Info



The  command is [[Article description::used to view and navigate info pages that contain computer program documentation. It is part of the Texinfo documentation system.]]

Most users will be familiar with the man documentation system. While man is good for quickly looking up items, it lacks structure in linking man pages together. Info pages can link with other pages, create menus and ease navigation in general. The contents of the man pages is sometimes complimentary to the info system, sometimes they will be different, sometimes only one system will contain anything at all.

Info pages are available even when a system is not connected to the Internet. The files are usually stored in but are viewed with a dedicated program, such as the  command.

It is a real advantage to have documentation present on a system in a standardized and accessible way. Getting into the habit of looking for answers in the info and man pages is very good practice, they often contain the most complete documentation available.

Installation
Info may already be present on some systems, in which case this section can be skipped. Type  (belongs to, which is usually part of the system set) to determine if  is already installed.

Emerge
Install package:

Pinfo
is a colorized alternative to the viewer, with enhanced browsing facilities. If desired, this could be installed instead of or in parallel to (in which case substitute  for  when following the rest of this document):

Browsing info pages
To begin viewing - and navigating through - the info pages, invoke with no arguments. The user will be presented with an overview of the documentation stored on their system:

Now that info is started, the screen will be similar to this:

Right now there are a bunch of entries with an asterisk before them. These are menu items for navigating through different node levels.

There are two ways of selecting menus, either with arrows or by number. In order to look at the wget info page, navigating with the arrow keys, use the key until reaching the line for wget:

Once on this line, hit the key to select the menu item. This will bring up the info page for wget:

In terms of nodes, this is considered the  node for the wget page. Consider the  node to be the same as the table of contents for that particular info page.

To navigate the page itself, users have a couple of different methods. First off is the standard info method. This is using the key to move forward a page and the / keys to move back a page. This is the recommended method as it automatically advances/retreats to the appropriate node in the document. In order to skip entire nodes without using //, users can also use the (advance backwards) and  (advance forwards) keys.

Another way to navigate is through the / keys. These work, but they will not advance/retreat like // will.

As mentioned earlier, there are two ways of selecting menus. The second way will now be described here. The numbers  can be used to reference to the first-ninth menu entries in a document. This can be used to quickly peruse through documents. For example, users can press to reach the   menu entry. So press and it will bring up the   screen:

Here is a good time to note a few things. First off the top header section. This header shows the navigation capable from this particular screen. The page indicated by  can be accessed by pressing the  key, and the page indicated by   can be accessed by pressing the  key. Please note that this will only work for the same level. If overused users could round up in totally unrelated content. It's better to use //// to navigate in a linear fashion.

If for some reason users get lost, there are a few ways to get out. First is the key. This will take the user straight to the toplevel (table of contents) for the particular info page being browsed. If users want to return to the last page looked out, they can do so with the key. If users want to go to the above level, they can do so with the key. The next chapter will look at searching for content.

Navigating to other info pages
Now that users can navigate an individual info page, it's important to look at accessing other info pages. The first obvious way is to go to the info page through the dir index listing of info pages. To get to the dir index from deep within a document, simply press the key. From there users can search for the appropriate page they want. However, if they know the actual page, there is an easier way through the  command. To go to an info page by name, type to bring up the prompt and enter the name of the page in parentheses:

This will bring up the libc page as shown here:

Now that users know how to go to info pages by name, the next section will look at searching for pieces of information using the info page's index.

Searching using an index
The following example will describe how to lookup the  function of the C library using the libc info page's index. Users should still be at the libc info page from the last section, and if not, they can use the Goto node command to do so. To utilize the index search, hit the key to bring up the prompt, then enter the search term:

After pressing upon completion of our query, users are brought to the libc definition for  :

Users have successfully performed a search using the  info page index. However, sometimes what users want is in the page itself. The next section will look at performing searches within the page.

Searching using the search command
Starting from the previous location at the  node, users will look at searching for the   variation of the   function. To perform a search, press the key to bring up the search prompt, and then enter the query (sprintf in this case):

Hit and it will show the result of the query:

This is the needed function.

Info pages stored on disk
The main info pages are held in. Unlike the man style directory layout, contains what is largely a rather extensive collection of files. These files have the following format:

is the actual name of the page (example: ). is an optional construct that designates another node level (generally these are referenced to by the toplevel of the info document in question).

In order to save space these info pages are compressed using the gzip compression scheme by default. Configure the PORTAGE_COMPRESS variable in to choose different compression algorithms.

Additional info pages can be listed with the INFOPATH environment variable (usually set through the various files).

The file is used when info is run with no parameters. It contains a listing of all info pages available for users to browse.

Additional tools
In order to make things easier for those that wish to browse info pages through a more friendly graphical interface, the following tools are available:


 * - Convert info pages to a browse-able HTML format
 * - based info viewer
 * - A tcl/tk based info browser
 * - A based info browser

The KDE browser Konqueror also allows users to browse info pages through the  URI.

Additional documentation

 * The command can be used to view its own documentation:


 * There is also documentation available in the man pages: