Simple command implementation for Linux beginners (2)

Continue to the first Linux basic command learning.

11. The ls command
    displays the files in the current directory. ls -a displays hidden files. ls -l displays all file attributes.
    
12. The vi command
    creates a new file and can be edited after pressing i.
    
    
13. The ps command
    finds running processes.
    
14. kill command
    Delete command. kill -9 force delete.
    
15. The grep command
    matches keywords and filters fields.
    
16. Date command
    Get the current date and time.
    
17. History Command
    Query the operation command made before.