下面指的是手册的章节号：
1 General commands通用命令
2 System calls系统调用
3 Library functions, covering in particular the C standard library库函数
4 Special files (usually devices, those found in /dev) and drivers特殊文件和驱动
5 File formats and conventions文件格式和惯例
6 Games and screensavers游戏相关、屏保
7 Miscellanea杂项
8 System administration commands and daemons系统管理命令和后台
比如可以通过输入man 8 mount
