I am using Linux (RHEL 7.5) and have a directory containing some files and directories that have 750 permissions (or lower), and some files and directories that have 777 permissions.
I wish to increase the permissions (recursively) for those files and directories that are at 750 (or below) to 755, but to leave those that have permissions 777 as they are.
How can I accomplish this selective "ratcheting up" of permissions?