The chgrp (from change group) command may be used by unprivileged users on Unix-like systems to change the group associated with a file system object (such as a file, directory, or link) to one of which they are a member. A file system object has 3 sets of access permissions, one set for the owner, one set for the group and one set for others. Changing the group of an object could be used to change which users can write to a file.
chgrp [options] group FSO
-R recurse through subdirectories
-v verbosely output names of objects changed. Most useful when "FSO" is a list.
-f force or forge ahead with other objects even if an error is encountered.The group parameter specifies the new group with which the files or directories should be associated. It may either be a symbolic name or an identifier.
The FSO specifies one or more file system objects, which may be the result of an expression like *.conf
The above command changes the group associated with file prog.conf' from wheel to staff (provided the executing user is a member of that group). This could be used to allow members of staff to modify the configuration for programs prog and prox.