1. Changing the file owner:

The chown command is used to change the owner of a file or directory. For example, to change the file owner test.txt the following command can be used on the john user:

$ chown john test.txt

2. Changing the owner and group of the file:

The chown command can be used to change the owner and group of a file or directory. For example, to change the file owner test.txt the following command can be used for the john user and the users group:

$ chown john:users test.txt

3. Change the owner and group for all files in the directory:

The chown command can be used to change the owner and group for all files in a directory. For example, to change the owner and group for all files in the test directory to the john user and the users group, you can use the following command:

$ chown -R john:users test/