In some manuals online I see numbers in parentheses following the commands, like (sshd(8), ssh_config(5), etc.). What does this mean, and why is it important to indicate/show the number?
See the manual page for the
man command. Ie.
The table below shows the section numbers of the manual followed by the types of pages they contain.
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]
By the way it is also a dropdownbox on the openssh website: