Linux Man Page Section Reference

The numbers and letters in parentheses correspond to man page sections.

(1) General Commands
User commands and tools, for example, file manipulation tools, shells, compilers, web browsers, file and image viewers and editors, and so on.
(2) System Calls
A system call is an entry point into the Linux kernel. Usually, system calls are not invoked directly: instead, most system calls have corresponding C library wrapper functions which perform the steps required in order to invoke the system call.
(3) Library Functions
All library functions excluding the library functions (system call wrappers) described in section 2, which implement system calls.
(4) Special Files
Devices and drivers.
(5) File Formats
File formats and protocols, and the corresponding C structures, if any.
(6) Games
Games and screensavers.
(7) Miscellanea
Conventions and protocols, character set standards, the standard file system layout, and miscellaneous other things.
(8) System Administration
Commands which either can be or are used only by the superuser, like system-administration commands, daemons, and hardware-related commands.
(0p) POSIX Header Files
(1p) POSIX Commands
(3p) POSIX Functions
(n) Tcl/Tk Keywords