What's GNU: Texinfo

Texinfo maintains six pre-defined indices; the concept, variable, function, keystroke, program, and data type indices. To add to the concept index, for instance:

@cindex History of @code{Foogol}
@cindex @code{Foogol}, History of

The variable index uses @vindex, the function index @findex, and so on.

You can create your own indices, and it is also possible to merge indices; for example to have variables, functions, and concepts all in the same index. These are typically printed at the end of a document, right before the table of contents, with the @printindex command.

We have already seen @code, that sets text in a constant-width or Courier-like font. There are several other commands that provide special output for different items.

@samp   - for in-line code fragments
@file   - for file names
@var    - things that can vary, parameters, values, and so on
@emph   - emphasizes something, using italics
@strong - makes a strong point, using bold
@r      - force roman (normal) text
@i      - force italic text
@b      - force bold text

The latter three are for occasional use, usually the other commands suffice.

Texinfo allows you to easily write lists and simple tables.

@enumerate A @c A list "numbered" A, B, C ...
@item
First item here
@item
Second item here
....
@end enumerate

Leaving off the “A” would have generated a numbered list, and using a small “a” would have used lower-case letters. A simple list with a minus or bullet would be written:

@itemize @bullet
@item
First item here
@item
Second item here
....
@end itemize

This generates a list with bullets for each item. Using @minus would generate a minus sign. (Minus signs and dashes are different characters when typesetting; minuses are longer.)

There are several kind of tables. Each one takes a formatting code that describes how to format the individual items. For instance, a list of command line options would use @samp.

The list of @code{foogol} command line arguments are:
@table @samp
@item -f @var{filename}
Use @var{filename} as the source file.
@item -o @var{prog}
Use @var{prog} as the executable program.
@item -d
Print the date, time of day, and current phase of the moon.
...
@end table

Two other similar commands are @vtable ... @end vtable, and @ftable ... @end ftable. These are just like @table, but they automatically make an entry for each item in the variable and function indices, respectively, which can save you some typing.

There are several commands for formatting text that is marked off in a special fashion, such as examples, quotations, and so on. The primary one is @example ... @end example which is generally used for program or other computer input and output. The text will be printed indented, in a Courier-like font, and it will not be otherwise filled or adjusted.

The @format ... @end format is like @example, but does not do the indenting. You can quote extended pieces of text by enclosing the quote in @quotation ... @end quotation.

After an example, it is typical to continue a thought without starting a new paragraph. To keep the continuation text from being indented like a new paragraph, precede it with @noindent.

This example shows the results of running our program:

@example
$ make_money
Congratulations! You are a rich   Memory fault - core dumped
$
@end example
@noindent
As we can see, there is a small problem somewhere.
...

A distinguishing feature of Texinfo documents is that they are liberally filled with cross-references. There are several kinds of cross-reference statements, all of which take at least a node name as their argument.

@xref{Introduction}, for a description of the
history of @code{Foogol}.

There are longer forms that can take the full title of a node (from the @chapter command, for example). In TeX, the cross-reference will generate a typical cross-reference, including a page number.

See [Introduction], page 12, for a description of the history of Foogol.

In an Info file, the cross-reference commands put cross-references into the text. The cross reference would look like this:

*Note Introduction, for a description of the
history of `Foogol'.

When reading the Info file with a viewer, you can issue a simple command that will instruct the viewer to follow the cross-reference. It is the cross-references that provide the “hypertext” feel to the on-line Info reader. Cross-references are typically references to other nodes within the current document, but they don't have to be! A cross-reference to a node in another Texinfo document can be followed, and the Info reader will go to it just as easily as to a node in the current document.