recommend learning the C-u method because it works on
any terminal. The numeric argument is also called a "prefix argument",
because you type the argument before the command it applies to.

For instance, C-u 8 C-f moves forward eight characters.

>> Try using C-n or C-p with a numeric argument, to move the cursor
   to a line near this one with just one command.

Most commands use the numeric argument as a repeat count, but some
commands use it in some other way. Several commands (but none of
those you have learned so far) use it as a flag - the presence of a
prefix argument, regardless of its value, makes the command do
something different.

C-v and M-v are another kind of exception. When given an argument,
they scroll the screen up or down by that many lines, rather than by a
screenful. For example, C-u 8 C-v scrolls the screen by 8 lines.

>> Try typing C-u 8 C-v now.

This should have scrolled the screen up by 8 lines. If you would like
to scroll it down again, you can give an argument to M-v.


THE GOTO COMMAND
----------------

Now that we've learned about the universal argument, we can introduce
another cursor positioning command, the command to move to a specific
line. This command is given by giving a line number via the universal
argument, and then typing M-g.

>> Try using a M-< or M-> command to move to the beginning or the
   end of the file. Then come back here using the M-G command (this
   is line 241, so you'd type C-u 241 M-g.)


CANCELLING COMMANDS
-------------------

If you get partway through entering a command and decide you
want to stop, you can always cancel it by typing C-g. For example,
if you start to enter a numeric argument but you make a typo and
it is too large, you can discard it with a C-g.

>> Type C-u 100 to make a numeric argument of 100, then type C-g.
   Now type C-f. It should move just one character, because you
   canceled the argument with C-g.

If you have typed an <ESC> by mistake, you can get rid of it with a C-g.


ERRORS
------

Sometimes you may do something which doesn't make sense. In most cases
e will display a message at the bottom of the screen explaining the
problem. Sometimes it just beeps and flashes.


INSERTING AND DELETING
----------------------

If you want to insert text, just type the text. Characters which you
can see, such as A, 7, *, etc. are taken by e as text and inserted
immediately. Type <Return> (the carriage-return key) to insert a
Newline character.

You can delete the last character you typed by typing <Delback>.
<Delback> is a key on the keyboard - the same one you normally use,
outside e, for deleting the last character you typed. It is
normally a large key a couple of lines up from the <Return> key, and
it is usually labeled "Delete", "Del" or "Backspace".

If the large key there is labeled "Backspace", then that's the one you
use for <Delback>. There may also be another key labeled "Delete"
somewhere else, but that's not <Delback>.

More generally, <Delback> deletes the character immediately before the
current cursor position.

>> Do this now - type a few characters, then delete them
   by typing <Delback> a few times. Don't worry about this file
   being changed; you will not alter the master tutorial. This is
   your personal copy of it.

You can delete a Newline character just like any other character.
Deleting the Newline character between two lines merges them into
one line.

>> Move the cursor to the beginning of a line and type <Delback>. This
   merges that line with the previous line.

>> Type <Return> to reinsert the Newline you deleted.

Remember that most e commands can be given a repeat count;
this includes text characters. Repeating a text character inserts
it several times.

>>  Try that now -- type C-u 8 * to insert ********.

You've now learned the most basic way of typing something in
e and correcting errors. You can delete by words or lines
as well. Here is a summary of the delete operations:

	<Delback>    Delete the character just before the cursor
	C-d   	     Delete the next character after the cursor

	M-<Delback>  Kill the word immediately before the cursor
	M-d	     Kill the next word after the cursor

	C-k	     Kill from the cursor position to end of line
	M-k	     Kill to the end of the current sentence

Notice that <Delback> and C-d vs M-<Delback> and M-d extend the parallel
started by C-f and M-f (well, <Delback> is not really a control
character, but let's not worry about that). C-k and M-k are like C-e
and M-e, sort of, in that lines are paired with sentences.

You can also kill any part of the text with one uniform method. Move
to one end of that part, and type C-@ or C-<SP> (either one). (<SP>
is the Space bar.)  Move to the other end of that part, and type C-w.
That kills all the text between the two positions.

>> Move the cursor to the Y at the start of the previous paragraph.
>> Type C-<SP>. e should display a message "Mark set"
   at the bottom of the screen.
>> Move the cursor to the n in "end", on the second line of the
   paragraph.
>> Type C-w. This will kill the text starting from the Y,
   and ending just before the n.

The difference between "killing" and "deleting" is that "killed" text
can be reinserted (at any position), whereas "deleted" things cannot
be reinserted in this way (you can, however, undo a deletion - see below).
Reinsertion of killed text is called "yanking". Generally, the
commands that can remove a lot of text kill the text (they are set up so
that you can yank the text), while the commands that remove just one
character, or only remove blank lines and spaces, do deletion (so you
cannot yank that text). <Delback> and C-d  do deletion in the simplest
case, with no argument. When given an argument, they kill instead.

>> Move the cursor to the  beginning of a line which is not empty.
   Then type C-k to kill the text on that line.
>> Type C-k a second time. You'll see that it kills the Newline
   which follows that line.

Note that a single C-k kills the contents of the line, and a second
C-k kills the line itself, and makes all the other lines move up. C-k
treats a numeric argument specially: it kills that many lines AND
their contents. This is not mere repetition. C-u 2 C-k kills two
lines and their newlines; typing C-k twice would not do that.

Bringing back killed text is called "yanking". (Think of it as
yanking back, or pulling back, some text that was taken away.)  You
can yank the killed text either at the same place where it was killed,
or at some other place in the text you are editing, or even in a
different file. You can yank the same text several times; that makes
multiple copies of it. Some other editors call killing and yanking
"cutting" and "pasting" (see the Glossary in the e manual).

The command for yanking is C-y. It reinserts the last killed text,
at the current cursor position.

>> Try it; type C-y to yank the text back.

If you do several C-k's in a row, all of the killed text is saved
together, so that one C-y will yank all of the lines at once.

>> Do this now, type C-k several times.

Now to retrieve that killed text:

>> Type C-y. Then move the cursor down a few lines and type C-y
   again. You now see how to copy some text.

What do you do if you have some text you want to yank back, and then
you kill something else? C-y would yank the more recent kill. But
the previous text is not lost. You can get back to it using the M-y
command. After you have done C-y to get the most recent kill, typing
M-y replaces that yanked text with the previous kill. Typing M-y
again and again brings in earlier and earlier kills. When you have
reached the text you are looking for, you do not have to do anything to
keep it. Just go on with your editing, leaving the yanked text where
it is.

If you M-y enough times, you come back to the starting point (the most
recent kill).

>> Kill a line, move around, kill another line.
   Then do C-y to get back the second killed line.
   Then do M-y and it will be replaced by the first killed line.
   Do more M-y's and see what you get. Keep doing them until
   the second kill line comes back, and then a few more.
   If you like, you can try giving M-y positive and negative
   arguments.


UNDO
----

If you make a change to the text, and then decide that it was a
mistake, you can undo the change with the undo command, C-x u.

Normally, C-x u undoes the changes made by one command; if you repeat
the C-x u several times in a row, each repetition undoes one
additional command.

But there are two exceptions: commands that do not change the text do
not count (this includes cursor motion commands and scrolling
commands), and consecutive single-character changes are grouped together.

>> Kill this line with C-k, then type C-x u and it should reappear.

C-_ is an alternative undo command; it works just the same as C-x u,
but it is easier to type several times in a row. The disadvantage of
C-_ is that on some keyboards it is not obvious how to type it. That
is why we provide C-x u as well. On some terminals, you can type C-_
by typing / while holding down CONTROL.

A numeric argument to C-_ or C-x u acts as a repeat count.

You can undo deletion of text just as you can undo killing of text.
The distinction between killing something and deleting it affects
whether you can yank it with C-y; it makes no difference for undo.


FILES
-----

In order to make the text you edit permanent, you must put it in a
file. Otherwise, it will go away when your invocation of e goes
away. In order to put your text in a file, you must "find" the file
before you enter the text. (This is also called "visiting" the file.)

Finding a file means that you see the contents of the file within
e. In many ways, it is as if you were editing the file itself.
However, the changes you make using e do not become permanent
until you "save" the file. This is so you can avoid leaving a
half-changed file on the system when you do not want to. Even when
you save, e leaves the original file under a changed name in case
you later decide that your changes were a mistake.

If you look near the bottom of the screen you will see a line that
begins and ends with dashes. This part of the screen normally shows
the name of the file that you are visiting. When you find a file with
e, that file's name will appear in that precise spot.

One special thing about the command for finding a file is that you
have to say what file name you want. We say the command "reads an
argument from the terminal" (in this case, the argument is the name of
the file). After you type the command

	C-x C-f   Find a file

e asks you to type the file name. The file name you type appears
on the bottom line of the screen.

While you are entering the file name, you can cancel the command with C-g.

>> Type C-x C-f, then type C-g. This cancels the C-x C-f command so
   you do not find any file.

When you have finished entering the file name, type <Return> to
terminate it. The C-x C-f command goes to work, and finds the file
you chose.

In a little while the file contents appear on the screen, and you can
edit the contents. When you wish to make your changes permanent,
type the command

	C-x C-s   Save the file

This copies the text within e into the file. 

When saving is finished, e displays the name of the file written.
You should save fairly often, so that you will not lose very much
work if the system should crash (see the section "Auto Save" below).

You can find an existing file, to view it or edit it. You can also
find a file which does not already exist. This is the way to create a
file with e: find the file, which will start out empty, and then
begin inserting the text for the file. When you ask to "save" the
file, e will really create the file with the text that you have
inserted. From then on, you can consider yourself to be editing an
already existing file.


EXTENDING THE COMMAND SET
-------------------------

There are many more e commands than could possibly be put
on all the control and meta characters. e gets around this with
the X (eXtend) command. This comes in two flavors:

	C-x	Character eXtend. Followed by one character.
	M-x	Named command eXtend. Followed by a long name.

These are commands that are generally useful but are used less than the
commands you have already learned about. You have already seen a few
of them: the file commands C-x C-f to Find and C-x C-s to Save, for
example. Another example is the command to end the e session - this
is the command C-x C-c. (Do not worry about losing changes you have
made; C-x C-c offers to save a changed file before it kills e.)

If you are using a graphical display that supports multiple
applications in parallel, you don't need any special command to move
from e to another application. You can do this with the mouse or
with window manager commands. However, if you're using a text
terminal which can only show one application at a time, you need to
"suspend" e to move to any other program.

C-z is the command to exit e *temporarily* - so that you can go
back to the same e session afterward. When e is running on a
text terminal, C-z "suspends" e; that is, it returns to the shell
but does not destroy the e. In the most common shells, you can
resume e with the 'fg' command.

The time to use C-x C-c is when you are about to log out. It's also
the right thing to use to exit an e invoked under mail handling
programs and other miscellaneous utilities, since they may not know
how to cope with suspension of e.

There are many C-x commands. Here is a list of the ones you have learned:

	C-x C-f		Find file
	C-x C-s		Save file
	C-x C-c		Quit e
	C-x u		Undo

Named eXtended commands are commands which are used even less
frequently, or commands which are used only in certain modes. An
example is the command replace-string, which globally replaces one
string with another. When you type M-x, e prompts you at the
bottom of the screen with M-x and you should type the name of the
command; in this case, "replace-string". Just type "repl s<TAB>" and
e will complete the name. (<TAB> is the Tab key, usually found
above the CapsLock or Shift key near the left edge of the keyboard.)
End the command name with <Return>.

The replace-string command requires two arguments - the string to be
replaced, and the string to replace it with. You must end each
argument with <Return>.

>> Move the cursor to the blank line two lines below this one.
   Then type M-x repl s<Return>changed<Return>altered<Return>.

   Notice how this line has changed: you've replaced
   the word c-h-a-n-g-e-d with "altered" wherever it occurred,
   after the initial position of the cursor.


MODE LINE
---------

The line second from the bottom is called the "mode line". The mode
line says something like this:

--- e --------------------------- filename * ------------------------- 59% ---

This line gives some information about the status of e and the text you
are editing.

You already know what the filename means - it is the file you have
found. NN% indicates your current position in the text; it means that
NN percent of the text is above the top of the screen. If the top of
the file is on the screen, it will say "Top" instead of " 0%". If the
bottom of the text is on the screen, it will say "Bot". If you are
looking at text so small that all of it fits on the screen, the mode
line says "All".

The star after the filename means that you have made changes to the text.
Right after you visit or save a file, there will be no star.


SEARCHING
---------

e can do searches for strings (these are groups of contiguous
characters or words) either forward through the text or backward
through it. Searching for a string is a cursor motion command;
it moves the cursor to the next place where that string appears.

The e search command is "incremental". This means that the
search happens while you type in the string 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 try them now.

When you type C-s you'll notice that the string "I-search" appears as
a prompt at the bottom of the screen. This tells you that e is in what
is called an incremental search waiting for you to type the thing that
you want to search for. <Return> 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.
   Now you have searched for "cursor", once.
>> Type C-s again, to search for the next occurrence of "cursor".
>> Now type <Delback> four times and see how the cursor moves.
>> Type <Return> to terminate the search.

Did you see what happened? e, 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, e beeps and tells you the search is currently
"failing". C-g would also terminate the search.

If you are in the middle of an incremental search and type <Delback>,
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 have typed "c", to search for the first
occurrence of "c". Now if you type "u", the cursor will move
to the first occurrence of "cu". Now type <Delback>. This erases
the "u" from the search string, and the cursor moves back to
the first occurrence of "c".

If you are in the middle of a search and type a control or meta
character (with a few exceptions - characters that are special in
a search, such as C-s and C-r), the search is terminated.

The C-s starts a search that looks for any occurrence of the search
string AFTER the current cursor position. If you want to search for
something earlier in the text, type C-r instead. Everything that we
have said about C-s also applies to C-r, except that the direction of
the search is reversed.


REPLACING TEXT
--------------

In addition to plain searching you can also do a search and replace.
This is invoked via M-%. It will prompt you for the string to
search for and the string to replace it with. Then you will be
in an interactive query-replace mode. The available options:

    SPACE or y      Do the replacement and move to the next instance
		    of the search string.
    <Delback> or n  Skip replacing this instance and move to the next one.
    !               Replace all remaining instances.
    ^               Switch to reverse search.
    CR / q / C-g    Exit query-replace mode.


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

In this tutorial we have tried to supply just enough information to
get you started using e. There is so much available in e that
it would be impossible to explain it all here. However, you may want
to learn more about e since it has many other useful features.
e provides commands for reading documentation about e
commands. These "help" commands all start with the character
CONTROL-h, which is called "the Help character".

To use the Help features, type the C-h character, and then a
character saying what kind of help you want. If you have typed C-h
and decide you do not want any help, just type C-g to cancel it.

(If C-h does not display a message about help at the bottom of the
screen, try typing the F1 key or M-x help <Return> instead.)

The most basic Help feature is C-h k. Type C-h, the character k, and
a command key or sequence; then e displays a very brief description of
the command.

>> Type C-h k C-p.

The message should be something like this:

	C-p - previous-line: Move to the previous line.

This tells you the "name of the function". Since function names
are chosen to indicate what the command does, they can serve as
very brief documentation - sufficient to remind you of commands you
have already learned.

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

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 displays all the information e has about the
   function which implements the C-p command.

   C-h a	Command Apropos. Type in a keyword and e 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 runs the same command.

>> Type C-h a file <Return>.

This displays a list of all M-x commands with "file" in their names.
You will see character-commands like C-x C-f listed beside the
corresponding command names such as find-file.

There's also a command-line flag to generate a list of all e commands
and what keys they are bound to:

   % e -commands

You can use it as a cheat sheet, or write your own help scripts based
on it.


CONCLUSION
----------

Remember, to exit use C-x C-c.

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 "teachemacs" Emacs
tutorials starting with the one written by Stuart Cracraft for the
original Emacs. It's also influenced by the teach-jove file from
JOVE, which itself is descended from teachemacs via another lineage.
All the versions are under Copyleft, so this is too. Feel free to
copy and adapt it, just note that others are free to copy it as well.
