Thursday, July 24, 2014

Customizing the UNIX User Environment - Part 5 - Using the GNU info system - Part 2

Customizing the UNIX User Environment


Using the GNU info system


Page layout and node navigation


The info program is a reader for documentation created using the texinfo system.

Info structures text into a hierarchical tree of nodes, with each node containing a description of a specific topic to a specific level of detail.

If you doct specify a node, the info page opens to the top menu of nides as shown here.


You can move around the info page using the SPacebar or Delete keys.

Depending on the type of terminal you're using, the Delete or Backspace keys allow you to move down the current page to view text that comes after the currently displayed screen.


The Spacebar key allows you to move up to viw text that comes before the currently displayed screen.

In this case, there's np text before the currently displayed screen, because this is the first and topmost screen.


The top line of a node acts as its header. The header consists of the following sections







The tile of the current topic is underlined and located below the header.

The title identifies the topic that's being descrbed in the node.


In addition to the title, a node contains a mode line, which identifies the node. The node line indicates how many lines the node contains and where you are within the node.


To move from one node to the next, you type n.

The header changes to reflect a differnt node.

In this case, the header has changed from the ar node to the nm node.

Of you are at the end of a node, you can also use the Spacebar key to move to the next node.


To return to a previous node, you type p.

The header changes to display the previos node. For example, whn you type p while in the nm node, the header changes from the nm node back to the ar node. You can also do this by using the Delete or Backspace key if you're at the beginning of a node.

If your keyboard has Page Up and Page Down keys, you can use them within a node instead of the Spacebar and Delete keys, but they won't open the next or previous node.


Let's say that you want to move up a level from the current node by pressing u.

You can also go back to the beginning of a code by pressing b.


The info page layout contains menus, which allow you to access other nodes. TO move to other nodes using a menu, you use the m option.

For example, to move to the objcopy node, you press M to invoke the minu prompt. Then you type objcopy and you press the Enter key.

Alternatively, you can place the cursor at the befinning of a menu item, in this case objcopy, and then press Enter.


The result shows the objcopy node open


The menu of a particular node is nirmally visible on the page.If there's no visible menu, that node does not have a menu and you may not issue the m option.


The info page may include cross nodes, which you reach through a cross-reference. A cross-reference is a footnote that points at nodes that belong to an isolated section within the structure.

As a result, these footnotes don't have leads to previous, next, or up topics. In this case, you need to use a specific command, such as f, to follow a specific reference, for example nodes associated with topics starting with the letter b.


The result in this case returns the BFD node.


The mode line - you can see how many lines a particular node contains and where you are within a node from the mode line.

The command line - is where you issue navigational commands to traverse the info system documentation. Note that not all commands may be available on all systems.

The Status line generally reflects the state of various keys - whether the numloclk, scroll lock, or insert mode is on or off, The status line is used for information only - you cannot write to it or update it.


You can invoke and use the info system from within an emacs text editor, which interprets the LISP programming language that supports text editing.

Emacs is a real-time display editor that allows you to edit file types, such as plain text, source code, and HTML files


Emacs includes complete online documentation. including a tutorial for new users. It can be customized and extended, and has self-documenting capabilities




The UNIX info reader program enables you to read help documentation formatted using the texinfo system. The info reader is designed to read texinfo fies, which contain documentation on most software developed as part of the GNU project.

When you invoke the Info system, it takes you to a pager environment where text is structured into a hierarhical tree of nodes. Each node contains a description of a specific topic to a specific level of detail. The info page opens to the top menu of nodes if you dont specify a node. You can use the Spacebar and Delete keys to navigare an info page.















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