centos安装man3

 常用法：

man [section] name

其中section指明手册中的哪一部分，若未指明，则从1开始一次查找，直到找到一个为止。

重点留意：

    1 --- 命令

    2 --- 系统调用

    3 --- 库函数

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 conventions), e.g. man(7),
           groff(7)
       8   System administration commands (usually only for root)
       9   Kernel routines [Non standard]

我使用的阿里云centos 7服务器，使用man的时候发现只有section 1

进行man安装

yum install -y man man-pages

注意：单独安装依然无效，无法查询有些函数（eg: man 2 stat）