In our use Linux When you order , How do you know what options are available under this command ?
（ One ） command --help
It's usually Linux Self contained help information .
as ls --help .
（ Two ）man ( something the matter , Looking for a man manual)
man yes linux A manual provided , Contains most of the commands , Function instructions .
The manual is divided into many chapters , use man You can specify different chapters to browse . example ：man ls .
man The chapters in (section) The meaning is as follows ：
1.Standard commands （ Standard command ）
2.System call （ system call ）
3.Library function（ Library function ）
4.Special devices（ Description of equipment documents ,/dev Under the various equipment ）
5.File formats（ file format , as passwd）
6.Games and toys（ Games and entertainment ）
7.Miscellaneous（ miscellaneous , Convention and agreement, etc , for example Linux Archives system , Network protocol ）
8.Adminstrative commands（ Administrator command , as ifconfig）
man The search is carried out according to the chapter number of the manual .
man The following function keys are set ：
（3） Automatic completion
When you type the first few letters of a command , Press tab key , The system will automatically complete the order for us . notes ： The command needs to be uniquely determined .
（4） Historical command
When the system executes some commands , You can press up and down to view previous commands ,history List the commands that have been executed . Drive in as shown in the figure below history after , Display from 1 All the way to 999 Orders , The screenshot is part , Enter after !996
, It shows home List under folder .