-f

Prevent this command from printing error messages even when the operation fails to change the group. 

-i

Prompt for confirmation before changing the group for a file or directory. 

-R

Change the group of a directory and every file and directory under that directory to the specified group, and change the shadow file information on each affected file and directory. 

group

Specify a group name from the group database, or a numeric group ID, to give each file named by a file operand. If a numeric group operand exists as a group name in the group database, this command uses the group ID number associated with that name as the group ID. 

file

Specify the path name of the file whose group ID you want to modify. 

dir

Specify the path name of the directory whose group ID you want to modify.