chgrp
[options] newgroup filesChange the ownership of one or more files to newgroup. newgroup is either a group ID number or a group name located in /etc/group. You must own the file or be a privileged user to succeed with this command.
-f
Force error messages to be suppressed.
-h
Change the group on symbolic links. Normally, chgrp acts on the file referenced by a symbolic link, not on the link itself. (This option is not necessarily available on all Unix systems.)
-R
Recursively descend through the directory, including subdirectories and symbolic links, setting the specified group ID as it proceeds.