whatis
查询一个命令执行什么功能
补充说明
whatis命令 是用于查询一个命令执行什么功能，并将查询结果打印到终端上。
whatis命令在用catman -w命令创建的数据库中查找command参数指定的命令、系统调用、库函数或特殊文件名。whatis命令显示手册部分的页眉行。然后可以发出man命令以获取附加的信息。whatis命令等同于使用man -f命令。
语法
1whatis
实例
1[[email protected] ~]# whatis ls
2ls (1) - list directory contents
3ls (1p) - list directory contents
4
5[[email protected] ~]# whatis cp
6cp (1) - copy files and directories
7cp (1p) - copy files
8
9[[email protected] ~]# whatis chown
10chown (1) - change file owner and group
11chown (1p) - change the file ownership
12chown (2) - change ownership of a file
13chown (3p) - change owner and group of a file
14
15[[email protected] ~]# whatis man
16man (1) - format and display the on-line manual pages
17man (1p) - display system documentation
18man (7) - macros to format man pages
19man (rpm) - A set of documentation tools: man, apropos and whatis.
20man-pages (rpm) - Man (manual) pages from the Linux Documentation Project.
21man.config [man] (5) - configuration data for man
来源：https://github.com/jaywcjlove/linux-command