/usr/bin/chgrp

Usage: /usr/bin/chgrp [OPTION]... GROUP FILE...
  or:  /usr/bin/chgrp [OPTION]... --reference=RFILE FILE...
Change the group of each FILE to GROUP.
With --reference, change the group of each FILE to that of RFILE.

  -c, --changes
         like verbose but report only when a change is made
  -f, --silent, --quiet
         suppress most error messages
  -v, --verbose
         output a diagnostic for every file processed
      --dereference
         affect the referent of each symbolic link (this is
         the default), rather than the symbolic link itself
  -h, --no-dereference
         affect symbolic links instead of any referenced file;
         useful only on systems that can change the ownership of a symlink
      --from=CURRENT_OWNER:CURRENT_GROUP
         change the ownership of each file only if its
         current owner and/or group match those specified here.
         Either may be omitted, in which case a match
         is not required for the omitted attribute
      --no-preserve-root
         do not treat '/' specially (the default)
      --preserve-root
         fail to operate recursively on '/'
      --reference=RFILE
         use RFILE's ownership rather than specifying values.
         RFILE is always dereferenced if a symbolic link.
  -R, --recursive
         operate on files and directories recursively

The following options modify how a hierarchy is traversed when the -R
option is also specified.  If more than one is specified, only the final
one takes effect. -P is the default.

  -H
         if a command line argument is a symlink to a directory, traverse it
  -L
         traverse every symbolic link to a directory encountered
  -P
         do not traverse any symbolic links

      --help
         display this help and exit
      --version
         output version information and exit

Examples:
  /usr/bin/chgrp staff /u      Change the group of /u to "staff".
  /usr/bin/chgrp -hR staff /u  Change the group of /u and subfiles to "staff".

Report bugs to: <bug-coreutils@gnu.org>.
GNU coreutils home page: <https://www.gnu.org/software/coreutils/>
General help using GNU software: <https://www.gnu.org/gethelp/>
Full documentation <https://www.gnu.org/software/coreutils/chgrp>
or available locally via: info '(coreutils) chgrp invocation'