Sections of the manual pages
The manual Sections are traditionally defined as follows:
1 Commands (Programs)
Those commands that can be executed by the user from within
2 System calls
Those functions which must be performed by the kernel.
3 Library calls
Most of the libc functions.
4 Special files (devices)
Files found in /dev.
5 File formats and conventions
The format for /etc/passwd and other human-readable files.
7 Overview, conventions, and miscellaneous
Overviews of various topics, conventions and protocols,
character set standards, and miscellaneous other things.
8 System management commands
Commands like mount(8), many of which only root can