ls -ahl view file owner
chown user name file name
Modify the owner of the file, change the root user's a.txt file, modify the owner to tom
chown tom a.txt
User and group creation
groupadd group name
Create a group monster, create a user fox and put it in the monster group
useradd -g monster fox
Change the orange.txt file of the root user group to the police group
chgrp police orange.txt
Change the user's group
usermod -g group name user name
Change the tom user of the police group to the bandit group
usermod -g bandit tom
