- rm : Delete file or folder
ex : rm -r /folder
>> r = recursive (remove sub files and sub directories)
>> f = remove all files
>> i = interactive for confirmation

- mv :  move or rename file or folder
ex : mv old _file  new_file

- cp : copy file or folder
ex : cp old_folder new_folder

- mkdir : create folder
ex mkdir folder

Ref : http://www.die.net/doc/linux/man/man1/rm.1.html