The group field (and optionally owner field) of the named files is changed to group and owner . Alternatively, a decimal gid (uid) may be specified instead of a group name. If the -R flag is used, the changes will be applied recursively to all files in named directories. Only the superuser may execute this command to set arbitrary groups. Normal users can only change the group if they own the file, and the group is their own group (MINIX 3), or one of their supplementary groups (Minix-vmd).