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2.9. The info Command

An information system gaining popularity on the more lightweight Unix-based systems is info. It's particularly relevant for finding information within Linux and FreeBSD.

Unlike man -- which displays all information on a topic at once, usually routed through some form of paging system such as cat -- info is based on a hypertext like linkage between topic components. You connect to each of the subtopics using character-based commands and typing part or all of the subtopic title -- at least enough to distinguish one subtopic from another.

To use info, you type the command info followed by the Unix command about which you're trying to find information. For instance, to find out more about info itself, you would use the following command line:

info info

This will return the main info introduction page and a menu of subtopics such as:

Getting Started
Advanced Info
Creating an Info File

To access the subtopic, you type the letter m for menu, and then in the prompt that opens at the bottom of the screen, type enough of the letters to distinguish the subtopic menu item from any other. You don't have to complete the command: you can just type enough of the letters followed by a TAB to fill in the rest. Once the subtopic menu item has been filled in, hitting ENTER sends you to the information.

To learn more about using info, you can type the letter h when you're in info and no command line buffer is showing. This brings up basic information about the info command, including the commands you use within info to use the application. These letters are summarized in Table 2-1.

Table 2-1. info commands




To get help on using info


To access a subtopic menu item


To get to next related subtopic


To get to the previous related subtopic


To move forward in the display if it exceeds page size


To move backward in the display if it exceeds page size


To clean up the display if it gets mangled


To get to the first page of the display


To get a list of info commands


To quit info


To return to highest level of info topics


To access the Emacs manual


To search for string within current node

Note that the letter commands are case insensitive: U works the same as u.

Use the d command to pull up the Directory node, the menu of info major topics. In fact, this is a good way to become familiar with info and its contained subtopics -- type d and then use the menu commands to explore each of the major subtopic areas.

For instance, from the Directory Node, typing m followed by typing strings into the command buffer pulls up the strings info node.

When using the info command, if the information doesn't fit within a page, header and footer information will provide you some details about the subtopic, such as the info file, node, and the next nodes within the hierarchy. For instance, when accessing information about man, depending on your system the header reads as follows:

File: *manpages*, Node:man, Up: (dir)

This translates to the info file manpages and the node for man. Typing the u will move you up to the dir info page. Within Emacs, use mouse button two to click on and access a subtopic.

The footer provides a summary of the header information and also provides the number of lines for the topic if the topic page extends past the current screen. To see more information, type the space to page through the topic, just as you do with man.

Much of the help information within info is pulled over as is from manpages and hasn't been converted to the hypertext format of info. Because of this, the use of the m command won't pull up any subtopic. You'll need to use the space key to access the additional information.

To search within an info node/page, type s and then type the search string into the command buffer. The cursor is moved to the first occurance of the string.

-- SP

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