To change the owner or group of a file or other filesystem object, use chown or chgrp respectively. Each of these commands takes a name followed by one or more filenames.

# chown root /etc/passwd
# chgrp wheel /etc/passwd

You can also set the owner and group simultaneously with an alternate form of the chown command:

# chown root.wheel /etc/passwd

You may not use chown unless you are the superuser, but chgrp can be used by anyone to change the group ownership of a file to a group to which they belong.