What is the purpose of the chown command?
Under traditional System V, both super user and the owner of a file are allowed to change its user ownership. In other words, users are allowed to give away files that they own. BSD restrict the use of the "chown" command to superuser alone, and version of System V that are POSIX compliant impose the same restriction.
chown newuser files; chgrp newgroup files chown newuser.newgroup files; // HPUX use ":" instead of "."