# Change group owner
chgrp -R GROUP /storage/pruhonice1-ibot/shared/GROUP_FOLDER
# Change folder permissions
find /storage/pruhonice1-ibot/shared/GROUP_FOLDER/ -type d -exec chmod 770 '{}' \;
# Change file permissions
find /storage/pruhonice1-ibot/shared/GROUP_FOLDER/ -type f -exec chmod 660 '{}' \;