'man' Section Number

The manuals in Linux have been grouped into several sections.

       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  convenâ
           tions), e.g. man(7), groff(7)
       8   System administration commands (usually only for root)
       9   Kernel routines [Non standard]

The default action is to search in all of the available sections, following a pre-defined order and to show only the first page found, even if page exists in several sections. For example, if you want to see the explicit description of /etc/exports ( a configuration file of nfs server) in section 5,

>man 5 export

You can check the table in above simply by

>man man