example, the shell’s
read
command has the same name as the
read
system call. This is why man-
ual pages are organized in the following numbered sections:
1. Commands that can be executed from the command line
2. System calls (functions provided by the kernel)
3. Library functions (provided by system libraries)
4. Devices (on Unix-like systems, these are special files, usually placed in the
/dev/
directory)
5. Configuration files (formats and conventions)
6. Games
7. Sets of macros and standards
8. System administration commands
9. Kernel routines
You can specify the section of the manual page that you are looking for: to view the documentation
for the
read
system call, you would type
man 2 read
. When no section is explicitly specified, the
first section that has a manual page with the requested name will be shown. Thus,
man shadow
returns
shadow(5)
because there are no manual pages for
shadow in sections 1–4.
Of course, if you do not know the names of the commands, the manual is not going to be of much
use to you. Enter the
apropos
command, which searches manual pages (or more specifically their
short descriptions) for any keywords that you provide. The
apropos
command then returns a
list of manual pages whose summary mentions the requested keywords along with the one-line
summary from the manual page. If you choose your keywords well, you will find the name of the
command that you need.