ls: view files in the current directory
All documents and information to view the file: ls -l
All files and hidden files to view the file: ls -a
mkdir: Create a folder
touch: create an empty file
cd ./xxx: enter xxx directory
cd /: back to the root directory
cd:. go to the next level directory
cd ..: go back one level
chmod: change file permissions
chown: Change file for all users
chgep: change the file all groups