chgrp group file ...
The chgrp command changes the group of files and directories.

• Change the group of "folder1" to "group1".
  $ chgrp group1 folder1/
  
• Change the group of "folder1" (and its files and sub-directories) to "DOMAIN\group2".
  Use the escape character "\" to escape the character "\".
  You can also use the double quote character """ to delimit the folder path to escape the character "\".
  $ chgrp -R DOMAIN\\group2 folder1/ $ chgrp -R "DOMAIN\group2" folder1/

The following options can be used:
-R |If chgrp is applied to a directory, it will change the group of this directory and all its files and sub-directories. |By default, symbolic links will be changed. |But the linked files of symbolic links will not be changed. -L |If the -R option is specified, symbolic links will not be changed. |But the linked files of symbolic links will be changed. |The -L option overrides any previous -P options. |The -L option is ignored unless the -R option is specified. -P |If the -R option is specified, symbolic links will be changed. |But the linked files of symbolic links will not be changed. |The -P option overrides any previous -L options. |The -P option is ignored unless the -R option is specified. -v |Cause chgrp to be verbose, showing filenames if the group is modified.