xenial
16.04 LTS
bionic
18.04 LTS
eoan
19.10
focal
20.04 LTS
Section Description
....(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)
pam.d(5)pam.d(5)pam.d(5)pam.d(5)(5) - File formats and conventions eg /etc/passwd
....(6) - Games
....(7) - Miscellaneous (including macro packages and conventions)
....(8) - System administration commands (usually only for root)