$ curl cheat.sh/
# chgrp
# Change group ownership of files and directories.
# More information: <https://www.gnu.org/software/coreutils/chgrp>.

# Change the owner group of a file/directory:
chgrp group path/to/file_or_directory

# Recursively change the owner group of a directory and its contents:
chgrp -R group path/to/directory

# Change the owner group of a symbolic link:
chgrp -h group path/to/symlink

# Change the owner group of a file/directory to match a reference file:
chgrp --reference=path/to/reference_file path/to/file_or_directory

$
Follow @igor_chubin cheat.sh tldr