4.Linux获取帮助

* Help
syntax: (any commond) -h
(any commond) --help

* Man
syntax: man (any commond)
man -k  anywords (view list of commonds about the 'anywords')

* Info  more detail than man


Infomormation in Man and Info could be searched by "/"


* Doc  document of program in folder /usr/share/doc