Manual

Most UNIX systems have online manual pages.

MAN(1)                     OpenBSD Reference Manual                     MAN(1)
NAME
    man - display the on-line manual pages
SYNOPSIS
    man [-achw] [-C file] [-M path] [-m path] [-S subsection] [-s section]
        [section] name [...]
    man -f command
    man -k keyword
DESCRIPTION

The types of manpages have sections which they are grouped in. Here is the manual page layout of BSD:

Section 1

General commands (tools and utilities)

Section 2

System calls and error numbers

Section 3

Library functions, especially for C and Tk

Section 4

Special files and hardware support

Section 5

File formats, especially configuration files

Section 6

Games

Section 7

Miscellaneous information pages

Section 8

System maintenance and operation commands

Section 9

Kernel internals

When someone tells you to run "man 6 tetris", that means that you should read the tetris manpage found in section 6 of the manpages. Sometimes the same manpage name exists, but in different sections. One example is the fstat manpage it exists in sections 1 and 2. The lower number sections take precedence over higher numbered sections. Thus, to see the manpage for fstat in section 2 you would type:

$ man 2 fstat

Similarely functions, syscalls or commands are sometimes mentioned with the section of manpages in brackets behind them like so: fstat(2), you'll see this mentioned a lot in this wiki.

Searching for Manual Pages

It is possible to do a keyword search in the manpage system.

$ man -k filesystem
OpenBSD::Vstat (3p) - virtual filesystem for pkg_add(1) simulations
dump (8) - filesystem backup
fstab (5) - static information about the filesystems
...

Another command synonymous to man -k is apropos:

$ apropos archiver
tar (1) - tape archiver

Do notice that the section of the manpage is displayed in the keyword search, this is to ease viewing the particular manpage. Do note that when you are on Solaris you may have to build the manual page index in order to search for keywords. This is done with the catman command:

$ catman -w 

$MANPATH is used, unless something else is explicitly specified.

Location of Manual Pages

In BSD the default manual pages are located in /usr/share/man. This can be changed with the MANPATH environment variable:

$ export MANPATH=/usr/local/man
$ man ls
man: no entry for ls in the manual. 
$ unset MANPATH
$ man ls
LS(1)                      OpenBSD Reference Manual                      LS(1)
...

Another manpage section can be added on to the current MANPATH:

$ export MANPATH=/usr/share/man:/usr/local/man