group ownership (update the group ID of files.)
chgrp [-fhv] [-R [-H | -L | -P]] group file ...
The group operand can be either a group name, or a numeric group ID.
-R Recurse: Change the mode of file hierarchies rooted in the files
instead of just the files themselves.
-R -H Follow symbolic links on the command line
(by default Symbolic links within the tree are not followed.)
-R -L All symbolic links are followed.
-R -P No symbolic links are followed. (default)
-f Force, ignores errors, except for usage errors and doesn't query
about strange modes (unless the user lacks permissions).
-h If the file is a symbolic link, the group ID of the link itself
is changed rather than the file that is pointed to.
-v Verbose, show filenames as the group is modified.
user invoking chgrp must belong to the specified group and be the owner of the
file, or be the super-user.
chgrp utility exits 0 on success, and >0 if an error occurs.
previous versions of this system, symbolic links did not have groups.
The -v option is non-standard and its use in scripts is not recommended.
Assign Ursula as the owner of "MyFile.txt" file in the Shared
chown Ursula /Users/Shared/MyFile.txt
Ursula as the owner, and staff as the group for everything in the "tmp"
chown -R Ursula:staff /Users/Shared/tmp/