Using Man Pages

"The Unix approach to on-line documentation works fine if you are interested in documenting a few hundred programs and commands that you, for the most part, can keep in your head anyway. It starts to break down as the number of entries in the system approaches a thousand; add more entries, written by hundreds of authors spread over the continent, and the swelling, itching brain shakes with spasms and strange convulsions."
(The UNIX-HATERS Handbook)

Unix manual pages are created by the man command which finds, prints, and displays entries from the online reference manuals. Man pages are vendor specific by necessity, as individual commands and options to them may vary from operating system to operating system.

Man pages are organized into sections. The content of each section can vary slightly between vendors, however they are basically ordered as follows:

User commands
System calls
C library routines
Device drivers and network interfaces
File formats
Games and demos
Misc. (ASCII, macro packages, tables, etc)
Commands for system administration
Locally installed manual pages. (i.e. X11)

The best way to determine the exact organization of a particular set of man pages is to peruse them.

The manual pages can be accessed via the man command. For example, entering, man ls, means that all sections of the manual pages are searched for information on the ls command. Searches can also be limited to a particular section, keyword, filename or combinations of these. Typing man man at the command line will print a list of all the options for man as well as instructions on how to do searches by section, keyword, filename, etc.

The X Window System uses xman, a graphical browsing tool for viewing man pages. With xman the user is presented with a listing of all available man pages and a "Sections" menu.

Because man pages are tersely written they can be most helpful for looking up things such as the options to or syntax of a command. They can also be useful for finding out what command performs a particular function, by using the function as the keyword for a keyword search to locate the command. Due to the style in which they're written, man pages are generally not a a good place to go for learning the basics of how a command works.

The best way to become familiar with how man pages differ from vendor to vendor is to look at and compare the pages. Please note, these are not local documents and may take awhile to load.

5. So why do some commands not have a man page?