通过man man可查看man page的具体用法。

       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 conventions), e.g. man(7), groff(7)

       8   System administration commands (usually only for root)

       9   Kernel routines [Non standard]