Change the group ownership of one or more files.
chmod [-cfvR] group files
-c lists only files whose permissions have changed.
-f stops any error message displays.
-v verbosely displays permission changes.
-R recursively changes permissions of files in all subdirectories.
To change the group ownership of one or more files, invoke chgrp with the group name followed by the filenames (you can also change the group ownership by using the chown command).