info.texi

gcc-2.95.3 Linux下最常用的C编译器

>> Try that now.  (We have put in enough verbiage to push this past
the first screenful, but screens are so big nowadays that perhaps it
isn't enough.  You may need to shrink your Emacs or Info window.)
Then come back, with Spaces.

  If your screen is very tall, all of this node might fit at once.
In that case, "b" won't do anything.  Sorry; what can we do?

  You have just learned a considerable number of commands.  If you
want to use one but have trouble remembering which, you should type
a @key{?} which prints out a brief list of commands.  When you are
finished looking at the list, make it go away by pressing @key{SPC}
repeatedly.

>> Type a @key{?} now.  Press @key{SPC} to see consecutive screenfuls of
>> the list until finished.

  From now on, you will encounter large nodes without warning, and
will be expected to know how to use Space and Delete to move
around in them without being told.  Since not all terminals have
the same size screen, it would be impossible to warn you anyway.

>> Now type @kbd{n} to see the description of the @kbd{m} command.

@node Help-M, Help-Adv, Help-^L, Getting Started
@comment  node-name,  next,  previous,  up
@section Menus

Menus and the @kbd{m} command

  With only the @kbd{n} and @kbd{p} commands for moving between nodes, nodes
are restricted to a linear sequence.  Menus allow a branching
structure.  A menu is a list of other nodes you can move to.  It is
actually just part of the text of the node formatted specially so that
Info can interpret it.  The beginning of a menu is always identified
by a line which starts with @samp{* Menu:}.  A node contains a menu if and
only if it has a line in it which starts that way.  The only menu you
can use at any moment is the one in the node you are in.  To use a
menu in any other node, you must move to that node first. 

  After the start of the menu, each line that starts with a @samp{*}
identifies one subtopic.  The line usually contains a brief name
for the subtopic (followed by a @samp{:}), the name of the node that talks
about that subtopic, and optionally some further description of the
subtopic.  Lines in the menu that do not start with a @samp{*} have no
special meaning---they are only for the human reader's benefit and do
not define additional subtopics.  Here is an example:

@example
* Foo:  FOO's Node      This tells about FOO
@end example

The subtopic name is Foo, and the node describing it is @samp{FOO's Node}.
The rest of the line is just for the reader's Information.
[[ But this line is not a real menu item, simply because there is
no line above it which starts with @samp{* Menu:}.]]

  When you use a menu to go to another node (in a way that will be
described soon), what you specify is the subtopic name, the first
thing in the menu line.  Info uses it to find the menu line, extracts
the node name from it, and goes to that node.  The reason that there
is both a subtopic name and a node name is that the node name must be
meaningful to the computer and may therefore have to be ugly looking.
The subtopic name can be chosen just to be convenient for the user to
specify.  Often the node name is convenient for the user to specify
and so both it and the subtopic name are the same.  There is an
abbreviation for this:

@example
* Foo::   This tells about FOO
@end example

@noindent
This means that the subtopic name and node name are the same; they are
both @samp{Foo}.

>> Now use Spaces to find the menu in this node, then come back to
   the front with a @kbd{b} and some Spaces.  As you see, a menu is
   actually visible in its node.  If you cannot find a menu in a node
   by looking at it, then the node does not have a menu and the
   @kbd{m} command is not available.

  The command to go to one of the subnodes is @kbd{m}---but @emph{do
not do it yet!}  Before you use @kbd{m}, you must understand the
difference between commands and arguments.  So far, you have learned
several commands that do not need arguments.  When you type one, Info
processes it and is instantly ready for another command.  The @kbd{m}
command is different: it is incomplete without the @dfn{name of the
subtopic}.  Once you have typed @kbd{m}, Info tries to read the
subtopic name.

  Now look for the line containing many dashes near the bottom of the
screen.  There is one more line beneath that one, but usually it is
blank.  If it is empty, Info is ready for a command, such as @kbd{n}
or @kbd{b} or Space or @kbd{m}.  If that line contains text ending
in a colon, it mean Info is trying to read the @dfn{argument} to a
command.  At such times, commands do not work, because Info tries to
use them as the argument.  You must either type the argument and
finish the command you started, or type @kbd{Control-g} to cancel the
command.  When you have done one of those things, the line becomes
blank again.

  The command to go to a subnode via a menu is @kbd{m}.  After you type
the @kbd{m}, the line at the bottom of the screen says @samp{Menu item: }.
You must then type the name of the subtopic you want, and end it with
a @key{RET}.

  You can abbreviate the subtopic name.  If the abbreviation is not
unique, the first matching subtopic is chosen.  Some menus put
the shortest possible abbreviation for each subtopic name in capital
letters, so you can see how much you need to type.  It does not
matter whether you use upper case or lower case when you type the
subtopic.  You should not put any spaces at the end, or inside of the
item name, except for one space where a space appears in the item in
the menu.

  You can also use the @dfn{completion} feature to help enter the subtopic
name.  If you type the Tab key after entering part of a name, it will
magically fill in more of the name---as much as follows uniquely from
what you have entered.

  If you move the cursor to one of the menu subtopic lines, then you do
not need to type the argument: you just type a Return, and it stands for
the subtopic of the line you are on.

Here is a menu to give you a chance to practice.

* Menu:    The menu starts here.

This menu gives you three ways of going to one place, Help-FOO.

* Foo:  Help-FOO.       A node you can visit for fun.@*
* Bar:  Help-FOO.       Strange!  two ways to get to the same place.@*
* Help-FOO::            And yet another!@*


>>  Now type just an @kbd{m} and see what happens:

  Now you are ``inside'' an @kbd{m} command.  Commands cannot be used
now; the next thing you will type must be the name of a subtopic.

  You can change your mind about doing the @kbd{m} by typing Control-g.

>> Try that now;  notice the bottom line clear.

>> Then type another @kbd{m}.

>> Now type @samp{BAR} item name.  Do not type Return yet.

  While you are typing the item name, you can use the Delete key to
cancel one character at a time if you make a mistake.

>> Type one to cancel the @samp{R}.  You could type another @samp{R} to
   replace it.  You do not have to, since @samp{BA} is a valid abbreviation.

>> Now you are ready to go.  Type a @key{RET}.

  After visiting Help-FOO, you should return here.

>> Type @kbd{n} to see more commands.

@c If a menu appears at the end of this node, remove it.
@c It is an accident of the menu updating command.

Here is another way to get to  Help-FOO, a menu.  You can ignore this
if you want, or else try it (but then please come back to here).

@menu
* Help-FOO::
@end menu

@node Help-FOO,  ,  , Help-M
@comment  node-name,  next,  previous,  up
@subsection The @kbd{u} command

  Congratulations!  This is the node @samp{Help-FOO}.  Unlike the other
nodes you have seen, this one has an @samp{Up}: @samp{Help-M}, the node you
just came from via the @kbd{m} command.  This is the usual
convention---the nodes you reach from a menu have @samp{Up} nodes that lead
back to the menu.  Menus move Down in the tree, and @samp{Up} moves Up.
@samp{Previous}, on the other hand, is usually used to ``stay on the same
level but go backwards''

  You can go back to the node @samp{Help-M} by typing the command
@kbd{u} for ``Up''.  That puts you at the @emph{front} of the
node---to get back to where you were reading you have to type
some @key{SPC}s.

>> Now type @kbd{u} to move back up to @samp{Help-M}.

@node Help-Adv, Help-Q, Help-M, Getting Started
@comment  node-name,  next,  previous,  up
@section Some advanced Info commands

  The course is almost over, so please stick with it to the end.

  If you have been moving around to different nodes and wish to
retrace your steps, the @kbd{l} command (@kbd{l} for @dfn{last}) will
do that, one node-step at a time.  As you move from node to node, Info
records the nodes where you have been in a special history list.  The
@kbd{l} command revisits nodes in the history list; each successive
@kbd{l} command moves one step back through the history.

  If you have been following directions, ad @kbd{l} command now will get
you back to @samp{Help-M}.  Another @kbd{l} command would undo the
@kbd{u} and get you back to @samp{Help-FOO}.  Another @kbd{l} would undo
the @kbd{m} and get you back to @samp{Help-M}.

>> Try typing three @kbd{l}'s, pausing in between to see what each
    @kbd{l} does.

Then follow directions again and you will end up back here.

  Note the difference between @kbd{l} and @kbd{p}: @kbd{l} moves to
where @emph{you} last were, whereas @kbd{p} always moves to the node
which the header says is the @samp{Previous} node (from this node, to
@samp{Help-M}).

  The @samp{d} command gets you instantly to the Directory node.
This node, which is the first one you saw when you entered Info,
has a menu which leads (directly, or indirectly through other menus),
to all the nodes that exist.

>> Try doing a @samp{d}, then do an @kbd{l} to return here (yes,
   @emph{do} return).

  Sometimes, in Info documentation, you will see a cross reference.
Cross references look like this: @xref{Help-Cross, Cross}.  That is a
real, live cross reference which is named @samp{Cross} and points at
the node named @samp{Help-Cross}.

  If you wish to follow a cross reference, you must use the @samp{f}
command.  The @samp{f} must be followed by the cross reference name
(in this case, @samp{Cross}).  While you enter the name, you can use the
Delete key to edit your input.  If you change your mind about following
any reference, you can use @kbd{Control-g} to cancel the command.

  Completion is available in the @samp{f} command; you can complete among
all the cross reference names in the current node by typing a Tab.

>> Type @samp{f}, followed by @samp{Cross}, and a @key{RET}.

  To get a list of all the cross references in the current node, you can
type @kbd{?} after an @samp{f}.  The @samp{f} continues to await a
cross reference name even after printing the list, so if you don't
actually want to follow a reference, you should type a @kbd{Control-g}
to cancel the @samp{f}.

>> Type "f?" to get a list of the cross references in this node.  Then
   type a @kbd{Control-g} and see how the @samp{f} gives up.

>> Now type @kbd{n} to see the last node of the course.

@c If a menu appears at the end of this node, remove it.
@c It is an accident of the menu updating command.

@node Help-Cross,  ,  , Help-Adv
@comment  node-name,  next,  previous,  up
@unnumberedsubsec The node reached by the cross reference in Info

  This is the node reached by the cross reference named @samp{Cross}.

  While this node is specifically intended to be reached by a cross
reference, most cross references lead to nodes that ``belong''
someplace else far away in the structure of Info.  So you cannot expect
the footnote to have a @samp{Next}, @samp{Previous} or @samp{Up} pointing back to
where you came from.  In general, the @kbd{l} (el) command is the only
way to get back there.

>> Type @kbd{l} to return to the node where the cross reference was.

@node Help-Q,  , Help-Adv, Getting Started
@comment  node-name,  next,  previous,  up
@section Quitting Info

  To get out of Info, back to what you were doing before, type @kbd{q}
for @dfn{Quit}.

  This is the end of the course on using Info.  There are some other
commands that are meant for experienced users; they are useful, and you
can find them by looking in the directory node for documentation on
Info.  Finding them will be a good exercise in using Info in the usual
manner.

>> Type @samp{d} to go to the Info directory node; then type
   @samp{mInfo} and Return, to get to the node about Info and
   see what other help is available.

@node Advanced Info, Create an Info File, Getting Started, Top
@comment  node-name,  next,  previous,  up
@chapter Info for Experts

This chapter describes various advanced Info commands, and how to write
an Info as distinct from a Texinfo file.  (However, in most cases, writing a
Texinfo file is better, since you can use it @emph{both} to generate an
Info file and to make a printed manual.  @xref{Top,, Overview of
Texinfo, texinfo, Texinfo: The GNU Documentation Format}.)

@menu
* Expert::               Advanced Info commands: g, s, e, and 1 - 5.
* Add::                  Describes how to add new nodes to the hierarchy.
                           Also tells what nodes look like.
* Menus::                How to add to or create menus in Info nodes.
* Cross-refs::           How to add cross-references to Info nodes.