man command in Linux and Unix

man command, short for manual, provides help for the commands, utilities or function in Linux and Unix systems. Learn about usage , related packages, sections and other interesting facts about man pages.

If you are new to Unix and Linux system and looking for help command in unix or info command in linux to get started, man command is the answer.

man command in Linux and Unix with example & how to use man pages

man command sysntax is very simple as
$man
and to use man pages simply call command with man page as in exampel below :

$man ls
or
$man useradd
$man df

How to find the names of the commands ?

You can refer to the articles unix command line Tutorial and Unix tutorial
Unix Commands Tutorial
Unix Tutorial – Learn Unix OS Basics to get started

man page sections

man pages are divided in to following section names

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

general convention in man pages is 

bold text  – type exactly as shown.
italic text  – replace with applicable argument.
[-abc]  – optional arguments within [ ]
-a|-b    – options delimited by | cannot be used together.
argument  … argument is repeatable.
[expression]  …  entire expression within [ ] is repeatable.

man packages in Linux & Unix

if man command is not working mostlikely the man packages are not installed. here are some examples to install man packages in linux and Unix , Solaris

To install man package in centos , install two packages 

# yum install man-pages
… ok
# yum install man
… ok

To install man package in fedora

#yum install man-db

To install man package in Unix Solaris 
Install two packages SUNWman and SUNWdoc.
Check if they are already installed with

pkginfo SUNWdoc
pkginfo SUNWman

you can install these from cdrom by mounting and using pkgadd command

pkgadd -d <cdrom mount location> SUNWman
pkgadd -d <cdrom mount location> SUNWdoc

What do the numbers in a man page mean?

man pages collection is organized in sections and each section stores a particular topic man pages as follows :

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]

At the end of a man page man page section is indicated by its section numbers like ls(1) manpath(5), ascii(7) represant the section of mabn comntaing the command.

The default action is to search in all of the available in a default order of (“1 1p 8 2 3 3p 4 5 6 7 9 0p n l p o 1x 2x 3x 4x 5x 6x 7x 8x”. This can be overridden by the SECTION directive in /etc/man_db.conf)

 

Related Articles  :

Unix Commands Tutorial
Unix Tutorial – Learn Unix OS Basics to get started

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