Info is a program, which you are using now, for reading documentation of computer programs. The GNU Project distributes most of its on-line manuals in the Info format, so you need a program called Info reader to read the manuals. One of such programs you are using now.
This first part of the Info manual describes how to get around inside of Info. The second part of the manual describes various advanced Info commands, and how to write an Info as distinct from a Texinfo file. The third part briefly explains how to generate Info files from Texinfo files.
This manual is primarily designed for browsing with an Info reader program on a computer, so that you can try Info commands while reading about them. Reading it on paper or with an HTML browser is less effective, since you must take it on faith that the commands described really do what the manual says. By all means go through this manual now that you have it; but please try going through the on-line version as well.
There are two ways of looking at the online version of this manual:
info at your shell's command line. This approach uses a
stand-alone program designed just to read Info files.
emacs at the command line; then type C-h i
(Control-h, followed by i). This approach uses the Info
mode of the Emacs program, an editor with many other capabilities.
In either case, then type mInfo (just the letters), followed by <RET>--the "Return" or "Enter" key. At this point, you should be ready to follow the instructions in this manual as you read them on the screen.
(In Info, you only see this section if your terminal has a small number of lines; most readers pass by it without seeing it.)
Since your terminal has a relatively small number of lines on its screen, it is necessary to give you special advice at the beginning.
If you see the text --All---- near the bottom right corner
of the screen, it means the entire text you are looking at fits on the
screen. If you see --Top---- instead, it means that there is
more text below that does not fit. To move forward through the text
and see another screen full, press <SPC>, the Space bar. To move
back up, press the key labeled Backspace or DEL (on some
keyboards, this key might be labeled Delete).
You are talking to the program Info, for reading documentation.
Right now you are looking at one Node of Information.
A node contains text describing a specific topic at a specific
level of detail. This node's topic is "how to use Info". The mode
line says that this is node Help in the file info.
The top line of a node is its header. This node's header (look at
it now) says that the Next node after this one is the node
called Help-P. An advanced Info command lets you go to any node
whose name you know. In the stand-alone Info reader program, the
header line shows the names of this node and the info file as well.
In Emacs, the header line is displayed in a special typeface, and it
doesn't scroll off the screen when you scroll the display. The names
of this node and of its Info file are omitted by Emacs from the header
line.
Besides a Next, a node can have a Previous or an
Up links, or both. As you can see, this node has all of these
links.
Now it is time to move on to the Next node, named Help-P.
>> Type n to move there. Type just one character; do not type the quotes and do not type a <RET> afterward.
>> in the margin means it is really time to try a command.
>> If you have a mouse, and if you already practiced typing n
to get to the next node, click now with the right mouse button on
the Next link to do the same ``the mouse way''.
This node is called Help-P. The Previous node, as you see,
is Help, which is the one you just came from using the n
command. Another n command now would take you to the next
node, Help-^L. In Emacs, n runs the Emacs command
Info-next, and p runs Info-prev.
>> But do not type n yet. First, try the p command, or click the mouse on thePrevlink, which takes you to thePreviousnode. When you get there, you can do an n again to return here.
If you read this in Emacs, you will see an Info item in the
menu bar, close to its right edge. Clicking your mouse on the
Info menu-bar item opens a menu of commands which include
Next and Prev (and also some others which you didn't yet
learn about).
This all probably seems insultingly simple so far, but do not be
led into skimming. Things will get more complicated soon. Also,
do not try a new command until you are told it is time to. Otherwise,
you may make Info skip past an important warning that was coming up.
>> Now do an n, or click the mouse on theNextlink, to get to the nodeHelp-^Land learn more.
This node's mode line tells you that you are now at node Help-^L,
and the header line tells you that p would get you back to
Help-P. The node's title is underlined; it says what the node
is about (most nodes have titles).
This is a big node and it does not all fit on your display screen.
You can tell that there is more that is not visible because you
can see the string --Top----- rather than --All---- near
the bottom right corner of the screen.
The <SPC>, <BACKSPACE> (or <DEL>)1 and b commands exist to
allow you to "move around" in a node that does not all fit on the
screen at once. <SPC> moves forward, to show what was below the
bottom of the screen. <DEL> or <BACKSPACE> moves backward, to
show what was above the top of the screen (there is not anything above
the top until you have typed some spaces). In Emacs, <SPC> runs
the command Info-scroll-up, while <BACKSPACE> runs
Info-scroll-down.
>> Now try typing a <SPC> (afterward, type a <BACKSPACE> to return here).
When you type the <SPC>, the two lines that were at the bottom of the screen appear at the top, followed by more lines. <DEL> or <BACKSPACE> takes the two lines from the top and moves them to the bottom, usually, but if there are not a full screen's worth of lines above them they may not make it all the way to the bottom.
If you are reading this in Emacs, note that the header line is
always visible, never scrolling off the display. That way, you can
always see the Next, Prev, and Up links, and you
can conveniently go to one of these links from anywhere in the node by
clicking the mouse on one of these links.
<SPC> and <DEL> not only move forward and backward through the current node. When these keys hit the beginning or the end of the current node, they move to preceding or subsequent nodes. Specifically, they scroll through all the nodes in an Info file as a single logical sequence. In this sequence, a node's subnodes appear following their parent. If a node has a menu, <SPC> takes you into the subnodes listed in the menu, one by one. Once you reach the end of a node, and have seen all of its subnodes, <SPC> takes you to the next node or to the parent's next node. This is so you could read the entire manual top to bottom by just typing <SPC>.
Many keyboards nowadays have two scroll keys labeled PageUp
and PageDown (or maybe Prior and Next). If your
keyboard has these keys, you can use them to move forward and backward
through the text, like with <SPC> and <BACKSPACE>. However,
unlike <SPC> and <BACKSPACE>, <PAGEUP> and <PAGEDOWN>
keys will never scroll beyond the beginning or the end of the current
node.
If your screen is ever garbaged, you can tell Info to display it
again by typing C-l (Control-L, that is--hold down
<CTRL> and type L or l).
>> Type C-l now.
To move back to the beginning of the node you are on, you can type
a lot of <BACKSPACE> keys. You can also type simply b for
beginning.
>> 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 <SPS>s.
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 ? (in Emacs it runs the Info-summary command) which
displays a brief list of commands. When you are finished looking at
the list, make it go away by typing a <SPC> repeatedly.
>> Type a <?> now. Press <SPC> to see consecutive screenfuls of the list until finished. Then type <SPC> several times, until it goes away.
(If you are using the stand-alone Info reader, type C-x 0 to return here, that is--press and hold <CTRL>, type an x, then release <CTRL> and x, and press 0--a zero, not the letter "o".)
From now on, you will encounter large nodes without warning, and
will be expected to know how to use <SPC> and <BACKSPACE> 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 n, or click the mouse on the Next link, to
see the description of the m command.
With only the n (next) and p (previous) 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 * 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 *
identifies one subtopic. The line usually contains a brief name
for the subtopic (followed by a :), 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 * have no
special meaning--they are only for the human reader's benefit and do
not define additional subtopics. Here is an example:
* Foo: Node about FOO This tells about FOO
The subtopic name is Foo, and the node describing it is Node
about FOO. 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 * 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:
* Foo:: This tells about FOO
This means that the subtopic name and node name are the same; they are
both Foo.
>> Now use <SPC> to find the menu in this node, then come back to the front with a b and some <SPC>s. 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 m command is not available.
The command to go to one of the subnodes is m--but do not do it yet! Before you use m, you need to learn about commands which prompt you for more input. So far, you have learned several commands that do not need additional input; when you typed one, Info processed it and was instantly ready for another command. The m command is different: it is incomplete without the name of the subtopic. Once you have typed 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 n or b or <SPC> or m. If that line contains text ending in a colon, it means Info is trying to read more input for the last command. At such times, commands do not work, because Info tries to use them as the input it needs. You must either type your response and finish the command you started, or type 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 m. After you type
the m, the line at the bottom of the screen says Menu item: .
You must then type the name of the subtopic you want, and end it with
a <RET>. In Emacs, m runs the command Info-menu.
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 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 <RET>, and it stands for the subtopic of the line you are on.
Here is a menu to give you a chance to practice. This menu gives you three ways of going to one place, Help-FOO:
>> Now type just an m and see what happens:
Now you are "inside" an 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 m by typing
Control-g.
>> Try that now; notice the bottom line clear.
>> Then type another m.
>> Now type BAR, the item name. Do not type <RET> yet.
While you are typing the item name, you can use the <DEL> (or
<BACKSPACE>) key to cancel one character at a time if you make a
mistake.
>> Press <DEL> to cancel theR. You could type another R to replace it. But you do not have to, sinceBAis a valid abbreviation.
>> Now you are ready to go. Type a <RET>.
After visiting Help-FOO, you should return here.
Another way to move to the menu subtopic lines and between them is
to type <TAB>. Each time you type a <TAB>, you move to the
next subtopic line. To move to a previous subtopic line, type
M-<TAB>--that is, press and hold the <META> key and then
press <TAB>. (On some keyboards, the <META> key might be labeled
Alt.)
Once you move cursor to a subtopic line, press <RET> to go to that subtopic's node.
If your terminal supports a mouse, you have yet another way of going
to a subtopic. Move your mouse pointer to the subtopic line,
somewhere between the beginning * and the colon : which
ends the subtopic's brief name. You will see the subtopic's name
change its appearance (usually, its background color will change), and
the shape of the mouse pointer will change if your platform supports
that. After a while, if you leave the mouse on that spot, a tooltip
will pop up saying "Mouse-2: go to that node". (If the tooltips are
turned off or unavailable, this message is displayed in the echo
area, the bottom screen line where you typed the menu subtopics in
response to the prompt.) Mouse-2 is the second button of your
mouse counting from the left--the rightmost button for two-button
mice, the middle button for 3-button mice. So pressing Mouse-2
while the mouse pointer is on a menu subtopic goes to that subtopic.
More generally, Mouse-2 in an Info buffer runs the Emacs
command Info-mouse-follow-nearest-node, which finds the nearest
link to another node and goes there. For example, near a cross
reference it acts like f, in a menu it acts like m, on the
node's header line it acts like n, p, or u, etc. At
end of the node's text Mouse-2 moves to the next node, or up if
there's no next node.
Here is another way to get to Help-FOO, a menu. You can ignore this if you want, or else try it by typing <TAB> and then <RET>, or clicking Mouse-2 on it (but then please come back to here).
>> Type n to see more commands.
Congratulations! This is the node Help-FOO. It has an Up
pointer Help-M, the node you just came from via the m
command. This is the usual convention--the nodes you reach from a menu
have Up nodes that lead back to the menu. Menus move Down in the
tree, and Up moves Up. Previous, on the other hand, is
usually used to "stay on the same level but go backwards".
You can go back to the node Help-M by typing the command
u for "Up" (the Emacs command run by u is
Info-up). That puts you at the front of the node--to
get back to where you were reading you have to type some <SPC>s.
(Some Info readers, such as the one built into Emacs, put you at the
same place where you were reading in Help-M.)
Another way to go Up is to click on the Up pointer shown in
the header line (provided that you have a mouse).
>> Now type u to move back up to Help-M.
In Info documentation, you will see many cross references.
Cross references look like this: See Cross. That text
is a real, live cross reference, whose name is Cross and which
points to the node named Help-Cross.
There are two ways to follow a cross reference. You can move the
cursor to it and press <RET>, just as in a menu. <RET>
follows the cross reference that the cursor is on. Or you can type
f and then specify the name of the cross reference (in this
case, Cross) as an argument. In Emacs Info, f runs
Info-follow-reference,
In the f command, you select the cross reference with its
name, so it does not matter where the cursor was. If the cursor is on
or near a cross reference, f suggests that reference name in
parentheses as the default; typing <RET> will follow that
reference. However, if you type a different reference name, f
will follow the other reference which has that name.
>> Type f, followed by Cross, and then <RET>.
As you enter the reference name, you can use the <DEL> (or <BACKSPACE>) key to edit your input. If you change your mind about following any reference, you can use Control-g to cancel the command. Completion is available in the f command; you can complete among all the cross reference names in the current node by typing a <TAB>.
To get a list of all the cross references in the current node, you
can type ? after an f. The f continues to await a
cross reference name even after displaying the list, so if you don't
actually want to follow a reference, you should type a Control-g
to cancel the f.
>> Type f? to get a list of the cross references in this node. Then
type a Control-g and see how the f gives up.
The <TAB> and M-<TAB> key, which move between menu items in a menu, also move between cross references outside of menus.
The introductory course is almost over; please continue a little longer to learn some intermediate-level commands.
Most Info files have an index, which is actually a large node that contains nothing but a menu. The menu has one menu item for each topic listed in the index. You can find the index node from the main menu of the file, with the m command; then you can use the m command again in the index node to go to the node that describes the topic.
There is also a short-cut Info command, i, which does all of that for you. It searches the index for a given topic (a string) and goes to the node which is listed in the index for that topic. See Info Search, for a full explanation.
If you have been moving around to different nodes and wish to retrace your steps, the l command (l for 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 l command revisits nodes in the history list; each successive l command moves one step back through the history.
If you have been following directions, ad l command now will get
you back to Help-M. Another l command would undo the
u and get you back to Help-FOO. Another l would undo
the m and get you back to Help-M.
In Emacs, l runs the command Info-last.
>> Try typing three l's, pausing in between to see what each l does. Then follow directions again and you will end up back here.
Note the difference between l and p: l moves to
where you last were, whereas p always moves to the node
which the header says is the Previous node (from this node, the
Prev link leads to Help-M).
The d command (Info-directory in Emacs) 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. The
Directory node lists all the manuals and other Info documents that
are, or could be, installed on your system.
>> Try doing a d, then do an l to return here (yes, do return).
The t command moves to the Top node of the manual.
This is useful if you want to browse the manual's main menu, or select
some specific top-level menu item. The Emacs command run by t
is Info-top-node.
Clicking Mouse-2 on or near a cross reference also follows the
reference. You can see that the cross reference is mouse-sensitive by
moving the mouse pointer to the reference and watching how the
underlying text and the mouse pointer change in response.
>> Now type n to see the last node of the course.
See Advanced Info, for more advanced Info features.
This chapter describes various advanced Info commands. (If you are using a stand-alone Info reader, there are additional commands specific to it, which are documented in several chapters of GNU Info.)
This chapter also explains 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 both to generate an Info file and to make a printed manual. See Overview of Texinfo.)
Here are some more Info commands that make it easier to move around.
If you know a node's name, you can go there by typing g, the
name, and <RET>. Thus, gTop<RET> would go to the node
called Top in this file. (This is equivalent to t, see
Help-Int.) gExpert<RET> would come back here.
g in Emacs runs the command Info-goto-node.
Unlike m, g does not allow the use of abbreviations. But it does allow completion, so you can type <TAB> to complete a partial node name.
To go to a node in another file, you can include the file name in the
node name by putting it at the front, in parentheses. Thus,
g(dir)Top<RET> would go to the Info Directory node, which is
the node Top in the Info file dir. Likewise,
g(emacs)Top<RET> goes to the top node of the Emacs manual.
The node name * specifies the whole file. So you can look at
all of the current file by typing g*<RET> or all of any
other file with g(filename)<RET>.
If you begrudge each character of type-in which your system requires,
you might like to use the commands 1, 2, 3, 4,
..., 9. They are short for the m command together
with a name of a menu subtopic. 1 goes through the first item
in the current node's menu; 2 goes through the second item, etc.
In the stand-alone reader, 0 goes through the last menu item;
this is so you need not count how many entries are there. In Emacs,
the digit keys run the command Info-nth-menu-item.
If your display supports multiple fonts, and you are using Emacs'
Info mode to read Info files, the * for the fifth menu item
stands out, either in color or in some other attribute, such as
underline, and so is the * for the ninth item; this makes it
easy to see at a glance which number to use for an item.
Some terminals don't support colors or underlining. If you need to actually count items, it is better to use m instead, and specify the name, or use <TAB> to quickly move between menu items.
The Info command e changes from Info mode to an ordinary
Emacs editing mode, so that you can edit the text of the current node.
Type C-c C-c to switch back to Info. The e command is allowed
only if the variable Info-enable-edit is non-nil.
The e command only works in Emacs, where it runs the command
Info-edit. The stand-alone Info reader doesn't allow you to
edit the Info file, so typing e there goes to the end of the
current node.
The commands which move between and inside nodes allow you to read the entire manual or its large portions. But what if you need to find some information in the manual as fast as you can, and you don't know or don't remember in what node to look for it? This need arises when you use a manual as a reference, or when it is impractical to read the entire manual before you start using the programs it describes.
Info has powerful searching facilities that let you find things quickly. You can search either the manual indices or its text.
Since most subjects related to what the manual describes should be indexed, you should try the index search first. The i command prompts you for a subject and then looks up that subject in the indices. If it finds an index entry with the subject you typed, it goes to the node to which that index entry points. You should browse through that node to see whether the issue you are looking for is described there. If it isn't, type , one or more times to go through additional index entries which match your subject.
The i command finds all index entries which include the string you typed as a substring. For each match, Info shows in the echo area the full index entry it found. Often, the text of the full index entry already gives you enough information to decide whether it is relevant to what you are looking for, so we recommend that you read what Emacs shows in the echo are before looking at the node it displays.
Since i looks for a substring, you can search for subjects even if you are not sure how they are spelled in the index. For example, suppose you want to find something that is pertinent to commands which complete partial input (e.g., when you type <TAB>). If you want to catch index entries that refer to "complete", "completion", and "completing", you could type icomplet<RET>.
Info documents which describe programs should index the commands,
options, and key sequences that the program provides. If you are
looking for a description of a command, an option, or a key, just type
their names when i prompts you for a topic. For example, if you
want to read the description of what the C-f key does, type
iC-f<RET>. Here C-f are 3 literal characters
C, -, and f, not the "Control-f" command key
you type inside Emacs to run the command bound to C-f.
In Emacs, i runs the command Info-index.
The s command allows you to search a whole file for a string.
It switches to the next node if and when that is necessary. You
type s followed by the string to search for, terminated by
<RET>. To search for the same string again, just s followed
by <RET> will do. The file's nodes are scanned in the order
they are in in the file, which has no necessary relationship to the
order that they may be in the tree structure of menus and next
pointers. But normally the two orders are not very different. In any
case, you can always do a b to find out what node you have
reached, if the header is not visible (this can happen, because s
puts your cursor at the occurrence of the string, not at the beginning
of the node).
In Emacs, Meta-s is equivalent to s. That is for
compatibility with other GNU packages that use M-s for a similar
kind of search command. Both s and M-s run in Emacs the
command Info-search.
To add a new topic to the list in the Info directory, you must:
Usually, the way to create the nodes is with Texinfo (see Overview of Texinfo); this has the advantage that you can also make a printed manual from them. However, if you want to edit an Info file, here is how.
The new node can live in an existing documentation file, or in a new
one. It must have a ^_ character before it (invisible to the
user; this node has one but you cannot see it), and it ends with either
a ^_, a ^L ("formfeed"), or the end of file.2
The ^_ starting a node must be followed by a newline or a
^L newline, after which comes the node's header line. The header
line must give the node's name (by which Info finds it), and state the
names of the Next, Previous, and Up nodes (if there
are any). As you can see, this node's Up node is the node
Top, which points at all the documentation for Info. The
Next node is Menus.
The keywords Node, Next, Previous, and Up may appear in any order, anywhere in the header line, but the recommended order is the one in this sentence. Each keyword must be followed by a colon, spaces and tabs, and then the appropriate name. The name may be terminated with a tab, a comma, or a newline. A space does not end it; node names may contain spaces. The case of letters in the names is insignificant.
A node name has two forms. A node in the current file is named by
what appears after the Node: in that node's first line. For
example, this node's name is Add. A node in another file is
named by (filename)node-within-file, as in
(info)Add for this node. If the file name starts with "./",
then it is relative to the current directory; otherwise, it is
relative starting from the standard directory for Info files of your
site. The name (filename)Top can be abbreviated to just
(filename). By convention, the name Top is used
for the "highest" node in any single file--the node whose Up
points out of the file. The Directory node is (dir), it
points to a file dir which holds a large menu listing all the
Info documents installed on your site. The Top node of a
document file listed in the Directory should have an Up:
(dir) in it.
The node name * is special: it refers to the entire file. Thus, g* shows you the whole current file. The use of the node * is to make it possible to make old-fashioned, unstructured files into nodes of the tree.
The Node: name, in which a node states its own name, must not
contain a file name, since when Info searches for a node, it does not
expect a file name to be there. The Next, Previous and
Up names may contain them. In this node, since the Up
node is in the same file, it was not necessary to use one.
Note that the nodes in this file have a file name in the header line. The file names are ignored by Info, but they serve as comments to help identify the node for the user.
Any node in the Info hierarchy may have a menu--a list of subnodes. The m command searches the current node's menu for the topic which it reads from the terminal.
A menu begins with a line starting with * Menu:. The rest of the
line is a comment. After the starting line, every line that begins
with a * lists a single topic. The name of the topic-what
the user must type at the m's command prompt to select this
topic--comes right after the star and space, and is followed by a
colon, spaces and tabs, and the name of the node which discusses that
topic. The node name, like node names following Next, Previous
and Up, may be terminated with a tab, comma, or newline; it may also
be terminated with a period.
If the node name and topic name are the same, then rather than
giving the name twice, the abbreviation * name:: may be
used (and should be used, whenever possible, as it reduces the visual
clutter in the menu).
It is considerate to choose the topic names so that they differ from each other very near the beginning--this allows the user to type short abbreviations. In a long menu, it is a good idea to capitalize the beginning of each item name which is the minimum acceptable abbreviation for it (a long menu is more than 5 or so entries).
The nodes listed in a node's menu are called its "subnodes", and it
is their "superior". They should each have an Up: pointing at
the superior. It is often useful to arrange all or most of the subnodes
in a sequence of Next and Previous pointers so that
someone who wants to see them all need not keep revisiting the Menu.
The Info Directory is simply the menu of the node (dir)Top--that
is, node Top in file .../info/dir. You can put new entries
in that menu just like any other menu. The Info Directory is not the
same as the file directory called info. It happens that many of
Info's files live in that file directory, but they do not have to; and
files in that directory are not automatically listed in the Info
Directory node.
Also, although the Info node graph is claimed to be a "hierarchy",
in fact it can be any directed graph. Shared structures and
pointer cycles are perfectly possible, and can be used if they are
appropriate to the meaning to be expressed. There is no need for all
the nodes in a file to form a connected structure. In fact, this file
has two connected components. You are in one of them, which is under
the node Top; the other contains the node Help which the
h command goes to. In fact, since there is no garbage
collector, nothing terrible happens if a substructure is not pointed
to, but such a substructure is rather useless since nobody can
ever find out that it exists.
A cross reference can be placed anywhere in the text, unlike a menu
item which must go at the front of a line. A cross reference looks
like a menu item except that it has *note instead of *.
It cannot be terminated by a ), because )'s are
so often part of node names. If you wish to enclose a cross reference
in parentheses, terminate it with a period first. Here are two
examples of cross references pointers:
*Note details: commands. (See *note 3: Full Proof.)
These are just examples. The places they "lead to" do not really exist!
This is the node reached by the cross reference named 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 an Info document. So you
cannot expect this node to have a Next, Previous or
Up links pointing back to where you came from. In general, the
l (el) command is the only way to get back there.
>> Type l to return to the node where the cross reference was.
To get out of Info, back to what you were doing before, type q
for Quit. This runs Info-exit in Emacs.
This is the end of the basic course on using Info. You have learned how to move in an Info document, and how to follow menus and cross references. This makes you ready for reading manuals top to bottom, as new users should do when they learn a new package.
Another set of Info commands is useful when you need to find something quickly in a manual--that is, when you need to use a manual as a reference rather than as a tutorial. We urge you to make learn these search commands as well. If you want to do that now, follow this cross reference to Info Search.
Yet another set of commands are meant for experienced users; 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 d to go to the Info directory node; then type mInfo and Return, to get to the node about Info and see what other help is available.
You can speed up the access to nodes of a large Info file by giving it a tags table. Unlike the tags table for a program, the tags table for an Info file lives inside the file itself and is used automatically whenever Info reads in the file.
To make a tags table, go to a node in the file using Emacs Info mode and type
M-x Info-tagify. Then you must use C-x C-s to save the
file. Info files produced by the makeinfo command that is part
of the Texinfo package always have tags tables to begin with.
Once the Info file has a tags table, you must make certain it is up
to date. If you edit an Info file directly (as opposed to editing its
Texinfo source), and, as a result of deletion of text, any node moves back
more than a thousand characters in the file from the position
recorded in the tags table, Info will no longer be able to find that
node. To update the tags table, use the Info-tagify command
again.
An Info file tags table appears at the end of the file and looks like
this:
^_^L Tag Table: File: info, Node: Cross-refs^?21419 File: info, Node: Tags^?22145 ^_ End Tag Table
Note that it contains one line per node, and this line contains
the beginning of the node's header (ending just after the node name),
a DEL character, and the character position in the file of the
beginning of the node.
When creating an Info file, it is easy to forget the name of a node when
you are making a pointer to it from another node. If you put in the
wrong name for a node, this is not detected until someone tries to go
through the pointer using Info. Verification of the Info file is an
automatic process which checks all pointers to nodes and reports any
pointers which are invalid. Every Next, Previous, and
Up is checked, as is every menu item and every cross reference. In
addition, any Next which does not have a Previous pointing
back is reported. Only pointers within the file are checked, because
checking pointers to other files would be terribly slow. But those are
usually few.
To check an Info file, do M-x Info-validate while looking at any node of the file with Emacs Info mode.
The following variables may modify the behavior of Info-mode in Emacs;
you may wish to set one or several of these variables interactively, or
in your ~/.emacs init file. See Examining and Setting Variables. The stand-alone Info reader program has its own set of
variables, described in Manipulating Variables.
Info-directory-list
nil (try default directory). If not
initialized Info uses the environment variable INFOPATH to
initialize it, or Info-default-directory-list if there is no
INFOPATH variable in the environment.
If you wish to customize the Info directory search list for both Emacs
info and stand-alone Info, it is best to set the INFOPATH
environment variable, since that applies to both programs.
Info-additional-directory-list
dir file.
Info-fontify
nil value, enables highlighting of Info
files. The default is t. You can change how the highlighting
looks by customizing the faces info-node, info-menu-5,
info-xref, info-header-xref, info-header-node,
info-title-n-face (where n is the level of the
section, a number between 1 and 4), and info-menu-header. To
customize a face, type M-x customize-face <RET> face
<RET>, where face is one of the face names listed here.
Info-use-header-line
nil, Emacs puts in the Info buffer a header line showing
the Next, Prev, and Up links. A header line does
not scroll with the rest of the buffer, making these links always
visible.
Info-scroll-prefer-subnodes
nil value, <SPC> and <BACKSPACE> (or
<DEL>) keys in a menu visit subnodes of the current node before
scrolling to its end or beginning, respectively. For example, if the
node's menu appears on the screen, the next <SPC> moves to a
subnode indicated by the following menu item. Setting this option to
nil results in behavior similar to the stand-alone Info reader
program, which visits the first subnode from the menu only when you
hit the end of the current node. The default is t.
Info-enable-active-nodes
nil value, allows Info to execute Lisp code
associated with nodes. The Lisp code is executed when the node is
selected. The Lisp code to be executed should follow the node
delimiter (the DEL character) and an execute: tag, like
this:
^_execute: (message "This is an active node!")
Info-enable-edit
nil, disables the e (Info-edit) command. A
non-nil value enables it. See Edit.
makeinfo is a utility that converts a Texinfo file into an Info
file; texinfo-format-region and texinfo-format-buffer are
GNU Emacs functions that do the same.
See Overview of Texinfo, to learn how to write a Texinfo file.
See Creating an Info File, to learn how to create an Info file from a Texinfo file.
See Installing an Info File, to learn how to install an Info file after you have created one.
This is an alphabetical listing of all the commands, variables, and topics discussed in this document.
1 through 9 (Info mode)? (Info mode)b (Info mode)BACKSPACE (Info mode)C-l (Info mode)d (Info mode)DEL (Info mode)e (Info mode)f (Info mode)g (Info mode)i (Info mode)Info-additional-directory-list: Emacs Info Variables
Info-directory: Help-Int
Info-directory-list: Emacs Info Variables
Info-edit: Expert
Info-enable-active-nodes: Emacs Info Variables
Info-enable-edit: Emacs Info Variables
Info-exit: Help-Q
Info-follow-reference: Help-Xref
Info-fontify: Emacs Info Variables
Info-goto-node: Expert
Info-index: Info Search
Info-last: Help-Int
Info-menu: Help-M
Info-mouse-follow-nearest-node: Help-M
Info-nth-menu-item: Expert
Info-scroll-down: Help-^L
Info-scroll-prefer-subnodes: Emacs Info Variables
Info-scroll-up: Help-^L
Info-search: Info Search
Info-summary: Help-^L
Info-tagify: Tags
Info-top-node: Help-Int
Info-up: Help-FOO
Info-use-header-line: Emacs Info Variables
Info-validate: Checking
l (Info mode)m (Info mode)M-s (Info mode)Mouse-2 (Info mode)n (Info mode)p (Info mode)PAGEDOWN (Info mode)PAGEUP (Info mode)q (Info mode)s (Info mode)SPC (Info mode)t (Info mode)u (Info mode)The key which
we call "Backspace or DEL" in this manual is labeled differently on
different keyboards. Look for a key which is a little ways above the
<ENTER> or <RET> key and which you normally use outside Emacs
to erase the character before the cursor, i.e. the character you
typed last. It might be labeled Backspace or <- or
DEL, or sometimes Delete.
If
you put in a ^L to end a new node, be sure that there is a
^_ after it to start the next one, since ^L cannot
start a node. Also, a nicer way to make a node boundary be a
page boundary as well is to put a ^L right after the
^_.