linux：

The owner and the owner group of a file created in the system by a user in the system are the owner and base group of that user, respectively.

Ordinary users cannot change the owner and group of a file because ordinary users do not have the right to execute the Chown command.

When we are in a user's identity to login to our system, the system will give the user returns to a shell process, when the user access to a file, must be based on the process to access t