How to get help on Linux using local documentation

The Linux documentation is quite complete and can provide very interesting help. You don’t need Google to know how a particular command works or “how to do it”

First, we need to make some definitions of what terms used for documentation are necessary:

• HowTos: How to Do It — These are documents that detail the procedures for completing a given task;
• Man: Manual Page — These are traditional manuals that cover a wide variety of topics;
• Info: Info Pages — Documentation provided by the Free Software Foundation for GNU software;
• LDP: Linux Documentation Project — Project for making and distributing documentation on Linux.

Finding the Documentation in /usr/share/doc

The /usr/share/doc directory contains much of the documentation for
a Linux distribution and several applications in the form of HOWTOS, FAQs,
README files, installation guides, and user manuals.

The /usr/share/doc/howto subdirectory has nearly 2000 pages of
documentation detailing various tasks step by step.

Here’s an example:

3Dfx-HOWTO.html

AI-Alife-HOWTO.html

Acer-Laptop-HOWTO.html

Alpha-HOWTO.html

Bash-Prog-Intro-HOWTO.html

Benchmarking-HOWTO.html

(…)

This type of documentation is useful when you don’t know how to get started.
a particular task or what tools should be used.

Information about almost all software packages installed on the system can be found in the /usr/share/doc/packages subdirectory. This information may include files with different contents such as README, INSTALL, CHANGES, INFO, FAQ, etc.

How-tos may not always be installed in the distribution, and their path may be different.

Using the
Info pages

An interesting source of
Consult the info pages. This documentation was developed by the project
GNU covers most of the project’s tools.

To access this
documentation, you must use the info command followed by the command name
desired. See an example, typing the command in the shell:

# test info

The info allows navigation between related topics. For
Browse the info, just find a “link” consisting of the symbol “*” and a
Word and hit the enter key.

To move to the next content page, type “N” (Next) and,
to go back, type “P” (Previous). The “q” key exits the info.

The info command without any arguments lists all pages.
existing.

# info

Using the
Manual pages

The manual pages accompany almost every
GNU/Linux programs. They provide a basic description of commands and details.
about how your options work.

A manual page is
viewed as a single text with vertical scrolling. It also documents
parameters used in some configuration files.

The manual documents are divided into sessions according to the
subject discussed. The sessions are numbered from 1 to 9, as follows:

• 1 Executable programs or shell commands;
• 2 System Calls (functions provided by the Kernel);
• 3 Library Calls (functions provided by libraries);
• 4 Special files, especially those located in /dev;
• 5 File formats and conventions;
• 6 Games;
• 7 Macro Packages;
• 8 Administrative Commands;
• 9 Kernel Routines.

It is possible that the same word can refer to a function of
programming, command, or configuration file. In this way it is important
find out in which session we will find the desired documentation.

Each page of the manual is divided into parts:

• NAME: Name of the item searched for with a short description;
• SYNOPSIS: Full description of the use and syntax;
• DESCRIPTION: Brief description of the features;
• OPTIONS: Description of each option and arguments;
• FILES: A list of important files;
• SEE ALSO: A list of items related to the wanted;
• BUGS: Description of possible problems with the item;
• AUTHOR: List of people responsible for the item.

To access the manual, the command is the man followed by the item searched for.
Optionally, the session number can be passed as a parameter.

# Man Passwd

Neste
For example, man views the manual for the passwd command, belonging to session 1.

# Man 5 Passwd

In this example, man will display the manual for the /etc/passwd file.

Navigation within the manual pages is done using the
keys:

• q Exits the manual page;
• PageDown or f Scroll 25 lines down;
• PageUp or w Scroll 25 lines up;

Arrow Up

• or k Scroll 1 line up;

Arrow

• Down or e Scroll 1 line down;

r Redesign the screen (refresh);

• p or g Top of page;
• h Help with the options of manual page;
• s Saves the manual page in text format to the specified file.

Using the
On-line Help

The help resource
Quick is useful to know what options can be used with a particular
command. Almost all GNU/Linux programs offer this feature for
quick inquiries. To trigger the online help, type:

# [command] —help

For example:

# ls —help

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