Using the GNU info System

Using the GNU info System

Although the man system has been a staple in the Unix world for ages, another documentation system called info has gained some popularity in the Linux world as well. Sometimes you can find info pages for commands that have no associated (or no adequate) manual page. If you need more information about a command, it's a good idea to look for an info page.

The info system works in some ways like the Web. The core of the info system is the info browser. When called without arguments or options, the info browser opens to an index page listing all the topics for which you can obtain info-based help. Try starting the browser now by typing info at the command line:

 [you@workstation20 ~]$ info 

Figure 18.6 shows the info display.

Figure 18.6. When you first launch info, you are greeted by a screen full of index information.

Although the info system might seem clumsy to navigate at first, it contains a wealth of information, often in greater depth than you can find in the man pages.

Navigating the info System

Navigating inside info can be a little tricky, especially for beginners.

As in a web browser, the info pages contain words that link to further information, such as info indexes or documents. Most of these words are followed by single or double colon characters (: or ::). To follow one of these links or open such a document, use the arrow keys to place the cursor over the linking word and then press Enter to select it.

In info, the node represents the fundamental unit of documentation. Usually, when you are viewing a screen full of information, you are looking at a particular info node. Many nodes contain further links to next and previous nodes, which typically represent related information to the screen you're currently viewing, arranged in some kind of logical order. Table 18.4 provides the basic keystrokes for navigating info.

Table 18.4. Basic Keystrokes for Navigating info

Key	Description
Up arrow	Move cursor up
Down arrow	Move cursor down
Left arrow	Move cursor left
Right arrow	Move cursor right
Enter	Follow the link under the cursor to the indicated node (screen full of information)
n	Proceed to the "next" logical node after this one
p	Proceed to the "previous" logical node before this one
u	Return "up" one node in the index, usually to the location that led you to your current node
t	Return to the "top" node or info index page
q	Quit the info system
Spacebar	Display the next screen full of information in the current node

info and emacs Are Very Similar

The info system is built using the emacs editor engine. Thus, you can use many of the common emacs commands you'll learn in future chapters, including buffer-oriented and screen-splitting commands, while browsing info.

For more information on using emacs, refer to Chapter 20, "Creating, Editing, and Saving Text Files."

Using info Efficiently

Although the main index page of the info system is useful to those not familiar with the documentation available through info, it can be time-consuming and bothersome to navigate for those who have used info.

When you are familiar with info, you can call it in much the same way you use the man command, supplying the name of the info document that you want to read as an argument to the command. For example, to read the info page for the ls command, you enter

 [you@workstation20 ~]$ info ls 

Used this way, info functions very much like man; you page through the displayed document using the spacebar and then press q when you are ready to quit.