使用man 查询函数的使用方法

1. man 2 syscalls 查看所有的系统调用
2. man 2 read查看系统调用read()
   在这两个命令中的2都表示我们要在2类(系统调用类)中查询

使用man man查看man用法,可以得到以下类型
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]