• man pages are authoritative text based documents for Command Line commands & programs.
• These get converted to many different formats:
  • Webpage based
  • PDF documents
  • Graphical Help based systems
  • etc..

• man -f <keyward> is the same as using the whatis command
  • Lookup the manual pages referenced by <keyword> and print out the short descriptions of any found.
• man -k <keyword> is the same as using the apropos command
  • Search the man page short descriptions and the man page names for the given <keyword> (as a regular expression).

• the chapter number as a parameter will force the man to return the command from a specific manual chapter
  • e.g. $ man 3 printf
• the -a parameter will display the given command from all manual chapters
  • e.g. $ man -a printf

The below list gives the chapter numbers of the different categories of man pages:

1. Executable programs or shell commands
2. System calls (functions provided by the kernel)
3. Library calls (functions within program libraries)
4. Special files (usually found in /dev)
5. File formats and conventions eg /etc/passwd
6. Games
7. Miscellaneous (including macro packages and conventions), e.g. man(7), groff(7)
8. System administration commands (usually only for root)
9. Kernel routines [Non standard]

A man page consists of several sections. Conventional section names include:

NAME, SYNOPSIS, CONFIGURATION, DESCRIPTION, OPTIONS, EXIT STATUS, RETURN VALUE, ERRORS, ENVIRONMENT, FILES, VERSIONS, CONFORMING TO, NOTES, BUGS, EXAMPLE, AUTHORS, and SEE ALSO.

• Information can be viewed through
  • The Command Line Interface
  • A Graphical Interface
  • Online (Web) Pages
  • Printed documentation
  • etc..

• info is the documentation format that the GNU Project prefers over man
  • It is a “gopher like” system of linked text documents that pre-dates the World Wide Web.
  • In a Terminal, typing info with no arguments displays an index of available topics.
    • those pages can be navigated & viewed using the movement keys (← ↑ → ↓, page up, page down, …)
    • also use the q key to quit, the h key for help, and the enter key to select an item.
  • info <keyword> will search all info files for the Topic given by <keyword>

• A Topic in an info page is called a node
  • use the n key to go to the next node
  • use the p key to go to the previous node
  • use the u key to move up one level in the info index.
• each node may contain menus and linked subtopics, or items
  • an item is a hyperlink, that starts with an asterisk (*) and ends with double-colons (::)

• Most commands have an available short description which can be viewed using the –help or the -h parameter
  • e.g. man –help
  • This provides a summary that is quicker but less extensive than the man pages
  • some commands only use -h, some commands only use –help, and many commands use both

• The BASH terminal has its own build-in commands
  • to view a summary of these built-in commands, simply type in the help command

• All Linux desktop systems have a graphical help application.
  • for Gnome → gnome-help
  • for KDE → khelpcenter

• Linux documentation is also available as part of the package management system.
  • This documentation is found in the /usr/share/doc directory

• there are many online forums, wikis and e-books to provide additional help documentation.