Most of bash commands have an help manual which can be opened in the command line by using the command man:
man bash
man ssh_config
man sshd
On the first line of every man page for a command, we can see the name of the command immediately followed by a number within parentheses:
bash(1)
ssh_config(5)
sshd(8)
What does this number mean ? Does any of you know a page which would list all possible values of numbers which can appear between these parentheses and their meaning ?
Sections of the man pages
This page describes the conventions that should be employed when writing man pages for the Linux man-pages project, which documents the user-space API provided by the Linux kernel and the GNU C library. The project thus provides most of the pages in Section 2, as well as many of the pages that appear in Sections 3, 4, 5, and 7 of the man pages on a Linux system. The conventions described on this page may also be useful for authors writing man pages for other projects.
Sections of the manual pages The manual Sections are traditionally defined as follows:
1 User commands (Programs) Those commands that can be executed by the user from within a shell. 2 System calls Those functions which wrap operations performed by the kernel. 3 Library calls All library functions excluding the system call wrappers (Most of the libc functions). 4 Special files (devices) Files found in /dev which allow to access to devices through the kernel. 5 File formats and configuration files Describes various human-readable file formats and configuration files. 6 Games Games and funny little programs available on the system. 7 Overview, conventions, and miscellaneous Overviews or descriptions of various topics, conventions and protocols, character set standards, the standard filesystem layout, and miscellaneous other things. 8 System management commands Commands like mount(8), many of which only root can execute.
See man man for details =)