linux下man

man就是manual的缩写，用来查看系统中自带的各种参考手册，但是手册页分为好几个部分，如下所示：

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]

在shell中输入 man+数字+命令/函数 即可以查到相关的命令和函数。若不加数字，那man命令默认从数字较小的手册中寻找相关命令和函数。