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
whatis
实例
[root@localhost ~]# whatis ls
ls (1) – list directory contents
ls (1p) – list directory contents
[root@localhost ~]# whatis cp
cp (1) – copy files and directories
cp (1p) – copy files
[root@localhost ~]# whatis chown
chown (1) – change file owner and group
chown (1p) – change the file ownership
chown (2) – change ownership of a file
chown (3p) – change owner and group of a file
[root@localhost ~]# whatis man
man (1) – format and display the on-line manual pages
man (1p) – display system documentation
man (7) – macros to format man pages
man (rpm) – A set of documentation tools: man, apropos and whatis.
man-pages (rpm) – Man (manual) pages from the Linux Documentation Project.
man.config [man] (5) – configuration data for man
